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A significant challenge for understanding how fungal communities may change in the Anthropocene are the multiple aspects of simultaneous environmental change. To address this challenge, we used a seven-year multi-factorial field experiment in southern California to examine how root-associated fungi respond to aridity, nitrogen deposition, and plant invasions. We hypothesized that all three global change drivers reduce the abundance of arbuscular mycorrhizal fungi responsible for nutrient uptake (edaphophilic AMF), while increasing the abundance of AMF that colonize roots at high rates (rhizophilic AMF). We found that invasive grasses hosted lower abundances of edaphophilic AMF, and higher abundances of rhizophilic AMF and opportunistically parasitic fungi. Aridity reduced overall AMF abundance while N addition altered the allocation of AMF biomass, increasing root colonization while reducing the density of extraradical hyphae. Overall, these results imply that ongoing global change will alter both the composition of AMF and how these fungi interact with plants.

International audience; To predict the threat of biological invasions to native species, it is critical that we understand how increasing abundance of invasive alien species (IAS) affects native populations and communities. The form of this relationship across taxa and ecosystems is unknown, but is expected to depend strongly on the trophic position of the IAS relative to the native species. Using a global metaanalysis based on 1,258 empirical studies presented in 201 scientific publications, we assessed the shape, direction, and strength of native responses to increasing invader abundance. We also tested how native responses varied with relative trophic position and for responses at the population vs. community levels. As IAS abundance increased, native populations declined nonlinearly by 20%, on average, and community metrics declined linearly by 25%. When at higher trophic levels, invaders tended to cause a strong, nonlinear decline in native populations and communities, with the greatest impacts occurring at low invader abundance. In contrast, invaders at the same trophic level tended to cause a linear decline in native populations and communities, while invaders at lower trophic levels had no consistent impacts. At the community level, increasing invader abundance had significantly larger effects on species evenness and diversity than on species richness. Our results show that native responses to invasion depend critically on invasive species’ abundance and trophic position. Further, these general abundance–impact relationships reveal how IAS impacts are likely to develop during the invasion process and when to best manage them.

Worldwide, increasing severity of droughts threatens to change forest ecosystem functioning and community structure. Understanding how forest resilience is determined by its two underlying components, resistance and recovery, will help elucidate the mechanisms of drought responses and help inform management strategies. However, drought responses are shaped by complex processes across different scales, including species-specific drought strategies, tree size, competition, local environmental conditions, and the intensity of the drought event. Here, we quantified the reduction in tree growth during drought (an inverse measure of drought resistance) and post-drought recovery for three montane conifers (Abies concolor, Pinus jeffreyi, and Pinus lambertiana) in California. We used tree ring analysis to quantify responses to drought events of varying intensity between 1895 and 2018 across a geographic climatic gradient, to examine the roles of tree size (DBH) and competition (tree density) in mediating drought responses. We found that years of more intense drought corresponded with larger growth reductions and recovery rates were lower following drought years where trees suffered larger reductions. We found little variation among species in their growth reductions during drought events, but significant differences among species in their recovery post-drought. Across the geographic gradient, trees in the driest locations were susceptible to large growth reductions, signaling either strong sensitivity to drought intensity or exposure to the most extreme drought conditions. These growth reductions were not always compensated for by higher recovery rates. We also found that larger trees were more susceptible to drought due to a steeper negative relationship between recovery rates and the intensity of growth reduction during the drought. Contrary to expectations, recovery rates following the most detrimental drought years were higher in denser forests. Our results demonstrate the importance of considering how factors at various spatial and temporal scales affect the different components of drought responses.

Climate and competition interact to affect species' performance, such as growth and survival, and help determine species distributions and coexistence. However, it is unclear how climatic conditions modulate frequency-dependent performance, that is, how performance changes as a species becomes locally rare or common. This is critical because declines in performance as a species becomes more common (negative frequency dependence) is a signature of niche differences among species that stabilize coexistence, whereas positive frequency dependence leads to priority effects and hampers species coexistence. Here, we used dendrochronology and hierarchical models to test whether frequency-dependent growth of sugar pine (Pinus lambertiana) depends on climatic conditions. We found that growth rates were strongly dependent on annual precipitation, but no frequency dependence was evident across all years. However, there was a strong interaction between precipitation and frequency dependence, revealing stabilizing niche differences in dry years but positive frequency dependence in wet years. These differences emerged because of precipitation-driven changes in the direction and strength of both con- and heterospecific competition. Overall, these results show how stabilizing and destabilizing effects can be temporally dynamic for long-lived species and interact with climate variation.

Germination strategies are critically important for the survival, establishment and spread of plant species. Although many plant traits related to invasiveness have been broadly studied, the earliest part of the life cycle, germination, has received relatively little attention. Here, we compared the germination patterns between native (North America) and introduced (China) populations of Plantagovirginica for four consecutive years to examine whether there has been adaptive differentiation in germination traits and how these traits are related to local climatic conditions. We found that the introduced populations of P.virginica had significantly higher germination percentages and faster and shorter durations of germination than native populations. Critically, the native populations had a significantly larger proportion of seeds that stayed dormant in all four years, with only 60% of seeds germinating in year 1 (compared to >95% in introduced populations). These results demonstrate striking differences in germination strategies between native and introduced populations which may contribute to their successful invasion. Moreover, the germination strategy of P.virginica in their native range exhibited clear geographical variation across populations, with trends towards higher germination percentages at higher latitudes and lower annual mean temperatures and annual precipitation. In the introduced range, however, their germination strategies were more conserved, with less variation amongst populations, suggesting that P.virginica may have experienced strong selection for earlier life history characteristics. Our findings highlight the need to examine the role of rapid evolution of germination traits in facilitating plant invasion.

The niche dimension hypothesis predicts that more species can coexist given a greater number of niche axes along which they partition the environment. Although this hypothesis has been broadly supported by nutrient enrichment experiments, its applicability to other ecological factors, such as natural enemies and abiotic stresses, has not been vigorously tested. Here, we examined the generality of the niche dimension hypothesis by experimentally manipulating both resource and non-resource niche dimensions—nitrogen limitation, pathogens and low-temperature stress—in a Tibetan alpine meadow. We found that decreases in niche dimensions led to a significant reduction in species richness, consistent with results from nutrient addition studies. However, different niche variables uniquely affected the plant communities. While nitrogen had largest effects on both community biomass and species richness, pathogens and low-temperature stress, in combination with nitrogen, had synergistic effects on them. Our results provide direct evidence demonstrating that both resource and non-resource niche dimensions can influence species coexistence. These findings suggest that other non-resource factors need to be taken into consideration to better predict the community assembly and control over biodiversity, particularly under the future multifaceted global change scenarios.

