Timing of Tropical Vegetation Response Following Abrupt Deglacial Climate Changes

全球气候正在加速变化，社会上的政策制定者必须准确预测自然生态系统的反应，以便预测和减轻最严重的环境影响。通过这项研究，我们将测量1.5万至1万年前最后一次冰川消融期间气候突变后植被组合的响应时间和变化率。年积层沉积物是理想的，因为它们不受穴居生物的干扰，通常具有较高的积累速率。我们将从热带大西洋两个地点的层状沉积物中构建陆地植被和气候变化的高分辨率记录。植被将使用可追溯到陆生维管植物来源的有机化合物（生物标志物）来表征，而过去气候变化的记录将通过与河流径流相关的元素丰度的连续分析来构建。植被和气候变化将在同一沉积物岩心的干湿条件之间的快速气候变化中具有可比性。该项目将提供目前可获得的植被组合对快速气候变化的反应的最精确测量，并将解决几个悬而未决的问题：冰川消融的植被转移发生得有多快？随着气候变化的速率不同，植被的变化速率是否相同？相对于最近的气候强迫，植被变化的时间是什么？通过帮助量化植被组合和整个生态系统对快速气候变化的敏感性，这项工作可能有助于改进对未来类似变化的预测。

Global climate is changing at an accelerating pace, and policy makers in society must have accurate predictions of the natural ecosystem response in order to anticipate and mitigate the most severe environmental impacts. With this research, we will measure the response times and rates of change in vegetation assemblages following abrupt climate shifts of the last deglaciation, 15,000 to 10,000 years ago. Annually laminated sediments are ideal for this purpose because they are undisturbed by burrowing organisms and typically have high accumulation rates. We will construct high-resolution records of both terrestrial vegetation and climate change from laminated sediments at two locations in the tropical Atlantic. Vegetation will be characterized using organic compounds (biomarkers) that can be traced back to terrestrial vascular plant sources, whereas records of past climate change will be constructed through continuous analysis of elemental abundances related to river runoff. Vegetation and climate shifts will be comparable across rapid climate transitions between wet and dry conditions from the same sediment cores. This project will provide the most precise measures currently obtainable of the response of vegetation assemblages to rapid climate change, and will address several outstanding questions: How quickly did deglacial vegetation shifts take place? Did vegetation change at the same rate following different rates of climatic change? What was the timing of vegetation change relative to the proximate climate forcing? By helping quantify the sensitivity of vegetation assemblages and entire ecosystems to rapid climate shifts, this work may allow improved prediction of similar changes in the future.