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.