Many plant and animal species are changing their latitudinal and/or altitudinal distributions in response to climate change, but whether fungi show similar changes is largely unknown. Here, we use historical fungal fruit body records from the European Alps to assess altitudinal changes in fungal fruiting between 1960 and 2010. We observe that many fungal species are fruiting at significantly higher elevations in 2010 compared to 1960, and especially so among soil-dwelling fungi. Wood-decay fungi, being dependent on the presence of one or a few host trees, show a slower response. Species growing at higher elevations changed their altitudinal fruiting patterns significantly more than lowland species. Environmental changes in high altitudes may lead to proportionally stronger responses, since high-altitude species live closer to their physiological limit. These aboveground changes in fruiting patterns probably mirror corresponding shifts in belowground fungal communities, suggesting parallel shifts in important ecosystem functions.

International audience; Global climate and land use change are causing woody plant encroachment in arctic, alpine, and arid/semi-arid ecosystems around the world, yet our understanding of the belowground impacts of this phenomenon is limited. We conducted a globally distributed field study of 13 alpine sites across four continents undergoing woody plant encroachment and sampled soils from both woody encroached and nearby herbaceous plant community types. We found that woody plant encroachment influenced soil microbial richness and community composition across sites based on multiple factors including woody plant traits, site level climate, and abiotic soil conditions. In particular, root symbiont type was a key determinant of belowground effects, as Nitrogen-fixing woody plants had higher soil fungal richness, while Ecto/Ericoid mycorrhizal species had higher soil bacterial richness and symbiont types had distinct soil microbial community composition. Woody plant leaf traits indirectly influenced soil microbes through their impact on soil abiotic conditions, primarily soil pH and C:N ratios. Finally, site-level climate affected the overall magnitude and direction of woody plant influence, as soil fungal and bacterial richness were either higher or lower in woody encroached versus herbaceous soils depending on mean annual temperature and precipitation. All together, these results document global impacts of woody plant encroachment on soil microbial communities, but highlight that multiple biotic and abiotic pathways must be considered to scale up globally from site- and species-level patterns. Considering both the aboveground and belowground effects of woody encroachment will be critical to predict future changes in alpine ecosystem structure and function and subsequent feedbacks to the global climate system. © 2020 John Wiley & Sons Ltd

Thermal melanism theory states that dark-colored ectotherm organisms are at an advantage at low temperature due to increased warming. This theory is generally supported for ectotherm animals, however, the function of colors in the fungal kingdom is largely unknown. Here, we test whether the color lightness of mushroom assemblages is related to climate using a dataset of 3.2 million observations of 3,054 species across Europe. Consistent with the thermal melanism theory, mushroom assemblages are significantly darker in areas with cold climates. We further show differences in color phenotype between fungal lifestyles and a lifestyle differentiated response to seasonality. These results indicate a more complex ecological role of mushroom colors and suggest functions beyond thermal adaption. Because fungi play a crucial role in terrestrial carbon and nutrient cycles, understanding the links between the thermal environment, functional coloration and species’ geographical distributions will be critical in predicting ecosystem responses to global warming., The functions of color in fungi are not well characterized. Here, Krah and colleagues investigate the color of mushroom assemblages across Europe and show relationships with climate, nutritional mode (saprotrophic and ectomycorrhizal) and seasonality.

Mismatches between species distributions and their optimal habitat are predicted by ecological theory and will affect species responses to changing climate. However, empirical tests lack consensus on the prevalence of such mismatches and their underlying mechanisms. Here we present a conceptual framework to quantify the mismatch between optimal conditions for species occurrence and multiple measures of population and individual performance (density, adult growth and survival, and recruitment) and the associated performance reduction, or cost. We quantified these mismatches for 59 tree species in the western US along a soil water balance gradient and found high variability in mismatches among species and among performance measures, often resulting in high costs. We used functional traits to explore how dispersal limitation, migration lags, and competitive exclusion may cause mismatches. Overall, the large variability in mismatches, their costs and the relationship with functional traits highlight the nuanced relationships between species' performance and their distributions.

Summary Analogous to the spread of non-native species, shifts in native species’ ranges resulting from climate and land use change are also creating new combinations of species in many ecosystems. These native range shifts may be facilitated by similar mechanisms that provide advantages for non-native species and may also have comparable impacts on the ecosystems they invade. Soil biota, in particular bacteria and fungi, are important regulators of plant community composition and below-ground ecosystem function. Compared to non-native plant invasions, there have been relatively few studies examining how soil biota influence – or are influenced by – native species range shifts. Here, we examined how a native range-expanding sagebrush species (Artemisia rothrockii) affects below-ground abiotic conditions and microbial community structure and function using next-generation sequencing coupled with other biotic and abiotic soil analyses. We utilized a range-expansion gradient, together with a shrub removal experiment and structural equation models, to determine the direct and indirect drivers of these interconnected processes. Sagebrush colonization increased bacterial and archaeal richness and diversity and altered community composition across the expansion gradient. Soil organic C and N and soil moisture increased with sagebrush presence; however, results varied across the expansion gradient. We found no relationship between sagebrush and soil pH; however, pH strongly influenced microbial richness and diversity. Microbial (substrate-induced) respiration was influenced by soil organic N, as well as microbial diversity and functional group relative abundances, highlighting direct and indirect effects of sagebrush on microbial community structure and function. Microbial community composition of soils after 4 years of sagebrush removal was more similar to communities in shrub interspaces than underneath shrubs, suggesting microbial community resilience. Synthesis. Our results suggest that native range expansions can have important impacts on soil biological communities, soil chemistry and hydrology which can further impact below-ground ecosystem processes such as nutrient cycling and litter decomposition. The combination of high-throughput sequencing and structural equation modelling used here offers an exciting yet underutilized approach to understanding how both native and non-native species’ range expansions may affect the structure and function of soil ecosystems.

For much of the twentieth century, many or most scholarly journals in biodiversity, ecology, biogeography and conservation were owned and published by scientific societies and made available to the broader scientific community at relatively low cost. However, the past several decades have seen a dominant process of commercialization of the publication process in this field, either by commercial publishing firms taking over publication of journals owned by a society (e.g., Evolution), or by commercial publishers starting new journals to fill “niches” that were until then empty in the scholarly publishing ecosystem. Diversity and Distributions is an example of this latter category of journals, having been created by Wiley Publishers in 1993 (as Biodiversity Letters). Being a journal owned by a commercial publisher, it has always been accessed by readers via subscription, but the publication process has been free to potential authors whose work has passed peer review.

