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{"Abstract":["The data in this package is associated with the analysis for a manuscript titled\n "Multiple community properties drive ecosystem resistance and resilience to extreme climate\n events across mesic grasslands". The files include compiled data on plant biomass production,\n species abundance, experimental treatments, extreme climate event values, and calculated\n diversity and stability measures from grassland plots in experiments at CDR, KBS, and KNZ LTER\n sites."]} 

Abstract Human activities have increased nitrogen (N) bioavailability broadly, resulting in increased plant productivity and decreased plant species richness globally. However, the determinants of the rates of change and the ultimate plant community composition resulting from N additions remain unclear. Here we synthesize data from six long-term N addition experiments in a tallgrass prairie ecosystem to (1) determine whether plant compositional change with N additions occurs gradually or is an abrupt response, (2) identify short-term (i.e., pulse) environmental drivers that may cause compositional changes, and (3) map the end points of plant communities following a decade or more of N addition. We find that most plant community change occurred gradually over the first several years of chronic N additions, with no evidence that other perturbations (i.e., precipitation, herbivory, fire) catalyzed the change. Rather, we think that the observed pattern reflects the long-lived nature of dominant plant species within this community. Additionally, we find that the final community composition differed across the six experiments we synthesized, seemingly driven by differences in the initial plant community composition. Despite different species coming to dominate the six experiments with N addition, these species shared functional identities as fast-growing, weedy species. The shifts in tallgrass plant community composition observed with increased N availability across the six experiments synthesized here may have consequences for the stability of ecosystem function in a world with altered N bioavailability. Long-term experiments are necessary to capture these responses to N addition, with short-term experiments likely underestimating the community responses to altered N. 

Abstract IntroductionThe removal of clonal and resprouting woody plants expanding into mesic grasslands like tallgrass prairies can be expensive based on the types of treatments applied and subsequent retreatments. ObjectiveWe aimed to determine how combined herbicide application, mechanical treatments, and annual prescribed fire influenced grassland recovery from resprouting woody plants based on topographic locations (lowland, slope, upland) at the Konza Prairie Biological Station near Manhattan, Kansas, USA. MethodsWe assessed tree cover using the Rangeland Analysis Platform and monitored shrub stem densities and plant species composition across different topographic positions (lowland, slope, upland) for 4 years post‐woody plant removal. Specifically, we assessed which herbaceous species recolonized the treated woody plant areas or shrub islands and the stability of the recovering herbaceous community. ResultsFour years after herbicide, mechanical treatments and annual prescribed fire, tree cover remained low in the watershed. Shrub stem densities increased on the slopes and lowlands, but decreased in the uplands. In the lowlands, annual and perennial forb species rapidly colonized former shrub islands, while on the slopes and uplands shrub species maintained cover dominance even though upland stem densities were reduced. ConclusionsThis study shows that 4 years after herbicide and cutting/mowing treatments combined with annual fire, woody plants re‐established in the lowlands more readily than the other topographic positions, and the infilling of perennial grasses into former shrub island locations was not achieved to a desirable cover to be considered dominant. Tracking plant community trajectory could become an important monitoring strategy to verify if a management objective was met for restoring woody encroached grasslands. 

Landscape heterogeneity is widely recognized as a driver of biodiversity, yet its consequences for above‐ground, foliage‐dwelling insect communities under active grassland management remain underexplored. Patch‐burn grazing (PBG), which rotates fire across patches within a grazed landscape, is designed to promote spatial and temporal heterogeneity by creating a shifting mosaic of successional stages. In contrast, annual burning and grazing (ABG) imposes uniform disturbance. We tested how these contrasting strategies shape aboveground invertebrate communities across three years (2021–2023) in tallgrass prairie at the Konza Prairie Biological Station in Manhattan, Kansas. Using vacuum sampling, we quantified family‐level richness, evenness, abundance and functional composition of above‐ground, foliage‐associated insects; this method targets smaller, vegetation‐dwelling taxa. Contrary to expectations, PBG did not consistently enhance local (alpha) or beta‐diversity. Insect richness was higher in ABG in one year, while evenness was greater in PBG in another. Total abundances and functional group distributions were broadly similar, with only limited treatment differences. However, PBG significantly altered invertebrate community composition in two of three years, suggesting that heterogeneity influenced community structuring, even when richness was unchanged. Family composition differed between ABG and PBG in two of three years, driven primarily by higher and more variable Cicadellidae in PBG, with additional contributions from Acrididae, Formicidae, Curculionidae and Caliscelidae. Herbivory rates did not differ between treatments. Our findings reveal that using PBG to manage spatial heterogeneity leads to complex responses in insect communities, but may lead to distinct community compositions across the landscape. This decoupling of richness from composition highlights the importance of considering multiple biodiversity metrics when evaluating ecological outcomes. By fostering compositional variability without inflating herbivore pressure, PBG has potential as a heterogeneity‐based strategy for managing grasslands. 

