Bio


My research focuses on multi-scale effects of global change on vegetation and carbon cycling in ecosystems. In the past, I have investigated the influence of drought, permafrost thaw or warming on above and belowground plant dynamics, greenhouse gas fluxes and litter decomposition. I am also interested in regional to global-scale drivers of carbon sequestration. My toolkit draws from ecosystem ecology, biogeochemistry and systems thinking and I specialize in carbon-rich systems such as northern peatlands.

My postdoctoral research in the Jackson lab focuses on 1) global upscaling of greenhouse gas fluxes from peatlands and 2) the fate of root-derived carbon in soils from continental to global scales.

Professional Education


  • Doctor of Philosophy, McGill University (2016)
  • Master of Science, Villanova University (2010)
  • Bachelor of Science, York University (2007)

All Publications


  • Peatland warming strongly increases fine-root growth. Proceedings of the National Academy of Sciences of the United States of America Malhotra, A., Brice, D. J., Childs, J., Graham, J. D., Hobbie, E. A., Vander Stel, H., Feron, S. C., Hanson, P. J., Iversen, C. M. 2020

    Abstract

    Belowground climate change responses remain a key unknown in the Earth system. Plant fine-root response is especially important to understand because fine roots respond quickly to environmental change, are responsible for nutrient and water uptake, and influence carbon cycling. However, fine-root responses to climate change are poorly constrained, especially in northern peatlands, which contain up to two-thirds of the world's soil carbon. We present fine-root responses to warming between +2 °C and 9 °C above ambient conditions in a whole-ecosystem peatland experiment. Warming strongly increased fine-root growth by over an order of magnitude in the warmest treatment, with stronger responses in shrubs than in trees or graminoids. In the first year of treatment, the control (+0 °C) shrub fine-root growth of 0.9 km m-2 y-1 increased linearly by 1.2 km m-2 y-1 (130%) for every degree increase in soil temperature. An extended belowground growing season accounted for 20% of this dramatic increase. In the second growing season of treatment, the shrub warming response rate increased to 2.54 km m-2 °C-1 Soil moisture was negatively correlated with fine-root growth, highlighting that drying of these typically water-saturated ecosystems can fuel a surprising burst in shrub belowground productivity, one possible mechanism explaining the "shrubification" of northern peatlands in response to global change. This previously unrecognized mechanism sheds light on how peatland fine-root response to warming and drying could be strong and rapid, with consequences for the belowground growing season duration, microtopography, vegetation composition, and ultimately, carbon function of these globally relevant carbon sinks.

    View details for DOI 10.1073/pnas.2003361117

    View details for PubMedID 32661144

  • Thaw Transitions and Redox Conditions Drive Methane Oxidation in a Permafrost Peatland JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES Perryman, C. R., Mccalley, C. K., Malhotra, A., Fahnestock, M., Kashi, N. N., Bryce, J. G., Giesler, R., Varner, R. K. 2020; 125 (3)
  • Fast plants in deep water: introducing the whole-soil column perspective. The New phytologist Tumber-Davila, S. J., Malhotra, A. 2020; 225 (1): 7–9

    View details for DOI 10.1111/nph.16302

    View details for PubMedID 31788820

  • COSORE: A community database for continuous soil respiration and other soil-atmosphere greenhouse gas flux data. Global change biology Bond-Lamberty, B., Christianson, D. S., Malhotra, A., Pennington, S. C., Sihi, D., AghaKouchak, A., Anjileli, H., Altaf Arain, M., Armesto, J. J., Ashraf, S., Ataka, M., Baldocchi, D., Andrew Black, T., Buchmann, N., Carbone, M. S., Chang, S. C., Crill, P., Curtis, P. S., Davidson, E. A., Desai, A. R., Drake, J. E., El-Madany, T. S., Gavazzi, M., Görres, C. M., Gough, C. M., Goulden, M., Gregg, J., Gutiérrez Del Arroyo, O., He, J. S., Hirano, T., Hopple, A., Hughes, H., Järveoja, J., Jassal, R., Jian, J., Kan, H., Kaye, J., Kominami, Y., Liang, N., Lipson, D., Macdonald, C. A., Maseyk, K., Mathes, K., Mauritz, M., Mayes, M. A., McNulty, S., Miao, G., Migliavacca, M., Miller, S., Miniat, C. F., Nietz, J. G., Nilsson, M. B., Noormets, A., Norouzi, H., O'Connell, C. S., Osborne, B., Oyonarte, C., Pang, Z., Peichl, M., Pendall, E., Perez-Quezada, J. F., Phillips, C. L., Phillips, R. P., Raich, J. W., Renchon, A. A., Ruehr, N. K., Sánchez-Cañete, E. P., Saunders, M., Savage, K. E., Schrumpf, M., Scott, R. L., Seibt, U., Silver, W. L., Sun, W., Szutu, D., Takagi, K., Takagi, M., Teramoto, M., Tjoelker, M. G., Trumbore, S., Ueyama, M., Vargas, R., Varner, R. K., Verfaillie, J., Vogel, C., Wang, J., Winston, G., Wood, T. E., Wu, J., Wutzler, T., Zeng, J., Zha, T., Zhang, Q., Zou, J. 2020

