It's the little things: rangeland soil health indicators and microbial community response to deferred grazing in the Intermountain West

Abstract

Rangelands of the Intermountain West express unpredictable climate and environmental factors, causing plants in this region to be particularly sensitive to grazing early in the growing season. Soil microbial communities are foundational to soil health, mediating key processes that regulate vegetation productivity, nutrient cycling, organic matter formation, and ecosystem resiliency. In the extensive rangeland systems of the Intermountain West that support livestock grazing, the roles of the soil microbial community remain poorly understood. Well-managed and sustainable grazing practices on rangelands that allow for rest periods, can reduce pressure during critical growing periods, optimizing vegetation productivity through their impact on microbial biomass, species diversity, enzyme activity, and other functional traits such as carbon and nitrogen sequestration. Despite the global importance of rangelands, knowledge gaps exist regarding the impacts of specific grazing management approaches on microbial communities and soil health indicators. This review synthesizes the literature to clarify the influence of rangeland grazing management on four microbially-mediated soil health indicators: microbial biomass carbon (MBC), extracellular enzyme activity (EEA), soil organic carbon (SOC) pools, and microbial community structure and function. By clarifying existing patterns, key research gaps are identified and are accompanied by specific management recommendations to incorporate microbial ecology into rangeland and soil health assessments.