Global Ecology and Biogeography

Land-use and climate change are dominant drivers of terrestrial biodiversity change, yet are usually analysed separately although they co-occur and may interact. We integrated global bird assemblage records from PREDICTS with temperature anomalies and species' ecological characteristics to test how land use modifies biodiversity responses to climate warming across three dimensions: local abundance and richness, compositional dissimilarity among assemblages, and species occurrence across ecological groups. Land use modified warming associations for both abundance and richness. Relative to primary vegetation, warming associations were more positive in low-intensity agriculture for both responses, but more negative for richness in high-intensity agriculture and urban land. Predicted richness remained below the reference, defined as primary vegetation at temperature anomaly 0, across all modified land uses, with the largest declines in high-intensity agriculture (-17.9%) and urban land (-21.8%). Within land-use classes, greater warming exposure was generally associated with higher compositional similarity, consistent with warming associated biotic homogenisation. Occurrence models revealed ecological filtering: broad-niched generalists were favoured in warmer modified habitats, whereas range-restricted habitat specialists were filtered out under intensive land use and warming. Conservation assessments should therefore integrate land-use-warming interactions with changes in assemblage composition and ecological strategies, particularly in agricultural and urban landscapes where warming further disadvantaged range-restricted specialists.

Forecasts of biodiversity responses to climate change often rely on space-for-time substitution, in which spatial biodiversity-climate relationships are used to predict biodiversity change through time. Yet this approach is rarely tested directly because long-term biodiversity time series are scarce. Here, we combine global modern and fossil assemblage data of planktonic foraminifera with site-specific sea-surface temperature reconstructions to compare biodiversity-temperature relationships across space and time. Spatial and temporal compositional turnover models showed similar slopes but consistently different intercepts, with spatial models predicting higher turnover across the full temperature gradient. Restricting the spatial comparison to the environmental domain of individual fossil time series reduced, but did not eliminate, this intercept mismatch. For alpha diversity, spatial models more closely recovered the temporal biodiversity-temperature relationship than for compositional turnover. Thus, for the timescales studied here, space-for-time substitution captures the direction of biodiversity change but not its magnitude through time.

Evidence is accumulating that global change is altering species distributions. Yet, detailed knowledge is missing about the relative and joint contribution of different drivers to observed species responses. Here, we implemented an impact attribution framework based on counterfactual simulations to assess the impact of climate and land use change on occupancy dynamics of North American breeding birds. We used a Bayesian framework to fit process-explicit dynamic occupancy models to long-term survey data for 159 species from 1995 to 2019, and quantified predictive performance using spatial and temporal cross-validation. We then assessed the relative importance and effect direction of climate and land use change while accounting for model predictive accuracy. Results indicate that climate change negatively affected 90 % of the species and land use change negatively impacted 96 %. Climate change emerged as more important than land use change for driving changes in occupancy across species. Remarkably, the effects of both drivers were mostly antagonistic rather than acting additively or synergistically. Climate was the most important driver for bird communities in the western USA, while land use change dominated in the southeast, and combined climate and land use change in the northeast. Our analysis demonstrates that recent changes in North American bird distributions are shaped by multiple global change drivers acting in concert. The effect of recent climate and land use change were mostly antagonistic, and thus trends in bird occupancy dynamics could not be understood by studying the impact of those drivers in isolation. By disentangling the effects of climate and land use change on biodiversity trends, impact attribution approaches can improve our understanding of global change impacts and can support conservation planning and more accurate and realistic projections of biodiversity response to global change.

Biodiversity loss is driven by unsustainable human activities, yet the contextual conditions and underlying drivers of threats remain poorly understood. We assessed how protected areas, socioeconomic conditions, and biophysical factors explain global patterns of threat probabilities across six major threat types and four vertebrate taxa. We identified key explanatory variables and their associations with threats using Extreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP). Socioeconomic conditions, specifically human development and income inequality, were the strongest predictors. Their associations were complex and non-linear: notably, high human development index (HDI) was associated with both higher and lower threat probabilities, depending on inequality and regional context. Second, land cover and biophysical variables, such as shrubland cover, tree cover, and elevation range, explained additional, but taxon-specific variation. Finally, protected areas showed limited ability to explain threat patterns. By linking threat probabilities to their contextual and socioecological conditions, we aim to build a better understanding of the systemic drivers of biodiversity loss.

