The biodiversity hypothesis links urban species richness to human immunity, yet overlooks habitat heterogeneity that can quarantine pathogenic microbiota. We propose the β-diversity hypothesis: increased tree heterogeneity promotes urban microbial heterogeneity and improve human health. Using plant surveys and paired data of soil, phyllosphere and airborne microbiota transferred indoors (AMTI) across 72 Shanghai neighborhoods, we showed that elevated tree heterogeneity corresponds to higher β-diversity in both AMTI and soil communities. The spatial patterning of respiratory diseases (RDs) was driven by AMTI β-heterogeneity, revealing that homogenization of airborne microbiota affects human respiratory health. We further developed the urban tree βdis model and identified a threshold value of 0.661. Selecting phylogenetically distant tree families, e.g. Arecaceae, Oleaceae and Magnoliaceae at or above this threshold yields ready-to-use planting templates that maintains AMTI β-diversity and a scalable protocol for city-wide greening. Given microbial heterogeneity's emerging health links, our findings call for embedding the β-diversity hypothesis into biodiversity-health frameworks and for cross-biome validation.

Plants affect terrestrial ecosystem functioning by shaping microenvironments1 and by providing the primary production that fuels energy flow into food webs2. However, how plant community properties affect ecosystem functioning via energy fluxes in food webs has been little studied3,4, especially for the soil food webs that channel most plant-derived energy2,5. Applying a food web energetics approach6,7, we show that the resource economics of dominant tree species control soil food web multifunctionality across European forests. Tree communities dominated by resource-acquisitive species promoted faster rates of multiple soil trophic functions than did communities dominated by resource-conservative species. These effects were primarily driven by higher-quality litter and warmer forest microclimates, leading to increased metabolic activity of soil organisms8. Accordingly, tree species composition explained a large portion of variation in soil food web multifunctionality, comparable to that explained by biogeographic differences among locations. By contrast, mixtures of three tree species had weakly negative effects relative to single-species stands, mostly due to shifts in energy channelling from living fine roots to litter and a cooling effect on forest microclimate. This occurred despite an overyielding effect in aboveground tree biomass production, suggesting contrasting diversity effects above- and belowground. Our findings emphasize the importance of plant functional traits related to resource economics as drivers of soil food web functioning5,9 and demonstrate how climate-driven shifts in tree community composition may alter forest soil functioning.

Precipitation change is an important component of the ongoing climate change and substantially influences terrestrial nutrient and carbon (C) dynamics. However, the mechanisms by which increasing precipitation affects plant-microbial nitrogen (N) assimilation and ecosystem C and N retention remain unclear. Using isotopic tracing along a manipulated precipitation gradient in a water- and nutrient-limited alpine ecosystem, we investigated how increasing precipitation alters plant nutrient strategies, plant-microbial N partitioning and ecosystem C and N retention. Increased precipitation enhanced plant and microbial N assimilation, ecosystem N retention and plant C fixation. However, these effects were not consistent across ecosystem components. Increasing precipitation progressively promoted grass-forb ratio and community-level acquisitive root traits, whereas mycorrhizal colonization was greatest at intermediate precipitation. Plant biomass C and N accumulation remained responsive across a broader portion of the precipitation gradient than did microbial N assimilation, thereby shifting plant-microbial N partitioning. Structural equation modelling indicated that the plant pathway plays a stronger role than the microbial pathway in mediating the effects of increasing precipitation on ecosystem N retention and C fixation. Our findings suggest that ecosystem responses to increasing precipitation depend on how different biotic components respond and interact. Synthesis: Increasing precipitation reshapes plant-microbial nutrient partitioning and ecosystem C and N retention in alpine ecosystems. Our findings highlight the need to account for non-linear and contrasting responses among different ecosystem components when predicting the consequences of future climate change for alpine ecosystem functioning. This work contributes to providing a basis for tracking how alpine ecosystems may reorganize under future climate change.

