9307055 Jackson The central objective of this project is to improve understanding of the vegetation-sensing properties of sedimentary pollen assemblages, which are the primary source of information on past vegetation in most of the world. The research is specifically concerned with determining the effective pollen source areas for important tree taxa, and understanding the factors that govern them. These factors include basin size, canopy cover, physical properties of pollen dispersal, and the patterning of vegetation on the landscape. A related objective is to determine how these factors influence pollen representation in percentage data, and to refine and test calibrations aimed at correcting for those effects. Modern pollen assemblages from forest floor moss polsters at 130 sites in northern New York and southern New England, and 25 sites in northern Arizona, will be compared with vegetation composition and patterns across a range of spatial scales. Scatter plots and regression analysis will be used to identify pollen source areas and to estimate and test calibration parameters for relating pollen percentages to forest composition. %%% An understanding of these factors is crucial to the design and interpretation of paleoecological studies, because pollen source areas determine the spatial scales at which pollen assemblages record information about vegetation. Analyses of historical vegetation patterns are essential for understanding large- scale vegetation response to climate change. ***
