Ecological heterogeneity: Evaluating small mammal communities, soil surface temperature and artificial nest success within grassland ecosystems

Scope and method of study. This study focused on the role of ecological heterogeneity for conservation and preservation of biodiversity within grassland ecosystems. The heterogeneity model implemented a fire regime that acts to shift grazing disturbances to more recently burned areas, where patches associated with a fire-return interval ≥3 years are dominated again by tallgrasses and high litter accumulation.; Findings and conclusions. Application of our grazing-fire model contributed to ecological heterogeneity and enhanced biodiversity of vegetation cover and small-mammals. Patch-level heterogeneity associated with patch burn treatments was 2.5- to 10-fold greater within patch burn treatments than on traditional treatments. The grazing-fire model supports the notion that heterogenous systems are capable of enhancing biodiversity. For instance, species diversity (within the patch burn treatment) increased with time since focal disturbance (grazing-fire interaction) and was greatest in patches that were associated with a fire-return interval between 25 and 36 months. Physiological condition parameters of deer mice, harvest mice, and prairie voles suggested that these species exhibited differential competitive abilities between traditional and patch burn patches. Effects of grazing on landscape heterogeneity are highly variable and depend primarily on the variable of interest and scale of observation. Soil surface temperatures were highly variable within a relatively small area. Grazing did not influence mean soil surface temperatures and results suggest that landscape position was the most important component moderating mean soil surface temperatures. Riparian areas that were associated with lower soil surface temperature may provide a critical thermal refuge for many animals on hot summer days when air temperatures can exceed 37°C. Grazing has a minimal influence on rates of artificial nest predation. Fire is perhaps the most important ecosystem component maintaining native grasslands, thus the grazing-fire model can be a useful conservation tool for many grassland ecosystems and can increase heterogeneity and maximize biodiversity by producing a shifting mosaic of habitat types through space and time.