To understand why the sensitivity of τ _e,C andτ _e,P to T _min had a breaking point around T _min = 0 ℃, we divided the data from 127 forest sites into two groups using theT _min values for those sites, and estimated the correlations between τ _e,C andτ _e,P with 30 variables (see Fig. 5).

Correlations between the τ _e,C,τ _e,N and τ _e,P withT _min or MAT were negative whenT _min < 0 ℃, and became insignificant or positive when T _min > 0 ℃, which is consistent with the results in Fig. 4. Furthermore, those correlations with several climate-related variables were all negative whenT _min < 0 ℃, suggesting as temperature or precipitation increased, ecosystem residence times became shorter. When T _min > 0 ℃, correlations with most climate-related variables became positive or insignificant (see Fig. 5), suggesting the direct effect of temperature or precipitation changes on τ _e,C, τ _e,N andτ _e,P was weakened, as temperature increase is found to shorten ecosystem residence time.

Correlations of τ _e,C, τ _e,Nor τ _e,P with vegetation-related variables also changed sign between above and below T _min of 0 ℃. For example, τ_e,P was negatively correlated with leaf area index (LAI) at T _min < 0 ℃, but becmae positively correlated with LAI when T _min> 0 ℃. Correlation of τ _e,C with the leaf resorption of N or P was not significant atT _min < 0 ℃, but became significantly negative at T _min > 0 ℃.

Correlations of τ _e,C, τ _e,Nand τ _e,P with soil- or terrain-related variables were generally low. When T _min < 0 ℃,τ _e,P was negatively correlated with soil clay content, slope gradient, but positively correlated with bulk density and pH. When T _min > 0 ℃,τ _e,C significantly increased with elevation.

In summary, τ _e,C and τ _e,Pdecreased with an increase in T _min whenT _min < 0 ℃, which is consistent with most previous studies, but increased with T _minwhen T _min > 0 ℃, which differes from most previous studies on the effect of temperature change on ecosystem residence time.