*MAT: mean annual temperature, MTCQ: mean temperature of the coldest
quarter, solar_rad: solar radiation, PET: potential evapotranspiration,
MAP: mean annual precipitation, AI: aridity index, WD: water deficit;
calculated as the difference between PET and the actual
evapotranspiration (AET) (Francis and Currie 2003). TS: temperature
seasonality, PS: precipitation seasonality. ELER-SD: standard deviation
of elevation, ELER: elevation range, CLY: clay fraction, CRF: coarse
fragments, SLT: silt fraction, SND: sand fraction. AW: available water,
AN: available nitrogen, AP: available phosphorus, C_stock: organic
carbon stock, C_content: organic carbon content, C/N_ratio:
carbon/nitrogen ratio, CEC: cation exchange capacity.
Table 2. The best combinations of variables for each conifer
species group in South-western China evaluated using stepwise regression
and their coefficients of determination (R2). The best
models for each group were selected from 1344 models based on the lowest
Akaike information criterion (AIC). Numbers in parentheses are
coefficients of respective variables. The variance inflation factors
(VIF) for all predictors were less than 5 indicating insignificant
multicollinearity.