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ABSTRACT Aim This paper presents a probabilistic method for the characterization of pollen taxa using attributes, and for the reconstitution of past biomes. The probabilities are calculated on the basis of European floristic and pollen databases sufficiently large and exhaustive to provide robust estimates. Location The analysis is based on data from approximately 1000 sites throughout Europe. Method We use all the pollen data from the European Pollen Database (EPD), which contains about 50 000 pollen assemblages distributed across Europe and covering the period from the Last Glacial Maximum to the present. Using existing floras, each pollen taxon has been characterized by allocating one or more modes of several attributes, chosen according to the biogeography and phenology of the taxon. With this information, conditional probabilities are defined, representing the chance of a given attribute mode occurring in a given pollen spectrum, when the taxa assemblage is known. The concept of co-occurrence is used to provide a greater amount of information to compensate for difficulties in the identification of pollen grains, allowing a better interpretation when there is little diversity in the pollen assemblage. Results The method has been validated using a dataset of modern samples against existing methods of biome classification and remote sensing data. An application is proposed in which the new method is used to produce biomes for pollen data 6000 years ago. This confirms previous results showing an extension of the deciduous forest to the north, east and south, explained by milder winters in western and northern Europe, and cooler and wetter climate in the Mediterranean region. Conclusion The results show the new method to be efficient, reliable and flexible and to be an improvement over the previous method of biomization. They will be used to test simulations of earth system models running on periods with climate significantly different from the present day,... [ABSTRACT FROM AUTHOR]

Aim One of the main gaps in the assessment of biodiversity is the lack of a unified framework for measuring its taxonomic and functional facets and for unveiling the underlying patterns. Location Europe, 25 large river basins. Methods Here, we develop a decomposition of functional β-diversity, i.e. the dissimilarity in functional composition between communities, into a functional turnover and a functional nestedness-resultant component. Results We found that functional β-diversity was lower than taxonomic β-diversity. This difference was driven by a lower functional turnover compared with taxonomic turnover while the nestedness-resultant component was similar for taxonomic and functional β-diversity. Main conclusions Fish faunas with different species tend to share the same functional attributes. The framework presented in this paper will help to analyse biogeographical patterns as well as to measure the impact of human activities on the functional facets of biodiversity. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim This paper describes a set of integrative scenarios developed in the ALARM (Assessing LArge-scale environmental Risks for biodiversity with tested Methods) project. The ultimate aim of ALARM was to develop and test methods and protocols for the assessment of large-scale environmental risks to biodiversity and to evaluate mitigation options. Scenarios provide a tool for exploring such risks and the policy options to mitigate them; therefore they play a central role within the ALARM project. Methods Three integrative scenarios (liberalization, business as might be usual, sustainability) were developed and illustrated using the econometric model described in a subsequent paper. They are contextualized with projections from climate models and provide the input for model-based assessments of biodiversity trends. Additionally, three shock scenarios were developed (Gulf Stream collapse, peak oil, pandemic) to demonstrate the limits of linear extrapolation. As these extend beyond model capabilities, they are discussed semi-quantitatively based on modelling insights. Results Although the policy impacts on biodiversity are different for different pressures, biomes and species groups, some general trends could be identified. An extension of current EU policies will act as a brake on current trends by slowing down the loss of biodiversity in many cases and in most biomes, but it will be capable of neither halting nor of reversing the loss. Liberalization has the effect of accelerating biodiversity loss across the board, with few exceptions. A coherent sustainability scenario is clearly the most effective at preserving biodiversity, but the variant tested here still does not halt losses in all cases. Main conclusions Current EU policies for protecting biodiversity appear to be insufficient to reverse ongoing losses. Coherent sustainability strategies are effective at conserving biodiversity, but in order to assess losses and then reverse them, measures would need to be introduced that extend beyond the steps tested in the ALARM sustainability scenario. [ABSTRACT FROM AUTHOR]

This paper presents a probabilistic method of pollen spectra analysis. The method relies on a pollen taxon characterization using biotic and abiotic plant attribute modes, and their occurrence in a given pollen spectrum at a specific site. This type of analysis can provide an interpretation, which can lead to the reconstruction of the biome and, to an extent, of the abiotic conditions at the site.The analysis has been carried out at the European scale using data provided by the European Pollen Database for about 1000 sites. This dataset contains about 50,000 pollen spectra from the last 21 ka. In these spectra, each pollen taxon has been characterized by a set of 10 chosen attributes. These have been selected with regard to their relevance in biome reconstruction, but also on the basis of available literature. By using the probability of occurrence of each taxon in a given pollen spectrum, it is possible to calculate an affinity index for the spectrum to the attribute considered. To overcome difficulties caused by pollen identification in low diversified pollen spectra, a co-occurrence concept has been used to give more information.The method has been validated on a set of 1327 modern surface samples by comparing the results to the major climatic and environmental variables that control the distribution of the vegetation. A reconstruction exercise on various characteristics of the plants was then carried out on a 6-ka dataset. This confirmed previous studies by showing a strong dominance of deciduous forest over most of Europe, related to a milder climate than at present in the north and a wetter and colder climate than at present in the south. By analysing the change in pollen/seed dispersion strategies and the light requirement, we show that the history of vegetation dynamics in relation to human influences can be assessed using this method.Our results show that the probabilistic method is an objective tool for pollen assemblage analysis. It allows reconstruction of various characteristics of the vegetation at the continental and global scale for periods and sites with significantly different climate conditions. This method can also be used to compare maps of vegetation attributes for the validation of the new generalized dynamic ecosystems models. [ABSTRACT FROM AUTHOR]

