Complexity of the soil microbial community
Complexity of the soil microbial community network (fungi-only network and bacteria-only network) showed distinct trends from those seen for the plant-microbiota networks, and were more strongly associated with soil factors than plant community parameters (Fig 5).
Random Forest analysis showed that the fungi-only network complexity was principally controlled by soil total phosphorus (STP) (Fig 5a&S8) while bacteria-only network complexity was dominated by soil moisture (SM) (Fig 5b&S9). In the fungal network, significant and positive linear correlations were found between STP and the number of nodes, number of edges, average degree, edge density, clustering coefficient, and degree centralization (Fig. 5c&S10). Significant and negative linear correlations were found between STP and average path length, modularity, betweenness centralization and eigenvector centralization (Fig. S10). The opposite trend was observed in bacterial networks, significant and negative linear correlations were found between SM and the number of nodes, number of edges, average degree, edge density, clustering coefficient, and degree centralization (Fig. 5d&S11). Significant and positive linear correlations were found between SM and average path length, modularity, betweenness centralization and eigenvector centralization (Fig. S11). These findings were supported by the results of the multiple regression on distance matrices analysis (Fig S12), indicating that increasing STP enhanced the network connections among fungi while increasing SM weakened the network connections among bacteria.
Discussion .