Aim: Climate change affects Arctic vegetation directly through increasing temperatures and indirectly through changes in nutrient availability. Here, we tested the long-term effects of nitrogen (N) and phosphorus (P) additions on tundra plant communities across an elevational gradient. We aimed to explore the interactive effects of nutrient addition, elevation-associated changes in temperature and vegetation type for plant community dynamics in tundra landscapes. Location: Abisko, northern Sweden. Methods: We measured plant community properties in a 14-year-long fully factorial N and P addition experiment in subarctic heath and meadow at three elevations. We used linear mixed effects models and non-metric multidimensional scaling to analyse the main and interactive effects of nutrient addition treatments, vegetation type and elevation over time on community responses. Results: Plant community properties often responded to the interactions between N addition, P addition, vegetation type, elevation and time. Nitrogen was the main limiting nutrient, but N added with P generated the greatest change in plant community composition over time. Community responses to nutrient additions were largely driven by an increase in the abundance of graminoids and a decrease in species richness. The greatest change in plant community composition and species richness occurred in heath at the lower elevation and in the meadow at higher elevations, and the responses of species richness to N and N + P addition became stronger after 7 years. Conclusions: Our results show that significant and relatively fast context (vegetation type and elevation) dependent responses of plant communities to increased N and P availability persist, but in several instances become stronger with time. They highlight the need to account for drivers of spatial and temporal variability in plant community dynamics when predicting plant community and diversity patterns under changes in climate and nutrient supply in tundra landscapes.

Functional traits allow ecologists to synthesise general rules of community assembly. In joint species distribution modelling, traits are increasingly used to explain species-environment relationships, with the intention of being able to generalise predictions to other species in other systems. However, recent studies have challenged the transferability of trait-based species distribution models across systems, by showing that not all trait-environment relationships are broadly applicable. There is therefore a need to reassess the utility of functional traits by examining when trait-based models can be generalised and when they cannot. Using a dataset of tropical post-agricultural secondary forests of two different land-use histories ('abandoned-land forests' in Singapore, where former plantations were abandoned with the plantation trees still standing, and 'waste-woodlands', where trees were clear-cut before the land was abandoned), we analysed the abundances of 80 woody-plant species in 97 plots as a function of trait-environment interactions. To quantify model transferability, we split the dataset into factorial combinations of native versus exotic species and the two land-use histories, cross-validated them against one another, and then examined their prediction accuracies against the environmental and trait dissimilarities between datasets. We found that models trained with native species and/or abandoned-land forests generally transferred well onto exotic species and/or waste-woodlands, as native species and abandoned-land forests encompassed broader, better sampled environmental and trait spaces. In contrast, the reverse transfers had less accurate predictions due to both environmental and trait dissimilarities, which led to disparate trait-environment coefficients. These findings suggest that species (not necessarily native) and more heterogeneous systems that span wider trait and environmental ranges are useful for building predictive models of biological invasions. More broadly, our study demonstrates that some ecological groups or systems yield more general insights than others, so it is crucial to identify the bounds within which each trait-environment relationship operates.

One of the key ecological processes affected by climate change is plant carbon uptake. However, there is substantial uncertainty about how plant carbon uptake will respond to warming in mountain ecosystems, which are known for sharp temperature gradients and abrupt shifts in vegetation structure. Specifically, we lack an understanding of whether these response trajectories over time will be linear or non-linear, and how they might vary among mountain ecosystems globally. Here, we measured ecosystem Gross Primary Productivity (GPP) along forest-tundra elevational gradients in the mountain regions of five countries (Argentina, Australia, France, Sweden, USA) to infer future trajectories of carbon uptake, and whether any non-linear changes might occur. We also examined the role of microclimate in driving GPP responses. We found that whole-ecosystem GPP increased with increasing macroclimatic temperature (decreasing elevation), but this response was dominated by a sharp non-linear increase at the transition from tundra to forest (i.e., the treeline). In contrast, ground-layer GPP was largely independent of macroclimate, but often responded strongly, and linearly, to microclimate (growing degree days > 5°C, mean growing season temperature). This pattern reflected a frequent decoupling of microclimate from the expected temperature-elevation relationship, likely driven by such processes as cold-air drainage, limited near-surface air mixing, and shading by trees. The contrasting responses of GPP among global temperature gradients indicates strong context dependence at both local and continental scales, although in a few cases, biomass and leaf nitrogen were important moderators. These findings suggest that future shifts in carbon uptake in mountains will be mainly controlled by tree range expansion. Our results highlight the need to consider species responses on different spatial scales, and to increase representation of undersampled regions to capture the full breadth of ecological responses to climate change.