Abstract The objective of the European Terrestrial Ecosystem Modelling Activity (ETEMA) was to address some of the major challenges in developing generalized models to examine responses of natural and seminatural ecosystems to environmental change at the regional to European scale. The approach described herein was to break down the totality of ecosystem functioning into its key components, each with its characteristic spatial and temporal scales. A conceptual framework was developed describing the configuration of these components as modules within a generalized simulation model. The framework describes the key inputs, outputs and state variables, their spatial and temporal contexts, and information flows between modules. The ‘backbone’ of the model is a system of nested timing loops corresponding to the disparate time scales at which different ecosystem processes occur. The framework is a theoretical construct into which ecosystem models at levels of complexity ranging from the very general to the highly detailed can be mapped, and thus provides a guide for development of models for novel, particularly regional-scale, applications. A number of subsystem studies of the major components of ecosystem functioning, i.e. modules of the conceptual framework, are briefly introduced herein. The general aim of the subsystem studies was to identify the key alternative formulations (as opposed to minor variants) and test these against observational data. The various subsystem studies concern planetary boundary layer–ecosystem interactions, ecosystem CO2 and H2O fluxes, vegetation physiology and phenology, biogeography and vegetation dynamics, detritus and SOM dynamics, soil moisture and human and natural disturbances and, as individual papers, they complete this special ETEMA issue. [ABSTRACT FROM AUTHOR]

Aim: Climate change regulates autumn leaf senescence date (LSD), exhibiting a strong phenological control of plant carbon uptake. Unlike the delaying effect of daily mean temperature (Tmean) on LSD, the impact of warming asymmetry in daytime and nighttime, as evidenced by variations of the diurnal temperature range (DTR), remains elusive. The objectives of this study were to investigate physiological and ecological impacts of DTR on LSD using long‐term in situ observations and to predict the future trends of LSD under warming. Location: Europe. Time period: 1950–2015. Major taxa studied: Plant phenology. Methods: We used partial correlation analysis, multiple linear regression and ridge regression to explore the impacts of DTR on LSD. To quantify the importance of potential drivers of LSD, we trained random forest models and applied the SHapley Additive exPlanations method to isolate the marginal contributions of each predictor on LSD. For LSD modelling and projection, we first evaluated two temperature‐driven LSD models [i.e., cooling‐degree‐day (CDD, without DTR effect) and day–night‐temperature CDD (DNCDD, with DTR effect)], then applied them to predict future LSDs. Results: We found that observational increases in Tmean and DTR had contrasting effects on LSD. Increased Tmean delayed the LSD, whereas larger DTR overall had an advancing effect. Considering the DTR effect, the Tmean sensitivity of LSD was 14% lower than presently estimated (2.4 vs. 2.8 days °C−1). Warming asymmetry‐related drought stress and plant functional traits (i.e., plant isohydricity and water‐use efficiency) potentially explained the advancing effect of DTR on LSD. We found that current projections of future LSD are overestimated because the DTR effect is discounted, suggesting the need for an adequate understanding of how plant phenology responds to warming asymmetry. Main conclusions: Our findings highlight the importance of DTR in controlling LSD variations with an advancing‐dominant effect and call for the improvement of phenology modelling incorporating the DTR effect. Given that DTR showed a globally narrowing trend over the last several decades, more efforts are needed to understand the potential ecological impacts of warming asymmetry and vegetation response to climate change. [ABSTRACT FROM AUTHOR]

Aim: The amount of forest edges is increasing globally due to forest fragmentation and land‐use changes. However, edge effects on the soil seed bank of temperate forests are still poorly understood. Here, we assessed edge effects at contrasting spatial scales across Europe and quantified the extent to which edges can preserve the seeds of forest specialist plants. Location: Temperate European deciduous forests along a 2,300‐km latitudinal gradient. Time period: 2018–2021. Major taxa studied: Vascular plants. Methods: Through a greenhouse germination experiment, we studied how edge effects alter the density, diversity, composition and functionality of forest soil seed banks in 90 plots along different latitudes, elevations and forest management types. We also assessed which environmental conditions drive the seed bank responses at the forest edge versus interior and looked at the relationship between the seed bank and the herb layer species richness. Results: Overall, 10,108 seedlings of 250 species emerged from the soil seed bank. Seed density and species richness of generalists (species not only associated with forests) were higher at edges compared to interiors, with a negative influence of C : N ratio and litter quality. Conversely, forest specialist species richness did not decline from the interior to the edge. Also, edges were compositionally, but not functionally, different from interiors. The correlation between the seed bank and the herb layer species richness was positive and affected by microclimate. Main conclusions Our results underpin how edge effects shape species diversity and composition of soil seed banks in ancient forests, especially increasing the proportion of generalist species and thus potentially favouring a shift in community composition. However, the presence of many forest specialists suggests that soil seed banks still play a key role in understorey species persistence and could support the resilience of our fragmented forests. [ABSTRACT FROM AUTHOR]

