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Aim Organisms on our planet form spatially congruent and functionally distinct communities, which at large geographical scales are called “biomes”. Understanding their pattern and function is vital for sustainable use and protection of biodiversity. Current global terrestrial biome classifications are based primarily on climate characteristics and functional aspects of plant community assembly. These and other existing biome schemes do not take account of soil organisms, including highly diverse and functionally important microbial groups. We aimed to define large-scale structure in the diversity of soil microbes (soil microbiomes), pinpoint the environmental drivers shaping it and identify resemblance and mismatch with existing terrestrial biome schemes. Location Global. Time period Current. Major taxa studied Soil eukaryotes and prokaryotes. Methods We collected soil samples from natural environments world-wide, incorporating most known terrestrial biomes. We used high-throughput sequencing to characterize soil biotic communities and k-means clustering to define soil microbiomes describing the diversity of microbial eukaryotic and prokaryotic groups. We used climatic data and soil variables measured in the field to identify the environmental variables shaping soil microbiome structure. Results We recorded strong correlations among fungal, bacterial, archaeal, plant and animal communities, defined a system of global soil microbiomes (producing seven biome types for microbial eukaryotes and six biome types for prokaryotes) and showed that these are typically structured by pH alongside temperature. None of the soil microbiomes are directly paralleled by any current terrestrial biome scheme, with mismatch most substantial for prokaryotes and for microbial eukaryotes in cold climates; nor do they consistently distinguish grassland and forest ecosystems. Main conclusions Existing terrestrial biome classifications represent a limited surrogate for the large-scale diversi

Arbuscular mycorrhizal (AM) fungi are a ubiquitous group of plant symbionts, yet processes underlying their global assembly — in particular the roles of dispersal limitation and historical drivers — remain poorly understood. Because earlier studies have reported niche conservatism in AM fungi, we hypothesized that variation in taxonomic community composition (i.e., unweighted by taxon relatedness) should resemble variation in phylogenetic community composition (i.e., weighted by taxon relatedness) which reflects ancestral adaptations to historical habitat gradients. Because of the presumed strong dispersal ability of AM fungi, we also anticipated that the large-scale structure of AM fungal communities would track environmental conditions without regional discontinuity. We used recently published AM fungal sequence data (small‐subunit ribosomal RNA gene) from soil samples collected worldwide to reconstruct global patterns in taxonomic and phylogenetic community variation. The taxonomic structure of AM fungal communities was primarily driven by habitat conditions, with limited regional differentiation, and there were two well-supported clusters of communities — occurring in cold and warm conditions. Phylogenetic structure was driven by the same factors, though all relationships were markedly weaker. This suggests that niche conservatism with respect to habitat associations is weakly expressed in AM fungal communities. We conclude that the composition of AM fungal communities tracks major climatic and edaphic gradients, with the effects of dispersal limitation and historic factors considerably less apparent than those of climate and soil.

Classical theory identifies resource competition as the major structuring force of biotic communities and predicts that (i) levels of dominance and richness in communities are inversely related, (ii) narrow niches allow dense “packing” in niche space and thus promote diversity, and (iii) dominants are generalists with wide niches, such that locally abundant taxa also exhibit wide distributions. Current empirical support, however, is mixed. We tested these expectations using published data on arbuscular mycorrhizal (AM) fungal community composition worldwide. We recorded the expected negative relationship between dominance and richness and, to a degree, the positive association between local and global dominance. However, contrary to expectations, dominance was pronounced in communities where more specialists were present and, conversely, richness was higher in communities with more generalists. Thus, resource competition and niche packing appear to be of limited importance in AM fungal community assembly; rather, patterns of dominance and diversity seem more consistent with habitat filtering and stochastic processes.

Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, applied, and assessed standardized protocols to measure tundra herbivory at three spatial scales: plot, site (habitat), and study area (landscape). The plot- and site-level protocols were tested in the field during summers 2014–2015 at 11 sites, nine of them consisting of warming experimental plots included in the International Tundra Experiment (ITEX). The study area protocols were assessed during 2014–2018 at 24 study areas across the Arctic. Our protocols provide comparable and easy to implement methods for assessing the intensity of invertebrate herbivory within ITEX plots and for characterizing vertebrate herbivore communities at larger spatial scales. We discuss methodological constraints and make recommendations for how these protocols can be used and how sampling effort can be optimized to obtain comparable estimates of herbivory, both at ITEX sites and at large landscape scales. The application of these protocols across the tundra biome will allow characterizing and comparing herbivore communities across tundra sites and at ecologically relevant spatial scales, providing an important step towards a better understanding of tundra ecosystem responses to large-scale environmental change.

The arbuscular mycorrhizal (AM) fungi are a globally distributed group of soil organisms that play critical roles in ecosystem function. However, the ecological niches of individual AM fungal taxa are poorly understood. We collected > 300 soil samples from natural ecosystems worldwide and modelled the realised niches of AM fungal virtual taxa (VT; approximately species‐level phylogroups). We found that environmental and spatial variables jointly explained VT distribution worldwide, with temperature and pH being the most important abiotic drivers, and spatial effects generally occurring at local to regional scales. While dispersal limitation could explain some variation in VT distribution, VT relative abundance was almost exclusively driven by environmental variables. Several environmental and spatial effects on VT distribution and relative abundance were correlated with phylogeny, indicating that closely related VT exhibit similar niche optima and widths. Major clades within the Glomeraceae exhibited distinct niche optima, Acaulosporaceae generally had niche optima in low pH and low temperature conditions, and Gigasporaceae generally had niche optima in high precipitation conditions. Identification of the realised niche space occupied by individual and phylogenetic groups of soil microbial taxa provides a basis for building detailed hypotheses about how soil communities respond to gradients and manipulation in ecosystems worldwide.

