Climate response and radial growth of Pinus tabulaeformis at different altitudes in Qilian Mountains

In order to test whether the relationship between climate and the radial growth of trees is affected by altitude, altitude variability and time stability of climate-influenced radial growth of a dominant conifer, Chinese pine (Pinus tabulaeformis), in the eastern Qilian Mountains were studied against the background of climate change using dendrochronology. Results show that 1) droughts at the end of the growing season of last year and during the early and middle growing season of the current year were the main limiting factors for the radial growth of Chinese pine at two altitude gradients; this was determined by analyzing the relationship between tree-ring width chronologies and climate factors. 2) The sensitivity of the radial growth of trees to climate change gradually decreased and was affected more by drought stress at a lower altitude. 3) An unstable divergence response was observed in the radial growth at the two altitudes, in response to controlling climatic factors; this observation was based on the moving correlation analysis of growth/climate relationships, and the aggravation of drought stress caused by increasing temperature was the main reason. 4) The growth rate of Chinese pine at the two altitudes increased at first and then decreased, as measured by basal area increment (BAI) modeling. Future temperature rises may have significant effects on mountain forest ecosystems in arid and semi-arid regions. Effective management and protection measures should be taken, according to the response patterns of trees to climate change at different altitude gradients.