Global climate and land use change are altering plant and soil microbial communities worldwide, particularly in arctic and alpine biomes where warming is accelerated. The widespread expansion of woody shrubs into historically herbaceous alpine plant zones is likely to interact with climate to affect soil microbial community structure and function, however our understanding of alpine soil ecology remains limited. This study aimed to 1) determine whether the diversity and community composition of soil fungi vary across elevation gradients and to 2) assess the impact of woody shrub expansion on these patterns. In the White Mountains of California, sagebrush (Artemisia rothrockii) shrubs have been expanding upwards into alpine areas since 1960. In this study, we combined observational field data with a manipulative shrub removal experiment along an elevation transect of alpine shrub expansion. We utilized next generation sequencing of the ITS1 region for fungi and joint distribution modeling to tease apart effects of the environment and intra-community interactions on soil fungi. We found that soil fungal diversity declines and community composition changes with increasing elevation. Both abiotic factors (primarily soil moisture and soil organic C) and woody sagebrush range expansion had significant effects on these patterns. However, fungal diversity and relative abundance had high spatial variation, overwhelming the predictive power of vegetation type, elevation, and abiotic soil conditions at the landscape scale. Finally, we observed positive and negative associations among fungal taxa which may be important in structuring community responses to environmental change.

Mushrooms are amongst the most important of non-timber forest products, with growing economic value in many rural areas of the Mediterranean region. At the same time, the effects of climate variability on fungal ecology and productivity are insufficiently understood, because the belowground life cycle of fungi is mediated in many different ways and observational field surveys at the community level are generally too short. Here, we assess records of 48, 348 mycorrhizal and saprotrophic fungal fruit bodies that were recorded at weekly intervals between 1995 and 2013 in Pinar Grande, the largest Spanish Scots pine forest. Autumnal fruiting was delayed by one week after 2004 compared with the period before, the mean annual number of sporocarps dropped from 2 880 to 2 045, and mean species richness declined from 55 to 51. Trends in the phenology and productivity of Boletus edulis and Lactarius spp., the most profitable edible species, were associated with decreasing Jul.–Sep. precipitation totals, whereas the mean fruit body weight of B. edulis significantly increased from 71 to 123 g (pre and post 2004). In tandem with declining Spanish tree growth and truffle harvest since the 1970s, this study reveals a strong dependency of drought-prone Iberian forest ecosystem productivity on hydroclimatic variability. In light of a predicted drier Mediterranean climate, our results further emphasize the importance of long and well-replicated field inventories at high spatiotemporal resolution for informing forest service and management strategies, as well as gastronomy and tourist industries.

Climate change is known to affect regional weather patterns and phenology; however, we lack understanding of how climate drives phenological change across local spatial gradients. This spatial variation is critical for determining whether subpopulations and metacommunities are changing in unison or diverging in phenology. Divergent responses could reduce synchrony both within species (disrupting gene flow among subpopulations) and among species (disrupting interspecific interactions in communities). We also lack understanding of phenological change in environments where life history events are frequently aseasonal, such as the tropical, arid, and semi-arid ecosystems that cover vast areas. Using a 33-year-long dataset spanning a 1,267-m semi-arid elevational gradient in the southwestern United States, we test whether flowering phenology diverged among subpopulations within species and among five communities comprising 590 species. Applying circular statistics to test for changes in year-round flowering, we show flowering has become earlier for all communities except at the highest elevations. However, flowering times shifted at different rates across elevations likely because of elevation-specific changes in temperature and precipitation, indicating diverging phenologies of neighboring communities. Subpopulations of individual species also diverged at mid-elevation but converged in phenology at high elevation. These changes in flowering phenology among communities and subpopulations are undetectable when data are pooled across the gradient. Furthermore, we show that nonlinear changes in flowering times over the 33-year record are obscured by traditional calculations of long-term trends. These findings reveal greater spatiotemporal complexity in phenological responses than previously recognized and indicate climate is driving phenological reshuffling across local spatial gradients.

Fire is a critical ecosystem process that has played a key role in shaping forests throughout the Beartooth Mountains in northwestern Wyoming. The highly variable topography of the area provides ideal conditions to compare fire regimes across contiguous forest types, yet pyro-dendrochronological research in this area is limited. We reconstructed fire frequency, tree age structure, and post-fire tree growth response in the Clarks Fork Ranger District of the Shoshone National Forest to infer variations in historical fire behavior and stand effects. We collected fire-scarred trees and plot-based tree ages on plots ranging 0.5-5 km2 in size across two forest types separated by 2 km: a lower-elevation forest of mixed Douglas-fir and lodgepole pine and a higher elevation treeline forest dominated by whitebark pine. Fires occurred in the lower-elevation forest in 1664, 1706, 1785, 1804, 1846, and 1900 with a mean fire return interval of 47 years. The fires in 1804 and 1900 were also recorded in the higher elevation forest, with significant tree mortality at high elevation in the 1900 fire. Both forests were multi-aged with little evidence of tree cohorts in response to severe, stand-replacing events. On average, tree growth increased after fires, with mean ring widths after fire 39% wider in Douglas-fir and 40% wider in lodgepole pine than pre-fire averages, suggesting that some tree mortality likely occurred in association with lower-elevation forest fires. Burns were more frequent in the lower-elevation forest and were occasionally able to spread into the upper-elevation whitebark stand. Although we suspect the transition of fires from low-to high-elevation occurred during drier years, we did not find any relationship between fire years and available climatic reconstructions via superposed epoch analysis. Regeneration during the 20th Century in the whitebark forest documents recovery of this forest after the 1900 moderate-severity fire event. Finally, especially in the lower-elevation Douglas-fir forest, the period since the last recorded fire (1900) appears to be longer than any fire-free period in the historical record, suggesting that fire exclusion may be creating changes in landscape and patch-scale stand structures, which will likely impact future fire behavior, especially the extent of crown-replacing fire, in these forests.

