EAR-PF: Plant Wax Transport and Integration Through the Late Holocene in Guatemala

Parker, Wesley George, Cincinnati OH

Investigators

Abstract

Dr. Wesley Parker has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans under the mentorship of Dr. Peter Douglas at McGill University. The rainforests of Central America are being lost at an alarming rate, and this has significant impacts on regional precipitation, natural resource availability, and the global carbon cycle. These environmental changes are expected to continue in the future, adversely impacting both human and ecological communities across Central America. Therefore, investigation of changing vegetation and precipitation regimes will complement and expand knowledge surrounding natural variability in tropical forests and constrain the impacts of human activities on these endangered forests. The proposed research will analyze modern plant waxes (abundant and long-lasting hydrocarbon molecules) preserved in sediment cores from lake basins in Guatemala to investigate geospatial transport and integration of plant waxes in the modern tropical forests of Central America. The results will establish a 9,000 year profile of carbon and hydrogen isotope variability that will develop knowledge surrounding long-term changes in vegetation and precipitation. This hypothesis driven research will test the ideas that changing vegetation types in Central America can be assessed through plant wax analysis, and that plant waxes will accurately track climate perturbations in the Western Hemisphere. This project will be conducted in collaboration with local conservation groups in Guatemala to help inform their activities and will be coupled with community education programs in the USA, Canada, and Guatemala. The research is accomplished in two phases. First, the hydrogen and carbon isotopes in long-chained plant waxes (n-alkyl lipids) from modern leaf material and sediments are analyzed using compound specific isotope analyses to characterize plant wax transportation pathways and vegetation balance (C3/C4 plant ratio) in the Lake Izabal and Petén Basins of Guatemala. Then, plant waxes retrieved from sediment cores covering 9,000 years are analyzed to reconstruct changes in vegetation and precipitation through the middle and late Holocene in both basins. These plant wax-derived isotope profiles are then compared to independent proxy data to identify signals of known Holocene climate events (e.g. 8.2 kyr event) and track the magnitude of these signals in tropical Central America. This research enhances the overall quality and applicability of ongoing paleoclimatic research in Central America by generating the first middle and late Holocene hydrogen and carbon isotope profiles for the focal basins. This research can inform policymakers responsible for the generation and implementation of regional conservation and climate adaptation strategies that will benefit human populations, ecological systems, and financial investments in Central America. Additional broader impacts of this research include outreach educational activities in the USA, Canada, and Guatemala. This project received co-funding from the Earth Science section of the Paleo Perspectives on Climate Change program. 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.