3.4 Effects of key soil properties on fungal community composition
Soil properties explained 37.4% of the total variance of the fungal community composition at the OTU level (RDA analysis). The community structure of Forest was more closely associated with soil SWC, SOC, DOC, C/N, TN, and NH4+, and activities of SC, ACPT, ACP, and ALP (Fig. 7a). By contrast, those of the Berry and Peach were more strongly affected by pH, TP, AP, NO3-, Ca, Mg, TK, AK, BD, GLS and UR activities (p < 0.05). Pearson’s correlation indicated that the dominant phyla had strong correlation with soil quality indicators (Fig. 7b; Table S5). For instance, the relative abundance of Basidiomycota decreased with the reduction of SOC content (p=0.033) and GLS (p =0.042).
The SEM model indicated that the key predictors collectively accounted for 42% of the variation in fungal community diversity (Fig. 8). This model depended on the contents of pH, TP, TN and SOC affected by conversion. In particular, fungal diversity was directly and positively mediated by the key soil quality indicators including TP (path coefficient = 0.54, p <0.01) and pH (path coefficient = 0.51, p <0.001), and probably indirectly affected by the contents of SOC, DOC and TN (Fig. 8). The fungal diversity also had a direct negative impact on DOC contents (path coefficient = -0.19,p <0.001), SC (path coefficient =-0.38, p<0.01) and ALP activities (Fig. 8). The key soil quality indicator SOC was positively and directly related to TN, DOC and SC activities (Table S7), and it also increased with ALP activities via SC. However, SOC exerted a direct positive impact on TP (Fig. 8).