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Abstract BackgroundDisturbance is a natural part of all ecosystems and often creates a balance of resistance-resilience among taxa. Grassland ecosystems, and in particular tallgrass prairie, are model systems for studying the outcomes of disturbance regime shifts because they are disturbance-dependent (i.e., maintained by fire, grazing, or climate). The effects of changing disturbance regimes, such as fire frequency in mesic grasslands, are often assessed based on one or a few taxa. However, to support diverse management goals, land managers must consider the effects of their choices on many taxa. In this study, we addressed this gap using a meta-analysis of 37 studies from tallgrass prairie to assess the effects of different fire frequencies on arthropods, birds, plants, small mammals, and soil properties (referred to here as ecological factors) and the interactive effects of fire frequency and grazing, another important disturbance. ResultsAs expected, the abundance and diversity of taxa were affected by different fire frequencies. However, the directionality of the change varied among taxonomic groups, indicating that there is no “one-size-fits-all” fire-management strategy in tallgrass prairie. Annual fires promoted small mammal abundance but decreased plant abundance and diversity. Meanwhile, intermediate fire frequencies promoted plant abundance but at the cost of plant diversity, arthropod abundance, and soil total carbon and nitrogen. Grazing promoted plant abundance while reducing arthropod and obligate grassland-bird abundance. ConclusionsOur study revealed research gaps, with critical data missing from small mammals, birds, soil properties, and eastern tallgrass prairie. However, quantifying the differential responses of ecological factors to fire frequency, as we did here, can inform tallgrass prairie management strategies, providing an example of the potential for land managers to manipulate disturbance frequencies to meet diverse management goals. We outline the important tradeoffs associated with management strategies using fire frequency and highlight the potential for fire to be used in unison with grazing to create a more heterogeneous landscape conducive to tallgrass prairie. Multi-taxonomic syntheses like this one are needed for land managers and ecologists to harness the power of prescribed fire in order to increase grassland sustainability and health worldwide. 

Abstract Streptomycesare key contributors to soil microbiome function, known for their biosynthetic diversity. While advances in -omics technologies have improved our understanding of microbiome composition and metabolic potential, the mechanisms underpinning interspecies interactions remain poorly resolved. Here, we investigate the molecular basis of interactions among four sympatricStreptomycessoil microbiome isolates, focusing on phenotypic, metabolomic and transcriptomic responses. Co-culture experiments revealed that one isolate, strain A, exhibited pronounced phenotypic changes when grown alongside each of the other three strains. Untargeted metabolomics and RNA-seq analyses showed that strain A undergoes distinct metabolic and transcriptional shifts depending on its partner, with the strongest response elicited by strain C. Despite all four strains possessing a conserved desferrioxamine biosynthetic gene cluster, only strain C constitutively produced desferrioxamine B (DFO-B), a hydroxamate siderophore, indicating a role for iron bioavailability in the interaction. Supplementation with DFO-B or iron mimicked the growth stimulation of strain A observed in co-culture with strain C, and CRISPR base editing ofdesDin strain C abolished both DFO production and the phenotypic induction of strain A. However, transcriptomic profiles of strain A varied significantly depending on the partner strain, with distinct sets of biosynthetic gene clusters and metabolic pathways activated in response to strains B and C, suggesting additional cues beyond DFO-B. In contrast, strain D did not elicit growth stimulation in its partners, and itself showed downregulation of amino acid and carbon metabolism when co-cultured with strain C. These findings indicate thatStreptomycesinteractions are not only mediated by siderophore piracy but also involve complex, strain-specific molecular responses. Our findings demonstrate thatStreptomycesinteractions are highly strain-specific and only partly mediated by siderophore piracy, with DFO-B acting as a potent interspecies cue. The divergent molecular responses to different partners suggest nuanced mechanisms of microbial sensing and competition. These insights advance our understanding of microbial crosstalk and highlight the ecological and evolutionary complexity of siderophore-mediated interactions. By integrating transcriptomics, metabolomics, and biochemical assays, we present a robust framework for dissecting microbial interactions, with implications for microbiome engineering and synthetic community design. 