Species are dramatically shifting their geographical ranges, yet the consequences of these spatial redistributions on species interactions have not been examined at broad spatial and temporal scales. Here, we investigate how the redistribution of species abundance over the past 50 years affects the potential for predator-prey interactions among North American birds. We first predict potential predator-prey interactions based on existing data and functional traits, then construct a novel, abundance-weighted metric of interaction potential for each pair of predator and prey in local communities. Across North America, the potential for predator-prey interactions has been increasing over time. We further show that this widespread increasing trend in interaction potentials is mostly driven by higher abundances of predator species. The spatial redistributions of predators and prey lead to turnover of interactions within local communities, and the turnover is less associated with changes in climate but more associated with human-induced land use changes. Our novel approach and results highlight the importance of considering traits, abundance, and species interactions - including known and potential interactions - when studying the ecological consequences of species range shifts.

Globalization is redistributing species worldwide, yet whether the traits and origins of non-native fauna have changed through time remains unclear. We combined global first-record data for non-native species from 1800-2019 with harmonized information on body size, diet, habitat use, native range characteristics, and climatic niche characteristics for 1,910 non-native mammals, birds, reptiles, amphibians, and freshwater fishes. Across most groups, species recorded earlier originated disproportionately from higher latitudes, occupied broader native ranges, and had wider thermal niches. More recent first records increasingly involve species from warmer, lower-latitude regions with smaller and more restricted native distributions. Body size also declined through time in several groups, whereas shifts in diet and habitat use were more taxon-specific. Temporal changes in introduction pathways partly explained these patterns: declines in deliberate release and production-related pathways, together with increases in pet and ornamental pathways, were associated with shifts toward smaller-bodied, lower-latitude, and more range-restricted species. These results indicate that the functional and biogeographic composition of non-native vertebrates has been progressively reshaped over the past two centuries, weakening the historical dominance of widespread temperate species and increasingly incorporating tropical and range-restricted fauna into global redistribution. Anticipating future biological invasions will therefore require attention not only to the number of species being transported, but also to how the characteristics and pathways of transported species are changing through time.

Climate influences community assembly by constraining the conditions under which species can persist, but the consistency of macroecological processes across different ecosystems remains unclear. Interspecific variation in climatic niche properties that govern community assembly across climate gradients can be gleaned from species distributions. Species-climate associations, niche properties, and resulting assembly remains poorly understood for plants in tropical dry ecosystems, and among different life-forms. We examined how species-climate associations governed community assembly of four plant life-forms across 60,000 km2 of tropical dry ecosystem in peninsular India. In the 1750 km long Eastern Ghats mountain range, we surveyed vegetation in 2500 20 x 50 m plots. Across the north-south climatic gradient from cool, wet and seasonal sites to warm, dry and less-seasonal sites, from presence-absence data of 1601 species in four life forms (trees, shrubs, herbs, climbers), we performed Bayesian Hierarchical Modelling of Species Communities to predict conditions of occurrence for each species. From this, we derived species climatic niche optima and niche width, and examined the local-level prevalence of niche properties across the climate gradient to glean assembly. Most tree, shrub and climber species associated with warm-dry conditions had wider niches than species associated with cool-wet conditions, which also resulted in assemblages having wider niches at warmer sites. Herbaceous species, by contrast, had narrower niches when associated with warmer conditions, where narrow-niche species dominated the assemblage. In all life-forms, however, assemblages in both warm-dry and cool-humid conditions consisted of species primarily associated with and preferring (having their optima in) those conditions, suggestive of stress dominance. Further evidence for stress dominance in shrubs and climbers came from assemblages in the warmest and coolest sites having low richness and comprising mainly of species with wider niches. Tree richness increased at either end of the gradient, while herb richness increased in warm-dry conditions. Overall, our results suggest that plant life-forms differ in the processes driving assembly across broad climate gradients in a tropical dry ecosystem, but many herbs were specialized to warm-dry climates. To understand life-form-specific responses to environmental gradients in tropical dry ecosystems, future work should incorporate traits and evolutionary history.

Beta diversity is a fundamental component of regional biodiversity that accumulates from compositional differences between local species assemblages. Although beta diversity is increasingly applied across spatial scales, its scale dependence remains incompletely synthesized, particularly concerning variation in spatial scale used to define alpha diversity (grain size). Using tree community data from Barro Colorado Island, we find that both additive and multiplicative beta diversity are consistently higher for unequal than equal grain divisions across different spatial extents and numbers of grains. These results can be explained by Jensen's inequality based on the concave-down relationship of alpha diversity with area that in turn increases beta diversity through the scaling relationship between alpha and gamma diversity. Combined with our additional analysis showing that this prediction is robust to more general models of species richness, including species--area and species--sampling-effort curves, these results reveal a previously unrecognized, predictable range of beta diversity variation.

