Collaborative Research: Long-Term Dynamics of Caribbean Maritime Forest Ecosystems in the Context of Major Disturbance Events: The Role of Hurricanes and Fires

国家科学基础BCS-0964138，BCS-0964043丽莎·M·肯尼迪，刘锦标，路易斯安那州立大学弗吉尼亚理工学院关于飓风生态影响的文献很多，但几乎所有的研究都集中在相对短期的(年)变化上。其中许多研究提出的一个长期问题是，飓风是否会从长期(几十年到几个世纪)改变森林组成。此外，飓风过后，美国东南部的亚热带海洋森林的火灾危险增加，但这种关系是否适用于热带森林仍是一个问号。最近的进展使得能够在沉积物剖面中识别飓风登陆的替代记录，这为解决这些问题提供了机会。该项目将通过对多米尼加共和国沿海湖泊的沉积物记录进行古生态分析，研究飓风对热带森林的长期(数十年至数百年)影响，以及飓风与火灾之间可能存在的联系。调查人员将分析沉积物中包含的地质、地球化学和生物指标，并使用放射性碳测年，以确定飓风登陆的记录，并检查这些登陆如何影响植被组成，并在很长一段时间内与火灾相互作用。这项研究的一个关键目标是通过研究飓风溢流沉积物上方和下方紧密排列的样品中的花粉颗粒和微观木炭，记录飓风袭击后热带生态系统的植被变化是否长期存在，以及飓风袭击后热带生态系统的火灾危险是否增加(即飓风与火灾相互作用的假说)。在飓风登陆频率相对较高的多米尼加共和国的多个研究地点，将可以比较飓风对热带干燥和潮湿森林生态系统中植被和火灾的影响。对湖泊沉积物中现代花粉雨和历史飓风袭击特征的研究将为利用沉积替代数据解释古环境变化和事件提供基础。与中高纬度地区相比，热带地区的气候和植被动力学了解较少。该项目将制作多米尼加共和国古飓风活动的替代记录，该地区位于加勒比地区，对评估千年时间尺度上影响飓风活动的机制具有重要意义。这项研究的结果将揭示气候和环境历史的其他方面，可能包括哥伦布之前的人类活动，并将有助于更广泛地了解加勒比地区的环境变化，那里的长期历史仍然没有得到很好的记录。这项研究将提供一个长期的视角，并首次对多米尼加共和国的飓风重现期和登陆概率进行基于代理的估计，这可能对决策者在灾害规划和管理方面有用。该项目将为研究生和本科生提供参与国际研究的机会，包括实地和实验室部分。

NATIONAL SCIENCE FOUNDATIONABSTRACTBCS-0964138, BCS-0964043Lisa M. Kennedy, Kam-biu LiuVirginia Tech, Louisiana State UniversityThe body of literature on the ecological impacts of hurricanes is large, but nearly all the studies have focused on relatively short-term (years) changes. A persistent question arising from many of these studies is whether hurricanes change forest composition over the long term (decades to centuries). In addition, increased post-hurricane fire hazards have been hypothesized for the subtropical maritime forests of the southeastern U.S., but whether this relationship holds for tropical forests is still a question mark. Recent advances allowing identification of proxy records of hurricane landfalls in sediment profiles provide an opportunity to address such questions. This project will examine the long-term (decades to centuries) impacts of hurricanes on tropical forests and the possible link between hurricanes and fire through paleoecological analyses of sediment records from coastal lakes in the Dominican Republic. The investigators will analyze geological, geochemical, and biological proxies contained in the sediments, and use radiocarbon dating, to identify records of hurricane landfalls and to examine how these landfalls influence vegetation composition and interact with fire over long time scales. A key objective of this research is to document whether post-hurricane vegetation changes persist over the long term and whether fire hazards increase in tropical ecosystems after hurricane strikes (i.e., the hypothesis of hurricane-fire interactions) through the study of pollen grains and microscopic charcoal in closely spaced samples above and below hurricane overwash deposits. Multiple study sites in the Dominican Republic, where there are relatively high frequencies of hurricane landfalls, will allow comparisons between hurricane effects on vegetation and fire in tropical dry and moist forest ecosystems. The study of modern pollen rain and the signatures of historical hurricane strikes in lake sediments will provide a basis for interpreting paleoenvironmental changes and events from sedimentary proxy data.Climate and vegetation dynamics are poorly understood in tropical areas in comparison to mid- and high-latitude areas. This project will produce proxy records of paleohurricane activity from the Dominican Republic, a location in the Caribbean region strategic for evaluating mechanisms affecting hurricane activity on millennial timescales. The results of this study will shed light on other aspects of climate and environmental history, including possibly pre-Columbian human activities, and will help to provide a broader understanding of environmental change in the Caribbean, where long-term history is still poorly documented. This research will provide a long-term perspective and generate the first proxy-based estimates of hurricane return periods and landfall probabilities for the Dominican Republic, which may be useful to decision makers in terms of disaster planning and management. This project will provide opportunities for graduate and undergraduate students to participate in international research with field and laboratory components.