DROUGHT IN TROPICAL FORESTS: Linking mechanisms of drought sensitivity with plant dynamics and distributions
P 2.1 in Biodiversity and Nature Protection
Shifts in rainfall patterns together with an increase in the frequency of El Niño events are expected for the tropics, and these may have profound impacts on forest composition, structure and ecosystem function. Correlative approaches have been taken to extrapolate consequences of global climate change on tropical forest communities. However, sound predictions rely on an understanding of the mechanisms underlying species distributions, because many areas will experience novel climates. By combining extensive experimental data on species responses to drought, evaluations of mechanisms of drought resistance, and quantitative assessments of species occurrence across the pronounced rainfall gradient at the Isthmus of Panama, we show that species’ differential drought sensitivity shapes population dynamics and plant distributions in tropical forests at both local and regional scales. Our results suggest that niche differentiation with respect to soil water availability is a direct determinant of both local and regional scale distributions of tropical trees. Changes in soil moisture availability caused by global climate change are therefore likely to alter tropical species distributions, community composition and diversity.