Rob Jackson and his lab examine the many ways people affect the Earth. They seek basic scientific knowledge and use it to help shape policies and reduce the environmental footprint of global warming, energy extraction, and other issues. They're currently examining the effects of climate change and drought on old-growth forests. They are also working to measure and reduce greenhouse gas emissions through the Global Carbon Project (, which Jackson chairs. Examples of new research Rob leads include establishing a global network of methane tower measurements across the Amazon and at more than 100 sites worldwide and measuring and reducing methane emissions and air pollution from oil and gas wells, city streets, and homes and buildings.

Rob's new book on climate solutions, Into the Clear Blue Sky (Scribner and Penguin Random House) publishes July 30th, 2024. As an author and photographer, Rob has published a previous trade book about the environment (The Earth Remains Forever, University of Texas Press), two books of children’s poems, Animal Mischief and Weekend Mischief (Highlights Magazine and Boyds Mills Press), and recent or forthcoming poems in the journals Southwest Review, Cortland Review, Cold Mountain Review, Atlanta Review, LitHub, and more. His photographs have appeared in many media outlets, including the NY Times, Washington Post, USA Today, US News and World Report, Science, Nature, and National Geographic News.

Rob is a current Djerassi artist in residence and a recent Guggenheim Fellow and sabbatical visitor in the Center for Advanced Study in the Behavioral Sciences. He is also a Fellow in the American Academy of Arts and Sciences, American Association for the Advancement of Science, American Geophysical Union, and Ecological Society of America. He received a Presidential Early Career Award in Science and Engineering from the National Science Foundation, awarded at the White House.

Academic Appointments

Administrative Appointments

  • Board of Advisors, Spark Climate Solutions (2023 - Present)
  • Board of Directors, Center for Advanced Study in the Behavioral Sciences (2022 - Present)
  • Chair, External Advisory Board, School of Global Environmental Sustainability, CSU (2018 - Present)
  • Chair, Publications Committee, Ecological Society of America (2017 - 2020)
  • Chair, Earth System Science Department, Stanford University (2016 - 2019)
  • Advisory Board, School of Global Environmental Sustainability, CSU (2015 - Present)
  • Chair, Global Carbon Project ( (2014 - Present)
  • Senior Associate Dean for Research, Nicholas School of the Environment, Duke University (2010 - 2012)
  • Co-Chair, U.S. Carbon Cycle Science Plan (2009 - 2012)
  • Vice President for Science, Ecological Society of America (2007 - 2011)
  • Director, National Institute for Climate Change Research, Department of Energy (2005 - 2012)
  • Co-Founder and Co-Director, Climate Change Policy Partnership (2005 - 2011)
  • Director, Duke University Center on Global Change (2004 - 2013)
  • President, Biogeosciences Section, American Geophysical Union (2004 - 2006)
  • Director, Duke University Program in Ecology (2002 - 2006)
  • Director, Duke University Laboratory for Isotope Ratio Mass Spectrometry (2000 - 2013)
  • President, Physiological Ecology Section, Ecological Society of America (2000 - 2002)

Honors & Awards

  • Fellow, Djerassi Resident Artists Program (2024)
  • Fellow, American Academy of Arts and Sciences (2022)
  • International Recognition Award, Mexican Carbon Program (PMC) (2021)
  • Fellow, CASBS (2019)
  • Fellow, John Simon Guggenheim Memorial Foundation (2018)
  • Fellow, American Association for the Advancement of Science (2017)
  • Fellow, Ecological Society of America (2012)
  • Fellow, American Geophysical Union (2008)
  • Presidential Early Career Award in Science and Engineering, National Science Foundation (1998)
  • ISI Highly Cited, (2004-present)
  • Distinguished Postdoctoral Fellow for Global Change, Department of Energy, Stanford University
  • Murray F. Buell Award for Excellence in Ecology, Ecological Society of America

Boards, Advisory Committees, Professional Organizations

  • Chair, External Advisory Board, CSU School of Global Environmental Sustainability (2018 - Present)
  • Policy Advisory Board, Carbon Mapper (2022 - Present)
  • External Advisory Board, CREAF, Barcelona, Spain (2015 - Present)
  • Advisory Board, Methane Action (2021 - Present)

Professional Education

  • Ph.D., Utah State University, Ecology (1992)
  • M.S., Utah State University, Statistics (1992)
  • M.S., Utah State University, Ecology (1990)
  • B.S., Rice University, Chemical Engineering (1983)


  • Research Project, Stanford University



  • Research Project, Stanford University



  • Research Project, Stanford University



2023-24 Courses

Stanford Advisees

All Publications

  • Emergent temperature sensitivity of soil organic carbon driven by mineral associations NATURE GEOSCIENCE Georgiou, K., Koven, C. D., Wieder, W. R., Hartman, M. D., Riley, W. J., Pett-Ridge, J., Bouskill, N. J., Abramoff, R. Z., Slessarev, E. W., Ahlstrom, A., Parton, W. J., Pellegrini, A. A., Pierson, D., Sulman, B. N., Zhu, Q., Jackson, R. B. 2024
  • Global Carbon Budget 2023 EARTH SYSTEM SCIENCE DATA Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Bakker, D. E., Hauck, J., Landschutzer, P., Le Quere, C., Luijkx, I. T., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Anthoni, P., Barbero, L., Bates, N. R., Becker, M., Bellouin, N., Decharme, B., Bopp, L., Brasika, I., Cadule, P., Chamberlain, M. A., Chandra, N., Chau, T., Chevallier, F., Chini, L. P., Cronin, M., Dou, X., Enyo, K., Evans, W., Falk, S., Feely, R. A., Feng, L., Ford, D. J., Gasser, T., Ghattas, J., Gkritzalis, T., Grassi, G., Gregor, L., Gruber, N., Gurses, O., Harris, I., Hefner, M., Heinke, J., Houghton, R. A., Hurtt, G. C., Iida, Y., Ilyina, T., Jacobson, A. R., Jain, A., Jarnikova, T., Jersild, A., Jiang, F., Jin, Z., Joos, F., Kato, E., Keeling, R. F., Kennedy, D., Goldewijk, K., Knauer, J., Korsbakken, J., Koertzinger, A., Lan, X., Lefevre, N., Li, H., Liu, J., Liu, Z., Ma, L., Marland, G., Mayot, N., McGuire, P. C., McKinley, G. A., Meyer, G., Morgan, E. J., Munro, D. R., Nakaoka, S., Niwa, Y., O'Brien, K. M., Olsen, A., Omar, A. M., Ono, T., Paulsen, M., Pierrot, D., Pocock, K., Poulter, B., Powis, C. M., Rehder, G., Resplandy, L., Robertson, E., Roedenbeck, C., Rosan, T. M., Schwinger, J., Seferian, R., Smallman, T., Smith, S. M., Sospedra-Alfonso, R., Sun, Q., Sutton, A. J., Sweeney, C., Takao, S., Tans, P. P., Tian, H., Tilbrook, B., Tsujino, H., Tubiello, F., van der Werf, G. R., van Ooijen, E., Wanninkhof, R., Watanabe, M., Wimart-Rousseau, C., Yang, D., Yang, X., Yuan, W., Yue, X., Zaehle, S., Zeng, J., Zheng, B. 2023; 15 (12): 5301-5369
  • Soil carbon storage capacity of drylands under altered fire regimes NATURE CLIMATE CHANGE Pellegrini, A. A., Reich, P. B., Hobbie, S. E., Coetsee, C., Wigley, B., February, E., Georgiou, K., Terrer, C., Brookshire, E. J., Ahlstrom, A., Nieradzik, L., Sitch, S., Melton, J. R., Forrest, M., Li, F., Hantson, S., Burton, C., Yue, C., Ciais, P., Jackson, R. B. 2023; 13 (10)
  • Gas and Propane Combustion from Stoves Emits Benzene and Increases Indoor Air Pollution. Environmental science & technology Kashtan, Y. S., Nicholson, M., Finnegan, C., Ouyang, Z., Lebel, E. D., Michanowicz, D. R., Shonkoff, S. B., Jackson, R. B. 2023


    Exposure pathways to the carcinogen benzene are well-established from tobacco smoke, oil and gas development, refining, gasoline pumping, and gasoline and diesel combustion. Combustion has also been linked to the formation of nitrogen dioxide, carbon monoxide, and formaldehyde indoors from gas stoves. To our knowledge, however, no research has quantified the formation of benzene indoors from gas combustion by stoves. Across 87 homes in California and Colorado, natural gas and propane combustion emitted detectable and repeatable levels of benzene that in some homes raised indoor benzene concentrations above well-established health benchmarks. Mean benzene emissions from gas and propane burners on high and ovens set to 350 °F ranged from 2.8 to 6.5 μg min-1, 10 to 25 times higher than emissions from electric coil and radiant alternatives; neither induction stoves nor the food being cooked emitted detectable benzene. Benzene produced by gas and propane stoves also migrated throughout homes, in some cases elevating bedroom benzene concentrations above chronic health benchmarks for hours after the stove was turned off. Combustion of gas and propane from stoves may be a substantial benzene exposure pathway and can reduce indoor air quality.

    View details for DOI 10.1021/acs.est.2c09289

    View details for PubMedID 37319002

  • Global patterns of water storage in the rooting zones of vegetation NATURE GEOSCIENCE Stocker, B. D., Tumber-Davila, S., Konings, A. G., Anderson, M. C., Hain, C., Jackson, R. B. 2023
  • Extensive global wetland loss over the past three centuries. Nature Fluet-Chouinard, E., Stocker, B. D., Zhang, Z., Malhotra, A., Melton, J. R., Poulter, B., Kaplan, J. O., Goldewijk, K. K., Siebert, S., Minayeva, T., Hugelius, G., Joosten, H., Barthelmes, A., Prigent, C., Aires, F., Hoyt, A. M., Davidson, N., Finlayson, C. M., Lehner, B., Jackson, R. B., McIntyre, P. B. 2023; 614 (7947): 281-286


    Wetlands have long been drained for human use, thereby strongly affecting greenhouse gas fluxes, flood control, nutrient cycling and biodiversity1,2. Nevertheless, the global extent of natural wetland loss remains remarkably uncertain3. Here, we reconstruct the spatial distribution and timing of wetland loss through conversion to seven human land uses between 1700 and 2020, by combining national and subnational records of drainage and conversion with land-use maps and simulated wetland extents. We estimate that 3.4 million km2 (confidence interval 2.9-3.8) of inland wetlands have been lost since 1700, primarily for conversion to croplands. This net loss of 21% (confidence interval 16-23%) of global wetland area is lower than that suggested previously by extrapolations of data disproportionately from high-loss regions. Wetland loss has been concentrated in Europe, the United States and China, and rapidly expanded during the mid-twentieth century. Our reconstruction elucidates the timing and land-use drivers of global wetland losses, providing an improved historical baseline to guide assessment of wetland loss impact on Earth system processes, conservation planning to protect remaining wetlands and prioritization of sites for wetland restoration4.

    View details for DOI 10.1038/s41586-022-05572-6

    View details for PubMedID 36755174

  • Land-use emissions embodied in international trade. Science (New York, N.Y.) Hong, C., Zhao, H., Qin, Y., Burney, J. A., Pongratz, J., Hartung, K., Liu, Y., Moore, F. C., Jackson, R. B., Zhang, Q., Davis, S. J. 2022; 376 (6593): 597-603


    International trade separates consumption of goods from related environmental impacts, including greenhouse gas emissions from agriculture and land-use change (together referred to as "land-use emissions"). Through use of new emissions estimates and a multiregional input-output model, we evaluated land-use emissions embodied in global trade from 2004 to 2017. Annually, 27% of land-use emissions and 22% of agricultural land are related to agricultural products ultimately consumed in a different region from where they were produced. Roughly three-quarters of embodied emissions are from land-use change, with the largest transfers from lower-income countries such as Brazil, Indonesia, and Argentina to more industrialized regions such as Europe, the United States, and China. Mitigation of global land-use emissions and sustainable development may thus depend on improving the transparency of supply chains.

    View details for DOI 10.1126/science.abj1572

    View details for PubMedID 35511968

  • Human well-being and per capita energy use ECOSPHERE Jackson, R. B., Ahlstrom, A., Hugelius, G., Wang, C., Porporato, A., Ramaswami, A., Roy, J., Yin, J. 2022; 13 (4)

    View details for DOI 10.1002/ecs2.3978

    View details for Web of Science ID 000781073700001

  • Global fossil carbon emissions rebound near pre-COVID-19 levels ENVIRONMENTAL RESEARCH LETTERS Jackson, R. B., Friedlingstein, P., Le Quere, C., Abernethy, S., Andrew, R. M., Canadell, J. G., Ciais, P., Davis, S. J., Deng, Z., Liu, Z., Korsbakken, J., Peters, G. P. 2022; 17 (3)
  • Global temperature goals should determine the time horizons for greenhouse gas emission metrics ENVIRONMENTAL RESEARCH LETTERS Abernethy, S., Jackson, R. B. 2022; 17 (2)
  • A tradeoff between plant and soil carbon storage under elevated CO2 Nature Terrer, C., et al 2021; 591: 599–603
  • Atmospheric Methane Removal: A Research Agenda Philosophical Transactions of the Royal Society A Jackson, R. B., et al 2021; 379: 20200454

    View details for DOI 10.1098/rsta.2020.0454

  • Global and regional drivers of land-use emissions in 1961-2017. Nature Hong, C. n., Burney, J. A., Pongratz, J. n., Nabel, J. E., Mueller, N. D., Jackson, R. B., Davis, S. J. 2021; 589 (7843): 554–61


    Historically, human uses of land have transformed and fragmented ecosystems1,2, degraded biodiversity3,4, disrupted carbon and nitrogen cycles5,6 and added prodigious quantities of greenhouse gases (GHGs) to the atmosphere7,8. However, in contrast to fossil-fuel carbon dioxide (CO2) emissions, trends and drivers of GHG emissions from land management and land-use change (together referred to as 'land-use emissions') have not been as comprehensively and systematically assessed. Here we present country-, process-, GHG- and product-specific inventories of global land-use emissions from 1961 to 2017, we decompose key demographic, economic and technical drivers of emissions and we assess the uncertainties and the sensitivity of results to different accounting assumptions. Despite steady increases in population (+144 per cent) and agricultural production per capita (+58 per cent), as well as smaller increases in emissions per land area used (+8 per cent), decreases in land required per unit of agricultural production (-70 per cent) kept global annual land-use emissions relatively constant at about 11 gigatonnes CO2-equivalent until 2001. After 2001, driven by rising emissions per land area, emissions increased by 2.4 gigatonnes CO2-equivalent per decade to 14.6 gigatonnes CO2-equivalent in 2017 (about 25 per cent of total anthropogenic GHG emissions). Although emissions intensity decreased in all regions, large differences across regions persist over time. The three highest-emitting regions (Latin America, Southeast Asia and sub-Saharan Africa) dominate global emissions growth from 1961 to 2017, driven by rapid and extensive growth of agricultural production and related land-use change. In addition, disproportionate emissions are related to certain products: beef and a few other red meats supply only 1 per cent of calories worldwide, but account for 25 per cent of all land-use emissions. Even where land-use change emissions are negligible or negative, total per capita CO2-equivalent land-use emissions remain near 0.5 tonnes per capita, suggesting the current frontier of mitigation efforts. Our results are consistent with existing knowledge-for example, on the role of population and economic growth and dietary choice-but provide additional insight into regional and sectoral trends.

    View details for DOI 10.1038/s41586-020-03138-y

    View details for PubMedID 33505037

  • Temporary reduction in daily global CO2 emissions during the COVID-19 forced confinement NATURE CLIMATE CHANGE Le Quere, C., Jackson, R. B., Jones, M. W., Smith, A. P., Abernethy, S., Andrew, R. M., De-Gol, A. J., Willis, D. R., Shan, Y., Canadell, J. G., Friedlingstein, P., Creutzig, F., Peters, G. P. 2020
  • Pervasive shifts in forest dynamics in a changing world. Science (New York, N.Y.) McDowell, N. G., Allen, C. D., Anderson-Teixeira, K. n., Aukema, B. H., Bond-Lamberty, B. n., Chini, L. n., Clark, J. S., Dietze, M. n., Grossiord, C. n., Hanbury-Brown, A. n., Hurtt, G. C., Jackson, R. B., Johnson, D. J., Kueppers, L. n., Lichstein, J. W., Ogle, K. n., Poulter, B. n., Pugh, T. A., Seidl, R. n., Turner, M. G., Uriarte, M. n., Walker, A. P., Xu, C. n. 2020; 368 (6494)


    Forest dynamics arise from the interplay of environmental drivers and disturbances with the demographic processes of recruitment, growth, and mortality, subsequently driving biomass and species composition. However, forest disturbances and subsequent recovery are shifting with global changes in climate and land use, altering these dynamics. Changes in environmental drivers, land use, and disturbance regimes are forcing forests toward younger, shorter stands. Rising carbon dioxide, acclimation, adaptation, and migration can influence these impacts. Recent developments in Earth system models support increasingly realistic simulations of vegetation dynamics. In parallel, emerging remote sensing datasets promise qualitatively new and more abundant data on the underlying processes and consequences for vegetation structure. When combined, these advances hold promise for improving the scientific understanding of changes in vegetation demographics and disturbances.

    View details for DOI 10.1126/science.aaz9463

    View details for PubMedID 32467364

  • Methane removal and atmospheric restoration Nature Sustainability Jackson, R. B., Solomon, E. I., Canadell, J. G., Cargnello, M., Field, C. B. 2019; 2: 436-438
  • Persistent fossil fuel growth threatens the Paris Agreement and planetary health Environmental Research Letters Jackson, R. B., Friedlingstein, P., Andrew, R. M., Canadell, J. G., Le Quéré, C., Peters, G. P. 2019; 14 (121001)
  • Fire frequency drives decadal changes in soil carbon and nitrogen and ecosystem productivity. Nature Pellegrini, A. F., Ahlström, A., Hobbie, S. E., Reich, P. B., Nieradzik, L. P., Staver, A. C., Scharenbroch, B. C., Jumpponen, A., Anderegg, W. R., Randerson, J. T., Jackson, R. B. 2018; 553 (7687): 194-198


    Fire frequency is changing globally and is projected to affect the global carbon cycle and climate. However, uncertainty about how ecosystems respond to decadal changes in fire frequency makes it difficult to predict the effects of altered fire regimes on the carbon cycle; for instance, we do not fully understand the long-term effects of fire on soil carbon and nutrient storage, or whether fire-driven nutrient losses limit plant productivity. Here we analyse data from 48 sites in savanna grasslands, broadleaf forests and needleleaf forests spanning up to 65 years, during which time the frequency of fires was altered at each site. We find that frequently burned plots experienced a decline in surface soil carbon and nitrogen that was non-saturating through time, having 36 per cent (±13 per cent) less carbon and 38 per cent (±16 per cent) less nitrogen after 64 years than plots that were protected from fire. Fire-driven carbon and nitrogen losses were substantial in savanna grasslands and broadleaf forests, but not in temperate and boreal needleleaf forests. We also observe comparable soil carbon and nitrogen losses in an independent field dataset and in dynamic model simulations of global vegetation. The model study predicts that the long-term losses of soil nitrogen that result from more frequent burning may in turn decrease the carbon that is sequestered by net primary productivity by about 20 per cent of the total carbon that is emitted from burning biomass over the same period. Furthermore, we estimate that the effects of changes in fire frequency on ecosystem carbon storage may be 30 per cent too low if they do not include multidecadal changes in soil carbon, especially in drier savanna grasslands. Future changes in fire frequency may shift ecosystem carbon storage by changing soil carbon pools and nitrogen limitations on plant growth, altering the carbon sink capacity of frequently burning savanna grasslands and broadleaf forests.

    View details for DOI 10.1038/nature24668

    View details for PubMedID 29227988

  • The Ecology of Soil Carbon: Pools, Vulnerabilities, and Biotic and Abiotic Controls ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS, VOL 48 Jackson, R. B., Lajtha, K., Crow, S. E., Hugelius, G., Kramer, M. G., Pineiro, G., Futuyma, D. J. 2017; 48: 419–45
  • Global nitrous oxide budget (1980-2020) EARTH SYSTEM SCIENCE DATA Tian, H., Pan, N., Thompson, R. L., Canadell, J. G., Suntharalingam, P., Regnier, P., Davidson, E. A., Prather, M., Ciais, P., Muntean, M., Pan, S., Winiwarter, W., Zaehle, S., Zhou, F., Jackson, R. B., Bange, H. W., Berthet, S., Bian, Z., Bianchi, D., Bouwman, A. F., Buitenhuis, E. T., Dutton, G., Hu, M., Ito, A., Jain, A. K., Jeltsch-Thommes, A., Joos, F., Kou-Giesbrecht, S., Krummel, P. B., Lan, X., Landolfi, A., Lauerwald, R., Li, Y., Lu, C., Maavara, T., Manizza, M., Millet, D. B., Muehle, J., Patra, P. K., Peters, G. P., Qin, X., Raymond, P., Resplandy, L., Rosentreter, J. A., Shi, H., Sun, Q., Tonina, D., Tubiello, F. N., van der Werf, G. R., Vuichard, N., Wang, J., Wells, K. C., Western, L. M., Wilson, C., Yang, J., Yao, Y., You, Y., Zhu, Q. 2024; 16 (6): 2543-2604
  • Cost modeling of photocatalytic decomposition of atmospheric methane and nitrous oxide ENVIRONMENTAL RESEARCH LETTERS Randall, R., Jackson, R. B., Majumdar, A. 2024; 19 (6)
  • Downstream natural gas composition across US and Canada: implications for indoor methane leaks and hazardous air pollutant exposures ENVIRONMENTAL RESEARCH LETTERS Rowland, S. T., Lebel, E. D., Goldman, J. W., Domen, J. K., Bilsback, K. R., Ruiz, A., Jaeger, J. M., Hill, L. L., Kashtan, Y. S., Finnegan, C., Nicholson, M., Ouyang, Z., Jackson, R. B., Shonkoff, S. C., Michanowicz, D. R. 2024; 19 (6)
  • Nitrogen dioxide exposure, health outcomes, and associated demographic disparities due to gas and propane combustion by U.S. stoves. Science advances Kashtan, Y., Nicholson, M., Finnegan, C. J., Ouyang, Z., Garg, A., Lebel, E. D., Rowland, S. T., Michanowicz, D. R., Herrera, J., Nadeau, K. C., Jackson, R. B. 2024; 10 (18): eadm8680


    Gas and propane stoves emit nitrogen dioxide (NO2) pollution indoors, but the exposures of different U.S. demographic groups are unknown. We estimate NO2 exposure and health consequences using emissions and concentration measurements from >100 homes, a room-specific indoor air quality model, epidemiological risk parameters, and statistical sampling of housing characteristics and occupant behavior. Gas and propane stoves increase long-term NO2 exposure 4.0 parts per billion volume on average across the United States, 75% of the World Health Organization's exposure guideline. This increased exposure likely causes ~50,000 cases of current pediatric asthma from long-term NO2 exposure alone. Short-term NO2 exposure from typical gas stove use frequently exceeds both World Health Organization and U.S. Environmental Protection Agency benchmarks. People living in residences <800 ft2 in size incur four times more long-term NO2 exposure than people in residences >3000 ft2 in size; American Indian/Alaska Native and Black and Hispanic/Latino households incur 60 and 20% more NO2 exposure, respectively, than the national average.

    View details for DOI 10.1126/sciadv.adm8680

    View details for PubMedID 38701214

    View details for PubMedCentralID PMC11068006

  • Atmospheric methane removal may reduce climate risks ENVIRONMENTAL RESEARCH LETTERS Abernethy, S., Jackson, R. B. 2024; 19 (5)
  • Communities conditionally support deployment of direct air capture for carbon dioxide removal in the United States (vol 5, 175, 2024) COMMUNICATIONS EARTH & ENVIRONMENT Scott-Buechler, C., Cain, B., Osman, K., Ardoin, N. M., Fraser, C., Adcox, G., Polk, E., Jackson, R. B. 2024; 5 (1)
  • Boreal-Arctic wetland methane emissions modulated by warming and vegetation activity. Nature climate change Yuan, K., Li, F., McNicol, G., Chen, M., Hoyt, A., Knox, S., Riley, W. J., Jackson, R., Zhu, Q. 2024; 14 (3): 282-288


    Wetland methane (CH4) emissions over the Boreal-Arctic region are vulnerable to climate change and linked to climate feedbacks, yet understanding of their long-term dynamics remains uncertain. Here, we upscaled and analysed two decades (2002-2021) of Boreal-Arctic wetland CH4 emissions, representing an unprecedented compilation of eddy covariance and chamber observations. We found a robust increasing trend of CH4 emissions (+8.9%) with strong inter-annual variability. The majority of emission increases occurred in early summer (June and July) and were mainly driven by warming (52.3%) and ecosystem productivity (40.7%). Moreover, a 2 °C temperature anomaly in 2016 led to the highest recorded annual CH4 emissions (22.3 Tg CH4 yr-1) over this region, driven primarily by high emissions over Western Siberian lowlands. However, current-generation models from the Global Carbon Project failed to capture the emission magnitude and trend, and may bias the estimates in future wetland CH4 emission driven by amplified Boreal-Arctic warming and greening.

    View details for DOI 10.1038/s41558-024-01933-3

    View details for PubMedID 38481421

    View details for PubMedCentralID PMC10927558

  • Global distribution of surface soil organic carbon in urban greenspaces. Nature communications Guo, H., Du, E., Terrer, C., Jackson, R. B. 2024; 15 (1): 806


    Urban greenspaces continue to grow with global urbanization. The global distribution and stock of soil organic carbon (SOC) in urban greenspaces remain largely undescribed and missing in global carbon (C) budgets. Here, we synthesize data of 420 observations from 257 cities in 52 countries to evaluate the global pattern of surface SOC density (0-20 cm depth) in urban greenspaces. Surface SOC density in urban greenspaces increases significantly at higher latitudes and decreases significantly with higher mean annual temperature, stronger temperature and precipitation seasonality, as well as lower urban greenness index. By mapping surface SOC density using a random forest model, we estimate an average SOC density of 55.2 (51.9-58.6) Mg C ha-1 and a SOC stock of 1.46 (1.37-1.54) Pg C in global urban greenspaces. Our findings present a comprehensive assessment of SOC in global urban greenspaces and provide a baseline for future urban soil C assessment under continuing urbanization.

    View details for DOI 10.1038/s41467-024-44887-y

    View details for PubMedID 38280879

    View details for PubMedCentralID 7210308

  • Recent increases in annual, seasonal, and extreme methane fluxes driven by changes in climate and vegetation in boreal and temperate wetland ecosystems GLOBAL CHANGE BIOLOGY Feron, S., Malhotra, A., Bansal, S., Fluet-Chouinard, E., Mcnicol, G., Knox, S. H., Delwiche, K. B., Cordero, R. R., Ouyang, Z., Zhang, Z., Poulter, B., Jackson, R. B. 2024; 30 (1): e17131


    Climate warming is expected to increase global methane (CH4 ) emissions from wetland ecosystems. Although in situ eddy covariance (EC) measurements at ecosystem scales can potentially detect CH4 flux changes, most EC systems have only a few years of data collected, so temporal trends in CH4 remain uncertain. Here, we use established drivers to hindcast changes in CH4 fluxes (FCH4 ) since the early 1980s. We trained a machine learning (ML) model on CH4 flux measurements from 22 [methane-producing sites] in wetland, upland, and lake sites of the FLUXNET-CH4 database with at least two full years of measurements across temperate and boreal biomes. The gradient boosting decision tree ML model then hindcasted daily FCH4 over 1981-2018 using meteorological reanalysis data. We found that, mainly driven by rising temperature, half of the sites (n = 11) showed significant increases in annual, seasonal, and extreme FCH4 , with increases in FCH4 of ca. 10% or higher found in the fall from 1981-1989 to 2010-2018. The annual trends were driven by increases during summer and fall, particularly at high-CH4 -emitting fen sites dominated by aerenchymatous plants. We also found that the distribution of days of extremely high FCH4 (defined according to the 95th percentile of the daily FCH4 values over a reference period) have become more frequent during the last four decades and currently account for 10-40% of the total seasonal fluxes. The share of extreme FCH4 days in the total seasonal fluxes was greatest in winter for boreal/taiga sites and in spring for temperate sites, which highlights the increasing importance of the non-growing seasons in annual budgets. Our results shed light on the effects of climate warming on wetlands, which appears to be extending the CH4 emission seasons and boosting extreme emissions.

    View details for DOI 10.1111/gcb.17131

    View details for Web of Science ID 001145943100001

    View details for PubMedID 38273508

  • Net-zero approaches must consider Earth system impacts to achieve climate goals NATURE CLIMATE CHANGE Zickfeld, K., Macisaac, A. J., Canadell, J. G., Fuss, S., Jackson, R. B., Jones, C. D., Lohila, A., Matthews, H., Peters, G. P., Rogelj, J., Zaehle, S. 2023; 13 (12): 1298-1305
  • Characterizing Performance of Freshwater Wetland Methane Models Across Time Scales at FLUXNET-CH<sub>4</sub> Sites Using Wavelet Analyses JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES Zhang, Z., Bansal, S., Chang, K., Fluet-Chouinard, E., Delwiche, K., Goeckede, M., Gustafson, A., Knox, S., Leppanen, A., Liu, L., Liu, J., Malhotra, A., Markkanen, T., Mcnicol, G., Melton, J. R., Miller, P. A., Peng, C., Raivonen, M., Riley, W. J., Sonnentag, O., Aalto, T., Vargas, R., Zhang, W., Zhu, Q., Zhu, Q., Zhuang, Q., Windham-Myers, L., Jackson, R. B., Poulter, B. 2023; 128 (11)
  • Impacts of climate change, population growth, and power sector decarbonization on urban building energy use. Nature communications Wang, C., Song, J., Shi, D., Reyna, J. L., Horsey, H., Feron, S., Zhou, Y., Ouyang, Z., Li, Y., Jackson, R. B. 2023; 14 (1): 6434


    Climate, technologies, and socio-economic changes will influence future building energy use in cities. However, current low-resolution regional and state-level analyses are insufficient to reliably assist city-level decision-making. Here we estimate mid-century hourly building energy consumption in 277 U.S. urban areas using a bottom-up approach. The projected future climate change results in heterogeneous changes in energy use intensity (EUI) among urban areas, particularly under higher warming scenarios, with on average 10.1-37.7% increases in the frequency of peak building electricity EUI but over 110% increases in some cities. For each 1 °C of warming, the mean city-scale space-conditioning EUI experiences an average increase/decrease of ~14%/ ~ 10% for space cooling/heating. Heterogeneous city-scale building source energy use changes are primarily driven by population and power sector changes, on average ranging from -9% to 40% with consistent south-north gradients under different scenarios. Across the scenarios considered here, the changes in city-scale building source energy use, when averaged over all urban areas, are as follows: -2.5% to -2.0% due to climate change, 7.3% to 52.2% due to population growth, and -17.1% to -8.9% due to power sector decarbonization. Our findings underscore the necessity of considering intercity heterogeneity when developing sustainable and resilient urban energy systems.

    View details for DOI 10.1038/s41467-023-41458-5

    View details for PubMedID 37852971

    View details for PubMedCentralID PMC10584859

  • Upscaling Wetland Methane Emissions From the FLUXNET-CH4 Eddy Covariance Network (UpCH4 v1.0): Model Development, Network Assessment, and Budget Comparison AGU ADVANCES McNicol, G., Fluet-Chouinard, E., Ouyang, Z., Knox, S., Zhang, Z., Aalto, T., Bansal, S., Chang, K., Chen, M., Delwiche, K., Feron, S., Goeckede, M., Liu, J., Malhotra, A., Melton, J. R., Riley, W., Vargas, R., Yuan, K., Ying, Q., Zhu, Q., Alekseychik, P., Aurela, M., Billesbach, D. P., Campbell, D. I., Chen, J., Chu, H., Desai, A. R., Euskirchen, E., Goodrich, J., Griffis, T., Helbig, M., Hirano, T., Iwata, H., Jurasinski, G., King, J., Koebsch, F., Kolka, R., Krauss, K., Lohila, A., Mammarella, I., Nilson, M., Noormets, A., Oechel, W., Peichl, M., Sachs, T., Sakabe, A., Schulze, C., Sonnentag, O., Sullivan, R. C., Tuittila, E., Ueyama, M., Vesala, T., Ward, E., Wille, C., Wong, G., Zona, D., Windham-Myers, L., Poulter, B., Jackson, R. B. 2023; 4 (5)
  • A large nitrogen supply from the stable mineral-associated soil organic matter fraction BIOLOGY AND FERTILITY OF SOILS Villarino, S. H., Talab, E., Contisciani, L., Videla, C., Di Geronimo, P., Mastrangelo, M. E., Georgiou, K., Jackson, R. B., Pineiro, G. 2023
  • Observational constraints reduce model spread but not uncertainty in global wetland methane emission estimates. Global change biology Chang, K. Y., Riley, W. J., Collier, N., McNicol, G., Fluet-Chouinard, E., Knox, S. H., Delwiche, K. B., Jackson, R. B., Poulter, B., Saunois, M., Chandra, N., Gedney, N., Ishizawa, M., Ito, A., Joos, F., Kleinen, T., Maggi, F., McNorton, J., Melton, J. R., Miller, P., Niwa, Y., Pasut, C., Patra, P. K., Peng, C., Peng, S., Segers, A., Tian, H., Tsuruta, A., Yao, Y., Yin, Y., Zhang, W., Zhang, Z., Zhu, Q., Zhu, Q., Zhuang, Q. 2023


    The recent rise in atmospheric methane (CH4 ) concentrations accelerates climate change and offsets mitigation efforts. Although wetlands are the largest natural CH4 source, estimates of global wetland CH4 emissions vary widely among approaches taken by bottom-up (BU) process-based biogeochemical models and top-down (TD) atmospheric inversion methods. Here, we integrate in situ measurements, multi-model ensembles, and a machine learning upscaling product into the International Land Model Benchmarking system to examine the relationship between wetland CH4 emission estimates and model performance. We find that using better-performing models identified by observational constraints reduces the spread of wetland CH4 emission estimates by 62% and 39% for BU- and TD-based approaches, respectively. However, global BU and TD CH4 emission estimate discrepancies increased by about 15% (from 31 to 36 TgCH4 year-1 ) when the top 20% models were used, although we consider this result moderately uncertain given the unevenly distributed global observations. Our analyses demonstrate that model performance ranking is subject to benchmark selection due to large inter-site variability, highlighting the importance of expanding coverage of benchmark sites to diverse environmental conditions. We encourage future development of wetland CH4 models to move beyond static benchmarking and focus on evaluating site-specific and ecosystem-specific variabilities inferred from observations.

    View details for DOI 10.1111/gcb.16755

    View details for PubMedID 37190869

  • Single-blind validation of space-based point-source detection and quantification of onshore methane emissions. Scientific reports Sherwin, E. D., Rutherford, J. S., Chen, Y., Aminfard, S., Kort, E. A., Jackson, R. B., Brandt, A. R. 2023; 13 (1): 3836


    Satellites are increasingly seen as a tool for identifying large greenhouse gas point sources for mitigation, but independent verification of satellite performance is needed for acceptance and use by policy makers and stakeholders. We conduct to our knowledge the first single-blind controlled methane release testing of satellite-based methane emissions detection and quantification, with five independent teams analyzing data from one to five satellites each for this desert-based test. Teams correctly identified 71% of all emissions, ranging from 0.20 [0.19, 0.21] metric tons per hour (t/h) to 7.2 [6.8, 7.6] t/h. Three-quarters (75%) of quantified estimates fell within±50% of the metered value, comparable to airplane-based remote sensing technologies. The relatively wide-area Sentinel-2 and Landsat 8 satellites detected emissions as low as 1.4 [1.3, 1.5, 95% confidence interval] t/h, while GHGSat's targeted system quantified a 0.20 [0.19, 0.21] t/h emission to within 13%. While the fraction of global methane emissions detectable by satellite remains unknown, we estimate that satellite networks could see 19-89% of total oil and natural gas system emissions detected in a recent survey of a high-emitting region.

    View details for DOI 10.1038/s41598-023-30761-2

    View details for PubMedID 36882586

  • Reconciling the bottom-up and top-down estimates of the methane chemical sink using multiple observations ATMOSPHERIC CHEMISTRY AND PHYSICS Zhao, Y., Saunois, M., Bousquet, P., Lin, X., Hegglin, M. I., Canadell, J. G., Jackson, R. B., Zheng, B. 2023; 23 (1): 789-807
  • Modeled production, oxidation and transport processes of wetland methane emissions in temperate, boreal, and Arctic regions. Global change biology Ueyama, M., Knox, S. H., Delwiche, K. B., Bansal, S., Riley, W. J., Baldocchi, D., Hirano, T., McNicol, G., Schafer, K., Windham-Myers, L., Poulter, B., Jackson, R. B., Chang, K. Y., Chen, J., Chu, H., Desai, A. R., Gogo, S., Iwata, H., Kang, M., Mammarella, I., Peichl, M., Sonnentag, O., Tuittila, E. S., Ryu, Y., Euskirchen, E. S., Göckede, M., Jacotot, A., Nilsson, M. B., Sachs, T. 2023


    Wetlands are the largest natural source of methane (CH4 ) to the atmosphere. The eddy covariance method provides robust measurements of net ecosystem exchange of CH4 , but interpreting its spatio-temporal variations is challenging due to the co-occurrence of CH4 production, oxidation, and transport dynamics. Here we estimate these three processes using a data-model fusion approach across 25 wetlands in temperate, boreal, and Arctic regions. Our data-constrained model - iPEACE - reasonably reproduced CH4 emissions at 19 of the 25 sites with normalized root mean square error of 0.59, correlation coefficient of 0.82, and normalized standard deviation of 0.87. Among the three processes, CH4 production appeared to be the most important process, followed by oxidation in explaining inter-site variations in CH4 emissions. Based on a sensitivity analysis, CH4 emissions were generally more sensitive to decreased water table than to increased gross primary productivity or soil temperature. For periods with leaf area index (LAI) of ≥20% of its annual peak, plant-mediated transport appeared to be the major pathway for CH4 transport. Contributions from ebullition and diffusion were relatively high during low LAI (<20 %) periods. The lag time between CH4 production and CH4 emissions tended to be short in fen sites (3 ± 2 days) and long in bog sites (13 ± 10 days). Based on a principal component analysis, we found that parameters for CH4 production, plant-mediated transport, and diffusion through water explained 77% of the variance in the parameters across the 19 sites, highlighting the importance of these parameters for predicting wetland CH4 emissions across biomes. These processes and associated parameters for CH4 emissions among and within the wetlands provide useful insights for interpreting observed net CH4 fluxes, estimating sensitivities to biophysical variables, and modeling global CH4 fluxes.

    View details for DOI 10.1111/gcb.16594

    View details for PubMedID 36630533

  • Paddy rice methane emissions across Monsoon Asia REMOTE SENSING OF ENVIRONMENT Ouyang, Z., Jackson, R. B., McNicol, G., Fluet-Chouinard, E., Runkle, B. K., Papale, D., Knox, S. H., Cooley, S., Delwiche, K. B., Feron, S., Irvin, J., Malhotra, A., Muddasir, M., Sabbatini, S., Alberto, M. R., Cescatti, A., Chen, C., Dong, J., Fong, B. N., Guo, H., Hao, L., Iwata, H., Jia, Q., Ju, W., Kang, M., Li, H., Kim, J., Reba, M. L., Nayak, A., Roberti, D., Ryu, Y., Swain, C., Tsuang, B., Xiao, X., Yuan, W., Zhang, G., Zhang, Y. 2023; 284
  • The global spectrum of plant form and function: enhanced species-level trait dataset. Scientific data Díaz, S., Kattge, J., Cornelissen, J. H., Wright, I. J., Lavorel, S., Dray, S., Reu, B., Kleyer, M., Wirth, C., Prentice, I. C., Garnier, E., Bönisch, G., Westoby, M., Poorter, H., Reich, P. B., Moles, A. T., Dickie, J., Zanne, A. E., Chave, J., Wright, S. J., Sheremetiev, S. N., Jactel, H., Baraloto, C., Cerabolini, B. E., Pierce, S., Shipley, B., Casanoves, F., Joswig, J. S., Günther, A., Falczuk, V., Rüger, N., Mahecha, M. D., Gorné, L. D., Amiaud, B., Atkin, O. K., Bahn, M., Baldocchi, D., Beckmann, M., Blonder, B., Bond, W., Bond-Lamberty, B., Brown, K., Burrascano, S., Byun, C., Campetella, G., Cavender-Bares, J., Chapin, F. S., Choat, B., Coomes, D. A., Cornwell, W. K., Craine, J., Craven, D., Dainese, M., de Araujo, A. C., de Vries, F. T., Domingues, T. F., Enquist, B. J., Fagúndez, J., Fang, J., Fernández-Méndez, F., Fernandez-Piedade, M. T., Ford, H., Forey, E., Freschet, G. T., Gachet, S., Gallagher, R., Green, W., Guerin, G. R., Gutiérrez, A. G., Harrison, S. P., Hattingh, W. N., He, T., Hickler, T., Higgins, S. I., Higuchi, P., Ilic, J., Jackson, R. B., Jalili, A., Jansen, S., Koike, F., König, C., Kraft, N., Kramer, K., Kreft, H., Kühn, I., Kurokawa, H., Lamb, E. G., Laughlin, D. C., Leishman, M., Lewis, S., Louault, F., Malhado, A. C., Manning, P., Meir, P., Mencuccini, M., Messier, J., Miller, R., Minden, V., Molofsky, J., Montgomery, R., Montserrat-Martí, G., Moretti, M., Müller, S., Niinemets, Ü., Ogaya, R., Öllerer, K., Onipchenko, V., Onoda, Y., Ozinga, W. A., Pausas, J. G., Peco, B., Penuelas, J., Pillar, V. D., Pladevall, C., Römermann, C., Sack, L., Salinas, N., Sandel, B., Sardans, J., Schamp, B., Scherer-Lorenzen, M., Schulze, E. D., Schweingruber, F., Shiodera, S., Sosinski, Ê., Soudzilovskaia, N., Spasojevic, M. J., Swaine, E., Swenson, N., Tautenhahn, S., Thompson, K., Totte, A., Urrutia-Jalabert, R., Valladares, F., van Bodegom, P., Vasseur, F., Verheyen, K., Vile, D., Violle, C., von Holle, B., Weigelt, P., Weiher, E., Wiemann, M. C., Williams, M., Wright, J., Zotz, G. 2022; 9 (1): 755


    Here we provide the 'Global Spectrum of Plant Form and Function Dataset', containing species mean values for six vascular plant traits. Together, these traits -plant height, stem specific density, leaf area, leaf mass per area, leaf nitrogen content per dry mass, and diaspore (seed or spore) mass - define the primary axes of variation in plant form and function. The dataset is based on ca. 1 million trait records received via the TRY database (representing ca. 2,500 original publications) and additional unpublished data. It provides 92,159 species mean values for the six traits, covering 46,047 species. The data are complemented by higher-level taxonomic classification and six categorical traits (woodiness, growth form, succulence, adaptation to terrestrial or aquatic habitats, nutrition type and leaf type). Data quality management is based on a probabilistic approach combined with comprehensive validation against expert knowledge and external information. Intense data acquisition and thorough quality control produced the largest and, to our knowledge, most accurate compilation of empirically observed vascular plant species mean traits to date.

