Red Spruce Tree-Ring Widths and Densities in Eastern North America as Indicators of Past Climate

Abstract

Dendroclimatological studies in eastern North America are enhanced by the use of long-time series of maximum latewood densities determined by x-ray densitometry. The densities show higher correlation from tree to tree and site to site than do ring-width measurements from the same trees. Based on the macroclimatic link thus implied, maximum density and width series of Picea rubens Sarg. from high elevations in Maine are used to reconstruct up to 310 yr of past spring temperatures at nearby climate stations. The regression equations explain from 33 to 47% of calibrated variance, and verification testing of the reconstructions produces highly significant correlations and high, positive reduction of error statistics. The climate-wood density relationships are considered in light of tree physiological factors that may explain them. Results from this study are applicable to (1) an increased understanding of the relationship of climate to the formation of wood density and (2) further development of paleoclimatological and paleoenvironmental studies via tree rings in mesic regions such as northeastern North America.