In Switzerland, glaciers are projected to shrink to minimal size by the end of the century. Thus, climate change puts pressure on glacial specialist plant species, as generalist plant species colonise their habitat. As bare areas are revealed by glacier retreat, glacial specialists can likewise shift their distributions to higher altitude, however, there will be no habitat for them to colonise. Thus, Swiss mountain floral biodiversity and ecosystem services will likely be locally extirpated. In this article, we use Species Distribution Models of 369 plants occurring in Swiss proglacial areas fitted using bioclimatic, lithological and topographic variables and compare the covariates that most strongly predict the distributions of glacial specialist and generalist species. In addition, we use two methods of defining glacial specialist species and separating them from specialists: empirical (degree of prevalence of species in proglacial areas) and ecological (using Landolt values). We find that both approaches yield similar results: the distributions of both generalist and glacial specialist species are most strongly predicted by bioclimatic variables, however, they are significantly stronger for glacial specialists. On the other hand, distributions of generalist species are more strongly predicted by topographical and lithological variables.

Biodiversity aggregators such as GBIF provide unprecedented access to global biodiversity data, yet their representativeness remains uneven across space and taxa. This study examined the spatial and taxonomic structure of global vascular plant data available on GBIF. Six filters were applied to the GBIF vascular plant dataset, resulting in the removal of 54% of all records. Together, the filters explained more than 90% of the identified spatial issues, with duplicate and missing coordinates accounting for most of the variation. A higher number of occurrence records was associated with a greater number of spatial issues. Record distributions became progressively more even at finer taxonomic levels, from orders to species. The time series of occurrences for species, genera, and families increased sharply after 1800 and continued to rise, with no apparent stabilisation. Of the 824 ecoregions covered, 73 accounted for 72% of all occurrence records. These ecoregions spanned all continents but were strongly concentrated in Europe, followed by North America and Oceania. The analyses reveal four key patterns: (1) data volume is positively associated with spatial issues; (2) a small number of taxa account for a large proportion of records, whereas many are represented by relatively few; (3) occurrence data aggregated by GBIF have increased continuously since 1800; and (4) record coverage remains highly uneven across the world's ecoregions. These results highlight the substantial contribution of biodiversity data aggregators to expanding access to biological information while demonstrating the persistent spatial and taxonomic biases that shape their contents. Such biases should be explicitly considered when assessing data completeness and quality and when using aggregated occurrence records to infer global biodiversity patterns.

Understanding spatial and temporal variation in community composition is central to protecting and monitoring biodiversity. Similarity in the composition of two communities decreases along spatial and temporal gradients, a relationship known as distance decay. Comparing distance-decay relationships across taxonomic, functional, and bioclimatic facets of diversity provides a means of interrogating niche-based versus neutral influences on community assembly. Furthermore, the context in which these facets yield overlapping or complementary information about global change impacts remains poorly understood. In this study, we examined spatiotemporal distance-decay relationships for taxonomic, functional, and bioclimatic facets of alpine plant diversity leveraging elevation gradients on five peaks in the White Mountains, California, USA, sampled at 3-4 time points between 2007 and 2024. Using multivariate Bayesian beta regression models, we estimated the slopes of elevation distance decay over multiple surveys and across taxonomic, functional and bioclimatic diversity to understand how spatial distance-decay relationships are changing through time and across different facets of diversity. We found strong spatial distance decay of taxonomic similarity across all peaks, with the highest elevation peak showing the strongest decay. Functional and bioclimatic similarities decayed more weakly than taxonomic similarity, suggesting environmental filtering shapes trait and niche distributions. Critically, spatial decay patterns showed no temporal signal across facets of diversity, indicating community stasis rather than biotic homogenization or differentiation. This study adds further evidence that xeric alpine plant communities are resisting climate change impacts through time.