Aim Analysing how species niches shift between native and introduced ranges is a powerful tool for understanding the determinants of species distributions and for anticipating range expansions by invasive species. Most studies only consider the climatic niche, by correlating widely available presence-only data with regional climate. However, habitat characteristics and disturbance also shape species niches, thereby potentially confounding shifts attributed only to differences in climate. Here we used presence and abundance data for Oxalis pes-caprae, a species native to South Africa and invading areas globally, to understand how niche shifts may be influenced by disturbance at habitat and landscape scales in addition to climate. Locality Mediterranean climate areas world-wide. Methods We used available presence-only data and also conducted extensive surveys of the abundance of Oxalis (c. 11,000 plots) across different habitats in South Africa and in the introduced range in the Mediterranean Basin. We extended principal component analysis methods for measuring niche shifts by using Bayesian generalized linear models to identify climatic and disturbance niche shifts. Results We found a large climatic niche expansion towards stronger seasonality and lower temperature in the introduced range, but this expansion was greatly reduced when considering only conditions available in both ranges. Oxalis occupied more natural landscapes in the native range that remained unoccupied in the introduced range (‘niche unfilling’). In contrast to the similar abundances in natural and disturbed habitats in its native range, Oxalis was more abundant in disturbed habitats in the introduced range. Conclusions The large climatic niche expansion most likely reflects significant plasticity of Oxalis rather than rapid evolution. Furthermore, the unfilling of its disturbance niche in the introduced range suggests high potential for further invasion of natural areas. Together, these findings suggest that the potential for future spread of invasive species may be underestimated by approaches that characterize species niches based only on climate or partial information about their distributions.

Aim Understanding the conditions that promote biological invasions is a critical step to developing successful management strategies. However, the level of invasion is affected by complex interactions among environmental factors that might change across habitats and regions making broad generalizations uninformative for management. We aimed to quantify the context-dependent association of climate and human activity at landscape scale (i.e. disturbance and propagule pressure) with the level of plant invasion at local scale across different stages of invasion, habitat types and bioclimatic regions. Location Mainland Spain. Methods Based on an extensive database of vegetation plots (~50,000), we used hierarchical Bayesian models to test how climate and human activity at a landscape scale (i.e. land-cover variables) are associated with establishment (i.e. presence) and dominance (i.e. relative species richness and abundance in invaded plots) of non-native plants across nine habitat types and three bioclimatic regions. Results The association of climate with establishment and dominance of nonnative plants varied depending on habitat type but not bioclimatic region. These associations also varied depending on the stage of invasion under consideration. Establishment of non-native species was more likely close to the coast, while their dominance increased in wet and warm continental areas. Human activity variables were associated with establishment and dominance similarly across bioclimatic regions. Non-native species establishment and abundance peaked in human-altered landscapes. Different habitats showed different susceptibilities to establishment versus dominance by non-native species (e.g. woodlands had medium levels of establishment, but very low dominance). Main conclusions This study highlights how complex interactions among climate, human activity and habitats can determine patterns of invasions across broad landscapes. Successful management of plant invasions will depend on understanding these context-dependent effects across habitats at the different stages of the invasion process.

Summary 1. Mismatches between species distributions and habitat suitability are predicted by niche theory and have important implications for forecasting how species may respond to environmental changes. Quantifying these mismatches is challenging, however, due to the high dimensionality of species niches and the large spatial and temporal variability in population dynamics. 2. Here, we explore how probabilistic assessments of habitat suitability based on demographic models may be used to better bridge niche theory and population dynamics. We use integral projection models (IPMs) to predict population growth rates for a terrestrial orchid in response to environmental variables. By parameterizing these IPMs with hierarchical models, we develop a spatially variable measure of a species’ demographic niche, which can then be compared against its distribution to test ideas about what factors control a species’ distribution. 3. We found that demographic suitability of sites was not well correlated with the orchid’s distribution at local scales, with many absences from microsites of high predicted suitability and occurrences in sites with low predicted suitability. However, at the population scale, abundance was positively correlated with demographic suitability of the sites. These results are consistent with dispersal limitation and source–sink dynamics at small scales but stronger distribution-suitability matching at larger landscape scales. 4. Synthesis. The relationships between species distributions and demographic performance underlie basic niche theory and have important implications for predicting responses to a changing environment. The complexities of these relationships will require approaches that can encapsulate what we know in probabilistic terms and allow for spatially varying niche relationships.

Despite the critical importance of fungi as symbionts with plants, resources for animals, and drivers of ecosystem function, the spatiotemporal distributions of fungi remain poorly understood. The belowground life cycle of fungi makes it difficult to assess spatial patterns and dynamic processes even with recent molecular techniques. Here we offer an explicit spatiotemporal Bayesian inference of the drivers behind spatial distributions from investigation of a Swiss inventory of fungal fruit bodies. The unique inventory includes three temperate forest sites in which a total of 73 952 fungal fruit bodies were recorded systematically in a spatially explicit design between 1992 and 2006. Our motivation is to understand how broad-scale climate factors may influence spatiotemporal dynamics of fungal fruiting within forests, and if any such effects vary between two functional groups, ectomycorrhizal (ECM) and saprotrophic fungi. For both groups we asked: 1) how consistent are the locations of fruiting patches, the sizes of patches, the quantities of fruit bodies, and of prevalence (occupancy)? 2) Do the annual spatial characteristics of fungal fruiting change systematically over time? 3) Are spatial characteristics of fungal fruiting driven by climatic variation? We found high inter-annual continuity in fruiting for both functional groups. The saprotrophic species were characterised by small patches with variable fruit body counts. In contrast, ECM species were present in larger, but more distinctly delimited patches. The spatial characteristics of the fungal community were only indirectly influenced by climate. However, climate variability influenced overall yields and prevalence, which again links to spatial structure of fruit bodies. Both yield and prevalence were correlated with the amplitudes of occurrence and of fruit body counts, but only prevalence influenced the spatial range. Summarizing, climatic variability affects forest-stand fungal distributions via its influence on yield (amount) and prevalence (occupancy), whereas fungal life-history strategies dictate fine-scale spatial characteristics

Species occurrence observations are increasingly available for scientific analyses through citizen science projects and digitization of museum records, representing a largely untapped ecological resource. When combined with open-source data, there is unparalleled potential for understanding many aspects of the ecology and biogeography of organisms. Here we describe the process of assembling a pan-European mycological meta-database (ClimFun) and integrating it with open-source data to advance the fields of macroecology and biogeography against a backdrop of global change. Initially 7.3 million unique fungal species fruit body records, spanning nine countries, were processed and assembled into 6 million records of more than 10,000 species. This is an extraordinary amount of fungal data to address macro-ecological questions. We provide two examples of fungal species with different life histories, one ectomycorrhizal and one wood decaying, to demonstrate how such continental-scale meta-databases can offer unique insights into climate change effects on fungal phenology and fruiting patterns in recent decades.

