Herbivore size matters for productivity-richness relationships in African savannas

1.Productivity and herbivory often interact to shape plant community composition and species richness with levels of production mediating the impact of herbivory. Yet, differences in herbivore traits such as size, feeding guild, and dietary requirements may result in different impacts of diverse herbivore guilds across productivity gradients.

2.We used size-selective herbivore exclosures to separate the effects of herbivory by larger herbivores, such as elephant, Burchell's zebra, and blue wildebeest from those of medium/smaller herbivores, such as impala and warthog, on herbaceous plant communities. These exclosures were established along a 10-fold productivity gradient, ranging from 90-950 g m−2 of standing plant biomass in the Kruger National Park, South Africa.

3.Exclusion of all herbivores generally increased plant species richness at low productivity but decreased richness at high productivity. Exclusion of medium/smaller herbivores (e.g. impala, warthog) showed stronger eff...