Climate–growth relationships of Schrenk spruce (Picea schrenkiana) along an altitudinal gradient in the western Tianshan mountains, northwest China

Abstract

The elevation-dependent tree growth patterns and climate–growth relationships were inferred from five tree-ring chronologies of Picea schrenkiana along an altitudinal gradient in the western Tianshan Mountains, northwest China. Schrenk spruce (Picea schrenkiana) is a crucial tree species in the western Tianshan Mountains of northwest China and plays a vital role in local ecosystems; it is of particular importance to assess the growth response of this species to climate in the context of global climate change. In this study, five tree-ring width chronologies of P. schrenkiana were developed along with an altitudinal gradient ranging from 1499 to 2820 m a.s.l. to investigate the radial growth variations and climate–growth relationships at different elevations. The statistical characteristics of tree-ring chronologies, combined with results of correlation matrix, and rotated principal component analysis, suggested that elevation played a crucial role in determining tree growth patterns in the study area. Correlation analyses of tree-ring chronologies with climate variables indicated that climate–growth relationships changed with increasing altitude. Tree growth at the low-elevation sites was primarily limited by moisture availability. With increasing altitude, the importance of precipitation decreased, tree growth at the high-elevation sites was mainly controlled by lower temperature. These results will help understand the growth response of P. schrenkiana to future climate change, and provide critical information for climate reconstructions using this tree species in the study area.