Across eastern North America, climate change is predicted to modify temperature, precipitation, and drought regimes. Dendroecology provides a useful framework for investigating how known climatic variation has impacted tree radial growth in the past, thus gaining insight into how climate may impact species growth and distribution in the future. Acer saccharum (Marsh.) (sugar maple) is a widespread and long-lived shade tolerant deciduous tree species common throughout eastern North America. A dendroecological study of Acer saccharum was conducted at five sites in Michigan, Indiana, Kentucky, and Missouri to: (1) determine correlations between radial growth and climate; (2) determine differences in growth-climate correlations along a latitudinal climate gradient; and (3) observe how growth-climate correlations may have changed over the last century. Tree cores were gathered, prepared, cross-dated, and measured via standard dendrochronological methods. Tree ring indices were constructed and correlated to monthly, seasonal, and annual climate using data from the National Climate Data Center.
Results/Conclusions
The strongest correlations between climate and Acer saccharum radial growth occurred during the June-August portion of the growing season. Positive correlations between radial growth and climate were found with precipitation and Palmer Drought Severity Index, while negative correlations were observed with temperature. A changing pattern in the strength of radial growth-climate correlations was not observed along latitudinal climate gradients, but correlations were stronger than previous studies located east of the Appalachian Mountains. Growth-climate correlations were observed decreasing over the last century at some sites and may be due to increases in growing season precipitation and a decline in frequent intense drought. A less stressful climate over the last century may be contributing to weakening growth-climate correlations, but this may change as climate models predict increased stressful conditions in the future. A more stressful climate for Acer saccharum may contribute to changes in forest compositions in eastern North America in the coming century as climate change may shift the competitive balance of overstory trees.