Abstract Plant functional traits driving ecosystem functioning can have either similar or distinct evolutionary histories, meaning that both functional and phylogenetic diversity can jointly influence ecosystem dynamics. However, the relative importance of this relationship depends on the environmental context. In this study, we combined species into assemblages by using a full‐factorial experiment varying low and high levels of functional and phylogenetic diversity. We conducted a diversity‐decomposition assessment along independent gradients of rainfall and landscape disturbance in the seasonally tropical dry forest of the Brazilian Caatinga. We demonstrated that functional diversity, even holding species richness constant at four, promoted decomposition and played a greater role in decomposition than phylogenetic diversity. Equally or more importantly, the extent to which differences in traits and evolutionary lineages affected leaf decomposition was contingent on rainfall and landscape disturbance. Functional diversity increased mass loss, particularly in dry conditions and disturbed landscapes. In contrast, increasing phylogenetic diversity was associated with lower leaf decomposition in dry regions, but this effect reversed in wetter regions. Our experimental findings suggest that ecological gradients likely mediate ecosystem functioning. Furthermore, we identified a potential role of functional diversity as a buffer against climate change and disturbance in dry ecosystems, reinforcing the benefit of biodiversity conservation efforts aimed at protecting as many species and traits as possible.

Anthropogenic nitrogen (N) deposition is a major nutrient input to forests, yet most N addition experiments fall short of mirroring the chronic canopy‐level deposition observed in nature. As a result, we still lack an understanding of how atmospheric N deposition affects overall forest multifunctionality, including trade-offs and synergies among different ecosystem functions. Failure to account for these interactions risks that nutrient-related management strategies unintentionally undermine important functions while promoting others. Here, we integrate national forest inventory data with forest functioning models in a multivariate Bayesian framework to quantify the effect of N deposition on forest multifunctionality derived from 13 individual functions, explicitly accounting for their trade-offs. We identify a consistent negative effect of N deposition on biodiversity conservation-oriented multifunctionality (~95% probability) in both broadleaf and needleleaf forests. Biomass production-oriented multifunctionality shows a positive association with N deposition in broadleaf forests (73% probability), but neutral-to-negative responses in needleleaf forests. Overall and climate regulation-oriented forest multifunctionalities are both likely to decline with increasing N deposition in both forest types (67% – 81% probabilities). Such relationships are largely stable across temperature, precipitation, soil pH, and altitudinal gradients, suggesting broad applicability across climatically analogous temperate (ca. 51.6% of global area) and boreal (ca. 24.4% of global area) forests worldwide. Pervasive trade-offs among individual functions underscore the risk of ignoring inter-dependence that substantially biases estimates of N deposition effects on forest functioning. Our findings highlight the importance of reducing nitrogen emissions, particularly for mitigating biodiversity loss for multifunctional forests.

Although habitat heterogeneity is known to enhance local species diversity, the effects of management-driven structural heterogeneity on understorey plant communities across spatial scales remain poorly understood, despite their crucial role for forest biodiversity and ecosystem functioning. To analyse how forest understorey plant communities respond to an enhancement of structural heterogeneity in managed forests, we established 11 experimental sites consisting of two paired forest landscapes, an untreated homogenous control and a treatment district (ESBC, Enhancement of Structural Beta-Complexity). In treatment districts, structural heterogeneity was enhanced through different combinations of local patch-scale manipulations of light and deadwood features, leading to greater between-patch heterogeneity at the landscape scale. We performed a meta-analysis across these 11 sites using a Hill-Chao number and sample coverage standardisation framework. Gamma diversity increased across taxonomic, functional and phylogenetic facets in structurally heterogeneous forests (ESBC districts) via higher alpha diversity. This effect was positively associated with heterogeneity in light availability between forest patches, but not with their mean light availability. In contrast, we found no evidence supporting that species turnover among patches (i.e. beta diversity) significantly contributes on average to the observed increase in gamma diversity. However, both the direction and magnitude of beta diversity responses varied substantially among study sites. On average, structurally heterogeneous forests supported higher species richness for both open and closed forest habitat species. Synthesis and applications. Our findings highlight the benefits of enhancing structural heterogeneity for understorey plant diversity in managed forest landscapes. Specifically, management strategies that create a spatial mosaic of interventions, such as combining single-tree removal with gap felling, can increase the variety of light niches among forest patches, thereby supporting the conservation of a wide range of understorey plant species, including forest specialists.

