Relationship between the Radial Growth of Two Dominant Coniferous Species and GPP in the Arid Region of Northwest China

Radial growth of trees is closely related to canopy activity. Revealing the relationship between radial growth and canopy activity is of great significance for forest protection under climate change. In this study, we built tree-ring chronologies for two tree species, spruce (Picea aspruceerata) and Chinese pine (Pinus tabuliformis), from the Helan Mountains in the arid region of northwest China. Correlation coefficients were then calculated to reveal the relationships among tree rings, two kinds of gross primary productivity (GPP) indices, and climate data. The results demonstrated that the radial growth of both spruce and Chinese pine was positively correlated with GPP from late February to early March, and moisture conditions may be the driving factor of tree growth. However, radial growth of Chinese pine was also correlated with GPP from the end of March to the end of August. This study aimed to further supplement the relationship between trunk radial growth and canopy dynamics in the arid zone of northwest China and to provide theoretical guidance for vegetation restoration and forest conservation in the arid zone of northwest China under climate change.