Natan Holtzman is a fourth-year PhD student in the Earth System Science department working with Prof. Alexandra Konings. He uses remote sensing and modeling to study how water moves between the atmosphere, plants, and soil. Natan graduated from the University of North Carolina at Chapel Hill in 2016 with a B.S. with honors in Geological Sciences and minors in Mathematics and Biology.
- Bias Correction of Hydrologic Projections Strongly Impacts Inferred Climate Vulnerabilities in Institutionally Complex Water Systems JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT 2022; 148 (1)
Detecting Forest Response to Droughts with Global Observations of Vegetation Water Content.
Global change biology
Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analogue of the pressure-volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions - which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.
View details for DOI 10.1111/gcb.15872
View details for PubMedID 34478589
- Interannual Variations of Vegetation Optical Depth are Due to Both Water Stress and Biomass Changes GEOPHYSICAL RESEARCH LETTERS 2021; 48 (16)
- Global ecosystem-scale plant hydraulic traits retrieved using model-data fusion HYDROLOGY AND EARTH SYSTEM SCIENCES 2021; 25 (5): 2399-2417
- L-band vegetation optical depth as an indicator of plant water potential in a temperate deciduous forest stand BIOGEOSCIENCES 2021; 18 (2): 739-753
- SMAP Detects Soil Moisture Under Temperate Forest Canopies GEOPHYSICAL RESEARCH LETTERS 2020; 47 (19)
- SMAP VALIDATION EXPERIMENT 2019-2021 (SMAPVEX19-21): DETECTION OF SOIL MOISTURE UNDER FOREST CANOPY IEEE. 2020: 3338-3340