Summary 1. Patterns of forest biodiversity are shaped by a complex set of processes operating over different spatial scales. Climate may largely determine species richness at regional scales, but biotic interactions and disturbance events are known to be important at local scales. The interactions between these local and regional processes are poorly understood, complicating efforts to manage for biodiversity. 2. In this study, we used Spanish forest inventory data, together with hierarchical Bayesian models, to analyse how different harvest intensities affect patterns of species richness in a 152 000 km 2 area in central Spain. Particularly, we quantified the interacting effects of locally applied silvicultural disturbances, of those applied in the surrounding landscape, and of the regional climate on native tree species richness. 3. Our study supports the overall hypothesis that a hierarchical set of processes influence species richness, with regional climate contributing to shape the impacts of local harvesting practices and other environmental variables (topography and productivity). 4. In particular, we found that partial harvesting in both coniferous and broad-leaved Mediterranean forests may support greater tree species richness than complete harvesting and no management. However, this effect depended on the ecosystem and the surrounding landscape, being much less likely in semi-arid regions under water stress conditions and in landscapes dominated by managed forests (and particularly by completely harvested stands). 5. In general, forest stands exhibited increased tree species richness when surrounded by species-rich riparian forests, probably due to metacommunity dynamics and/or ecological history (land uses) of the area. 6. Synthesis and applications. The effects of forest management on local species richness were shaped by coarse climate conditions and by the type and extent of other management practices in the surrounding landscapes. Therefore, to develop effective forestry management plans that optimize local diversity, we need to (i) apply regionally tailored practices with lower harvest intensities in areas of greater hydric stress; (ii) avoid the extensive application of a single silvicultural system over large areas and (iii) preserve a mosaic of species-rich forests that can act as sources of colonizers to enrich the regenerating stands nearby.

© 2016 Elmendorf et al. Phenology is an integrative science that comprises the study of recurring biological activities or events. In an era of rapidly changing climate, the relationship between the timing of those events and environmental cues such as temperature, snowmelt, water availability, or day length are of particular interest. This article provides an overview of the observer-based plant phenology sampling conducted by the U.S. National Ecological Observatory Network (NEON), the resulting data, and the rationale behind the design. Trained technicians will conduct regular in situ observations of plant phenology at all terrestrial NEON sites for the 30-yr life of the observatory. Standardized and coordinated data across the network of sites can be used to quantify the direction and magnitude of the relationships between phenology and environmental forcings, as well as the degree to which these relationships vary among sites, among species, among phenophases, and through time. Vegetation at NEON sites will also be monitored with tower-based cameras, satellite remote sensing, and annual high-resolution airborne remote sensing. Ground-based measurements can be used to calibrate and improve satellite-derived phenometrics. NEON's phenology monitoring design is complementary to existing phenology research efforts and citizen science initiatives throughout the world and will produce interoperable data. By collocating plant phenology observations with a suite of additional meteorological, biophysical, and ecological measurements (e.g., climate, carbon flux, plant productivity, population dynamics of consumers) at 47 terrestrial sites, the NEON design will enable continental-scale inference about the status, trends, causes, and ecological consequences of phenological change.

Climate change and biological invasions are primary threats to global biodiversity that may interact in the future. To date, the hypothesis that climate change will favour non-native species has been examined exclusively through local comparisons of single or few species. Here, we take a meta-analytical approach to broadly evaluate whether non-native species are poised to respond more positively than native species to future climatic conditions. We compiled a database of studies in aquatic and terrestrial ecosystems that reported performance measures of non-native (157 species) and co-occurring native species (204 species) under different temperature, CO(2) and precipitation conditions. Our analyses revealed that in terrestrial (primarily plant) systems, native and non-native species responded similarly to environmental changes. By contrast, in aquatic (primarily animal) systems, increases in temperature and CO(2) largely inhibited native species. There was a general trend towards stronger responses among non-native species, including enhanced positive responses to more favourable conditions and stronger negative responses to less favourable conditions. As climate change proceeds, aquatic systems may be particularly vulnerable to invasion. Across systems, there could be a higher risk of invasion at sites becoming more climatically hospitable, whereas sites shifting towards harsher conditions may become more resistant to invasions.

Extreme climatic events (ECEs) – such as unusual heat waves, hurricanes, floods, and droughts – can dramatically affect ecological and evolutionary processes, and these events are projected to become more frequent and more intense with ongoing climate change. However, the implications of ECEs for biological invasions remain poorly understood. Using concepts and empirical evidence from invasion ecology, we identify mechanisms by which ECEs may influence the invasion process, from initial introduction through establishment and spread. We summarize how ECEs can enhance invasions by promoting the transport of propagules into new regions, by decreasing the resistance of native communities to establishment, and also sometimes by putting existing non-native species at a competitive disadvantage. Finally, we outline priority research areas and management approaches for anticipating future risks of unwanted invasions following ECEs. Given predicted increases in both ECE occurrence and rates of species introductions around the globe during the coming decades, there is an urgent need to understand how these two processes interact to affect ecosystem composition and functioning.

Shifts in species phenology in response to climate change have wide-ranging consequences for ecological systems. However, significant variability in species responses, together with limited data, frustrates efforts to forecast the consequences of ongoing phenological changes. Herein, we use a case study of three North American plant communities to explore the implications of variability across levels of organisation (within and among species, and among communities) for forecasting responses to climate change. We show how despite significant variation among species in sensitivities to climate, comparable patterns emerge at the community level once regional climate drivers are accounted for. However, communities differ with respect to projected patterns of divergence and overlap among their species phenological distributions in response to climate change. These analyses and a review of hypotheses suggest how explicit consideration of spatial scale and levels of biological organisation may help to understand and forecast phenological responses to climate change.

Many non-native plants in the US have become problematic invaders of native and managed ecosystems, but a new generation of invasive species may be at our doorstep. Here, we review trends in the horticultural trade and invasion patterns of previously introduced species and show that novel species introductions from emerging horticultural trade partners are likely to rapidly increase invasion risk. At the same time, climate change and water restrictions are increasing demand for new types of species adapted to warm and dry environments. This confluence of forces could expose the US to a range of new invasive species, including many from tropical and semiarid Africa as well as the Middle East. Risk assessment strategies have proven successful elsewhere at identifying and preventing invasions, although some modifications are needed to address emerging threats. Now is the time to implement horticulture import screening measures to prevent this new wave of plant invasions.

