Timing of Tropical Vegetation Response Following Abrupt Deglacial Climate Changes

全球气候正在加速变化，社会决策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15，000至10，000年前最后一次冰消期气候突变后植被组合的响应时间和变化率。 年度层状沉积物是这一目的的理想选择，因为它们不受穴居生物的干扰，通常具有较高的积累率。 我们将在热带大西洋的两个地点从层状沉积物中构建陆地植被和气候变化的高分辨率记录。 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）来描述植被的特征，而过去气候变化的记录将通过对与河流径流有关的元素丰度的连续分析来构建。从相同的沉积物芯样中，在潮湿和干燥条件之间的快速气候转变过程中，植被和气候变化将具有可比性。该项目将提供最精确的措施，目前可获得的快速气候变化的植被组合的反应，并将解决几个悬而未决的问题：有多快冰川植被变化发生？在不同的气候变化速率之后，植被是否以相同的速率变化？植被变化相对于近源气候强迫的时间是什么？ 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善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.