ABSTRACT QuestionIn addition to altering ecosystem states, anthropogenic changes may also alter the drivers of community dynamics within these ecosystems. Previous research has shown nitrogen as a key driver of community dynamics in grassland ecosystems, including those present at our study site. We sought to test whether these nutrient responses will shift as changes to disturbance regimes facilitate woody encroachment. LocationSuccessional grassland at Cedar Creek Ecosystem Science Reserve (Minnesota, USA). MethodsAs part of an investigation into the drivers and consequences of Eastern White Pine (Pinus strobus) encroachment at this site, we surveyed pine abundance and herbaceous community composition in 32 treatment plots, following 18 years of experimental fire, nitrogen, and herbivore manipulation. ResultsAlthough pine abundance varied widely in unburned plots, it did not significantly respond to nitrogen addition or herbivory. As expected, pine encroachment was dramatically inhibited in burned plots. Species richness in the herbaceous community did not differ significantly between treatments. The Shannon diversity index responded interactively to fire and nitrogen, with nitrogen addition decreasing diversity in unburned plots but increasing diversity in burned plots. Nitrogen's effects on the overall composition of the herbaceous plant community were contingent upon fire. Within the burned treatment, nitrogen addition led to an increase in the cover of invasive C3 grasses. Within the unburned treatment, nitrogen had no consistent effect on herbaceous species composition. ConclusionsDespite research showing nitrogen as a key driver of community dynamics in the grasslands of our study site, we found that this effect is contingent on the presence of fire and absence of woody encroachment. With this variation in nitrogen effects, we see that a factor playing a major role in structuring a community can cease to play that role as disturbance regimes and ecosystem states are altered. 

ABSTRACT AimGlobal climate change is compressing species' realised niches and further threatening their distributions. Species traits, especially the trait spectra synthesised from traits, are one way in which species can match changes in their environment. Hence, integrating trait spectra and niches will help us understand how species adapt to their environment under global change. LocationGlobal. Time PeriodPresent. Major Taxa StudiedAngiosperms. MethodWe collected root traits from 158 angiosperm species and leaf traits from 512 angiosperm species from a global trait database to construct the leaf and root trait ‘slow‐fast’ spectrum based on resource acquisition strategy, as well as the collaboration spectrum related to root mycorrhizal colonisation. After rebuilding their phylogenetic relationships and defining species' environmental niches based on 213,979 occurrences of these species, we examined the relationship between these trait spectra and environmental niches along global climatic patterns. ResultPlants with ‘slow’ leaf traits were generally associated with narrow niche breadths and marginal niche positions, especially in high precipitation areas. The relationship between the ‘slow‐fast’ spectrum in root traits and ‘marginal‐central’ niche position reversed with decreasing precipitation. However, the relationships between leaf traits and niche variables were significant for woody species but not for herbaceous species. Main ConclusionOur research expands the plant trait spectra in macroecology applications. The root and leaf ‘slow‐fast’ trait spectra of angiosperms are driven by both macroclimate and long‐term evolutionary pressure. Understanding how these traits relate to the niche of species helps to predict how that species is likely to adapt to environmental change, which can enhance the predictive ability of niche theory for plant environmental adaptability. 

ABSTRACT AimThe consistency of patterns in ontogenetic differences in plant traits across the globe has not been thoroughly studied. Environmental conditions affect leaf functional traits, and these effects can differ between adult trees and saplings due to varying environmental conditions in their aerial and soil environments. Our integrative analysis aims to reveal the global universality of woody plants' ontogeny and explores influencing factors. LocationGlobal. Time PeriodStudies published in 1989–2023. Major Taxa StudiedWoody plants. MethodsWe performed a global meta‐analysis of woody plants with different plant functional types at 64 sites around the world, assessed the ontogenetic differences in nine key leaf traits and explored the environmental factors that affected the ontogenetic differences. ResultsWe observed that (1) leaf traits differed significantly between adult trees and saplings, with environmental factors playing varying roles. Photosynthetic capacity per unit area (A_a) and nitrogen content per unit dry mass (N_m) were lower in saplings than in adults under low solar radiation, but this trend reversed with increased solar radiation. Differences in stomatal density (SD) and stable carbon isotope composition (δ¹³C) between adults and saplings were greatest under low solar radiation; (2) ontogenetic differences in leaf thickness (LT), leaf dry mass per area (LMA) and stomatal conductance (g_s) were greater at lower mean annual temperature (MAT); (3) at high mean annual precipitation (MAP), adults had higher nitrogen content per unit area (N_a), while saplings had higherN_mthan adults; (4) soil conditions were strongly correlated with ontogenetic differences in LT and SD, with soil pH as a key driver of variation inA_a, LT, SD,N_aandN_m. Main ConclusionsOur findings indicate that ontogeny strongly modifies leaf functional traits and that multiple environmental factors influence the magnitude of ontogenetic differences in leaf traits. This underscores the importance of considering ontogeny when predicting trait values across plant developmental stages, modelling vegetation composed of individuals of different ages and forecasting vegetation responses to environmental changes. 

