Tree-Ring Based Reconstruction of Drought over the Past 500-1000 Years in the Eastern United States

Columbia University, New York NY

Investigators

Abstract

This award will support research to reconstruct the drought history of the eastern United States over the last 500-1,000 years using the analysis of tree-rings from two species of long-lived conifers; the eastern red cedar (Juniperus virginiana) and the northern white cedar (Thuja occidentalis). This data will greatly improve estimates of the full range of drought variability across the United States. The widespread discovery of ancient forests of these tree species living or preserved on steep cliff faces in the northeast will enable the development of tree-ring chronologies covering the past 1,000 years from living trees and well-preserved fossil wood. Eastern red and northern white cedar may represent the only widely distributed species that are available for developing a network of such long drought-sensitive tree-ring chronologies in the eastern United States. The dendroclimatic potential of black gum (Nyssa sylvatica) growing in wetlands and swamps in the northeastern United States will also be examined. This is one of the longest-lived hardwoods in the world with a documented age of 500-700 years. Preliminary analyses indicate that this species produces cross-datable tree rings that correlate significantly with summer temperatures. A small network of black gum chronologies will be developed to determine the feasibility of using this species to reconstruct past summer temperatures in excess of 500 years before the present.