Seminar: Should They Stay or Should They Go? The Responses of Tropical Trees and Tropical Forests to Global Warming

For tropical forests to survive anthropogenic global warming, the trees that comprise them will need to avoid rising temperatures through range shifts and “species migrations”, or they can stay and tolerate the newly emerging conditions through adaptation and/or acclimation. In this seminar I will show that while many tropical tree species are now shifting their distributions to higher, cooler elevations, the rates of these migrations are mostly insufficient to offset ongoing changes in temperatures, especially in lowland tropical rainforests where thermal gradients are shallow or nonexistent. Since the rapid pace and extreme severity of global warming also make it unlikely that tropical tree species can adapt (with some possible exceptions), I argue that the best hope for tropical tree species to avoid becoming “committed to extinction” is acclimation. While several new methods are being developed to test for acclimation, we unfortunately still do not know if tropical tree species can acclimate, or what factors may prevent or facilitate acclimation. Until these questions are answered, our ability to predict the fate of tropical trees and tropical forests – and the many services that they provide to humanity – remains critically impaired.