Phosphorus (P) is one of the most important elements for soil biology and biogeochemistry worldwide. Yet, despite decades of research, important uncertainties persist about the drivers and changes in soil P forms during long-term soil formation. Here, we analyzed topsoils from nine globally distributed retrogressive soil chronosequences aiming to evaluate the relative contribution of key environmental factors (that is, soil age, substrate origin, climate, soil attributes, and vegetation) in explaining the long-term dynamics of primary, occluded, non-occluded, organic, and total P across different terrestrial ecosystems. We found that, rather than soil age, substrate origin was the main driver controlling the fate of different P fractions across contrasting environmental conditions. Moreover, our findings suggest that temporal patterns governing the long-term dynamics of different P forms as soils develop are not consistent among soil chronosequences, which is a result of contrasting environmental conditions, especially substrate origin. We further showed that topsoil total P was the greatest at intermediate soil development stage across the globe. Lastly, our results showed that P fractions were highly correlated with multiple surrogates of ecosystem services, such as carbon sequestration, plant productivity, and biodiversity. Together, our work provides new insights into the natural history of P availability, and further highlights that substrate origin, rather than soil age, is essential to predict changes in P availability in response to physical perturbation and climate change.

Leaching – the release of elements from organic matter through dissolution in water – plays an important role in biogeochemical cycling and ecosystem processes. However, our limited understanding of the patterns and underlying drivers of element solubility in leaves hinders accurate predictions of leaching over space and time in terrestrial ecosystems. In this study, we quantify the solubility of carbon (C), nitrogen (N) and phosphorus (P) from leaves of Betula pubescens – a widespread boreal tree species – across a post‐fire retrogressive chronosequence. We then relate solubility to variation in leaf‐level traits and ecosystem properties (e.g. soil chemistry, tree density and productivity) across the chronosequence to quantify micro‐ and macro‐scale determinants of leaching. We find that P is much more soluble than C and N and is released in solution mainly in readily accessible mineral form. Solubility patterns are strongly related to foliar chemical and structural traits, particularly for green leaves. Metrics related to ecosystem properties exert a stronger influence over solubility from senesced leaf litter. Overall, our results indicate that leaching could constitute an important flux of nutrients to the soil, particularly for P. The rate and spatio‐temporal pattern of this leaching flux may be predicted from foliar traits and ecosystem properties. Further application of the method should allow for rapid integration of leaching‐related foliar traits into broader plant trait frameworks and models of ecosystem biogeochemical cycling.

There has been much recent interest in understanding how abiotic factors such as light, nutrients, and soil moisture affect the composition and biomass of lichen communities. Meanwhile, whether and how ground layer vegetation such as bryophytes and shrubs also influence lichen communities have received much less attention, particularly regarding how these effects vary across environmental gradients. In this study, we used a long‐term (19‐year) biodiversity manipulation experiment to assess the importance of feather moss and ericaceous dwarf shrub removals on the composition and diversity (assessed via metabarcoding) and biomass (assessed via PLFA markers) of terricolous lichen communities along a 5000‐year boreal forest post‐fire chronosequence in northern Sweden. Overall, our results showed that shrub removals had a greater impact than moss removals on the biomass and composition of lichen communities. Shrub removals increased lichen alpha‐diversity while decreasing lichen beta‐diversity. This is mainly because, although the number of lichen species increased in the absence of shrubs, lichen communities were strongly dominated by Cladonia spp. However, the effects of shrub removals were context‐dependent, with greater effects observed in older ecosystems. Our results highlight that shrubs had a greater impact than moss in shaping terricolous lichen communities in boreal forests, with increasing effects from young ecosystems to older ones. We conclude that the foreseen expansion of vascular plants such as ericaceous shrubs into high latitude regions will probably have negative consequences on lichen cover, but that these effects will be dependent on the environmental context.

