Radial growth response of white oak to climate in eastern North America

Predicting forest responses to climate change requires an understanding of the cause–effect relationships linking climate to tree growth. Dendroecological analyses across sites that span climate gradients provide one means of characterizing such relationships. Dendroecological analyses for white oak ( Quercus alba L.) at 149 sites spanning the species range in eastern North America identified spatially replicated growth–climate associations. Early growing season site water balance variables for the year of annual ring formation had the strongest, most spatially replicated associations with growth. There was little evidence of phenological variation of these associations related to the latitudinal temperature gradient. Most spatial variation in growth–climate associations was along an east-to-west precipitation gradient. Radial growth was most strongly correlated with site water balance at sites in the northwest quadrant of the range, characterized by continental climate and high interannual variability in precipitation. There was little evidence that dormant season temperature affects white oak growth, even at the northern range limit. Correlations with dormant season precipitation were common in the northwest part of the range, where winter soil water recharge may be more variable. Spatial replication was a useful criterion for distinguishing growth–climate correlations that reflect cause–effect relationships.