Experimental evidence that effects of megaherbivores on mesoherbivore space use are influenced by species’ traits
Wells, Harry (2021), Experimental evidence that effects of megaherbivores on mesoherbivore space use are influenced by species’ traits, Dryad, Dataset, https://doi.org/10.5061/dryad.9ghx3ffhp
The extinction of 80% of megaherbivore (>1,000 kg) species towards the end of the Pleistocene altered vegetation structure, fire dynamics, and nutrient cycling worldwide. Ecologists have proposed (re)introducing megaherbivores or their ecological analogues to restore lost ecosystem functions and reinforce extant but declining megaherbivore populations. However, the effects of megaherbivores on smaller herbivores are poorly understood.
We used long-term exclusion experiments and multispecies hierarchical models fitted to dung counts to test 1) the effect of megaherbivore (elephant and giraffe) presence-absence on the occurrence (dung presence) and use intensity (dung-pile density) of mesoherbivores (2–1,000 kg), and 2) the extent to which the responses of each mesoherbivore species was predictable based on their traits (diet and shoulder height) and phylogenetic relatedness.
Megaherbivores increased the predicted occurrence and use intensity of zebras but reduced the occurrence and use intensity of several other mesoherbivore species. The negative effect of megaherbivores on mesoherbivore occurrence was stronger for shorter species, regardless of diet or relatedness.
Megaherbivores substantially reduced the expected total use intensity (i.e., cumulative dung density of all species) of mesoherbivores, but only minimally reduced the expected species richness (i.e., cumulative predicted occurrence probabilities of all species) of mesoherbivores (by <1 species).
Simulated extirpation of megaherbivores altered use intensity by mesoherbivores, which should be considered during (re)introductions of megaherbivores or their ecological proxies. Species’ traits (in this case shoulder height) may be more reliable predictors of mesoherbivores’ responses to megaherbivores than phylogenetic relatedness, and may be useful for predicting responses of data-limited species.
This dataset consists of dung surveys (belt transects) in two long-term herbivore exclosure experiments in a Kenyan savanna ecosystem.
See the Materials and Methods section of the publication for more details.
Area surveyed ('AREA') is in m2.
For megaherbivore accessibility ('MEGA'), 'YES' = accessible, 'NO' = excluded.