Spatial analysis of black spruce (Picea mariana (Mill.) B.S.P.) radial growth response to climate in northern Québec – Labrador Peninsula, Canada

Abstract

The aim of this study is to analyze the relationships between black spruce (Picea mariana (Mill.) B.S.P.) growth and climate at a large spatial scale in North America’s northeastern boreal forest. The study area (approximately 700 000 km2) is located in the taiga zone of the Quebec – Labrador Peninsula. A network of tree-ring chronologies from 93 black spruce populations was developed. A hierarchical cluster analysis was conducted to analyze tree-ring series affinities, and response functions were calculated to analyze relationships between tree rings and climate. The cluster analysis results showed well-marked spatial affinities among the tree-ring series. These affinities were strongly linked with the spatial variability of the relationships between tree rings and climate. The interannual growth variations were governed mainly by the temperature variables that preceded the growing season (November (negative influence), December–January (positive influence), and April (positive influence)). The growing-season temperature (July temperature) mainly influenced the northernmost populations. Relationships between tree rings and climate in the northeastern boreal forest varied at a large spatial scale. This variability was expressed by a north–south contrast, which appears to be related to a temperature gradient, and an east–west contrast linked to a humidity gradient, which favors winter snow cover.