Island biogeography is the theoretical and empirically validated expectation that an islands biodiversity is ultimately limited by its size and isolation, with larger and less isolated (from mainland communities) islands supporting greater diversity. Island biogeography is generally applied to simple metrics of diversity such as species richness (number of different species); however, fewer studies have used traits to measure biodiversity. An organisms traits -- e.g., body mass, age at sexual maturity, trophic level -- can be used to measure biodiversity and understand how ecological communities function. We quantified species richness for birds, mammals, reptiles, and amphibians, and functional diversity for birds and mammals (for which sufficient trait data were available), and tested whether this diversity can be predicted using the theory of island biogeography. We identified 9,103 Australian islands, of which 1,661 had at least one (native and/or non-native) non-marine species present according to the Atlas of Living Australia. As expected, tetrapod species richness (S) increased with island area (A) (z = 0.299 {+/-} 0.012) following a typical power-law relationship (i.e., S = cAz, where z = 0.2-0.4), but was not predicted by distance from mainland -- consistent with the pattern observed on other recently (< 10,000 years) isolated continental islands. We found that trait richness increased at the same rate with island area as species richness for mammals, but for birds, trait richness increased more slowly than species richness. Trait turnover increased modestly with inter-island distance, whereas trait nestedness was unrelated to distance. Trait richness increased strongly with species richness in both birds and mammals, and island area and isolation explained no additional variation in functional richness after accounting for species richness. These results indicate that island geography influences functional diversity primarily through species accumulation, rather than through direct effects on occupied trait space. Overall, the trait space of smaller islands tended to be nested within that of larger, nearby islands; the main differences among similar-sized islands are due to turnover (change in species/trait combinations among assemblages), and the effects are more pronounced in mammals compared to birds. We also found evidence for an asymptotic relationship between trait and species turnover in both birds and mammals, suggesting close coupling between taxonomic and functional turnover, with some saturation of trait turnover at high species turnover. Large islands that are simultaneously more isolated might offer conservation advantages by reducing the influence of threatening processes on the mainland if distance limits access of people and invasive species.

Plant phenology influences biotic interactions and the cycling of water, carbon, and nutrients, ultimately affecting global climate. Accurately quantifying phenological dynamics is therefore essential for ecological forecasting, yet estimates vary widely depending on data sources, smoothing approaches, and date-extraction techniques. For this reason, the selection of an appropriate processing pipeline requires benchmarking under controlled conditions. In this study, we use a Land Surface Model (LSM) to simulate ecosystem dynamics at four temperate forest sites under five lesser studied climate perturbations. The resulting synthetic dataset allows us to control for environmental conditions while comparing commonly used phenological detection methods (relative thresholds at 10%, 20% and 50%, highest rate of change, detection of inflection points in the curvature angle, detection of recovery and senescence points). Amongst tested methods, we find general agreement in responses to climate alterations, where inflection and low thresholds (10%) methods provide the closest match to the model predicted start of season, with a maximum discrepancy of 4 days. Higher thresholds (20%, 50%) are closer to the model predicted end of season, though discrepancies reach up to 10 days. High thresholds and rate-of-change methods also reliably detect the peak of season. We further show that some methods detect phenological responses missed by temperature-only type growing season, supporting the need for more realistic phenological representations in LSMs. Beyond evaluating extraction methods within a common framework, our study expands on the potential of using LSMs as sandboxes for ecological testing rather than solely predictive tools.

Identifying how species interact in ecological networks is key to understanding species' contributions to ecosystem functioning, but can be difficult to establish in species-rich communities. Functional niches, which capture broader ecological strategies, are often easier to assess and could help approximate species' interaction roles. We tested this by integrating species interaction and leaf functional trait data of tree species and leaf-associated interaction types from a large-scale forest biodiversity experiment. We found that identity, variability, and similarities of functional niches shaped corresponding aspects of interaction roles. Interestingly, however, this association inversed in the case of functional niche variability, which decreased instead of increased the variability of species interactions. This suggests a potential trade-off between processes that determine variability in functional and interaction space. Furthermore, effects were not constrained within aspects, with similarities of interactions being particularly responsive to most tested niche aspects, indicating that interaction-based competition among plants is particularly sensitive to functional niche differences. Moreover, many effects of functional niches depended on tree species biomass and tree species richness, highlighting the importance of the larger ecological context for determining species interaction roles. Together, our findings show that species' interaction roles, while clearly altered by, are not simply a consequence of functional niches. Instead, interaction roles integrate multiple aspects of functional niches depending on species performances and community composition and can therefore be crucial for anticipating ecosystem change.

