Figure 4.

Non-metric multidimensional scaling (NMDS) ordination showing the distribution of abundant and rare subcommunities along the (A) latitude gradient and (B) mean annual precipitation gradient. The contour lines show the gradients. (C) Structural equation modeling analysis illustrating the relationships between location (including latitude, longitude, and elevation), climate (including mean annual temperature and mean annual precipitation), pH, conductivity, nutrient (including sediment organic carbon, total nitrogen, and total phosphorus), nutrient ratios (including C:N, C:P, and N:P ratios), and abundant and rare subcommunities. Solid and dashed arrows represent the significant and non-significant relationships, respectively. Red and green arrows represent positive and negative relationships, respectively. The significant path coefficient is shown adjacent to the path with *, **, and *** denote the significant level of p < 0.05, p < 0.01, and p < 0.001, respectively.