EGU21-15550
https://doi.org/10.5194/egusphere-egu21-15550
EGU General Assembly 2021
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Global sensitivities of forest carbon changes to environmental conditions 

Simon Besnard1,2, Maurizio Santoro4, Oliver Cartus4, Naixin Fan1, Nora Linscheid1, Richard Nair1, Ulrich Weber1, Sujan Koirala1, and Nuno Carvalhais1,3
Simon Besnard et al.
  • 1Max Planck Institute, Biogeochemistry, Germany (sbesnard@bgc-jena.mpg.de)
  • 2Laboratory of Geo-Information Science and Remote Sensing, Wageningen University & Research, The Netherlands
  • 3Departamento de Ciências e Engenharia do Ambiente, DCEA, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
  • 4Gamma Remote Sensing, 3073 Gümligen, Switzerland

Quantifying the responses of forest dynamics to fluctuations in the atmosphere, hydrosphere and land surface conditions at global scales have been rather challenging. Despite the understanding that favourable environmental conditions promote forest growth, the effects have been challenging to observe across different ecosystems and climate gradients. Based on a global annual time series of aboveground biomass (AGB) from 1992 to 2018, we present forest carbon changes and provide insights on the controls of atmospheric (e.g., climate), hydrosphere (e.g., soil water availability) and land surface (e.g., changes in forest cover) conditions on forest carbon changes from local to global scales. Our findings indicate a gradient of forest gains and losses across AGB classes, with regions with carbon stocks of 50-100 MgC ha-1 depicting both the highest forest gains and losses. Furthermore, we observe that changes in forest carbon stocks were systematically positively correlated with changes in forest cover, while it was not necessarily the case with other environmental variables, such as air temperature and water availability at the uni-variate level. We also used a gradient boosted decision tree model and a variable importance metric (i.e., SHAP values) to demonstrate that atmospheric conditions largely dictate forest carbon changes followed by land surface and hydrosphere conditions. Interestingly, the observed functional relationships indicate a strong sensitivity of forest carbon changes to recent-past carbon stocks and both recent-past and concurrent atmospheric water demand. Regionally, we find evidence that carbon gains from long-term forest growth covary with long-term carbon sink inferred from atmospheric inversions at the ecosystem level. Our study quantifies the contributions from the atmosphere, hydrosphere, and land surface conditions to forest carbon changes and provides new insights into the underlying mechanisms of forest growth on the global carbon cycle.

How to cite: Besnard, S., Santoro, M., Cartus, O., Fan, N., Linscheid, N., Nair, R., Weber, U., Koirala, S., and Carvalhais, N.: Global sensitivities of forest carbon changes to environmental conditions , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15550, https://doi.org/10.5194/egusphere-egu21-15550, 2021.

Displays

Display file