Experimental evidence of climate change extinction risk in tropical plants.

Abstract Climate change is conjectured to endanger tropical species, particularly in biodiverse montane regions, but accurate estimates of extinction risk are limited by a lack of empirical data describing tropical species’ sensitivity to climate. To fill this gap, studies must match high-quality distribution data with multi-year, transplant experiments. Here, we conducted field surveys of epiphyte distributions on three mountains in Central America and performed reciprocal transplant experiments on one mountain across sites that varied in elevation, temperature and aridity. We find that most species are unable to survive outside of their narrow elevational distributions. Additionally, our findings suggest starkly different outcomes by 2100 under different emission and temperature change scenarios. Under low-emission scenarios, most tropical montane species will survive, but under mid or high-emission scenarios a minimum of 5–36% of our study species may go extinct and 10–50% of populations may be lost. This result demonstrates that current actions towards climate mitigation and emissions reduction may significantly impact the number of tropical extinctions that will occur due to climate change. Unique in its precise test of tropical species’ climate tolerances in a large field experiment, our work corroborates earlier conjecture about wide-spread extinctions from climate change in tropical montane ecosystems.