    View details for DOI 10.1038/s41597-022-01774-9

    View details for PubMedID 36477373

  • Microbes modify soil nutrient availability and mediate plant responses to elevated CO2 PLANT AND SOIL Pellitier, P. T., Jackson, R. B. 2022
  • Global Carbon Budget 2022 EARTH SYSTEM SCIENCE DATA Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Gregor, L., Hauck, J., Le Quere, C., Luijkx, I. T., Olsen, A., Peters, G. P., Peters, W., Pongratz, J., Schwingshackl, C., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Alkama, R., Arneth, A., Arora, V. K., Bates, N. R., Becker, M., Bellouin, N., Bittig, H. C., Bopp, L., Chevallier, F., Chini, L. P., Cronin, M., Evans, W., Falk, S., Feely, R. A., Gasser, T., Gehlen, M., Gkritzalis, T., Gloege, L., Grassi, G., Gruber, N., Gurses, O., Harris, I., Hefner, M., Houghton, R. A., Hurtt, G. C., Iida, Y., Ilyina, T., Jain, A. K., Jersild, A., Kadono, K., Kato, E., Kennedy, D., Goldewijk, K., Knauer, J., Korsbakken, J., Landschutzer, P., Lefevre, N., Lindsay, K., Liu, J., Liu, Z., Marland, G., Mayot, N., McGrath, M. J., Metzl, N., Monacci, N. M., Munro, D. R., Nakaoka, S., Niwa, Y., O'Brien, K., Ono, T., Palmer, P., Pan, N., Pierrot, D., Pocock, K., Poulter, B., Resplandy, L., Robertson, E., Rodenbeck, C., Rodriguez, C., Rosan, T. M., Schwinger, J., Seferian, R., Shutler, J. D., Skjelvan, I., Steinhoff, T., Sun, Q., Sutton, A. J., Sweeney, C., Takao, S., Tanhua, T., Tans, P. P., Tian, X., Tian, H., Tilbrook, B., Tsujino, H., Tubiello, F., van der Werf, G. R., Walker, A. P., Wanninkhof, R., Whitehead, C., Wranne, A., Wright, R., Yuan, W., Yue, C., Yue, X., Zaehle, S., Zeng, J., Zheng, B. 2022; 14 (11): 4811-4900
  • Causality guided machine learning model on wetland CH4 emissions across global wetlands AGRICULTURAL AND FOREST METEOROLOGY Yuan, K., Zhu, Q., Li, F., Riley, W. J., Torn, M., Chu, H., McNicol, G., Chen, M., Knox, S., Delwiche, K., Wu, H., Baldocchi, D., Ma, H., Desai, A. R., Chen, J., Sachs, T., Ueyama, M., Sonnentag, O., Helbig, M., Tuittila, E., Jurasinski, G., Koebsch, F., Campbell, D., Schmid, H., Lohila, A., Goeckede, M., Nilsson, M. B., Friborg, T., Jansen, J., Zona, D., Euskirchen, E., Ward, E. J., Bohrer, G., Jin, Z., Liu, L., Iwata, H., Goodrich, J., Jackson, R. 2022; 324
  • Make greenhouse-gas accounting reliable - build interoperable systems Comment NATURE Luers, A., Yona, L., Field, C. B., Jackson, R. B., Mach, K. J., Cashore, B. W., Elliott, C., Gifford, L., Honigsberg, C., Klaassen, L., Matthews, H., Peng, A., Stoll, C., Van Pelt, M., Virginia, R. A., Joppa, L. 2022; 607 (7920): 653-656

    View details for DOI 10.1038/d41586-022-02033-y

    View details for Web of Science ID 000830730300015

    View details for PubMedID 35882990

  • Global stocks and capacity of mineral-associated soil organic carbon. Nature communications Georgiou, K., Jackson, R. B., Vinduskova, O., Abramoff, R. Z., Ahlstrom, A., Feng, W., Harden, J. W., Pellegrini, A. F., Polley, H. W., Soong, J. L., Riley, W. J., Torn, M. S. 2022; 13 (1): 3797


    Soil is the largest terrestrial reservoir of organic carbon and is central for climate change mitigation and carbon-climate feedbacks. Chemical and physical associations of soil carbon with minerals play a critical role in carbon storage, but the amount and global capacity for storage in this form remain unquantified. Here, we produce spatially-resolved global estimates of mineral-associated organic carbon stocks and carbon-storage capacity by analyzing 1144 globally-distributed soil profiles. We show that current stocks total 899 Pg C to a depth of 1m in non-permafrost mineral soils. Although this constitutes 66% and 70% of soil carbon in surface and deeper layers, respectively, it is only 42% and 21% of the mineralogical capacity. Regions under agricultural management and deeper soil layers show the largest undersaturation of mineral-associated carbon. Critically, the degree of undersaturation indicates sequestration efficiency over years to decades. We show that, across 103 carbon-accrual measurements spanning management interventions globally, soils furthest from their mineralogical capacity are more effective at accruing carbon; sequestration rates average 3-times higher in soils at one tenth of their capacity compared to soils at one half of their capacity. Our findings provide insights into the world's soils, their capacity to store carbon, and priority regions and actions for soil carbon management.

    View details for DOI 10.1038/s41467-022-31540-9

    View details for PubMedID 35778395

  • Global patterns of daily CO2 emissions reductions in the first year of COVID-19 NATURE GEOSCIENCE Liu, Z., Deng, Z., Zhu, B., Ciais, P., Davis, S. J., Tan, J., Andrew, R. M., Boucher, O., Ben Arous, S., Canadell, J. G., Dou, X., Friedlingstein, P., Gentine, P., Guo, R., Hong, C., Jackson, R. B., Kammen, D. M., Ke, P., Le Quere, C., Monica, C., Janssens-Maenhout, G., Peters, G. P., Tanaka, K., Wang, Y., Zheng, B., Zhong, H., Sun, T., Schellnhuber, H. 2022
  • A 130-year global inventory of methane emissions from livestock: trends, patterns, and drivers. Global change biology Zhang, L., Tian, H., Shi, H., Pan, S., Chang, J., Dangal, S. R., Qin, X., Wang, S., Tubiello, F. N., Canadell, J. G., Jackson, R. B. 2022


    Livestock contributes approximately one-third of global anthropogenic methane (CH4 ) emissions. Quantifying the spatial and temporal variations of these emissions is crucial for climate change mitigation. Although country-level information is reported regularly through national inventories and global databases, spatially-explicit quantification of century-long dynamics of CH4 emissions from livestock has been poorly investigated. Using the Tier 2 method adopted from the 2019 Refinement to 2006 IPCC guidelines, we estimated CH4 emissions from global livestock at a spatial resolution of 0.083° (~9 km at the equator) during the period 1890-2019. We find that global CH4 emissions from livestock increased from 31.8 [26.5-37.1] (mean [minimum-maximum of 95% confidence interval) Tg CH4 yr-1 in 1890 to 131.7 [109.6-153.7] Tg CH4 yr-1 in 2019, a fourfold increase in the past 130years. The growth in global CH4 emissions mostly occurred after 1950 and was mainly attributed to the cattle sector. Our estimate shows faster growth in livestock CH4 emissions as compared to the previous Tier 1 estimates and is ~20% higher than the estimate from FAOSTAT for the year 2019. Regionally, South Asia, Brazil, North Africa, China, the United States, Western Europe, and Equatorial Africa shared the majority of the global emissions in the 2010s. South Asia, tropical Africa, and Brazil have dominated the growth in global CH4 emissions from livestock in the recent three decades. Changes in livestock CH4 emissions were primarily associated with changes in population and national income and were also affected by the policy, diet shifts, livestock productivity improvement, and international trade. The new geospatial information on the magnitude and trends of livestock CH4 emissions identifies emission hotspots and spatial-temporal patterns, which will help to guide meaningful CH4 mitigation practices in the livestock sector at both local and global scales.

    View details for DOI 10.1111/gcb.16280

    View details for PubMedID 35642457

  • Anthropogenic emission is the main contributor to the rise of atmospheric methane during 1993-2017. National science review Zhang, Z., Poulter, B., Knox, S., Stavert, A., McNicol, G., Fluet-Chouinard, E., Feinberg, A., Zhao, Y., Bousquet, P., Canadell, J. G., Ganesan, A., Hugelius, G., Hurtt, G., Jackson, R. B., Patra, P. K., Saunois, M., Höglund-Isaksson, L., Huang, C., Chatterjee, A., Li, X. 2022; 9 (5): nwab200


    Atmospheric methane (CH4) concentrations have shown a puzzling resumption in growth since 2007 following a period of stabilization from 2000 to 2006. Multiple hypotheses have been proposed to explain the temporal variations in CH4 growth, and attribute the rise of atmospheric CH4 either to increases in emissions from fossil fuel activities, agriculture and natural wetlands, or to a decrease in the atmospheric chemical sink. Here, we use a comprehensive ensemble of CH4 source estimates and isotopic δ13C-CH4 source signature data to show that the resumption of CH4 growth is most likely due to increased anthropogenic emissions. Our emission scenarios that have the fewest biases with respect to isotopic composition suggest that the agriculture, landfill and waste sectors were responsible for 53 ± 13% of the renewed growth over the period 2007-2017 compared to 2000-2006; industrial fossil fuel sources explained an additional 34 ± 24%, and wetland sources contributed the least at 13 ± 9%. The hypothesis that a large increase in emissions from natural wetlands drove the decrease in atmospheric δ13C-CH4 values cannot be reconciled with current process-based wetland CH4 models. This finding suggests the need for increased wetland measurements to better understand the contemporary and future role of wetlands in the rise of atmospheric methane and climate feedback. Our findings highlight the predominant role of anthropogenic activities in driving the growth of atmospheric CH4 concentrations.

    View details for DOI 10.1093/nsr/nwab200

    View details for PubMedID 35547958

    View details for PubMedCentralID PMC9084358

  • Global Carbon Budget 2021 EARTH SYSTEM SCIENCE DATA Friedlingstein, P., Jones, M. W., O'Sullivan, M., Andrew, R. M., Bakker, D. E., Hauck, J., Le Quere, C., Peters, G. P., Peters, W., Pongratz, J., Sitch, S., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S. R., Anthoni, P., Bates, N. R., Becker, M., Bellouin, N., Bopp, L., Chau, T., Chevallier, F., Chini, L. P., Cronin, M., Currie, K. I., Decharme, B., Djeutchouang, L. M., Dou, X., Evans, W., Feely, R. A., Feng, L., Gasser, T., Gilfillan, D., Gkritzalis, T., Grassi, G., Gregor, L., Gruber, N., Gurses, O., Harris, I., Houghton, R. A., Hurtt, G. C., Iida, Y., Ilyina, T., Luijkx, I. T., Jain, A., Jones, S. D., Kato, E., Kennedy, D., Klein Goldewijk, K., Knauer, J., Korsbakken, J., Kortzinger, A., Landschutzer, P., Lauvset, S. K., Lefevre, N., Lienert, S., Liu, J., Marland, G., McGuire, P. C., Melton, J. R., Munro, D. R., Nabel, J. S., Nakaoka, S., Niwa, Y., Ono, T., Pierrot, D., Poulter, B., Rehder, G., Resplandy, L., Robertson, E., Rodenbeck, C., Rosan, T. M., Schwinger, J., Schwingshackl, C., Seferian, R., Sutton, A. J., Sweeney, C., Tanhua, T., Tans, P. P., Tian, H., Tilbrook, B., Tubiello, F., van der Werf, G. R., Vuichard, N., Wada, C., Wanninkhof, R., Watson, A. J., Willis, D., Wiltshire, A. J., Yuan, W., Yue, C., Yue, X., Zaehle, S., Zeng, J. 2022; 14 (4): 1917-2005
  • Definitions and methods to estimate regional land carbon fluxes for the second phase of the REgional Carbon Cycle Assessment and Processes Project (RECCAP-2) GEOSCIENTIFIC MODEL DEVELOPMENT Ciais, P., Bastos, A., Chevallier, F., Lauerwald, R., Poulter, B., Canadell, P., Hugelius, G., Jackson, R. B., Jain, A., Jones, M., Kondo, M., Luijkx, I. T., Patra, P. K., Peters, W., Pongratz, J., Petrescu, A., Piao, S., Qiu, C., Von Randow, C., Regnier, P., Saunois, M., Scholes, R., Shvidenko, A., Tian, H., Yang, H., Wang, X., Zheng, B. 2022; 15 (3): 1289-1316
  • Methane and NOx Emissions from Natural Gas Stoves, Cooktops, and Ovens in Residential Homes. Environmental science & technology Lebel, E. D., Finnegan, C. J., Ouyang, Z., Jackson, R. B. 1800


    Natural gas stoves in >40 million U.S. residences release methane (CH4)─a potent greenhouse gas─through post-meter leaks and incomplete combustion. We quantified methane released in 53 homes during all phases of stove use: steady-state-off (appliance not in use), steady-state-on (during combustion), and transitory periods of ignition and extinguishment. We estimated that natural gas stoves emit 0.8-1.3% of the gas they use as unburned methane and that total U.S. stove emissions are 28.1 [95% confidence interval: 18.5, 41.2] Gg CH4 year-1. More than three-quarters of methane emissions we measured originated during steady-state-off. Using a 20-year timeframe for methane, annual methane emissions from all gas stoves in U.S. homes have a climate impact comparable to the annual carbon dioxide emissions of 500 000 cars. In addition to methane emissions, co-emitted health-damaging air pollutants such as nitrogen oxides (NOx) are released into home air and can trigger respiratory diseases. In 32 homes, we measured NOx (NO and NO2) emissions and found them to be linearly related to the amount of natural gas burned (r2 = 0.76; p ≪ 0.01). Emissions averaged 21.7 [20.5, 22.9] ng NOx J-1, comprised of 7.8 [7.1, 8.4] ng NO2 J-1 and 14.0 [12.8, 15.1] ng NO J-1. Our data suggest that families who don't use their range hoods or who have poor ventilation can surpass the 1-h national standard of NO2 (100 ppb) within a few minutes of stove usage, particularly in smaller kitchens.

    View details for DOI 10.1021/acs.est.1c04707

    View details for PubMedID 35081712

  • Contrasting responses of woody and grassland ecosystems to increased CO2 as water supply varies. Nature ecology & evolution Pan, Y., Jackson, R. B., Hollinger, D. Y., Phillips, O. L., Nowak, R. S., Norby, R. J., Oren, R., Reich, P. B., Luscher, A., Mueller, K. E., Owensby, C., Birdsey, R., Hom, J., Luo, Y. 1800


    Experiments show that elevated atmospheric CO2 (eCO2) often enhances plant photosynthesis and productivity, yet this effect varies substantially and may be climate sensitive. Understanding if, where and how water supply regulates CO2 enhancement is critical for projecting terrestrial responses to increasing atmospheric CO2 and climate change. Here, using data from 14 long-term ecosystem-scale CO2 experiments, we show that the eCO2 enhancement of annual aboveground net primary productivity is sensitive to annual precipitation and that this sensitivity differs between woody and grassland ecosystems. During wetter years, CO2 enhancement increases in woody ecosystems but declines in grass-dominated systems. Consistent with this difference, woody ecosystems can increase leaf area index in wetter years more effectively under eCO2 than can grassland ecosystems. Overall, and across different precipitation regimes, woody systems had markedly stronger CO2 enhancement (24%) than grasslands (13%). We developed an empirical relationship to quantify aboveground net primary productivity enhancement on the basis of changes in leaf area index, providing a new approach for evaluating eCO2 impacts on the productivity of terrestrial ecosystems.

    View details for DOI 10.1038/s41559-021-01642-6

    View details for PubMedID 35027723

  • Plant sizes and shapes above- and belowground and their interactions with climate. The New phytologist Tumber-Dávila, S. J., Schenk, H. J., Du, E., Jackson, R. B. 2022


    ●Although the above- and below-ground sizes and shapes of plants strongly influence plant competition, community structure, and plant-environment interactions, plant sizes and shapes remain poorly characterized across climate regimes. We investigated relationships among shoot and root system size and climate. ●We assembled and analyzed, to our knowledge, the largest global database describing the maximum rooting depth, lateral spread, and shoot size of terrestrial plants-more than doubling the Root Systems of Individual Plants (RSIP) database to 5,647 observations. ●Water availability and growth form greatly influence shoot size, and rooting depth is primarily influenced by temperature seasonality. Shoot size is the strongest predictor of lateral spread, with root system diameter being two times wider than shoot width on average for woody plants. ●Shoot size covaries strongly with rooting system size; however, the geometries of plants differ considerably across climates, with woody plants in more arid climates having shorter shoots, but deeper-narrower root systems. Additionally, estimates of the depth and lateral spread of plant root systems are likely underestimated at the global scale.

    View details for DOI 10.1111/nph.18031

    View details for PubMedID 35150454

  • Longevity Combating Climate Change in an Era of GENERATIONS Wang, C., Miller, J. G., Jackson, R. B., Carstensen, L. L. 2022; 46 (2)
  • Fire effects on the persistence of soil organic matter and long-term carbon storage NATURE GEOSCIENCE Pellegrini, A. A., Harden, J., Georgiou, K., Hemes, K. S., Malhotra, A., Nolan, C. J., Jackson, R. B. 2021
  • Rethinking the urban physical environment for century-long lives: from age-friendly to longevity-ready cities. Nature aging Wang, C., Huertas, D. S., Rowe, J. W., Finkelstein, R., Carstensen, L. L., Jackson, R. B. 2021; 1 (12): 1088-1095


    In response to increasing life expectancies and urbanization, initiatives for age-friendly cities seek to facilitate active and healthy aging by strengthening supports and services for older people. While laudable, these efforts typically neglect early-life exposures that influence long-term well-being. With a focus on the urban physical environment, we argue that longevity-ready cities can accomplish more than initiatives focused solely on old age. We review features of cities that cumulatively influence healthy aging and longevity, discuss the need for proactive interventions in a changing climate, and highlight inequities in the ambient physical environment, especially those encountered at early ages, that powerfully contribute to disparities in later life stages. Compared with strategies aimed largely at accommodating older populations, longevity-ready cities would aim to reduce the sources of disadvantages across the life course and simultaneously improve the well-being of older people.

    View details for DOI 10.1038/s43587-021-00140-5

    View details for PubMedID 35937461

  • Methane removal and the proportional reductions in surface temperature and ozone. Philosophical Transactions of the Royal Society A Abernethy, S., O’Connor, F. M., Jones, C. D., Jackson, R. B. 2021; 379: 20210104: 20210104


    Mitigating climate change requires a diverse portfolio of technologies and approaches, including negative emissions or removal of greenhouse gases. Previous literature focuses primarily on carbon dioxide removal, but methane removal may be an important complement to future efforts. Methane removal has at least two key benefits: reducing temperature more rapidly than carbon dioxide removal and improving air quality by reducing surface ozone concentration. While some removal technologies are being developed, modelling of their impacts is limited. Here, we conduct the first simulations using a methane emissions-driven Earth System Model to quantify the climate and air quality co-benefits of methane removal, including different rates and timings of removal. We define a novel metric, the effective cumulative removal, and use it to show that each effective petagram of methane removed causes a mean global surface temperature reduction of 0.21 ± 0.04°C and a mean global surface ozone reduction of 1.0 ± 0.2 parts per billion. Our results demonstrate the effectiveness of methane removal in delaying warming thresholds and reducing peak temperatures, and also allow for direct comparisons between the impacts of methane and carbon dioxide removal that could guide future research and climate policy. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 1)'.

    View details for DOI 10.1098/rsta.2021.0104

    View details for PubMedCentralID PMC8473947

  • Global mapping of crop-specific emission factors highlights hotspots of nitrous oxide mitigation. Nature food Cui, X., Zhou, F., Ciais, P., Davidson, E. A., Tubiello, F. N., Niu, X., Ju, X., Canadell, J. G., Bouwman, A. F., Jackson, R. B., Mueller, N. D., Zheng, X., Kanter, D. R., Tian, H., Adalibieke, W., Bo, Y., Wang, Q., Zhan, X., Zhu, D. 2021; 2 (11): 886-893


    Mitigating soil nitrous oxide (N2O) emissions is essential for staying below a 2 °C warming threshold. However, accurate assessments of mitigation potential are limited by uncertainty and variability in direct emission factors (EFs). To assess where and why EFs differ, we created high-resolution maps of crop-specific EFs based on 1,507 georeferenced field observations. Here, using a data-driven approach, we show that EFs vary by two orders of magnitude over space. At global and regional scales, such variation is primarily driven by climatic and edaphic factors rather than the well-recognized management practices. Combining spatially explicit EFs with N surplus information, we conclude that global mitigation potential without compromising crop production is 30% (95% confidence interval, 17-53%) of direct soil emissions of N2O, equivalent to the entire direct soil emissions of China and the United States combined. Two-thirds (65%) of the mitigation potential could be achieved on one-fifth of the global harvested area, mainly located in humid subtropical climates and across gleysols and acrisols. These findings highlight the value of a targeted policy approach on global hotspots that could deliver large N2O mitigation as well as environmental and food co-benefits.

    View details for DOI 10.1038/s43016-021-00384-9

    View details for PubMedID 37117501

    View details for PubMedCentralID 3306630

  • Global mapping of crop-specific emission factors highlights hotspots of nitrous oxide mitigation NATURE FOOD Cui, X., Zhou, F., Ciais, P., Davidson, E. A., Tubiello, F. N., Niu, X., Ju, X., Canadell, J. G., Bouwman, A. F., Jackson, R. B., Mueller, N. D., Zheng, X., Kanter, D. R., Tian, H., Adalibieke, W., Bo, Y., Wang, Q., Zhan, X., Zhu, D. 2021
  • Gap-filling eddy covariance methane fluxes: Comparison of machine learning model predictions and uncertainties at FLUXNET-CH4 wetlands AGRICULTURAL AND FOREST METEOROLOGY Irvin, J., Zhou, S., McNicol, G., Lu, F., Liu, V., Fluet-Chouinard, E., Ouyang, Z., Knox, S., Lucas-Moffat, A., Trotta, C., Papale, D., Vitale, D., Mammarella, I., Alekseychik, P., Aurela, M., Avati, A., Baldocchi, D., Bansal, S., Bohrer, G., Campbell, D., Chen, J., Chu, H., Dalmagro, H. J., Delwiche, K. B., Desai, A. R., Euskirchen, E., Feron, S., Goeckede, M., Heimann, M., Helbig, M., Helfter, C., Hemes, K. S., Hirano, T., Iwata, H., Jurasinski, G., Kalhori, A., Kondrich, A., Lai, D. F., Lohila, A., Malhotra, A., Merbold, L., Mitra, B., Ng, A., Nilsson, M. B., Noormets, A., Peichl, M., Rey-Sanchez, A., Richardson, A. D., Runkle, B. K., Schafer, K. R., Sonnentag, O., Stuart-Haentjens, E., Sturtevant, C., Ueyama, M., Valach, A. C., Vargas, R., Vourlitis, G. L., Ward, E. J., Wong, G., Zona, D., Alberto, M. R., Billesbach, D. P., Celis, G., Dolman, H., Friborg, T., Fuchs, K., Gogo, S., Gondwe, M. J., Goodrich, J. P., Gottschalk, P., Hortnagl, L., Jacotot, A., Koebsch, F., Kasak, K., Maier, R., Morin, T. H., Nemitz, E., Oechel, W. C., Oikawa, P. Y., Ono, K., Sachs, T., Sakabe, A., Schuur, E. A., Shortt, R., Sullivan, R. C., Szutu, D. J., Tuittila, E., Varlagin, A., Verfaillie, J. G., Wille, C., Windham-Myers, L., Poulter, B., Jackson, R. B. 2021; 308
  • Regional trends and drivers of the global methane budget. Global change biology Stavert, A. R., Saunois, M., Canadell, J. G., Poulter, B., Jackson, R. B., Regnier, P., Lauerwald, R., Raymond, P. A., Allen, G. H., Patra, P. K., Bergamaschi, P., Bousquet, P., Chandra, N., Ciais, P., Gustafson, A., Ishizawa, M., Ito, A., Kleinen, T., Maksyutov, S., McNorton, J., Melton, J. R., Muller, J., Niwa, Y., Peng, S., Riley, W. J., Segers, A., Tian, H., Tsuruta, A., Yin, Y., Zhang, Z., Zheng, B., Zhuang, Q. 2021


    The ongoing development of the Global Carbon Project (GCP) global methane (CH4 ) budget shows a continuation of increasing CH4 emissions and CH4 accumulation in the atmosphere over 2000-2017. Here we decompose the global budget into 19 regions (18 land and one oceanic) and five key source sectors to spatially attribute the observed global trends. A comparison of top-down (atmospheric and transport model-based) and bottom-up (inventory- and process model-based) CH4 emissions estimates demonstrates robust temporal trends with CH4 emissions increasing in 16 of the 19 regions. Five regions - China, Southeast Asia, USA, South Asia, and Brazil - account for > 40% of the global total emissions (their anthropogenic and natural sources together totalling > 270 Tg CH4 yr-1 in 2008-2017). Two of these regions, China and South Asia, emit predominantly anthropogenic emissions (> 75%) and together emit more than 25% of global anthropogenic emissions. China and the Middle East show the largest increases in total emission rates over the 2000 to 2017 period with regional emissions increasing by > 20%. In contrast, Europe and Korea & Japan, show a steady decline in CH4 emission rates, with total emissions decreasing by ~10% between 2000 and 2017. Coal mining, waste (predominantly solid waste disposal) and livestock (especially enteric fermentation) are dominant drivers of observed emissions increases while declines appear driven by a combination of waste and fossil emission reductions. As such, together these sectors present the greatest risks of further increasing the atmospheric CH4 burden and the greatest opportunities for greenhouse gas abatement.

    View details for DOI 10.1111/gcb.15901

    View details for PubMedID 34553464

  • Geochemical evidence for fugitive gas contamination and associated water quality changes in drinking-water wells from Parker County, Texas. The Science of the total environment Whyte, C. J., Vengosh, A., Warner, N. R., Jackson, R. B., Muehlenbachs, K., Schwartz, F. W., Darrah, T. H. 2021; 780: 146555


    Extensive development of horizontal drilling and hydraulic fracturing enhanced energy production but raised concerns about drinking-water quality in areas of shale-gas development. One particularly controversial case that has received significant public and scientific attention involves possible contamination of groundwater in the Trinity Aquifer in Parker County, Texas. Despite extensive work, the origin of natural gas in the Trinity Aquifer within this study area is an ongoing debate. Here, we present a comprehensive geochemical dataset collected across three sampling campaigns along with integration of previously published data. Data include major and trace ions, molecular gas compositions, compound-specific stable isotopes of hydrocarbons (delta13C-CH4, delta13C-C2H6, delta2H-CH4), dissolved inorganic carbon (delta13C-DIC), nitrogen (delta15N-N2), water (delta18O, delta2H, 3H), and noble gases (He, Ne, Ar), boron (delta11B) and strontium (87Sr/86Sr) isotopic compositions of water samples from 20 drinking-water wells from the Trinity Aquifer. The compendium of data confirms mixing between a deep, naturally occurring salt- (Cl >250mg/L) and hydrocarbon-rich groundwater with a low-salinity, shallower, and younger groundwater. Hydrocarbon gases display strong evidence for sulfate reduction-paired oxidation, in some cases followed by secondary methanogenesis. A subset of drinking-water wells contains elevated levels of hydrocarbons and depleted atmospherically-derived gas tracers, which is consistent with the introduction of fugitive thermogenic gas. We suggest that gas originating from the intermediate-depth Strawn Group ("Strawn") is flowing along the annulus of a Barnett Shale gas well, and is subsequently entering the shallow aquifer system. This interpretation is supported by the expansion in the number of affected drinking-water wells during our study period and the persistence of hydrocarbon levels over time. Our data suggest post-genetic secondary water quality changes occur following fugitive gas contamination, including sulfate reduction paired with hydrocarbon oxidation and secondary methanogenesis. Importantly, no evidence for upward migration of brine or natural gas associated with the Barnett Shale was identified.

    View details for DOI 10.1016/j.scitotenv.2021.146555

    View details for PubMedID 34030322

  • FLUXNET-CH4: a global, multi-ecosystem dataset and analysis of methane seasonality from freshwater wetlands EARTH SYSTEM SCIENCE DATA Delwiche, K. B., Knox, S., Malhotra, A., Fluet-Chouinard, E., McNicol, G., Feron, S., Ouyang, Z., Papale, D., Trotta, C., Canfora, E., Cheah, Y., Christianson, D., Alberto, M. R., Alekseychik, P., Aurela, M., Baldocchi, D., Bansal, S., Billesbach, D. P., Bohrer, G., Bracho, R., Buchmann, N., Campbell, D. I., Celis, G., Chen, J., Chen, W., Chu, H., Dalmagro, H. J., Dengel, S., Desai, A. R., Detto, M., Dolman, H., Eichelmann, E., Euskirchen, E., Famulari, D., Fuchs, K., Goeckede, M., Gogo, S., Gondwe, M. J., Goodrich, J. P., Gottschalk, P., Graham, S. L., Heimann, M., Helbig, M., Helfter, C., Hemes, K. S., Hirano, T., Hollinger, D., Hortnagl, L., Iwata, H., Jacotot, A., Jurasinski, G., Kang, M., Kasak, K., King, J., Klatt, J., Koebsch, F., Krauss, K. W., Lai, D. F., Lohila, A., Mammarella, I., Marchesini, L., Manca, G., Matthes, J., Maximov, T., Merbold, L., Mitra, B., Morin, T. H., Nemitz, E., Nilsson, M. B., Niu, S., Oechel, W. C., Oikawa, P. Y., Ono, K., Peichl, M., Peltola, O., Reba, M. L., Richardson, A. D., Riley, W., Runkle, B. K., Ryu, Y., Sachs, T., Sakabe, A., Sanchez, C., Schuur, E. A., Schafer, K. R., Sonnentag, O., Sparks, J. P., Stuart-Haentjens, E., Sturtevant, C., Sullivan, R. C., Szutu, D. J., Thom, J. E., Torn, M. S., Tuittila, E., Turner, J., Ueyama, M., Valach, A. C., Vargas, R., Varlagin, A., Vazquez-Lule, A., Verfaillie, J. G., Vesala, T., Vourlitis, G. L., Ward, E. J., Wille, C., Wohlfahrt, G., Wong, G., Zhang, Z., Zona, D., Windham-Myers, L., Poulter, B., Jackson, R. B. 2021; 13 (7): 3607-3689
  • Divergent controls of soil organic carbon between observations and process-based models BIOGEOCHEMISTRY Georgiou, K., Malhotra, A., Wieder, W. R., Ennis, J. H., Hartman, M. D., Sulman, B. N., Berhe, A., Grandy, A., Kyker-Snowman, E., Lajtha, K., Moore, J. M., Pierson, D., Jackson, R. B. 2021
  • Quantification of global and national nitrogen budgets for crop production NATURE FOOD Zhang, X., Zou, T., Lassaletta, L., Mueller, N. D., Tubiello, F. N., Lisk, M. D., Lu, C., Conant, R. T., Dorich, C. D., Gerber, J., Tian, H., Bruulsema, T., Maaz, T., Nishina, K., Bodirsky, B., Popp, A., Bouwman, L., Beusen, A., Chang, J., Havlik, P., Leclere, D., Canadell, J. G., Jackson, R. B., Heffer, P., Wanner, N., Zhang, W., Davidson, E. A. 2021
  • Quantification of global and national nitrogen budgets for crop production. Nature food Zhang, X., Zou, T., Lassaletta, L., Mueller, N. D., Tubiello, F. N., Lisk, M. D., Lu, C., Conant, R. T., Dorich, C. D., Gerber, J., Tian, H., Bruulsema, T., Maaz, T. M., Nishina, K., Bodirsky, B. L., Popp, A., Bouwman, L., Beusen, A., Chang, J., Havlík, P., Leclère, D., Canadell, J. G., Jackson, R. B., Heffer, P., Wanner, N., Zhang, W., Davidson, E. A. 2021; 2 (7): 529-540


    Input-output estimates of nitrogen on cropland are essential for improving nitrogen management and better understanding the global nitrogen cycle. Here, we compare 13 nitrogen budget datasets covering 115 countries and regions over 1961-2015. Although most datasets showed similar spatiotemporal patterns, some annual estimates varied widely among them, resulting in large ranges and uncertainty. In 2010, global medians (in TgN yr-1) and associated minimum-maximum ranges were 73 (64-84) for global harvested crop nitrogen; 161 (139-192) for total nitrogen inputs; 86 (68-97) for nitrogen surplus; and 46% (40-53%) for nitrogen use efficiency. Some of the most uncertain nitrogen budget terms by country showed ranges as large as their medians, revealing areas for improvement. A benchmark nitrogen budget dataset, derived from central tendencies of the original datasets, can be used in model comparisons and inform sustainable nitrogen management in food systems.

    View details for DOI 10.1038/s43016-021-00318-5

    View details for PubMedID 37117677

    View details for PubMedCentralID 3682748

  • Root traits explain plant species distributions along climatic gradients yet challenge the nature of ecological trade-offs. Nature ecology & evolution Laughlin, D. C., Mommer, L., Sabatini, F. M., Bruelheide, H., Kuyper, T. W., McCormack, M. L., Bergmann, J., Freschet, G. T., Guerrero-Ramirez, N. R., Iversen, C. M., Kattge, J., Meier, I. C., Poorter, H., Roumet, C., Semchenko, M., Sweeney, C. J., Valverde-Barrantes, O. J., van der Plas, F., van Ruijven, J., York, L. M., Aubin, I., Burge, O. R., Byun, C., Custerevska, R., Dengler, J., Forey, E., Guerin, G. R., Herault, B., Jackson, R. B., Karger, D. N., Lenoir, J., Lysenko, T., Meir, P., Niinemets, U., Ozinga, W. A., Penuelas, J., Reich, P. B., Schmidt, M., Schrodt, F., Velazquez, E., Weigelt, A. 2021


    Ecological theory is built on trade-offs, where trait differences among species evolved as adaptations to different environments. Trade-offs are often assumed to be bidirectional, where opposite ends of a gradient in trait values confer advantages in different environments. However, unidirectional benefits could be widespread if extreme trait values confer advantages at one end of an environmental gradient, whereas a wide range of trait values are equally beneficial at the other end. Here, we show that root traits explain species occurrences along broad gradients of temperature and water availability, but model predictions only resembled trade-offs in two out of 24 models. Forest species with low specific root length and high root tissue density (RTD) were more likely to occur in warm climates but species with high specific root length and low RTD were more likely to occur in cold climates. Unidirectional benefits were more prevalent than trade-offs: for example, species with large-diameter roots and high RTD were more commonly associated with dry climates, but species with the opposite trait values were not associated with wet climates. Directional selection for traits consistently occurred in cold or dry climates, whereas a diversity of root trait values were equally viable in warm or wet climates. Explicit integration of unidirectional benefits into ecological theory is needed to advance our understanding of the consequences of trait variation on species responses to environmental change.

    View details for DOI 10.1038/s41559-021-01471-7

    View details for PubMedID 34112996

  • Carbon analytics for net-zero emissions sustainable cities NATURE SUSTAINABILITY Ramaswami, A., Tong, K., Canadell, J. G., Jackson, R. B., Stokes, E., Dhakal, S., Finch, M., Jittrapirom, P., Singh, N., Yamagata, Y., Yewdall, E., Yona, L., Seto, K. C. 2021
  • Identifying dominant environmental predictors of freshwater wetland methane fluxes across diurnal to seasonal time scales. Global change biology Knox, S. H., Bansal, S., McNicol, G., Schafer, K., Sturtevant, C., Ueyama, M., Valach, A. C., Baldocchi, D., Delwiche, K., Desai, A. R., Euskirchen, E., Liu, J., Lohila, A., Malhotra, A., Melling, L., Riley, W., Runkle, B. R., Turner, J., Vargas, R., Zhu, Q., Alto, T., Fluet-Chouinard, E., Goeckede, M., Melton, J. R., Sonnentag, O., Vesala, T., Ward, E., Zhang, Z., Feron, S., Ouyang, Z., Alekseychik, P., Aurela, M., Bohrer, G., Campbell, D. I., Chen, J., Chu, H., Dalmagro, H. J., Goodrich, J. P., Gottschalk, P., Hirano, T., Iwata, H., Jurasinski, G., Kang, M., Koebsch, F., Mammarella, I., Nilsson, M. B., Ono, K., Peichl, M., Peltola, O., Ryu, Y., Sachs, T., Sakabe, A., Sparks, J., Tuittila, E., Vourlitis, G. L., Wong, G. X., Windham-Myers, L., Poulter, B., Jackson, R. B. 2021


    While wetlands are the largest natural source of methane (CH4 ) to the atmosphere, they represent a large source of uncertainty in the global CH4 budget due to the complex biogeochemical controls on CH4 dynamics. Here we present, to our knowledge, the first multi-site synthesis of how predictors of freshwater wetland CH4 fluxes (FCH4) vary across wetland types at diel, multiday (synoptic), and seasonal time scales. We used several statistical approaches (correlation analysis, generalized additive modeling, mutual information, random forests) in a wavelet-based multiresolution framework to assess the importance of environmental predictors, nonlinearities and lags on FCH4 across 23 eddy covariance sites. Seasonally, soil and air temperature were dominant predictors of FCH4 at sites with smaller seasonal variation in water table depth (WTD). In contrast, WTD was the dominant predictor for wetlands with smaller variations in temperature (e.g., seasonal tropical/subtropical wetlands). Changes in seasonal FCH4 lagged fluctuations in WTD by ~17 ± 11 days, and lagged air and soil temperature by median values of 8 ± 16 and 5 ± 15 days, respectively. Temperature and WTD were also dominant predictors at the multiday scale. Atmospheric pressure (PA) was another important multiday scale predictor for peat dominated sites, with drops in PA coinciding with synchronous releases of CH4 . At the diel scale, synchronous relationships with latent heat flux and vapor pressure deficit suggest that physical processes controlling evaporation and boundary layer mixing exert similar controls on CH4 volatilization, and suggest the influence of pressurized ventilation in aerenchymatous vegetation. In addition, 1-4 hour lagged relationships with ecosystem photosynthesis indicate recent carbon substrates, such as root exudates, may also control FCH4. By addressing issues of scale, asynchrony, and nonlinearity, this work improves understanding of the predictors and timing of wetland FCH4 that can inform future studies and models, and help constrain wetland CH4 emissions.

    View details for DOI 10.1111/gcb.15661

    View details for PubMedID 33914985

  • Orphaned oil and gas well stimulus-Maximizing economic and environmental benefits ELEMENTA-SCIENCE OF THE ANTHROPOCENE Kang, M., Brandt, A. R., Zheng, Z., Boutot, J., Yung, C., Peltz, A. S., Jackson, R. B. 2021; 9 (1)
  • Low-intensity frequent fires in coniferous forests transform soil organic matter in ways that may offset ecosystem carbon losses. Global change biology Pellegrini, A. F., Caprio, A. C., Georgiou, K., Finnegan, C., Hobbie, S. E., Hatten, J. A., Jackson, R. B. 2021


    The impact of shifting disturbance regimes on soil carbon (C) storage is a key uncertainty in global change research. Wildfires in coniferous forests are becoming more frequent in many regions, potentially causing large C emissions. Repeated low-intensity fires can mitigate wildfire severity, but repeated combustion may decrease soil C unless compensatory responses stabilize soil organic matter. Here we tested how 30 years of decadal prescribed burning affected C and nitrogen (N) in plants, detritus, and soils in coniferous forests in the Sierra Nevada mountains, USA. Tree basal area and litter stocks were resilient to fire, but fire reduced forest floor C by 77% (-36.4 MgC ha-1 ). In mineral soils, fire reduced C that was free from minerals by 41% (-4.4 MgC ha-1 ) but not C associated with minerals, and only in depths ≤ 5 cm. Fire also transformed the properties of remaining mineral soil organic matter by increasing the proportion of C in a pyrogenic form (from 3.2% to 7.5%) and associated with minerals (from 47% to 58%), suggesting the remaining soil C is more resistant to decomposition. Laboratory assays illustrated that fire reduced microbial CO2 respiration rates by 59% and the activity of eight extracellular enzymes that degrade cellulosic and aromatic compounds by 40-65%. Lower decomposition was correlated with lower inorganic N (-49%), especially ammonium, suggesting N availability is coupled with decomposition. The relative increase in forms of soil organic matter that are resistant to decay or stabilized onto mineral surfaces, and the associated decline in decomposition suggest that low-intensity fire can potentially promote mineral soil C storage in pools with long mean residence times in coniferous forests.

    View details for DOI 10.1111/gcb.15648

    View details for PubMedID 33884700

  • Plant rhizodeposition: A key factor for soil organic matter formation in stable fractions. Science advances Villarino, S. H., Pinto, P., Jackson, R. B., Pineiro, G. 2021; 7 (16)


    Soil organic carbon formation remains poorly understood despite its importance for human livelihoods. Uncertainties remain for the relative contributions of aboveground, root, and rhizodeposition inputs to particulate (POC) and mineral-associated (MAOC) organic carbon fractions. Combining a novel framework with isotope tracer studies, we quantified POC and MAOC formation efficiencies (% of C-inputs incorporated into each fraction). We found that rhizodeposition inputs have the highest MAOC formation efficiency (46%) as compared to roots (9%) or aboveground inputs (7%). In addition, rhizodeposition unexpectedly reduced POC formation, likely because it increased decomposition rates of new POC. Conversely, root biomass inputs have the highest POC formation efficiency (19%). Therefore, rhizodeposition and roots appear to play opposite but complementary roles for building MAOC and POC fractions.

