NOAA/WDS Paleoclimatology - Maxwell - Howland Forest - TSCA - ITRDB ME044

Determining the response of forest growth and productivity to climate variability is crucial for understanding and modeling forest carbon sequestration in mesic temperate forests. Most tree-ring analyses have used monthly climate data. Daily climate data may be more appropriate to use in the determination of tree-ring response to climate because cell division, enlargement, and thickening occur during discrete periods of the growing season. We analyze annual tree-ring width and d13C from Tsuga canadensis (1992-2012) at ten sites in the northeastern US to test the null hypothesis that tree-ring width and d13C respond similarly to critical climate periods using daily climate data and linear regression. There was a significant difference in the climate response of ring width and d13C. Precipitation predicted both d13C and ring width with the highest r2 and greatest level of significance overall. d13C integrated climate over longer periods of the year (and previous year) than ring width at most sites. d13C showed a more consistent seasonal signal across sites for each climate variable than ring width. Our work provides a new perspective on the response of annual tree growth and d13C to climatic variability that can inform ecosystem productivity, carbon cycle, and earth system models.