Collaborative Research: A longitudinal study to test for the acclimation of individual trees to 4+ decades of climate change, and the consequences for tropical rainforests

This project aims to improve our understanding of how Amazonian tree species are, or are not, acclimating to climate change, and the consequences for species performance and tropical forest dynamics. Understanding the capacity for tropical trees to respond to rising temperatures will increase knowledge of how environmental change affects rainforest species and will provide valuable information that can inform predictions and management strategies. In this project, researchers will compare key functional and morphological traits on leaf samples collected from the same individual trees of numerous tree species over multiple decades. If acclimation is occurring, researchers expect to find that trees shift their leaf traits to offset the effects of climate change. This will be one of the first multi-decadal studies of leaf functional traits measured on individual tropical trees, thus filling an important gap in knowledge about the ability of long-lived trees to respond to climate change, as well as the consequences of acclimation for forest function and structure. The results of this research will be integrated into diverse environmental education and training initiatives to increase public awareness about the ecology and conservation of tropical forests. Researchers will census four 1-ha forest inventory plots in the Tambopata region of southeastern Peru to assess the extent of acclimation of diverse forest tree species. By comparing census data with herbarium specimens of ~15 abundant focal tree species collected in the 1980-1990s, the team has a unique opportunity to quantify changes across decades. For each living source tree of these focal species, researchers will collect multiple samples of young and mature sun and shade leaves to create new herbarium specimens. Researchers will then measure a suite of functional and morphological traits on both the new and historical herbarium specimens of each focal tree. To better assess inter-tree variability and control for trait vs. tree size relationships, researchers will collect additional samples and measure functional traits on all other individual trees of the focal species that they find growing in or near the Tambopata census plots. Finally, researchers will also measure the same suite of morphological traits on all available herbarium collections of the focal species from the study region (southwest Amazon) over the past century in order to assess how these traits vary spatially and temporally. Using the collected data, researchers will analyze the relationships between climate and functional traits and test if acclimation is related to individual and population-level responses such as diameter growth, survival, and changes in relative abundance within communities. The results of this research will be used to create teaching materials and active education activities for k-12 students and will form the foundation for new teaching exercises at the university level. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.