Background: Herbivores modify the structure and function of tundra ecosystems. Understanding their impacts is necessary to assess the responses of these ecosystems to ongoing environmental changes. However, the effects of herbivores on plants and ecosystem structure and function vary across the Arctic. Strong spatial variation in herbivore effects implies that the results of individual studies on herbivory depend on local conditions, i.e., their ecological context. An important first step in assessing whether generalizable conclusions can be produced is to identify the existing studies and assess how well they cover the underlying environmental conditions across the Arctic. This systematic map aims to identify the ecological contexts in which herbivore impacts on vegetation have been studied in the Arctic. Specifically, the primary question of the systematic map was: “What evidence exists on the effects of herbivores on Arctic vegetation?”. Methods: We used a published systematic map protocol to identify studies addressing the effects of herbivores on Arctic vegetation. We conducted searches for relevant literature in online databases, search engines and specialist websites. Literature was screened to identify eligible studies, defined as reporting primary data on herbivore impacts on Arctic plants and plant communities. We extracted information on variables that describe the ecological context of the studies, from the studies themselves and from geospatial data. We synthesized the findings narratively and created a Shiny App where the coded data are searchable and variables can be visually explored. Review findings: We identified 309 relevant articles with 662 studies (representing different ecological contexts or datasets within the same article). These studies addressed vertebrate herbivory seven times more often than invertebrate herbivory. Geographically, the largest cluster of studies was in Northern Fennoscandia. Warmer and wetter parts of the Arctic had the, Errata: Soininen, E.M., Barrio, I.C., Bjørkås, R. et al. Correction to: Location of studies and evidence of effects of herbivory on Arctic vegetation: a systematic map. Environ Evid 2022;11:20. DOI: 10.1186/s13750-022-00265-z

Anthropogenic impact represents a major pressure on ecosystems, yet little is known about how it affects symbiotic relationships, such as mycorrhizal symbiosis, which plays a crucial role in ecosystem functioning. We analyzed the effects of three human impact types – increasing urbanity, introduction of alien plant species (alienness) and modifications in plant species distribution ranges (as a proxy for naturalness) – on plant community mycorrhization and arbuscular mycorrhization (indicating the degree of forming mycorrhizal symbiosis at plant community level using the relative abundance of mycorrhizal and arbuscular mycorrhizal plants, respectively). The study was carried out in three habitat types, each dominated by a distinct mycorrhizal type – ectomycorrhizal woodlands, ericoid mycorrhizal heathlands and arbuscular mycorrhizal grasslands - at the regional scale in the Netherlands. The response of community mycorrhization and arbuscular mycorrhization to anthropogenic influence showed contrasting patterns, depending on the specific aspect of human impact. Community mycorrhization responded negatively to urbanity and positively to increasing alienness, while arbuscular mycorrhization showed the reverse trend. More natural heathlands were found to be more mycorrhizal and less arbuscular mycorrhizal. The strongest responses were detected in woodlands and heathlands, while mycorrhization in grasslands was relatively insensitive to human impact. Our study highlights the importance of considering mycorrhizal symbiosis in understanding and quantifying the effects of anthropogenic influence on plant communities, especially in woodlands and heathlands.

AimIdentifying the factors that drive large-scale patterns of biotic interaction is fundamental for understanding how communities respond to changing environmental conditions. Mycorrhizal symbiosis is a key interaction between fungi and most vascular plants. Whether plants are obligately (OM) or facultatively (FM) mycorrhizal, and which mycorrhizal type they form – arbuscular mycorrhizal (AM), ectomycorrhizal (ECM), ericoid mycorrhizal (ERM) or non-mycorrhizal (NM) – can have strong implications for plant species distribution at the continental scale and on the responses of plants to environmental gradients.LocationEurope, north of 43° latitude and excluding Russia, Belarus and Moldova.Time periodUndefined.Major taxa studiedVascular plants.MethodsUsing published sources, we compiled the most complete dataset yet of plant mycorrhizal and geographical information for Europe, comprising 1442 plant species. We mapped the European distributions of plant mycorrhizal status (OM and FM) and type (AM, ECM, ERM and NM) and analysed their relationships with climatic, edaphic and plant productivity drivers on a 50 km × 50 km equal-area grid.ResultsThe distribution of mycorrhizal types in Europe was driven by mean temperature, soil pH and productivity. AM plant species predominated throughout the region, but at higher latitudes the share of NM and, to a lesser extent, ECM and ERM species increased. FM species predominated over OM species, and this increased with latitude and was dependent on temperature drivers. The high share of OM species in the central European mountains indicates a possible influence of historical glacial refugia.Main conclusionsOur results challenge the prevailing view of parallel trends in the latitudinal and elevational distribution of mycorrhizal types and demonstrate distinctive responses of plants with different mycorrhizal status to climatic, edaphic and biogeographical drivers at the European scale.