Forests provide a wide range of ecosystem services, including the provision of natural resources, regulation of atmosphere–land surface interactions, and support of social and cultural activities. Atmospheric deposition of reactive nitrogen (N deposition) represents an important nutrient input to forest ecosystems; however, most nitrogen-addition experiments fail to emulate the chronic, canopy-level inputs that occur under real-world conditions. Across the Alps, total nitrogen deposition has steadily declined since the late 1980s, but current annual deposition remains at medium to high levels (on average ~15 kg N ha⁻¹ yr⁻¹). Understanding how nitrogen deposition affects Alpine forests—particularly against a backdrop of declining inputs—is therefore critical for anticipating future forest functioning and ecosystem service provision. Meanwhile, most existing studies examine the effects of nitrogen deposition on a limited number of forest functions, implicitly assuming that, after accounting for (a)biotic drivers, residual variation in the focal functions is independent of other, unexamined forest functions. Given the complexity of forest ecosystems and the exchange of mass and energy across ecological processes, this assumption of independence of intrinsic interactions among forest functions is likely violated, potentially leading to biased inference. Here, we leverage long-term Swiss forest inventory data spanning broad environmental gradients and jointly model 13 forest functions within a multivariate framework that explicitly captures trade-offs and latent relationships among functions. We show that inference on the effects of nitrogen deposition differs substantially between univariate and multivariate models, including a sign flip of the inferred impact of nitrogen deposition on some key functions (such as bird diversity). Our results highlight the importance of viewing forests as emergent ecosystems and demonstrate that multivariate approaches provide a suitable basis for assessing global change effects. By integrating expert-based evaluations of the relative importance of individual forest functions to different ecosystem services, we further quantify the marginal impacts of historical nitrogen deposition on forest ecosystem services, offering insights directly relevant to forest management and policy.

Metacommunity theory has expanded our understanding of how spatial dynamics and local interactions influence species communities. Different assembly archetypes, reflecting different roles of species differences, habitat differences, and dispersal have been described, but we lack empirical studies specifically in terrestrial habitats testing which archetype is most important. In a replicated design, we experimentally enhanced structural between-patch heterogeneity in homogeneous production forests and developed a statistical framework controlling for sample incompleteness to detect different metacommunity processes. Meta-analyses on > 100 K individuals of > 1.3 K beetle species showed an increase of ~60 species in heterogenized forests at γ-level promoted by increasing α-diversity consistent with the mass-effect and an increase of β-diversity by ~10% supporting species-sorting. Additionally, we tested β-deviations from random assembly as a proxy of neutral processes. Findings indicate that enhancing structural heterogeneity can shift forests from patch-dynamics dominance towards mass-effect and species-sorting, offering a promising pathway to restore biodiversity in managed landscapes.

Tropical forests provide vital ecosystem functions and services, yet global change is intensifying disturbance regimes and expanding the extent of young secondary forests. The question is to what extent these young forests recover ecosystem multifunctionality and under which conditions recovery proceeds faster. Here, we analyze the drivers and mechanisms that shape a comprehensive set of 16 ecosystem functions related to carbon, water, and nutrient cycling. We established plots in 36 young secondary forest stands (2.3–3.6 years since agricultural abandonment) in dry and wet regions in Ghana. In each plot, we measured eight forest attributes related to structure, diversity, and functional composition, six soil physical and chemical properties, and quantified 16 ecosystem functions to test how environmental conditions and forest attributes shape ecosystem functioning using structural equation modeling. Climatic wetness and soil conditions most strongly influenced ecosystem functions (9 functions each), followed by structure (8), diversity (5), and functional composition (4). The relative importance of these drivers and mechanisms varied across cycles: The carbon cycle was most influenced by forest attributes, whereas the water and nutrient cycles were primarily shaped by environmental conditions, with forest structure additionally shaping nutrient cycling. Hence, in early successional ecosystems, ecosystem multifunctionality is more strongly shaped by environmental conditions and vegetation quantity than by biodiversity, and different conditions are needed for the recovery of different cycles. When previous land use intensity has been low, forest recovery can proceed fast, and natural regeneration offers a scalable, low-cost opportunity for restoring multifunctionality, especially in wet tropical forests.

