Previous season climate controls the occurrence of black spruce growth anomalies in boreal forests of Eastern Canada

To better understand climatic origins of annual tree-growth anomalies in boreal forests, we analysed 895 black spruce (Picea mariana [Mill.] B.S.P.) tree-growth series from 46 xeric sites situated along three latitudinal transects in Eastern Canada. We identified inter-annual (based on comparison to previous year growth) and multi-decadal (based on the entire tree-ring width distribution) growth anomalies between 1901 and 2001 at site and transect levels. Growth anomalies occurred mainly at site level and seldom at larger spatial scales. Both positive inter-annual and multi-decadal growth anomalies were strongly associated with below-average temperatures and above-average precipitation during the previous growing season (Junet-1-Augustt-1). The climatic signature of negative inter-annual and multi-decadal growth anomalies was more complex and mainly associated with current year climatic anomalies. Between the early and late 20The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author