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Abstract Nitrogen (N) availability is a well‐known driver of ecosystem structure and function, but as air quality regulations continue to reduce atmospheric N deposition, there is a need to understand how managed and unmanaged ecosystems respond to widespread decreases in terrestrial N availability. Historical N eutrophication, from pollution or fertilisation, may continue to constrain contemporary responses to decreases in available N because of altered plant and microbial feedbacks. Thus, while certain management practices like prescribed fire remove N from grassland ecosystems, the role of fire supporting ecosystems recovering from chronic N input is unknown.To address this knowledge gap, we ceased a 30‐year N‐fertilisation treatment at a field experiment in a tallgrass prairie ecosystem crossed with burned and fire‐suppressed (unburned) treatments. We established subplots within each previously fertilised, recovering plot, fertilised at the same historical rate (10 g N m⁻² year⁻¹as NH₄NO₃), to compare plant and soil properties in recovering plots with control (never‐fertilised) and still‐fertilised treatments within different fire regimes.We document different N‐fertilisation legacies among ecosystem properties in burned and unburned prairies recovering from N‐fertilisation. Soil N availability, nitrification and denitrification potentials in recovering plots remained higher than controls for 3–5 years—indicative of positive legacies—in both burned and unburned prairies, but burning did not reduce this legacy. In burned prairies, however, a positive legacy in above‐ground plant production persisted because a more productive grass species (switchgrass) replaced the previously dominant species (big bluestem) even though root C:N, but not soil C:N, increased to return back to control levels. Consequently, the main N loss pathways in burned and unburned prairies (pyrovolatilisation and microbially mediated processes, respectively) led to similar losses of soil total N (20–28 g N m⁻²) over 5 years.Synthesis: Our results indicate that N eutrophication induces positive legacies of ecosystem functions that can persist for at least half a decade. N‐induced legacies arise because of shifts in soil microbial N‐cycling and plant functional traits. As a result, different management practices may elicit similar trajectories of ecosystem recovery in terms of total and available soil N because of different plant and microbial feedbacks. 

ABSTRACT Organisms inhabiting extreme environments must tolerate a variety of physiochemical stressors. In some cases, host‐associated microbial communities facilitate the survival of their hosts in extreme environments, but extremophile symbioses have not been identified in vertebrates. We used 16S rRNA amplicon sequencing to investigate commonalities and differences in the gut bacterial communities of livebearing fishes (Poecilia mexicanaspecies complex, Poeciliidae) that have repeatedly colonised toxic sulfide streams in southern Mexico. We found shared gut microbial taxa across habitat types and drainages but also differences in the microbiomes between sulfidic and nonsulfidic populations, both in terms of patterns of diversity and community composition. Most importantly, we documented convergent changes in microbiome composition across evolutionarily independent sulfide spring lineages. These patterns were consistent when we analysed the gut microbiomes as well as primarily host‐associated microbiomes that excluded taxa that are commonly found in the environment. Our analyses also revealed several microbial taxa associated with sulfide spring coloniation that have previously been implicated in symbioses and may influence the host's tolerance to the extreme environmental conditions. Our study sheds light on how shared environmental pressures can give rise to convergent host‐microbiome associations in fishes, and it provides a foundation for investigating the role of host‐microbiome interactions in vertebrate adaptation to extreme environments. 

Abstract Nitrogen (N) is a necessary element of soil fertility and a limiting nutrient in tallgrass prairie but grazers like bison and cattle can also recycle N. Bison and cattle impact the nitrogen (N) cycle by digesting forage that is consumed, and recycled back to the soil in a more available forms stimulating soil microbial N cycling activities. Yet we do not know how both grazers comparatively affect N cycling in tallgrass prairie. Thus, we investigated if bison and cattle had similar impacts on N cycling in annually burned tallgrass prairie relative to ungrazed conditions over a 3-year period (2020–2022) at the Konza Prairie Biological Station. We examined: soil pH, soil water content, mineralized N, nitrification potential, denitrification potential and extracellular enzyme assays. Interannual variability in precipitation controlled soil water and N cycling microbial activities but grazing effects had a stronger influence on N cycling. We found significant differences and increased soil pH, nitrification and denitrification potential and less N limitation in bison vs cattle grazed soils where bison grazed soils exhibited faster N cycling. Differences between the grazers may be attributed to the different management of bison and cattle as both can impact N cycling. Overall, these data provide some evidence that bison and cattle affect N cycling differently at this study site, and improve the ecological understanding of grazer impacts on N cycling dynamics within the tallgrass prairie ecosystem. 

Microbial communities display biogeographical patterns that are driven by local environmental conditions and dispersal limitation, but the relative importance of underlying dispersal mechanisms and their consequences on community structure are not well described. High dispersal rates can cause soil microbial communities to become more homogenous across space and therefore it is important to identify factors that promote dispersal. This study experimentally manipulated microbial dispersal within different land management treatments at a native tallgrass prairie site, by changing the relative openness of soil to dispersal and by simulating vector dispersal via bison dung addition. We deployed experimental soil bags with mesh open or closed to dispersal, and placed bison dung over a subset of these bags, to areas with three different land managements: active bison grazing and annual fire, annual fire but no bison grazing, and no bison grazing with infrequent fire. We expected microbial dispersal to be highest in grazed and burned environments, and that the addition of dung would consistently increase overall microbial richness and lead to homogenization of communities over time. Results show that dispersal rates, as the accumulation of taxa over the course of the 3-month experiment, increase taxonomic richness similarly in all land management treatments. Additionally, bison dung seems to be serving as a dispersal and homogenization vector, based on the consistently higher taxon richness and increased community similarity across contrasting grazing and fire treatments when dung is added. This finding also points to microbial dispersal as an important function that herbivores perform in grassland ecosystems, and in turn, as a function that was lost at a continental scale following bison extermination across the Great Plains of North America in the nineteenth century. This study is the first to detect that dispersal and vector dispersal by grazing mammals promote grassland soil microbial diversity and affect microbial community composition. 

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.