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Frequent fire and grazing by megafauna are important determinants of tallgrass prairie plant community structure. However, fire suppression and removal of native grazers have altered these natural disturbance regimes and changed grassland plant communities with potential long‐term consequences for soil carbon (C) and nitrogen (N) storage. We investigated multidecade changes in soil C and N pools in response to contrasting long‐term burning and grazing treatments. Fire suppression with or without grazers and exclusion of grazers in annually burned prairie increased soil C content and shifted the δ¹³C signature of soil C over time, concomitant with changes in plant community composition. Soil δ¹³C values indicated that increased soil C content was associated with an increased contribution from plants using a C₃photosynthetic pathway (i.e., woody shrubs) under fire suppression. Soil N content also increased when fire was suppressed, relative to frequently burned grassland, but the rate of increase was slower when grazers were present. Additionally, changes in δ¹⁵N values suggested that grazing increased the openness of the N cycle, presumably due to greater N losses. By coupling long‐term fire and grazing treatments with plant community data and soil samples archived over three decades, we demonstrate that human‐caused changes to natural disturbance regimes in a tallgrass prairie significantly alter soil C and N cycles through belowground changes associated with shifts in the plant community. Since natural disturbance regimes have been altered in grasslands across the world, our results are relevant for understanding the long‐term biogeochemical consequences of these ongoing land use changes.

 

Abstract Plant, soil, and aquatic microbiomes interact, but scientists often study them independently. Integrating knowledge across these traditionally separate subdisciplines will generate better understanding of microbial ecological properties. Interactions among plant, soil, and aquatic microbiomes, as well as anthropogenic factors, influence important ecosystem processes, including greenhouse gas fluxes, crop production, nonnative species control, and nutrient flux from terrestrial to aquatic habitats. Terrestrial microbiomes influence nutrient retention and particle movement, thereby influencing the composition and functioning of aquatic microbiomes, which, themselves, govern water quality, and the potential for harmful algal blooms. Understanding how microbiomes drive links among terrestrial (plant and soil) and aquatic habitats will inform management decisions influencing ecosystem services. In the present article, we synthesize knowledge of microbiomes from traditionally disparate fields and how they mediate connections across physically separated systems. We identify knowledge gaps currently limiting our abilities to actualize microbiome management approaches for addressing environmental problems and optimize ecosystem services. 

Human induced climate and land‐use change are severely impacting global biodiversity, but how community composition and richness of multiple taxonomic groups change in response to local drivers and whether these responses are synchronous remains unclear. We used long‐term community‐level data from an experimentally manipulated grassland to assess the relative influence of climate and land use as drivers of community structure of four taxonomic groups: birds, mammals, grasshoppers, and plants. We also quantified the synchrony of responses among taxonomic groups across land‐use gradients and compared climatic drivers of community structure across groups. All four taxonomic groups responded strongly to land use (fire frequency and grazing), while responses to climate variability were more pronounced in grasshoppers and small mammals. Animal groups exhibited asynchronous responses across all land‐use treatments, but plant and animal groups, especially birds, exhibited synchronous responses in composition. Asynchrony was attributed to taxonomic groups responding to different components of climate variability, including both current climate conditions and lagged effects from the previous year. Data‐driven land management strategies are crucial for sustaining native biodiversity in grassland systems, but asynchronous responses of taxonomic groups to climate variability across land‐use gradients highlight a need to incorporate response heterogeneity into management planning.