Holocene Climate and Environmental History in the Northeastern Caribbean

对淡水湖泊中作为沉积物保存下来的物质的分析是对世界范围内气候和环境历史的科学认识的基础。 对伊斯帕尼奥拉岛湖泊沉积物岩芯的研究将大大加强热带大西洋地区的陆地记录。 伊斯帕尼奥拉岛为分析热带环流模式的全新世变化提供了一个独特的实验室，因为它的山地地形和山脉的西北-东南方向联合收割机结合在一起，产生了降水由不同水分来源主导的地区（例如，信风; ITCZ相关降水;与极地爆发相关的锋面）。 研究人员将检查花粉，木炭，硅藻，稳定同位素和C/N比在湖泊沉积物芯在前三个领域的季节。 这些岩芯的年代跨度从过去的两千年到七千年，它们来自两个现代植被和气候截然不同的地区：位于多米尼加共和国中部科迪勒拉山脉西南侧的中海拔地区拉斯拉古纳斯和西北低地的拉古纳萨拉迪利亚。 在这些地区的不同降水控制将允许植被和水文变化的代理记录的发展，反映了历史的向北延伸的ITCZ相关的降水（拉斯Lagunas）和历史的极地爆发相关的降水（萨拉迪利亚）。 在这样做的新记录将揭示潜在的机制以及环加勒比地区过去气候变化/事件的模式，包括在约2400 cal yr BP和约1200 cal yr BP可能对史前文化产生重大影响的干旱。 这项研究还将增加对史前人类对伊斯帕尼奥拉岛景观，全新世植被和火灾动力学影响的了解，并将为解释伊斯帕尼奥拉岛和其他地方以前的记录提供新的背景。热带地区对我们理解全球变化，过去和未来至关重要。 这项研究的目的是增加我们对新热带气候的两个重要方面的全新世历史的理解：北半球夏季ITCZ平均纬度在大西洋的迁移，以及极地爆发的热带影响。 努力开发和解释这些记录可以提供洞察未来可能发生的热带气候变化，以及它们的非热带后果。 该项目对栖息地的保护、管理和恢复也具有重要意义。 在这个项目中进行的研究将为一些研究生和本科生提供教育机会。 研究成果和全球变化的科学知识将通过“访问科学家”计划分享，PI和学生将在当地学校与田纳西州地理联盟合作开发。

Analysis of materials preserved as sediments in freshwater lakes underlies much of the scientific understanding of climate and environmental history world-wide. This study of lake-sediment cores from the island of Hispaniola will significantly strengthen terrestrial records from the tropical Atlantic region. Hispaniola provides a unique laboratory for analyzing Holocene changes in tropical circulation patterns because its mountainous terrain and the WNW-ESE orientation of its mountain ranges combine to produce areas in which precipitation is dominated by different moisture sources (e.g., trade winds; ITCZ-related precipitation; fronts associated with polar outbreaks). The investigators will examine pollen, charcoal, diatoms, stable isotopes, and C/N ratios in lake sediment cores obtained in three previous field seasons. The cores, which span the last two to seven millennia, are from two contrasting areas of modern vegetation and climate: Las Lagunas, a mid-elevation site on the southwestern flank of the Dominican Republic's Cordillera Central, and Laguna Saladilla in the northwestern lowlands. The different precipitation controls in these areas will allow the development of proxy records of vegetation and hydrological changes that reflect the history of northward extent of ITCZ-related precipitation (Las Lagunas) and the history of polar outbreak related precipitation (Saladilla). In doing so the new records will shed light on potential mechanisms as well as patterns of past climate shifts/events in the circum-Caribbean, including droughts at ~2400 cal yr BP and ~1200 cal yr BP that may have had significant impacts on prehistoric cultures. The study will also increase understanding of prehistoric human impacts on Hispaniolan landscapes, and on Holocene vegetation and fire dynamics, and will provide new context for interpreting previous records from Hispaniola and elsewhere. The tropics are crucial to our understanding of global change, past and future. This research is designed to increase our understanding of the Holocene histories of two important aspects of neotropical climate: migration of mean boreal summer ITCZ latitude in the Atlantic, and tropical influence of polar outbreaks. Efforts to develop and interpret these records can provide insight on possible future shifts in tropical climate, and their extratropical consequences. This project will also have significance for habitat conservation, management, and restoration. The research undertaken in this project will provide educational opportunities for several graduate and undergraduate students. Research results and scientific knowledge of global change will be shared through a "Visiting Scientist" program that the PIs and students will develop in local schools in collaboration with the Tennessee Geographic Alliance.