Climate change is expected to increase the frequency of severe droughts, but it remains unclear whether soil biotic conditioning by plant communities with varying species richness or functional group diversity moderate plant-soil feedback (PSF)-an important ecosystem process driving plant community dynamics-under altered rainfall regimes. We conducted a two-phase PSF experiment to test how plant diversity affects biotic PSF under different rainfall regimes. In Phase 1, we set up mesocosms with 15 plant assemblages composed of two grasses, two forbs and two nitrogen-fixing legumes [one, two, three, or six species from one, two, or three functional group(s)] common to the semi-arid eastern Eurasian Steppe. Mesocosms were subjected to two rainfall amounts (ambient, 50% reduction) crossed with two frequencies (ambient, 50% reduction) for a growing season (~3 months). Conditioned soil from each mesocosm was then used in Phase 2 to inoculate (7% v/v) sterilised mesocosms planted with the same species as in Phase 1 and grown for 8 weeks. Simultaneously, the same plant assemblages were grown in sterilised soil to calculate PSF based on plant biomass measured at the end of Phase 2. Feedback effects differed amongst plant assemblages, but were not significantly altered by reduced rainfall treatments within any plant assemblage. This suggests that the examined interactions between plant and soil microbial communities were resistant to simulated rainfall reductions and that increasing plant diversity did not moderate PSF under altered rainfall regimes. Moreover, increasing plant species richness or functional group diversity did not lessen the magnitude of PSF differences between ambient and reduced rainfall treatments. Collectively, these findings advance our understanding of plant diversity's potential to mitigate climate change effects on PSF, showing that in semi-arid grasslands, higher plant diversity may not moderate PSF responses to altered rainfall regimes and highlighting the importance of considering species-specific traits and interaction stability.

Human land use intensification is increasing biodiversity loss worldwide through fragmenting contiguous natural habitats into spatially isolated patches of varying sizes. However, it is poorly known as to how the area and isolation of patches operate to jointly alter biological community composition for contrasting land use types, particularly for belowground organisms. Oceanic islands that vary in human activities provide an ideal model system for examining how patch area and isolation affects community dissimilarity resulting from land use change. We conducted a paired sampling design that included both natural woodland (i.e. land covered with woody plants, including trees and shrubs) and degraded grassland for each of 20 islands differing in area and remoteness in the largest archipelago of Eastern China. We used this design to investigate how island area and remoteness shape the community dissimilarity of soil fauna between woodland and grassland directly and indirectly through changing climatic and habitat properties. The dissimilarity of soil fauna communities for each island was estimated by measuring total beta (R) diversity and its turnover and nestedness components between woodland and grassland. We found that land use change did not decrease taxa richness but did alter community composition overall. There was no relationship of island area with community dissimilarity when it was estimated by total R-diversity, due to contrasting responses of its turnover and nestedness components to island area. Soil faunal compositional dissimilarity between woodland and grassland along the area gradient was mainly related to the gain and loss of unique taxa in grassland. On small islands, nestedness was the primary contributor to total R-diversity, due to a loss of soil fauna taxa as habitats shifted from woodland to grassland, and suggests that natural habitats serve as refuges for soil organisms. Meanwhile on larger islands, turnover was the main contributor to total R-diversity, suggesting that diverse land uses can increase biodiversity across habitats. Additionally, high habitat differences combined with favorable climatic conditions (such as low wind speed) on larger islands facilitated species turnover but diminished nestedness. Meanwhile island remoteness did not affect total R-diversity or its components, but it did significantly enhance the negative impact of land-use conversion on the abundance of larger-bodied taxa. These findings suggest that island area, and therefore landscape patch area, play a crucial role in shaping the dissimilarity of soil faunal communities that stem from human land use change. Our results highlight that partitioning total R-diversity into its turnover and nestedness components is essential for understanding the impact of land use change on soil faunal community composition in fragmented habitats.