    View details for DOI 10.1126/sciadv.abd3176

    View details for PubMedID 33853771

  • COVID-19 and Emissions: An Opportunity for Sustainable Global Health. European heart journal Rajagopalan, S., Jackson, R. B., Narula, J. 2021

    View details for DOI 10.1093/eurheartj/ehab156

    View details for PubMedID 33769528

  • Fossil CO2 emissions in the post-COVID-19 era NATURE CLIMATE CHANGE Le Quere, C., Peters, G. P., Friedlingstein, P., Andrew, R. M., Canadell, J. G., Davis, S. J., Jackson, R. B., Jones, M. W. 2021; 11 (3)
  • Decadal changes in fire frequencies shift tree communities and functional traits. Nature ecology & evolution Pellegrini, A. F., Refsland, T., Averill, C., Terrer, C., Staver, A. C., Brockway, D. G., Caprio, A., Clatterbuck, W., Coetsee, C., Haywood, J. D., Hobbie, S. E., Hoffmann, W. A., Kush, J., Lewis, T., Moser, W. K., Overby, S. T., Patterson, W. A., Peay, K. G., Reich, P. B., Ryan, C., Sayer, M. A., Scharenbroch, B. C., Schoennagel, T., Smith, G. R., Stephan, K., Swanston, C., Turner, M. G., Varner, J. M., Jackson, R. B. 2021


    Global change has resulted in chronic shifts in fire regimes. Variability in the sensitivity of tree communities to multi-decadal changes in fire regimes is critical to anticipating shifts in ecosystem structure and function, yet remains poorly understood. Here, we address the overall effects of fire on tree communities and the factors controlling their sensitivity in 29 sites that experienced multi-decadal alterations in fire frequencies in savanna and forest ecosystems across tropical and temperate regions. Fire had a strong overall effect on tree communities, with an average fire frequency (one fire every three years) reducing stem density by 48% and basal area by 53% after 50 years, relative to unburned plots. The largest changes occurred in savanna ecosystems and in sites with strong wet seasons or strong dry seasons, pointing to fire characteristics and species composition as important. Analyses of functional traits highlighted the impact of fire-driven changes in soil nutrients because frequent burning favoured trees with low biomass nitrogen and phosphorus content, and with more efficient nitrogen acquisition through ectomycorrhizal symbioses. Taken together, the response of trees to altered fire frequencies depends both on climatic and vegetation determinants of fire behaviour and tree growth, and the coupling between fire-driven nutrient losses and plant traits.

    View details for DOI 10.1038/s41559-021-01401-7

    View details for PubMedID 33633371

  • Reconnecting the Arts and Sciences BIOSCIENCE Jackson, R., Collins, S. 2021; 71 (2): 111
  • Multiple constraints cause positive and negative feedbacks limiting grassland soil CO2 efflux under CO2 enrichment. Proceedings of the National Academy of Sciences of the United States of America Fay, P. A., Hui, D., Jackson, R. B., Collins, H. P., Reichmann, L. G., Aspinwall, M. J., Jin, V. L., Khasanova, A. R., Heckman, R. W., Polley, H. W. 2021; 118 (2)


    Terrestrial ecosystems are increasingly enriched with resources such as atmospheric CO2 that limit ecosystem processes. The consequences for ecosystem carbon cycling depend on the feedbacks from other limiting resources and plant community change, which remain poorly understood for soil CO2 efflux, JCO2, a primary carbon flux from the biosphere to the atmosphere. We applied a unique CO2 enrichment gradient (250 to 500 L L-1) for eight years to grassland plant communities on soils from different landscape positions. We identified the trajectory of JCO2 responses and feedbacks from other resources, plant diversity [effective species richness, exp(H)], and community change (plant species turnover). We found linear increases in JCO2 on an alluvial sandy loam and a lowland clay soil, and an asymptotic increase on an upland silty clay soil. Structural equation modeling identified CO2 as the dominant limitation on JCO2 on the clay soil. In contrast with theory predicting limitation from a single limiting factor, the linear JCO2 response on the sandy loam was reinforced by positive feedbacks from aboveground net primary productivity and exp(H), while the asymptotic JCO2 response on the silty clay arose from a net negative feedback among exp(H), species turnover, and soil water potential. These findings support a multiple resource limitation view of the effects of global change drivers on grassland ecosystem carbon cycling and highlight a crucial role for positive or negative feedbacks between limiting resources and plant community structure. Incorporating these feedbacks will improve models of terrestrial carbon sequestration and ecosystem services.

    View details for DOI 10.1073/pnas.2008284117

    View details for PubMedID 33419921

  • Ecosystem Collapse and Climate Change Ecological Studies edited by Canadell, J. G., Jackson, R. B. Springer. 2021; 241
  • Ecosystem Collapse and Climate Change: An Introduction ECOSYSTEM COLLAPSE AND CLIMATE CHANGE Canadell, J. G., Jackson, R. B., Jackson, R. B., Canadell, J. G. 2021; 241: 1-9
  • Ecosystem Collapse and Climate Change Preface ECOSYSTEM COLLAPSE AND CLIMATE CHANGE Canadell, J. G., Jackson, R. B., Jackson, R. B., Canadell, J. G. 2021; 241: V-VI
  • Substantial hysteresis in emergent temperature sensitivity of global wetland CH4 emissions. Nature communications Chang, K., Riley, W. J., Knox, S. H., Jackson, R. B., McNicol, G., Poulter, B., Aurela, M., Baldocchi, D., Bansal, S., Bohrer, G., Campbell, D. I., Cescatti, A., Chu, H., Delwiche, K. B., Desai, A. R., Euskirchen, E., Friborg, T., Goeckede, M., Helbig, M., Hemes, K. S., Hirano, T., Iwata, H., Kang, M., Keenan, T., Krauss, K. W., Lohila, A., Mammarella, I., Mitra, B., Miyata, A., Nilsson, M. B., Noormets, A., Oechel, W. C., Papale, D., Peichl, M., Reba, M. L., Rinne, J., Runkle, B. R., Ryu, Y., Sachs, T., Schafer, K. V., Schmid, H. P., Shurpali, N., Sonnentag, O., Tang, A. C., Torn, M. S., Trotta, C., Tuittila, E., Ueyama, M., Vargas, R., Vesala, T., Windham-Myers, L., Zhang, Z., Zona, D. 2021; 12 (1): 2266


    Wetland methane (CH4) emissions ([Formula: see text]) are important in global carbon budgets and climate change assessments. Currently, [Formula: see text] projections rely on prescribed static temperature sensitivity that varies among biogeochemical models. Meta-analyses have proposed a consistent [Formula: see text] temperature dependence across spatial scales for use in models; however, site-level studies demonstrate that [Formula: see text] are often controlled by factors beyond temperature. Here, we evaluate the relationship between [Formula: see text] and temperature using observations from the FLUXNET-CH4 database. Measurements collected across the globe show substantial seasonal hysteresis between [Formula: see text] and temperature, suggesting larger [Formula: see text] sensitivity to temperature later in the frost-free season (about 77% of site-years). Results derived from a machine-learning model and several regression models highlight the importance of representing the large spatial and temporal variability within site-years and ecosystem types. Mechanistic advancements in biogeochemical model parameterization and detailed measurements in factors modulating CH4 production are thus needed to improve global CH4 budget assessments.

    View details for DOI 10.1038/s41467-021-22452-1

    View details for PubMedID 33859182

  • Global Carbon Budget 2020 EARTH SYSTEM SCIENCE DATA Friedlingstein, P., O'Sullivan, M., Jones, M. W., Andrew, R. M., Hauck, J., Olsen, A., Peters, G. P., Peters, W., Pongratz, J., Sitch, S., Le Quere, C., Canadell, J. G., Ciais, P., Jackson, R. B., Alin, S., Aragao, L. C., Arneth, A., Arora, V., Bates, N. R., Becker, M., Benoit-Cattin, A., Bittig, H. C., Bopp, L., Bultan, S., Chandra, N., Chevallier, F., Chini, L. P., Evans, W., Florentie, L., Forster, P. M., Gasser, T., Gehlen, M., Gilfillan, D., Gkritzalis, T., Gregor, L., Gruber, N., Harris, I., Hartung, K., Haverd, V., Houghton, R. A., Ilyina, T., Jain, A. K., Joetzjer, E., Kadono, K., Kato, E., Kitidis, V., Korsbakken, J., Landschutzer, P., Lefevre, N., Lenton, A., Lienert, S., Liu, Z., Lombardozzi, D., Marland, G., Metzl, N., Munro, D. R., Nabel, J. S., Nakaoka, S., Niwa, Y., O'Brien, K., Ono, T., Palmer, P. I., Pierrot, D., Poulter, B., Resplandy, L., Robertson, E., Rodenbeck, C., Schwinger, J., Seferian, R., Skjelvan, I., Smith, A. P., Sutton, A. J., Tanhua, T., Tans, P. P., Tian, H., Tilbrook, B., Van der Werf, G., Vuichard, N., Walker, A. P., Wanninkhof, R., Watson, A. J., Willis, D., Wiltshire, A. J., Yuan, W., Yue, X., Zaehle, S. 2020; 12 (4): 3269–3340
  • Opportunities and challenges in using remaining carbon budgets to guide climate policy NATURE GEOSCIENCE Matthews, H., Tokarska, K. B., Nicholls, Z. J., Rogelj, J., Canadell, J. G., Friedlingstein, P., Froelicher, T. L., Forster, P. M., Gillett, N. P., Ilyina, T., Jackson, R. B., Jones, C. D., Koven, C., Knutti, R., MacDougall, A. H., Meinshausen, M., Mengis, N., Seferian, R., Zickfeld, K. 2020; 13 (12): 769–79
  • Climate change extremes and photovoltaic power output NATURE SUSTAINABILITY Feron, S., Cordero, R. R., Damiani, A., Jackson, R. B. 2020
  • On the role of trend and variability in the hydroxyl radical (OH) in the global methane budget ATMOSPHERIC CHEMISTRY AND PHYSICS Zhao, Y., Saunois, M., Bousquet, P., Lin, X., Berchet, A., Hegglin, M. I., Canadell, J. G., Jackson, R. B., Deushi, M., Joeckel, P., Kinnison, D., Kirner, O., Strode, S., Tilmes, S., Dlugokencky, E. J., Zheng, B. 2020; 20 (21): 13011–22
  • Soil organic carbon accumulation rates on Mediterranean abandoned agricultural lands. The Science of the total environment Bell, S. M., Terrer, C., Barriocanal, C., Jackson, R. B., Rosell-Mele, A. 2020: 143535


    Secondary succession on abandoned agricultural lands can produce climate change mitigation cobenefits, such as soil carbon sequestration. However, the accumulation of soil organic carbon (SOC) in Mediterranean regions has been difficult to predict and is subject to multiple environmental and land management factors. Gains, losses, and no significant changes have all been reported. Here we compile chronosequence data (n=113) from published studies and new field sites to assess the response of SOC to agricultural land abandonment in peninsular Spain. We found an overall SOC accumulation rate of +2.3% yr-1 post-abandonment. SOC dynamics are highly variable and context-dependent. Minimal change occurs on abandoned cereal croplands compared to abandoned woody croplands (+4% yr-1). Accumulation is most prevalent within a Goldilocks climatic window of ~13-17°C and ~450-900mm precipitation, promoting >100% gains after three decades. Our secondary forest field sites accrued 40.8Mg C ha-1 (+172%) following abandonment and displayed greater SOC and N depth heterogeneity than natural forests demonstrating the long-lasting impact of agriculture. Although changes in regional climate and crop types abandoned will impact future carbon sequestration, abandonment remains a low-cost, long-term natural climate solution best incorporated in tandem with other multipurpose sustainable land management strategies.

    View details for DOI 10.1016/j.scitotenv.2020.143535

    View details for PubMedID 33190903

  • Peak grain forecasts for the US High Plains amid withering waters. Proceedings of the National Academy of Sciences of the United States of America Mrad, A., Katul, G. G., Levia, D. F., Guswa, A. J., Boyer, E. W., Bruen, M., Carlyle-Moses, D. E., Coyte, R., Creed, I. F., van de Giesen, N., Grasso, D., Hannah, D. M., Hudson, J. E., Humphrey, V., Iida, S., Jackson, R. B., Kumagai, T., Llorens, P., Michalzik, B., Nanko, K., Peters, C. A., Selker, J. S., Tetzlaff, D., Zalewski, M., Scanlon, B. R. 2020


    Irrigated agriculture contributes 40% of total global food production. In the US High Plains, which produces more than 50 million tons per year of grain, as much as 90% of irrigation originates from groundwater resources, including the Ogallala aquifer. In parts of the High Plains, groundwater resources are being depleted so rapidly that they are considered nonrenewable, compromising food security. When groundwater becomes scarce, groundwater withdrawals peak, causing a subsequent peak in crop production. Previous descriptions of finite natural resource depletion have utilized the Hubbert curve. By coupling the dynamics of groundwater pumping, recharge, and crop production, Hubbert-like curves emerge, responding to the linked variations in groundwater pumping and grain production. On a state level, this approach predicted when groundwater withdrawal and grain production peaked and the lag between them. The lags increased with the adoption of efficient irrigation practices and higher recharge rates. Results indicate that, in Texas, withdrawals peaked in 1966, followed by a peak in grain production 9 y later. After better irrigation technologies were adopted, the lag increased to 15 y from 1997 to 2012. In Kansas, where these technologies were employed concurrently with the rise of irrigated grain production, this lag was predicted to be 24 y starting in 1994. In Nebraska, grain production is projected to continue rising through 2050 because of high recharge rates. While Texas and Nebraska had equal irrigated output in 1975, by 2050, it is projected that Nebraska will have almost 10 times the groundwater-based production of Texas.

    View details for DOI 10.1073/pnas.2008383117

    View details for PubMedID 33020284

  • Homogenization of the terrestrial water cycle NATURE GEOSCIENCE Levia, D. F., Creed, I. F., Hannah, D. M., Nanko, K., Boyer, E. W., Carlyle-Moses, D. E., van de Giesen, N., Grasso, D., Guswa, A. J., Hudson, J. E., Hudson, S. A., Iida, S., Jackson, R. B., Katul, G. G., Kumagai, T., Llorens, P., Ribeiro, F., Pataki, D. E., Peters, C. A., Carretero, D., Selker, J. S., Tetzlaff, D., Zalewski, M., Bruen, M. 2020
  • The COVID-19 lockdowns: a window into the Earth System NATURE REVIEWS EARTH & ENVIRONMENT Diffenbaugh, N. S., Field, C. B., Appel, E. A., Azevedo, I. L., Baldocchi, D. D., Burke, M., Burney, J. A., Ciais, P., Davis, S. J., Fiore, A. M., Fletcher, S. M., Hertel, T. W., Horton, D. E., Hsiang, S. M., Jackson, R. B., Jin, X., Levi, M., Lobell, D. B., McKinley, G. A., Moore, F. C., Montgomery, A., Nadeau, K. C., Pataki, D. E., Randerson, J. T., Reichstein, M., Schnell, J. L., Seneviratne, S., Singh, D., Steiner, A. L., Wong-Parodi, G. 2020; 1 (9): 470-481
  • Moving toward Net-Zero Emissions Requires New Alliances for Carbon Dioxide Removal ONE EARTH Fuss, S., Canadell, J. G., Ciais, P., Jackson, R. B., Jones, C. D., Lyngfelt, A., Peters, G. P., Van Vuuren, D. P. 2020; 3 (2): 145-149
  • Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw. Proceedings of the National Academy of Sciences of the United States of America Hugelius, G., Loisel, J., Chadburn, S., Jackson, R. B., Jones, M., MacDonald, G., Marushchak, M., Olefeldt, D., Packalen, M., Siewert, M. B., Treat, C., Turetsky, M., Voigt, C., Yu, Z. 2020


    Northern peatlands have accumulated large stocks of organic carbon (C) and nitrogen (N), but their spatial distribution and vulnerability to climate warming remain uncertain. Here, we used machine-learning techniques with extensive peat core data (n > 7,000) to create observation-based maps of northern peatland C and N stocks, and to assess their response to warming and permafrost thaw. We estimate that northern peatlands cover 3.7 ± 0.5 million km2 and store 415 ± 150 Pg C and 10 ± 7 Pg N. Nearly half of the peatland area and peat C stocks are permafrost affected. Using modeled global warming stabilization scenarios (from 1.5 to 6 °C warming), we project that the current sink of atmospheric C (0.10 ± 0.02 Pg Cy-1) in northern peatlands will shift to a C source as 0.8 to 1.9 million km2 of permafrost-affected peatlands thaw. The projected thaw would cause peatland greenhouse gas emissions equal to 1% of anthropogenic radiative forcing in this century. The main forcing is from methane emissions (0.7 to 3 Pg cumulative CH4-C) with smaller carbon dioxide forcing (1 to 2 Pg CO2-C) and minor nitrous oxide losses. We project that initial CO2-C losses reverse after 200 y, as warming strengthens peatland C-sinks. We project substantial, but highly uncertain, additional losses of peat into fluvial systems of 10 to 30 Pg C and 0.4 to 0.9 Pg N. The combined gaseous and fluvial peatland C loss estimated here adds 30 to 50% onto previous estimates of permafrost-thaw C losses, with southern permafrost regions being the most vulnerable.

    View details for DOI 10.1073/pnas.1916387117

    View details for PubMedID 32778585

  • The Global Methane Budget 2000-2017 EARTH SYSTEM SCIENCE DATA Saunois, M., Stavert, A. R., Poulter, B., Bousquet, P., Canadell, J. G., Jackson, R. B., Raymond, P. A., Dlugokencky, E. J., Houweling, S., Patra, P. K., Ciais, P., Arora, V. K., Bastviken, D., Bergamaschi, P., Blake, D. R., Brailsford, G., Bruhwiler, L., Carlson, K. M., Carrol, M., Castaldi, S., Chandra, N., Crevoisier, C., Crill, P. M., Covey, K., Curry, C. L., Etiope, G., Frankenberg, C., Gedney, N., Hegglin, M., Hoglund-Isaksson, L., Hugelius, G., Ishizawa, M., Ito, A., Janssens-Maenhout, G., Jensen, K. M., Joos, F., Kleinen, T., Krummel, P. B., Langenfelds, R. L., Laruelle, G. G., Liu, L., Machida, T., Maksyutov, S., McDonald, K. C., McNorton, J., Miller, P. A., Melton, J. R., Morino, I., Muller, J., Murguia-Flores, F., Naik, V., Niwa, Y., Noce, S., Doherty, S. O., Parker, R. J., Peng, C., Peng, S., Peters, G. P., Prigent, C., Prinn, R., Ramonet, M., Regnier, P., Riley, W. J., Rosentreter, J. A., Segers, A., Simpson, I. J., Shi, H., Smith, S. J., Steele, L., Thornton, B. F., Tian, H., Tohjima, Y., Tubiello, F. N., Tsuruta, A., Viovy, N., Voulgarakis, A., Weber, T. S., van Weele, M., van der Werf, G. R., Weiss, R. F., Worthy, D., Wunch, D., Yin, Y., Yoshida, Y., Zhang, W., Zhang, Z., Zhao, Y., Zheng, B., Zhu, Q., Zhu, Q., Zhuang, Q. 2020; 12 (3): 1561–1623
  • Trees as Nature-Based Solutions ONE EARTH Griscom, B., Jackson, R. B., Konijnendijk, C., Luyssaert, S., Friess, D., Rudee, A., Seddon, N. 2020; 2 (5): 387-389
  • Repeated fire shifts carbon and nitrogen cycling by changing plant inputs and soil decomposition across ecosystems ECOLOGICAL MONOGRAPHS Pellegrini, A. A., Hobbie, S. E., Reich, P. B., Jumpponen, A., Brookshire, E., Caprio, A. C., Coetsee, C., Jackson, R. B. 2020

    View details for DOI 10.1002/ecm.1409

    View details for Web of Science ID 000529297800001

  • Advancing ecohydrology in the 21st century: A convergence of opportunities ECOHYDROLOGY Guswa, A. J., Tetzlaff, D., Selker, J. S., Carlyle-Moses, D. E., Boyer, E. W., Bruen, M., Cayuela, C., Creed, I. F., van de Giesen, N., Grasso, D., Hannah, D. M., Hudson, J. E., Hudson, S. A., Iida, S., Jackson, R. B., Katul, G. G., Kumagai, T., Llorens, P., Lopes Ribeiro, F., Michalzik, B., Nanko, K., Oster, C., Pataki, D. E., Peters, C. A., Rinaldo, A., Sanchez Carretero, D., Trifunovic, B., Zalewski, M., Haagsma, M., Levia, D. F. 2020

    View details for DOI 10.1002/eco.2208

    View details for Web of Science ID 000527873700001

  • Quantifying Methane Emissions from Natural Gas Water Heaters. Environmental science & technology Lebel, E. D., Lu, H. S., Speizer, S. A., Finnegan, C. J., Jackson, R. B. 2020


    Methane emissions from natural gas appliances remain the least characterized portion of the fossil-fuel supply chain. Here we examine water heaters from 64 northern California homes to (1) quantify methane emissions from natural gas leaks and incomplete combustion while off, turning on or off, and in steady-state operation from 35 homes; and (2) characterize daily usage patterns over 1-2 months per water heater to estimate activity factors from 46 homes. Individual tankless water heaters emitted 2390 [95% CI: 2250, 2540] g CH4 yr-1 on average, 0.93% [0.87%, 0.99%] of their natural gas consumed, primarily from on/off pulses. Storage water heaters emitted 1400 [1240, 1560] g CH4 yr-1 on average, 0.39% [0.34%, 0.43%] of their natural gas consumption. Despite higher methane emissions, tankless water heaters generate 29% less CO2e20 than storage water heaters because they use less energy to heat a unit of water. Scaling our measured emissions by the number of storage and tankless water heaters in the United States (56.8 and 1.2 million, respectively), water heaters overall emitted an estimated 82.3 [73.2, 91.5] Gg CH4 yr-1, 0.40% [0.35%, 0.44%] of all natural gas consumed by these appliances, comparable in percentage to the EPA's estimate of methane emissions from upstream natural gas production.

    View details for DOI 10.1021/acs.est.9b07189

    View details for PubMedID 32250600

  • Reply to: Practical constraints on atmospheric methane removal NATURE SUSTAINABILITY Jackson, R. B., Solomon, E. I., Canadell, J. G., Cargnello, M., Field, C. B., Abernethy, S. 2020
  • Global patterns of terrestrial nitrogen and phosphorus limitation NATURE GEOSCIENCE Du, E., Terrer, C., Pellegrini, A. A., Ahlstrom, A., van Lissa, C. J., Zhao, X., Xia, N., Wu, X., Jackson, R. B. 2020
  • Data-driven estimates of global nitrous oxide emissions from croplands NATIONAL SCIENCE REVIEW Wang, Q., Zhou, F., Shang, Z., Ciais, P., Winiwarter, W., Jackson, R. B., Tubiello, F. N., Janssens-Maenhout, G., Tian, H., Cui, X., Canadell, J. G., Piao, S., Tao, S. 2020; 7 (2): 441–52

    View details for DOI 10.1093/nsr/nwz087

    View details for Web of Science ID 000528014900024

  • Data-driven estimates of global nitrous oxide emissions from croplands. National science review Wang, Q., Zhou, F., Shang, Z., Ciais, P., Winiwarter, W., Jackson, R. B., Tubiello, F. N., Janssens-Maenhout, G., Tian, H., Cui, X., Canadell, J. G., Piao, S., Tao, S. 2020; 7 (2): 441-452


    Croplands are the single largest anthropogenic source of nitrous oxide (N2O) globally, yet their estimates remain difficult to verify when using Tier 1 and 3 methods of the Intergovernmental Panel on Climate Change (IPCC). Here, we re-evaluate global cropland-N2O emissions in 1961-2014, using N-rate-dependent emission factors (EFs) upscaled from 1206 field observations in 180 global distributed sites and high-resolution N inputs disaggregated from sub-national surveys covering 15593 administrative units. Our results confirm IPCC Tier 1 default EFs for upland crops in 1990-2014, but give a ∼15% lower EF in 1961-1989 and a ∼67% larger EF for paddy rice over the full period. Associated emissions (0.82 ± 0.34 Tg N yr-1) are probably one-quarter lower than IPCC Tier 1 global inventories but close to Tier 3 estimates. The use of survey-based gridded N-input data contributes 58% of this emission reduction, the rest being explained by the use of observation-based non-linear EFs. We conclude that upscaling N2O emissions from site-level observations to global croplands provides a new benchmark for constraining IPCC Tier 1 and 3 methods. The detailed spatial distribution of emission data is expected to inform advancement towards more realistic and effective mitigation pathways.

    View details for DOI 10.1093/nsr/nwz087

    View details for PubMedID 34692059

    View details for PubMedCentralID PMC8288841

  • Refining national greenhouse gas inventories. Ambio Yona, L., Cashore, B., Jackson, R. B., Ometto, J., Bradford, M. A. 2020


    The importance of greenhouse gas inventories cannot be overstated: the process of producing inventories informs strategies that governments will use to meet emissions reduction targets. The Intergovernmental Panel on Climate Change (IPCC) leads an effort to develop and refine internationally agreed upon methodologies for calculating and reporting greenhouse gas emissions and removals. We argue that these guidelines are not equipped to handle the task of developing national greenhouse gas inventories for most countries. Inventory guidelines are vital to implementing climate action, and we highlight opportunities to improve their timeliness and accuracy. Such reforms should provide the means to better understand and advance the progress countries are making toward their Paris commitments. Now is the time to consider challenges posed by the current process to develop the guidelines, and to avail the policy community of recent major advances in quantitative and expert synthesis to overhaul the process and thereby better equip multi-national efforts to limit climate change.

    View details for DOI 10.1007/s13280-019-01312-9

    View details for PubMedID 31981086

  • Increasing Anthropogenic Methane Emissions Arise Equally from Agricultural and Fossil Fuel Sources Environmental Research Letters Jackson, R. B., Saunois, M., Bousquet, P., Canadell, J. G., Poulter, B., et al 2020; in press
  • Agricultural acceleration of soil carbonate weathering. Global change biology Kim, J. H., Jobbágy, E. G., Richter, D. D., Trumbore, S. E., Jackson, R. B. 2020


    Soil carbonates (i.e., soil inorganic carbon or SIC) represent more than a quarter of the terrestrial carbon pool and are often considered to be relatively stable, with fluxes significant only on geologic timescales. However, given the importance of climatic water balance on SIC accumulation, we tested the hypothesis that increased soil water storage and transport resulting from cultivation may enhance dissolution of SIC, altering their local stock at decadal time scales. We compared SIC storage to 7.3 m depth in eight sites, each having paired plots of native vegetation and rain-fed croplands, and half the sites having additional irrigated cropland plots. Rain-fed and irrigated croplands had 328 and 730 Mg C/ha less SIC storage, respectively, compared to their native vegetation (grassland or woodland) pairs, and irrigated croplands had 402 Mg C/ha less than their rain-fed pairs (P<0.0001). SIC contents were negatively correlated with estimated groundwater recharge, suggesting that dissolution and leaching may be responsible for SIC losses observed. Under croplands, the remaining SIC had more modern radiocarbon and a δ13 C composition that was closer to crop inputs than under native vegetation, suggesting that cultivation has led to faster turnover and incorporation of recent crop carbon into the SIC pool (P<0.0001). The losses occurred just 30-100 years after land-use changes, indicating SIC stocks that were stable for millennia can rapidly adjust to increased soil water flows. Large SIC losses (194-242 Mg C/ha) also occurred below 4.9 m deep under irrigated croplands, with SIC losses lagging behind the downward-advancing wetting front by ~30 years, suggesting that even deep SIC were affected. These observations suggest that the vertical distribution of SIC in dry ecosystems is dynamic on decadal timescales, highlighting its potential role as a carbon sink or source to be examined in the context of land use and climate change.

    View details for DOI 10.1111/gcb.15207

    View details for PubMedID 32511819

  • The long and short of it: a review of the timescales of how fire affects soils using the pulse-press framework Advances in Ecological Research Pellegrini, A. F., Jackson, R. B. 2020; 62: 147-171
  • Advancing ecoydrology in the 21st century: a convergence of opportunities Ecohydrology Guzwa, A. J. 2020; 13:e2208
  • Influences of hydroxyl radicals (OH) on top-down estimates of the global and regional methane budgets Atmospheric Chemistry and Physics Zhao, Y., et al 2020; 20: 9525-9546

    View details for DOI 10.5194/acp-20-9525-2020

  • Moving towards net-zero emissions requires new alliances for carbon dioxide removal One Earth Fuss, S., et al 2020; 3: 145-149
  • Methane Emissions from Abandoned Oil and Gas Wells in California. Environmental science & technology Lebel, E. D., Lu, H. S., Vielstädte, L. n., Kang, M. n., Banner, P. n., Fischer, M. L., Jackson, R. B. 2020


    California hosts ∼124,000 abandoned and plugged (AP) oil and gas wells, ∼38,000 idle wells, and ∼63,000 active wells, whose methane (CH4) emissions remain largely unquantified at levels below ∼2 kg CH4 h-1. We sampled 121 wells using two methods: a rapid mobile plume integration method (detection ∼0.5 g CH4 h-1) and a more sensitive static flux chamber (detection ∼1 × 10-6 g CH4 h-1). We measured small but detectable methane emissions from 34 of 97 AP wells (mean emission: 0.286 g CH4 h-1). In contrast, we found emissions from 11 of 17 idle wells-which are not currently producing (mean: 35.4 g CH4 h-1)-4 of 6 active wells (mean: 189.7 g CH4 h-1), and one unplugged well-an open casing with no infrastructure present (10.9 g CH4 h-1). Our results support previous findings that emissions from plugged wells are low but are more substantial from idle wells. In addition, our smaller sample of active wells suggests that their reported emissions are consistent with previous studies and deserve further attention. Due to limited access, we could not measure wells in most major active oil and gas fields in California; therefore, we recommend additional data collection from all types of wells but especially active and idle wells.

    View details for DOI 10.1021/acs.est.0c05279

    View details for PubMedID 33125216

  • A comprehensive quantification of global nitrous oxide sources and sinks. Nature Tian, H. n., Xu, R. n., Canadell, J. G., Thompson, R. L., Winiwarter, W. n., Suntharalingam, P. n., Davidson, E. A., Ciais, P. n., Jackson, R. B., Janssens-Maenhout, G. n., Prather, M. J., Regnier, P. n., Pan, N. n., Pan, S. n., Peters, G. P., Shi, H. n., Tubiello, F. N., Zaehle, S. n., Zhou, F. n., Arneth, A. n., Battaglia, G. n., Berthet, S. n., Bopp, L. n., Bouwman, A. F., Buitenhuis, E. T., Chang, J. n., Chipperfield, M. P., Dangal, S. R., Dlugokencky, E. n., Elkins, J. W., Eyre, B. D., Fu, B. n., Hall, B. n., Ito, A. n., Joos, F. n., Krummel, P. B., Landolfi, A. n., Laruelle, G. G., Lauerwald, R. n., Li, W. n., Lienert, S. n., Maavara, T. n., MacLeod, M. n., Millet, D. B., Olin, S. n., Patra, P. K., Prinn, R. G., Raymond, P. A., Ruiz, D. J., van der Werf, G. R., Vuichard, N. n., Wang, J. n., Weiss, R. F., Wells, K. C., Wilson, C. n., Yang, J. n., Yao, Y. n. 2020; 586 (7828): 248–56


    Nitrous oxide (N2O), like carbon dioxide, is a long-lived greenhouse gas that accumulates in the atmosphere. Over the past 150 years, increasing atmospheric N2O concentrations have contributed to stratospheric ozone depletion1 and climate change2, with the current rate of increase estimated at 2 per cent per decade. Existing national inventories do not provide a full picture of N2O emissions, owing to their omission of natural sources and limitations in methodology for attributing anthropogenic sources. Here we present a global N2O inventory that incorporates both natural and anthropogenic sources and accounts for the interaction between nitrogen additions and the biochemical processes that control N2O emissions. We use bottom-up (inventory, statistical extrapolation of flux measurements, process-based land and ocean modelling) and top-down (atmospheric inversion) approaches to provide a comprehensive quantification of global N2O sources and sinks resulting from 21 natural and human sectors between 1980 and 2016. Global N2O emissions were 17.0 (minimum-maximum estimates: 12.2-23.5) teragrams of nitrogen per year (bottom-up) and 16.9 (15.9-17.7) teragrams of nitrogen per year (top-down) between 2007 and 2016. Global human-induced emissions, which are dominated by nitrogen additions to croplands, increased by 30% over the past four decades to 7.3 (4.2-11.4) teragrams of nitrogen per year. This increase was mainly responsible for the growth in the atmospheric burden. Our findings point to growing N2O emissions in emerging economies-particularly Brazil, China and India. Analysis of process-based model estimates reveals an emerging N2O-climate feedback resulting from interactions between nitrogen additions and climate change. The recent growth in N2O emissions exceeds some of the highest projected emission scenarios3,4, underscoring the urgency to mitigate N2O emissions.

    View details for DOI 10.1038/s41586-020-2780-0

    View details for PubMedID 33028999

  • Climate-driven risks to the climate mitigation potential of forests. Science (New York, N.Y.) Anderegg, W. R., Trugman, A. T., Badgley, G. n., Anderson, C. M., Bartuska, A. n., Ciais, P. n., Cullenward, D. n., Field, C. B., Freeman, J. n., Goetz, S. J., Hicke, J. A., Huntzinger, D. n., Jackson, R. B., Nickerson, J. n., Pacala, S. n., Randerson, J. T. 2020; 368 (6497)


    Forests have considerable potential to help mitigate human-caused climate change and provide society with many cobenefits. However, climate-driven risks may fundamentally compromise forest carbon sinks in the 21st century. Here, we synthesize the current understanding of climate-driven risks to forest stability from fire, drought, biotic agents, and other disturbances. We review how efforts to use forests as natural climate solutions presently consider and could more fully embrace current scientific knowledge to account for these climate-driven risks. Recent advances in vegetation physiology, disturbance ecology, mechanistic vegetation modeling, large-scale ecological observation networks, and remote sensing are improving current estimates and forecasts of the risks to forest stability. A more holistic understanding and quantification of such risks will help policy-makers and other stakeholders effectively use forests as natural climate solutions.

    View details for DOI 10.1126/science.aaz7005

    View details for PubMedID 32554569

  • Carbon dioxide emissions continue to grow amidst slowly emerging climate policies Nature Climate Change Peters, G. P., Andrew, R. M., Canadell, J. G., Friedlingstein, P., Jackson, R. B., Korsbakken , J., Le Quéré , C., Peregon, A. 2020; 10 (3-6)
  • Global and regional drivers of land-use emissions 1961-2017 Nature Hong, C., et al 2020; in press
  • Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement GLOBAL BIOGEOCHEMICAL CYCLES Ganesan, A. L., Schwietzke, S., Poulter, B., Arnold, T., Lan, X., Rigby, M., Vogel, F. R., van der Werf, G. R., Janssens-Maenhout, G., Boesch, H., Pandey, S., Manning, A. J., Jackson, R. B., Nisbet, E. G., Manning, M. 2019
  • Global Carbon Budget 2019 EARTH SYSTEM SCIENCE DATA Friedlingstein, P., Jones, M. W., O'Sullivan, M., Andrew, R. M., Hauck, J., Peters, G. P., Peters, W., Pongratz, J., Sitch, S., Le Quere, C., Bakker, D. E., Canadell, J. G., Ciais, P., Jackson, R. B., Anthoni, P., Barbero, L., Bastos, A., Bastrikov, V., Becker, M., Bopp, L., Buitenhuis, E., Chandra, N., Chevallier, F., Chini, L. P., Currie, K. I., Feely, R. A., Gehlen, M., Gilfillan, D., Gkritzalis, T., Goll, D. S., Gruber, N., Gutekunst, S., Harris, I., Haverd, V., Houghton, R. A., Hurtt, G., Ilyina, T., Jain, A. K., Joetzjer, E., Kaplan, J. O., Kato, E., Goldewijk, K., Korsbakken, J., Landschuetzer, P., Lauvset, S. K., Lefevre, N., Lenton, A., Lienert, S., Lombardozzi, D., Marland, G., McGuire, P. C., Melton, J. R., Metzl, N., Munro, D. R., Nabel, J. S., Nakaoka, S., Neill, C., Omar, A. M., Ono, T., Peregon, A., Pierrot, D., Poulter, B., Rehder, G., Resplandy, L., Robertson, E., Rodenbeck, C., Seferian, R., Schwinger, J., Smith, N., Tans, P. P., Tian, H., Tilbrook, B., Tubiello, F. N., van der Werf, G. R., Wiltshire, A. J., Zaehle, S. 2019; 11 (4): 1783–1838
  • Inter-model comparison of global hydroxyl radical (OH) distributions and their impact on atmospheric methane over the 2000-2016 period ATMOSPHERIC CHEMISTRY AND PHYSICS Zhao, Y., Saunois, M., Bousquet, P., Lin, X., Berchet, A., Hegglin, M. I., Canadell, J. G., Jackson, R. B., Hauglustaine, D. A., Szopa, S., Stavert, A. R., Abraham, N., Archibald, A. T., Bekki, S., Deushi, M., Joeckel, P., Josse, B., Kinnison, D., Kirner, O., Marecal, V., O'Connor, F. M., Plummer, D. A., Revell, L. E., Rozanov, E., Stenke, A., Strode, S., Tilmes, S., Dlugokencky, E. J., Zheng, B. 2019; 19 (21): 13701–23
  • Tunable laser-based detection of benzene using spectrally narrow absorption features APPLIED PHYSICS B-LASERS AND OPTICS Sur, R., Ding, Y., Jackson, R. B., Hanson, R. K. 2019; 125 (11)
  • Monthly gridded data product of northern wetland methane emissions based on upscaling eddy covariance observations EARTH SYSTEM SCIENCE DATA Peltola, O., Vesala, T., Gao, Y., Raty, O., Alekseychik, P., Aurela, M., Chojnicki, B., Desai, A. R., Dolman, A. J., Euskirchen, E. S., Friborg, T., Goeckede, M., Helbig, M., Humphreys, E., Jackson, R. B., Jocher, G., Joos, F., Klatt, J., Knox, S. H., Kowalska, N., Kutzbach, L., Lienert, S., Lohila, A., Mammarella, I., Nadeau, D. F., Nilsson, M. B., Oechel, W. C., Peichl, M., Pypker, T., Quinton, W., Rinne, J., Sachs, T., Samson, M., Schmid, H., Sonnentag, O., Wille, C., Zona, D., Aalto, T. 2019; 11 (3): 1263–89
  • Management intensification maintains wood production over multiple harvests in tropical Eucalyptus plantations ECOLOGICAL APPLICATIONS McMahon, D. E., Jackson, R. B. 2019; 29 (4)

    View details for DOI 10.1002/eap.1879

    View details for Web of Science ID 000474122100013

  • Flexibility and intensity of global water use NATURE SUSTAINABILITY Qin, Y., Mueller, N. D., Siebert, S., Jackson, R. B., AghaKouchak, A., Zimmerman, J. B., Tong, D., Hong, C., Davis, S. J. 2019; 2 (6): 515–23
  • CO2 enrichment and soil type additively regulate grassland productivity NEW PHYTOLOGIST Polley, H., Aspinwall, M. J., Collins, H. P., Gibson, A. E., Gill, R. A., Jackson, R. B., Jin, V. L., Khasanova, A. R., Reichmann, L. G., Fay, P. A. 2019; 222 (1): 183–92

    View details for DOI 10.1111/nph.15562

    View details for Web of Science ID 000459928400020

  • Ungulates mediate trade-offs between carbon storage and wildfire hazard in Mediterranean oak woodlands JOURNAL OF APPLIED ECOLOGY Lecomte, X., Caldeira, M. C., Catry, F. X., Fernandes, P. M., Jackson, R. B., Bugalho, M. N. 2019; 56 (3): 699–710
  • More than a decade of hydraulic fracturing and horizontal drilling research. Environmental science. Processes & impacts Plata, D. L., Jackson, R. B., Vengosh, A., Mouser, P. J. 2019

    View details for DOI 10.1039/c9em90004g

    View details for PubMedID 30753249

  • Global soil nitrous oxide emissions since the preindustrial era estimated by an ensemble of terrestrial biosphere models: Magnitude, attribution, and uncertainty GLOBAL CHANGE BIOLOGY Tian, H., Yang, J., Xu, R., Lu, C., Canadell, J. G., Davidson, E. A., Jackson, R. B., Arneth, A., Chang, J., Ciais, P., Gerber, S., Ito, A., Joos, F., Lienert, S., Messina, P., Olin, S., Pan, S., Peng, C., Saikawa, E., Thompson, R. L., Vuichard, N., Winiwarter, W., Zaehle, S., Zhang, B. 2019; 25 (2): 640–59

    View details for DOI 10.1111/gcb.14514

    View details for Web of Science ID 000456028900021

  • FLUXNET-CH4 synthesis activity: objectives, observations, and future directions Bulletin of the American Meteorological Society Knox, S. H., Jackson, R. B., Poulter, B., Gavin McNicol, G., Fluet-Chouinard, E., et al 2019; in press

    View details for DOI 10.1175/BAMS-D-18-0268.1

  • The landscape of soil carbon data: emerging questions, synergies and databases Progress in Physical Geography Malhotra, A., Todd-Brown, K., Nave, L. E., Batjes, N. H., Holmquist, J. R., Hoyt, A. M., Iversen, C. M., Jackson, R. B., Lajtha, K., Lawrence, C., Vindušková, O., Wieder, W., Williams, M., Hugelius, G., Harden, J. 2019

    View details for DOI 10.1177/0309133319873309

  • To Fight Climate Change, We Should Actually Add Carbon Dioxide to the Atmosphere Scientific American Jackson, R. B., Canadell, J. G. 2019; August
  • TRY plant trait database - enhanced coverage and open access Global Change Biology Kattge, J., et al 2019

    View details for DOI 10.1111/gcb.14904

  • Deep groundwater quality in the southwestern United States Environmental Research Letters Kang, M., Ayers, J. E., Jackson, R. B. 2019; 14: 034004

    View details for DOI 10.1088/1748-9326/aae93c

  • A first record of bulk atmospheric deposition patterns of major ions in southern South America. Biogeochemistry Carnelos, D. A., Portela, S. I., Jobbágy, E. G., Jackson, R. B., Di Bella, C., et al 2019; 144: 261-271
  • Soil nutrient stocks are maintained over multiple rotations in Brazilian Eucalyptus plantations Forest Ecology and Management McMahon, D. E., Vergütz, L., Valadares, S. V., Ribeiro da Silva, I., Jackson, R. B. 2019; 448: 364-375
  • Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass. Nature Climate Change Terrer, C., Jackson, R. B., Prentice, I. C., Keenan, T. F., Kaiser, C., et al 2019; 9: 684–689
  • Traditional plant functional groups explain variation in economic but not size‐related traits across the tundra biome Global Ecology and Biogeography Thomas, H. J., et al 2019; 28 (78-95)

    View details for DOI 10.1111/geb.12783

  • CO2 enrichment and soil type additively regulate grassland productivity. The New phytologist Polley, H. W., Aspinwall, M. J., Collins, H. P., Gibson, A. E., Gill, R. A., Jackson, R. B., Jin, V. L., Khasanova, A. R., Reichmann, L. G., Fay, P. A. 2018


    Atmospheric CO2 enrichment usually increases aboveground productivity (ANPP) of grassland vegetation, but the magnitude of the ANPP-CO2 response differs among ecosystems. Soil properties affect ANPP via multiple mechanisms and vary over topographic to geographic gradients, but have received little attention as potential modifiers of the ANPP-CO2 response. We assessed effects of three soil types, sandy loam, silty clay, and clay, on the ANPP response of perennial C3 /C4 grassland communities to a subambient to elevated CO2 gradient over 10 years in Texas, USA. We predicted an interactive, rather than additive, effect of CO2 and soil type on ANPP. Contrary to prediction, CO2 and soil additively influenced grassland ANPP. Increasing CO2 by 250 muL L-1 increased ANPP by 170 g m-2 across soil types. Increased clay content from 10% to 50% among soils reduced ANPP by 50 g m-2 . CO2 enrichment increased ANPP via a predominant direct effect accompanied by a smaller indirect effect mediated by successional shift to increased dominance of the C4 tallgrass Sorghastrum nutans. Our results indicate a large, positive influence of CO2 enrichment on grassland productivity that resulted from direct physiological benefits of CO2 augmented by species succession and was expressed similarly across soils of differing physical properties. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30367488

  • Projected drought effects on the demography of Ashe juniper populations inferred from remote measurements of tree canopies PLANT ECOLOGY Polley, H., Johnson, D. M., Jackson, R. B. 2018; 219 (10): 1259–67
  • Accounting for landscape heterogeneity improves spatial predictions of tree vulnerability to drought. The New phytologist Schwantes, A. M., Parolari, A. J., Swenson, J. J., Johnson, D. M., Domec, J., Jackson, R. B., Pelak, N., Porporato, A. 2018


    As climate change continues, forest vulnerability to droughts and heatwaves is increasing, but vulnerability varies regionally and locally through landscape position. Also, most models used in forecasting forest responses to heat and drought do not incorporate relevant spatial processes. In order to improve spatial predictions of tree vulnerability, we employed a nonlinear stochastic model of soil moisture dynamics accounting for landscape differences in aspect, topography and soils. Across a watershed in central Texas we modeled dynamic water stress for a dominant tree species, Juniperus ashei, and projected future dynamic water stress through the 21st century. Modeled dynamic water stress tracked spatial patterns of remotely sensed drought-induced canopy loss. Accuracy in predicting drought-impacted stands increased from 60%, accounting for spatially variable soil conditions, to 72% when also including lateral redistribution of water and radiation/temperature effects attributable to aspect. Our analysis also suggests that dynamic water stress will increase through the 21st century, with trees persisting at only selected microsites. Favorable microsites/refugia may exist across a landscape where trees can persist; however, if future droughts are too severe, the buffering capacity of an heterogeneous landscape could be overwhelmed. Incorporating spatial data will improve projections of future tree water stress and identification of potential resilient refugia.