Aim: The aims of this study were to evaluate the changes in the length of the time period between leaf‐out and flowering across temperate tree species, and associate these changes with potential physiological and environmental drivers to enhance mechanistic insight into these phenomena. Location: Central Europe. Time period: 1980–2016. Major taxa studied: Six temperate woody species. Methods: Statistical analyses were carried out based on long‐term ground observations of both spring leaf‐out and flowering across temperate tree species during 1980–2016, a period characterized by rapid warming. Results: The temperature sensitivity of flowering (−5.4 ± 0.04 days/℃, mean ± SE) was higher than that of leaf‐out (−4.6 ± 0.04 days/℃) across all species, regardless of whether leaf‐out occurred before or after flowering. This study postulates a hypothesis attributing the different temperature sensitivities to different thermal sensitivities, thermal requirements, and photoperiodic controls. Main conclusions: The larger temperature sensitivity of flowering than leaf‐out resulted in an extended time period between flowering and leaf‐out in species that bloom before leafing out, but a shorter time period between these phenophases in species with the opposite strategy. We would like to emphasize the importance of changes in time period between different phenophases, and we recommend conducting experimental research to reveal the underlying mechanisms of plant phenology response to climate change, and to explore its potential ecological implications. [ABSTRACT FROM AUTHOR]

Aim: We assessed the spatial distribution of four different types of avian specialization throughout Europe, identifying landscape features associated with specialization and quantifying where the Natura 2000 network intersects with areas of high avian specialization. Location: Europe. Time period: Present day. Taxa studied: European breeding birds. Methods: We used the European Atlas of breeding birds and four avian specialization measures (diet, foraging behaviour, foraging substrate and habitat). We calculated specialization richness and identified geographical hotspots for each of these ecological traits. We tested whether elevational gradient, landscape heterogeneity or dominant land use predicted each type of specialization richness. We determined which types of European protected areas are most associated with higher specialization richness. Results: Diet and foraging substrate specialists increased with elevation, whereas richness of foraging behavioural specialists decreased. There was a greater richness of dietary and habitat specialists in forests than in other environments. The Natura 2000 areas declared under Bird and both directives (Birds and Habitats) intersected with a high dietary, foraging substrate and habitat specialist richness. The richness of foraging behaviour specialists was high in Birds directive areas. Single and multiple hotspots of specialization were greater in protected than non‐protected areas. However, almost 30% of specialization hotspots did not intersect with protected areas. Main conclusions: Our findings suggest that higher levels of avian specialization in Europe are positively associated with elevation and forested land cover. Importantly, we found that the Natura 2000 network supports all types of avian ecological specialization, albeit mainly in areas declared under both directives. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Human activities have weakened biogeographical barriers to dispersal, increasing the rate of introduction of alien plants. However, their impact on beta diversity and floristic homogenization is poorly understood. Our goal is to compare the phylogenetic beta diversity of native species with that of two groups of alien species, archaeophytes and neophytes (introduced before and after ad 1500, respectively), across European urban floras to explore how biological invasions affect phylogenetic turnover at a continental scale. Location Twenty European cities located in six countries between 49 and 53° N latitude in continental Europe and the British Isles. Methods To compare the phylogenetic beta diversity of native and alien species we use the average phylogenetic dissimilarity of individual floras from their group centroid in multivariate space. Differences in phylogenetic beta diversity among different species groups are then assessed using a randomization test for homogeneity of multivariate dispersions. Results Across European urban floras, and when contrasted with natives, archaeophytes are usually associated with lower levels of phylogenetic beta diversity while neophytes tend to increase phylogenetic differentiation. Main conclusions While archaeophytes tend to promote limited homogenization in phylogenetic beta diversity, because of their diverse geographical origin together with short residence times in the invaded regions, neophytes are not promoting biotic homogenization of urban floras across Europe. Therefore, in spite of the increasing rate of alien invasion, an intense phylogenetic homogenization of urban cities is not to be expected soon. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim This paper identifies socio-economic driving forces of biodiversity change and analyses their political and economic dynamics by modelling socio-economic parts of three scenario storylines developed for the ALARM (assessing large-scale risks for biodiversity with tested methods) project. In the BAMBU (business-as-might-be-usual) scenario policy decisions already made in the European Union (EU) are implemented and enforced, but no additional measures are introduced. The GRAS (growth applied strategy) scenario describes a future world orientated towards economic growth and complete deregulation. And finally, SEDG (sustainable European development goal) is a normative scenario focusing on the achievement of sustainable development. Methods The GINFORS (global inter-industry forecasting system) model is applied to quantify the effects of different sets of policy measures representing the three scenarios. It allows investigation of the inter-relations between socio-economic driving forces and the state of the environment. Results The presented results for the 25 EU countries focus on the following variables: unemployment, material extraction, energy supply and CO2 emissions. The lowest amount of unemployment is in the SEDG scenario, where it steadily decreases from 2005 to 2020. In BAMBU it falls to a level that is also below that of 2005. In GRAS, the number of unemployed people in 2020 is clearly over the value of 2005. The development of total material extraction from 2005 to 2020 is nearly stable in BAMBU, while it clearly increases in GRAS. Only in SEDG is there a reduction in resource use. None of the scenarios achieves a substantial reduction in energy use. However, the development of CO2 emissions shows a decoupling from energy supply. For BAMBU there is a slight decline in CO2 emissions over time, for GRAS they increase but with a slightly smaller growth rate than energy supply. In SEDG the emissions are reduced. The decoupling trends can be explained by a shift to more renewable energy sources in all scenarios, with the highest share in SEDG. Main conclusions The results indicate that a growth-oriented policy design, such as presented in the GRAS scenario, is not compatible with the conservation of biodiversity. Only in the SEDG scenario do the policy measures support the idea of a sustainable development, but in some respects they are still not ambitious enough. [ABSTRACT FROM AUTHOR]

