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

韦斯利·帕克博士获得了NSF EAR博士后奖学金，在麦吉尔大学彼得·道格拉斯博士的指导下开展研究和教育计划。中美洲的热带雨林正在以惊人的速度消失，这对区域降水、自然资源的可获得性和全球碳循环产生了重大影响。这些环境变化预计将在未来继续下去，对整个中美洲的人类和生态社区都产生不利影响。因此，调查不断变化的植被和降水状况将补充和扩大有关热带森林自然变异性的知识，并限制人类活动对这些濒危森林的影响。这项拟议的研究将分析保存在危地马拉湖盆沉积物岩心中的现代植物蜡质(丰富和持久的碳氢化合物分子)，以调查中美洲现代热带森林中植物蜡质的地理空间运输和整合。这些结果将建立一个9000年来碳和氢同位素变化的概况，这将发展关于植被和降水长期变化的知识。这项假设驱动的研究将检验这样的想法，即可以通过植物蜡分析来评估中美洲植被类型的变化，以及植物蜡将准确跟踪西半球的气候扰动。该项目将与危地马拉当地的保护组织合作进行，以帮助为他们的活动提供信息，并将与美国、加拿大和危地马拉的社区教育计划相结合。研究分两个阶段完成。首先，利用复合特定同位素分析方法，分析了现代叶材料和沉积物中长链植物蜡(正构烷基脂)中的氢和碳同位素，以表征危地马拉伊萨巴湖和佩廷盆地的植物蜡运输途径和植被平衡(C3/C4植物比)。然后，分析了从9000年来的沉积岩芯中提取的植物蜡质，以重建两个盆地在全新世中期和晚期的植被和降水变化。然后，将这些植物蜡提取的同位素剖面与独立的替代数据进行比较，以识别已知的全新世气候事件(例如8.2 KYR事件)的信号，并跟踪热带中美洲这些信号的强度。这项研究提高了中美洲正在进行的古气候研究的整体质量和适用性，为重点盆地生成了第一个全新世中期和晚期的氢和碳同位素剖面。这项研究可以为负责制定和实施区域保护和气候适应战略的政策制定者提供信息，这些战略将使中美洲的人口、生态系统和金融投资受益。这项研究的其他更广泛的影响包括在美国、加拿大和危地马拉的外展教育活动。这个项目得到了古气候变化展望计划地球科学部分的共同资助。这个奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.