Human activities are driving simultaneous native extinctions and alien naturalizations, reshaping global tree diversity with major implications for ecosystem structure and function. Here we analysed functional traits and environmental niches of 31,001 tree species worldwide, comparing naturalized, threatened and non-threatened species to assess current patterns and project future shifts under intensified extinction and naturalization. Future tree-rich ecosystems are projected to become increasingly dominated by fast-growing, high-resource-use species with acquisitive traits, while slow-growing, conservative species face greater extinction risk. Although group means along the main functional axes do not differ significantly, naturalized species occupy broader functional and environmental spaces and thrive in colder and more variable climates, whereas threatened species are more specialized to warm, stable and nutrient-rich environments, with non-threatened species intermediate. Projected naturalizations expand local functional diversity, but their acquisitive strategies could reduce long-term ecosystem stability, while extinctions cause pronounced contractions of functional and environmental trait space, especially in climatically variable regions. Overall, our findings reveal an accelerating global shift towards faster-growing tree communities, with likely consequences for carbon storage and biodiversity, underscoring the need to safeguard slow-growing species and limit the dominance of acquisitive trees.

The relationship between herbaceous above ground biomass and species richness typically exhibits a unimodal pattern, shifting from positive under low-precipitation conditions to negative under high-precipitation conditions. While shrub encroachment generally reduces both herbaceous aboveground biomass and diversity, how shrubs mediate the herbaceous biomass-richness relationship under altered precipitation regimes remains unclear. By synthesizing data from globally distributed precipitation manipulation experiments, we reveal contrasting herbaceous biomass-diversity responses in grasslands and shrublands. In grasslands, reduced precipitation shifts the peak of the unimodal herbaceous biomass-richness curve toward lower biomass, whereas increased precipitation shifts it toward greater biomass. In contrast, the peak of the unimodal relationship in shrub-dominated systems shows no significant shifts across precipitation extremes. These global patterns are supported by a 5-year field experiment in a desert steppe in Northern China, which further shows that precipitation change strongly affects species richness through soil water availability in grasslands, while exerting weaker effects through modifications of the fast-slow leaf economics spectrum in shrublands. These findings demonstrate that shrub encroachment can constrain precipitation-induced changes in herbaceous biomass-diversity relationships, providing important insights into how woody plant expansion interacts with climate change to influence ecosystem structure and function.

Carbon storage is a crucial ecosystem function supporting climate change mitigation, which varies across ecosystems and vegetation types. Despite recent studies showing that tree diversity can drive tree aboveground carbon stocks, we still have limited knowledge on the importance of different components of biodiversity for carbon storage in different vegetation types, especially within understudied ecosystems as the Brazilian Cerrado. In this study we aimed to understand (i) How does the relationship between taxonomic diversity and carbon storage differ among vegetation types in the Cerrado? (ii) What is the most influential factor driving aboveground carbon across Cerrado vegetation types: taxonomic diversity, functional diversity, phylogenetic diversity, or functional dominance? Using surveys of woody species from 167 plots in the Brazilian Cerrado, we calculated taxonomic, functional and phylogenetic diversity, and functional dominance of tree species, and assessed the relationship between these diversity components and aboveground carbon stock. The results showed that aboveground carbon stock increased significantly along the vegetational structural gradient, being highest in Woodland Savanna (33.3 ± 16.9 Mg/ha) and lowest in Typical Savanna (6.96 ± 5.28 Mg/ha). Diversity - aboveground carbon stock relationships differed across vegetation types. In Typical savanna, functional richness was positively related to aboveground carbon. In Woodland savanna, carbon stocks were negatively driven by functional dominance, carbon decreased with higher CWM wood density. Therefore, carbon storage in the Cerrado increases from open to forest-like vegetation, but the drivers varied: in open areas, species complementarity boosts carbon stocks, while in denser formations, carbon is mainly determined by the dominance of species with particular functional traits.