    View details for PubMedID 29974958

  • Auto Mileage Rollback Is a Sick Idea The current EPA rules are better for our wallets and our health SCIENTIFIC AMERICAN Jackson, R. 2018; 319 (1): 12
  • THE GLOBAL N2O MODEL INTERCOMPARISON PROJECT BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY Tian, H., Yang, J., Lu, C., Xu, R., Canadell, J. G., Jackson, R. B., Arneth, A., Chang, J., Chen, G., Ciais, P., Gerber, S., Ito, A., Huang, Y., Joos, F., Lienert, S., Messina, P., Olin, S., Pan, S., Peng, C., Saikawa, E., Thompson, R. L., Vuichard, N., Winiwarter, W., Zaehle, S., Zhang, B., Zhang, K., Zhu, Q. 2018; 99 (6): 1231–52
  • REPLY TO XI ET AL.: Water table fluctuation is well recognized and discussed in our study PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Fan, Y., Miguez-Macho, G., Jobbagy, E. G., Jackson, R. B., Otero-Casal, C. 2018; 115 (17): E3865

    View details for PubMedID 29666223

  • Flowering in grassland predicted by CO2 and resource effects on species aboveground biomass GLOBAL CHANGE BIOLOGY Fay, P. A., Aspinwall, M. J., Collins, H. P., Gibson, A. E., Gill, R., Jackson, R. B., Jin, V. L., Khasanova, A. R., Reichmann, L., Polley, H. 2018; 24 (4): 1771–81


    Continuing enrichment of atmospheric CO2 may change plant community composition, in part by altering the availability of other limiting resources including soil water, nutrients, or light. The combined effects of CO2 enrichment and altered resource availability on species flowering remain poorly understood. We quantified flowering culm and ramet production and biomass allocation to flowering culms/ramets for 10 years in C4 -dominated grassland communities on contrasting soils along a CO2 concentration gradient spanning pre-industrial to expected mid-21st century levels (250-500 μl/L). CO2 enrichment explained up to 77% of the variation in flowering culm count across soils for three of the five species, and was correlated with flowering culm count on at least one soil for four of five species. In contrast, allocation to flowering culms was only weakly correlated with CO2 enrichment for two species. Flowering culm counts were strongly correlated with species aboveground biomass (AGB; R2  = .34-.74), a measure of species abundance. CO2 enrichment also increased soil moisture and decreased light levels within the canopy but did not affect soil inorganic nitrogen availability. Structural equation models fit across the soils suggested species-specific controls on flowering in two general forms: (1) CO2 effects on flowering culm count mediated by canopy light level and relative species AGB (species AGB/total AGB) or by soil moisture effects on flowering culm count; (2) effects of canopy light level or soil inorganic nitrogen on flowering and/or relative species AGB, but with no significant CO2 effect. Understanding the heterogeneity in species responses to CO2 enrichment in plant communities across soils in edaphically variable landscapes is critical to predict CO2 effects on flowering and other plant fitness components, and species potential to adapt to future environmental changes.

    View details for PubMedID 29282824

  • REPLY TO PIERRET AND LACOMBE: Global controls on maximum rooting depths remain important PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Fan, Y., Miguez-Macho, G., Jobbagy, E. G., Jackson, R. B., Otero-Casal, C. 2018; 115 (12): E2671–E2672

    View details for PubMedID 29487217

  • Global Carbon Budget 2017 EARTH SYSTEM SCIENCE DATA Le Quere, C., Andrew, R. M., Friedlingstein, P., Sitch, S., Pongratz, J., Manning, A. C., Korsbakken, J., Peters, G. P., Canadell, J. G., Jackson, R. B., Boden, T. A., Tans, P. P., Andrews, O. D., Arora, V. K., Bakker, D. E., Barbero, L., Becker, M., Betts, R. A., Bopp, L., Chevallier, F., Chini, L. P., Ciais, P., Cosca, C. E., Cross, J., Currie, K., Gasser, T., Harris, I., Hauck, J., Haverd, V., Houghton, R. A., Hunt, C. W., Hurtt, G., Ilyina, T., Jain, A. K., Kato, E., Kautz, M., Keeling, R. F., Goldewijk, K., Koertzinger, A., Landschuetzer, P., Lefevre, N., Lenton, A., Lienert, S., Lima, I., Lombardozzi, D., Metzl, N., Millero, F., Monteiro, P. S., Munro, D. R., Nabel, J. S., Nakaoka, S., Nojiri, Y., Padin, X., Peregon, A., Pfeil, B., Pierrot, D., Poulter, B., Rehder, G., Reimer, J., Roedenbeck, C., Schwinger, J., Seferian, R., Skjelvan, I., Stocker, B. D., Tian, H., Tilbrook, B., Tubiello, F. N., van der Laan-Luijkx, I. T., van der Werf, G. R., van Heuven, S., Viovy, N., Vuichard, N., Walker, A. P., Watson, A. J., Wiltshire, A. J., Zaehle, S., Zhu, D. 2018; 10 (1): 405–48
  • Co-occurring woody species have diverse hydraulic strategies and mortality rates during an extreme drought PLANT CELL AND ENVIRONMENT Johnson, D. M., Domec, J., Berry, Z., Schwantes, A. M., McCulloh, K. A., Woodruff, D. R., Polley, H., Wortemann, R., Swenson, J. J., Mackay, D., McDowell, N. G., Jackson, R. B. 2018; 41 (3): 576–88


    From 2011 to 2013, Texas experienced its worst drought in recorded history. This event provided a unique natural experiment to assess species-specific responses to extreme drought and mortality of four co-occurring woody species: Quercus fusiformis, Diospyros texana, Prosopis glandulosa, and Juniperus ashei. We examined hypothesized mechanisms that could promote these species' diverse mortality patterns using postdrought measurements on surviving trees coupled to retrospective process modelling. The species exhibited a wide range of gas exchange responses, hydraulic strategies, and mortality rates. Multiple proposed indices of mortality mechanisms were inconsistent with the observed mortality patterns across species, including measures of the degree of iso/anisohydry, photosynthesis, carbohydrate depletion, and hydraulic safety margins. Large losses of spring and summer whole-tree conductance (driven by belowground losses of conductance) and shallower rooting depths were associated with species that exhibited greater mortality. Based on this retrospective analysis, we suggest that species more vulnerable to drought were more likely to have succumbed to hydraulic failure belowground.

    View details for PubMedID 29314069

  • Structural and Hydrogeological Controls on Hydrocarbon and Brine Migration into Drinking Water Aquifers in Southern New York GROUNDWATER Kreuzer, R. L., Darrah, T. H., Grove, B. S., Moore, M. T., Warner, N. R., Eymold, W. K., Whyte, C. J., Mitra, G., Jackson, R. B., Vengosh, A., Poreda, R. J. 2018; 56 (2): 225–44


    Environmental concerns regarding the potential for drinking water contamination in shallow aquifers have accompanied unconventional energy development in the northern Appalachian Basin. These activities have also raised several critical questions about the hydrogeological parameters that control the naturally occurring presence and migration of hydrocarbon gases in shallow aquifers within petroliferous basins. To interrogate these factors, we analyzed the noble gas, dissolved ion, and hydrocarbon gas (molecular and isotopic composition) geochemistry of 98 groundwater samples from south-central New York. All samples were collected ≫1km from unconventional drilling activities and sample locations were intentionally targeted based on their proximity to various types of documented fault systems. In agreement with studies from other petroliferous basins, our results show significant correlations between elevated levels of radiogenic [4 He], thermogenic [CH4 ], and dissolved ions (e.g., Cl, Br, Sr, Ba). In combination, our data suggest that faults have facilitated the transport of exogenous hydrocarbon-rich brines from Devonian source rocks into overlying Upper Devonian aquifer lithologies over geologic time. These data conflict with previous reports, which conclude that hydrodynamic focusing regulates the occurrence of methane and salt in shallow aquifers and leads to elevated levels of these species in restricted flow zones within valley bottoms. Instead, our data suggest that faults in Paleozoic rocks play a fundamental role in gas and brine transport from depth, regulate the distribution of their occurrence in shallow aquifers, and influence the geochemistry of shallow groundwater in this petroliferous basin.

    View details for PubMedID 29409144

  • Networking our science to characterize the state, vulnerabilities, and management opportunities of soil organic matter. Global change biology Harden, J. W., Hugelius, G., Ahlström, A., Blankinship, J. C., Bond-Lamberty, B., Lawrence, C. R., Loisel, J., Malhotra, A., Jackson, R. B., Ogle, S., Phillips, C., Ryals, R., Todd-Brown, K., Vargas, R., Vergara, S. E., Cotrufo, M. F., Keiluweit, M., Heckman, K. A., Crow, S. E., Silver, W. L., DeLonge, M., Nave, L. E. 2018; 24 (2): e705-e718


    Soil organic matter (SOM) supports the Earth's ability to sustain terrestrial ecosystems, provide food and fiber, and retains the largest pool of actively cycling carbon. Over 75% of the soil organic carbon (SOC) in the top meter of soil is directly affected by human land use. Large land areas have lost SOC as a result of land use practices, yet there are compensatory opportunities to enhance productivity and SOC storage in degraded lands through improved management practices. Large areas with and without intentional management are also being subjected to rapid changes in climate, making many SOC stocks vulnerable to losses by decomposition or disturbance. In order to quantify potential SOC losses or sequestration at field, regional, and global scales, measurements for detecting changes in SOC are needed. Such measurements and soil-management best practices should be based on well established and emerging scientific understanding of processes of C stabilization and destabilization over various timescales, soil types, and spatial scales. As newly engaged members of the International Soil Carbon Network, we have identified gaps in data, modeling, and communication that underscore the need for an open, shared network to frame and guide the study of SOM and SOC and their management for sustained production and climate regulation.

    View details for DOI 10.1111/gcb.13896

    View details for PubMedID 28981192

  • The need to protect fresh and brackish groundwater resources during unconventional oil and gas development Current Opinion in Environmental Science & Health DiGiulio, D. C., Shonkoff, S. B., Jackson, R. B. 2018; 3: 1-7
  • Global energy growth is outpacing decarbonization Environmental Research Letters Jackson, R. B., Le Quéré, C., Andrew, R. M., Canadell, J. G., Korsbakken, J. I., Liu, Z., Peters, G. P., Zheng, B. 2018; 13: 120401

    View details for DOI 10.1088/1748-9326/aaf303

  • Aerial inter-year comparison and quantification of methane emissions persistence in the Bakken formation of North Dakota, USA. Environmental science & technology Englander, J. G., Brandt, A. R., Conley, S. n., Lyon, D. R., Jackson, R. B. 2018


    We performed an infrared optical gas imaging (OGI) survey by helicopter of hydrocarbon emissions in the Bakken formation of North Dakota. One year after an earlier survey of 682 well pads in September of 2014, the same helicopter crew re-surveyed 353 well pads in 2015 to examine the persistence of emissions. Twenty-one newly producing well pads were added in the same sampling blocks. An instrumented aircraft was also used to quantify emissions from 33 plumes identified by aerial OGI. Wellpads emitting methane and ethane in 2014 were far more likely to be emitting in 2015 than would expected by chance; Monte Carlo simulations suggest >5σ deviation (P<0.0001) from random assignment of detectable emissions between survey years. Scaled-up using basin-wide leakage estimates, the emissions quantified by aircraft are sufficient to explain previously observed basin-wide emissions of methane and ethane.

    View details for PubMedID 29989804

  • Evaluating Environmental Governance along Cross-Border Electricity Supply Chains with Policy-Informed Life Cycle Assessment: The California-Mexico Energy Exchange. Environmental science & technology Bolorinos, J. n., Ajami, N. K., Muñoz Meléndez, G. n., Jackson, R. B. 2018


    This paper presents a "policy-informed" life cycle assessment of a cross-border electricity supply chain that links the impact of each unit process to its governing policy framework. An assessment method is developed and applied to the California-Mexico energy exchange as a unique case study. CO2-equivalent emissions impacts, water withdrawals, and air quality impacts associated with California's imports of electricity from Mexican combined-cycle facilities fueled by natural gas from the U.S. Southwest are estimated, and U.S. and Mexican state and federal environmental regulations are examined to assess well-to-wire consistency of energy policies. Results indicate most of the water withdrawn per kWh exported to California occurs in Baja California, most of the air quality impacts accrue in the U.S. Southwest, and emissions of CO2-equivalents are more evenly divided between the two regions. California energy policy design addresses generation-phase CO2 emissions, but not upstream CO2-eq emissions of methane during the fuel cycle. Water and air quality impacts are not regulated consistently due to varying U.S. state policies and a lack of stringent federal regulation of unconventional gas development. Considering local impacts and the regulatory context where they occur provides essential qualitative information for functional-unit-based measures of life cycle impact and is necessary for a more complete environmental impact assessment.

    View details for PubMedID 29630347

  • Measuring canopy loss and climatic thresholds from an extreme drought along a fivefold precipitation gradient across Texas. Global change biology Schwantes, A. M., Swenson, J. J., González-Roglich, M., Johnson, D. M., Domec, J. C., Jackson, R. B. 2017; 23 (12): 5120-5135


    Globally, trees are increasingly dying from extreme drought, a trend that is expected to increase with climate change. Loss of trees has significant ecological, biophysical, and biogeochemical consequences. In 2011, a record drought caused widespread tree mortality in Texas. Using remotely sensed imagery, we quantified canopy loss during and after the drought across the state at 30-m spatial resolution, from the eastern pine/hardwood forests to the western shrublands, a region that includes the boundaries of many species ranges. Canopy loss observations in ~200 multitemporal fine-scale orthophotos (1-m) were used to train coarser Landsat imagery (30-m) to create 30-m binary statewide canopy loss maps. We found that canopy loss occurred across all major ecoregions of Texas, with an average loss of 9.5%. The drought had the highest impact in post oak woodlands, pinyon-juniper shrublands and Ashe juniper woodlands. Focusing on a 100-km by ~1,000-km transect spanning the State's fivefold east-west precipitation gradient (~1,500 to ~300 mm), we compared spatially explicit 2011 climatic anomalies to our canopy loss maps. Much of the canopy loss occurred in areas that passed specific climatic thresholds: warm season anomalies in mean temperature (+1.6°C) and vapor pressure deficit (VPD, +0.66 kPa), annual percent deviation in precipitation (-38%), and 2011 difference between precipitation and potential evapotranspiration (-1,206 mm). Although similarly low precipitation occurred during the landmark 1950s drought, the VPD and temperature anomalies observed in 2011 were even greater. Furthermore, future climate data under the representative concentration pathway 8.5 trajectory project that average values will surpass the 2011 VPD anomaly during the 2070-2099 period and the temperature anomaly during the 2040-2099 period. Identifying vulnerable ecological systems to drought stress and climate thresholds associated with canopy loss will aid in predicting how forests will respond to a changing climate and how ecological landscapes will change in the near term.

    View details for DOI 10.1111/gcb.13775

    View details for PubMedID 28649768

  • Hydrologic regulation of plant rooting depth. Proceedings of the National Academy of Sciences of the United States of America Fan, Y., Miguez-Macho, G., Jobbágy, E. G., Jackson, R. B., Otero-Casal, C. 2017; 114 (40): 10572-10577


    Plant rooting depth affects ecosystem resilience to environmental stress such as drought. Deep roots connect deep soil/groundwater to the atmosphere, thus influencing the hydrologic cycle and climate. Deep roots enhance bedrock weathering, thus regulating the long-term carbon cycle. However, we know little about how deep roots go and why. Here, we present a global synthesis of 2,200 root observations of >1,000 species along biotic (life form, genus) and abiotic (precipitation, soil, drainage) gradients. Results reveal strong sensitivities of rooting depth to local soil water profiles determined by precipitation infiltration depth from the top (reflecting climate and soil), and groundwater table depth from below (reflecting topography-driven land drainage). In well-drained uplands, rooting depth follows infiltration depth; in waterlogged lowlands, roots stay shallow, avoiding oxygen stress below the water table; in between, high productivity and drought can send roots many meters down to the groundwater capillary fringe. This framework explains the contrasting rooting depths observed under the same climate for the same species but at distinct topographic positions. We assess the global significance of these hydrologic mechanisms by estimating root water-uptake depths using an inverse model, based on observed productivity and atmosphere, at 30″ (∼1-km) global grids to capture the topography critical to soil hydrology. The resulting patterns of plant rooting depth bear a strong topographic and hydrologic signature at landscape to global scales. They underscore a fundamental plant-water feedback pathway that may be critical to understanding plant-mediated global change.

    View details for DOI 10.1073/pnas.1712381114

    View details for PubMedID 28923923

    View details for PubMedCentralID PMC5635924

  • Hydrologic resilience and Amazon productivity. Nature communications Ahlström, A., Canadell, J. G., Schurgers, G., Wu, M., Berry, J. A., Guan, K., Jackson, R. B. 2017; 8 (1): 387


    The Amazon rainforest is disproportionately important for global carbon storage and biodiversity. The system couples the atmosphere and land, with moist forest that depends on convection to sustain gross primary productivity and growth. Earth system models that estimate future climate and vegetation show little agreement in Amazon simulations. Here we show that biases in internally generated climate, primarily precipitation, explain most of the uncertainty in Earth system model results; models, empirical data and theory converge when precipitation biases are accounted for. Gross primary productivity, above-ground biomass and tree cover align on a hydrological relationship with a breakpoint at ~2000 mm annual precipitation, where the system transitions between water and radiation limitation of evapotranspiration. The breakpoint appears to be fairly stable in the future, suggesting resilience of the Amazon to climate change. Changes in precipitation and land use are therefore more likely to govern biomass and vegetation structure in Amazonia.Earth system model simulations of future climate in the Amazon show little agreement. Here, the authors show that biases in internally generated climate explain most of this uncertainty and that the balance between water-saturated and water-limited evapotranspiration controls the Amazon resilience to climate change.

    View details for DOI 10.1038/s41467-017-00306-z

    View details for PubMedID 28855518

    View details for PubMedCentralID PMC5577139

  • Key indicators to track current progress and future ambition of the Paris Agreement NATURE CLIMATE CHANGE Peters, G. P., Andrew, R. M., Canadell, J. G., Fuss, S., Jackson, R. B., Korsbakken, J. I., Le Quere, C., Nakicenovic, N. 2017; 7 (2): 118-?
  • Mineral estate conservation easements: a new policy instrument to address hydraulic fracturing and resource extraction Environmental Law Reporter Jackson, R. B., Owley, J., Salzman, J. 2017; 47: ELR 10112
  • A global meta-analysis of soil phosphorus dynamics after afforestation NEW PHYTOLOGIST Deng, Q., McMahon, D. E., Xiang, Y., Yu, C., Jackson, R. B., Hui, D. 2017; 213 (1): 181-192


    Afforestation significantly affects soil chemistry and biota, but its effects on the potentially growth-limiting nutrient phosphorus (P) had not to our knowledge been analyzed globally. We conducted a comprehensive meta-analysis of 220 independent sampling sites from 108 articles to evaluate global patterns and controls of soil P change following afforestation. Overall, total P concentration decreased by 11% and total P stock by 12% in the top 20 cm of mineral soil following afforestation, with no change in available P. Time since afforestation had no consistent effect on total P, while available P tended to increase with time. Prior land cover was the most influential factor for soil P change after afforestation, with available P increasing on native vegetation but decreasing on cropland. Afforestation increased available P by 22% without decreasing total P on formerly 'degraded' land, but depleted total P by 15% at nondegraded sites. Climate also influenced soil P response to afforestation, with larger P loss in the tropics. Afforestation did not appear to directly induce P limitation, as available P only decreased on cropland. However, substantial declines in total P may drive tropical plantations toward greater P limitation as the capacity to replenish available P decreases.

    View details for DOI 10.1111/nph.14119

    View details for Web of Science ID 000389184600020

    View details for PubMedID 27477387

  • Variability and quasi-decadal changes in the methane budget over the period 2000–2012 Atmosperic Chemistry and Physics Saunois, M., et al 2017; 17: 11135-11161
  • Towards real-time verification of carbon dioxide emissions Nature Climate Change Peters, G., Le Quéré, C., Andrew, R., Canadell, J., Friedlingstein, P., Ilyina, T., Jackson, R. B., Joos, F., Korsbakken, J. I., McKinley, G., Stich, S., Tans, P. 2017
  • Focus on Negative Emissions Environmental Research Letters Jackson, R. B., Canadell, J. G., Fuss, S., Milne, J., Nakicenovic, N., Tavoni, M. 2017; 12: 11020

    View details for DOI 10.1088/1748-9326/aa94ff

  • Warning signs for stabilizing global CO2 emissions Environmental Research Letters Jackson, R. B., Le Quéré, C., Andrew, R. M., Canadell, J. G., Peters, G. P., Roy, J., Wu, L. 2017; 12: 110202

    View details for DOI 10.1088/1748-9326/aa9662

  • The geochemistry of naturally occurring methane and saline groundwater in an area of unconventional shale gas development Geochimica et Cosmochimica Acta Harkness, J., Darrah, T. H., Warner, N. R., Whyte, C. J., Moore, M. T., Millot, R., Kloppmann, W., Jackson, R. B., Vengosh, A. 2017; 208: 302–334
  • The global methane budget 2000-2012 EARTH SYSTEM SCIENCE DATA Saunois, M., Bousquet, P., Poulter, B., Peregon, A., Ciais, P., Canadell, J. G., Dlugokencky, E. J., Etiope, G., Bastviken, D., Houweling, S., Janssens-Maenhout, G., Tubiello, F. N., Castaldi, S., Jackson, R. B., Alexe, M., Arora, V. K., Beerling, D. J., Bergamaschi, P., Blake, D. R., Brailsford, G., Brovkin, V., Bruhwiler, L., Crevoisier, C., Crill, P., Covey, K., Curry, C., Frankenberg, C., Gedney, N., Hoeglund-Isaksson, L., Ishizawa, M., Ito, A., Joos, F., Kim, H., Kleinen, T., Krummel, P., Lamarque, J., Langenfelds, R., Locatelli, R., Machida, T., Maksyutov, S., McDonald, K. C., Marshall, J., Melton, J. R., Morino, I., Naik, V., O'Doherty, S., Parmentier, F. W., Patra, P. K., Peng, C., Peng, S., Peters, G. P., Pison, I., Prigent, C., Prinn, R., Ramonet, M., Riley, W. J., Saito, M., Santini, M., Schroeder, R., Simpson, I. J., Spahni, R., Steele, P., Takizawa, A., Thornton, B. F., Tian, H., Tohjima, Y., Viovy, N., Voulgarakis, A., van Weele, M., van der Werf, G. R., Weiss, R., Wiedinmyer, C., Wilton, D. J., Wiltshire, A., Worthy, D., Wunch, D., Xu, X., Yoshida, Y., Zhang, B., Zhang, Z., Zhu, Q. 2016; 8 (2): 697-751
  • Stabilization of new carbon inputs rather than old carbon decomposition determines soil organic carbon shifts following woody or herbaceous vegetation transitions PLANT AND SOIL Eclesia, R. P., Jobbagy, E. G., Jackson, R. B., Rizzotto, M., Pineiro, G. 2016; 409 (1-2): 99-116
  • Identification and characterization of high methane-emitting abandoned oil and gas wells PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Kang, M., Christian, S., Celia, M. A., Mauzerall, D. L., Bill, M., Miller, A. R., Chen, Y., Conrad, M. E., Darrah, T. H., Jackson, R. B. 2016; 113 (48): 13636-13641


    Recent measurements of methane emissions from abandoned oil/gas wells show that these wells can be a substantial source of methane to the atmosphere, particularly from a small proportion of high-emitting wells. However, identifying high emitters remains a challenge. We couple 163 well measurements of methane flow rates; ethane, propane, and n-butane concentrations; isotopes of methane; and noble gas concentrations from 88 wells in Pennsylvania with synthesized data from historical documents, field investigations, and state databases. Using our databases, we (i) improve estimates of the number of abandoned wells in Pennsylvania; (ii) characterize key attributes that accompany high emitters, including depth, type, plugging status, and coal area designation; and (iii) estimate attribute-specific and overall methane emissions from abandoned wells. High emitters are best predicted as unplugged gas wells and plugged/vented gas wells in coal areas and appear to be unrelated to the presence of underground natural gas storage areas or unconventional oil/gas production. Repeat measurements over 2 years show that flow rates of high emitters are sustained through time. Our attribute-based methane emission data and our comprehensive estimate of 470,000-750,000 abandoned wells in Pennsylvania result in estimated state-wide emissions of 0.04-0.07 Mt (10(12) g) CH4 per year. This estimate represents 5-8% of annual anthropogenic methane emissions in Pennsylvania. Our methodology combining new field measurements with data mining of previously unavailable well attributes and numbers of wells can be used to improve methane emission estimates and prioritize cost-effective mitigation strategies for Pennsylvania and beyond.

    View details for DOI 10.1073/pnas.1605913113

    View details for Web of Science ID 000388835700048

    View details for PubMedID 27849603

    View details for PubMedCentralID PMC5137730

  • Research priorities for negative emissions ENVIRONMENTAL RESEARCH LETTERS Fuss, S., Jones, C. D., Kraxner, F., Peters, G. P., Smith, P., Tavoni, M., van Vuuren, D. P., Canadell, J. G., Jackson, R. B., Milne, J., Moreira, J. R., Nakicenovic, N., Sharifi, A., Yamagata, Y. 2016; 11 (11)
  • State of knowledge about energy development impacts on North American rangelands: An integrative approach JOURNAL OF ENVIRONMENTAL MANAGEMENT Kreuter, U. P., Iwaasa, A. D., Theodori, G. L., Ansley, R. J., Jackson, R. B., Fraser, L. H., Naeth, M. A., McGillivray, S., Garcia Moya, E. 2016; 180: 1-9


    To reduce dependence on foreign oil reserves, there has been a push in North America to develop alternative domestic energy resources. Relatively undeveloped renewable energy resources include biofuels and wind and solar energy, many of which occur predominantly on rangelands. Rangelands are also key areas for natural gas development from shales and tight sand formations. Accordingly, policies aimed at greater energy independence are likely to affect the delivery of crucial ecosystem services provided by rangelands. Assessing and dealing with the biophysical and socio-economic effects of energy development on rangeland ecosystems require an integrative and systematic approach that is predicated on a broad understanding of diverse issues related to energy development. In this article, we present a road map for developing an integrative assessment of energy development on rangelands in North America. We summarize current knowledge of socio-economic and biophysical aspects of rangeland based energy development, and we identify knowledge gaps and monitoring indicators to fill these knowledge gaps.

    View details for DOI 10.1016/j.jenvman.2016.05.007

    View details for Web of Science ID 000380418700001

    View details for PubMedID 27183477

  • Simulating the Earth system response to negative emissions ENVIRONMENTAL RESEARCH LETTERS Jones, C. D., Ciais, P., Davis, S. J., Friedlingstein, P., Gasser, T., Peters, G. P., Rogelj, J., van Vuuren, D. P., Canadell, J. G., Cowie, A., Jackson, R. B., Jonas, M., Kriegler, E., Littleton, E., Lowe, J. A., Milne, J., SHRESTHA, G., Smith, P., Torvanger, A., Wiltshire, A. 2016; 11 (9)
  • Trade-offs in water and carbon ecosystem services with land-use changes in grasslands ECOLOGICAL APPLICATIONS Kim, J. H., Jobbygy, E. G., Jackson, R. B. 2016; 26 (6): 1633-1644


    Increasing pressures for food, fiber, and fuel continue to drive global land-use changes. Efforts to optimize ecosystem services under alternative land uses are often hampered by the complex interactions and trade-offs among them. We examined the effects of land-use changes on ecosystem carbon storage and groundwater recharge in grasslands of Argentina and the United States to (1) understand the relationships between both services, (2) predict their responses to vegetation shifts across environmental gradients, and (3) explore how market or policy incentives for ecosystem services could affect land-use changes. A trade-off of ecosystem services was evident in most cases, with woody encroachment increasing carbon storage (+29 Mg C/ha) but decreasing groundwater recharge (-7.3 mm/yr) and conversions to rain-fed cultivation driving opposite changes (-32 Mg C/ha vs. +13 mm/yr). In contrast, crops irrigated with ground water tended to reduce both services compared to the natural grasslands they replaced. Combining economic values of the agricultural products together with the services, we highlight potentials for relatively modest financial incentives for ecosystem services to abate land-use changes and for incentives for carbon to drive land-use decisions over those of water. Our findings also identify key opportunities and caveats for some win-win and lose-lose land-use changes for more integrative and sustainable strategies for land management.

    View details for DOI 10.1890/15-0863.1

    View details for Web of Science ID 000383358000004

    View details for PubMedID 27755701

  • Canopy foliation and area as predictors of mortality risk from episodic drought for individual trees of Ashe juniper PLANT ECOLOGY Polley, H. W., Johnson, D. M., Jackson, R. B. 2016; 217 (9): 1105-1114
  • Quantifying drought-induced tree mortality in the open canopy woodlands of central Texas REMOTE SENSING OF ENVIRONMENT Schwantes, A. M., Swenson, J. J., Jackson, R. B. 2016; 181: 54-64
  • Salinity of deep groundwater in California: Water quantity, quality, and protection PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Kang, M., Jackson, R. B. 2016; 113 (28): 7768-7773


    Deep groundwater aquifers are poorly characterized but could yield important sources of water in California and elsewhere. Deep aquifers have been developed for oil and gas extraction, and this activity has created both valuable data and risks to groundwater quality. Assessing groundwater quantity and quality requires baseline data and a monitoring framework for evaluating impacts. We analyze 938 chemical, geological, and depth data points from 360 oil/gas fields across eight counties in California and depth data from 34,392 oil and gas wells. By expanding previous groundwater volume estimates from depths of 305 m to 3,000 m in California's Central Valley, an important agricultural region with growing groundwater demands, fresh [<3,000 ppm total dissolved solids (TDS)] groundwater volume is almost tripled to 2,700 km(3), most of it found shallower than 1,000 m. The 3,000-m depth zone also provides 3,900 km(3) of fresh and saline water, not previously estimated, that can be categorized as underground sources of drinking water (USDWs; <10,000 ppm TDS). Up to 19% and 35% of oil/gas activities have occurred directly in freshwater zones and USDWs, respectively, in the eight counties. Deeper activities, such as wastewater injection, may also pose a potential threat to groundwater, especially USDWs. Our findings indicate that California's Central Valley alone has close to three times the volume of fresh groundwater and four times the volume of USDWs than previous estimates suggest. Therefore, efforts to monitor and protect deeper, saline groundwater resources are needed in California and beyond.

    View details for DOI 10.1073/pnas.1600400113

    View details for Web of Science ID 000379694100038

    View details for PubMedID 27354527

    View details for PubMedCentralID PMC4948364

  • Forest biogeochemistry in response to drought GLOBAL CHANGE BIOLOGY Schlesinger, W. H., Dietze, M. C., Jackson, R. B., Phillips, R. P., Rhoades, C. C., Rustad, L. E., Vose, J. M. 2016; 22 (7): 2318-2328


    Trees alter their use and allocation of nutrients in response to drought, and changes in soil nutrient cycling and trace gas flux (N2 O and CH4 ) are observed when experimental drought is imposed on forests. In extreme droughts, trees are increasingly susceptible to attack by pests and pathogens, which can lead to major changes in nutrient flux to the soil. Extreme droughts often lead to more common and more intense forest fires, causing dramatic changes in the nutrient storage and loss from forest ecosystems. Changes in the future manifestation of drought will affect carbon uptake and storage in forests, leading to feedbacks to the Earth's climate system. We must improve the recognition of drought in nature, our ability to manage our forests in the face of drought, and the parameterization of drought in earth system models for improved predictions of carbon uptake and storage in the world's forests.

    View details for DOI 10.1111/gcb.13105

    View details for Web of Science ID 000378722000004

    View details for PubMedID 26403995

  • Aerial Surveys of Elevated Hydrocarbon Emissions from Oil and Gas Production Sites ENVIRONMENTAL SCIENCE & TECHNOLOGY Lyon, D. R., Alvarez, R. A., Zavala-Araiza, D., Brandt, A. R., Jackson, R. B., Hamburg, S. P. 2016; 50 (9): 4877-4886


    Oil and gas (O&G) well pads with high hydrocarbon emission rates may disproportionally contribute to total methane and volatile organic compound (VOC) emissions from the production sector. In turn, these emissions may be missing from most bottom-up emission inventories. We performed helicopter-based infrared camera surveys of more than 8000 O&G well pads in seven U.S. basins to assess the prevalence and distribution of high-emitting hydrocarbon sources (detection threshold ∼ 1-3 g s(-1)). The proportion of sites with such high-emitting sources was 4% nationally but ranged from 1% in the Powder River (Wyoming) to 14% in the Bakken (North Dakota). Emissions were observed three times more frequently at sites in the oil-producing Bakken and oil-producing regions of mixed basins (p < 0.0001, χ(2) test). However, statistical models using basin and well pad characteristics explained 14% or less of the variance in observed emission patterns, indicating that stochastic processes dominate the occurrence of high emissions at individual sites. Over 90% of almost 500 detected sources were from tank vents and hatches. Although tank emissions may be partially attributable to flash gas, observed frequencies in most basins exceed those expected if emissions were effectively captured and controlled, demonstrating that tank emission control systems commonly underperform. Tanks represent a key mitigation opportunity for reducing methane and VOC emissions.

    View details for DOI 10.1021/acs.est.6b00705

    View details for PubMedID 27045743

  • Impact to Underground Sources of Drinking Water and Domestic Wells from Production Well Stimulation and Completion Practices in the Pavillion, Wyoming, Field ENVIRONMENTAL SCIENCE & TECHNOLOGY DiGiulio, D. C., Jackson, R. B. 2016; 50 (8): 4524-4536


    A comprehensive analysis of all publicly available data and reports was conducted to evaluate impact to Underground Sources of Drinking Water (USDWs) as a result of acid stimulation and hydraulic fracturing in the Pavillion, WY, Field. Although injection of stimulation fluids into USDWs in the Pavillion Field was documented by EPA, potential impact to USDWs at the depths of stimulation as a result of this activity was not previously evaluated. Concentrations of major ions in produced water samples outside expected levels in the Wind River Formation, leakoff of stimulation fluids into formation media, and likely loss of zonal isolation during stimulation at several production wells, indicates that impact to USDWs has occurred. Detection of organic compounds used for well stimulation in samples from two monitoring wells installed by EPA, plus anomalies in major ion concentrations in water from one of these monitoring wells, provide additional evidence of impact to USDWs and indicate upward solute migration to depths of current groundwater use. Detections of diesel range organics and other organic compounds in domestic wells <600 m from unlined pits used prior to the mid-1990s to dispose diesel-fuel based drilling mud and production fluids suggest impact to domestic wells as a result of legacy pit disposal practices.

    View details for DOI 10.1021/acs.est.5b04970

    View details for PubMedID 27022977

  • The growing role of methane in anthropogenic climate change Environmental Research Letters Saunois, M., Jackson, R. B., Bousquet, P., Poulter, B., Canadell, J. G. 2016; 11
  • Response to Comment on "Impact to Underground Sources of Drinking Water and Domestic Wells from Production Well Stimulation and Completion Practices in the Pavillion, Wyoming Field". Environmental science & technology DiGiulio, D. C., Jackson, R. B. 2016; 50 (19): 10771–72

    View details for PubMedID 27696860

  • Identification and characterization of high methane-emitting abandoned oil and gas wells Proceedings of the National Academy of Sciences of the United States of America Kang, M., Christian, S., Celia, M. A., Mauzerall, D. L., Bill, M., Miller, A. R., Chen, Y., Conrad, M. E., Darrah, T. H., Jackson, R. B. 2016; 113: 13636–13641

    View details for DOI 10.1073/pnas.1605913113

  • Toward more realistic projections of soil carbon dynamics by Earth system models GLOBAL BIOGEOCHEMICAL CYCLES Luo, Y., Ahlstrom, A., Allison, S. D., Batjes, N. H., Brovkin, V., Carvalhais, N., Chappell, A., Ciais, P., Davidson, E. A., Finzi, A., Georgiou, K., Guenet, B., Hararuk, O., Harden, J. W., He, Y., Hopkins, F., Jiang, L., Koven, C., Jackson, R. B., Jones, C. D., Lara, M. J., Liang, J., McGuire, A. D., Parton, W., Peng, C., Randerson, J. T., Salazar, A., Sierra, C. A., Smith, M. J., Tian, H., Todd-Brown, K. E., Torn, M., van Groenigen, K. J., Wang, Y. P., West, T. O., Wei, Y., Wieder, W. R., Xia, J., Xu, X., Xu, X., Zhou, T. 2016; 30 (1): 40-56
  • Water Use and Management in the Bakken Shale Oil Play in North Dakota Environmental Sciene and Technology Horner, R. M., Harto, C. B., Jackson, R. B., Lowry, E. R., Brandt, A. R., Yeskoo, T. W., Murphy, D. J., Clark, C. E. 2016; 50: 3275-3282

    View details for DOI 10.1021/acs.est.5b04079

  • Biophysical and economic limits to negative CO2 emissions NATURE CLIMATE CHANGE Smith, P., Davis, S. J., Creutzig, F., Fuss, S., Minx, J., Gabrielle, B., Kato, E., Jackson, R. B., Cowie, A., Kriegler, E., Van Vuuren, D. P., Rogelj, J., Ciais, P., Milne, J., Canadell, J. G., McCollum, D., Peters, G., Andrew, R., Krey, V., Shrestha, G., Friedlingstein, P., Gasser, T., Gruebler, A., Heidug, W. K., Jonas, M., Jones, C. D., Kraxner, F., Littleton, E., Lowe, J., Moreira, J. R., Nakicenovic, N., Obersteiner, M., Patwardhan, A., Rogner, M., Rubin, E., Sharifi, A., Torvanger, A., Yamagata, Y., Edmonds, J., Cho, Y. 2016; 6: 42-50
  • Reaching Peak Emissions NATURE CLIMATE CHANGE Jackson, R. B., Canadell, J. G., Le Quéré, C., Andrew, R. M., Korsbakken, J. I., Peters, G. P., Nakicenovic , N. 2016; 6: 7-10

    View details for DOI 10.1038/nclimate2892

  • The evolution of Devonian hydrocarbon gases in shallow aquifers of the northern Appalachian Basin: Insights from integrating noble gas and hydrocarbon geochemistry GEOCHIMICA ET COSMOCHIMICA ACTA Darrah, T. H., Jackson, R. B., Vengosh, A., Warner, N. R., Whyte, C. J., Walsh, T. B., Kondash, A. J., Poreda, R. J. 2015; 170: 321-355
  • Elevated levels of diesel range organic compounds in groundwater near Marcellus gas operations are derived from surface activities. Proceedings of the National Academy of Sciences of the United States of America Drollette, B. D., Hoelzer, K., Warner, N. R., Darrah, T. H., Karatum, O., O'Connor, M. P., Nelson, R. K., Fernandez, L. A., Reddy, C. M., Vengosh, A., Jackson, R. B., Elsner, M., Plata, D. L. 2015; 112 (43): 13184-13189

    View details for DOI 10.1073/pnas.1511474112

    View details for PubMedID 26460018

  • Natural Gas Pipeline Replacement Programs Reduce Methane Leaks and Improve Consumer Safety ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS Gallagher, M. E., Down, A., Ackley, R. C., Zhao, K., Phillips, N., Jackson, R. B. 2015; 2 (10): 286-291
  • Quantifying surface albedo and other direct biogeophysical climate forcings of forestry activities GLOBAL CHANGE BIOLOGY Bright, R. M., Zhao, K., Jackson, R. B., Cherubini, F. 2015; 21 (9): 3246-3266


    By altering fluxes of heat, momentum, and moisture exchanges between the land surface and atmosphere, forestry and other land-use activities affect climate. Although long recognized scientifically as being important, these so-called biogeophysical forcings are rarely included in climate policies for forestry and other land management projects due to the many challenges associated with their quantification. Here, we review the scientific literature in the fields of atmospheric science and terrestrial ecology in light of three main objectives: (i) to elucidate the challenges associated with quantifying biogeophysical climate forcings connected to land use and land management, with a focus on the forestry sector; (ii) to identify and describe scientific approaches and/or metrics facilitating the quantification and interpretation of direct biogeophysical climate forcings; and (iii) to identify and recommend research priorities that can help overcome the challenges of their attribution to specific land-use activities, bridging the knowledge gap between the climate modeling, forest ecology, and resource management communities. We find that ignoring surface biogeophysics may mislead climate mitigation policies, yet existing metrics are unlikely to be sufficient. Successful metrics ought to (i) include both radiative and nonradiative climate forcings; (ii) reconcile disparities between biogeophysical and biogeochemical forcings, and (iii) acknowledge trade-offs between global and local climate benefits. We call for more coordinated research among terrestrial ecologists, resource managers, and coupled climate modelers to harmonize datasets, refine analytical techniques, and corroborate and validate metrics that are more amenable to analyses at the scale of an individual site or region.