Abstract Grasslands cover approximately a third of the Earth’s land surface and account for about a third of terrestrial carbon storage. Yet, we lack strong predictive models of grassland plant biomass, the primary source of carbon in grasslands. This lack of predictive ability may arise from the assumption of linear relationships between plant biomass and the environment and an underestimation of interactions of environmental variables. Using data from 116 grasslands on six continents, we show unimodal relationships between plant biomass and ecosystem characteristics, such as mean annual precipitation and soil nitrogen. Further, we found that soil nitrogen and plant diversity interacted in their relationships with plant biomass, such that plant diversity and biomass were positively related at low levels of nitrogen and negatively at elevated levels of nitrogen. Our results show that it is critical to account for the interactive and unimodal relationships between plant biomass and several environmental variables to accurately include plant biomass in global vegetation and carbon models. 

Abstract In our changing world, understanding plant community responses to global change drivers is critical for predicting future ecosystem composition and function. Plant functional traits promise to be a key predictive tool for many ecosystems, including grasslands; however, their use requires both complete plant community and functional trait data. Yet, representation of these data in global databases is sparse, particularly beyond a handful of most used traits and common species. Here we present the CoRRE Trait Data, spanning 17 traits (9 categorical, 8 continuous) anticipated to predict species’ responses to global change for 4,079 vascular plant species across 173 plant families present in 390 grassland experiments from around the world. The dataset contains complete categorical trait records for all 4,079 plant species obtained from a comprehensive literature search, as well as nearly complete coverage (99.97%) of imputed continuous trait values for a subset of 2,927 plant species. These data will shed light on mechanisms underlying population, community, and ecosystem responses to global change in grasslands worldwide. 

The tree diversity–productivity relationship is key to effective forest restoration and management; however, it remains unclear what role foliar chemical diversity and interactions between trees and their enemies play in driving this relationship. Trees produce chemical metabolites in their leaves that impact herbivory and pathogen infection. If trees alter the diversity of metabolites they produce when grown in more diverse communities, this could impact interactions with herbivores and pathogens. Ultimately, these tropic interactions with plant enemies, mediated by chemical diversity, could be important drivers of diversity–productivity relationships. Using a large‐scale tree diversity experiment, we used a focal tree sampling design from 14 species across a gradient of tree species richness to assess the role of foliar chemicals and trophic interactions in the diversity–productivity relationship. We used untargeted metabolomics to measure foliar phytochemical diversity, monitored tree–enemy interactions, including foliar fungal pathogens, caterpillar communities and deer browsing, and modelled their relationship to tree growth using path analysis. We unravelled significant evidence for top‐down mediation of the diversity–productivity relationship driven primarily by herbivores rather than foliar pathogens and contrasting effects of foliar chemical diversity on different enemy types. Individual trees growing in more diverse communities had higher phytochemical diversity and higher caterpillar richness, but lower leaf fungal pathogen richness. Leaf phytochemical diversity was positively associated with caterpillar richness and fungal pathogen richness, but negatively associated with browsing by white‐tailed deer (Odocoileus virginianus). Path analysis revealed that phytochemical diversity, caterpillar richness, insect damage and deer damage—but not foliar pathogens—all mediated positive indirect effects of tree richness on tree growth rate. Synthesis: We highlight the significant mediation of diversity–productivity relationships via contrasting effects of phytochemical diversity on plant–enemy interactions. Ultimately, our study underscores the importance of incorporating trophic interactions into biodiversity–ecosystem function studies. 

Abstract Research internships provide students with invaluable experience conducting independent research, contributing to larger research programs, and embedding in a professional scientific setting. These experiences increase student persistence in ecology and other science, technology, engineering, and mathematics (STEM) fields and promote the inclusion of students who lack opportunities at their home institutions and/or are from groups that are underrepresented in STEM. While many ecology internship programs were canceled during the 2020 COVID‐19 pandemic, others successfully adapted to offer virtual internships for the first time. Though different from what many researchers and students envision when they think of internships, virtual ecology internship programs can create more accessible opportunities and be just as valuable as in‐person opportunities when research programs and advisors develop virtual internships with intention and planning. Here, we highlight six ways to structure a virtual intern project, spanning a spectrum from purely computer‐based opportunities (e.g., digital data gathering, data analysis, or synthesis) to fully hands‐on research (e.g., sample processing or home‐based experiments). We illustrate examples of these virtual projects through a case study of the Smithsonian Environmental Research Center's 2020 Virtual Internship Program. Next, we provide 10 recommendations for effectively developing a virtual internship program. Finally, we end with ways that virtual internships can avoid the limitations of in‐person internships, as well as possible solutions to perceived pitfalls of virtual internships. While virtual internships became a necessity in 2020 due to COVID‐19, the development and continuation of virtual internships in future can be a valuable tool to add to the suite of existing internship opportunities, possibly further promoting diversity, equity, and inclusion in ecology and STEM.