Bulk Soil 16S ITS, and 18S amplicon from Patch-Burn Grazing Managed Grasslands

Grasslands are dynamic ecosystems threatened by invasive plants, where fire and grazing management are used to maintain biodiversity and ecosystem function. Patch-burn grazing, which integrates prescribed fire with livestock grazing, mimics historical practices and has been proposed as a strategy to restore grassland heterogeneity. However, the effects of these disturbances on soil microbial communities, especially in invaded grasslands, remain underexplored. In this study, we used amplicon sequencing of bacterial, fungal, and protist communities to examine how patch-burn grazing influences microbial structure, diversity, and function over a 4-year fire return interval. Fungal and protist communities showed significant shifts, while bacterial communities remained unchanged. Soil nutrient availability, mainly carbon, nitrogen, and phosphorus, correlated with microbial composition, suggesting that fire-driven nutrient changes affect microbial assembly. Additionally, plant community shifts were linked to microbial responses, with native and invasive species associating with distinct microbial taxa. Indicator species analysis revealed Geobacterales, Cantharellales, and Corticiales associated with different recovery stages. We also observed an increase in fungal saprotrophs and a decrease in mycorrhizal fungi. Our analysis of stochasticity and determinism revealed that patch-burn grazing primarily determined fungal communities. Native forbs and graminoids increased initially but later declined, while non-native graminoids recovered fully by the final recovery year. These findings highlight how fire and grazing interactions shape microbial succession, with implications for understanding the sustainability of fire-based management practices. Our study provides valuable insights into microbial dynamics in invaded grasslands and informs strategies for ecosystem restoration.