AimHere we aim to disentangle species-specific bioclimatic drivers of forest site productivity and project their future dynamics, providing a spatially explicit basis for anticipating climate-driven shifts in productivity and their implications for forest carbon sequestration. LocationIberian Peninsula. Time period1985-2014 (calibration); 2071-2100 (projected under CMIP6 scenarios). Major taxa studied21 Iberian tree species. MethodsWe used Site Form (SF) maps derived from the Third Spanish National Forest Inventory, spatially interpolating plot-level SF estimates as a continuous productivity index and relating them to 25 bioclimatic variables. Multiple linear regression models were selected via complementary stepwise and subset regression and validated on independent hold-out data (80%/20% split). ResultsValidated [Formula] ranged from 0.46 (Quercus faginea) to 0.97 (Pinus pinaster); 17 of 21 species reached [Formula]. BI013 precipitation of the wettest month), not BI014, was the most frequently retained predictor (15/17); BI014 was retained in only (11/17 models with a near-even sign split. Combining projected changes in mean productivity and habitat extent under SSP5-8.5, fifteen of sixteen applicable species lose total productivity by 2071-2100, six -- including Fagus sylvatica and Betula alba -- collapsing to below 1% of their reference-period value; only Pinus pinaster gains, and only under the lowest-emission pathway (up to 175%) -- under SSP5-8.5 it too loses productivity, albeit less than any other species (35% of its reference-period value retained). Limiting warming to SSP1-2.6 spares Mediterranean pine and oak species but not Euro-Siberian and montane ones. Main conclusionsThese validated, extrapolation-aware models reveal a near-universal, climate-driven collapse in Iberian forest site productivity, with direct implications for the carbon-sink potential currently attributed to these forest types, and provide a route to dynamic, climate-aware carbon-uptake estimates for the region.

Land-use change, such as the transformation of woody ecosystems into open pastures, acts as a strong ecological filter, favouring some species while excluding others according to differences in ecological niche breadth. Understanding how differences in niche breadth influence species responses under anthropogenic filters is crucial to anticipate their persistence or displacement. In this study, we quantified realized niche breadth in two sympatric ecosystem engineers, the Neotropical leaf-cutter ants Atta cephalotes and Atta laevigata, to test whether breadth differences are consistent with specialist and generalist ecological strategies. We characterized realized niche breadth across fine-scale environmental gradients by integrating hemispherical photography, microclimatic data, mound architecture, and edaphic profiles from 114 colonies across a regional transect in the Colombian Andes, alongside macroclimatic data from Copernicus. Principal Component Analysis (PCA) and PERMANOVA identified canopy openness and bushes- and tree-type vegetation density as the principal axes of interspecific niche partitioning. The observed differences in realized niche breadth were consistent with specialist and generalist ecological strategies. A. laevigata was predominantly associated with open-canopy areas, warmer micro- and macroclimatic conditions, and narrower edaphic dispersion. In contrast, A. cephalotes occupied a wider range of microhabitat conditions. This broader realized niche breadth is compatible with previous reports of A. cephalotes occurring in urban areas. Together, these findings suggest that niche breadth may influence how Neotropical leaf-cutter ants respond to habitat transformation, helping to understand the ecological consequences of land-use change.

Aim: Given that much of Earth's biodiversity is contained within species, inferring intraspecific genetic diversity and identifying its ecological correlates is essential for understanding evolutionary processes and informing conservation. Here, we investigate broad-scale variation in species-level mitochondrial genetic diversity and evaluate the relative importance of alternative ecological hypotheses proposed to explain it. Location: Brazilian Atlantic Forest, Iberian Peninsula, northwestern Africa, Arabian Peninsula, Madagascar and Australian Monsoonal Tropics. Taxon: Amphibians and reptiles Methods: We assembled a comprehensive dataset by integrating and manually curating mitochondrial sequences, occurrence records, environmental data and species traits from multiple open-access sources. We used multiple mitochondrial genes to estimate mean nucleotide diversity for each study species and quantified regional variation in genetic diversity. We then used random forests models to evaluate the relative importance of selected variables representing hypotheses related to water-energy availability, topography, historical climatic stability, land-cover characteristics, species geographic characteristics, life-history traits, evolutionary history and conservation status. Results: The final dataset comprised 247 amphibians and 295 reptiles, for which 43 and 52 explanatory variables were evaluated, respectively. Overall, the strongest support was found for hypotheses related to life-history traits, topographic heterogeneity and water-energy availability. In amphibians, higher genetic diversity was associated with smaller body size and greater environmental heterogeneity, particularly broader elevational and precipitation gradients. In reptiles, genetic diversity was primarily associated with life-history traits, with species of smaller body size and lower reproductive output exhibiting higher diversity. Long-term climatic stability showed comparatively little explanatory power for both taxa. Main conclusions: Our comprehensive study demonstrates that integrating extensive manual data curation with comparative macrogenetic analyses provides a robust framework for identifying broad-scale ecological correlates of mitochondrial genetic diversity. These findings improve our understanding of the factors associated with contemporary patterns of genetic diversity and provide a foundation for future conservation assessments in data-limited systems.

