Resistance of the soil microbial community to land-surface disturbances of high-intensity winter grazing and wildfire

Common land-surface disturbances in rangelands with potential to influence the resistance and resilience of the ecosystem include livestock grazing and fire. The impact of these land-use disturbances on the soil microbial community is important to understand because the soil microbial community provides and supports many ecosystem services. Conventional management of land-surface disturbances have led to a decrease in the ecosystem services provided by rangelands. To combat this decrease, alternative land-surface disturbance regimes are being investigated. Therefore, this study assessed the impact of alternative land-surface disturbances (high-intensity winter-grazing and a wildfire, compared to a widely used conventional summer-long continuous grazing on the soil microbial community measured by changes in total soil microbial biomass, soil microbial functional groups, and soil microbial diversity. The soil microbial community was evaluated at beginning of the growing season and peak growing season for two years following the treatments. Prior to the treatments, the pastures had a long history of summer-long continuous grazing. Our results indicate that the soil microbial community is resistant to land-surface disturbance treatments (high-intensity winter-grazing and wildfire) although the response of soil microbial community was influenced by the composition of aboveground vegetation. Overall, neither wildfire nor high-intensity winter-grazing caused significant impacts on the soil microbial community.