Biocrusts indicators of livestock grazing effects on soil stability in sagebrush steppe: A case study from a long-term experiment in the northern Great Basin

Authors: Copeland, Stella; CONDON, LEA - Us Geological Survey (USGS); ROSENTRETER, ROGER - Boise State University; MILLER, JESSE - Stanford University; KAHN-ABRAMS, MAYA - Former ARS Employee

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2023
Publication Date: 9/29/2023
Citation: Copeland, S.M., Condon, L., Rosentreter, R., Miller, J., Kahn-Abrams, M. 2023. Biocrusts indicators of livestock grazing effects on soil stability in sagebrush steppe: A case study from a long-term experiment in the northern Great Basin. Rangeland Ecology and Management. 91:82-86. https://doi.org/10.1016/j.rama.2023.09.001.
DOI: https://doi.org/10.1016/j.rama.2023.09.001

Interpretive Summary: Biocrusts, communities of lichens, mosses, and soil microorganisms growing on the soil surface, are prominent in many drylands, including sagebrush steppe. They may be useful indicators of ecosystem functions, particularly soil properties like stability, which may suggest the potential for soil erosion. We evaluated differences in biocrusts and associated soil stability with or without long-term cattle grazing exclusion in several paired sites in a sagebrush steppe rangeland in the northeastern Great Basin. Cover of several biocrust groups, especially lichens, and soil stability was higher in the exclosure areas compared to the grazing sites, but there was also high variability in differences across plot pairs despite similar vegetation, perhaps due to finer scale differences in livestock grazing intensity and sand content. Though lichens were sensitive to changes in soil stability with grazing, similar to findings in other western rangelands, they were also in low abundance (1% cover on average), and moss, which was more abundant, might be a better biocrust indicator of soil stability change in this site. Overall our results suggest that biocrust communities may useful indicators of rangeland ecosystem functions, like soil properties, but specific indicator groups should be identified based on site characteristics.

Technical Abstract: Biocrusts are sensitive to changes in livestock grazing intensity in arid rangelands and may be useful indicators of ecosystem functions, particularly soil properties like soil stability, which may suggest the potential for soil erosion. We compared biocrust community composition and surface soil stability in a big sagebrush (Artemisia tridentata) steppe rangeland in the northwestern Great Basin in several paired sites, with or without long-term cattle grazing exclusion, and similar soils (mostly sandy loams), climate, and vegetation composition. We found that livestock grazing was associated with both lower surface soil stability and cover of several biocrust morphogroups, especially lichens, compared with sites with long-term livestock exclusion. Surface soil stability did not modify the effects of grazing on most biocrust components via interactive effects. Livestock grazing effects on total biocrust cover were partially mediated by changes in surface soil stability. Though lichens were more sensitive to grazing disturbance, our results suggest that moss (mostly Tortula ruralis in this site) might be a more readily observable indicator of grazing-related soil stability change in this area due to their relatively higher abundance compared with lichens (moss: mean, 8.5% cover, maximum, 96.1%, lichens: mean, 1.0% cover, maximum, 14.1%). These results highlight the potential for biocrust components as sensitive indicators of change in soil-related ecosystem functions in sagebrush steppe rangelands. However, further research is needed to identify relevant indicator groups across the wide range of biocrust community composition associated with site environmental characteristics, variable grazing systems, other rangeland health metrics, and other disturbance types such as wildfire.