Code 614.3 Hydrological Sciences Branch Seminar

Dr. Scott R. Saleska, Assistant Professor, Ecology and Evolutionary Biology, Director, PIRE Program in Amazon-Climate Interactions, University of Arizona
Abstract Coupled climate-carbon cycle modeling studies indicate that Amazon forests are vulnerable to drought, and some predict substantial carbon loss from tropical ecosystems, including the drought-induced collapse of the Amazon forest and conversion to savanna, under future climate change. The model-simulated future forest collapse is attributable, in part, to a forest physiological feedback mechanism which should be observable as reductions in transpiration and photosynthesis during drought years under current climates. A widespread drought occurred in the Amazon in 2005, the first such climatic anomaly since the launch of the Terra satellite’s MODIS sensor in 1999, providing a unique opportunity to compare actual forest drought response to expectation on broad spatial scales. Contrary to expectation based on model simulations, satellite observations showed a large-scale green-up in intact evergreen forests of the Amazon in response to the 2005 drought. We explore the temporal dynamics of this response, and suggest that Amazon forests, though threatened by human-caused deforestation and fire, may be more resilient to climate changes than many ecosystem models assume. .