    View details for DOI 10.1111/gcb.12951

    View details for Web of Science ID 000360998400007

    View details for PubMedID 25914206

  • Pre-drilling background groundwater quality in the Deep River Triassic Basin of central North Carolina, USA APPLIED GEOCHEMISTRY Down, A., Schreglmann, K., Plata, D. L., Elsner, M., Warner, N. R., Vengosh, A., Moore, K., Coleman, D., Jackson, R. B. 2015; 60: 3-13
  • The Depths of Hydraulic Fracturing and Accompanying Water Use Across the United States ENVIRONMENTAL SCIENCE & TECHNOLOGY Jackson, R. B., Lowry, E. R., Pickle, A., Kang, M., DiGiulio, D., Zhao, K. 2015; 49 (15): 8969-8976


    Reports highlight the safety of hydraulic fracturing for drinking water if it occurs "many hundreds of meters to kilometers underground". To our knowledge, however, no comprehensive analysis of hydraulic fracturing depths exists. Based on fracturing depths and water use for ∼44 000 wells reported between 2010 and 2013, the average fracturing depth across the United States was 8300 ft (∼2500 m). Many wells (6900; 16%) were fractured less than a mile from the surface, and 2600 wells (6%) were fractured above 3000 ft (900 m), particularly in Texas (850 wells), California (720), Arkansas (310), and Wyoming (300). Average water use per well nationally was 2 400 000 gallons (9 200 000 L), led by Arkansas (5 200 000 gallons), Louisiana (5 100 000 gallons), West Virginia (5 000 000 gallons), and Pennsylvania (4 500 000 gallons). Two thousand wells (∼5%) shallower than one mile and 350 wells (∼1%) shallower than 3000 ft were hydraulically fractured with >1 million gallons of water, particularly in Arkansas, New Mexico, Texas, Pennsylvania, and California. Because hydraulic fractures can propagate 2000 ft upward, shallow wells may warrant special safeguards, including a mandatory registry of locations, full chemical disclosure, and, where horizontal drilling is used, predrilling water testing to a radius 1000 ft beyond the greatest lateral extent.

    View details for DOI 10.1021/acs.est.5b01228

    View details for PubMedID 26196164

  • Redefining fine roots improves understanding of below-ground contributions to terrestrial biosphere processes NEW PHYTOLOGIST McCormack, M. L., Dickie, I. A., Eissenstat, D. M., Fahey, T. J., Fernandez, C. W., Guo, D., Helmisaari, H., Hobbie, E. A., Iversen, C. M., Jackson, R. B., Leppalammi-Kujansuu, J., Norby, R. J., Phillips, R. P., Pregitzer, K. S., Pritchard, S. G., Rewald, B., Zadworny, M. 2015; 207 (3): 505-518


    505 I. 506 II. 506 III. 508 IV. 512 V. 513 VI. 514 515 References 515 SUMMARY: Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain because of the challenges of consistently measuring and interpreting fine-root systems. Traditionally, fine roots have been defined as all roots ≤ 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. Here, we demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, fine roots are either separated into individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine-root pool. Using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally - a c. 30% reduction from previous estimates assuming a single fine-root pool. Future work developing tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi into fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand below-ground processes in the terrestrial biosphere.

    View details for DOI 10.1111/nph.13363

    View details for Web of Science ID 000357824400006

    View details for PubMedID 25756288

  • Plant community change mediates the response of foliar d(15)N to CO 2 enrichment in mesic grasslands. Oecologia Polley, H. W., Derner, J. D., Jackson, R. B., Gill, R. A., Procter, A. C., Fay, P. A. 2015; 178 (2): 591-601


    Rising atmospheric CO2 concentration may change the isotopic signature of plant N by altering plant and microbial processes involved in the N cycle. CO2 may increase leaf δ(15)N by increasing plant community productivity, C input to soil, and, ultimately, microbial mineralization of old, (15)N-enriched organic matter. We predicted that CO2 would increase aboveground productivity (ANPP; g biomass m(-2)) and foliar δ(15)N values of two grassland communities in Texas, USA: (1) a pasture dominated by a C4 exotic grass, and (2) assemblages of tallgrass prairie species, the latter grown on clay, sandy loam, and silty clay soils. Grasslands were exposed in separate experiments to a pre-industrial to elevated CO2 gradient for 4 years. CO2 stimulated ANPP of pasture and of prairie assemblages on each of the three soils, but increased leaf δ(15)N only for prairie plants on a silty clay. δ(15)N increased linearly as mineral-associated soil C declined on the silty clay. Mineral-associated C declined as ANPP increased. Structural equation modeling indicted that CO2 increased ANPP partly by favoring a tallgrass (Sorghastrum nutans) over a mid-grass species (Bouteloua curtipendula). CO2 may have increased foliar δ(15)N on the silty clay by reducing fractionation during N uptake and assimilation. However, we interpret the soil-specific, δ(15)N-CO2 response as resulting from increased ANPP that stimulated mineralization from recalcitrant organic matter. By contrast, CO2 favored a forb species (Solanum dimidiatum) with higher δ(15)N than the dominant grass (Bothriochloa ischaemum) in pasture. CO2 enrichment changed grassland δ(15)N by shifting species relative abundances.

    View details for DOI 10.1007/s00442-015-3221-x

    View details for PubMedID 25604918

  • Greater humification of belowground than aboveground biomass carbon into particulate soil organic matter in no-till corn and soybean crops SOIL BIOLOGY & BIOCHEMISTRY Mazzilli, S. R., Kemanian, A. R., Ernst, O. R., Jackson, R. B., Pineiro, G. 2015; 85: 22-30
  • Woody Plant-Cover Dynamics in Argentine Savannas from the 1880s to 2000s: The Interplay of Encroachment and Agriculture Conversion at Varying Scales ECOSYSTEMS Gonzalez-Roglich, M., Swenson, J. J., Villarreal, D., Jobbagy, E. G., Jackson, R. B. 2015; 18 (3): 481-492
  • Soil carbon responses to past and future CO2 in three Texas prairie soils SOIL BIOLOGY & BIOCHEMISTRY Procter, A. C., Gill, R. A., Fay, P. A., Polley, H. W., Jackson, R. B. 2015; 83: 66-75
  • Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA McKain, K. K., Down, A., Raciti, S. M., Budney, J., Hutyra, L. R., Floerchinger, C., Herndon, S. C., Nehrkorn, T., Zahniser, M. S., Jackson, R. B., Phillips, N., Wofsy, S. C. 2015; 112 (7): 1941-1946


    Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4 ⋅ m(-2) ⋅ y(-1). Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ∼ 60-100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory.

    View details for DOI 10.1073/pnas.1416261112

    View details for Web of Science ID 000349446000040

    View details for PubMedID 25617375

    View details for PubMedCentralID PMC4343086

  • Noble Gases: A New Technique for Fugitive Gas Investigation in Groundwater GROUNDWATER Darrah, T. H., Jackson, R. B., Vengosh, A., Warner, N. R., Poreda, R. J. 2015; 53 (1): 23-28

    View details for Web of Science ID 000347981800008

    View details for PubMedID 25713829

  • Two or three degrees: CO2 emissions and global temperature impacts THE BRIDGE Jackson, R. B., Friedlingstein, P., Canadell, J. G., Andrew, R. M. 2015; 45 (2): 16-21
  • Vulnerabilities and opportunities at the nexus of electricity, water and climate ENVIRONMENTAL RESEARCH LETTERS Frumhoff, P. C., Burkett, V., Jackson, R. B., Newmark, R., Overpeck, J., Webber, M. 2015; 10: 080201
  • Fungal Community Responses to Past and Future Atmospheric CO2 Differ by Soil Type. Applied and environmental microbiology Procter, A. C., Ellis, J. C., Fay, P. A., Polley, H. W., Jackson, R. B. 2014; 80 (23): 7364-77


    Soils sequester and release substantial atmospheric carbon, but the contribution of fungal communities to soil carbon balance under rising CO2 is not well understood. Soil properties likely mediate these fungal responses but are rarely explored in CO2 experiments. We studied soil fungal communities in a grassland ecosystem exposed to a preindustrial-to-future CO2 gradient (250 to 500 ppm) in a black clay soil and a sandy loam soil. Sanger sequencing and pyrosequencing of the rRNA gene cluster revealed that fungal community composition and its response to CO2 differed significantly between soils. Fungal species richness and relative abundance of Chytridiomycota (chytrids) increased linearly with CO2 in the black clay (P < 0.04, R(2) > 0.7), whereas the relative abundance of Glomeromycota (arbuscular mycorrhizal fungi) increased linearly with elevated CO2 in the sandy loam (P = 0.02, R(2) = 0.63). Across both soils, decomposition rate was positively correlated with chytrid relative abundance (r = 0.57) and, in the black clay soil, fungal species richness. Decomposition rate was more strongly correlated with microbial biomass (r = 0.88) than with fungal variables. Increased labile carbon availability with elevated CO2 may explain the greater fungal species richness and Chytridiomycota abundance in the black clay soil, whereas increased phosphorus limitation may explain the increase in Glomeromycota at elevated CO2 in the sandy loam. Our results demonstrate that soil type plays a key role in soil fungal responses to rising atmospheric CO2.

    View details for DOI 10.1128/AEM.02083-14

    View details for PubMedID 25239904

    View details for PubMedCentralID PMC4249185

  • New Tracers Identify Hydraulic Fracturing Fluids and Accidental Releases from Oil and Gas Operations ENVIRONMENTAL SCIENCE & TECHNOLOGY Warner, N. R., Darrah, T. H., Jackson, R. B., Millot, R., Kloppmann, W., Vengosh, A. 2014; 48 (21): 12552-12560

    View details for DOI 10.1021/es5032135

    View details for Web of Science ID 000344449100010

  • Shifting carbon pools along a plant cover gradient in woody encroached savannas of central Argentina FOREST ECOLOGY AND MANAGEMENT Gonzalez-Roglich, M., Swenson, J. J., Jobbagy, E. G., Jackson, R. B. 2014; 331: 71-78
  • Role of aquaporin activity in regulating deep and shallow root hydraulic conductance during extreme drought TREES-STRUCTURE AND FUNCTION Johnson, D. M., Sherrard, M. E., Domec, J., Jackson, R. B. 2014; 28 (5): 1323-1331
  • Noble gases identify the mechanisms of fugitive gas contamination in drinking-water wells overlying the Marcellus and Barnett Shales. Proceedings of the National Academy of Sciences of the United States of America Darrah, T. H., Vengosh, A., Jackson, R. B., Warner, N. R., Poreda, R. J. 2014; 111 (39): 14076-81


    Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Barnett Shales, respectively, examining hydrocarbon abundance and isotopic compositions (e.g., C2H6/CH4, δ(13)C-CH4) and providing, to our knowledge, the first comprehensive analyses of noble gases and their isotopes (e.g., (4)He, (20)Ne, (36)Ar) in groundwater near shale-gas wells. We addressed two questions. (i) Are elevated levels of hydrocarbon gases in drinking-water aquifers near gas wells natural or anthropogenic? (ii) If fugitive gas contamination exists, what mechanisms cause it? Against a backdrop of naturally occurring salt- and gas-rich groundwater, we identified eight discrete clusters of fugitive gas contamination, seven in Pennsylvania and one in Texas that showed increased contamination through time. Where fugitive gas contamination occurred, the relative proportions of thermogenic hydrocarbon gas (e.g., CH4, (4)He) were significantly higher (P < 0.01) and the proportions of atmospheric gases (air-saturated water; e.g., N2, (36)Ar) were significantly lower (P < 0.01) relative to background groundwater. Noble gas isotope and hydrocarbon data link four contamination clusters to gas leakage from intermediate-depth strata through failures of annulus cement, three to target production gases that seem to implicate faulty production casings, and one to an underground gas well failure. Noble gas data appear to rule out gas contamination by upward migration from depth through overlying geological strata triggered by horizontal drilling or hydraulic fracturing.

    View details for DOI 10.1073/pnas.1322107111

    View details for PubMedID 25225410

    View details for PubMedCentralID PMC4191804

  • Oil and gas wells and their integrity: Implications for shale and unconventional resource exploitation MARINE AND PETROLEUM GEOLOGY Davies, R. J., Almond, S., Ward, R. S., Jackson, R. B., Adams, C., Worrall, F., Herringshaw, L. G., Gluyas, J. G., Whitehead, M. A. 2014; 56: 239-254
  • Air impacts of increased natural gas acquisition, processing, and use: a critical review. Environmental science & technology Moore, C. W., Zielinska, B., Pétron, G., Jackson, R. B. 2014; 48 (15): 8349-8359


    During the past decade, technological advancements in the United States and Canada have led to rapid and intensive development of many unconventional natural gas plays (e.g., shale gas, tight sand gas, coal-bed methane), raising concerns about environmental impacts. Here, we summarize the current understanding of local and regional air quality impacts of natural gas extraction, production, and use. Air emissions from the natural gas life cycle include greenhouse gases, ozone precursors (volatile organic compounds and nitrogen oxides), air toxics, and particulates. National and state regulators primarily use generic emission inventories to assess the climate, air quality, and health impacts of natural gas systems. These inventories rely on limited, incomplete, and sometimes outdated emission factors and activity data, based on few measurements. We discuss case studies for specific air impacts grouped by natural gas life cycle segment, summarize the potential benefits of using natural gas over other fossil fuels, and examine national and state emission regulations pertaining to natural gas systems. Finally, we highlight specific gaps in scientific knowledge and suggest that substantial additional measurements of air emissions from the natural gas life cycle are essential to understanding the impacts and benefits of this resource.

    View details for DOI 10.1021/es4053472

    View details for PubMedID 24588259

  • Risks and risk governance in unconventional shale gas development. Environmental science & technology Small, M. J., Stern, P. C., Bomberg, E., Christopherson, S. M., Goldstein, B. D., Israel, A. L., Jackson, R. B., Krupnick, A., Mauter, M. S., Nash, J., North, D. W., Olmstead, S. M., Prakash, A., Rabe, B., Richardson, N., Tierney, S., Webler, T., Wong-Parodi, G., Zielinska, B. 2014; 48 (15): 8289-8297


    A broad assessment is provided of the current state of knowledge regarding the risks associated with shale gas development and their governance. For the principal domains of risk, we identify observed and potential hazards and promising mitigation options to address them, characterizing current knowledge and research needs. Important unresolved research questions are identified for each area of risk; however, certain domains exhibit especially acute deficits of knowledge and attention, including integrated studies of public health, ecosystems, air quality, socioeconomic impacts on communities, and climate change. For these, current research and analysis are insufficient to either confirm or preclude important impacts. The rapidly evolving landscape of shale gas governance in the U.S. is also assessed, noting challenges and opportunities associated with the current decentralized (state-focused) system of regulation. We briefly review emerging approaches to shale gas governance in other nations, and consider new governance initiatives and options in the U.S. involving voluntary industry certification, comprehensive development plans, financial instruments, and possible future federal roles. In order to encompass the multiple relevant disciplines, address the complexities of the evolving shale gas system and reduce the many key uncertainties needed for improved management, a coordinated multiagency federal research effort will need to be implemented.

    View details for DOI 10.1021/es502111u

    View details for PubMedID 24983403

  • A critical review of the risks to water resources from unconventional shale gas development and hydraulic fracturing in the United States. Environmental science & technology Vengosh, A., Jackson, R. B., Warner, N., Darrah, T. H., Kondash, A. 2014; 48 (15): 8334-8348


    The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations pose to water resources, with an emphasis on case studies mostly from the U.S. Four potential risks for water resources are identified: (1) the contamination of shallow aquifers with fugitive hydrocarbon gases (i.e., stray gas contamination), which can also potentially lead to the salinization of shallow groundwater through leaking natural gas wells and subsurface flow; (2) the contamination of surface water and shallow groundwater from spills, leaks, and/or the disposal of inadequately treated shale gas wastewater; (3) the accumulation of toxic and radioactive elements in soil or stream sediments near disposal or spill sites; and (4) the overextraction of water resources for high-volume hydraulic fracturing that could induce water shortages or conflicts with other water users, particularly in water-scarce areas. Analysis of published data (through January 2014) reveals evidence for stray gas contamination, surface water impacts in areas of intensive shale gas development, and the accumulation of radium isotopes in some disposal and spill sites. The direct contamination of shallow groundwater from hydraulic fracturing fluids and deep formation waters by hydraulic fracturing itself, however, remains controversial.

    View details for DOI 10.1021/es405118y

    View details for PubMedID 24606408

  • Priming of soil organic carbon decomposition induced by corn compared to soybean crops SOIL BIOLOGY & BIOCHEMISTRY Mazzilli, S. R., Kemanian, A. R., Ernst, O. R., Jackson, R. B., Pineiro, G. 2014; 75: 273-281
  • The integrity of oil and gas wells. Proceedings of the National Academy of Sciences of the United States of America Jackson, R. B. 2014; 111 (30): 10902-10903

    View details for DOI 10.1073/pnas.1410786111

    View details for PubMedID 25009178

    View details for PubMedCentralID PMC4121783

  • Impacts of climate change drivers on C-4 grassland productivity: scaling driver effects through the plant community JOURNAL OF EXPERIMENTAL BOTANY Polley, H. W., Derner, J. D., Jackson, R. B., Wilsey, B. J., Fay, P. A. 2014; 65 (13): 3415-3424


    Climate change drivers affect plant community productivity via three pathways: (i) direct effects of drivers on plants; (ii) the response of species abundances to drivers (community response); and (iii) the feedback effect of community change on productivity (community effect). The contribution of each pathway to driver-productivity relationships depends on functional traits of dominant species. We used data from three experiments in Texas, USA, to assess the role of community dynamics in the aboveground net primary productivity (ANPP) response of C4 grasslands to two climate drivers applied singly: atmospheric CO2 enrichment and augmented summer precipitation. The ANPP-driver response differed among experiments because community responses and effects differed. ANPP increased by 80-120g m(-2) per 100 μl l(-1) rise in CO2 in separate experiments with pasture and tallgrass prairie assemblages. Augmenting ambient precipitation by 128mm during one summer month each year increased ANPP more in native than in exotic communities in a third experiment. The community effect accounted for 21-38% of the ANPP CO2 response in the prairie experiment but little of the response in the pasture experiment. The community response to CO2 was linked to species traits associated with greater soil water from reduced transpiration (e.g. greater height). Community effects on the ANPP CO2 response and the greater ANPP response of native than exotic communities to augmented precipitation depended on species differences in transpiration efficiency. These results indicate that feedbacks from community change influenced ANPP-driver responses. However, the species traits that regulated community effects on ANPP differed from the traits that determined how communities responded to drivers.

    View details for DOI 10.1093/jxb/eru009

    View details for Web of Science ID 000339953400009

    View details for PubMedID 24501178

  • Nitrogen Fertilization Has a Stronger Effect on Soil Nitrogen-Fixing Bacterial Communities than Elevated Atmospheric CO2 APPLIED AND ENVIRONMENTAL MICROBIOLOGY Berthrong, S. T., Yeager, C. M., Gallegos-Graves, L., Steven, B., Eichorst, S. A., Jackson, R. B., Kuske, C. R. 2014; 80 (10): 3103-3112


    Biological nitrogen fixation is the primary supply of N to most ecosystems, yet there is considerable uncertainty about how N-fixing bacteria will respond to global change factors such as increasing atmospheric CO2 and N deposition. Using the nifH gene as a molecular marker, we studied how the community structure of N-fixing soil bacteria from temperate pine, aspen, and sweet gum stands and a brackish tidal marsh responded to multiyear elevated CO2 conditions. We also examined how N availability, specifically, N fertilization, interacted with elevated CO2 to affect these communities in the temperate pine forest. Based on data from Sanger sequencing and quantitative PCR, the soil nifH composition in the three forest systems was dominated by species in the Geobacteraceae and, to a lesser extent, Alphaproteobacteria. The N-fixing-bacterial-community structure was subtly altered after 10 or more years of elevated atmospheric CO2, and the observed shifts differed in each biome. In the pine forest, N fertilization had a stronger effect on nifH community structure than elevated CO2 and suppressed the diversity and abundance of N-fixing bacteria under elevated atmospheric CO2 conditions. These results indicate that N-fixing bacteria have complex, interacting responses that will be important for understanding ecosystem productivity in a changing climate.

    View details for DOI 10.1128/AEM.04034-13

    View details for Web of Science ID 000335386200017

    View details for PubMedID 24610855

    View details for PubMedCentralID PMC4018900

  • Biophysical forcings of land-use changes from potential forestry activities in North America ECOLOGICAL MONOGRAPHS Zhao, K., Jackson, R. B. 2014; 84 (2): 329-353

    View details for DOI 10.1890/12-1705.1

    View details for Web of Science ID 000335859700007

  • Geophysical subsurface imaging for ecological applications NEW PHYTOLOGIST Jayawickreme, D. H., Jobbagy, E. G., Jackson, R. B. 2014; 201 (4): 1170-1175


    Ecologists, ecohydrologists, and biogeochemists need detailed insights into belowground properties and processes, including changes in water, salts, and other elements that can influence ecosystem productivity and functioning. Relying on traditional sampling and observation techniques for such insights can be costly, time consuming, and infeasible, especially if the spatial scales involved are large. Geophysical imaging provides an alternative or complement to traditional methods to gather subsurface variables across time and space. In this paper, we review aspects of geophysical imaging, particularly electrical and electromagnetic imaging, that may benefit ecologists seeking clearer understanding of the shallow subsurface. Using electrical resistivity imaging, for example, we have been able to successfully show the effect of land-use conversions to agriculture on salt mobilization and leaching across kilometer-long transects and to depths of tens of meters. Recent advances in ground-penetrating radar and other geophysical imaging methods currently provide opportunities for subsurface imaging with sufficient detail to locate small (≥5 cm diameter) animal burrows and plant roots, observe soil-water and vegetation spatial correlations in small watersheds, estuaries, and marshes, and quantify changes in groundwater storage at local to regional scales using geophysical data from ground- and space-based platforms. Ecologists should benefit from adopting these minimally invasive, scalable imaging technologies to explore the subsurface and advance our collective research.

    View details for DOI 10.1111/nph.12619

    View details for Web of Science ID 000338510200013

    View details for PubMedID 24649489

  • Contrasting hydraulic architecture and function in deep and shallow roots of tree species from a semi-arid habitat ANNALS OF BOTANY Johnson, D. M., Brodersen, C. R., Reed, M., Domec, J., Jackson, R. B. 2014; 113 (4): 617-627


    Despite the importance of vessels in angiosperm roots for plant water transport, there is little research on the microanatomy of woody plant roots. Vessels in roots can be interconnected networks or nearly solitary, with few vessel-vessel connections. Species with few connections are common in arid habitats, presumably to isolate embolisms. In this study, measurements were made of root vessel pit sizes, vessel air-seeding pressures, pit membrane thicknesses and the degree of vessel interconnectedness in deep (approx. 20 m) and shallow (<10 cm) roots of two co-occurring species, Sideroxylon lanuginosum and Quercus fusiformis.Scanning electron microscopy was used to image pit dimensions and to measure the distance between connected vessels. The number of connected vessels in larger samples was determined by using high-resolution computed tomography and three-dimensional (3-D) image analysis. Individual vessel air-seeding pressures were measured using a microcapillary method. The thickness of pit membranes was measured using transmission electron microscopy.Vessel pit size varied across both species and rooting depths. Deep Q. fusiformis roots had the largest pits overall (>500 µm) and more large pits than either shallow Q. fusiformis roots or S. lanuginosum roots. Vessel air-seeding pressures were approximately four times greater in Q. fusiformis than in S. lanuginosum and 1·3-1·9 times greater in shallow roots than in deep roots. Sideroxylon lanuginosum had 34-44 % of its vessels interconnected, whereas Q. fusiformis only had 1-6 % of its vessels connected. Vessel air-seeding pressures were unrelated to pit membrane thickness but showed a positive relationship with vessel interconnectedness.These data support the hypothesis that species with more vessel-vessel integration are often less resistant to embolism than species with isolated vessels. This study also highlights the usefulness of tomography for vessel network analysis and the important role of 3-D xylem organization in plant hydraulic function.

    View details for DOI 10.1093/aob/mct294

    View details for Web of Science ID 000332251700005

    View details for PubMedID 24363350

    View details for PubMedCentralID PMC3936587

  • China's fuel gas sector: History, current status, and future prospects UTILITIES POLICY Yang, C., Zhou, Y., Jackson, R. B. 2014; 28: 12-21
  • Natural Gas Pipeline Leaks Across Washington, DC ENVIRONMENTAL SCIENCE & TECHNOLOGY Jackson, R. B., Down, A., Phillips, N. G., Ackley, R. C., Cook, C. W., Plata, D. L., Zhao, K. 2014; 48 (3): 2051-2058


    Pipeline safety in the United States has increased in recent decades, but incidents involving natural gas pipelines still cause an average of 17 fatalities and $133 M in property damage annually. Natural gas leaks are also the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. To reduce pipeline leakage and increase consumer safety, we deployed a Picarro G2301 Cavity Ring-Down Spectrometer in a car, mapping 5893 natural gas leaks (2.5 to 88.6 ppm CH4) across 1500 road miles of Washington, DC. The δ(13)C-isotopic signatures of the methane (-38.2‰ ± 3.9‰ s.d.) and ethane (-36.5 ± 1.1 s.d.) and the CH4:C2H6 ratios (25.5 ± 8.9 s.d.) closely matched the pipeline gas (-39.0‰ and -36.2‰ for methane and ethane; 19.0 for CH4/C2H6). Emissions from four street leaks ranged from 9200 to 38,200 L CH4 day(-1) each, comparable to natural gas used by 1.7 to 7.0 homes, respectively. At 19 tested locations, 12 potentially explosive (Grade 1) methane concentrations of 50,000 to 500,000 ppm were detected in manholes. Financial incentives and targeted programs among companies, public utility commissions, and scientists to reduce leaks and replace old cast-iron pipes will improve consumer safety and air quality, save money, and lower greenhouse gas emissions.

    View details for DOI 10.1021/es404474x

    View details for Web of Science ID 000331015100083

    View details for PubMedID 24432903

  • Betting on Negative Emissions NATURE CLIMATE CHANGE Fuss, S., Canadell, J. G., Peters, G. P., Tavoni, M., Andrew, R. M., Ciais, P., Jackson, R. B., Jones, C. D., Kraxner, F., Nakicenovic, N., Le Quere, C., Raupach, M. R., Sharifi, A., Smith, P., Yamagata, Y. 2014; 4: 850-853

    View details for DOI 10.1038/nclimate2392

  • The Environmental Costs and Benefits of Fracking ANNUAL REVIEW OF ENVIRONMENT AND RESOURCES, VOL 39 Jackson, R. B., Vengosh, A., Carey, J. W., Davies, R. J., Darrah, T. H., O'Sullivan, F., Petron, G. 2014; 39: 327-362
  • Land-use and topography shape soil and groundwater salinity in central Argentina AGRICULTURAL WATER MANAGEMENT Nosetto, M. D., ACOSTA, A. M., Jayawickreme, D. H., Ballesteros, S. I., Jackson, R. B., Jobbagy, E. G. 2013; 129: 120-129
  • Impacts of Shale Gas Wastewater Disposal on Water Quality in Western Pennsylvania ENVIRONMENTAL SCIENCE & TECHNOLOGY Warner, N. R., Christie, C. A., Jackson, R. B., Vengosh, A. 2013; 47 (20): 11849-11857


    The safe disposal of liquid wastes associated with oil and gas production in the United States is a major challenge given their large volumes and typically high levels of contaminants. In Pennsylvania, oil and gas wastewater is sometimes treated at brine treatment facilities and discharged to local streams. This study examined the water quality and isotopic compositions of discharged effluents, surface waters, and stream sediments associated with a treatment facility site in western Pennsylvania. The elevated levels of chloride and bromide, combined with the strontium, radium, oxygen, and hydrogen isotopic compositions of the effluents reflect the composition of Marcellus Shale produced waters. The discharge of the effluent from the treatment facility increased downstream concentrations of chloride and bromide above background levels. Barium and radium were substantially (>90%) reduced in the treated effluents compared to concentrations in Marcellus Shale produced waters. Nonetheless, (226)Ra levels in stream sediments (544-8759 Bq/kg) at the point of discharge were ~200 times greater than upstream and background sediments (22-44 Bq/kg) and above radioactive waste disposal threshold regulations, posing potential environmental risks of radium bioaccumulation in localized areas of shale gas wastewater disposal.

    View details for DOI 10.1021/es402165b

    View details for Web of Science ID 000326123600060

    View details for PubMedID 24087919

  • Shale Gas Extraction in North Carolina: Research Recommendations and Public Health Implications ENVIRONMENTAL HEALTH PERSPECTIVES Down, A., Armes, M., Jackson, R. B. 2013; 121 (10): A292-A293

    View details for DOI 10.1289/ehp.1307402

    View details for Web of Science ID 000325152400001

    View details for PubMedID 24218671

    View details for PubMedCentralID PMC3801474

  • Increasing atmospheric CO2 reduces metabolic and physiological differences between isoprene- and non-isoprene-emitting poplars NEW PHYTOLOGIST Way, D. A., Ghirardo, A., Kanawati, B., Esperschuetz, J., Monson, R. K., Jackson, R. B., Schmitt-Kopplin, P., Schnitzler, J. 2013; 200 (2): 534-546


    Isoprene, a volatile organic compound produced by some plant species, enhances abiotic stress tolerance under current atmospheric CO2 concentrations, but its biosynthesis is negatively correlated with CO2 concentrations. We hypothesized that losing the capacity to produce isoprene would require stronger up-regulation of other stress tolerance mechanisms at low CO2 than at higher CO2 concentrations. We compared metabolite profiles and physiological performance in poplars (Populus × canescens) with either wild-type or RNAi-suppressed isoprene emission capacity grown at pre-industrial low, current atmospheric, and future high CO2 concentrations (190, 390 and 590 ppm CO2 , respectively). Suppression of isoprene biosynthesis led to significant rearrangement of the leaf metabolome, increasing stress tolerance responses such as xanthophyll cycle pigment de-epoxidation and antioxidant levels, as well as altering lipid, carbon and nitrogen metabolism. Metabolic and physiological differences between isoprene-emitting and suppressed lines diminished as growth CO2 concentrations rose. The CO2 dependence of our results indicates that the effects of isoprene biosynthesis are strongest at pre-industrial CO2 concentrations. Rising CO2 may reduce the beneficial effects of biogenic isoprene emission, with implications for species competition. This has potential consequences for future climate warming, as isoprene emitted from vegetation has strong effects on global atmospheric chemistry.

    View details for DOI 10.1111/nph.12391

    View details for Web of Science ID 000324621600024

  • COMMENTARY: China's synthetic natural gas revolution NATURE CLIMATE CHANGE Yang, C., Jackson, R. B. 2013; 3 (10): 852-854
  • Geochemical and isotopic variations in shallow groundwater in areas of the Fayetteville Shale development, north-central Arkansas APPLIED GEOCHEMISTRY Warner, N. R., Kresse, T. M., Hays, P. D., Down, A., Karr, J. D., Jackson, R. B., Vengosh, A. 2013; 35: 207-220
  • Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Jackson, R. B., Vengosh, A., Darrah, T. H., Warner, N. R., Down, A., Poreda, R. J., Osborn, S. G., Zhao, K., Karr, J. D. 2013; 110 (28): 11250-11255


    Horizontal drilling and hydraulic fracturing are transforming energy production, but their potential environmental effects remain controversial. We analyzed 141 drinking water wells across the Appalachian Plateaus physiographic province of northeastern Pennsylvania, examining natural gas concentrations and isotopic signatures with proximity to shale gas wells. Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes <1 km from natural gas wells (P = 0.0006). Ethane was 23 times higher in homes <1 km from gas wells (P = 0.0013); propane was detected in 10 water wells, all within approximately 1 km distance (P = 0.01). Of three factors previously proposed to influence gas concentrations in shallow groundwater (distances to gas wells, valley bottoms, and the Appalachian Structural Front, a proxy for tectonic deformation), distance to gas wells was highly significant for methane concentrations (P = 0.007; multiple regression), whereas distances to valley bottoms and the Appalachian Structural Front were not significant (P = 0.27 and P = 0.11, respectively). Distance to gas wells was also the most significant factor for Pearson and Spearman correlation analyses (P < 0.01). For ethane concentrations, distance to gas wells was the only statistically significant factor (P < 0.005). Isotopic signatures (δ(13)C-CH4, δ(13)C-C2H6, and δ(2)H-CH4), hydrocarbon ratios (methane to ethane and propane), and the ratio of the noble gas (4)He to CH4 in groundwater were characteristic of a thermally postmature Marcellus-like source in some cases. Overall, our data suggest that some homeowners living <1 km from gas wells have drinking water contaminated with stray gases.

    View details for DOI 10.1073/pnas.1221635110

    View details for Web of Science ID 000321827000027

    View details for PubMedID 23798404

    View details for PubMedCentralID PMC3710833

  • Hydraulic limits on maximum plant transpiration and the emergence of the safety-efficiency trade-off NEW PHYTOLOGIST Manzoni, S., Vico, G., Katul, G., Palmroth, S., Jackson, R. B., Porporato, A. 2013; 198 (1): 169-178


    Soil and plant hydraulics constrain ecosystem productivity by setting physical limits to water transport and hence carbon uptake by leaves. While more negative xylem water potentials provide a larger driving force for water transport, they also cause cavitation that limits hydraulic conductivity. An optimum balance between driving force and cavitation occurs at intermediate water potentials, thus defining the maximum transpiration rate the xylem can sustain (denoted as E(max)). The presence of this maximum raises the question as to whether plants regulate transpiration through stomata to function near E(max). To address this question, we calculated E(max) across plant functional types and climates using a hydraulic model and a global database of plant hydraulic traits. The predicted E(max) compared well with measured peak transpiration across plant sizes and growth conditions (R = 0.86, P < 0.001) and was relatively conserved among plant types (for a given plant size), while increasing across climates following the atmospheric evaporative demand. The fact that E(max) was roughly conserved across plant types and scales with the product of xylem saturated conductivity and water potential at 50% cavitation was used here to explain the safety-efficiency trade-off in plant xylem. Stomatal conductance allows maximum transpiration rates despite partial cavitation in the xylem thereby suggesting coordination between stomatal regulation and xylem hydraulic characteristics.

    View details for DOI 10.1111/nph.12126

    View details for Web of Science ID 000315440400018

    View details for PubMedID 23356378

  • Mapping urban pipeline leaks: Methane leaks across Boston ENVIRONMENTAL POLLUTION Phillips, N. G., Ackley, R., Crosson, E. R., Down, A., Hutyra, L. R., Brondfield, M., Karr, J. D., Zhao, K., Jackson, R. B. 2013; 173: 1-4


    Natural gas is the largest source of anthropogenic emissions of methane (CH(4)) in the United States. To assess pipeline emissions across a major city, we mapped CH(4) leaks across all 785 road miles in the city of Boston using a cavity-ring-down mobile CH(4) analyzer. We identified 3356 CH(4) leaks with concentrations exceeding up to 15 times the global background level. Separately, we measured δ(13)CH(4) isotopic signatures from a subset of these leaks. The δ(13)CH(4) signatures (mean = -42.8‰ ± 1.3‰ s.e.; n = 32) strongly indicate a fossil fuel source rather than a biogenic source for most of the leaks; natural gas sampled across the city had average δ(13)CH(4) values of -36.8‰ (± 0.7‰ s.e., n = 10), whereas CH(4) collected from landfill sites, wetlands, and sewer systems had δ(13)CH(4) signatures ~20‰ lighter (μ = -57.8‰, ± 1.6‰ s.e., n = 8). Repairing leaky natural gas distribution systems will reduce greenhouse gas emissions, increase consumer health and safety, and save money.

    View details for DOI 10.1016/j.envpol.2012.11.003

    View details for Web of Science ID 000313845500001

    View details for PubMedID 23174345

  • The effects of shale gas exploration and hydraulic fracturing on the quality of water resources in the United States 14th International Symposium on Water-Rock Interaction (WRI) Vengosh, A., Warner, N., Jackson, R., Darrah, T. ELSEVIER SCIENCE BV. 2013: 863–866
  • Elevated growth temperatures alter hydraulic characteristics in trembling aspen (Populus tremuloides) seedlings: implications for tree drought tolerance PLANT CELL AND ENVIRONMENT Way, D. A., Domec, J., Jackson, R. B. 2013; 36 (1): 103-115


    Although climate change will alter both soil water availability and evaporative demand, our understanding of how future climate conditions will alter tree hydraulic architecture is limited. Here, we demonstrate that growth at elevated temperatures (ambient +5 °C) affects hydraulic traits in seedlings of the deciduous boreal tree species Populus tremuloides, with the strength of the effect varying with the plant organ studied. Temperature altered the partitioning of hydraulic resistance, with greater resistance attributed to stems and less to roots in warm-grown seedlings (P < 0.02), and a 46% (but marginally significant, P = 0.08) increase in whole plant conductance at elevated temperature. Vulnerability to cavitation was greater in leaves grown at high than at ambient temperatures, but vulnerability in stems was similar between treatments. A soil-plant-atmosphere (SPA) model suggests that these coordinated changes in hydraulic physiology would lead to more frequent drought stress and reduced water-use efficiency in aspen that develop at warmer temperatures. Tissue-specific trade-offs in hydraulic traits in response to high growth temperatures would be difficult to detect when relying solely on whole plant measurements, but may have large-scale ecological implications for plant water use, carbon cycling and, possibly, plant drought survival.

    View details for DOI 10.1111/j.1365-3040.2012.02557.x

    View details for Web of Science ID 000311974000007

    View details for PubMedID 22690910

  • The Structure, Distribution, and Biomass of the World's Forests ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS, VOL 44 Pan, Y., Birdsey, R. A., Phillips, O. L., Jackson, R. B. 2013; 44: 593-?
  • Reply to Engelder: Potential for fluid migration from the Marcellus Formation remains possible PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Warner, N. R., Jackson, R. B., Darrah, T. H., Osborn, S. G., Down, A., Zhao, K., White, A., Vengosh, A. 2012; 109 (52): E3626-E3626
  • China's coal price disturbances: Observations, explanations, and implications for global energy economies ENERGY POLICY Yang, C., Xuan, X., Jackson, R. B. 2012; 51: 720-727
  • Revised calibration of the MBT-CBT paleotemperature proxy based on branched tetraether membrane lipids in surface soils GEOCHIMICA ET COSMOCHIMICA ACTA Peterse, F., van der Meer, J., Schouten, S., Weijers, J. W., Fierer, N., Jackson, R. B., Kim, J., Damste, J. S. 2012; 96: 215-229
  • Assessing the potential of wildfires as a sustainable bioenergy opportunity GLOBAL CHANGE BIOLOGY BIOENERGY Veron, S. R., Jobbagy, E. G., Di Bella, C. M., Paruelo, J. M., Jackson, R. B. 2012; 4 (6): 634-641
  • Soil-mediated effects of subambient to increased carbon dioxide on grassland productivity NATURE CLIMATE CHANGE Fay, P. A., Jin, V. L., Way, D. A., Potter, K. N., Gill, R. A., Jackson, R. B., Polley, H. W. 2012; 2 (10): 742-746
  • Shifts in soil organic carbon for plantation and pasture establishment in native forests and grasslands of South America. Global change biology Eclesia, R. P., Jobbagy, E. G., Jackson, R. B., Biganzoli, F., Piñeiro, G. 2012; 18 (10): 3237-3251


    The replacement of native vegetation by pastures or tree plantations is increasing worldwide. Contradictory effects of these land use transitions on the direction of changes in soil organic carbon (SOC) stocks, quality, and vertical distribution have been reported, which could be explained by the characteristics of the new or prior vegetation, time since vegetation replacement, and environmental conditions. We used a series of paired-field experiments and a literature synthesis to evaluate how these factors affect SOC contents in transitions between tree- and grass-dominated (grazed) ecosystems in South America. Both our field and literature approaches showed that SOC changes (0-20 cm of depth) were independent of the initial native vegetation (forest, grassland, or savanna) but strongly dependent on the characteristics of the new vegetation (tree plantations or pastures), its age, and precipitation. Pasture establishment increased SOC contents across all our precipitation gradient and C gains were greater as pastures aged. In contrast, tree plantations increased SOC stocks in arid sites but decreased them in humid ones. However, SOC losses in humid sites were counterbalanced by the effect of plantation age, as plantations increased their SOC stocks as plantations aged. A multiple regression model including age and precipitation explained more than 50% (p < 0.01) of SOC changes observed after sowing pastures or planting trees. The only clear shift observed in the vertical distribution of SOC occurred when pastures replaced native forests, with SOC gains in the surface soil but losses at greater depths. The changes in SOC stocks occurred mainly in the silt+clay soil size fraction (MAOM), while SOC stocks in labile (POM) fraction remained relatively constant. Our results can be considered in designing strategies to increase SOC storage and soil fertility and highlight the importance of precipitation, soil depth, and age in determining SOC changes across a range of environments and land-use transitions.

