Minimum temperature during the growing season limits the radial growth of timberline Schrenk spruce (P. schrenkiana)

Abstract

Representing the altitudinal limit of typical vegetation, the alpine timberline is a unique natural landscape that is also a sensitive indicator of the well-being of alpine ecosystems. Schrenk spruce (P. schrenkiana) is a tree species unique to arid Central Asia. In this study, we found that the P. schrenkiana can grow at elevations of up to 3600 m. To better understand how this species survives at such high elevations, we used tree-ring samples to analyze the relationship between climate and the radial growth of P. schrenkiana at the alpine timberline. Our results suggest that the mean minimum temperature during the growing season is the main factor limiting the radial growth of timberline P. schrenkiana. The limiting effect of temperature on radial growth has been significant and stable over the past 60 years. However, the influence of precipitation on tree growth has increased due to rapid warming. Continued warming may further complicate the response of P. schrenkiana radial growth to climate at the timberline in arid Central Asia.