Understanding the Role of Typhoons, Fire, and Climate on the Vegetation Dynamics of Tropical Dry Forests: Looking to the Past to Develop Future Management Solutions
Final rept. Sep 2008-Jan 2010
WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
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Gaining an understanding of the range of environmental variability and the impacts on dry forest form and function is critical in order to effectively manage and restore these systems. An ideal approach to examine how ecosystems develop and respond to changing environmental conditions is to reconstruct the history of vegetation and environmental change using paleoecological proxies. The focus of this study was to examine the viability of developing coupled reconstructions of vegetation change, wildfires, and extreme typhoons over the last few millennia for the island of Guam. We collected a series of sediment cores from Cocos Lagoon on the south coast of Guam guided by geophysical surveys. More than forty coarse layers were deposited in the deepest portion of Cocos Lagoon over the last 2700 years. Cores from the Geus River delta provide a high-resolution record dating back more than 600 years of both marine and river sourced flooding. Pollen is well preserved in both the lagoon and delta sediments, though more abundant in the later. Fossil charcoal is also well preserved in the delta sediments providing an excellent proxy record of wildfires. Our results demonstrate that the sediments deposited in Cocos Lagoon over the past several millennia provide a unique opportunity to reconstruct detailed paleoecological and paleoclimatological data that can help improve our understanding of the complex interplay between climate, typhoon activity, fire, human land use, and dry tropical forest ecosystems.