    View details for DOI 10.1111/j.1365-2486.2012.02761.x

    View details for PubMedID 28741815

  • The impact of geologic variability on capacity and cost estimates for storing CO2 in deep-saline aquifers ENERGY ECONOMICS Eccles, J. K., Pratson, L., Newell, R. G., Jackson, R. B. 2012; 34 (5): 1569-1579
  • Geochemical evidence for possible natural migration of Marcellus Formation brine to shallow aquifers in Pennsylvania PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Warner, N. R., Jackson, R. B., Darrah, T. H., Osborn, S. G., Down, A., Zhao, K., White, A., Vengosh, A. 2012; 109 (30): 11961-11966


    The debate surrounding the safety of shale gas development in the Appalachian Basin has generated increased awareness of drinking water quality in rural communities. Concerns include the potential for migration of stray gas, metal-rich formation brines, and hydraulic fracturing and/or flowback fluids to drinking water aquifers. A critical question common to these environmental risks is the hydraulic connectivity between the shale gas formations and the overlying shallow drinking water aquifers. We present geochemical evidence from northeastern Pennsylvania showing that pathways, unrelated to recent drilling activities, exist in some locations between deep underlying formations and shallow drinking water aquifers. Integration of chemical data (Br, Cl, Na, Ba, Sr, and Li) and isotopic ratios ((87)Sr/(86)Sr, (2)H/H, (18)O/(16)O, and (228)Ra/(226)Ra) from this and previous studies in 426 shallow groundwater samples and 83 northern Appalachian brine samples suggest that mixing relationships between shallow ground water and a deep formation brine causes groundwater salinization in some locations. The strong geochemical fingerprint in the salinized (Cl > 20 mg/L) groundwater sampled from the Alluvium, Catskill, and Lock Haven aquifers suggests possible migration of Marcellus brine through naturally occurring pathways. The occurrences of saline water do not correlate with the location of shale-gas wells and are consistent with reported data before rapid shale-gas development in the region; however, the presence of these fluids suggests conductive pathways and specific geostructural and/or hydrodynamic regimes in northeastern Pennsylvania that are at increased risk for contamination of shallow drinking water resources, particularly by fugitive gases, because of natural hydraulic connections to deeper formations.

    View details for DOI 10.1073/pnas.1121181109

    View details for Web of Science ID 000306992700025

    View details for PubMedID 22778445

    View details for PubMedCentralID PMC3409753

  • The hydrologic consequences of land cover change in central Argentina AGRICULTURE ECOSYSTEMS & ENVIRONMENT Nosetto, M. D., Jobbagy, E. G., Brizuela, A. B., Jackson, R. B. 2012; 154: 2-11
  • Analytical models of soil and litter decomposition: Solutions for mass loss and time-dependent decay rates SOIL BIOLOGY & BIOCHEMISTRY Manzoni, S., Pineiro, G., Jackson, R. B., Jobbagy, E. G., Kim, J. H., Porporato, A. 2012; 50: 66-76
  • Ecosystem Impacts of Geoengineering: A Review for Developing a Science Plan AMBIO Russell, L. M., Rasch, P. J., Mace, G. M., Jackson, R. B., Shepherd, J., Liss, P., Leinen, M., Schimel, D., Vaughan, N. E., Janetos, A. C., Boyd, P. W., Norby, R. J., Caldeira, K., Merikanto, J., Artaxo, P., Melillo, J., Morgan, M. G. 2012; 41 (4): 350-369


    Geoengineering methods are intended to reduce climate change, which is already having demonstrable effects on ecosystem structure and functioning in some regions. Two types of geoengineering activities that have been proposed are: carbon dioxide (CO(2)) removal (CDR), which removes CO(2) from the atmosphere, and solar radiation management (SRM, or sunlight reflection methods), which reflects a small percentage of sunlight back into space to offset warming from greenhouse gases (GHGs). Current research suggests that SRM or CDR might diminish the impacts of climate change on ecosystems by reducing changes in temperature and precipitation. However, sudden cessation of SRM would exacerbate the climate effects on ecosystems, and some CDR might interfere with oceanic and terrestrial ecosystem processes. The many risks and uncertainties associated with these new kinds of purposeful perturbations to the Earth system are not well understood and require cautious and comprehensive research.

    View details for DOI 10.1007/s13280-012-0258-5

    View details for Web of Science ID 000304617700004

    View details for PubMedID 22430307

    View details for PubMedCentralID PMC3393062

  • Global resorption efficiencies and concentrations of carbon and nutrients in leaves of terrestrial plants ECOLOGICAL MONOGRAPHS Vergutz, L., Manzoni, S., Porporato, A., Novais, R. F., Jackson, R. B. 2012; 82 (2): 205-220
  • Common bacterial responses in six ecosystems exposed to 10 years of elevated atmospheric carbon dioxide ENVIRONMENTAL MICROBIOLOGY Dunbar, J., Eichorst, S. A., Gallegos-Graves, L. V., Silva, S., Xie, G., Hengartner, N. W., Evans, R. D., Hungate, B. A., Jackson, R. B., Megonigal, J. P., Schadt, C. W., Vilgalys, R., Zak, D. R., Kuske, C. R. 2012; 14 (5): 1145-1158


    Six terrestrial ecosystems in the USA were exposed to elevated atmospheric CO(2) in single or multifactorial experiments for more than a decade to assess potential impacts. We retrospectively assessed soil bacterial community responses in all six-field experiments and found ecosystem-specific and common patterns of soil bacterial community response to elevated CO(2) . Soil bacterial composition differed greatly across the six ecosystems. No common effect of elevated atmospheric CO(2) on bacterial biomass, richness and community composition across all of the ecosystems was identified, although significant responses were detected in individual ecosystems. The most striking common trend across the sites was a decrease of up to 3.5-fold in the relative abundance of Acidobacteria Group 1 bacteria in soils exposed to elevated CO(2) or other climate factors. The Acidobacteria Group 1 response observed in exploratory 16S rRNA gene clone library surveys was validated in one ecosystem by 100-fold deeper sequencing and semi-quantitative PCR assays. Collectively, the 16S rRNA gene sequencing approach revealed influences of elevated CO(2) on multiple ecosystems. Although few common trends across the ecosystems were detected in the small surveys, the trends may be harbingers of more substantive changes in less abundant, more sensitive taxa that can only be detected by deeper surveys. Representative bacterial 16S rRNA gene clone sequences were deposited in GenBank with Accession No. JQ366086–JQ387568.

    View details for DOI 10.1111/j.1462-2920.2011.02695.x

    View details for Web of Science ID 000302934000004

    View details for PubMedID 22264231

  • Conversion of Tallgrass Prairie to Woodland: Consequences for Carbon and Nitrogen Cycling AMERICAN MIDLAND NATURALIST McCulley, R. L., Jackson, R. B. 2012; 167 (2): 307-321
  • The potential of waste-to-energy in reducing GHG emissions CARBON MANAGEMENT Chandel, M. K., Kwok, G., Jackson, R. B., Pratson, L. F. 2012; 3 (2): 133-144

    View details for DOI 10.4155/CMT.12.11

    View details for Web of Science ID 000315238200010

  • Contribution of Various Carbon Sources Toward Isoprene Biosynthesis in Poplar Leaves Mediated by Altered Atmospheric CO2 Concentrations PLOS ONE Trowbridge, A. M., Asensio, D., Eller, A. S., Way, D. A., Wilkinson, M. J., Schnitzler, J., Jackson, R. B., Monson, R. K. 2012; 7 (2)


    Biogenically released isoprene plays important roles in both tropospheric photochemistry and plant metabolism. We performed a (13)CO(2)-labeling study using proton-transfer-reaction mass spectrometry (PTR-MS) to examine the kinetics of recently assimilated photosynthate into isoprene emitted from poplar (Populus × canescens) trees grown and measured at different atmospheric CO(2) concentrations. This is the first study to explicitly consider the effects of altered atmospheric CO(2) concentration on carbon partitioning to isoprene biosynthesis. We studied changes in the proportion of labeled carbon as a function of time in two mass fragments, M41(+), which represents, in part, substrate derived from pyruvate, and M69(+), which represents the whole unlabeled isoprene molecule. We observed a trend of slower (13)C incorporation into isoprene carbon derived from pyruvate, consistent with the previously hypothesized origin of chloroplastic pyruvate from cytosolic phosphenolpyruvate (PEP). Trees grown under sub-ambient CO(2) (190 ppmv) had rates of isoprene emission and rates of labeling of M41(+) and M69(+) that were nearly twice those observed in trees grown under elevated CO(2) (590 ppmv). However, they also demonstrated the lowest proportion of completely labeled isoprene molecules. These results suggest that under reduced atmospheric CO(2) availability, more carbon from stored/older carbon sources is involved in isoprene biosynthesis, and this carbon most likely enters the isoprene biosynthesis pathway through the pyruvate substrate. We offer direct evidence that extra-chloroplastic rather than chloroplastic carbon sources are mobilized to increase the availability of pyruvate required to up-regulate the isoprene biosynthesis pathway when trees are grown under sub-ambient CO(2).

    View details for DOI 10.1371/journal.pone.0032387

    View details for Web of Science ID 000302916100077

    View details for PubMedID 22384238

    View details for PubMedCentralID PMC3285681

  • A Global Analysis of Groundwater Recharge for Vegetation, Climate, and Soils VADOSE ZONE JOURNAL Kim, J. H., Jackson, R. B. 2012; 11 (1)
  • N-2 fixation estimates in real-time by cavity ring-down laser absorption spectroscopy OECOLOGIA Cassar, N., Bellenger, J., Jackson, R. B., Karr, J., Barnett, B. A. 2012; 168 (2): 335-342


    The most common currency for estimating N(2) fixation is acetylene reduction to ethylene. Real-time estimates of nitrogen fixation are needed to close the global nitrogen budget and these remain a critical gap in both laboratory and field experiments. We present a new method for continuous real-time measurements of ethylene production: Acetylene Reduction Assays by Cavity ring-down laser Absorption Spectroscopy (ARACAS). In ARACAS, air in the headspace of an incubation chamber is circulated with a diaphragm pump through a cavity ring-down ethylene spectrometer and back to the incubation chamber. This paper describes the new approach and its benefits compared to the conventional detection of ethylene by flame ionization detector gas chromatography. First, the detection of acetylene reduction to ethylene is non-intrusive and chemically non-destructive, allowing for real-time measurements of nitrogenase activity. Second, the measurements are made instantaneously and continuously at ppb levels, allowing for observation of real-time kinetics on time intervals as short as a few seconds. Third, the instrument can be automated for long time periods of measurement. Finally, the technique will be widely accessible by the research community as it can be readily adapted to most existing acetylene reduction protocols and is based on a modestly priced, commercially available instrument. We illustrate its use for measuring N(2) fixation using two species, the diazotrophic bacterium Azotobacter vinelandii and the lichen Peltigera praetextata. We also discuss potential limitations of the approach, primarily the implications of leaks in the analyzer, as well as future improvements.

    View details for DOI 10.1007/s00442-011-2105-y

    View details for Web of Science ID 000301705700004

    View details for PubMedID 21879367

  • China's growing methanol economy and its implications for energy and the environment ENERGY POLICY Yang, C., Jackson, R. B. 2012; 41: 878-884
  • The carbon balance of South America: a review of the status, decadal trends and main determinants BIOGEOSCIENCES Gloor, M., Gatti, L., Brienen, R., Feldpausch, T. R., Phillips, O. L., Miller, J., Ometto, J. P., ROCHA, H., Baker, T., de Jong, B., Houghton, R. A., Malhi, Y., Aragao, L. E., Guyot, J., Zhao, K., Jackson, R., Peylin, P., Sitch, S., Poulter, B., Lomas, M., Zaehle, S., Huntingford, C., Levy, P., Lloyd, J. 2012; 9 (12): 5407-5430
  • The effect of hydraulic lift on organic matter decomposition, soil nitrogen cycling, and nitrogen acquisition by a grass species OECOLOGIA Armas, C., Kim, J. H., Bleby, T. M., Jackson, R. B. 2012; 168 (1): 11-22


    Hydraulic lift (HL) is the passive movement of water through plant roots, driven by gradients in water potential. The greater soil-water availability resulting from HL may in principle lead to higher plant nutrient uptake, but the evidence for this hypothesis is not universally supported by current experiments. We grew a grass species common in North America in two-layer pots with three treatments: (1) the lower layer watered, the upper one unwatered (HL), (2) both layers watered (W), and (3) the lower layer watered, the upper one unwatered, but with continuous light 24 h a day to limit HL (no-HL). We inserted ingrowth cores filled with enriched-nitrogen organic matter ((15)N-OM) in the upper layer and tested whether decomposition, mineralization and uptake of (15)N were higher in plants performing HL than in plants without HL. Soils in the upper layer were significantly wetter in the HL treatment than in the no-HL treatment. Decomposition rates were similar in the W and HL treatments and lower in no-HL. On average, the concentration of NH(4)(+)-N in ingrowth cores was highest in the W treatment, and NO(3)(-)-N concentrations were highest in the no-HL treatment, with HL having intermediate values for both, suggesting differential mineralization of organic N among treatments. Aboveground biomass, leaf (15)N contents and the (15)N uptake in aboveground tissues were higher in W and HL than in no-HL, indicating higher nutrient uptake and improved N status of plants performing HL. However, there were no differences in total root nitrogen content or (15)N uptake by roots, indicating that HL affected plant allocation of acquired N to photosynthetic tissues. Our evidence for the role of HL in organic matter decomposition and nutrient cycling suggests that HL could have positive effects on plant nutrient dynamics and nutrient turnover.

    View details for DOI 10.1007/s00442-011-2065-2

    View details for Web of Science ID 000299058100002

    View details for PubMedID 21766189

  • Shallow groundwater quality and geochemistry in the Fayetteville Shale gas-production area, north-central Arkansas, 2011. U.S. Geological Survey Scientific Investigations Report 2012–5273 Kresse, T., Warner, N. R., Hays, P. D., Down, A., Vengosh, A., Jackson, R. B. 2012; 2012–5273
  • Soil C and N changes with afforestation of grasslands across gradients of precipitation and plantation age ECOLOGICAL APPLICATIONS Berthrong, S. T., Pineiro, G., Jobbagy, E. G., Jackson, R. B. 2012; 22 (1): 76-86


    Afforestation, the conversion of unforested lands to forests, is a tool for sequestering anthropogenic carbon dioxide into plant biomass. However, in addition to altering biomass, afforestation can have substantial effects on soil organic carbon (SOC) pools, some of which have much longer turnover times than plant biomass. An increasing body of evidence suggests that the effect of afforestation on SOC may depend on mean annual precipitation (MAP). The goal of this study was to test how labile and bulk pools of SOC and total soil nitrogen (TN) change with afforestation across a rainfall gradient of 600-1500 mm in the Rio de la Plata grasslands of Argentina and Uruguay. The sites were all former grasslands planted with Eucalyptus spp. Overall, we found that afforestation increased (up to 1012 kg C x ha(-1) x yr(-1)) or decreased (as much as 1294 kg C x ha(-1) x yr(-1)) SOC pools in this region and that these changes were significantly related to MAP. Drier sites gained, and wetter sites lost, SOC and TN (r2 = 0.59, P = 0.003; and r2 = 0.57, P = 0.004, respectively). Labile C and N in microbial biomass and extractable soil pools followed similar patterns to bulk SOC and TN. Interestingly, drier sites gained more SOC and TN as plantations aged, while losses reversed as plantations aged in wet sites, suggesting that plantation age in addition to precipitation is a critical driver of changes in soil organic matter with afforestation. This new evidence implies that longer intervals between harvests for plantations could improve SOC storage, ameliorating the negative trends found in humid sites. Our results suggest that the value of afforestation as a carbon sequestration tool should be considered in the context of precipitation and age of the forest stand.

    View details for Web of Science ID 000301095600007

    View details for PubMedID 22471076

  • Considering shale gas extraction in North Carolina: lessons from other states Duke Environmental Law and Policy Forum Adair, S., Rainey Pearson, B., Monast, J., Vengosh, A., Jackson, R. B. 2012; 22:257-301
  • Beyond Bacteria: A Study of the Enteric Microbial Consortium in Extremely Low Birth Weight Infants PLOS ONE Latuga, M. S., Ellis, J. C., Cotton, C. M., Goldberg, R. N., Wynn, J. L., Jackson, R. B., Seed, P. C. 2011; 6 (12)


    Extremely low birth weight (ELBW) infants have high morbidity and mortality, frequently due to invasive infections from bacteria, fungi, and viruses. The microbial communities present in the gastrointestinal tracts of preterm infants may serve as a reservoir for invasive organisms and remain poorly characterized. We used deep pyrosequencing to examine the gut-associated microbiome of 11 ELBW infants in the first postnatal month, with a first time determination of the eukaryote microbiota such as fungi and nematodes, including bacteria and viruses that have not been previously described. Among the fungi observed, Candida sp. and Clavispora sp. dominated the sequences, but a range of environmental molds were also observed. Surprisingly, seventy-one percent of the infant fecal samples tested contained ribosomal sequences corresponding to the parasitic organism Trichinella. Ribosomal DNA sequences for the roundworm symbiont Xenorhabdus accompanied these sequences in the infant with the greatest proportion of Trichinella sequences. When examining ribosomal DNA sequences in aggregate, Enterobacteriales, Pseudomonas, Staphylococcus, and Enterococcus were the most abundant bacterial taxa in a low diversity bacterial community (mean Shannon-Weaver Index of 1.02 ± 0.69), with relatively little change within individual infants through time. To supplement the ribosomal sequence data, shotgun sequencing was performed on DNA from multiple displacement amplification (MDA) of total fecal genomic DNA from two infants. In addition to the organisms mentioned previously, the metagenome also revealed sequences for gram positive and gram negative bacteriophages, as well as human adenovirus C. Together, these data reveal surprising eukaryotic and viral microbial diversity in ELBW enteric microbiota dominated bytypes of bacteria known to cause invasive disease in these infants.

    View details for DOI 10.1371/journal.pone.0027858

    View details for Web of Science ID 000298163600007

    View details for PubMedID 22174751

    View details for PubMedCentralID PMC3234235

  • Sources of increased N uptake in forest trees growing under elevated CO2: results of a large-scale N-15 study GLOBAL CHANGE BIOLOGY Hofmockel, K. S., Gallet-Budynek, A., McCarthy, H. R., Currie, W. S., Jackson, R. B., Finzi, A. C. 2011; 17 (11): 3338-3350
  • Reply to Davies: Hydraulic fracturing remains a possible mechanism for observed methane contamination of drinking water PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Jackson, R. B., Osborn, S. G., Vengosh, A., Warner, N. R. 2011; 108 (43): E872-E872
  • Changes in hydrology and salinity accompanying a century of agricultural conversion in Argentina ECOLOGICAL APPLICATIONS Jayawickreme, D. H., Santoni, C. S., Kim, J. H., Jobbagy, E. G., Jackson, R. B. 2011; 21 (7): 2367-2379


    Conversions of natural woodlands to agriculture can alter the hydrologic balance, aquifer recharge, and salinity of soils and groundwater in ways that influence productivity and sustainable land use. Using a land-use change chronosequence in semiarid woodlands of Argentina's Espinal province, we examined the distribution of moisture and solutes and estimated recharge rates on adjacent plots of native woodlands and rain-fed agriculture converted 6-90 years previously. Soil coring and geoelectrical profiling confirmed the presence of spatially extensive salt accumulations in dry woodlands and pervasive salt losses in areas converted to agriculture. A 1.1-km-long electrical resistivity transect traversing woodland, 70-year-old agriculture, and woodland, for instance, revealed a low-resistivity (high-salinity) horizon between approximately 3 m and 13 m depth in the woodlands that was virtually absent in the agricultural site because of leaching. Nine-meter-deep soil profiles indicated a 53% increase in soil water storage after 30 or more years of cultivation. Conservative groundwater-recharge estimates based on chloride tracer methods in agricultural plots ranged from approximately 12 to 45 mm/yr, a substantial increase from the <1 mm/yr recharge in dry woodlands. The onset of deep soil moisture drainage and increased recharge led to >95% loss of sulfate and chloride ions from the shallow vadose zone in most agriculture plots. These losses correspond to over 100 Mg of sulfate and chloride salts potentially released to the region's groundwater aquifers through time with each hectare of deforestation, including a capacity to increase groundwater salinity to >4000 mg/L from these ions alone. Similarities between our findings and those of the dryland salinity problems of deforested woodlands in Australia suggest an important warning about the potential ecohydrological risks brought by the current wave of deforestation in the Espinal and other regions of South America and the world.

    View details for Web of Science ID 000296139200003

    View details for PubMedID 22073629

  • Responses of soil cellulolytic fungal communities to elevated atmospheric CO2 are complex and variable across five ecosystems ENVIRONMENTAL MICROBIOLOGY Weber, C. F., Zak, D. R., Hungate, B. A., Jackson, R. B., Vilgalys, R., Evans, R. D., Schadt, C. W., Megonigal, J. P., Kuske, C. R. 2011; 13 (10): 2778-2793


    Elevated atmospheric CO(2) generally increases plant productivity and subsequently increases the availability of cellulose in soil to microbial decomposers. As key cellulose degraders, soil fungi are likely to be one of the most impacted and responsive microbial groups to elevated atmospheric CO(2). To investigate the impacts of ecosystem type and elevated atmospheric CO(2) on cellulolytic fungal communities, we sequenced 10,677 cbhI gene fragments encoding the catalytic subunit of cellobiohydrolase I, across five distinct terrestrial ecosystem experiments after a decade of exposure to elevated CO(2). The cbhI composition of each ecosystem was distinct, as supported by weighted Unifrac analyses (all P-values; < 0.001), with few operational taxonomic units (OTUs) being shared across ecosystems. Using a 114-member cbhI sequence database compiled from known fungi, less than 1% of the environmental sequences could be classified at the family level indicating that cellulolytic fungi in situ are likely dominated by novel fungi or known fungi that are not yet recognized as cellulose degraders. Shifts in fungal cbhI composition and richness that were correlated with elevated CO(2) exposure varied across the ecosystems. In aspen plantation and desert creosote bush soils, cbhI gene richness was significantly higher after exposure to elevated CO(2) (550 µmol mol(-1)) than under ambient CO(2) (360 µmol mol(-1) CO(2)). In contrast, while the richness was not altered, the relative abundance of dominant OTUs in desert soil crusts was significantly shifted. This suggests that responses are complex, vary across different ecosystems and, in at least one case, are OTU-specific. Collectively, our results document the complexity of cellulolytic fungal communities in multiple terrestrial ecosystems and the variability of their responses to long-term exposure to elevated atmospheric CO(2).

    View details for DOI 10.1111/j.1462-2920.2011.02548.x

    View details for Web of Science ID 000295971300014

    View details for PubMedID 21883796

  • The potential impacts of climate-change policy on freshwater use in thermoelectric power generation ENERGY POLICY Chandel, M. K., Pratson, L. F., Jackson, R. B. 2011; 39 (10): 6234-6242
  • Reply to Saba and Orzechowski and Schon: Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Osborn, S. G., Vengosh, A., Warner, N. R., Jackson, R. B. 2011; 108 (37): E665-E666
  • A synthesis of current knowledge on forests and carbon storage in the United States ECOLOGICAL APPLICATIONS McKinley, D. C., Ryan, M. G., Birdsey, R. A., Giardina, C. P., Harmon, M. E., Heath, L. S., Houghton, R. A., Jackson, R. B., Morrison, J. F., Murray, B. C., Pataki, D. E., Skog, K. E. 2011; 21 (6): 1902-1924


    Using forests to mitigate climate change has gained much interest in science and policy discussions. We examine the evidence for carbon benefits, environmental and monetary costs, risks and trade-offs for a variety of activities in three general strategies: (1) land use change to increase forest area (afforestation) and avoid deforestation; (2) carbon management in existing forests; and (3) the use of wood as biomass energy, in place of other building materials, or in wood products for carbon storage. We found that many strategies can increase forest sector carbon mitigation above the current 162-256 Tg C/yr, and that many strategies have co-benefits such as biodiversity, water, and economic opportunities. Each strategy also has trade-offs, risks, and uncertainties including possible leakage, permanence, disturbances, and climate change effects. Because approximately 60% of the carbon lost through deforestation and harvesting from 1700 to 1935 has not yet been recovered and because some strategies store carbon in forest products or use biomass energy, the biological potential for forest sector carbon mitigation is large. Several studies suggest that using these strategies could offset as much as 10-20% of current U.S. fossil fuel emissions. To obtain such large offsets in the United States would require a combination of afforesting up to one-third of cropland or pastureland, using the equivalent of about one-half of the gross annual forest growth for biomass energy, or implementing more intensive management to increase forest growth on one-third of forestland. Such large offsets would require substantial trade-offs, such as lower agricultural production and non-carbon ecosystem services from forests. The effectiveness of activities could be diluted by negative leakage effects and increasing disturbance regimes. Because forest carbon loss contributes to increasing climate risk and because climate change may impede regeneration following disturbance, avoiding deforestation and promoting regeneration after disturbance should receive high priority as policy considerations. Policies to encourage programs or projects that influence forest carbon sequestration and offset fossil fuel emissions should also consider major items such as leakage, the cyclical nature of forest growth and regrowth, and the extensive demand for and movement of forest products globally, and other greenhouse gas effects, such as methane and nitrous oxide emissions, and recognize other environmental benefits of forests, such as biodiversity, nutrient management, and watershed protection. Activities that contribute to helping forests adapt to the effects of climate change, and which also complement forest carbon storage strategies, would be prudent.

    View details for Web of Science ID 000294155900003

    View details for PubMedID 21939033

  • A Large and Persistent Carbon Sink in the World's Forests SCIENCE Pan, Y., Birdsey, R. A., Fang, J., Houghton, R., Kauppi, P. E., Kurz, W. A., Phillips, O. L., Shvidenko, A., Lewis, S. L., Canadell, J. G., Ciais, P., Jackson, R. B., Pacala, S. W., McGuire, A. D., Piao, S., Rautiainen, A., Sitch, S., Hayes, D. 2011; 333 (6045): 988-993


    The terrestrial carbon sink has been large in recent decades, but its size and location remain uncertain. Using forest inventory data and long-term ecosystem carbon studies, we estimate a total forest sink of 2.4 ± 0.4 petagrams of carbon per year (Pg C year(-1)) globally for 1990 to 2007. We also estimate a source of 1.3 ± 0.7 Pg C year(-1) from tropical land-use change, consisting of a gross tropical deforestation emission of 2.9 ± 0.5 Pg C year(-1) partially compensated by a carbon sink in tropical forest regrowth of 1.6 ± 0.5 Pg C year(-1). Together, the fluxes comprise a net global forest sink of 1.1 ± 0.8 Pg C year(-1), with tropical estimates having the largest uncertainties. Our total forest sink estimate is equivalent in magnitude to the terrestrial sink deduced from fossil fuel emissions and land-use change sources minus ocean and atmospheric sinks.

    View details for DOI 10.1126/science.1201609

    View details for Web of Science ID 000294000400048

    View details for PubMedID 21764754

  • Atmospheric CO2 and soil extracellular enzyme activity: a meta-analysis and CO2 gradient experiment ECOSPHERE Kelley, A. M., Fay, P. A., Polley, H. W., Gill, R. A., Jackson, R. B. 2011; 2 (8)
  • Earth Stewardship: science for action to sustain the human-earth system ECOSPHERE Chapin, F. S., Power, M. E., Pickett, S. T., Freitag, A., Reynolds, J. A., Jackson, R. B., Lodge, D. M., Duke, C., Collins, S. L., Power, A. G., Bartuska, A. 2011; 2 (8)
  • Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Osborn, S. G., Vengosh, A., Warner, N. R., Jackson, R. B. 2011; 108 (20): 8172-8176


    Directional drilling and hydraulic-fracturing technologies are dramatically increasing natural-gas extraction. In aquifers overlying the Marcellus and Utica shale formations of northeastern Pennsylvania and upstate New York, we document systematic evidence for methane contamination of drinking water associated with shale-gas extraction. In active gas-extraction areas (one or more gas wells within 1 km), average and maximum methane concentrations in drinking-water wells increased with proximity to the nearest gas well and were 19.2 and 64 mg CH(4) L(-1) (n = 26), a potential explosion hazard; in contrast, dissolved methane samples in neighboring nonextraction sites (no gas wells within 1 km) within similar geologic formations and hydrogeologic regimes averaged only 1.1 mg L(-1) (P < 0.05; n = 34). Average δ(13)C-CH(4) values of dissolved methane in shallow groundwater were significantly less negative for active than for nonactive sites (-37 ± 7‰ and -54 ± 11‰, respectively; P < 0.0001). These δ(13)C-CH(4) data, coupled with the ratios of methane-to-higher-chain hydrocarbons, and δ(2)H-CH(4) values, are consistent with deeper thermogenic methane sources such as the Marcellus and Utica shales at the active sites and matched gas geochemistry from gas wells nearby. In contrast, lower-concentration samples from shallow groundwater at nonactive sites had isotopic signatures reflecting a more biogenic or mixed biogenic/thermogenic methane source. We found no evidence for contamination of drinking-water samples with deep saline brines or fracturing fluids. We conclude that greater stewardship, data, and-possibly-regulation are needed to ensure the sustainable future of shale-gas extraction and to improve public confidence in its use.

    View details for DOI 10.1073/pnas.1100682108

    View details for Web of Science ID 000290719600025

    View details for PubMedID 21555547

    View details for PubMedCentralID PMC3100993

  • Enhanced isoprene-related tolerance of heat- and light-stressed photosynthesis at low, but not high, CO2 concentrations OECOLOGIA Way, D. A., Schnitzler, J., Monson, R. K., Jackson, R. B. 2011; 166 (1): 273-282


    The principal function of isoprene biosynthesis in plants remains unclear, but emission rates are positively correlated with temperature and light, supporting a role for isoprene in maintaining photosynthesis under transient heat and light stress from sunflecks. Isoprene production is also inversely correlated with CO(2) concentrations, implying that rising CO(2) may reduce the functional importance of isoprene. To understand the importance of isoprene in maintaining photosynthesis during sunflecks, we used RNAi technology to suppress isoprene production in poplar seedlings and compared the responses of these transgenic plants to wild-type and empty-vector control plants. We grew isoprene-emitting and non-emitting trees at low (190 ppm) and high (590 ppm) CO(2) concentrations and compared their photosynthetic responses to short, transient periods of high light and temperature, as well as their photosynthetic thermal response at constant light. While there was little difference between emitting and non-emitting plants in their photosynthetic responses to simulated sunflecks at high CO(2), isoprene-emitting trees grown at low CO(2) had significantly greater photosynthetic sunfleck tolerance than non-emitting plants. Net photosynthesis at 42°C was 50% lower in non-emitters than in isoprene-emitting trees at low CO(2), but only 22% lower at high CO(2). Dark respiration rates were significantly higher in non-emitting poplar from low CO(2), but there was no difference between isoprene-emitting and non-emitting lines at high CO(2). We propose that isoprene biosynthesis may have evolved at low CO(2) concentrations, where its physiological effect is greatest, and that rising CO(2) will reduce the functional benefit of isoprene in the near future.

    View details for DOI 10.1007/s00442-011-1947-7

    View details for Web of Science ID 000289442000026

    View details for PubMedID 21380850

  • Biophysical considerations in forestry for climate protection FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Anderson, R. G., Canadell, J. G., Randerson, J. T., Jackson, R. B., Hungate, B. A., Baldocchi, D. D., Ban-Weiss, G. A., Bonan, G. B., Caldeira, K., Cao, L., Diffenbaugh, N. S., Gurney, K. R., Kueppers, L. M., Law, B. E., Luyssaert, S., O'Halloran, T. L. 2011; 9 (3): 174-182

    View details for DOI 10.1890/090179

    View details for Web of Science ID 000289377800019

  • Response to Comment on "Potential Impacts of Leakage from Deep CO2 Geosequestration on Overlying Freshwater Aquifers" ENVIRONMENTAL SCIENCE & TECHNOLOGY Little, M. G., Jackson, R. B. 2011; 45 (7): 3175-3176

    View details for DOI 10.1021/es200421f

    View details for Web of Science ID 000288841500100

  • Water subsidies from mountains to deserts: their role in sustaining groundwater-fed oases in a sandy landscape ECOLOGICAL APPLICATIONS Jobbagy, E. G., Nosetto, M. D., Villagra, P. E., Jackson, R. B. 2011; 21 (3): 678-694


    In arid regions throughout the world, shallow phreatic aquifers feed natural oases of much higher productivity than would be expected solely from local rainfall. In South America, the presence of well-developed Prosopis flexuosa woodlands in the Monte Desert region east of the Andes has puzzled scientists for decades. Today these woodlands provide crucial subsistence to local populations, including descendants of the indigenous Huarpes. We explore the vulnerability and importance of phreatic groundwater for the productivity of the region, comparing the contributions of local rainfall to that of remote mountain recharge that is increasingly being diverted for irrigated agriculture before it reaches the desert. We combined deep soil coring, plant measurements, direct water-table observations, and stable-isotopic analyses (2H and 18O) of meteoric, surface, and ground waters at three study sites across the region, comparing woodland stands, bare dunes, and surrounding shrublands. The isotopic composition of phreatic groundwaters (delta2H: -137 per thousand +/- 5 per thousand) closely matched the signature of water brought to the region by the Mendoza River (-137 per thousand +/- 6 per thousand), suggestin that mountain-river infiltration rather than in situ rainfall deep drainage (-39 per thousand +/- 19 per thousand) was the dominant mechanism of recharge. Similarly, chloride mass balances determined from deep soil profiles (> 6 m) suggested very low recharge rates. Vegetation in woodland ecosystems, where significant groundwater discharge losses, likely >100 mm/yr occurred, relied on regionally derived groundwater located from 6.5 to 9.5 m underground. At these locations, daily water-table fluctuations of 10 mm, and stable-isotopic measurements of plant water, indicated groundwater uptake rates of 200-300 mm/yr. Regional scaling suggests that groundwater evapotranspiration reaches 18-42 mm/yr across the landscape, accounting for 7 17% of the Mendoza River flow regionally. Our study highlights the reliance of ecosystem productivity in natural oases on Andean snowmelt, which is increasingly being diverted to one of the largest irrigated regions of the continent. Understanding the ecohydrological coupling of mountain and desert ecosystems here and elsewhere should help managers balance production agriculture and conservation of unique woodland ecosystems and the rural communities that rely on them.

    View details for Web of Science ID 000290661300004

    View details for PubMedID 21639036

  • Increases in the flux of carbon belowground stimulate nitrogen uptake and sustain the long-term enhancement of forest productivity under elevated CO2 ECOLOGY LETTERS Drake, J. E., Gallet-Budynek, A., Hofmockel, K. S., Bernhardt, E. S., Billings, S. A., Jackson, R. B., Johnsen, K. S., Lichter, J., McCarthy, H. R., McCormack, M. L., Moore, D. J., Oren, R., Palmroth, S., Phillips, R. P., Pippen, J. S., Pritchard, S. G., Treseder, K. K., Schlesinger, W. H., DeLucia, E. H., Finzi, A. C. 2011; 14 (4): 349-357


    The earth's future climate state is highly dependent upon changes in terrestrial C storage in response to rising concentrations of atmospheric CO₂. Here we show that consistently enhanced rates of net primary production (NPP) are sustained by a C-cascade through the root-microbe-soil system; increases in the flux of C belowground under elevated CO₂ stimulated microbial activity, accelerated the rate of soil organic matter decomposition and stimulated tree uptake of N bound to this SOM. This process set into motion a positive feedback maintaining greater C gain under elevated CO₂ as a result of increases in canopy N content and higher photosynthetic N-use efficiency. The ecosystem-level consequence of the enhanced requirement for N and the exchange of plant C for N belowground is the dominance of C storage in tree biomass but the preclusion of a large C sink in the soil.

    View details for DOI 10.1111/j.1461-0248.2011.01593.x

    View details for Web of Science ID 000288211000004

    View details for PubMedID 21303437

  • Increasing Forest Carbon Sequestration through Cooperation and Shared Strategies between China and the United States ENVIRONMENTAL SCIENCE & TECHNOLOGY Shao, G., Dai, L., Dukes, J. S., Jackson, R. B., Tang, L., Zhao, J. 2011; 45 (6): 2033-2034

    View details for DOI 10.1021/es200147k

    View details for Web of Science ID 000288146200001

    View details for PubMedID 21309612

  • Research frontiers in the analysis of coupled biogeochemical cycles FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Finzi, A. C., Cole, J. J., Doney, S. C., Holland, E. A., Jackson, R. B. 2011; 9 (1): 74-80

    View details for DOI 10.1890/100137

    View details for Web of Science ID 000286845400011

  • Opportunities and barriers to pumped-hydro energy storage in the United States RENEWABLE & SUSTAINABLE ENERGY REVIEWS Yang, C., Jackson, R. B. 2011; 15 (1): 839-844
  • Earth stewardship: a strategy for social–ecological transformation to reverse planetary degradation Journal of Environmental Studies and Sciences Chapin III, F. S., Pickett, S. T., Power, M. E., Jackson, R. B., Carter, D. M., Duke, C. 2011; 1: 44-53
  • A U.S. Carbon Cycle Science Plan U.S. Carbon Cycle Science Program, Washington, DC Michalak, A. M., Jackson, R. B., Marland, G., Sabine, C. L. 2011
  • Potential Impacts of Leakage from Deep CO2 Geosequestration on Overlying Freshwater Aquifers ENVIRONMENTAL SCIENCE & TECHNOLOGY Little, M. G., Jackson, R. B. 2010; 44 (23): 9225-9232


    Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

    View details for DOI 10.1021/es102235w

    View details for Web of Science ID 000284523400070

    View details for PubMedID 20977267

  • Water uptake and hydraulic redistribution across large woody root systems to 20 m depth PLANT CELL AND ENVIRONMENT Bleby, T. M., McElrone, A. J., Jackson, R. B. 2010; 33 (12): 2132-2148


    Deep water uptake and hydraulic redistribution (HR) are important processes in many forests, savannas and shrublands. We investigated HR in a semi-arid woodland above a unique cave system in central Texas to understand how deep root systems facilitate HR. Sap flow was measured in 9 trunks, 47 shallow roots and 12 deep roots of Quercus, Bumelia and Prosopis trees over 12 months. HR was extensive and continuous, involving every tree and 83% of roots, with the total daily volume of HR over a 1 month period estimated to be approximately 22% of daily transpiration. During drought, deep roots at 20 m depth redistributed water to shallow roots (hydraulic lift), while after rain, shallow roots at 0-0.5 m depth redistributed water among other shallow roots (lateral HR). The main driver of HR appeared to be patchy, dry soil near the surface, although water may also have been redistributed to mid-level depths via deeper lateral roots. Deep roots contributed up to five times more water to transpiration and HR than shallow roots during drought but dramatically reduced their contribution after rain. Our results suggest that deep-rooted plants are important drivers of water cycling in dry ecosystems and that HR can significantly influence landscape hydrology.

    View details for DOI 10.1111/j.1365-3040.2010.02212.x

    View details for Web of Science ID 000284166500011

    View details for PubMedID 20716068

  • Estimation of long-term basin scale evapotranspiration from streamflow time series WATER RESOURCES RESEARCH Palmroth, S., Katul, G. G., Hui, D., Mccarthy, H. R., Jackson, R. B., Oren, R. 2010; 46
  • Opportunities and Constraints for Forest Climate Mitigation BIOSCIENCE Jackson, R. B., Baker, J. S. 2010; 60 (9): 698-707
  • Interactions of the carbon cycle, human activity, and the climate system: a research portfolio CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY Canadell, J. G., Ciais, P., Dhakal, S., Dolman, H., Friedlingstein, P., Gurney, K. R., Held, A., Jackson, R. B., Le Quere, C., Malone, E. L., Ojima, D. S., Patwardhan, A., Peters, G. P., Raupach, M. R. 2010; 2 (4): 301-311
  • Amino acid abundance and proteolytic potential in North American soils OECOLOGIA Hofmockel, K. S., Fierer, N., Colman, B. P., Jackson, R. B. 2010; 163 (4): 1069-1078


    Studies of nitrogen (N) cycling have traditionally focused on N mineralization as the primary process limiting plant assimilation of N. Recent evidence has shown that plants may assimilate amino acids (AAs) directly, circumventing the mineralization pathway. However, the general abundance of soil AAs and their relative importance in plant N uptake remains unclear in most ecosystems. We compared the concentrations and potential production rates of AAs and NH(4) (+), as well as the edaphic factors that influence AA dynamics, in 84 soils across the United States. Across all sites, NH(4) (+) and AA-N comprised similar proportions of the total bioavailable N pool (approximately 20%), with NO(3) (-) being the dominant form of extractable N everywhere but in tundra and boreal forest soils. Potential rates of AA production were at least comparable to those of NH(4) (+) production in all ecosystems, particularly in semi-arid grasslands, where AA production rates were six times greater than for NH(4) (+) (P < 0.01). Potential rates of proteolytic enzyme activity were greatest in bacteria-dominated soils with low NH(4) (+) concentrations, including many grassland soils. Based on research performed under standardized laboratory conditions, our continental-scale analyses suggest that soil AA and NH(4) (+) concentrations are similar in most soils and that AAs may contribute to plant and microbial N demand in most ecosystems, particularly in ecosystems with N-poor soils.

