Grass species richness
Grass species richness did not differ significantly among habitats and bedrocks. Although the overall tests on the differences between habitats in models with herbivore abundance and species richness were significant and marginally significant, respectively (Table 2), no significant differences were detected between pairs of individual habitats (Fig. 6A and B). The highest grass species richness was recorded on granitic crests; however, the interaction of bedrock and habitat was not significant.
Herbivore abundance and species richness significantly interacted with bedrock (p = 0.034) but were not significant as main effects (Table 2). Grass species richness increased with herbivore abundance on basalts and decreased on granites (Fig. 7).
Grass species richness was significantly positively related to herbivore species richness at crests (p = 0.017) and negatively at seasonal rivers (p = 0.018); the relationship was non-significant at perennial rivers (p = 0.516, Fig. 8A). For the two bedrock types, the relationship between grass- and herbivore species richness was similar to that between grass species richness and herbivore abundance, i.e., significantly positive on basalt (p = 0.040) and negative on granite (p = 0.018, Fig. 8B).