*2.5. Statistical Analyses*

The data were tested for homogeneity of variances (Brown and Forsythe's variation of Levene's test) before statistical analysis. In order to assess the Chinese fir fine root function on soil P supply, the rhizosphere effect (%) of P availability was defined as the difference between rhizosphere and bulk soils. Multiple-way analysis of variance (ANOVA) was used to determine the effect of stand type, site location, soil sources (rhizosphere vs. bulk soil), or tissue ages, and the interactions between stand type and site location on nutrient variables. One-way ANOVA and least significant difference (LSD) was used to compare the differences of mean values among the three orders of roots, or three age classes of needles and twigs. Pearson's tests were used for comparing the significance of correlations among soil P fractions and tree nutrient concentrations. SPSS 16.0 software (SPSS, Inc., Chicago, IL, USA) [30] was used to perform all analyses. The standard 0.05 level was used throughout as a cutoff for statistical significance.