Plants affect terrestrial ecosystem functioning by performing the primary production that energetically sustains heterotrophic organisms, and by shaping the microenvironment. However, the influence of plant diversity and community composition on ecosystem functioning through their effects on energy flow into food webs has been little studied, especially for soil food webs that channel most of the plant-derived energy. Applying a food web energetics approach, we show that the resource economics of dominant tree species control soil food web multifunctionality across European forests. Specifically, tree communities dominated by resource acquisitive species promoted faster rates of multiple soil trophic functions simultaneously than did those dominated by resource conservative species. This was primarily driven by their production of plant litter with higher nutritional quality and their warmer forest microclimate, leading to a higher metabolic activity of soil organisms. Tree species mixing had rather weak and negative effects on soil food web multifunctionality, mostly due to a shift in the resource-based energy channeling from living plant fine roots to litter and a cooling effect on the forest microclimate. Tree diversity effects were largely outweighed by community compositional effects, which were of similar magnitude to the effects of biogeographic differences among locations. Our findings emphasize the importance of plant functional traits related to resource economics as drivers of plant community effects on soil food web functioning5,9 and highlight the consequences that climate-driven shifts in tree community composition could have for forest soil functioning. ### Competing Interest Statement The authors have declared no competing interest.

Soil bacterial and fungal communities play fundamental roles in biogeochemical cycles and ecosystem stability. Urbanization alters soil properties and microbial habitats, driving shifts in community composition, yet the divergent responses of bacteria and fungi and their ecological consequences remain inadequately understood. To elucidate these differential responses, we investigated soil bacterial and fungal communities along an urbanization gradient, ranging from undisturbed reference forests to urban parks, across three distinct climatic regions. To capture different disturbance intensities, urban parks were classified by tree age into old parks (>60-year-old trees) and young parks (10–20-year-old trees). Climate had a strong influence on soil microbiota, yet urbanization still significantly altered both bacterial and fungal communities in all regions. Urban disturbances homogenized soil microbial communities: average similarity among bacterial communities increased from ∼79 % in forests to ∼85 % in young urban parks, indicating substantial homogenization, whereas fungal communities showed little homogenization. Urbanization also homogenized microbial functional traits, with a greater reduction in trait dissimilarity for bacteria than for fungi. Bacterial communities exhibited high adjustability to urban conditions, dominated by generalist taxa (∼90 %), whereas fungal communities consisted mostly of specialists (∼83 %). Despite these asynchronous responses—bacteria adjusting and homogenizing more than fungi—overlapping functional traits between bacteria and fungi help maintain functional resilience in urban ecosystems.

Nutrient cycling through leaf litter consumption is an essential ecological function performed by macrodetritivorous invertebrates such as isopods and millipedes. Leaf litter consumption rates can vary greatly depending on the environment, consumer identity and litter traits, but generalizations about the effects of plant traits on macrodetritivore leaf litter consumption, assimilation and growth are not well established and are mostly indirectly inferred. We conducted a systematic search of the global literature and obtained 456 standardized measures from laboratory experiments of relative consumption (RCR), assimilation (RAR) and growth (RGR) rates of terrestrial isopods and millipedes, extracted from 56 different articles. We investigated if commonly measured leaf traits, plant functional groups, prior microbial conditioning of leaves and climatic conditions affected these rates. We obtained data on commonly measured leaf traits from the TRY global plant trait database, inferred plant functional groups from taxonomic groupings and obtained climatic data from information reported within articles. RCR, RAR and RGR varied greatly among macrodetritivore and plant species, but overall, there were no differences between isopods and millipedes. Microbial conditioning of litter greatly increased RCR. Plant functional group was an important predictor of RCR, with eudicot trees and forbs being consumed in greater quantities than magnoliid trees and grasses. Fresh leaf N:P ratio had a positive effect on RAR, and leaf N and C:N ratio had positive and negative effects on RGR, respectively, while climatic variables had weak effects on the three rates. Our work shows that plant traits (both those associated with plant functional groups and commonly measured leaf traits) exert strong effects on resource processing rates by terrestrial macrodetritivores. Further, prior microbial conditioning of leaf litter has a large and globally consistent positive effect on macrodetritivore litter consumption, suggesting that they may consume little, if any, freshly senesced leaf material when microbially conditioned litter is available. Our results suggest that, where extremes of temperature or precipitation do not occur, variables reflective of food quality (leaf traits and microbe conditioning) are more important drivers of macrodetritivore leaf litter consumption than are extrinsic climatic variables.Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog.image