    View details for DOI 10.1007/s00442-010-1601-9

    View details for Web of Science ID 000280083300023

    View details for PubMedID 20349250

  • Pursuing Geoengineering for Atmospheric Restoration ISSUES IN SCIENCE AND TECHNOLOGY Jackson, R. B., Salzman, J. 2010; 26 (4): 67-76
  • Greater seed production in elevated CO2 is not accompanied by reduced seed quality in Pinus taeda L. GLOBAL CHANGE BIOLOGY Way, D. A., LaDeau, S. L., McCarthy, H. R., Clark, J. S., Oren, R., Finzi, A. C., Jackson, R. B. 2010; 16 (3): 1046-1056
  • Stoichiometric controls on carbon, nitrogen, and phosphorus dynamics in decomposing litter ECOLOGICAL MONOGRAPHS Manzoni, S., Trofymow, J. A., Jackson, R. B., Porporato, A. 2010; 80 (1): 89-106
  • Re-assessment of plant carbon dynamics at the Duke free-air CO2 enrichment site: interactions of atmospheric [CO2] with nitrogen and water availability over stand development NEW PHYTOLOGIST Mccarthy, H. R., Oren, R., Johnsen, K. H., Gallet-Budynek, A., Pritchard, S. G., Cook, C. W., LaDeau, S. L., Jackson, R. B., Finzi, A. C. 2010; 185 (2): 514-528


    *The potential for elevated [CO(2)]-induced changes to plant carbon (C) storage, through modifications in plant production and allocation of C among plant pools, is an important source of uncertainty when predicting future forest function. Utilizing 10 yr of data from the Duke free-air CO(2) enrichment site, we evaluated the dynamics and distribution of plant C. *Discrepancy between heights measured for this study and previously calculated heights required revision of earlier allometrically based biomass determinations, resulting in higher (up to 50%) estimates of standing biomass and net primary productivity than previous assessments. *Generally, elevated [CO(2)] caused sustained increases in plant biomass production and in standing C, but did not affect the partitioning of C among plant biomass pools. Spatial variation in net primary productivity and its [CO(2)]-induced enhancement was controlled primarily by N availability, with the difference between precipitation and potential evapotranspiration explaining most interannual variability. Consequently, [CO(2)]-induced net primary productivity enhancement ranged from 22 to 30% in different plots and years. *Through quantifying the effects of nutrient and water availability on the forest productivity response to elevated [CO(2)], we show that net primary productivity enhancement by elevated [CO(2)] is not uniform, but rather highly dependent on the availability of other growth resources.

    View details for DOI 10.1111/j.1469-8137.2009.03078.x

    View details for Web of Science ID 000272893800016

    View details for PubMedID 19895671

  • Root responses along a subambient to elevated CO2 gradient in a C-3-C-4 grassland GLOBAL CHANGE BIOLOGY Anderson, L. J., Derner, J. D., Polley, H. W., Gordon, W. S., Eissenstat, D. M., Jackson, R. B. 2010; 16 (1): 454-468
  • Weekend Mischief Jackson, R. Wordsong, Boyds Mills Press. 2010
  • Hydraulic lift and tolerance to salinity of semiarid species: consequences for species interactions OECOLOGIA Armas, C., Padilla, F. M., Pugnaire, F. I., Jackson, R. B. 2010; 162 (1): 11-21


    The different abilities of plant species to use ephemeral or permanent water sources strongly affect physiological performance and species coexistence in water-limited ecosystems. In addition to withstanding drought, plants in coastal habitats often have to withstand highly saline soils, an additional ecological stress. Here we tested whether observed competitive abilities and C-water relations of two interacting shrub species from an arid coastal system were more related to differences in root architecture or salinity tolerance. We explored water sources of interacting Juniperus phoenicea Guss. and Pistacia lentiscus L. plants by conducting physiology measurements, including water relations, CO2 exchange, photochemical efficiency, sap osmolality, and water and C isotopes. We also conducted parallel soil analyses that included electrical conductivity, humidity, and water isotopes. During drought, Pistacia shrubs relied primarily on permanent salty groundwater, while isolated Juniperus plants took up the scarce and relatively fresh water stored in upper soil layers. As drought progressed further, the physiological activity of Juniperus plants nearly stopped while Pistacia plants were only slightly affected. Juniperus plants growing with Pistacia had stem-water isotopes that matched Pistacia, unlike values for isolated Juniperus plants. This result suggests that Pistacia shrubs supplied water to nearby Juniperus plants through hydraulic lift. This lifted water, however, did not appear to benefit Juniperus plants, as their physiological performance with co-occurring Pistacia plants was poor, including lower water potentials and rates of photosynthesis than isolated plants. Juniperus was more salt sensitive than Pistacia, which withstood salinity levels similar to that of groundwater. Overall, the different abilities of the two species to use salty water appear to drive the outcome of their interaction, resulting in asymmetric competition where Juniperus is negatively affected by Pistacia. Salt also seems to mediate the interaction between the two species, negating the potential positive effects of an additional water source via hydraulic lift.

    View details for DOI 10.1007/s00442-009-1447-1

    View details for Web of Science ID 000271736100002

    View details for PubMedID 19730891

  • Increased belowground biomass and soil CO2 fluxes after a decade of carbon dioxide enrichment in a warm-temperate forest ECOLOGY Jackson, R. B., Cook, C. W., Pippen, J. S., Palmer, S. M. 2009; 90 (12): 3352-3366


    Atmospheric CO2 concentrations have risen 40% since the start of the industrial revolution. Beginning in 1996, the Duke Free-Air CO2 Enrichment experiment has exposed plots in a loblolly pine forest to an additional 200 microL/L CO2 compared to trees growing in ambient CO2. This paper presents new belowground data and a synthesis of results through 2008, including root biomass and nutrient concentrations, soil respiration rates, soil pore-space CO2 concentrations, and soil-solution chemistry to 2 m depth. On average in elevated CO2, fine-root biomass in the top 15 cm of soil increased by 24%, or 59 g/m2 (26 g/m2 C). Coarse-root biomass sampled in 2008 was twice as great in elevated CO2 and suggests a storage of approximately 20 g C x m(-2) x yr(-1). Root C and N concentrations were unchanged, suggesting greater belowground plant demand for N in high CO2. Soil respiration was significantly higher by 23% on average as assessed by instantaneous infrared gas analysis and 24-h integrated estimates. N fertilization decreased soil respiration and fine-root biomass by approximately 10-20% in both ambient and elevated CO2. In recent years, increases in root biomass and soil respiration grew stronger, averaging approximately 30% at high CO2. Peak changes for root biomass, soil respiration, and other variables typically occurred in midsummer and diminished in winter. Soil CO2 concentrations between 15 and 100 cm depths increased 36-60% in elevated CO2. Differences from 30 cm depth and below were still increasing after 10 years' exposure to elevated CO2, with soil CO2 concentrations >10000 microL/L higher at 70- and 100-cm depths, potentially influencing soil acidity and rates of weathering. Soil solution Ca2+ and total base cation concentrations were 140% and 176% greater, respectively, in elevated CO2 at 200 cm depth. Similar increases were observed for soil-solution conductivity and alkalinity at 200 cm in elevated CO2. Overall, the effect of elevated CO2 belowground shows no sign of diminishing after more than a decade of CO2 enrichment.

    View details for Web of Science ID 000272700800008

    View details for PubMedID 20120805

  • A global meta-analysis of soil exchangeable cations, pH, carbon, and nitrogen with afforestation ECOLOGICAL APPLICATIONS Berthrong, S. T., Jobbagy, E. G., Jackson, R. B. 2009; 19 (8): 2228-2241


    Afforestation, the conversion of non-forested lands to forest plantations, can sequester atmospheric carbon dioxide, but the rapid growth and harvesting of biomass may deplete nutrients and degrade soils if managed improperly. The goal of this study is to evaluate how afforestation affects mineral soil quality, including pH, sodium, exchangeable cations, organic carbon, and nitrogen, and to examine the magnitude of these changes regionally where afforestation rates are high. We also examine potential mechanisms to reduce the impacts of afforestation on soils and to maintain long-term productivity. Across diverse plantation types (153 sites) to a depth of 30 cm of mineral soil, we observed significant decreases in nutrient cations (Ca, K, Mg), increases in sodium (Na), or both with afforestation. Across the data set, afforestation reduced soil concentrations of the macronutrient Ca by 29% on average (P < 0.05). Afforestation by Pinus alone decreased soil K by 23% (P < 0.05). Overall, plantations of all genera also led to a mean 71% increase of soil Na (P < 0.05). Mean pH decreased 0.3 units (P < 0.05) with afforestation. Afforestation caused a 6.7% and 15% (P < 0.05) decrease in soil C and N content respectively, though the effect was driven principally by Pinus plantations (15% and 20% decrease, P < 0.05). Carbon to nitrogen ratios in soils under plantations were 5.7-11.6% higher (P < 0.05). In several regions with high rates of afforestation, cumulative losses of N, Ca, and Mg are likely in the range of tens of millions of metric tons. The decreases indicate that trees take up considerable amounts of nutrients from soils; harvesting this biomass repeatedly could impair long-term soil fertility and productivity in some locations. Based on this study and a review of other literature, we suggest that proper site preparation and sustainable harvest practices, such as avoiding the removal or burning of harvest residue, could minimize the impact of afforestation on soils. These sustainable practices would in turn slow soil compaction, erosion, and organic matter loss, maintaining soil fertility to the greatest extent possible.

    View details for Web of Science ID 000271874300020

    View details for PubMedID 20014590

  • CO2 emissions from forest loss (vol 2, pg 737, 2009) NATURE GEOSCIENCE van der Werf, G. R., MORTON, D. C., DeFries, R. S., Olivier, J. G., Kasibhatla, P. S., Jackson, R. B., Collatz, G. J., Randerson, J. T. 2009; 2 (12): 829-829

    View details for DOI 10.1038/ngeo720

    View details for Web of Science ID 000272239400013

  • Future land use and land cover influences on regional biogenic emissions and air quality in the United States ATMOSPHERIC ENVIRONMENT Chen, J., Avise, J., Guenther, A., Wiedinmyer, C., Salathe, E., Jackson, R. B., Lamb, B. 2009; 43 (36): 5771-5780
  • CO2 emissions from forest loss NATURE GEOSCIENCE van der Werf, G. R., MORTON, D. C., DeFries, R. S., Olivier, J. G., Kasibhatla, P. S., Jackson, R. B., Collatz, G. J., Randerson, J. T. 2009; 2 (11): 737-738

    View details for DOI 10.1038/ngeo671

    View details for Web of Science ID 000271388500004

  • Afforestation Alters the Composition of Functional Genes in Soil and Biogeochemical Processes in South American Grasslands APPLIED AND ENVIRONMENTAL MICROBIOLOGY Berthrong, S. T., Schadt, C. W., Pineiro, G., Jackson, R. B. 2009; 75 (19): 6240-6248


    Soil microbes are highly diverse and control most soil biogeochemical reactions. We examined how microbial functional genes and biogeochemical pools responded to the altered chemical inputs accompanying land use change. We examined paired native grasslands and adjacent Eucalyptus plantations (previously grassland) in Uruguay, a region that lacked forests before European settlement. Along with measurements of soil carbon, nitrogen, and bacterial diversity, we analyzed functional genes using the GeoChip 2.0 microarray, which simultaneously quantified several thousand genes involved in soil carbon and nitrogen cycling. Plantations and grassland differed significantly in functional gene profiles, bacterial diversity, and biogeochemical pool sizes. Most grassland profiles were similar, but plantation profiles generally differed from those of grasslands due to differences in functional gene abundance across diverse taxa. Eucalypts decreased ammonification and N fixation functional genes by 11% and 7.9% (P < 0.01), which correlated with decreased microbial biomass N and more NH(4)(+) in plantation soils. Chitinase abundance decreased 7.8% in plantations compared to levels in grassland (P = 0.017), and C polymer-degrading genes decreased by 1.5% overall (P < 0.05), which likely contributed to 54% (P < 0.05) more C in undecomposed extractable soil pools and 27% less microbial C (P < 0.01) in plantation soils. In general, afforestation altered the abundance of many microbial functional genes, corresponding with changes in soil biogeochemistry, in part through altered abundance of overall functional gene types rather than simply through changes in specific taxa. Such changes in microbial functional genes correspond with altered C and N storage and have implications for long-term productivity in these soils.

    View details for DOI 10.1128/AEM.01126-09

    View details for Web of Science ID 000270113200024

    View details for PubMedID 19700539

    View details for PubMedCentralID PMC2753075

  • Ecohydrology in a human-dominated landscape ECOHYDROLOGY Jackson, R. B., Jobbagy, E. G., Nosetto, M. D. 2009; 2 (3): 383-389

    View details for DOI 10.1002/eco.81

    View details for Web of Science ID 000271491500018

  • Reciprocal influence of crops and shallow ground water in sandy landscapes of the Inland Pampas FIELD CROPS RESEARCH Nosetto, M. D., Jobbagy, E. G., Jackson, R. B., Sznaider, G. A. 2009; 113 (2): 138-148
  • Primary Productivity and Water Balance of Grassland Vegetation on Three Soils in a Continuous CO2 Gradient: Initial Results from the Lysimeter CO2 Gradient Experiment ECOSYSTEMS Fay, P. A., Kelley, A. M., Procter, A. C., Hui, D., Jin, V. L., Jackson, R. B., Johnson, H. B., Polley, H. W. 2009; 12 (5): 699-714
  • Sheep Grazing Decreases Organic Carbon and Nitrogen Pools in the Patagonian Steppe: Combination of Direct and Indirect Effects ECOSYSTEMS Golluscio, R. A., Austin, A. T., Garcia Martinez, G. C., Gonzalez-Polo, M., Sala, O. E., Jackson, R. B. 2009; 12 (4): 686-697
  • Risks to forest carbon offset projects in a changing climate FOREST ECOLOGY AND MANAGEMENT Galik, C. S., Jackson, R. B. 2009; 257 (11): 2209-2216
  • Leaf isoprene emission rate as a function of atmospheric CO2 concentration GLOBAL CHANGE BIOLOGY Wilkinson, M. J., Monson, R. K., Trahan, N., Lee, S., Brown, E., Jackson, R. B., Polley, H. W., Fay, P. A., Fall, R. 2009; 15 (5): 1189-1200
  • Grazing effects on belowground C and N stocks along a network of cattle exclosures in temperate and subtropical grasslands of South America GLOBAL BIOGEOCHEMICAL CYCLES Pineiro, G., Paruelo, J. M., Jobbagy, E. G., Jackson, R. B., Oesterheld, M. 2009; 23
  • Physical and Economic Potential of Geological CO2 Storage in Saline Aquifers ENVIRONMENTAL SCIENCE & TECHNOLOGY Eccles, J. K., Pratson, L., Newell, R. G., Jackson, R. B. 2009; 43 (6): 1962-1969


    Carbon sequestration in sandstone saline reservoirs holds great potential for mitigating climate change, but its storage potential and cost per ton of avoided CO2 emissions are uncertain. We develop a general model to determine the maximum theoretical constraints on both storage potential and injection rate and use it to characterize the economic viability of geosequestration in sandstone saline aquifers. When applied to a representative set of aquifer characteristics, the model yields results that compare favorably with pilot projects currently underway. Over a range of reservoir properties, maximum effective storage peaks at an optimal depth of 1600 m, at which point 0.18-0.31 metric tons can be stored per cubic meter of bulk volume of reservoir. Maximum modeled injection rates predict minima for storage costs in a typical basin in the range of $2-7/ ton CO2 (2005 U.S.$) depending on depth and basin characteristics in our base-case scenario. Because the properties of natural reservoirs in the United States vary substantially, storage costs could in some cases be lower or higher by orders of magnitude. We conclude that available geosequestration capacity exhibits a wide range of technological and economic attractiveness. Like traditional projects in the extractive industries, geosequestration capacity should be exploited starting with the low-cost storage options first then moving gradually up the supply curve.

    View details for DOI 10.1021/es801572e

    View details for Web of Science ID 000264108800050

    View details for PubMedID 19368199

  • Set-asides can be better climate investment than corn ethanol ECOLOGICAL APPLICATIONS Pineiro, G., Jobbagy, E. G., Baker, J., Murray, B. C., Jackson, R. B. 2009; 19 (2): 277-282


    Although various studies have shown that corn ethanol reduces greenhouse gas (GHG) emissions by displacing fossil fuel use, many of these studies fail to include how land-use history affects the net carbon balance through changes in soil carbon content. We evaluated the effectiveness and economic value of corn and cellulosic ethanol production for reducing net GHG emissions when produced on lands with different land-use histories, comparing these strategies with reductions achieved by set-aside programs such as the Conservation Reserve Program (CRP). Depending on prior land use, our analysis shows that C releases from the soil after planting corn for ethanol may in some cases completely offset C gains attributed to biofuel generation for at least 50 years. More surprisingly, based on our comprehensive analysis of 142 soil studies, soil C sequestered by setting aside former agricultural land was greater than the C credits generated by planting corn for ethanol on the same land for 40 years and had equal or greater economic net present value. Once commercially available, cellulosic ethanol produced in set-aside grasslands should provide the most efficient tool for GHG reduction of any scenario we examined. Our results suggest that conversion of CRP lands or other set-aside programs to corn ethanol production should not be encouraged through greenhouse gas policies.

    View details for Web of Science ID 000263719400001

    View details for PubMedID 19323189

  • Assessing interactive responses in litter decomposition in mixed species litter PLANT AND SOIL Hui, D., Jackson, R. B. 2009; 314 (1-2): 263-271
  • Soil carbon sequestration in a pine forest after 9 years of atmospheric CO2 enrichment GLOBAL CHANGE BIOLOGY Lichter, J., Billings, S. A., Ziegler, S. E., Gaindh, D., Ryals, R., Finzi, A. C., Jackson, R. B., Stemmler, E. A., Schlesinger, W. H. 2008; 14 (12): 2910-2922
  • Fine-root respiration in a loblolly pine (Pinus taeda L.) forest exposed to elevated CO2 and N fertilization PLANT CELL AND ENVIRONMENT Drake, J. E., Stoy, P. C., Jackson, R. B., DeLucia, E. H. 2008; 31 (11): 1663-1672


    Forest ecosystems release large amounts of carbon to the atmosphere from fine-root respiration (R(r)), but the control of this flux and its temperature sensitivity (Q(10)) are poorly understood. We attempted to: (1) identify the factors limiting this flux using additions of glucose and an electron transport uncoupler (carbonyl cyanide m-chlorophenylhydrazone); and (2) improve yearly estimates of R(r) by directly measuring its Q(10)in situ using temperature-controlled cuvettes buried around intact, attached roots. The proximal limits of R(r) of loblolly pine (Pinus taeda L.) trees exposed to free-air CO(2) enrichment (FACE) and N fertilization were seasonally variable; enzyme capacity limited R(r) in the winter, and a combination of substrate supply and adenylate availability limited R(r) in summer months. The limiting factors of R(r) were not affected by elevated CO(2) or N fertilization. Elevated CO(2 )increased annual stand-level R(r) by 34% whereas the combination of elevated CO(2) and N fertilization reduced R(r) by 40%. Measurements of in situ R(r) with high temporal resolution detected diel patterns that were correlated with canopy photosynthesis with a lag of 1 d or less as measured by eddy covariance, indicating a dynamic link between canopy photosynthesis and root respiration. These results suggest that R(r) is coupled to daily canopy photosynthesis and increases with carbon allocation below ground.

    View details for DOI 10.1111/j.1365-3040.2008.01869.x

    View details for Web of Science ID 000259817700012

    View details for PubMedID 18684240

  • Protecting climate with forests ENVIRONMENTAL RESEARCH LETTERS Jackson, R. B., Randerson, J. T., Canadell, J. G., Anderson, R. G., Avissar, R., Baldocchi, D. D., Bonan, G. B., Caldeira, K., Diffenbaugh, N. S., Field, C. B., Hungate, B. A., Jobbagy, E. G., Kueppers, L. M., Nosetto, M. D., Pataki, D. E. 2008; 3 (4)
  • Stream acidification and base cation losses with grassland afforestation WATER RESOURCES RESEARCH Farley, K. A., Pineiro, G., Palmer, S. M., Jobbagy, E. G., Jackson, R. B. 2008; 44
  • The global stoichiometry of litter nitrogen mineralization SCIENCE Manzoni, S., Jackson, R. B., Trofymow, J. A., Porporato, A. 2008; 321 (5889): 684-686


    Plant residue decomposition and the nutrient release to the soil play a major role in global carbon and nutrient cycling. Although decomposition rates vary strongly with climate, nitrogen immobilization into litter and its release in mineral forms are mainly controlled by the initial chemical composition of the residues. We used a data set of approximately 2800 observations to show that these global nitrogen-release patterns can be explained by fundamental stoichiometric relationships of decomposer activity. We show how litter quality controls the transition from nitrogen accumulation into the litter to release and alters decomposers' respiration patterns. Our results suggest that decomposers lower their carbon-use efficiency to exploit residues with low initial nitrogen concentration, a strategy used broadly by bacteria and consumers across trophic levels.

    View details for DOI 10.1126/science.1159792

    View details for Web of Science ID 000258077700042

    View details for PubMedID 18669860

  • Regional patterns and controls of ecosystem salinization with grassland afforestation along a rainfall gradient GLOBAL BIOGEOCHEMICAL CYCLES Nosetto, M. D., Jobbagy, E. G., Toth, T., Jackson, R. B. 2008; 22 (2)
  • Nonlinear root-derived carbon sequestration across a gradient of nitrogen and phosphorous deposition in experimental mesocosms GLOBAL CHANGE BIOLOGY Bradford, M. A., Fierer, N., Jackson, R. B., Maddox, T. R., Reynolds, J. F. 2008; 14 (5): 1113-1124
  • Measuring uncertainty in estimates of biodiversity loss: The example of biodiversity intactness variance BIOLOGICAL CONSERVATION Hui, D., Biggs, R., Scholes, R. J., Jackson, R. B. 2008; 141 (4): 1091-1094
  • Hydraulic traits are influenced by phylogenetic history in the drought-resistant, invasive genus Juniperus (Cupressaceae) American Journal of Botany Willson, C. J., Manos, P. S., Jackson, R. B. 2008; 95: 299-314
  • Fine root dynamics in a loblolly pine forest are influenced by free-air-CO2-enrichment: a six-year-minirhizotron study Global Change Biology Pritchard, S. G., Strand, A. E., McCormack, M. L., Davis, M. A., Finzi, A. C., Jackson, R. B., Matamala, R., Rogers, H. H., Oren, R. 2008; 14: 588-602
  • Uncertainty in allometric exponent estimation: A case study in scaling metabolic rate with body mass JOURNAL OF THEORETICAL BIOLOGY Hui, D., Jackson, R. B. 2007; 249 (1): 168-177


    Many factors could influence the allometric scaling exponent beta estimation, but have not been explored systematically. We investigated the influences of three factors on the estimate of beta based on a data set of 626 species of basal metabolic rate and mass in mammals. The influence of sampling error was tested by re-sampling with different sample sizes using a Monte Carlo method. Small random errors were introduced to measured data to examine their influence on parameter estimations. The influence of analysis method was also evaluated by applying nonlinear and linear regressions to the original data. Results showed that a relative large sample size was required to lower statistical inference errors. When sample size n was 10% of the base population size (n=63), 35% of the samples supported beta=2/3, 39% supported beta=3/4, and 15% rejected beta=0.711, even though the base population had a beta=0.711. The controversy surrounding the estimation of beta in the literature could be partially attributable to such small sample sizes in many studies. Measurement errors in body mass and base metabolic rate, especially in body mass, could largely increase alpha and beta errors. Analysis methods also affected parameter estimations. Nonlinear regressions provided better estimates of the scaling exponent that were significantly higher than these commonly estimated by linear regressions. This study demonstrated the importance of the quantity and quality of data as well as analysis method in power law analysis, raising caution in interpreting power law results. Meta-data synthesis using data from independent studies seems to be a proper approach in the future, but caution should be taken to make sure that such measurements are made using similar protocols.

    View details for DOI 10.1016/j.jtbi.2007.07.003

    View details for Web of Science ID 000250847700015

    View details for PubMedID 17720203

  • Metagenomic and small-subunit rRNA analyses reveal the genetic diversity of bacteria, archaea, fungi, and viruses in soil APPLIED AND ENVIRONMENTAL MICROBIOLOGY Fierer, N., Breitbart, M., Nulton, J., Salamon, P., Lozupone, C., Jones, R., Robeson, M., Edwards, R. A., Felts, B., Rayhawk, S., Knight, R., Rohwer, F., Jackson, R. B. 2007; 73 (21): 7059-7066


    Recent studies have highlighted the surprising richness of soil bacterial communities; however, bacteria are not the only microorganisms found in soil. To our knowledge, no study has compared the diversities of the four major microbial taxa, i.e., bacteria, archaea, fungi, and viruses, from an individual soil sample. We used metagenomic and small-subunit RNA-based sequence analysis techniques to compare the estimated richness and evenness of these groups in prairie, desert, and rainforest soils. By grouping sequences at the 97% sequence similarity level (an operational taxonomic unit [OTU]), we found that the archaeal and fungal communities were consistently less even than the bacterial communities. Although total richness levels are difficult to estimate with a high degree of certainty, the estimated number of unique archaeal or fungal OTUs appears to rival or exceed the number of unique bacterial OTUs in each of the collected soils. In this first study to comprehensively survey viral communities using a metagenomic approach, we found that soil viruses are taxonomically diverse and distinct from the communities of viruses found in other environments that have been surveyed using a similar approach. Within each of the four microbial groups, we observed minimal taxonomic overlap between sites, suggesting that soil archaea, bacteria, fungi, and viruses are globally as well as locally diverse.

    View details for DOI 10.1128/AEM.00358-07

    View details for Web of Science ID 000250700600042

    View details for PubMedID 17827313

    View details for PubMedCentralID PMC2074941

  • Aquaporin-mediated changes in hydraulic conductivity of deep tree roots accessed via caves PLANT CELL AND ENVIRONMENT McElrone, A. J., Bichler, J., Pockman, W. T., Addington, R. N., Linder, C. R., Jackson, R. B. 2007; 30 (11): 1411-1421


    Although deep roots can contribute substantially to whole-tree water use, little is known about deep root functioning because of limited access for in situ measurements. We used a cave system on the Edwards Plateau of central Texas to investigate the physiology of water transport in roots at 18-20 m depth for two common tree species, Quercus fusiformis and Bumelia lanuginosa. Using sap flow and water potential measurements on deep roots, we found that calculated root hydraulic conductivity (RHC) fluctuated diurnally for both species and decreased under shading for B. lanuginosa. To assess whether these dynamic changes in RHC were regulated during initial water absorption by fine roots, we used an ultra-low flowmeter and hydroxyl radical inhibition to measure in situ fine root hydraulic conductivity (FRHC) and aquaporin contribution to FRHC (AQPC), respectively. During the summer, FRHC and AQPC were found to cycle diurnally in both species, with peaks corresponding to the period of highest transpirational demand at midday. During whole-tree shade treatments, B. lanuginosa FRHC ceased diurnal cycling and decreased by 75 and 35% at midday and midnight, respectively, while AQPC decreased by 41 and 30% during both time periods. A controlled growth-chamber study using hydroponically grown saplings confirmed daily cycling and shade-induced reductions in FRHC and AQPC. Winter measurements showed that the evergreen Q. fusiformis maintained high FRHC and AQPC throughout the year, while the deciduous B. lanuginosa ceased diurnal cycling and exhibited its lowest annual values for both parameters in winter. Adjustments in FRHC and AQPC to changing canopy water demands may help the trees maintain the use of reliable water resources from depth and contribute to the success of these species in this semi-arid environment.

    View details for DOI 10.1111/j.1365-3040.2007.01714.x

    View details for Web of Science ID 000249826400006

    View details for PubMedID 17897411

  • Environmental controls on the landscape-scale biogeography of stream bacterial communities ECOLOGY Fierer, N., Morse, J. L., Berthrong, S. T., Bernhardt, E. S., Jackson, R. B. 2007; 88 (9): 2162-2173


    We determined the biogeographical distributions of stream bacteria and the biogeochemical factors that best explained heterogeneity for 23 locations within the Hubbard Brook watershed, a 3000-ha forested watershed in New Hampshire, USA. Our goal was to assess the factor, or set of factors, responsible for generating the biogeographical patterns exhibited by microorganisms at the landscape scale. We used DNA fingerprinting to characterize bacteria inhabiting fine benthic organic matter (FBOM) because of their important influence on stream nutrient dynamics. Across the watershed, streams of similar pH had similar FBOM bacterial communities. Streamwater pH was the single variable most strongly correlated with the relative distance between communities (Spearman's p = 0.66, P < 0.001) although there were other contributing factors, including the quality of the fine benthic organic matter and the amount of dissolved organic carbon and nitrogen in the stream water (P < 0.05 for each). There was no evidence of an effect of geographic distance on bacterial community composition, suggesting that dispersal limitation has little influence on the observed biogeographical patterns in streams across this landscape. Cloning and sequencing of small-subunit rRNA genes confirmed the DNA fingerprinting results and revealed strong shifts among bacterial groups along the pH gradient. With an increase in streamwater pH, the abundance of acidobacteria in the FBOM bacterial community decreased (from 71% to 38%), and the abundance of proteobacteria increased (from 11% to 47%). Together these results suggest that microorganisms, like "macro"-organisms, do exhibit biogeographical patterns at the landscape scale and that these patterns may be predictable based on biogeochemical factors.

    View details for Web of Science ID 000249500900003

    View details for PubMedID 17918395

  • Effects of elevated atmospheric carbon dioxide on amino acid and NH4+-N cycling in a temperate pine ecosystem GLOBAL CHANGE BIOLOGY Hofmockel, K. S., Schlesinger, W. H., Jackson, R. B. 2007; 13 (9): 1950-1959
  • Increases in nitrogen uptake rather than nitrogen-use efficiency support higher rates of temperate forest productivity under elevated CO2 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Finzi, A. C., Norby, R. J., Calfapietra, C., Gallet-Budynek, A., Gielen, B., Holmes, W. E., Hoosbeek, M. R., Iversen, C. M., Jackson, R. B., Kubiske, M. E., Ledford, J., Liberloo, M., Oren, R., Polle, A., Pritchard, S., Zak, D. R., Schlesinger, W. H., Ceulemans, R. 2007; 104 (35): 14014-14019


    Forest ecosystems are important sinks for rising concentrations of atmospheric CO(2). In previous research, we showed that net primary production (NPP) increased by 23 +/- 2% when four experimental forests were grown under atmospheric concentrations of CO(2) predicted for the latter half of this century. Because nitrogen (N) availability commonly limits forest productivity, some combination of increased N uptake from the soil and more efficient use of the N already assimilated by trees is necessary to sustain the high rates of forest NPP under free-air CO(2) enrichment (FACE). In this study, experimental evidence demonstrates that the uptake of N increased under elevated CO(2) at the Rhinelander, Duke, and Oak Ridge National Laboratory FACE sites, yet fertilization studies at the Duke and Oak Ridge National Laboratory FACE sites showed that tree growth and forest NPP were strongly limited by N availability. By contrast, nitrogen-use efficiency increased under elevated CO(2) at the POP-EUROFACE site, where fertilization studies showed that N was not limiting to tree growth. Some combination of increasing fine root production, increased rates of soil organic matter decomposition, and increased allocation of carbon (C) to mycorrhizal fungi is likely to account for greater N uptake under elevated CO(2). Regardless of the specific mechanism, this analysis shows that the larger quantities of C entering the below-ground system under elevated CO(2) result in greater N uptake, even in N-limited ecosystems. Biogeochemical models must be reformulated to allow C transfers below ground that result in additional N uptake under elevated CO(2).

    View details for DOI 10.1073/pnas.0706518104

    View details for Web of Science ID 000249187500030

    View details for PubMedID 17709743

    View details for PubMedCentralID PMC1955801

  • New directions in microbial ecology ECOLOGY Jackson, R. B., Fierer, N., Schimel, J. P. 2007; 88 (6): 1343-1344
  • Toward an ecological classification of soil bacteria ECOLOGY Fierer, N., Bradford, M. A., Jackson, R. B. 2007; 88 (6): 1354-1364


    Although researchers have begun cataloging the incredible diversity of bacteria found in soil, we are largely unable to interpret this information in an ecological context, including which groups of bacteria are most abundant in different soils and why. With this study, we examined how the abundances of major soil bacterial phyla correspond to the biotic and abiotic characteristics of the soil environment to determine if they can be divided into ecologically meaningful categories. To do this, we collected 71 unique soil samples from a wide range of ecosystems across North America and looked for relationships between soil properties and the relative abundances of six dominant bacterial phyla (Acidobacteria, Bacteroidetes, Firmicutes, Actinobacteria, alpha-Proteobacteria, and the beta-Proteobacteria). Of the soil properties measured, net carbon (C) mineralization rate (an index of C availability) was the best predictor of phylum-level abundances. There was a negative correlation between Acidobacteria abundance and C mineralization rates (r2 = 0.26, P < 0.001), while the abundances of beta-Proteobacteria and Bacteroidetes were positively correlated with C mineralization rates (r2 = 0.35, P < 0.001 and r2 = 0.34, P < 0.001, respectively). These patterns were explored further using both experimental and meta-analytical approaches. We amended soil cores from a specific site with varying levels of sucrose over a 12-month period to maintain a gradient of elevated C availabilities. This experiment confirmed our survey results: there was a negative relationship between C amendment level and the abundance of Acidobacteria (r2 = 0.42, P < 0.01) and a positive relationship for both Bacteroidetes and beta-Proteobacteria (r2 = 0.38 and 0.70, respectively; P < 0.01 for each). Further support for a relationship between the relative abundances of these bacterial phyla and C availability was garnered from an analysis of published bacterial clone libraries from bulk and rhizosphere soils. Together our survey, experimental, and meta-analytical results suggest that certain bacterial phyla can be differentiated into copiotrophic and oligotrophic categories that correspond to the r- and K-selected categories used to describe the ecological attributes of plants and animals. By applying the copiotroph-oligotroph concept to soil microorganisms we can make specific predictions about the ecological attributes of various bacterial taxa and better understand the structure and function of soil bacterial communities.

    View details for Web of Science ID 000247203100003

    View details for PubMedID 17601128

  • Groundwater and soil chemical changes under phreatophytic tree plantations JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES Jobbagy, E. G., Jackson, R. B. 2007; 112 (G2)
  • Coupling diurnal cytosolic Ca2+ oscillations to the CAS-IP3 pathway in Arabidopsis SCIENCE Tang, R., Han, S., Zheng, H., Cook, C. W., Choi, C. S., Woerner, T. E., Jackson, R. B., Pei, Z. 2007; 315 (5817): 1423-1426


    Various signaling pathways rely on changes in cytosolic calcium ion concentration ([Ca2+]i). In plants, resting [Ca2+]i oscillates diurnally. We show that in Arabidopsis thaliana, [Ca2+]i oscillations are synchronized to extracellular Ca2+ concentration ([Ca2+]o) oscillations largely through the Ca2+-sensing receptor CAS. CAS regulates concentrations of inositol 1,4,5-trisphosphate (IP3), which in turn directs release of Ca2+ from internal stores. The oscillating amplitudes of [Ca2+]o and [Ca2+]i are controlled by soil Ca2+ concentrations and transpiration rates. The phase and period of oscillations are likely determined by stomatal conductance. Thus, the internal concentration of Ca2+ in plant cells is constantly being actively revised.

    View details for DOI 10.1126/science.1134457

    View details for Web of Science ID 000244752200037

    View details for PubMedID 17347443

  • Effects of elevated atmospheric CO2 on amino acid and NH4+-N cycling in a temperate pine ecosystem Global Change Biology Hofmockel, K. S., Schlesinger, W. H., Jackson, R. B. 2007; 13: 13:1950-1959
  • Carbon and water tradeoffs in conversions to forests and shrublands Terrestrial Ecosystems in a Changing World Jackson, R. B., Farley, K. A., Hoffmann, W. A., Jobbagy, E. G., McCulley, R. L. Springer. 2007: 237–246
  • Inhibition of nitrification alters carbon turnover in the Patagonian steppe ECOSYSTEMS Austin, A. T., Sala, O. E., Jackson, R. B. 2006; 9 (8): 1257-1265
  • Predicting the temperature dependence of microbial respiration in soil: A continental-scale analysis GLOBAL BIOGEOCHEMICAL CYCLES Fierer, N., Colman, B. P., Schimel, J. P., Jackson, R. B. 2006; 20 (3)
  • Determinants of biodiversity change: Ecological tools for building scenarios ECOLOGY Sala, O. E., Jackson, R. B. 2006; 87 (8): 1875-1876
  • Xylem cavitation caused by drought and freezing stress in four co-occurring Juniperus species PHYSIOLOGIA PLANTARUM Willson, C. J., Jackson, R. B. 2006; 127 (3): 374-382
  • Functional coordination between leaf gas exchange and vulnerability to xylem cavitation in temperate forest trees PLANT CELL AND ENVIRONMENT Maherali, H., Moura, C. F., Caldeira, M. C., Willson, C. J., Jackson, R. B. 2006; 29 (4): 571-583


    We examined functional coordination among stem and root vulnerability to xylem cavitation, plant water transport characteristics and leaf traits in 14 co-occurring temperate tree species. Relationships were evaluated using both traditional cross-species correlations and phylogenetically independent contrast (PIC) correlations. For stems, the xylem tension at which 50% of hydraulic conductivity was lost (psi50) was positively associated (P < 0.001) with specific conductivity (K(S)) and with mean hydraulically weighted xylem conduit diameter (D(h-w)), but was only marginally (P = 0.06) associated with leaf specific conductivity (K(L)). The PIC correlation for each of these relationships, however, was not statistically significant. There was also no relationship between root psi50 and root K(S) in either cross-species or PIC analysis. Photosynthetic rate (A) and stomatal conductance (g(s)) were strongly and positively correlated with root psi50 in the cross-species analysis (P < 0.001), a relationship that was robust to phylogenetic correction (P < 0.01). A and g(s) were also positively correlated with stem psi50 in the cross-species analysis (P = 0.02 and 0.10, respectively). However, only A was associated with stem psi50 in the PIC analysis (P = 0.04). Although the relationship between vulnerability to cavitation and xylem conductivity traits within specific organs (i.e. stems and roots) was weak, the strong correlation between g(s) and root psi50 across species suggests that there is a trade-off between vulnerability to cavitation and water transport capacity at the whole-plant level. Our results were therefore consistent with the expectation of coordination between vulnerability to xylem cavitation and the regulation of stomatal conductance, and highlight the potential physiological and evolutionary significance of root hydraulic properties in controlling interspecific variation in leaf function.

    View details for DOI 10.1111/j.1365-3040.2005.01433.x

    View details for Web of Science ID 000236385900010

    View details for PubMedID 17080608

  • The diversity and biogeography of soil bacterial communities PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Fierer, N., Jackson, R. B. 2006; 103 (3): 626-631


    For centuries, biologists have studied patterns of plant and animal diversity at continental scales. Until recently, similar studies were impossible for microorganisms, arguably the most diverse and abundant group of organisms on Earth. Here, we present a continental-scale description of soil bacterial communities and the environmental factors influencing their biodiversity. We collected 98 soil samples from across North and South America and used a ribosomal DNA-fingerprinting method to compare bacterial community composition and diversity quantitatively across sites. Bacterial diversity was unrelated to site temperature, latitude, and other variables that typically predict plant and animal diversity, and community composition was largely independent of geographic distance. The diversity and richness of soil bacterial communities differed by ecosystem type, and these differences could largely be explained by soil pH (r(2) = 0.70 and r(2) = 0.58, respectively; P < 0.0001 in both cases). Bacterial diversity was highest in neutral soils and lower in acidic soils, with soils from the Peruvian Amazon the most acidic and least diverse in our study. Our results suggest that microbial biogeography is controlled primarily by edaphic variables and differs fundamentally from the biogeography of "macro" organisms.

    View details for DOI 10.1073/pnas.0507535103

    View details for Web of Science ID 000234727800024

    View details for PubMedID 16407148

    View details for PubMedCentralID PMC1334650

  • Potential nitrogen constraints on soil carbon sequestration under low and elevated atmospheric CO2 ECOLOGY Gill, R. A., Anderson, L. J., Polley, H. W., Johnson, H. B., Jackson, R. B. 2006; 87 (1): 41-52


    The interaction between nitrogen cycling and carbon sequestration is critical in predicting the consequences of anthropogenic increases in atmospheric CO2 (hereafter, Ca). The progressive N limitation (PNL) theory predicts that carbon sequestration in plants and soils with rising Ca may be constrained by the availability of nitrogen in many ecosystems. Here we report on the interaction between C and N dynamics during a four-year field experiment in which an intact C3/C4 grassland was exposed to a gradient in Ca from 200 to 560 micromol/mol. There were strong species effects on decomposition dynamics, with C loss positively correlated and N mineralization negatively correlated with Ca for litter of the C3 forb Solanum dimidiatum, whereas decomposition of litter from the C4 grass Bothriochloa ischaemum was unresponsive to Ca. Both soil microbial biomass and soil respiration rates exhibited a nonlinear response to Ca, reaching a maximum at approximately 440 micromol/mol Ca. We found a general movement of N out of soil organic matter and into aboveground plant biomass with increased Ca. Within soils we found evidence of C loss from recalcitrant soil C fractions with narrow C:N ratios to more labile soil fractions with broader C:N ratios, potentially due to decreases in N availability. The observed reallocation of N from soil to plants over the last three years of the experiment supports the PNL theory that reductions in N availability with rising Ca could initially be overcome by a transfer of N from low C:N ratio fractions to those with higher C:N ratios. Although the transfer of N allowed plant production to increase with increasing Ca, there was no net soil C sequestration at elevated Ca, presumably because relatively stable C is being decomposed to meet microbial and plant N requirements. Ultimately, if the C gained by increased plant production is rapidly lost through decomposition, the shift in N from older soil organic matter to rapidly decomposing plant tissue may limit net C sequestration with increased plant production.

    View details for Web of Science ID 000236020000006

    View details for PubMedID 16634295

  • Geographical and interannual variability in biomass partitioning in grassland ecosystems: a synthesis of field data NEW PHYTOLOGIST Hui, D. F., Jackson, R. B. 2006; 169 (1): 85-93


    Biomass partitioning is an important variable in terrestrial ecosystem carbon modeling. However, geographical and interannual variability in f(BNPP), defined as the fraction of belowground net primary productivity (BNPP) to total NPP, and its relationship with climatic variables, have not been explored. Here we addressed these issues by synthesizing 94 site-year field biomass data at 12 grassland sites around the world from a global NPP database and from the literature. Results showed that f(BNPP) varied from 0.40 to 0.86 across 12 sites. In general, savanna and humid savanna ecosystems had smaller f(BNPP) but larger interannual variability in f(BNPP), and cold desert steppes had larger f(BNPP) but smaller interannual variability. While mean f(BNPP) at a site decreased significantly with increasing mean annual temperature and precipitation across sites, no consistent temporal response of f(BNPP) with annual temperature and precipitation was found within sites. Based on these results, both geographical variability in f(BNPP) and the divergent responses of f(BNPP) with climatic variables at geographical and temporal scales should be considered in global C modeling.

