Soil nutrients and microbial community resistant to patch-burn grazing in southwestern North Dakota

Authors: Spiess, Jonathan; GASCH, CALEY - University Of Alaska; McGranahan, Devan; HOVICK, TORRE - North Dakota State University; BERTI, MARISOL - North Dakota State University; GEAUMONT, BENJAMIN - North Dakota State University

Submitted to: Ecological Monographs
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2026
Publication Date: 8/12/2026
Citation: Spiess, J.W., Gasch, C.K., Mcgranahan, D.A., Hovick, T.J., Berti, M., Geaumont, B.A. 2026. Soil nutrients and microbial community resistant to patch-burn grazing in southwestern North Dakota. Ecological Monographs. 17(8). Article e70727. https://doi.org/10.1002/ecs2.70727.
DOI: https://doi.org/10.1002/ecs2.70727

Interpretive Summary: Soil nutrient pools and microbial communities are important indicators for evaluating soil health in rangelands, but there is little relevant information about how the combination of prescribed fire and livestock grazing influences these indicators. This combination of disturbances is used to balance livestock production and habitat management goals in rangelands. We investigated how this management framework focused on aboveground responses potentially affects below-ground nutrient pools and microbial communities and found that differences soil nutrient pools and microbial responses were driven more by soil type than management. The lack of significant, negative effects on soil nutrients and microbes is a positive outcome in this instance, because it is illustrating how managing for aboveground responses using prescribed fire and livestock grazing does not have to come at the expense of below-ground resources.

Technical Abstract: Patch-burn grazing uses the interactive effects of prescribed fire and herbivory to increase heterogeneity in aboveground ecosystem properties. Understanding how management that targets aboveground heterogeneity translates to soil properties and processes provides an important whole-system context for practitioners. In this study, we investigated how the combination of patch-burning and livestock grazing aligned with soil nutrients, decomposition activity, and microbial abundance and composition on semi-arid post-Conservation Reserve Program rangelands in Southwestern North Dakota. We collected soil samples during the 2018 – 2020 summer grazing seasons in three patch-burn pastures grazed by cow-calf pairs and three patch-burn pastures grazed by sheep. In each year, we measured ammonium, nitrate, calcium, magnesium, phosphorus, potassium, total carbon, and total nitrogen. In 2019 and 2020, we measured soil moisture, decomposition activity, and microbial abundance and community composition. We tested for differences between patches with varying time since fire, between grazer type, and between ecological sites using mixed-effect models with Tukey post-hoc tests and ordinations with post-hoc factor and vector fitting. There were no significant differences in any properties between cattle and sheep pastures. Measured nutrients and microbial abundances were not lower in recently burned patches than not yet burned or patches with three years since fire. Bacterial groups comprised the largest proportion of the microbial community across years, ecological sites, and times since fire. Soil moisture, calcium, phosphorus, potassium, total carbon, total carbon:nitrogen ratio, time since fire, and ecological site were significantly correlated with microbial community composition. That we did not find negative responses in soil biota and properties to patch-burn grazing is promising for the continued use of these disturbances in low diversity rangelands.