Small mammal community maintains stability through compensatory dynamics after restoration of a ponderosa pine forest

Ecosystem stability has been of increasing interest in the past several decades as it helps predict the consequences of anthropogenic disturbances on ecosystems. Species may exhibit stability through compensation, with greatly fluctuating populations year to year but a consistent density response over time. Stability is increased when species with similar functional roles compensate for one another by responding differently to environmental change. In restoration projects, the objective is to restore stability by altering ecosystem composition, structure, and function to resemble natural (‘‘reference’’) conditions. We assessed the success of ecological restoration treatments by examining the structural and functional responses of the small mammal community before and after treatment, and compared to reference conditions. We used Royle density models to examine the responses of eight species of small mammals to restoration (thinning) treatments in ponderosa pine forests to determine if the community maintained total density, biomass, and function (represented by ectomycorrhizal fungi dispersion) after disturbance. Community composition differed in each of 6 years following treatment, but total density and biomass remained constant, suggesting the community is a stable prey base for predators. In addition, goldenmantled ground squirrels (Spermophilus lateralis) and gray-collared chipmunks (Tamias cinereicollis) appeared to play a similar role in dispersing ectomycorrhizal fungi across different forest structures. Both total species density and biomass were greater after thinning than in unthinned stands, and were similar to reference stands. These results suggest that although species composition changes from year to year after disturbance, restoration treatments can maintain ecosystem stability in terms of small mammal community-level properties.