Abstract. Global forest assessments assist climate policy development, ecosystem science, and conservation planning, yet they rely on biomass and canopy data that do not explicitly represent the stand structural attributes derived from tree diameter measurements. This limits the ability to compare size-related structure and within-stand heterogeneity at large spatial scales. Here we present a global, spatially explicit dataset of stand-level tree diameter structure for forest cover in 2020 at 0.027° (~3 km) resolution, based on 1,203,524 georeferenced forest inventory plots comprising 54.6 million trees (≥10 cm DBH) integrated with more than 50 environmental and satellite-derived covariates into machine learning models. The dataset provides the first globally consistent maps of three complementary diameter-based metrics: arithmetic mean diameter (Dmean), quadratic mean diameter (Dqm), and the coefficient of variation of diameter (Dcv), representing average tree size, large-tree dominance, and within-stand size variability, respectively. Model performance of the ecozone-specific Random Forest framework ranged from R² = 0.41–0.82 (RMSE = 3.91–4.63 cm) for Dmean, R² = 0.43–0.83 (RMSE = 4.38–5.27 cm) for Dqm, and R² = 0.47–0.62 with (RMSE = 0.10–0.13) for Dcv across different forest ecozones. By jointly quantifying central tendency and variability in tree size, the dataset revealed spatial patterns of forest structural organization not captured by existing biomass or canopy-height products. It provides a consistent baseline for cross-biome comparison of forest structure, supporting parameterization and evaluation of vegetation and Earth system models, while offering an independent benchmark for remotely sensed structural proxies. Furthermore, it enables spatial assessment of stand structural attributes, including large-tree dominance and structural complexity, facilitating integration of diameter-based structure into global analyses of carbon dynamics and ecosystem functioning.

Nature-inclusive farming aims to balance agricultural productivity with environmental sustainability. Measures such as creating more semi-natural areas and reducing pesticide use, which are central to nature-inclusive farming, are expected to benefit arthropod biodiversity. However, it is unclear whether the expected increased abundance of natural enemies effectively enhances biological pest control and thus helps farmers achieve yields similar to conventional farming. This study examines the relationships between farming systems, pest and natural enemy abundance and how these affect potato yield quantity and quality. We sampled 20 potato fields in nature-inclusive and conventional farming systems, in Western Netherlands. In each field, we surveyed natural enemies, pests, and other arthropods, and quantified leaf damage both early and late in the growing season. Later in the season, potatoes were harvested, tuber damage was assessed and yield quantity and quality were determined. Our results showed that potato fields in the nature-inclusive farming supported higher arthropod abundance, including pests, natural enemies and other species. In the conventional farming, pests increased throughout the season, while natural enemies decreased over time and with distance from the field edge. In the nature-inclusive farming, pests also increased over time and decreased with distance from the field edge. Yield quantity and yield quality did not differ significantly between farming systems. These results indicate the possibility to boost within-field biodiversity and reduce agro-chemical input without compromising agricultural productivity per hectare with nature-inclusive farming systems. These approaches require agricultural land taken out of production, so overall less land is available for farming.

