A dendroecological comparison of drought sensitivity between white spruce stands in northern New Brunswick

Abstract

White spruce is an important tree species to Atlantic Canada’s forestry industry, and its reported high sensitivity to drought raises significant concerns for wood supply in the region. In this study, we take advantage of the recent drought that occurred during 2017-2021, to assess variations in drought sensitivity with a dendrochronology approach across 32 planted white spruce stands in an intensively managed landscape of northern New Brunswick. The analysis of long-term climate-growth coupling over the 1978-2023 period revealed a general trend for reduced growth during hot, dry summers. In line with this finding, we observed growth reductions up to 75% during the studied drought period. Linear mixed-effect regression models showed that these growth declines were proportional to tree size, while individual tree competition had no significant effect. With the intensive competition management already applied in the region, our results suggest that additional thinning will not reduce future drought stress.