Biological invasions are a major driver of global change, reshaping ecosystems and threatening biodiversity worldwide. Anticipating where invaders will establish and where they will exert the strongest ecological impacts are key challenges for early detection and targeted management. Although Species Distribution Models (SDMs) are widely used to forecast biological invasions, they often provide uncertain estimates of establishment ranges and limited insight into invader performance, making it difficult to anticipate ecological impacts. Here, we address these limitations by integrating physiological information on invader performance with SDMs to identify regions of high invasion risk. Using the brown alga Rugulopteryx okamurae, one of the most prominent marine invaders in Europe, we first test alternative hypotheses of northern establishment limits: (i) a cold-survival constraint driven by winter temperatures and (ii) a growth constraint derived from the species' thermal performance. To identify the more likely scenario, we combine cold-tolerance experiments with seasonal growth comparisons between the invader and a native macroalga Dictyota dichotoma, whose established distribution allows physiological performance to be directly related to realised presence. Finally, we project seasonal growth of the invader across the predicted establishment range as a proxy for biomass accumulation and potential ecological impacts. Our results indicate that northern limit in Europe will be more likely constrained by winter survival rather than growth, extending the potential establishment range of Rugulopteryx to mid-Norway. In contrast, the highest impacts are likely to remain concentrated in southern Europe, where thermal conditions sustain high year-round growth. Overall, our approach illustrates how understanding the physiological response of invaders to their environment can improve the interpretation of SDM outputs and help identify areas at greatest risk of impact within their potential establishment range.

Target 12 of the Global Biodiversity Framework urges governments to enhance human access to nature to improve human wellbeing. Here, we study nature access using several metrics for a globally representative sample of 140 large Functional Urban Areas, examining variation among regions and over time. We find most urbanites globally do not reach common benchmarks for urban forest cover and nature access. Globally, 3.3 billion people (76% of urbanites) live in urban areas that do not have at least 30% tree canopy cover. Moreover, 1.1 billion people (23% of urbanites) are farther than 1 km from a park as identified in Open Street Map, and 1.5 billion people (36% of all urbanites) are more than 1 km from a green patch as defined by land cover. Over time, urban nature access has declined. Between 1992 and 2020, most urban residents had an increase in the distance to green patches (63% of urbanites increased, average increase 680 m). Similarly, between 1992 and 2020, 31% of urbanites had a decrease in percent natural cover, while only 1.3% had an increase. We show that the variation among cities or regions in the amount of nature access depends on the metric used and the context. On average, mesic climates have more tree cover than do arid climates, and cities with lower GDP or higher population density tend to have lower natural share than other cities. Our results suggest that global urban nature access is insufficient for supporting human health and worsening over time.

Ecosystem engineers hold potential to modify the environment and resource availability. The recovery of the Eurasian beaver reintroduces both a novel trophic component, as herbivore and prey, and an ecological driver that alters landscape of resources and risks. Together, the species comeback may trigger cascading effects on the ecosystem and shape relationships among megafauna, with contrasting effects on different trophic groups. We studied 30 beaver sites and paired reference sites in forests across Poland to assess how beaver presence affects habitat use and interactions among ungulates, large carnivores and mesocarnivores. With the same species composition and species richness, the number of detections of animals was lower at beaver sites, whereas detection duration was longer there. Structural equation modelling showed that beaver affects mammal community via a combination of direct and indirect pathways. The species presence had a positive direct effect on large carnivores, partly offsetting the negative indirect pathway mediated through reduced ungulate presence. These effects extended indirectly further to mesocarnivores, detection of which was positively related with increasing number of detections of ungulates and large carnivores. Beaver effects on habitat were spatially structured: canopy openness and deadwood abundance declined with increasing distance to water. Ungulates showed spatially diversified response at beaver sites, with the number of detections increasing away from the water, whereas large carnivores were detected most frequently near the water. Ungulates also changed seasonally their behaviour along water-land gradient, indicating a trade-off between resource acquisition and perceived predation risk. Our results show that beaver engineering reorganizes ecosystem through spatial and temporal changes in habitat use, behaviour and trophic interactions among large and medium-sized mammals. Beaver recovery may therefore restore ecological complexity by generating fine-scale mosaics of resources and risk that propagate across multiple trophic levels.