Abstract
Tropical forests are the most biodiverse terrestrial ecosystems on Earth and are essential in regulating global climate, yet they face myriad threats from anthropogenic disturbances. In this dissertation, I combine standardized botanical inventory methods and advanced statistical analyses to investigate how climate change and other disturbances influence tropical tree diversity, composition, and functional traits across multiple spatial and temporal scales.
First, using a network of permanent forest dynamics plots, I analyze differences in tree communities between disturbed and old-growth forests. I then examine long-term trait acclimation of individual tropical trees to climate change using historical and contemporary herbarium specimens. While trees are exhibiting some trait acclimation, leaf temperatures have increased rapidly through time, indicating that tropical trees may be reaching thermal thresholds and declines in performance. Next, I leverage a unique naturally heated forest along the Boiling River in the Peruvian Amazon, to assess the impacts of elevated temperatures on woody plant communities. Results show a significant decline in tree diversity and a shift towards more thermophilic species compositions, suggesting that future warming may drive biodiversity loss and biotic attrition in lowland Amazonian forests. Finally, I explore patterns of plant diversity and endemism on the Sierra Nevada de Santa Marta, Colombia, a mountain famed for its high levels of endemism. By compiling species occurrence records and conducting floristic comparisons with nearby mountain ranges, I identify 164 endemic plant species, highlight the mountain’s unique flora, and underscore the urgent need for conservation efforts and further botanical exploration.