EGU23-11005, updated on 26 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regional ecotypes structure biogeography of Amazon forest drought resilience and vulnerability

Shuli Chen1, Scott Stark2, Antonio Nobre3, Luz Cuartas4, Diogo Amore4, Natalia Restrepo-Coupe1, Marielle Smith2,5, Rutuja Chitra-Tarak6, Hongseok Ko1, Bruce Nelson7, and Scott Saleska1,8
Shuli Chen et al.
  • 1Department of Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
  • 2Department of Forestry, Michigan State University, East Lansing, MI 48824, USA
  • 3National Institute for Space Research (INPE), Avenida dos Astronautas, São José dos Campos, São Paulo 12201-1758 Brazil
  • 4Center for Monitoring and Early Warning of Natural Disasters (CEMADEN); São José dos Campos, São Paulo 12247-016, Brazil
  • 5School of Natural Sciences, College of Environmental Sciences and Engineering, Bangor University, Bangor LL57 2DG, United Kingdom
  • 6Los Alamos National Laboratory, Earth and Environmental Sciences, PO Box 1663, Los Alamos, NM 87545, USA
  • 7Brazil’s National Institute for Amazon Research (INPA), Manaus, Amazonas, Brazil
  • 8Department of Environmental Sciences, University of Arizona, Tucson, AZ 85721, USA

Amazonia contains the most extensive tropical forests on Earth, but the role of the region as a carbon appears to be declining. Increasing deforestation, fire and climate change-associated increases in drought, threaten to push forests past a tipping point. However, forests are complex, exhibiting drought responses indicative of both resilience (photosynthetic “greening”) and vulnerability (browning and tree mortality) that are difficult to explain by climate variation alone. Still needed is a framework for understanding and predicting how different regions will respond to different kinds of future drought. Here, we combine remotely-sensed photosynthetic vegetation indices (enhanced vegetation index, EVI, corrected for sun-sensor geometry; and solar-induced chlorophyll fluorescence, SIF) with ground-based tree demography to test recent ecological hypotheses about forest drought resilience and vulnerability for different forest ecotypes across the basin, defined by their water-table depth, soil fertility and vegetation characteristics. In high-fertility southern Amazonia, drought response was importantly structured by water-table depth, with resilient greening in shallow-water-table-forests (where greater water availability heightened responsiveness to excess sunlight) contrasting with vulnerability (“browning” and excess tree mortality) over deeper water tables. Notably, shallow-water-table-forest resilience weakened as droughts lengthened. By contrast, low-fertility northern Amazonia, with slower-growing but drought-hardy trees (or tall trees, with deep-rooted water access), supported more drought-resilient forests independent of water-table depth. This work reveals a new biogeography of forest drought response that provides a framework for conservation decisions and improved prediction of heterogeneous forest responses to future climate changes, but warns that longer/more frequent droughts undermine these multiple ecohydrological strategies of Amazon forest resilience.

How to cite: Chen, S., Stark, S., Nobre, A., Cuartas, L., Amore, D., Restrepo-Coupe, N., Smith, M., Chitra-Tarak, R., Ko, H., Nelson, B., and Saleska, S.: Regional ecotypes structure biogeography of Amazon forest drought resilience and vulnerability, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-11005,, 2023.