In this paper, we compare species description rates to predict the numbers of undescribed species. These data are used to discuss the merits of various attempts to estimate species richness in the oceans. European marine areas. Predictions of how many species may exist on Earth have lacked an inventory of how many have been described, except for a few small taxa. The ocean is a good place to start an inventory because it includes all but one of the phyla and most classes of life on Earth. The European Register of Marine Species (ERMS) was compiled by taxonomic experts, covered all marine taxa, and accounted for synonyms. Reflecting taxonomic history, Europe's species are the best described in the world. ERMS listed 29,713 species of animals, plants and protists, but excluded bacteria and viruses. An estimated 6500 described species were not included. The best prediction of the number of species remaining to be described was 5613. Plots of years when species were first described showed no decrease in the rate of description for any taxa except birds, mammals and krill. If taxonomic effort has increased, whether due to more resources globally or greater efficiencies of productivity, then description rates per unit effort may be declining and the number of undescribed species may be lower than predicted. However, apart from reduced rates of description during the World Wars, there were no changes in description rates that could be easily attributed to such factors. There are about 36,000 species described from European seas, and we predict that 40,000 to 48,000 may exist. This comprises 15% of the estimated 230,000 described marine species. However, this area is well known compared with other seas and the proportion of species yet to be discovered will be higher elsewhere. [ABSTRACT FROM AUTHOR]

Aim: Assuming genetic variants are selectively neutral, estimates of intraspecific genetic diversity and population structure should increase simultaneously in parallel to coalescent time, population size and gene flow. However, other processes, such as genetic drift associated with demographic fluctuations, might cause a loss of genetic diversity while not affecting population structure. In this study, we assess large‐scale patterns of estimates of intraspecific genetic variation across species to determine the roles of dispersal, biogeography, divergence time and demographic fluctuations in decoupling genetic diversity and population structure. Location: Pristine first‐order streams distributed in seven regions from Neotropical to boreal climate, covering a gradient of habitat persistence through major biogeographical changes (e.g., Pleistocene glaciations). Time period: 2008–2010. Major taxa studied: Freshwater insect lineages that differ in dispersal propensity. Methods: Intraspecific nucleotide diversity (π) and population structure (ΦST) were estimated for 33 species using 2,128 sequences of the cox1 gene. The correlation between π and ΦST was tested using linear regression models. The geographical distribution of haplotypes was represented in networks. Phylogenetic trees were time calibrated to determine divergence time. Results: At a global scale, a positive relationship between π and ΦST was found. Neotropical species showed the highest values of π and ΦST, probably owing to historical environmental stability. Across Europe, the low estimates of π and the wide array of ΦST values and haplotype networks found across species, lineages and latitude were contrary to the biogeographical and dispersal paradigms. Main conclusions: Beyond the macroecological trend found, genetic trajectories of co‐distributed temperate species were disassociated from their functional traits and probably caused by persistent demographic fluctuations associated with local‐scale habitat instability. Overall, the idiosyncratic relationship between π and ΦST across species prevents the establishment of conclusive global patterns and questions the phylogeographical patterns established when studying a reduced number of co‐distributed species. [ABSTRACT FROM AUTHOR]

Aim: The stress‐gradient hypothesis (SGH) postulates that species interactions shift from negative to positive with increasing abiotic stress. Interactions between species are increasingly being recognized as important drivers of species distributions, but it is still unclear whether stress‐induced changes in interactions affect continental‐to‐global scale species distributions. Here, we tested whether associations of vascular plant species in dry grasslands in Europe follow the SGH along a climatic water deficit (CWD) gradient across the continent. Location: Dry grasslands in Europe. Time period: Present. Major taxa studied: Vascular plants. Methods: We built a context‐dependent joint species distribution model (JSDM) to estimate the residual associations (i.e., associations that are not explained by the abiotic environment) of 161 plant species as a function of the CWD based on community data from 8,660 vegetation plots. We evaluated changes in residual associations between species for pairs and on the community level, and we compared responses for groups of species with different drought tolerances. Results: We found contrasting shifts in associations for drought‐sensitive and drought‐tolerant species. For drought‐sensitive species, 21% of the pairwise associations became more positive with increasing CWD, whereas 17% became more negative. In contrast, only 17% of the pairwise associations involving drought‐tolerant species became more positive, whereas 27% became more negative in areas with a high CWD. Additionally, the incidence of positive associations increased with drought for drought‐sensitive species and decreased for drought‐tolerant species. Main conclusions: We found that associations of drought‐sensitive plant species became more positive with drought, in line with the SGH. In contrast, associations of drought‐tolerant species became more negative. Additionally, changes in associations of single species pairs were highly variable. Our results indicate that stress‐modulated species associations might influence the distribution of species over large geographical extents, thus leading to unexpected responses under climate change through shifts in species associations. [ABSTRACT FROM AUTHOR]

