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).