Land managers utilize managed disturbance regimes (hereafter, “management disturbances”), such as fire and grazing, to mimic natural disturbances at a landscape scale with the goals of increasing species diversity and supporting ecosystem functions. Such actions are predicated on the assumption that there is a direct relationship between the identity and diversity of species in a community and their associated function. We carried out a large-scale experiment using management disturbances in a tallgrass prairie restoration to test whether a species trait-based or identity-based perspective provides clearer insight about disturbance effects on ecosystem function. We measured species- and trait (niche breadth, body mass, C:N) -composition effects in consumer (small mammal) communities resulting from variation in environmental context (driven by these management disturbances). We also measured the ecosystem functions (soil C:N, decomposition rates, biomass) to which these consumers contribute to determine whether shifts in species/trait composition translate to functional changes and how those changes feed back up to consumers.
Results/Conclusions
Bison had no impact on mammal species richness, community composition, or abundance. The two most common mammals, Peromyscus maniculatus and Microtus ochrogaster are 11% and 7% heavier in mass, respectively in bison sites relative to non-bison sites, perhaps due to the increase in nutrient inputs leading to more or more nutritious food resources. These differences in mass were also seen in the same sites before and after bison were reintroduced. Small mammals were more abundant in years following burns, a trend likely driven by Peromyscus maniculatus, which particularly prefer sites with bare ground. Small mammal diversity and community composition did not change with prescribed fire. Small mammal niche breadth and C:N data are forthcoming. Small mammal trait differences in bison versus non-bison sites did not result in predictable differences in plant biomass. However, in sites where Peromyscus maniculatus were more abundant following fire, we found higher forb and lower grass biomass, perhaps in part from seedling and seed predation. Small mammal diversity and grass biomass increased with restoration age but small mammal abundance and forb biomass decreased with restoration age. Future work will conduct a structural equation model to identify the most important linkages between the variables and disturbances studied.