Assessing the Effects of Human Activity on the Composition of Tropical Forests

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This project examines human impacts on rain forest ecosystems. Noted for their biodiversity, the botanical composition of rain forests has potentially been shaped during extended periods of human occupation by the planting, cutting, and burning of plants. An alternative possibility is that human activity affects the composition of rain forests on shorter time scales, including recent periods of intensive exploitation of forests for rubber and other products. This study examines these alternatives though a combination of research methods that includes the analysis of sediment cores from tropical lakes, documentation of vegetation in forested locations, and surveys of local residents to determine variation in the uses of local plants. This combination of methods facilitates analysis of change in forest composition over time, allowing the researchers to infer when changes occurred and the extent to which human activity resulted in current patterns. The researchers also collaborate with local ecotourism organizations to promote greater awareness of human impacts on forested environments. The project also contributes to the mentorship and training of multiple students in ecological field methods and data analysis.The extent to which human activity has modified tropical rain forests has been a longstanding question among geographers. To make inferences about human impacts on forests, the researchers examine lake sediments, which accumulate over thousands of years. The analysis of pollens and plant parts that have fossilized in these sediments provides insights into fluctuations in botanical diversity over time. The researchers combine these findings with data on local ethnobiological knowledge, which permits retrospective insights into the ways that past human inhabitants may have curated the forest in beneficial ways. The historical trajectory of tropical forests is relevant to climate projections given evidence that newer forests absorb atmospheric carbon at relatively greater rates. Ascertaining the extent to which forests have been modified on different timescales also provides insights into the resilience of forests to human activity, including present impacts on the ecosystems. The project also contributes to conservation in tropical settings via partnerships with ecotourism organizations that support conservation efforts. The training of graduate and undergraduate students contributes to the goals of broadening participation in scientific research.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.