Fig. 4: Results of the structural equation model (SEM) on log-transformed response ratio (LRR) of herbaceous community foliar fungal pathogen load between shrub patches and grassland patches’ plots (i.e., LRR pathogen load) and partial regression plots.

a SEM illustrates the results of mean annual temperature (MAT), mean annual precipitation (MAP), LRR of herbaceous plant community aboveground biomass (i.e., LRR herbaceous biomass), community weighted mean of height (i.e., LRR CWM of height), and species richness (i.e., LRR species richness) influencing LRR pathogen load. Solid blue arrows denote positive pathways, solid brown arrows indicate evidence for negative pathways, and dotted arrows illustrate insufficient statistical evidence for path coefficients. The strength of the causal relationship is denoted by the width of the arrows. b Partial regression plots illustrate the effects of MAT, MAP, LRR herbaceous biomass, LRR CWM of height, and LRR species richness residuals influencing LRR pathogen load residuals from the SEM. Parameter significance was assessed by F-tests (two-tailed). Dotted lines, solid lines, and shadows represent marginal significant effects (0.05 < P < 0.10), significant effects (P < 0.05), and 95% confidence intervals, respectively; n = 320 for the SEM and these partial regression plots.