    View details for DOI 10.1111/j.1469-8137.2005.01569.x

    View details for Web of Science ID 000233530400010

    View details for PubMedID 16390421

  • Does nitrogen constrain carbon cycling, or does carbon input stimulate nitrogen cycling? ECOLOGY Luo, Y. Q., Field, C. B., Jackson, R. B. 2006; 87 (1): 3-4
  • Ecosystem changes associated with grazing in subhumid South American grasslands Journal of Vegetation Science Altesor, A., Piñeiro, G., Lezama, F., Jackson, R. B., Sarasola, M., Paruelo, J. M. 2006; 17: 323-332
  • Animal Mischief Jackson, R. Wordsong, Boyds Mills Press. 2006
  • Grassland afforestation: towards an integrative perspective of its ecological opportunities and costs Agrociencia Jobbágy, E. G., Vasallo, M., Farley, K. A., Piñeiro, G., Garbulsky, M. F., Nosetto, M. M., Jackson, R. B., Paruelo, J. M. 2006; 10: 109-124
  • Progressive nitrogen limitation of ecosystem processes under elevated CO2 in a warm-temperate forest ECOLOGY Finzi, A. C., Moore, D. J., DeLucia, E. H., Lichter, J., Hofmockel, K. S., Jackson, R. B., Kim, H. S., Matamala, R., McCarthy, H. R., Oren, R., Pippen, J. S., Schlesinger, W. H. 2006; 87 (1): 15-25


    A hypothesis for progressive nitrogen limitation (PNL) proposes that net primary production (NPP) will decline through time in ecosystems subjected to a step-function increase in atmospheric CO2. The primary mechanism driving this response is a rapid rate of N immobilization by plants and microbes under elevated CO2 that depletes soils of N, causing slower rates of N mineralization. Under this hypothesis, there is little long-term stimulation of NPP by elevated CO2 in the absence of exogenous inputs of N. We tested this hypothesis using data on the pools and fluxes of C and N in tree biomass, microbes, and soils from 1997 through 2002 collected at the Duke Forest free-air CO2 enrichment (FACE) experiment. Elevated CO2 stimulated NPP by 18-24% during the first six years of this experiment. Consistent with the hypothesis for PNL, significantly more N was immobilized in tree biomass and in the O horizon under elevated CO2. In contrast to the PNL hypothesis, microbial-N immobilization did not increase under elevated CO2, and although the rate of net N mineralization declined through time, the decline was not significantly more rapid under elevated CO2. Ecosystem C-to-N ratios widened more rapidly under elevated CO2 than ambient CO2 indicating a more rapid rate of C fixation per unit of N, a processes that could delay PNL in this ecosystem. Mass balance calculations demonstrated a large accrual of ecosystem N capital. Is PNL occurring in this ecosystem and will NPP decline to levels under ambient CO2? The answer depends on the relative strength of tree biomass and O-horizon N immobilization vs. widening C-to-N ratios and ecosystem-N accrual as processes that drive and delay PNL, respectively. Only direct observations through time will definitively answer this question.

    View details for Web of Science ID 000236020000004

    View details for PubMedID 16634293

  • Trading water for carbon with biological sequestration SCIENCE Jackson, R. B., Jobbagy, E. G., Avissar, R., Roy, S. B., Barrett, D. J., Cook, C. W., Farley, K. A., Le Maitre, D. C., McCarl, B. A., Murray, B. C. 2005; 310 (5756): 1944-1947


    Carbon sequestration strategies highlight tree plantations without considering their full environmental consequences. We combined field research, synthesis of more than 600 observations, and climate and economic modeling to document substantial losses in stream flow, and increased soil salinization and acidification, with afforestation. Plantations decreased stream flow by 227 millimeters per year globally (52%), with 13% of streams drying completely for at least 1 year. Regional modeling of U.S. plantation scenarios suggests that climate feedbacks are unlikely to offset such water losses and could exacerbate them. Plantations can help control groundwater recharge and upwelling but reduce stream flow and salinize and acidify some soils.

    View details for DOI 10.1126/science.1119282

    View details for Web of Science ID 000234275400039

    View details for PubMedID 16373572

  • Hydrological consequences of eucalyptus afforestation in the argentine pampas WATER RESOURCES RESEARCH Engel, V., Jobbagy, E. G., Stieglitz, M., Williams, M., Jackson, R. B. 2005; 41 (10)
  • From icy roads to salty streams PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Jackson, R. B., Jobbagy, E. G. 2005; 102 (41): 14487-14488

    View details for DOI 10.1073/pnas.0507389102

    View details for Web of Science ID 000232603600005

    View details for PubMedID 16203970

    View details for PubMedCentralID PMC1253603

  • Effects of afforestation on water yield: a global synthesis with implications for policy GLOBAL CHANGE BIOLOGY Farley, K. A., Jobbagy, E. G., Jackson, R. B. 2005; 11 (10): 1565-1576
  • Responses of tropical native and invader C-4 grasses to water stress, clipping and increased atmospheric CO2 concentration OECOLOGIA Baruch, Z., Jackson, R. B. 2005; 145 (4): 522-532


    The invasion of African grasses into Neotropical savannas has altered savanna composition, structure and function. The projected increase in atmospheric CO(2) concentration has the potential to further alter the competitive relationship between native and invader grasses. The objective of this study was to quantify the responses of two populations of a widespread native C(4) grass (Trachypogon plumosus) and two African C(4) grass invaders (Hyparrhenia rufa and Melinis minutiflora) to high CO(2) concentration interacting with two primary savanna stressors: drought and herbivory. Elevated CO(2) increased the competitive potential of invader grasses in several ways. Germination and seedling size was promoted in introduced grasses. Under high CO(2), the relative growth rate of young introduced grasses was twice that of native grass (0.58 g g(-1) week(-1) vs 0.25 g g(-1) week(-1)). This initial growth advantage was maintained throughout the course of the study. Well-watered and unstressed African grasses also responded more to high CO(2) than did the native grass (biomass increases of 21-47% compared with decreases of 13-51%). Observed higher water and nitrogen use efficiency of invader grasses may aid their establishment and competitive strength in unfertile sites, specially if the climate becomes drier. In addition, high CO(2) promoted lower leaf N content more in the invader grasses. The more intensive land use, predicted to occur in this region, may interact with high CO(2) to favor the African grasses, as they generally recovered faster after simulated herbivory. The superiority of invader grasses under high CO(2) suggests further increases in their competitive strength and a potential increased rate of displacement of the native savannas in the future by grasslands dominated by introduced African species.

    View details for DOI 10.1007/s00442-005-0153-x

    View details for Web of Science ID 000232559900002

    View details for PubMedID 16003505

  • Elevated CO2 reduces disease incidence and severity of a red maple fungal pathogen via changes in host physiology and leaf chemistry GLOBAL CHANGE BIOLOGY McElrone, A. J., Reid, C. D., Hoye, K. A., Hart, E., Jackson, R. B. 2005; 11 (10): 1828-1836
  • Assessment of soil microbial community structure by use of taxon-specific quantitative PCR assays APPLIED AND ENVIRONMENTAL MICROBIOLOGY Fierer, N., Jackson, J. A., Vilgalys, R., Jackson, R. B. 2005; 71 (7): 4117-4120


    Here we describe a quantitative PCR-based approach to estimating the relative abundances of major taxonomic groups of bacteria and fungi in soil. Primers were thoroughly tested for specificity, and the method was applied to three distinct soils. The technique provides a rapid and robust index of microbial community structure.

    View details for DOI 10.1128/AEM.71.7.4117-4120.2005

    View details for Web of Science ID 000230445700091

    View details for PubMedID 16000830

    View details for PubMedCentralID PMC1169028

  • Mapping the global distribution of deep roots in relation to climate and soil characteristics Annual Joint Conference of the Soil-and-Water-Conservation-Society/Soil-Science-Society-of-America Schenk, H. J., Jackson, R. B. ELSEVIER SCIENCE BV. 2005: 129–40
  • Genetic variance and covariance for physiological traits in Lobelia: Are there constraints on adaptive evolution? EVOLUTION Caruso, C. M., Maherali, H., Mikulyuk, A., Carlson, K., Jackson, R. B. 2005; 59 (4): 826-837


    Physiological traits that control the uptake of carbon dioxide and loss of water are key determinants of plant growth and reproduction. Variation in these traits is often correlated with environmental gradients of water, light, and nutrients, suggesting that natural selection is the primary evolutionary mechanism responsible for physiological diversification. Responses to selection, however, can be constrained by the amount of standing genetic variation for physiological traits and genetic correlations between these traits. To examine the potential for constraint on adaptive evolution, we estimated the quantitative genetic basis of physiological trait variation in one population of each of two closely related species (Lobelia siphilitica and L. cardinalis). Restricted maximum likelihood analyses of greenhouse-grown half-sib families were used to estimate genetic variances and covariances for seven traits associated with carbon and water relations. We detected significant genetic variation for all traits in L. siphilitica, suggesting that carbon-gain and water-use traits could evolve in response to natural selection in this population. In particular, narrow-sense heritabilities for photosynthetic rate (A), stomatal conductance (gs), and water-use efficiency (WUE) in our L. siphilitica population were high relative to previous studies in other species. Although there was significant narrow-sense heritability for A in L. cardinalis, we detected little genetic variation for traits associated with water use (gs and WUE), suggesting that our population of this species may be unable to adapt to drier environments. Despite being tightly linked functionally, the genetic correlation between A and gs was not strong and significant in either population. Therefore, our L. siphilitica population would not be genetically constrained from evolving high A (and thus fixing more carbon for growth and reproduction) while also decreasing gs to limit water loss. However, a significant negative genetic correlation existed between WUE and plant size in L. siphilitica, suggesting that high WUE may be negatively associated with high fecundity. In contrast, our results suggest that any constraints on the evolution of photosynthetic and stomatal traits of L. cardinalis are caused primarily by a lack of genetic variation, rather than by genetic correlations between these functionally related traits.

    View details for Web of Science ID 000228734300010

    View details for PubMedID 15926692

  • Ecohydrological implications of woody plant encroachment ECOLOGY Huxman, T. E., Wilcox, B. P., Breshears, D. D., Scott, R. L., Snyder, K. A., Small, E. E., Hultine, K., Pockman, W. T., Jackson, R. B. 2005; 86 (2): 308-319
  • Ecohydrological control of deep drainage in arid and semiarid regions ECOLOGY Seyfried, M. S., Schwinning, S., Walvoord, M. A., Pockman, W. T., Newman, B. D., Jackson, R. B., Phillips, E. M. 2005; 86 (2): 277-287
  • Carbon cycling in soil FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Johnston, C. A., Groffman, P., Breshears, D. D., Cardon, Z. G., Currie, W., Emanuel, W., Gaudinski, J., Jackson, R. B., Lajtha, K., Nadelhoffer, K., Nelson, D., Post, W. M., Retallack, G., Wielopolski, L. 2004; 2 (10): 522-528
  • Nutrient uptake as a contributing explanation for deep rooting in arid and semi-arid ecosystems OECOLOGIA McCulley, R. L., Jobbagy, E. G., Pockman, W. T., Jackson, R. B. 2004; 141 (4): 620-628


    Explanations for the occurrence of deep-rooted plants in arid and semi-arid ecosystems have traditionally emphasized the uptake of relatively deep soil water. However, recent hydrologic data from arid systems show that soil water potentials at depth fluctuate little over long time periods, suggesting this water may be rarely utilized or replenished. In this study, we examine the distributions of root biomass, soil moisture and nutrient contents to 10-m depths at five semi-arid and arid sites across southwestern USA. We couple these depth distributions with strontium (Sr) isotope data that show deep (>1 m) nutrient uptake is prevalent at four of the five sites. At all of the sites, the highest abundance of one or more of the measured nutrients occurred deep within the soil profile, particularly for P, Ca2+ and Mg2+. Phosphate contents were greater at depth than in the top meter of soil at three of five sites. At Jornada, for example, the 2-3 m depth increment had twice the extractable P as the top meter of soil, despite the highest concentrations of P occurring at the surface. The prevalence of such deep resource pools, and our evidence for cation uptake from them, suggest nutrient uptake as a complementary explanation for the occurrence of deep-rooted plants in arid and semi-arid systems. We propose that hydraulic redistribution of shallow surface water to deep soil layers by roots may be the mechanism through which deep soil nutrients are mobilized and taken up by plants.

    View details for DOI 10.1007/s00442-004-1687-z

    View details for Web of Science ID 000224999800008

    View details for PubMedID 15322902

  • Curbing the US carbon deficit PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Jackson, R. B., Schlesinger, W. H. 2004; 101 (45): 15827-15829


    The U.S. emitted approximately 1.58 petagrams (Pg) of fossil fuel carbon in 2001, approximately one-quarter of global CO(2) production. With climate change increasingly likely, strategies to reduce carbon emissions and stabilize climate are needed, including greater energy efficiency, renewable energy sources, geoengineering, decarbonization, and geological and biological sequestration. Two of the most commonly proposed biological strategies are restoring organic carbon in agricultural soils and using plantations to sequester carbon in soils and wood. Here, we compare scenarios of land-based sequestration to emissions reductions arising from increased fuel efficiency in transportation, targeting ways to reduce net U.S. emissions by 10% ( approximately 0.16 Pg of carbon per year). Based on mean sequestration rates, converting all U.S. croplands to no-till agriculture or retiring them completely could sequester approximately 0.059 Pg of carbon per year for several decades. Summary data across a range of plantations reveal an average rate of carbon storage an order of magnitude larger than in agricultural soils; in consequence, one-third of U.S. croplands or 44 million hectares would be needed for plantations to reach the target of approximately 0.16 Pg of carbon per year. For fossil fuel reductions, cars and light trucks generated approximately 0.31 Pg of carbon in U.S. emissions in 2001. To reduce net emissions by 0.16 Pg of carbon per year, a doubling of fuel efficiency for cars and light trucks is needed, a change feasible with current technology. Issues of permanence, leakage, and economic potentials are discussed briefly, as is the recognition that such scenarios are only a first step in addressing total U.S. emissions.

    View details for DOI 10.1073/pnas.0403631101

    View details for Web of Science ID 000225196800002

    View details for PubMedID 15514026

    View details for PubMedCentralID PMC528743

  • Nitric oxide represses the Arabidopsis floral transition SCIENCE He, Y. K., Tang, R. H., Hao, Y., Stevens, R. D., Cook, C. W., Am, S. M., Jing, L. F., Yang, Z. G., Chen, L. G., Guo, F. Q., Fiorani, F., Jackson, R. B., Crawford, N. M., Pei, Z. M. 2004; 305 (5692): 1968-1971


    The correct timing of flowering is essential for plants to maximize reproductive success and is controlled by environmental and endogenous signals. We report that nitric oxide (NO) repressed the floral transition in Arabidopsis thaliana. Plants treated with NO, as well as a mutant overproducing NO (nox1), flowered late, whereas a mutant producing less NO (nos1) flowered early. NO suppressed CONSTANS and GIGANTEA gene expression and enhanced FLOWERING LOCUS C expression, which indicated that NO regulates the photoperiod and autonomous pathways. Because NO is induced by environmental stimuli and constitutively produced, it may integrate both external and internal cues into the floral decision.

    View details for Web of Science ID 000224136000051

    View details for PubMedID 15448272

  • The uplift of soil nutrients by plants: Biogeochemical consequences across scales ECOLOGY Jobbagy, E. G., Jackson, R. B. 2004; 85 (9): 2380-2389
  • Terrestrial and freshwater biogeochemistry ECOLOGY Jackson, R. B., Hedin, L. O. 2004; 85 (9): 2353-2354
  • Variation in xylem structure and function in stems and roots of trees to 20 m depth NEW PHYTOLOGIST McElrone, A. J., Pockman, W. T., Martinez-Vilalta, J., Jackson, R. B. 2004; 163 (3): 507-517
  • Adaptive variation in the vulnerability of woody plants to xylem cavitation ECOLOGY Maherali, H., Pockman, W. T., Jackson, R. B. 2004; 85 (8): 2184-2199
  • Groundwater use and salinization with grassland afforestation GLOBAL CHANGE BIOLOGY Jobbagy, E. G., Jackson, R. B. 2004; 10 (8): 1299-1312
  • Disconnects in evaluating the relative effectiveness of conservation strategies CONSERVATION BIOLOGY Saterson, K. A., Christensen, N. L., Jackson, R. B., Kramer, R. A., Pimm, S. L., Smith, M. D., Wiener, J. B. 2004; 18 (3): 597-599
  • Comment on "A reservoir of nitrate beneath desert soils" SCIENCE Jackson, R. B., Berthrong, S. T., Cook, C. W., Jobbagy, E. G., McCulley, R. L. 2004; 304 (5667)

    View details for Web of Science ID 000220567900025

    View details for PubMedID 15060308

  • Regional feedbacks among fire, climate, and tropical deforestation JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES Hoffmann, W. A., Schroeder, W., Jackson, R. B. 2003; 108 (D23)
  • On the relationship between stomatal characters and atmospheric CO2 GEOPHYSICAL RESEARCH LETTERS Reid, C. D., Maherali, H., Johnson, H. B., Smith, S. D., Wullschleger, S. D., Jackson, R. B. 2003; 30 (19)
  • Defining a plant's belowground zone of influence ECOLOGY Casper, B. B., Schenk, H. J., Jackson, R. B. 2003; 84 (9): 2313-2321
  • Stomatal sensitivity to vapour pressure difference over a subambient to elevated CO2 gradient in a C-3/C-4 grassland PLANT CELL AND ENVIRONMENT Maherali, H., Johnson, H. B., Jackson, R. B. 2003; 26 (8): 1297-1306
  • Patterns and mechanisms of soil acidification in the conversion of grasslands to forests BIOGEOCHEMISTRY Jobbagy, E. G., Jackson, R. B. 2003; 64 (2): 205-229
  • Gender-specific floral and physiological traits: implications for the maintenance of females in gynodioecious Lobelia siphilitica OECOLOGIA Caruso, C. M., Maherali, H., Jackson, R. B. 2003; 135 (4): 524-531


    A common gender dimorphism in angiosperms is gynodioecy, in which hermaphrodites and females co-occur. Females are at an inherent disadvantage because they can transmit their genes only through ovule production. One mechanism by which females can compensate for the loss of male function is by producing more seeds than hermaphrodites. As such, females should: (1) increase resource uptake to support higher seed production; and (2) allocate resources saved by the loss of male function to seed production. To test this hypothesis, we measured physiological and floral traits of gynodioecious Lobelia siphilitica, controlling for both environmental and genetic variation through a comparison of greenhouse-grown siblings. Pre-reproductive females had 14% higher area-based (Z=2.14; P=0.04) and 32% higher mass-based (Z=1.96; P=0.05) photosynthetic rate than hermaphrodites, suggesting that they have increased carbon acquisition by altering photosynthetic physiology. Female L. siphilitica produced flowers with 4-8% smaller corollas than hermaphrodites (all P<0.05), suggesting that females allocate resources away from floral structures used for pollinator attraction. The genetic correlation between genders for four floral and four physiological traits was significantly less than one but greater than zero, indicating that the evolution of gender dimorphism in response to sex-differential selection will be constrained. The allocation of resources saved by the loss of male function has been viewed as the most important mechanism allowing females of gynodioecious species to support higher seed production. Our data suggest that increased resource acquisition by females at pre-reproductive stages can also contribute to the maintenance of gender dimorphism in gynodioecious species.

    View details for DOI 10.1007/s00442-003-1199-2

    View details for Web of Science ID 000183722700005

    View details for PubMedID 16228251

  • Positive feedbacks of fire, climate, and vegetation and the conversion of tropical savanna GEOPHYSICAL RESEARCH LETTERS Hoffmann, W. A., Schroeder, W., Jackson, R. B. 2002; 29 (22)
  • Meeting ecological and societal needs for freshwater ECOLOGICAL APPLICATIONS Baron, J. S., Poff, N. L., Angermeier, P. L., Dahm, C. N., Gleick, P. H., Hairston, N. G., Jackson, R. B., Johnston, C. A., Richter, B. D., Steinman, A. D. 2002; 12 (5): 1247-1260
  • Linking molecular insight and ecological research TRENDS IN ECOLOGY & EVOLUTION Jackson, R. B., Linder, C. R., Lynch, M., Purugganan, M., Somerville, S., Thayer, S. S. 2002; 17 (9): 409-414
  • Root production and demography in a california annual grassland under elevated atmospheric carbon dioxide GLOBAL CHANGE BIOLOGY Higgins, P. A., Jackson, R. B., Des Rosiers, J. M., Field, C. B. 2002; 8 (9): 841-850
  • Ecosystem carbon loss with woody plant invasion of grasslands NATURE Jackson, R. B., Banner, J. L., Jobbagy, E. G., Pockman, W. T., Wall, D. H. 2002; 418 (6898): 623-626


    The invasion of woody vegetation into deserts, grasslands and savannas is generally thought to lead to an increase in the amount of carbon stored in those ecosystems. For this reason, shrub and forest expansion (for example, into grasslands) is also suggested to be a substantial, if uncertain, component of the terrestrial carbon sink. Here we investigate woody plant invasion along a precipitation gradient (200 to 1,100 mm yr(-1)) by comparing carbon and nitrogen budgets and soil delta(13)C profiles between six pairs of adjacent grasslands, in which one of each pair was invaded by woody species 30 to 100 years ago. We found a clear negative relationship between precipitation and changes in soil organic carbon and nitrogen content when grasslands were invaded by woody vegetation, with drier sites gaining, and wetter sites losing, soil organic carbon. Losses of soil organic carbon at the wetter sites were substantial enough to offset increases in plant biomass carbon, suggesting that current land-based assessments may overestimate carbon sinks. Assessments relying on carbon stored from woody plant invasions to balance emissions may therefore be incorrect.

    View details for DOI 10.1038/nature00910

    View details for Web of Science ID 000177305600038

    View details for PubMedID 12167857

  • The global biogeography of roots ECOLOGICAL MONOGRAPHS Schenk, H. J., Jackson, R. B. 2002; 72 (3): 311-328
  • Rooting depths, lateral root spreads and below-ground/above-ground allometries of plants in water-limited ecosystems JOURNAL OF ECOLOGY Schenk, H. J., Jackson, R. B. 2002; 90 (3): 480-494
  • Nonlinear grassland responses to past and future atmospheric CO2 NATURE Gill, R. A., Polley, H. W., Johnson, H. B., Anderson, L. J., Maherali, H., Jackson, R. B. 2002; 417 (6886): 279-282


    Carbon sequestration in soil organic matter may moderate increases in atmospheric CO(2) concentrations (C(a)) as C(a) increases to more than 500 micromol mol(-1) this century from interglacial levels of less than 200 micromol mol(-1) (refs 1 6). However, such carbon storage depends on feedbacks between plant responses to C(a) and nutrient availability. Here we present evidence that soil carbon storage and nitrogen cycling in a grassland ecosystem are much more responsive to increases in past C(a) than to those forecast for the coming century. Along a continuous gradient of 200 to 550 micromol mol(-1) (refs 9, 10), increased C(a) promoted higher photosynthetic rates and altered plant tissue chemistry. Soil carbon was lost at subambient C(a), but was unchanged at elevated C(a) where losses of old soil carbon offset increases in new carbon. Along the experimental gradient in C(a) there was a nonlinear, threefold decrease in nitrogen availability. The differences in sensitivity of carbon storage to historical and future C(a) and increased nutrient limitation suggest that the passive sequestration of carbon in soils may have been important historically, but the ability of soils to continue as sinks is limited.

    View details for DOI 10.1038/417279a

    View details for Web of Science ID 000175592100045

    View details for PubMedID 12015601

  • Stomatal acclimation over a subambient to elevated CO2 gradient in a C-3/C-4 grassland PLANT CELL AND ENVIRONMENT Maherali, H., Reid, C. D., Polley, H. W., Johnson, H. B., Jackson, R. B. 2002; 25 (4): 557-566
  • Nitrogen controls on climate model evapotranspiration JOURNAL OF CLIMATE Dickinson, R. E., Berry, J. A., Bonan, G. B., Collatz, G. J., Field, C. B., Fung, I. Y., Goulden, M., Hoffmann, W. A., Jackson, R. B., Myneni, R., Sellers, P. J., Shaikh, M. 2002; 15 (3): 278-295
  • The Earth Remains Forever Jackson, R. University of Texas Press. 2002
  • Using simple environmental variables to estimate below-ground productivity in grasslands GLOBAL ECOLOGY AND BIOGEOGRAPHY Gill, R. A., Kelly, R. H., Parton, W. J., Day, K. A., Jackson, R. B., Morgan, J. A., Scurlock, J. M., Tieszen, L. L., Castle, J. V., Ojima, D. S., Zhang, X. S. 2002; 11 (1): 79-86
  • Below-ground processes in gap models for simulating forest response to global change CLIMATIC CHANGE Wullschleger, S. D., Jackson, R. B., Currie, W. S., Friend, A. D., Luo, Y., Mouillot, F., Pan, Y., Shao, G. F. 2001; 51 (3-4): 449-473
  • Modeling root water uptake in hydrological and climate models BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY Feddes, R. A., Hoff, H., Bruen, M., Dawson, T., de Rosnay, P., Dirmeyer, O., Jackson, R. B., Kabat, P., Kleidon, A., Lilly, A., Pitman, A. J. 2001; 82 (12): 2797-2809
  • Water in a changing world ECOLOGICAL APPLICATIONS Jackson, R. B., Carpenter, S. R., Dahm, C. N., McKnight, D. M., Naiman, R. J., Postel, S. L., Running, S. W. 2001; 11 (4): 1027-1045
  • Gas exchange and photosynthetic acclimation over subambient to elevated CO2 in a C-3-C-4 grassland GLOBAL CHANGE BIOLOGY Anderson, L. J., Maherali, H., Johnson, H. B., Polley, H. W., Jackson, R. B. 2001; 7 (6): 693-707
  • The distribution of soil nutrients with depth: Global patterns and the imprint of plants BIOGEOCHEMISTRY Jobbagy, E. G., Jackson, R. B. 2001; 53 (1): 51-77
  • Plant physiological ecology: linking the organism to scales above and below - Ecological Society of America Meeting Snowbird, UT, USA, August 2000 NEW PHYTOLOGIST DeLucia, E. H., Coleman, J. S., Dawson, T. E., Jackson, R. B. 2001; 149 (1): 12-16
  • Water and tree-understory interactions: A natural experiment in a savanna with oak wilt ECOLOGY Anderson, L. J., Brumbaugh, M. S., Jackson, R. B. 2001; 82 (1): 33-49
  • Heterogenous soil-resource distribution and plant responses - from individual-plant growth to ecosystem functioning Progress in Botany Huber-Sannwald, E., Jackson, R. B. 2001; 62: 451-476
  • Reduction of isoprene emissions from live oak (Quercus fusiformis) with oak wilt TREE PHYSIOLOGY Anderson, L. J., Harley, P. C., Monson, R. K., Jackson, R. B. 2000; 20 (17): 1199-1203
  • Root water uptake and transport: using physiological processes in global predictions TRENDS IN PLANT SCIENCE Jackson, R. B., Sperry, J. S., Dawson, T. E. 2000; 5 (11): 482-488


    Plant water loss, regulated by stomata and driven by atmospheric demand, cannot exceed the maximum steady-state supply through roots. Just as an electric circuit breaks when carrying excess current, the soil-plant continuum breaks if forced to transport water beyond its capacity. Exciting new molecular, biophysical and ecological research suggests that roots are the weakest link along this hydraulic flow path. We attempt here to predict rooting depth and water uptake using the hydraulic properties of plants and the soil, and also to suggest how new physiological tools might contribute to larger-scale studies of hydraulic lift, the water balance and biosphere-atmosphere interactions.

    View details for Web of Science ID 000165268000017

    View details for PubMedID 11077257

  • A universal molecular method for identifying underground plant parts to species MOLECULAR ECOLOGY Linder, C. R., Moore, L. A., Jackson, R. B. 2000; 9 (10): 1549-1559


    As part of a large project to determine rooting depth and resource uptake on the Edwards Plateau of central Texas, we developed a DNA-based technique that allows the below-ground parts of all plants to be identified to the level of genus and usually to species. Identification is achieved by comparing DNA sequences of the internal transcribed spacer (ITS) region of the 18S-26S nuclear ribosomal DNA repeat, derived from below-ground plant material, with a reference ITS region database for plants at a site. The method works throughout plants because the plant ITS region can be PCR amplified using a set of universal primers. Congeneric species can usually be identified because the ITS region evolves relatively rapidly. In our study, all roots were easily identified to the level of genus; most congeneric species were identified solely by ITS sequence differences but some required a combination of ITS sequence data and above-ground surveys of species at a site. In addition to showing the feasibility and efficacy of our technique, we compare it with another DNA-based technique used to identify below-ground plant parts. Finally, we also describe a DNA extraction and purification technique that reliably provides high-quality DNA of sufficient quantity from roots so that PCR can be readily accomplished. Our technique should allow the below-ground parts of plants in any system to be identified and thereby open new possibilities for the study of below-ground plant communities.

    View details for Web of Science ID 000089998600010

    View details for PubMedID 11050550

  • Global patterns of root turnover for terrestrial ecosystems NEW PHYTOLOGIST Gill, R. A., Jackson, R. B. 2000; 147 (1): 13-31
  • Root dynamics and global change: seeking an ecosystem perspective NEW PHYTOLOGIST Norby, R. J., Jackson, R. B. 2000; 147 (1): 3-12
  • Vegetation-climate feedbacks in the conversion of tropical savanna to grassland JOURNAL OF CLIMATE Hoffmann, W. A., Jackson, R. B. 2000; 13 (9): 1593-1602
  • Elevated CO2 enhances resprouting of a tropical savanna tree OECOLOGIA Hoffmann, W. A., Bazzaz, F. A., Chatterton, N. J., Harrison, P. A., Jackson, R. B. 2000; 123 (3): 312-317


    The savannas (cerrado) of south-central Brazil are currently subjected to frequent anthropogenic burning, causing widespread reduction in tree density. Increasing concentrations of atmospheric CO2 could reduce the impact of such frequent burning by increasing the availability of nonstructural carbohydrate, which is necessary for resprouting. We tested the hypotheses that elevated CO2 stimulates resprouting and accelerates replenishment of carbohydrate reserves. Using a factorial experiment, seedlings of a common Brazilian savanna tree, Keilmeyera coriacea, were grown at 350 ppm and 700 ppm CO2 and at two nutrient levels. To simulate burning, the plants were either clipped at 15 weeks or were left unclipped. Among unclipped plants, CO2 and nutrients both stimulated growth, with no significant interaction between nutrient and CO2 effects. Among clipped plants, both CO2 and nutrients stimulated resprouting. However, there was a strong interaction between CO2 and nutrient effects, with CO2 having a significant effect only in the presence of high nutrient availability. Under elevated CO2, carbohydrate reserves remained at higher levels following clipping. Root total nonstructural carbohydrate remained above 36% in all treatments, so carbohydrate reserves did not limit regrowth. These results indicate that under elevated CO2 this species may be better able to endure the high frequency of anthropogenic burning in the Brazilian savannas.

    View details for Web of Science ID 000087882600002

  • Global controls of forest line elevation in the northern and southern hemispheres GLOBAL ECOLOGY AND BIOGEOGRAPHY Jobbagy, E. G., Jackson, R. B. 2000; 9 (3): 253-268
  • The vertical distribution of soil organic carbon and its relation to climate and vegetation ECOLOGICAL APPLICATIONS Jobbagy, E. G., Jackson, R. B. 2000; 10 (2): 423-436
  • Belowground processes and global change ECOLOGICAL APPLICATIONS Jackson, R. B. 2000; 10 (2): 397-398
  • Belowground consequences of vegetation change and their treatment in models ECOLOGICAL APPLICATIONS Jackson, R. B., Schenk, H. J., Jobbagy, E. G., Canadell, J., Colello, G. D., Dickinson, R. E., Field, C. B., Friedlingstein, P., Heimann, M., Hibbard, K., Kicklighter, D. W., Kleidon, A., Neilson, R. P., Parton, W. J., Sala, O. E., Sykes, M. T. 2000; 10 (2): 470-483
  • Biodiversity - Global biodiversity scenarios for the year 2100 SCIENCE Sala, O. E., Chapin, F. S., Armesto, J. J., Berlow, E., Bloomfield, J., Dirzo, R., Huber-Sanwald, E., Huenneke, L. F., Jackson, R. B., Kinzig, A., Leemans, R., Lodge, D. M., Mooney, H. A., Oesterheld, M., Poff, N. L., Sykes, M. T., Walker, B. H., Walker, M., Wall, D. H. 2000; 287 (5459): 1770-1774


    Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.

    View details for Web of Science ID 000085775300030

  • Carbon metabolism of the terrestrial biosphere: A multitechnique approach for improved understanding ECOSYSTEMS Canadell, J. G., Mooney, H. A., Baldocchi, D. D., Berry, J. A., Ehleringer, J. R., Field, C. B., Gower, S. T., Hollinger, D. Y., Hunt, J. E., Jackson, R. B., Running, S. W., Shaver, G. R., STEFFEN, W., Trumbore, S. E., Valentini, R., Bond, B. Y. 2000; 3 (2): 115-130
  • Methods in Ecosystem Science edited by Sala, O. E., Jackson, R. B., Mooney, H. A., Howarth, R. W. Springer. 2000
  • Nutrient concentrations in fine roots ECOLOGY Gordon, W. S., Jackson, R. B. 2000; 81 (1): 275-280
  • Ecosystem rooting depth determined with caves and DNA PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Jackson, R. B., Moore, L. A., Hoffmann, W. A., Pockman, W. T., Linder, C. R. 1999; 96 (20): 11387-11392


    Belowground vertical community composition and maximum rooting depth of the Edwards Plateau of central Texas were determined by using DNA sequence variation to identify roots from caves 5-65 m deep. Roots from caves were identified by comparing their DNA sequences for the internal transcribed spacer (ITS) region of the 18S-26S ribosomal DNA repeat against a reference ITS database developed for woody plants of the region. Sequencing the ITS provides, to our knowledge, the first universal method for identifying plant roots. At least six tree species in the system grew roots deeper than 5 m, but only the evergreen oak, Quercus fusiformis, was found below 10 m. The maximum rooting depth for the ecosystem was approximately 25 m. (18)O isotopic signatures for stem water of Q. fusiformis confirmed water uptake from 18 m underground. The availability of resources at depth, coupled with small surface pools of water and nutrients, may explain the occurrence of deep roots in this and other systems.

    View details for Web of Science ID 000082868500085

    View details for PubMedID 10500186

  • Interactive effects of water stress and elevated CO2 on growth, photosynthesis, and water use efficiency Carbon Dioxide and Environmental Stress Hsiao, T. C., Jackson, R. B. Academic Press. 1999: 3–31
  • Desertification control to sequester C and mitigate the greenhouse effect: a commentary Carbon sequestration in soils: science, monitoring, and beyond Jackson, R. B. Batelle Press. 1999: 143–146
  • The structure and function of root systems Handbook of Functional Plant Ecology Jackson, R. B., Pockman, W. T., Hoffmann, W. A. Marcel Dekker. 1999: 195–220
  • The importance of root distributions for hydrology, biogeochemistry, and ecosystem functioning Integrating hydrology, ecosystem dynamics, and biogeochemistry in complex landscapes Jackson, R. B. John Wiley and Sons. 1999: 219–240
  • Downward flux of water through roots (ie inverse hydraulic lift) in dry Kalahari sands OECOLOGIA Schulze, E. D., Caldwell, M. M., Canadell, J., Mooney, H. A., Jackson, R. B., Parson, D., Scholes, R., Sala, O. E., Trimborn, P. 1998; 115 (4): 460-462
  • Ecosystem water fluxes for two grasslands in elevated CO2: a modeling analysis OECOLOGIA Jackson, R. B., Sala, O. E., Paruelo, J. M., Mooney, H. A. 1998; 113 (4): 537-546
  • The fate of carbon in grasslands under carbon dioxide enrichment NATURE Hungate, B. A., Holland, E. A., Jackson, R. B., Chapin, F. S., Mooney, H. A., Field, C. B. 1997; 388 (6642): 576-579
  • A global budget for fine root biomass, surface area, and nutrient contents PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Jackson, R. B., Mooney, H. A., Schulze, E. D. 1997; 94 (14): 7362-7366


    Global biogeochemical models have improved dramatically in the last decade in their representation of the biosphere. Although leaf area data are an important input to such models and are readily available globally, global root distributions for modeling water and nutrient uptake and carbon cycling have not been available. This analysis provides global distributions for fine root biomass, length, and surface area with depth in the soil, and global estimates of nutrient pools in fine roots. Calculated root surface area is almost always greater than leaf area, more than an order of magnitude so in grasslands. The average C:N:P ratio in living fine roots is 450:11:1, and global fine root carbon is more than 5% of all carbon contained in the atmosphere. Assuming conservatively that fine roots turn over once per year, they represent 33% of global annual net primary productivity.

    View details for Web of Science ID A1997XJ87600044

    View details for PubMedID 11038557

  • Photosynthetic electron transport in single guard cells as measured by scanning electrochemical microscopy PLANT PHYSIOLOGY Tsionsky, M., Cardon, Z. G., Bard, A. J., Jackson, R. B. 1997; 113 (3): 895-901
  • Plant competition underground ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS Casper, B. B., Jackson, R. B. 1997; 28: 545-570
  • Integrating resource heterogeneity and plant plasticity: Modelling nitrate and phosphate uptake in a patchy soil environment JOURNAL OF ECOLOGY Jackson, R. B., Caldwell, M. M. 1996; 84 (6): 891-903
  • Maximum rooting depth of vegetation types at the global scale OECOLOGIA Canadell, J., Jackson, R. B., Ehleringer, J. R., Mooney, H. A., Sala, O. E., Schulze, E. D. 1996; 108 (4): 583-595
  • A global analysis of root distributions for terrestrial biomes OECOLOGIA Jackson, R. B., Canadell, J., Ehleringer, J. R., Mooney, H. A., Sala, O. E., Schulze, E. D. 1996; 108 (3): 389-411
  • Rooting depth, water availability, and vegetation cover along an aridity gradient in Patagonia OECOLOGIA Schulze, E. D., Mooney, H. A., Sala, O. E., Jobbagy, E., Buchmann, N., Bauer, G., Canadell, J., Jackson, R. B., Loreti, J., Oesterheld, M., Ehleringer, J. R. 1996; 108 (3): 503-511
  • Elevated CO2 increases belowground respiration in California grasslands OECOLOGIA Luo, Y. Q., Jackson, R. B., Field, C. B., Mooney, H. A. 1996; 108 (1): 130-137


    This study was designed to identify potential effects of elevated CO2 on belowground respiration (the sum of root and heterotrophic respiration) in field and microcosm ecosystems and on the annual carbon budget. We made three sets of respiration measurements in two CO2 treatments, i.e., (1) monthly in the sandstone grassland and in microcosms from November 1993 to June 1994; (2) at the annual peak of live biomass (March and April) in the serpentine and sandstone grasslands in 1993 and 1994; and (3) at peak biomass in the microcosms with monocultures of seven species in 1993. To help understand ecosystem carbon cycling, we also made supplementary measurements of belowground respiration monthly in sandstone and serpentine grasslands located within 500 m of the CO2 experiment site. The seasonal average respiration rate in the sandstone grassland was 2.12 μmol m(-2) s(-1) in elevated CO2, which was 42% higher than the 1.49 μmol m(-2) s(-1) measured in ambient CO2 (P=0.007). Studies of seven individual species in the microcosms indicated that respiration was positively correlated with plant biomass and increased, on average, by 70% with CO2. Monthly measurements revealed a strong seasonality in belowground respiration, being low (0-0.5 μmol CO2 m(-2) s(-1) in the two grasslands adjacent to the CO2 site) in the summer dry season and high (2-4 μmol CO2 m(-2) s(-1) in the sandstone grassland and 2-7 μmol CO2 m(-2) s(-1) in the microcosms) during the growing season from the onset of fall rains in November to early spring in April and May. Estimated annual carbon effluxes from the soil were 323 and 440 g C m(-2) year(-1) for the sandstone grasslands in ambient and elevated CO2. That CO2-stimulated increase in annual soil carbon efflux is more than twice as big as the increase in aboveground net primary productivity (NPPa) and approximately 60% of NPPa in this grassland in the current CO2 environment. The results of this study suggest that below-ground respiration can dissipate most of the increase in photosynthesis stimulated by elevated CO2.

    View details for Web of Science ID A1996VL38300017

  • Detecting changes in soil carbon in CO2 enrichment experiments International GCTE Workshop on Plant-Soil Carbon Below Ground: The Effects of Elevated Carbon Dioxide Hungate, B. A., Jackson, R. B., Field, C. B., Chapin, F. S. SPRINGER. 1996: 135–45
  • Nitrate and ammonium uptake for single- and mixed-species communities grown at elevated CO2 OECOLOGIA Jackson, R. B., Reynolds, H. L. 1996; 105 (1): 74-80
  • Photosynthesis, growth and density for the dominant species in a CO2-enriched grassland 1st Global Change and Terrestrial Ecosystems Science Conference Jackson, R. B., Luo, Y., Cardon, Z. G., Sala, O. E., Field, C. B., Mooney, H. A. WILEY-BLACKWELL PUBLISHING, INC. 1995: 221–25
  • The soil system Global Biodiversity Assessment Anderson, J. M., Cuevas, E., Chapin III, F. S., Hobbs, R. J., Pitelka, L. F., Jackson, R. B. Cambridge University Press. 1995: 406–412
  • Local regulation of mycorrhizal arbuscule frequency in enriched soil microsites Canadian Journal of Botany Duke, S. E., Jackson, R. B., Caldwell, M. M. 1994; 72: 998-1001
  • Nonsteady-state photosynthesis following an increase in photon flux density (PFD): effects of magnitude and duration of initial photon flux density Plant Physiology Jackson, R. B., Woodrow, I. E., Mott, K. A. 1991; 95: 498-503


    SOIL microsites rich in available nutrients are an important source of mineral nutrients for plants in many environments(1-5). Patchiness in nutrient availability below ground is analogous to resource availability in canopy gaps above ground(6). Although the physiological changes occurring in leaves exposed to sun and shade in canopy gaps are well known(7-9), we do not know any studies that show similar physiological changes in roots in enriched soil patches. Here we present evidence of large and rapid increases in the uptake kinetics of plant roots after creating nutrient-rich soil patches in the field. The mean rate of phosphate uptake at a given external phosphate concentration increased by as much as 80% for roots from enriched soil patches compared with roots of control patches treated with distilled water. The changes took place within days of patch treatment. This degree of plasticity was particularly notable for plants growing in soils of very low available phosphorus. These results showing rapid physiological plasticity of roots in fertile soil microsites have important implications for the theory and modelling of nutrient uptake in all soils.

    View details for Web of Science ID A1990CQ97200059

    View details for PubMedID 18278027

  • The timing and degree of root proliferation in fertile-soil microsites for three cold-desert perennials Oecologia Jackson, R. B., Caldwell, M. M. 1989; 81: 149-153