Abstract PremiseClimate change poses challenges to grasslands, including those of the North American Great Plains Region, where shifts in species distributions and fire dynamics are expected. Our present analysis focuses on remaining grasslands within this largely developed and agricultural region. The differential responses of C₄and C₃grass species to future climate conditions, particularly in habitat suitability and flammability, are critical for understanding ecosystem changes. MethodsWe used species distribution models to predict shifts in habitat suitability for 37 grass species under future climate scenarios and assessed flammability traits in a free‐air CO₂‐enrichment study, focusing on species' physiological responses to elevated CO₂, warming, and drought. ResultsOur models predicted that C₄species will retain higher habitat suitability, while C₃species will decline. Leaf‐level flammability analysis showed that species with higher water‐use efficiency under elevated CO will have lower flammability than under non‐elevated, potentially decreasing the predicted rate of fire spread when such species dominate. In contrast, species with higher growth rates but lower water‐use efficiency may be more flammable. Species‐specific responses varied within functional types. Anticipated shifts in species distributions suggest C₄species will become more dominant, potentially altering competitive dynamics and reducing C₃diversity. Changes in flammability under future conditions are expected to influence fire regimes, with a predicted decrease in mean community rate of spread due to the dominance of less‐flammable C₄species. ConclusionsThese findings highlight the need for adaptive fire management and conservation strategies to maintain biodiversity and ecosystem function in North American grasslands under climate change. 

Abstract Invasive wildflowers pose a conservation paradox: While they often reduce the diversity and abundance of native wildflowers, they can provide resources for native pollinators, including imperiled species. Previous work has framed wildflower invasions as outcomes of global change, but less is known about how interacting anthropogenic drivers influence both invasion and pollination. In particular, it remains unclear whether exotic wildflowers compensate for native floral losses under ongoing environmental change. To address this, we tested whether exotic wildflowers provide resources for native pollinators under two drivers of wildflower decline: eutrophication and defaunation. Using a factorial global change experiment at three sites in the highly invaded California floristic region, we tested whether increases in exotic wildflowers (1) sustain pollinator visitation and richness, (2) maintain pollinator composition and function, and (3) facilitate co‐invasion by exotic pollinators. We found that eutrophication promoted exotic asters, which served as visually prominent, attractive hubs in plant–pollinator networks. These asters attracted both generalist and specialist native pollinators but also increased visitation by exotic pollinators, raising the risk of invasional meltdown. Our results suggest that exotic wildflowers can buffer pollinator communities against anthropogenic change but may do so while shifting pollinator composition toward non‐native species. 

Summary Climate change is increasing global temperatures, increasing atmospheric drying, and driving more severe and frequent drought. Plants can cool and humidify microclimates through sensible and latent heat exchange. Higher diversity plant communities can modify microclimates more strongly than lower diversity plant communities, creating the potential for strong biodiversity–climate feedbacks. Here, we review the physical and physiological mechanisms that drive these diversity‐microclimate patterns, catalogue the magnitude of these trends across ecosystem types, and explore how microclimate feedbacks can explain the relationship between biodiversity and ecosystem functioning. We identify key areas where more research is needed (e.g. the role of belowground traits that drive latent heat exchange). This research is essential for understanding how biodiversity and climate are linked at micro‐ and macroscales. 

ABSTRACT Accurate prediction of community assembly is a central goal in ecology but is challenging because assembly is governed by numerous mechanisms. Few theoretical models explicitly incorporate or test multiple mechanisms at once. We empirically tested the predictive performance of a plant community assembly model built using all possible combinations of four ‘mechanisms’ (soil resource competition, dispersal and colonisation, spatiotemporal niche differentiation, population growth rates) and 11 underlying ‘attributes’ based on measured traits (e.g., fecundity, phenology). The full model accurately predicted out‐of‐sample biomass observations of five grasses sown in mixture along a soil nitrogen gradient (overallR² = 0.65). Alternative model variants, parameterised using subsets of the mechanisms and their nested attributes, still retained high explanatory power if the model included at least three of the four mechanisms. Our results suggest that plant community composition is determined by simultaneous effects of multiple mechanisms, and simpler theories have much lower predictive abilities. 

ABSTRACT Global understanding of how plant diversity responds to multiple, co‐occurring global change drivers (e.g., elevated CO₂, climate change, and nitrogen addition) remains fragmented, largely due to the highly context‐dependent nature of responses and disparate experimental evidence. To address this, we conducted a global meta‐analysis synthesising 6832 control‐treatment comparisons from 465 studies. We found that for individual drivers, elevated CO₂had no effect on species richness, whereas increased precipitation enhanced it. In contrast, warming, decreased precipitation, and nitrogen addition generally reduced richness, with nitrogen addition consistently decreasing Shannon diversity and Pielou evenness. When drivers combined, warming‐driven losses were offset by elevated CO₂and increased precipitation and those of nitrogen addition were counteracted by both increased and decreased precipitation. Interaction analyses further revealed that additive effects between drivers predominated, though significant antagonisms emerged for specific pairs. Importantly, these responses were strongly context‐dependent, being mediated by a combination of site‐specific conditions (i.e., local climate, soil, and background diversity) and experimental methodologies (i.e., treatment duration, intensity, and plot and sampling area). Our synthesis underscores that predicting future biodiversity trajectories necessitates that models evolve beyond main effects to explicitly represent both multi‐driver interactions and the critical, often‐dominant, moderating role of local contexts and experimental conditions.