The strength and direction of phenological responses to changes in climate have been shown to vary significantly both among species and among populations of a species, with the overall patterns not fully resolved. Here, we studied the temporal and spatial variability associated with the response of several insect species to recent global warming. We use hierarchical models within a model comparison framework to analyze phenological data gathered over 40 years by the Japan Meteorological Agency on the emergence dates of 14 insect species at sites across Japan. Contrary to what has been predicted with global warming, temporal trends of annual emergence showed a later emergence day for some species and sites over time, even though temperatures are warming. However, when emergence data were analyzed as a function of temperature and precipitation, the overall response pointed out an earlier emergence day with warmer conditions. The apparent contradiction between the response to temperature and trends over time indicates that other factors, such as declining populations, may be affecting the date phenological events are being recorded. Overall, the responses by insects were weaker than those found for plants in previous work over the same time period in these ecosystems, suggesting the potential for ecological mismatches with deleterious effects for both suites of species. And although temperature may be the major driver of species phenology, we should be cautious when analyzing phenological datasets as many other factors may also be contributing to the variability in phenology.

For several hundred years, millions of fungal sporocarps have been collected and deposited in worldwide collections (fungaria) to support fungal taxonomy. Owing to large-scale digitization programs, metadata associated with the records are now becoming publicly available, including information on taxonomy, sampling location, collection date and habitat/substrate information. This metadata, as well as data extracted from the physical fungarium specimens themselves, such as DNA sequences and biochemical characteristics, provide a rich source of information not only for taxonomy but also for other lines of biological inquiry. Here, we highlight and discuss how this information can be used to investigate emerging topics in fungal global change biology and beyond. Fungarium data are a prime source of knowledge on fungal distributions and richness patterns, and for assessing red-listed and invasive species. Information on collection dates has been used to investigate shifts in fungal distributions as well as phenology of sporocarp emergence in response to climate change. In addition to providing material for taxonomy and systematics, DNA sequences derived from the physical specimens provide information about fungal demography, dispersal patterns, and are emerging as a source of genomic data. As DNA analysis technologies develop further, the importance of fungarium specimens as easily accessible sources of information will likely continue to grow.This article is part of the theme issue ‘Biological collections for understanding biodiversity in the Anthropocene’.

The enemy release hypothesis is a common explanation for species invasions, suggesting that introduced species benefit from leaving behind natural enemies in the native range. However, any such advantage may attenuate over time. In this study, we test a prediction of this more dynamic enemy release hypothesis: that non-native plant species that became established longer ago exhibit stronger negative feedbacks with the soil. Consistent with declining enemy release over time, we found increasingly negative soil feedbacks for species established longer ago in New Zealand. Negative soil feedbacks were also stronger for more widespread species, but weaker for more locally abundant species, suggesting that species accumulate negative interactions as they spread and can be locally regulated by these interactions. We also present data to support the common assumption that relatives have similar impacts on and responses to soil communities. Together, these data highlight the dynamic nature of novel interactions arising from species introductions.

Despite their high abundance, secondary production, and known reliance on detrital material, the role of chironomids (Diptera) in fine particulate organic matter (FPOM) dynamics has not been well quantified. We conducted field trials using fluorescent pigment markers to estimate seasonal rates of consumption, annual secondary production, assimilation efficiency (AE), and FPOM turnover for non-Tanypodinae chironomids in two similar, southern Appalachian, headwater streams. An ecosystem-level experimental manipulation of detrital inputs in one study stream allowed for a unique assessment of turnover in reference, resource-limited, and resource-recovery systems. Seasonality had a significant effect on larval gut-passage time (GPT), with faster GPT at higher temperatures. Mean GPT ranged from 39 min (summer) to 67 min (winter). Mean annual FPOM turnover was reduced in the resource-limited stream (5.5 kg ash-free dry weight per year; 12% of mean annual FPOM export) compared to the reference stream (46 kg yr21 ;7 4% of mean export). Following 4 yr of resource recovery, FPOM turnover increased to 24 kg ash-free dry wt yr21 (16% of export) but remained lower than levels measured in the reference stream (53 kg ash-free dry wt yr21 ;2 0% of export). Chironomid contribution to FPOM turnover was much higher in low vs. high discharge conditions (74% in low discharge vs. 20% in high discharge). Assimilation efficiency was estimated to be low in all systems (1.7–2.5%). Chironomids turned over a large portion of FPOM available to them, suggesting that turnover by the entire collector community in forested headwater systems may be much higher than expected.

Summary 1. The distribution and abundance of invasive species can be driven by both environmental variables and land management decisions. However, understanding these relationships can be complicated by interactions between management actions and environmental variability, and differences in scale among these variables. The resulting ‘context-dependence’ of management actions may be well-appreciated by ecologists and land managers, but can frustrate attempts to apply general management principles. 2. In this study, we quantify the effects of land management and environmental variability at different scales on the occurrence and abundance of Hieracium pilosella, a major agricultural weed in New Zealand. We used a hierarchical study design and analysis to capture relevant scales of variation in management actions and environmental heterogeneity, and test hypotheses about how these factors interact. 3. We show that fertilizing and grazing interact with environmental gradients at the scale of management application (farm paddocks) to influence the establishment and local abundance of H. pilosella. 4. We further show that H. pilosella’s relationships with fine-scale abiotic and biotic factors are consistent with expected mechanisms driven by larger-scale management actions. Using data on occurrence and local abundance, we tease apart which factors are important to establishment and subsequent local spread. 5. Synthesis and applications. A major challenge for environmental scientists is to predict how invasive species may respond to ongoing landscape modifications and environmental change. This effort will require approaches to study design and analysis that can accommodate complexities such as interacting management and environmental variables at different scales. Management actions will be more likely to succeed when they explicitly account for variation in environmental context.

Our understanding of broad taxonomic patterns of plant naturalizations is based entirely on observations of successful naturalizations. Omission of the failures, however, can introduce bias by conflating the probabilities of introduction and naturalization. Here, we use two comprehensive datasets of successful and failed plant naturalizations in New Zealand and Australia for a unique, flora-wide comparative test of several major invasion hypotheses. First, we show that some taxa are consistently more successful at naturalizing in these two countries, despite their environmental differences. Broad climatic origins helped to explain some of the differences in success rates in the two countries. We further show that species with native relatives were generally more successful in both countries, contrary to Darwin's naturalization hypothesis, but this effect was inconsistent among families across the two countries. Finally, we show that contrary to studies based on successful naturalizations only, islands need not be inherently more invisible than continents.