Aim: Old‐growth, mesic temperate forests are often assumed to be structured by gap‐phase processes, resulting in quasi‐equilibrial long‐term dynamics. This assumption influences management focused on simulation of natural disturbance dynamics and is embedded in most models of forest successional dynamics. We use multi‐decade monitoring of permanent plots in old‐growth forests to assess demographic assumptions directly with respect to tree mortality rates. Location: Sixteen sites in mesic, temperate old‐growth forests in eastern North America and Europe with multi‐decade monitoring. Time period: Variable across sites, spanning c. 20–78 years from 1936 to 2014. Major taxa studied: Tree species of late‐successional, cool‐temperate forests of Europe and eastern North America. Methods: We calculated and compared the annualized mortality rates (m), with confidence intervals, by species, size class and measurement interval, for tree species of sufficient abundance. Results: Retrospective analysis shows dynamic and diverse demographic properties across populations and sites. Stand‐scale mortality rates of 0.7–2.5%/year average higher than previous estimates for old‐growth temperate forests. Variations among species, over time and among size classes, suggest that gap‐phase models are inadequate to explain stand dynamics, implying instead that rare disturbance events of moderate severity have long‐lasting effects in old‐growth forests and that indirect anthropogenic influences affect old‐growth, unlogged forests. Main conclusions: Multi‐decade baseline data, essential for understanding community assembly and long‐term dynamics in these "slow systems," are rare and poorly integrated. Our analysis demonstrates the value of the few long‐term, "legacy" data sets. Results suggest that differences in life history interact with complex disturbance histories, resulting in non‐equilibrial dynamics in old‐growth temperate tree communities, and that changes in disturbance patterns through anthropogenic climate change might, therefore, be an important driver of ecosystem change. [ABSTRACT FROM AUTHOR]

Aim: Climate and land use are key determinants of biodiversity, with past and ongoing changes posing serious threats to global ecosystems. Unlike most other organism groups, plant species can possess dormant life‐history stages such as soil seed banks, which may help plant communities to resist or at least postpone the detrimental impact of global changes. This study investigates the potential for soil seed banks to achieve this. Location: Europe. Time period: 1978–2014. Major taxa studied: Flowering plants. Methods: Using a space‐for‐time/warming approach, we study plant species richness and composition in the herb layer and the soil seed bank in 2,796 community plots from 54 datasets in managed grasslands, forests and intermediate, successional habitats across a climate gradient. Results: Soil seed banks held more species than the herb layer, being compositionally similar across habitats. Species richness was lower in forests and successional habitats compared to grasslands, with annual temperature range more important than mean annual temperature for determining richness. Climate and land‐use effects were generally less pronounced when plant community richness included seed bank species richness, while there was no clear effect of land use and climate on compositional similarity between the seed bank and the herb layer. Main conclusions: High seed bank diversity and compositional similarity between the herb layer and seed bank plant communities may provide a potentially important functional buffer against the impact of ongoing environmental changes on plant communities. This capacity could, however, be threatened by climate warming. Dormant life‐history stages can therefore be important sources of diversity in changing environments, potentially underpinning already observed time‐lags in plant community responses to global change. However, as soil seed banks themselves appear, albeit less, vulnerable to the same changes, their potential to buffer change can only be temporary, and major community shifts may still be expected. [ABSTRACT FROM AUTHOR]

Aim: To investigate spatial gradients in population trends of European birds in relation to their association with farmland, dietary dependence on insects, and the intensity of agricultural practices. Location: Europe. Time period: 2001–2012. Major taxa studied: Birds. Methods: We collected population trends for 197 species in 32 European countries. For the same time period, we used agricultural variables (annual yields of five major crops and the per‐hectare application of pesticides and fertilizers) to express the agricultural intensity level (mean values of variables over the years) and intensification rate (slopes of agricultural variables over the years) in each country. We employed spatial generalized additive mixed models accounting for the effects of 11 species' traits and phylogeny to test for spatial gradients in bird population trends in relation to species' associations with farmland and their diet dependence on insects and the interaction of these traits with agricultural intensity levels and intensification rates. Results: Open‐habitat insectivores showed the strongest spatial gradient in population trends, from insignificant trends in south‐eastern Europe to steep declines in north‐western Europe. Insectivorous species breeding in semi‐open habitats showed very similar but weaker spatial gradient in trends. More negative bird trends were related to higher mean crop yields and fertilizer amounts across countries, whereas the temporal trends in yields and fertilizer amounts, and the mean and temporal trend in the amount of pesticides, were unrelated to bird declines or showed the opposite patterns. Main conclusions: Our results indicate that high agricultural intensity levels are stronger drivers of spatial gradients in population declines of insectivorous farmland birds than intensification rates. Therefore, approaches to the conservation of farmland birds may differ regionally: introducing more management for birds and insects into highly intensive agriculture in north‐western Europe and preventing further intensification in south‐eastern Europe. [ABSTRACT FROM AUTHOR]

