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

Wesley Parker博士获得美国国家科学基金会EAR博士后奖学金，在麦吉尔大学Peter Douglas博士的指导下进行研究和教育计划。中美洲的雨林正在以惊人的速度消失，这对区域降水、自然资源可用性和全球碳循环产生了重大影响。预计这些环境变化将在未来继续，对整个中美洲的人类和生态社区产生不利影响。因此，对变化的植被和降水制度的调查将补充和扩大对热带森林自然变率的认识，并限制人类活动对这些濒危森林的影响。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（丰富且持久的碳氢化合物分子），以研究中美洲现代热带森林中植物蜡的地理空间运输和整合。研究结果将建立一个9000年的碳和氢同位素变化概况，这将发展有关植被和降水长期变化的知识。这项假设驱动的研究将验证这样的观点，即中美洲不断变化的植被类型可以通过植物蜡分析来评估，而植物蜡将准确地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，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项目相结合。本研究分两个阶段完成。首先，利用复合比同位素分析方法，分析了危地马拉伊扎巴尔湖和petsamin盆地现代叶片物质和沉积物中长链植物蜡（n-烷基脂）的氢和碳同位素特征，以表征植物蜡的运输途径和植被平衡（C3/C4植物比）。然后，对覆盖9000年的沉积物岩心植物蜡进行分析，重建了两个盆地在全新世中晚期的植被和降水变化。然后将这些植物蜡衍生的同位素剖面与独立的代理数据进行比较，以确定已知的全新世气候事件（例如8.2 kyr事件）的信号，并跟踪这些信号在中美洲热带地区的强度。本研究通过生成首个全新世中晚全新世焦点盆地氢碳同位素剖面，提高了正在进行的中美洲古气候研究的整体质量和适用性。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决策者提供信息，这些战略将有利于中美洲的人口、生态系统和金融投资。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。该项目获得了气候变化古视角项目地球科学部分的共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.