Tropical ecosystems responses to drought-fire interactions: tree mortality, ecosystem functioning and restoration success

Abstract

Climate change is expected to accelerate the intensity and frequency of natural and anthropogenic disturbances. In response, tropical ecosystems will likely experience tree mortality events, changes in competition for resources, and degradation of ecosystem processes and functioning. Identifying tree species with traits that confer greater resilience to novel disturbance regimes and climate envelopes is key to guide successful restoration efforts in the near future. The proposed study addresses three fundamental knowledge gaps that have precluded a better understanding of the vulnerability of tropical ecosystems (evergreen tropical forests, transitional between Amazonia and Cerrado and savannas) to climate change and anthropogenic disturbances: (1) How does the variability in tree height, bark thickness/growth and crown architecture across the Amazon and transitional ecosystems influence drought- and fire-induced tree mortality? (2) How fast do drought- and fire-disturbed forests recover their structure, functional and species diversity? and (3) can we increase the drought-fire resilience of forests and savannas? We will engage in a suite of field studies to address these questions. The results will greatly improve our ability to: (a) determine the vulnerability and predict the drought and fire-induced tree mortality in tropical ecosystems - a process lacking or grossly simplified in many earth system models; (b) quantify the capacity of severely disturbed forests to recover forest structure, diversity and functioning after degradation events; and (c) use the functional space of communities and the water safety margin of species as tools to develop more effective ecological restoration programs.