Global warming is changing plant communities due to the arrival of new species from warmer regions and declining abundance of cold-adapted species. However, experimentally testing predictions about trajectories and rates of community change is challenging because we normally lack an expectation for future community composition, and most warming experiments fail to incorporate colonization by novel species. To address these issues, we analyzed data from 44 whole-community transplant experiments along 22 elevational gradients across the Northern Hemisphere. In these experiments, high-elevation communities were transplanted to lower elevations to simulate warming, while also removing dispersal barriers for lower-elevation species to establish. We quantified the extent and pace at which warmed high-elevation communities shifted towards the taxonomic composition of lower elevation communities. High-elevation plant communities converged towards the composition of low-elevation communities, with higher rates under stronger experimental warming. Strong community shifts occurred in the first year after transplantation then slowed over time, such that communities remained distinct from both origin and destination control by the end of the experimental periods (3-9 years). Changes were driven to a similar extent by both new species colonization and abundance shifts of high-elevation species, but with substantial variation across experiments that could be partly explained by the magnitude and duration of experimental warming, plot size and functional traits. Our macroecological approach reveals that while warmed high-elevation communities increasingly resemble communities at lower elevations today, the slow pace of taxonomic shifts implies considerable colonization and extinction lags, where a novel taxonomic composition of both low- and high-elevation species could coexist for long periods of time. The important contribution of the colonizing species to community change also indicates that once dispersal barriers are overcome, warmed high-elevation communities are vulnerable to encroachment from lower elevation species.

Boreal forests are frequently subjected to disturbances, including wildfire and clear-cutting. While these disturbances can cause soil carbon (C) losses, the long-term accumulation dynamics of soil C stocks during subsequent stand development is controlled by biological processes related to the balance of net primary production (NPP) and outputs via heterotrophic respiration and leaching, many of which remain poorly understood. We review the biological processes suggested to influence soil C accumulation in boreal forests. Our review indicates that median C accumulation rates following wildfire and clear-cutting are similar (0.15 and 0.20 Mg ha-1 year-1, respectively), however, variation between studies is extremely high. Further, while many individual studies show linear increases in soil C stocks through time after disturbance, there are indications that C stock recovery is fastest early to mid-succession (e.g. 15-80 years) and then slows as forests mature (e.g. >100 years). We indicate that the rapid build-up of soil C in younger stands appears not only driven by higher plant production, but also by a high rate of mycorrhizal hyphal production, and mycorrhizal suppression of saprotrophs. As stands mature, the balance between reductions in plant and mycorrhizal production, increasing plant litter recalcitrance, and ectomycorrhizal decomposers and saprotrophs have been highlighted as key controls on soil C accumulation rates. While some of these controls appear well understood (e.g. temporal patterns in NPP, changes in aboveground litter quality), many others remain research frontiers. Notably, very little data exists describing and comparing successional patterns of root production, mycorrhizal functional traits, mycorrhizal-saprotroph interactions, or C outputs via heterotrophic respiration and dissolved organic C following different disturbances. We argue that these less frequently described controls require attention, as they will be key not only for understanding ecosystem C balances, but also for representing these dynamics more accurately in soil organic C and Earth system models.