Humans are driving biodiversity change, which also alters community functional traits. However, how changes in the functional traits of the community alter ecosystem functions-especially belowground-remains an important gap in our understanding of the consequences of biodiversity change. We test hypotheses for how the root traits of the root economics space (composed of the collaboration and conservation gradients) are associated with proxies for ecosystem functioning across grassland and forest ecosystems in both observational and experimental datasets from 810 plant communities. First, we assessed whether community-weighted means of the root economics space traits adhered to the same trade-offs as species-level root traits. Then, we examined the relationships between community-weighted mean root traits and aboveground biomass production, root standing biomass, soil fauna biomass, soil microbial biomass, decomposition of standard and plot-specific material, ammonification, nitrification, phosphatase activity, and drought resistance. We found evidence for a community collaboration gradient but not for a community conservation gradient. Yet, links between community root traits and ecosystem functions were more common than we expected, especially for aboveground biomass, microbial biomass, and decomposition. These findings suggest that changes in species composition, which alter root trait means, will in turn affect critical ecosystem functions.

The Cerrado biome encompasses different vegetation types, ranging from savanna-like vegetation to forest-like vegetation, represented by a vegetational continuum from Cerrado Típico, Cerrado Denso and Cerradão, respectively. Nevertheless, there are still uncertainties on whether these different vegetation types do not only differ in their vegetation structure, but also in their species compositions. Based on vegetation surveys from 167 plots in the central Brazilian Cerrado, we addressed two questions: (i) How variable is the vegetation structure and species between different Cerrado vegetation types? Second, (ii) how strongly are vegetation structure and species composition linked? To answer these questions, we performed hierarchical clustering for species composition and vegetation structure. Our results showed that for species composition only 18

More than 40 thousand species of plants and animals are facing extinction worldwide. Range size is one of the strongest determinants of extinction risk, but the causes underlying the wide variation in natural range sizes remain poorly understood. Here, we investigate how species' age is related to present-day range size for over 26,000 species of mammals, birds, reptiles, amphibians, reef fishes, and plants. We show that, on average, older species have larger ranges across all groups except for marine mammals, but the strength of the age-range size relationship depends on taxonomic scale. Furthermore, while our results confirm the well-established pattern of smaller range sizes for species restricted to islands (compared to mainland) or with limited dispersal abilities (compared to good dispersers), we show that the correlation between species age and range size is stronger in these groups, suggesting that island dynamics and dispersal ability modulate this relationship. Our study reveals that species with small ranges, and thus increased extinction risk, tend to be restricted to islands, are poor dispersers, or have recently evolved.

Metacommunity theory has expanded our understanding of how spatial dynamics and local interactions influence species communities. Different assembly archetypes, reflecting different roles of species differences, habitat differences, and dispersal have been described, but we lack empirical studies specifically in terrestrial habitats testing which archetype is most important. In a replicated design we experimentally enhanced structural between-patch heterogeneity in homogeneous production forests and developed a statistical framework controlling for sample incompleteness to detect different metacommunity processes. Meta-analyses on >100K individuals of >1.3K beetle species showed an increase of ∼60 species in heterogenized forests at γ-level promoted by increasing α-diversity consistent with the mass-effect and an increase of β-diversity by ∼10% supporting species-sorting . Additionally, we tested β-deviations from random assembly as a proxy of neutral processes . Findings indicate that enhancing structural heterogeneity can shift forests from patch-dynamics dominance towards mass-effect and species-sorting , offering a promising pathway to restore biodiversity in managed landscapes. ### Competing Interest Statement The authors have declared no competing interest. Deutsche Forschungsgemeinschaft, https://ror.org/018mejw64, 459717468

