Ecosystem engineering effects on grassland ecosystem function vary with animal type and function

1. Soil-disturbing mammals are important ecosystem engineers in grasslands where they influence a range of ecosystem attributes and processes. Yet the extent to which these effects vary with different species and body size has been little studied. We examined the impacts of four groups of soil-disturbing engineers on ecosystem functions, testing two key hypotheses: (i) the relative impact of engineering on various ecosystem response variables differs with specific function or attribute, but there is a consistent overall effect across these attributes among different taxa. (ii) the relative effects of engineering on structural, functional, and compositional metrics are moderated by the body size of the engineers.2. We examined the impacts of four groups of semi-fossorial mammals (Lepus capensis, Marmota sibirica, Microtus brandti, Meriones unguiculatus/Myospalax psilurus) of varying body size on a range of plant and soil functions in the eastern Eurasian steppe.3. We found that engineering by these mammals significantly affected 88% of the studied attributes, and any effects varied with the identity of the engineer and the ecological outcome. Engineered patches has greater plant function and lower structure, but there were no effects on composition. Although the identity of the engineer generally had no effect, body size was important, with more negative impacts for larger body-sized engineers.4. Synthesis. Our findings demonstrate that animal disturbances exert substantial yet heterogeneous impacts on grassland ecosystems. While plant biomass, cover, and soil nutrient functions are adversely affected, shifts in diversity and plant nutrient composition highlight the complex, multifactorial nature of disturbance effects. These results underscore the need for integrated management strategies that simultaneously address the abiotic and biotic consequences of animal activities to maintain grassland health and resilience.