Darwin acknowledged contrasting, plausible arguments for how species invasions are influenced by phylogenetic relatedness to the native community. These contrasting arguments persist today without clear resolution. Using data on the naturalization and abundance of exotic plants in the Auckland region, we show how different expectations can be accommodated through attention to scale, assumptions about niche overlap, and stage of invasion. Probability of naturalization was positively related to the number of native species in a genus but negatively related to native congener abundance, suggesting the importance of both niche availability and biotic resistance. Once naturalized, however, exotic abundance was not related to the number of native congeners, but positively related to native congener abundance. Changing the scale of analysis altered this outcome: within habitats exotic abundance was negatively related to native congener abundance, implying that native and exotic species respond similarly to broad scale environmental variation across habitats, with biotic resistance occurring within habitats.

Climate change will likely reshuffle ecological communities, causing novel species interactions that could profoundly influence how populations and communities respond to changing conditions. Nonetheless, predicting the impacts of novel interactions is challenging, partly because many methods of inference are contingent on the current configuration of climatic variables and species distributions. Focusing on competition, we argue that experiments designed to quantify novel interactions in ways that can inform species distribution models are urgently needed, and suggest an empirical agenda to pursue this goal, illustrated using plants. An emerging convergence of ideas from macroecology and demographically focused competition theory offers opportunities to mechanistically incorporate competition into species distribution models, while forging closer ties between experimental ecology and macroecology.

Abiotic and biotic processes operate at multiple spatial and temporal scales to shape many ecological processes, including species distributions and demography. Current debate about the relative roles of niche-based and stochastic processes in shaping species distributions and community composition reflects, in part, the challenge of understanding how these processes interact across scales. Traditional statistical models that ignore autocorrelation and spatial hierarchies can result in misidentification of important ecological covariates. Here, we demonstrate the utility of a hierarchical modeling framework for testing hypotheses about the importance of abiotic factors at different spatial scales and local spatial autocorrelation for shaping species distributions and abundances. For the two orchid species studied, understory light availability and soil moisture helped to explain patterns of presence and abundance at a microsite scale (

A fundamental challenge to understanding patterns in ecological systems lies in employing methods that can analyse, test and draw inference from measured associations between variables across scales. Hierarchical linear models (HLM) use advanced estimation algorithms to measure regression relationships and variance-covariance parameters in hierarchically structured data. Although hierarchical models have occasionally been used in the analysis of ecological data, their full potential to describe scales of association, diagnose variance explained, and to partition uncertainty has not been employed. In this paper we argue that the use of the HLM framework can enable significantly improved inference about ecological processes across levels of organization. After briefly describing the principals behind HLM, we give two examples that demonstrate a protocol for building hierarchical models and answering questions about the relationships between variables at multiple scales. The first example employs maximum likelihood methods to construct a two-level linear model predicting herbivore damage to a perennial plant at the individual- and patch-scale; the second example uses Bayesian estimation techniques to develop a three-level logistic model of plant flowering probability across individual plants, microsites and populations. HLM model development and diagnostics illustrate the importance of incorporating scale when modelling associations in ecological systems and offer a sophisticated yet accessible method for studies of populations, communities and ecosystems. We suggest that a greater coupling of hierarchical study designs and hierarchical analysis will yield significant insights on how ecological processes operate across scales.

Summary 1 The recruitment stage can be critical in determining plant population dynamics, as juveniles encounter a range of abiotic and biotic stressors in the environments where they land after dispersal, and often experience high mortality rates. Although both abiotic and biotic constraints on recruitment are often assumed to operate at multiple scales, these relationships are rarely quantified in ways that enable prediction of recruitment dynamics across environmental gradients. 2 In plants such as orchids, an important bottleneck on recruitment may arise from an obligate dependence on mycorrhizal fungi in order to reach photosynthetic stage. Very little is known, however, about the factors controlling the distribution of the fungi or how fungal distributions may constrain orchid recruitment and distributions. 3 In this study, seed introduction experiments were used to test for relationships between symbiotic germination success of an orchid, Goodyera pubescens, and both proximity to adult orchids and soil abiotic conditions. Experiments were linked to ongoing demographic monitoring across a large environmental gradient to place patterns of germination better in the context of longer-term demographic patterns. 4 A hierarchical Bayesian statistical framework was used to evaluate explicitly how recruitment varies across scales and how this variation is explained by key abiotic variables. This framework was further utilized to link hypothesis testing to model building, and thereby improve our ability to make predictions across a range of environmental conditions. 5 At a microsite scale (

Migratory species have critical habitat needs during both breeding and wintering portions of the life cycle. Recent advances have made it possible to use satellite imagery and computer-assisted spatial analysis technology along with fieldwork to determine estimates for these critical habitat needs for the endangered Golden-cheeked Warbler, Dendroica chrysoparia. Using these procedures, we estimate that the Ashe juniper–oak breeding habitat for this species covers 6430 km2 of central Texas, USA, whereas appropriate habitat in the known winter range covers 6750 km2 of the Middle American cordillera. When combined with information on warbler breeding and wintering ecology, these figures indicate that the amount of available winter habitat (pine–oak above 1219 m [4000′] in elevation) supports only a fraction (15%) of the population that could be supported by the amount of estimated available breeding habitat, suggesting that Golden-cheeked Warbler populations could be limited by winter habitat availability. C...

Invasive species distributions tend to be biased towards some habitats compared to others due to the combined effects of habitat-specific resistance to invasion and non-uniform propagule pressure. These two factors may also interact, with habitat resistance varying as a function of propagule supply rate. Recruitment experiments, in which the number of individuals recruiting into a population is measured under different propagule supply rates, can help us understand these interactions and quantify habitat resistance to invasion while controlling for variation in propagule supply rate. Here, we constructed recruitment functions for the invasive herb Hieracium lepidulum by sowing seeds at five different densities into six different habitat types in New Zealand's Southern Alps repeated over two successive years, and monitored seedling recruitment and survival over a four year period. We fitted recruitment functions that allowed us to estimate the total number of safe sites available for plants to occupy, which we used as a measure of invasion resistance, and tested several hypotheses concerning how invasion resistance differed among habitats and over time. We found significant differences in levels of H. lepidulum recruitment among habitats, which did not match the species' current distribution in the landscape. Local biotic and abiotic characteristics helped explain some of the between-habitat variation, with vascular plant species richness, vascular plant cover, and light availability, all positively correlated with the number of safe sites for recruitment. Resistance also varied over time however, with cohorts sown in successive years showing different levels of recruitment in some habitats but not others. These results show that recruitment functions can be used to quantify habitat resistance to invasion and to identify potential mechanisms of invasion resistance.