The intensification of agriculture has been identified as one of the main causes of arthropod declines. To halt the decline of arthropods, changes in farming practices and management of surrounding habitats may therefore be needed. A key challenge is to identify which changes in management approaches are most effective in restoring biodiversity. Therefore, this study examines arthropod abundance and diversity in different agricultural and semi-natural habitats, and among different management types. Arthropods were sampled three times in spring and summer of 2022 and 2023 with emergence traps in 128 unique sites in an intensively farmed area in Western Netherlands. These sites included a variety of crops as well as semi-natural habitats. Our study showed that on average the abundance and diversity of arthropods of several taxa was lower in crop habitats compared to semi- natural habitats. However, these effects strongly varied among crop species. For instance, alfalfa, spelt, spring and winter wheat fields (that often had a high plant cover) supported similar arthropod diversity and abundance levels as semi-natural habitats. Interestingly, in crop fields most variables related to field management, such as herbicide applications or amount of nitrogen fertilizers, did not show any significant relationship with arthropod abundances or diversity. The number of days after cultivation was an exception, and was positively related to total arthropod abundance, Hymenoptera and Collembola abundances, and Coleoptera family diversity. Within semi-natural habitats, number of days after mowing was positively related to total arthropod abundance, Diptera, Hemiptera and Hymenoptera abundances, and Hemiptera family diversity. Additionally, plant cover was positively related to total arthropod abundance. Overall, our findings suggest that crop species and management practices that increase plant cover in spring and early summer are increasing arthropod abundance and, to a lesser extent, higher-taxa diversity in intensively farmed agricultural landscapes.

Sodium (Na) is an essential nutrient for animals, but not for most plants. Consequently, herbivores may confront a mismatch between forage availability and metabolic requirement. Recent work suggests that larger-bodied mammals may be particularly susceptible to Na deficits, yet it is unknown whether Na availability constrains the density or distribution of large herbivores at broad scales. Here we show that plant-Na availability varies >1,000-fold across sub-Saharan Africa and helps explain continent-scale patterns of large-herbivore abundance. We combined field data with machine-learning approaches to generate high-resolution maps of plant Na, which revealed multi-scale gradients arising from sea-salt deposition, hydrology, soil chemistry and plant traits. Faecal Na concentration was positively correlated with modelled dietary Na, supporting the prediction that variation in plant Na is a major determinant of herbivore Na intake. Incorporating plant-Na availability improved model predictions of large-herbivore population density, especially for megaherbivore species, which are depressed in very-low-Na regions (<100 mg kg-1), consistent with Na limitation. Our study offers an explanation for the scarcity of megaherbivores in parts of Central and West Africa, which has major ecological ramifications given the strong influence of large herbivores on ecosystem functioning and the profound human-induced changes to Na availability in Africa and beyond.

Although the interest in root traits has increased in recent years, we still have limited knowledge of (i) whether functionally different fine roots—absorptive versus transport roots—have similar trait coordination and (ii) how they help to explain plant performance, such as growth. We measured traits of 25 European broadleaved tree species growing in a research arboretum to study (i) the coordination of root traits within absorptive and transport fine roots and (ii) the degree of trait-tree growth relationships. To do so, we combined a suite of morphological and anatomical traits for each of the absorptive and transport roots. Despite remarkable differences in average trait values between absorptive and transport roots, our study shows that trait coordination within absorptive and transport roots is relatively similar. Our results also show that, for the selected traits, tree growth is better explained by absorptive root traits than by transport root traits and is higher in species with thinner roots. The stronger relationship between absorptive roots and tree growth highlights that roots mostly involved with resource absorption are more important in explaining tree growth than transport roots, which are mainly responsible for resource transportation.

Species' traits and environmental conditions determine the abundance of tree species across the globe. The extent to which traits of dominant and rare tree species differ remains untested across a broad environmental range, limiting our understanding of how species traits and the environment shape forest functional composition. We use a global dataset of tree composition of >22,000 forest plots and 11 traits of 1663 tree species to ask how locally dominant and rare species differ in their trait values, and how these differences are driven by climatic gradients in temperature and water availability in forest biomes across the globe. We find three consistent trait differences between locally dominant and rare species across all biomes; dominant species are taller, have softer wood and higher loading on the multivariate stem strategy axis (related to narrow tracheids and thick bark). The difference between traits of dominant and rare species is more strongly driven by temperature compared to water availability, as temperature might affect a larger number of traits. Therefore, climate change driven global temperature rise may have a strong effect on trait differences between dominant and rare tree species and may lead to changes in species abundances and therefore strong community reassembly.