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Distributed experimental networks have emerged as a powerful approach in field ecology, enabling experimental replication across global gradients. These networks use standardized treatments at dispersed sites to identify factors like climate or soil that shape biotic responses. Reserving space for future “add‐on” work fosters discovery by transforming distributed networks into distributed experimental infrastructure. However, challenges include balancing feasibility, plot impacts, and demands on site scientists. Using the Disturbance and Recovery Across Grasslands Network (DRAGNet) as a case study informed by lessons learned in the Nutrient Network (NutNet), we outline effective practices for designing add‐on work to retain the original experiment’s integrity while effectively using the resources of the network participants. By following guidelines for hypothesis‐driven, inclusive research that engages contributors intellectually, minimizes plot impacts using field‐tested protocols, and maximizes scientific impact and inclusion, distributed networks can become valuable infrastructure for advancing ecological understanding. 

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 Global interest and investment in nature‐based solutions (NbS) are rapidly increasing because of the potential of this approach to concurrently counter biodiversity loss, provide cost‐effective measures for climate change adaptations, and maintain natural processes that underpin human health and wellbeing.Recognition is growing that grasslands in many regions will protect carbon stores more effectively than forests in the warmer, drier, more fire‐prone conditions of the future while also serving as hotspots for biodiversity. Yet grasslands have received less attention for their NbS potential. Despite the wide‐ranging goals of this approach, many investments in nature‐based solutions also have focused narrowly on using plants to meet climate pledges, often without considering plant interactions with herbivores and the abiotic environment that jointly control ecosystem functioning and underpin the success of nature‐based solutions.Here, we review the roles that large and small vertebrate and invertebrate herbivores play in the ability of the world's grasslands to provide nature‐based solutions, with a focus on wild herbivore impacts on biodiversity and carbon storage.Synthesis. Planning for nature‐based solutions with a holistic, ecologically informed view that includes the role of herbivores and their interaction with plants and the environment will allow NbS investments to more likely achieve successful, sustainable outcomes. 

ABSTRACT Nutrient enrichment has decreased the diversity and abundance of wildflower species, raising questions about whether nutrient enrichment can further decrease the diversity and abundance of pollinators that rely on wildflowers. Whether the effects of nutrient enrichment on plant–pollinator interactions differ by nutrient type remains an open question. Moreover, plant family and flower color, two core axes of pollination niches, may further mediate how wildflowers and their pollinators respond to nutrient enrichment. We tested these questions using a nutrient addition experiment replicated at three grasslands in California, a global plant diversity hotspot. We found that adding nitrogen increased the floral abundance of Asteraceae, while decreasing that of Fabaceae, Geraniaceae, Iridaceae, and Euphorbiaceae. Adding phosphorus and potassium in the absence of nitrogen produced the opposite effects. Pollinator abundance and composition varied strongly by floral family, suggesting that these differing responses to nutrient addition by floral family may alter pollinator community composition. Nitrogen addition decreased the abundance of native blue, native green, and exotic pink flowers, while increasing the abundance of native and exotic yellow and exotic purple flowers. Consequently, nitrogen addition increased pollinator abundance on purple flowers, while decreasing pollinator abundance on pink flowers. Purple and yellow Asteraceae species, which increased under nitrogen enrichment, acted as core hubs in structuring the plant–pollinator network.Synthesis:Our findings suggest that the type of nutrient, plant family, and flower color modulate how plant–pollinator interactions respond to eutrophication. 

Plants in grasslands navigate a complex landscape of interactions including competition for resources and defense against pathogens. Foliar fungi can suppress plant growth directly through pathogenic interactions, or indirectly via host growth-defense tradeoffs. The exclusion of foliar fungi allows the reallocation of resources from defense to growth and reproduction. In addition, plants also invest photosynthates in rhizodeposition, or root exudates, which play a significant role in shaping the rhizosphere microbial community. However, it remains unclear what impact the exclusion of foliar fungi has on the allocation of resources to rhizodeposition and the composition of the rhizosphere microbial community. Using a 6-year foliar fungicide study in plots planted with 16 species of native prairie plants, we asked whether foliar fungi influence the rhizosphere microbial composition of a common prairie grass (Andropogon gerardii) and a common legume (Lespedeza capatita). We found that foliar fungicide increased aboveground biomass and season-long plant production, but did not alter root biomass, seed production, or rhizosphere microbial diversity. The magnitude of change in aboveground season-long plant production was significantly associated with the magnitude of change in the rhizosphere microbial community in paired foliar fungicide-treatedvs. control plots. These results suggest important coupling between foliar fungal infection and plant investment in rhizodeposition to modify the local soil microbial community. 

Abstract Plant disease often increases with N, decreases with CO₂, and increases as biodiversity is lost (i.e., the dilution effect). Additionally, all these factors can indirectly alter disease by changing host biomass and hence density-dependent disease transmission. Yet over long periods of time as communities undergo compositional changes, these biomass-mediated pathways might fade, intensify, or even reverse in direction. Using a field experiment that has manipulated N, CO₂, and species richness for over 20 years, we compared severity of a specialist rust fungus (Puccinia andropogonis) on its grass host (Andropogon gerardii) shortly after the experiment began (1999) and twenty years later (2019). Between these two sampling periods, two decades apart, we found that disease severity consistently increased with N and decreased with CO₂. However, the relationship between diversity and disease reversed from a dilution effect in 1999 (more severe disease in monocultures) to an amplification effect in 2019 (more severe disease in mixtures). The best explanation for this reversal centered on host density (i.e., aboveground biomass), which was initially highest in monoculture, but became highest in mixtures two decades later. Thus, the diversity-disease pattern reversed, but disease consistently increased with host biomass. These results highlight the consistency of N and CO₂as drivers of plant disease in the Anthropocene and emphasize the critical role of host biomass—despite potentially variable effects of diversity—for relationships between biodiversity and disease. 

Plants serve as critical links between above- and below-ground microbial communitites, both influencing and being influenced by microbes in these two realms. Below-ground microbial communities are expected to respond to soil resource environments, which are mediated by the roots of plants that can, in turn, be influenced by the above-ground community of foliar endophytes. For instance, diverse plant communities deposit more, and more diverse, nutrients into the soil, and this deposition is often increased when foliar pathogens are removed. Differences in soil resources can alter soil microbial composition and phenotypes, including inhibitory capacity, resource use, and antibiotic resistance. In this work, we consider plots differing in plant richness and application of foliar fungicide, evaluating consequences on soil resource levels and root-associatedStreptomycesphenotypes. Soil carbon, nitrogen, phosphorus, potassium, and organic matter were greater in samples from polyculture than monoculture, yet this increase was surprisingly offset when foliar fungal communities were disrupted. We find thatStreptomycesphenotypes varied more between richness plots—with theStreptomycesfrom polyculture showing lower inhibitory capacity, altered resource-use profiles, and greater antibiotic resistance—than between subplots with/without foliar fungicide. Where foliar fungicide affected phenotypes, it did so differently in polyculture than in monoculture, for instance decreasing niche width and overlap in monoculture while increasing them in polyculture. No differences in phenotype were correlated with soil nutrient levels, suggesting the need for further research looking more closely at soil resource diversity and particular compounds that were found to differ between treatments.