EGU21-1783
https://doi.org/10.5194/egusphere-egu21-1783
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Changing sensitivity of global vegetation productivity to hydro-climate drivers

Wantong Li1, Matthias Forkel2, Mirco Migliavacca1, Markus Reichstein1, Sophia Walther1, Jasper Denissen1,3, and René Orth1
Wantong Li et al.
  • 1Department of Biogeochemical Integration, Max Planck Institute for Biogeochemistry, D-07745 Jena, Germany (wantong@bgc-jena.mpg.de)
  • 2Technische Universität Dresden, Institute of Photogrammetry and Remote Sensing, Helmholtzstr. 10, D-01069 Dresden, Germany
  • 3Hydrology and Quantitative Water Management Group, Wageningen University, Wageningen, Netherlands

Terrestrial vegetation couples the global water, energy and carbon exchange between the atmosphere and the land surface. Thereby, vegetation productivity is determined by a multitude of energy- and water-related variables. While the emergent sensitivity of productivity to these variables has been inferred from Earth observations, its temporal evolution during the last decades is unclear, as well as potential changes in response to trends in hydro-climatic conditions. In this study, we analyze the changing sensitivity of global vegetation productivity to hydro-climate conditions by using satellite-observed vegetation indices (i.e. NDVI) at the monthly timescale from 1982–2015. Further, we repeat the analysis with simulated leaf area index and gross primary productivity from the TRENDY vegetation models, and contrast the findings with the observation-based results. We train a random forest model to predict anomalies of productivity from a comprehensive set of hydro-meteorological variables (temperature, solar radiation, vapor pressure deficit, surface and root-zone soil moisture and precipitation), and to infer the sensitivity to each of these variables. By training models from temporal independent subsets of the data we detect the evolution of sensitivity across time. Results based on observations show that vegetation sensitivity to energy- and water-related variables has significantly changed in many regions across the globe. In particular we find decreased (increased) sensitivity to temperature in very warm (cold) regions. Thereby, the magnitude of the sensitivity tends to differ between the early and late growing seasons. Likewise, we find changing sensitivity to root-zone soil moisture with increases predominantly in the early growing season and decreases in the late growing season. For better understanding the mechanisms behind the sensitivity changes, we analyse land-cover changes, hydro-climatic trends, and abrupt disturbances (e.g. drought, heatwave events or fires could result in breaking points of sensitivity evolution in the local interpretation). In summary, this study sheds light on how and where vegetation productivity changes its response to the drivers under climate change, which can help to understand possibly resulting changes in spatial and temporal patterns of land carbon uptake.

How to cite: Li, W., Forkel, M., Migliavacca, M., Reichstein, M., Walther, S., Denissen, J., and Orth, R.: Changing sensitivity of global vegetation productivity to hydro-climate drivers, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1783, https://doi.org/10.5194/egusphere-egu21-1783, 2021.

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