Effect of altitude on climate–growth relationships of Chinese white pine (Pinus armandii) in the northern Funiu Mountain, central China

We developed three tree-ring width chronologies of Chinese white pine (Pinus armandii) along an altitudinal gradient on the same slope of the northern Funiu Mountain, central China. Chronological statistics indicate that there are higher mean sensitivity (M.S.) and standard deviation (S.D.) at high-altitude site while higher signal-to-noise ratio (SNR) and expressed population signal (EPS) at low-altitude site. Correlation analyses between chronologies and climate factors indicate that temperature is the main limiting factor, and discrepant response on tree growth exists at different altitudes. Mean and maximum temperatures in May have significant negative correlations with tree growth at mid and high altitudes, while all temperatures in April show significant positive correlations at high altitude and minimum temperature in August shows significant positive correlation at low-altitude site. It is evident that the limit of temperatures in April and May to tree growth strengthened with increasing altitude. Tree growth also shows significant positive correlations with precipitation in May at high altitude, with precipitation from prior December to current February and scPDSI (self-calibrating Palmer Drought Severity Index) from prior July to current February and May at mid altitude and relative humidity in February and June and scPDSI in current June at low-altitude site. Stability of climate–growth responses by moving correlation analyses shows continuous significant negative correlations with mean and maximum temperature in May and significant positive correlation with precipitation in May at high and low altitudes since 2000 but discontinuously significant negative correlation with precipitation in July–September before 2003 and discontinuously significant positive correlation with precipitation from prior December to current February after 1995. The strong significant positive correlations with scPDSI from prior November to current June since 1990 may indicate that temperature had induced drought stress on tree radial growth at mid-altitude site.