Aim: Climate change impacts forest functioning and services through two inter‐related effects. First, it impacts tree growth, with effects, for example, on biomass production. Second, climate change also reshuffles community composition, with further effects on forest functioning. However, the relative importance of these two effects has rarely been studied. Here, we developed a new modelling approach to investigate these relative importances for forest productivity. Location: Eleven forest sites in central Europe. Time period: Historical (1990) and end‐of‐21st‐century climate‐like conditions. We simulated 2,000 years of forest dynamics for each set of conditions. Major taxa studied: Twenty‐five common tree species in European temperate forests. Methods: We coupled species distribution models and a forest succession model, working at complementary spatial and temporal scales, to simulate the climatic filtering that shapes potential tree species pools, the biotic filtering that shapes realized communities and the functioning of these realized communities in the long‐term. Results: Under an average temperature increase (relative to 1901–1990) of between 1.5 and 1.7 °C, changes in simulated forest productivity were caused mostly by changes in the growth of persisting tree species. With an average temperature increase of 3.6–4.0 °C, changes in simulated productivity at sites that currently have a mild climate were again caused predominantly by changes in tree species growth. However, at the warmest and coldest sites, changes in productivity were related mostly to shifts in species composition. In general, at the coldest sites, forest productivity is likely to be enhanced by climate change, whereas at the warmest sites the productivity might increase or decrease depending on the future precipitation regime. Main conclusions: A combination of two complementary modelling approaches that address questions at the interface between biogeography, community ecology and ecosystem functioning, reveals that climate change‐driven community reshuffling in the long term might be crucially important for ecosystem functioning. [ABSTRACT FROM AUTHOR]

Aim: The aim was to decipher Europe‐wide spatio‐temporal patterns of forest growth dynamics and their associations with carbon isotope fractionation processes inferred from tree rings as modulated by climate warming. Location: Europe and North Africa (30‒70° N, 10° W‒35° E). Time period: 1901‒2003. Major taxa studied: Temperate and Euro‐Siberian trees. Methods: We characterize changes in the relationship between tree growth and carbon isotope fractionation over the 20th century using a European network consisting of 20 site chronologies. Using indexed tree‐ring widths (TRWi), we assess shifts in the temporal coherence of radial growth across sites (synchrony) for five forest ecosystems (Atlantic, boreal, cold continental, Mediterranean and temperate). We also examine whether TRWi shows variable coupling with leaf‐level gas exchange, inferred from indexed carbon isotope discrimination of tree‐ring cellulose (Δ13Ci). Results: We find spatial autocorrelation for TRWi and Δ13Ci extending over a maximum of 1,000 km among forest stands. However, growth synchrony is not uniform across Europe, but increases along a latitudinal gradient concurrent with decreasing temperature and evapotranspiration. Latitudinal relationships between TRWi and Δ13Ci (changing from negative to positive southwards) point to drought impairing carbon uptake via stomatal regulation for water saving occurring at forests below 60° N in continental Europe. An increase in forest growth synchrony over the 20th century together with increasingly positive relationships between TRWi and Δ13Ci indicate intensifying impacts of drought on tree performance. These effects are noticeable in drought‐prone biomes (Mediterranean, temperate and cold continental). Main conclusions: At the turn of this century, convergence in growth synchrony across European forest ecosystems is coupled with coordinated warming‐induced effects of drought on leaf physiology and tree growth spreading northwards. Such a tendency towards exacerbated moisture‐sensitive growth and physiology could override positive effects of enhanced leaf intercellular CO2 concentrations, possibly resulting in Europe‐wide declines of forest carbon gain in the coming decades. [ABSTRACT FROM AUTHOR]

Aim The aim was to assess the sensitivity of butterfly population dynamics to variation in weather conditions across their geographical ranges, relative to sensitivity to density dependence, and determine whether sensitivity is greater towards latitudinal range margins. Location Europe. Time period 1980-2014. Major taxa studied Butterflies. Methods We use long-term (35 years) butterfly monitoring data from > 900 sites, ranging from Finland to Spain, grouping sites into 2° latitudinal bands. For 12 univoltine butterfly species with sufficient data from at least four bands, we construct population growth rate models that include density dependence, temperature and precipitation during distinct life-cycle periods, defined to accommodate regional variation in phenology. We use partial R2 values as indicators of butterfly population dynamics' sensitivity to weather and density dependence, and assess how these vary with latitudinal position within a species' distribution. Results Population growth rates appear uniformly sensitive to density dependence across species' geographical distributions, and sensitivity to density dependence is typically greater than sensitivity to weather. Sensitivity to weather is greatest towards range edges, with symmetry in northern and southern parts of the range. This pattern is not driven by variation in the magnitude of weather variability across the range, topographic heterogeneity, latitudinal range extent or phylogeny. Significant weather variables in population growth rate models appear evenly distributed across the life cycle and across temperature and precipitation, with substantial intraspecific variation across the geographical ranges in the associations between population dynamics and specific weather variables. Main conclusions Range-edge populations appear more sensitive to changes in weather than those nearer the centre of species' distributions, but density dependence does not exhibit this pattern. Precipitation is as important as temperature in driving butterfly population dynamics. Intraspecific variation in the form and strength of sensitivity to weather suggests that there may be important geographical variation in populations' responses to climate change. [ABSTRACT FROM AUTHOR]

