Effects on diversity measures
Overall, measures related to species diversity, i.e. richness, evenness
and cover were all influenced by grassland type and showed no evidence
of interactions. There was strong evidence of season having an effect on
species richness. There was only weak evidence of prairie dog
disturbance having an effect on cover, but on the other hand there was
moderate evidence of prairie dog disturbance having interactive effects
on functional diversity measures, specifically on FSpe and RaoQ (Table
2).
There was strong evidence of mountain grasslands having a positive
effect on richness and cover, and these were higher than in all other
grassland types (Fig. 2a & b). The wet season positively affected
richness compared to the dry season (Fig 2d). There was weak evidence of
prairie dog disturbance having a negative effect on cover (Fig. 2e). On
the other hand, contrary to richness, there was strong evidence of
evenness being higher in both agricultural and arid grasslands, compared
to mountain grasslands which showed a negative effect (Fig. 2c).
There was no evidence that FEve was influenced by any of the variables
nor their treatments or interactions, similar to FDiv which showed no
evidence after pairwise post-hoc analysis (Appendix S3, Table S2). The
FSpe model revealed strong evidence of grassland type moderating the
effect of prairie dog disturbance on FSpe. This effect was particularly
important for agricultural grasslands where sites with prairie dogs had
a lower FSpe than sites without prairie dog disturbance (Fig 2f). RaoQ
showed strong evidence of being influenced by the interaction of prairie
dog disturbance and season. Grasslands without prairie dog disturbance
(WOP) had higher RaoQ during the dry season compared to the wet season.
There was no evidence of differences in RaoQ between seasons for
grasslands disturbed by prairie dogs (WP). In the wet season, no
evidence was shown regarding differences between conditions of prairie
dog disturbance, in contrast to the dry season where RaoQ values varied
greatly between conditions (Fig 2g).