Species’ range dynamics depend not only on their ability to track climate, but also on the migration of their competitors, and the extent to which novel and current competitors exert differing competitive effects. A little studied but important effect of climate change on ecological communities will be how it alters the interactions between species. To study this experimentally, Jake Alexander et al. transplanted plant species and communities along a natural temperature gradient on an elevation gradient in the Swiss Alps. There is an interesting asymmetry in that species do well when moving to keep track with climate even if they encounter a new community of competitors, but they do badly when failing to migrate if a new community moves to join them. Understanding how species respond to climate change is critical for forecasting the future dynamics and distribution of pests, diseases and biological diversity1,2,3. Although ecologists have long acknowledged species’ direct physiological and demographic responses to climate, more recent work suggests that these direct responses can be overwhelmed by indirect effects mediated via other interacting community members2,3,4,5,6,7. Theory suggests that some of the most dramatic impacts of community change will probably arise through the assembly of novel species combinations after asynchronous migrations with climate8,9,10. Empirical tests of this prediction are rare, as existing work focuses on the effects of changing interactions between competitors that co-occur today7,11,12,13,14,15. To explore how species’ responses to climate warming depend on how their competitors migrate to track climate, we transplanted alpine plant species and intact plant communities along a climate gradient in the Swiss Alps. Here we show that when alpine plants were transplanted to warmer climates to simulate a migration failure, their performance was strongly reduced by novel competitors that could migrate upwards from lower elevation; these effects generally exceeded the impact of warming on competition with current competitors. In contrast, when we grew the focal plants under their current climate to simulate climate tracking, a shift in the competitive environment to novel high-elevation competitors had little to no effect. This asymmetry in the importance of changing competitor identity at the leading versus trailing range edges is best explained by the degree of functional similarity between current and novel competitors. We conclude that accounting for novel competitive interactions may be essential to predict species’ responses to climate change accurately.

As the main witnesses of the ecological and economic impacts of invasions on ecosystems around the world, ecologists seek to provide the relevant science that informs managers about the potential for invasion of specific organisms in their region(s) of interest. Yet, the assorted literature that could inform such forecasts is rarely integrated to do so, and further, the diverse nature of the data available complicates synthesis and quantitative prediction. Here we present a set of analytical tools for synthesizing different levels of distributional and/or demographic data to produce meaningful assessments of invasion potential that can guide management at multiple phases of ongoing invasions, from dispersal to colonization to proliferation. We illustrate the utility of data-synthesis and data-model assimilation approaches with case studies of three well-known invasive species--a vine, a marine mussel, and a freshwater crayfish--under current and projected future climatic conditions. Results from the integrated assessments reflect the complexity of the invasion process and show that the most relevant climatic variables can have contrasting effects or operate at different intensities across habitat types. As a consequence, for two of the study species climate trends will increase the likelihood of invasion in some habitats and decrease it in others. Our results identified and quantified both bottlenecks and windows of opportunity for invasion, mainly related to the role of human uses of the landscape or to disruption of the flow of resources. The approach we describe has a high potential to enhance model realism, explanatory insight, and predictive capability, generating information that can inform management decisions and optimize phase-specific prevention and control efforts for a wide range of biological invasions.

Phenological events, such as the timing of flowering or insect emergence, are influenced by a complex combination of climatic and non-climatic factors. Although temperature is generally considered most important, other weather events such as frosts and precipitation events can also influence many species' phenology. Non-climatic variables such as photoperiod and site-specific habitat characteristics can also have important effects on phenology. Forecasting phenological shifts due to climate change requires understanding and quantifying how these multiple factors combine to affect phenology. However, current approaches to analyzing phenological data have a limited ability for quantifying multiple drivers simultaneously. Here, we use a novel statistical approach to estimate the combined effects of multiple variables, including local weather events, on the phenology of several taxa (a tree, an insect, and a fungus). We found that thermal forcing had a significant positive effect on each species, frost events delayed the phenology of the tree and butterfly, and precipitation had a positive effect on fungal fruiting. Using data from sites across latitudinal gradients, we found that these effects are remarkably consistent across sites once latitude and other site effects are accounted for. This consistency suggests an underlying biological response to these variables that is not commonly estimated using data from field observations. This approach's flexibility will be useful for forecasting ongoing phenological responses to changes in climate variability in addition to seasonal trends.

Although striking changes have been documented in plant and animal phenology over the past century, less is known about how the fungal kingdom's phenology has been changing. A few recent studies have documented changes in fungal fruiting in Europe in the last few decades, but the geographic and taxonomic extent of these changes, the mechanisms behind these changes, and their relationships to climate are not well understood. Here, we analyzed herbarium data of 274 species of fungi from Michigan to test the hypotheses that fruiting times of fungi depend on annual climate and that responses depend on taxonomic and functional groups. We show that the fungal community overall fruits later in warmer and drier years, which has led to a shift toward later fruiting dates for autumn-fruiting species, consistent with existing evidence. However, we also show that these effects are highly variable among species and are partly explained by basic life-history characteristics. Resulting differences in climate sensitivities are expected to affect community structure as climate changes. This study provides a unique picture of the climate dependence of fungal phenology in North America and an approach for quantifying how individual species and broader fungal communities will respond to ongoing climate change.

The enemy release hypothesis is a common explanation for species invasions, suggesting that introduced species benefit from leaving behind natural enemies in the native range. However, any such advantage may attenuate over time. In this study, we test a prediction of this more dynamic enemy release hypothesis: that non-native plant species that became established longer ago exhibit stronger negative feedbacks with the soil. Consistent with declining enemy release over time, we found increasingly negative soil feedbacks for species established longer ago in New Zealand. Negative soil feedbacks were also stronger for more widespread species, but weaker for more locally abundant species, suggesting that species accumulate negative interactions as they spread and can be locally regulated by these interactions. We also present data to support the common assumption that relatives have similar impacts on and responses to soil communities. Together, these data highlight the dynamic nature of novel interactions arising from species introductions.