The Influence of Cheatgrass (Bromus tectorum) on the Small Mammal Community at the U.S. Army Dugway Proving Grounds, Utah

Ecosystem biodiversity is beneficial to all species on a given landscape and vital to proper functioning of ecosystem services. Due to the relative ease of capture, small mammal community diversity is a key tool for quantifying overall ecosystem health. Studies examining small mammal communities are numerous; however there have been few studies that have examined the effects of changing vegetation structure on rodent community dynamics of native animal species in cold-desert ecosystems. The loss of vegetative diversity is an area of concern in desert and shrub-steppe communities as invasive species such as cheatgrass (Bromus tectorum) provoke large changes in vegetation composition and structure. The health of these systems is vital to the conservation and management of sensitive species including the greater sage-grouse (Centrocercus urophasianus). Small mammal communities are also vital prey for a host of mammalian and avian predators. The impact of cheatgrass expansion on small mammal communities remains largely unexplored. In this study we examined community level small mammal responses to changes in microhabitat features, including levels of invasive species dominance. In the summers of 2010-2013, we sampled small mammals using Sherman live traps and measured vegetation structure using the line-point intercept method. Using estimates of richness, diversity, biomass and number of captures (i.e., response variables), we developed generalized linear mixed models (GLMMs) to test the predictor variables percent invasive species (predominantly cheatgrass), plant species richness, percent openness, percent shrubs, and percent litter. Final results are pending but preliminary findings suggest a negative relationship between percent invasive species and small mammal species richness and diversity, and a non-linear relationship between percent invasive species and biomass and number of captures. This research will fill gaps in the current literature and guide management actions, such as cheatgrass reduction/native vegetation restoration for management agencies