Aim Understanding the relative contribution of different species interactions in shaping community assembly has been a pivotal aim in community ecology. Biotic interactions are acknowledged to be important at local scales, although their signal is assumed to weaken over longer distances. We examine the relationship between positive, neutral and negative pairwise bird abundance distributions and the phylogenetic and functional distance between these pairs after first controlling for habitat associations. Location France and Finland. Time period 1984 to 2011 (Finland), 2001 to 2012 (France). Major Taxa studied Birds. Methods We used results from French and Finnish land bird monitoring programmes, from which we created three independent datasets (French forests, French farmlands and Finnish forests). Separately for the three datasets, we fitted linear mixed-effects models for pairwise abundance values across years per point count station to infer the association between all common species pairs, while controlling for geographical distribution and habitat associations, and saved pairwise regression coefficients for further analyses. We used a null model approach to infer whether the observed associations (effect sizes) differ from random. Finally, using quantile regression, we analysed the relationships between functional dissimilarity/phylogenetic distance and effect sizes. Results Our results show both negative and positive species interactions, although negative interactions were twice as common as positive interactions. Closely related species were more likely to show strong associations, both negative and positive, than more distant species across broad spatial scales. For functional dissimilarity, the results varied across datasets. Main conclusions Our results emphasize the potential of functional and phylogenetic proximity in generating both negative and positive species associations, which can produce pervasive patterns from local to geographical scales. Future assembly studies should refrain from strict dichotomies, such as compensatory dynamics versus environmental forcing, and instead consider the possibility of positive interactions. [ABSTRACT FROM AUTHOR]

Aim Plant invasions often follow initial introduction with a considerable delay. The current non-native flora of a region may hence contain species that are not yet naturalized but may become so in the future, especially if climate change lifts limitations on species spread. In Europe, non-native garden plants represent a huge pool of potential future invaders. Here, we evaluate the naturalization risk from this species pool and how it may change under a warmer climate. Location Europe. Methods We selected all species naturalized anywhere in the world but not yet in Europe from the set of non-native European garden plants. For this subset of 783 species, we used species distribution models to assess their potential European ranges under different scenarios of climate change. Moreover, we defined geographical hotspots of naturalization risk from those species by combining projections of climatic suitability with maps of the area available for ornamental plant cultivation. Results Under current climate, 165 species would already find suitable conditions in>5% of Europe. Although climate change substantially increases the potential range of many species, there are also some that are predicted to lose climatically suitable area under a changing climate, particularly species native to boreal and Mediterranean biomes. Overall, hotspots of naturalization risk defined by climatic suitability alone, or by a combination of climatic suitability and appropriate land cover, are projected to increase by up to 102% or 64%, respectively. Main conclusions Our results suggest that the risk of naturalization of European garden plants will increase with warming climate, and thus it is very likely that the risk of negative impacts from invasion by these plants will also grow. It is therefore crucial to increase awareness of the possibility of biological invasions among horticulturalists, particularly in the face of a warming climate. [ABSTRACT FROM AUTHOR]

Aims The present-day biogeography of European amphibians has been hypothesized to have arisen from range expansion and recolonization of the northern part of the continent from southern late Pleistocene refugia, such that northern species generally possess large ranges while southerly species are mostly small-ranged. Here we test the hypothesis that these patterns are likely to be underpinned by biological traits associated with dispersal ability. We do this by analysing data for anurans and urodeles, the two main groups of European amphibians. Location Europe. Methods We built a database of biological traits (body size, fecundity, life span, habitat specialization) of European amphibians, excluding island endemics. We mapped the basic macroecological patterns of range size and position, and analysed the causal pathways for range size using structural equation models (SEMs). Results Amphibian species with a small range size are largely restricted to areas in southern Europe associated with putative Pleistocene refugia. Those present in northern Europe are exclusively large-ranged species whose distributions extend all the way from southern Europe. SEMs explained 54% of range size variation for anurans, with long life span and high fecundity being influential explanatory variables, and explained 61% of range size variation within urodeles, with measures of species fecundity being influential. Main conclusions Species that have successfully recolonized the north following deglaciation have the largest ranges for both groups of amphibians. These large-ranged species generally possess traits that indicate the potential for rapid range expansion, with differences apparent in the balance of traits between anurans and urodeles. The traits linked to northern distributions (and large range size) appear to be a mix of r and K traits, indicating that intermediate life-history strategies have proved to be optimal for range expansion into northern regions. These results integrate species biology with geographical history in explaining present-day patterns of species distribution, range size and diversity. [ABSTRACT FROM AUTHOR]

Aim To project the potential European distribution of seven broad habitat categories (needle-leaved, broad-leaved, mixed and mediterranean forest, urban, grassland and cropland) in order to assess effects of land use, climate change and increase in CO2 on predicted habitat changes up to the year 2050. Location Europe. Method We modelled the response of European vegetation to changes in land use, climate and CO2 by combining the land-use model Dyna- CLUE (based on the CORINE land-cover data) and the dynamic vegetation model LPJ-GUESS. Two reforestation options were explored: maintaining the current range of tree species ( EFI) or promoting naturally occurring tree species ( NAT). Climate data from two general circulation models and two SRES scenarios ( A2 and B1) were used. The broad habitat types were classified according to a combination of land use and the dominant plant species. Results Our models predicted that croplands and grasslands are expected to decrease due to land-use change. Although climate change has a negative effect on needle-leaved forest, it is expected to maintain its area or even increase in the EFI reforestation option while mediterranean, broad-leaved and mixed forests are expected to increase markedly. All investigated drivers have shown some effect, but land use is the dominant contributor to broad habitat change except for needle-leaved and mixed which are mainly influenced by climate change. Main conclusions Land use is predicted to have the greatest effect on broad habitat distribution according to our simulations. Hence in most parts of Europe mitigating actions should focus on land-use change rather than climate change. According to our simulation, the effects of the different drivers are not in general additive. In some cases they act synergistically and in some cases antagonistically. The projected habitat changes are a valuable tool for species distribution modelling and are available online. [ABSTRACT FROM AUTHOR]