    Abstract

    Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil-to-atmosphere CO2 flux, commonly though imprecisely termed soil respiration (RS ), is one of the largest carbon fluxes in the Earth system. An increasing number of high-frequency RS measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open-source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long-term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measured RS , the database design accommodates other soil-atmosphere measurements (e.g. ecosystem respiration, chamber-measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package.

    View details for DOI 10.1111/gcb.15353

    View details for PubMedID 33026137

  • Peatland warming strongly increases fine-root growth PNAS Malhotra, A., Brice, D., Childs, J., Grahams, J., Hobbie, E., Vander Stel, H., Feron, S., Hanson, P., Iversen, C. 2020
  • Rapid Net Carbon Loss From A Whole-Ecosystem Warmed Peatland AGU Advances Hanson, P. J., Griffiths, N. A., Norby, R. J., Sebestyen, S. D., Phillips, J. R., Chanton, J. P., Kolka, R. K., Malhotra, A., Oleheiser, K. C., Warren, J. M., Shi, X., Yang, X., Mao, J., Ricciuto , D. 2020
  • Large loss of CO2 in winter observed across the northern permafrost region. Nature Climate Change Natali, S., et al 2019; 9: 852-857
  • 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

  • Reviews and syntheses: Changing ecosystem influences on soil thermal regimes in northern high-latitude permafrost regions BIOGEOSCIENCES Loranty, M. M., Abbott, B. W., Blok, D., Douglas, T. A., Epstein, H. E., Forbes, B. C., Jones, B. M., Kholodov, A. L., Kropp, H., Malhotra, A., Mamet, S. D., Myers-Smith, I. H., Natali, S. M., O'Donnell, J. A., Phoenix, G. K., Rocha, A. V., Sonnentag, O., Tape, K. D., Walker, D. A. 2018; 15 (17): 5287–5313
  • Post-thaw variability in litter decomposition best explained by microtopography at an ice-rich permafrost peatland ARCTIC ANTARCTIC AND ALPINE RESEARCH Malhotra, A., Moore, T. R., Limpens, J., Roulet, N. T. 2018; 50 (1)
  • The Fate of Root Carbon in Soil: Data and Model EOS Malhotra, A., Sihi, D., Iversen, C. 2018

    View details for DOI 10.1029/2018EO112593

  • 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

    Abstract

    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 PubMedID 28981192

  • Temporal and Spatial Variation in Peatland Carbon Cycling and Implications for Interpreting Responses of an Ecosystem-Scale Warming Experiment SOIL SCIENCE SOCIETY OF AMERICA JOURNAL Griffiths, N. A., Hanson, P. J., Ricciuto, D. M., Iversen, C. M., Jensen, A. M., Malhotra, A., McFarlane, K. J., Norby, R. J., Sargsyan, K., Sebestyen, S. D., Shi, X., Walker, A. P., Ward, E. J., Warren, J. M., Weston, D. J. 2017; 81 (6): 1668–88
  • Biophysical drivers of seasonal variability in Sphagnum gross primary production in a northern temperate bog JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES Walker, A. P., Carter, K. R., Gu, L., Hanson, P. J., Malhotra, A., Norby, R. J., Sebestyen, S. D., Wullschleger, S. D., Weston, D. J. 2017; 122 (5): 1078–97
  • A New Platform for Managing Soil Carbon and Soil Health EOS Loisel, J., Malhotra, A., Phillips, C. 2017

    View details for DOI 10.1029/2017EO080753

  • Ecohydrological feedbacks in peatlands: an empirical test of the relationship among vegetation, microtopography and water table ECOHYDROLOGY Malhotra, A., Roulet, N. T., Wilson, P., Giroux-Bougard, X., Harris, L. I. 2016; 9 (7): 1346–57

    View details for DOI 10.1002/eco.1731

    View details for Web of Science ID 000390021700016

  • Environmental correlates of peatland carbon fluxes in a thawing landscape: do transitional thaw stages matter? BIOGEOSCIENCES Malhotra, A., Roulet, N. T. 2015; 12 (10): 3119–30