Understanding the mechanisms promoting resilience in plant communities is crucial in times of increasing disturbance and global environmental change. Here, we present the first meta-analysis evaluating the relationship between functional diversity and resilience of plant communities. Specifically, we tested whether the resilience of plant communities is positively correlated with interspecific trait variation (following the niche complementarity hypothesis) and the dominance of acquisitive and small-size species (following the mass ratio hypothesis), and for the context-dependent effects of ecological and methodological differences across studies. Global. 2004–2021. Vascular plants. We compiled a dataset of 69 independent sites from 26 studies that have quantified resilience. For each site, we calculated functional diversity indices based on the floristic composition and functional traits of the plant community (obtained from the TRY database) which we correlated with resilience of biomass and floristic composition. After transforming correlation coefficients to Fisher's Z -scores, we conducted a hierarchical meta-analysis, using a multilevel random-effects model that accounted for the non-independence of multiple effect sizes and the effects of ecological and methodological moderators. In general, we found no positive functional diversity–resilience relationships of grand mean effect sizes. In contrast to our expectations, we encountered a negative relationship between resilience and trait variety, especially in woody ecosystems, whereas there was a positive relationship between resilience and the dominance of acquisitive species in herbaceous ecosystems. Finally, the functional diversity–resilience relationships were strongly affected by both ecological (biome and disturbance properties) and methodological (temporal scale, study design and resilience metric) characteristics. We rejected our hypothesis of a general positive functional diversity–resilience relationship. In addition to strong context dependency, we propose that idiosyncratic effects of single resident species present in the communities before the disturbances and biological legacies could play major roles in the resilience of terrestrial plant communities.

Urbanisation, as a global driver of change, modifies the natural environment with well-known consequences to biological communities. Under natural conditions, vegetation drives soil processes in concert with the soil microbial community in their rhizosphere. It remains unclear whether and how vegetation influences these communities in heavily disturbed urban systems where many ecosystem services are also strictly linked to soils and their biota. Here, we used amplicon sequencing and GeoChip arrays to study soil microbiota responses to urbanisation and tree functional types across climatic zones. Our data show that soil microbial communities vary widely across biomes, yet urban parks have compositionally unique microbial communities that are distinct from semi-natural forests. Neither functional trait richness nor functional gene relative abundances responded clearly to urbanization or vegetation type. Despite functional redundancy, vegetation type did affect soil communities compositionally. Soils under trees producing recalcitrant litter had a higher richness of fungal species than the labile ones, whereas lawns, despite of their structural simplicity, had an unexpectedly high diversity of bacteria and fungi. In summary, despite distinct differences in the soil microbiota across biomes, urbanisation and vegetation type have similar effects on structuring microbial communities within biomes. However, the urban soil microbiota, irrespective of the plant functional type they associate with, are functionally comparable to those in semi-natural forests, suggesting functional redundancy within this unique microbiota.

Invasive plants are a growing ecological problem worldwide, but biases and patterns within invasive plant research may affect our understanding of invasive plant ecology. In this study, we analyzed 458 invasive plant papers sampled from the two journals dedicated entirely to the field of invasion biology, i.e., Biological Invasions and Neobiota. From these papers, we collected information on geographic coverage, climate, habitat, taxonomic coverage, plant functional type, and research topic to examine trends across a 21-year time period from 1999 to 2020. Our analysis found that invasive plant research was consistently biased toward temperate grassland and forest ecosystems particularly within the Americas, Europe, and Australia, and toward smaller, herbaceous invasive plant species (i.e., forbs, grasses, and shrubs), with an increase in interest in invasive nitrogen-fixing legumes over time. Our analysis also identified "hot " research topics in invasive plant research at specific time periods, such as a peak in the use of genetic analysis methods in 2014-2015 and a more recent focus on plant physiological and functional traits. While current models, concepts, and understanding of plant invasion ecology are still driven by such biases, this has been partially offset by recent increased research in understudied systems, as well as increasing awareness that plant invasion is heavily affected by their growth types, physiological traits, and soil interactions. As the field of invasion biology becomes ever increasingly important over time, focusing invasive plant research on understudied ecosystems and plant groups will allow us to develop a more holistic understanding of the ecology of invasive plants. In particular, given the outsized importance of the tropics to global biodiversity, the threats they face, and the dearth of studies, it is of critical importance that more invasive plant research is conducted within the tropics to develop a more globally representative understanding of invasive plant ecology.