Aim Mountain regions are particularly well-suited for investigating the impact of climate change on species ranges because they encompass both upper and lower limits of species distribution. Here, we investigate changes in the elevational distribution of dung beetle species ( Coleoptera: Scarabaeoidea) in two separate mountain regions in Europe. Location South-western Alps ( France) and Sierra Nevada ( Spain). Methods We compared historical and current data on dung beetle distributions along elevation gradients for 30 species in the SW Alps and 19 species in the Sierra Nevada. We tested for significant changes between survey periods in three parameters: mean elevation and upper and lower range limits. Results We found up-slope range shifts for 63% and 90% of the species in the SW Alps and Sierra Nevada, respectively. Up-slope range shifts resulted mainly from expansion of upper range limits in the SW Alps and from changes of both range limits in the Sierra Nevada. The magnitudes of range shifts were consistent with the level of warming experienced in each region, but they also reflected the asymmetrical warming observed along the elevation gradients. Smaller changes were observed for species reaching their historical range limits at the higher elevations, associated with a non-significant increase in temperature between periods. Main conclusions The differences observed between regions are related to the geographical position of each mountain range, which determines the characteristics (including thermal tolerance) of the regional species pool, and the level of warming, which determines whether maximum thermal tolerance has been exceeded for the majority of species in the region. Our results highlight the importance of considering both the biogeography of the mountain and the species pool under study when assessing the sensitivity of species to future climate change in mountain regions. [ABSTRACT FROM AUTHOR]

Aim Phylogenetic diversity patterns are increasingly being used to better understand the role of ecological and evolutionary processes in community assembly. Here, we quantify how these patterns are influenced by scale choices in terms of spatial and environmental extent and organismic scales. Location European Alps. Methods We applied 42 sampling strategies differing in their combination of focal scales. For each resulting sub-dataset, we estimated the phylogenetic diversity of the species pools, phylogenetic α-diversities of local communities, and statistics commonly used together with null models in order to infer non-random diversity patterns (i.e. phylogenetic clustering versus over-dispersion). Finally, we studied the effects of scale choices on these measures using regression analyses. Results Scale choices were decisive for revealing signals in diversity patterns. Notably, changes in focal scales sometimes reversed a pattern of over-dispersion into clustering. Organismic scale had a stronger effect than spatial and environmental extent. However, we did not find general rules for the direction of change from over-dispersion to clustering with changing scales. Importantly, these scale issues had only a weak influence when focusing on regional diversity patterns that change along abiotic gradients. Main conclusions Our results call for caution when combining phylogenetic data with distributional data to study how and why communities differ from random expectations of phylogenetic relatedness. These analyses seem to be robust when the focus is on relating community diversity patterns to variation in habitat conditions, such as abiotic gradients. However, if the focus is on identifying relevant assembly rules for local communities, the uncertainty arising from a certain scale choice can be immense. In the latter case, it becomes necessary to test whether emerging patterns are robust to alternative scale choices. [ABSTRACT FROM AUTHOR]

Aim To compare macroecological patterns between bird communities of European cities and regional species assemblages in the surrounding landscape, and to reveal geographical trends in the urbanization of native avifauna. Location Forty-one towns and cities in continental Europe. Methods We compiled data on the species richness and community composition of urban avifauna from 41 European city breeding bird atlases, and of species assemblages comprising nine grid cells (each about 50 km × 50 km) from the EBCC Atlas of European Breeding Birds (hereafter regional assemblages). Species-area relationships ( SARs), latitudinal trends in diversity and the distance decay of community similarity were compared using regression models (generalized linear models). Observed urban communities were compared with randomly assembled ones to reveal systematic effects of the urban environment on native bird communities across Europe. We employed variance partitioning to quantify the relative effect of environmental parameters and the spatial position of cities on species richness. Results The species-area relationships did not differ significantly between cities and regional assemblages. Species richness of both types of communities increased towards higher latitudes, although the relationship was unimodal for regional assemblages, in contrast to cities. The increase in beta diversity with distance was on average less pronounced in cities than in regional assemblages, and was lower between individual cities than between communities of the same size randomly drawn from regional species assemblages. Moreover, average beta diversity was lower in northern cities, which are characterized by a relatively higher proportion of species from regional species pools. Main conclusions The species-area relationship and latitudinal trends are largely congruent between cities and the regional assemblages. However, city avifaunas tend to be relatively more uniform across space, revealing biotic homogenization. Urban communities in northern cities are more uniform as a higher proportion of bird species breeds in cities. [ABSTRACT FROM AUTHOR]

Aim The relationship between isoprenoid emission and hygrophily was investigated in woody plants of the Italian flora, which is representative of European diversity. Methods Volatile isoprenoids (isoprene and monoterpenes) were measured, or data collected from the literature, for 154 species native or endemic to the Mediterranean. The Ellenberg indicator value for moisture ( EIVM) was used to describe plant hygrophily. Phylogenetic analysis was carried out at a broader taxonomic scale on 128 species, and then refined on strong isoprene emitters ( Salix and Populus species) based on isoprene synthase gene sequences ( Isp S). Results Isoprene emitters were significantly more common and isoprene emission was higher in hygrophilous EIVM classes, whereas monoterpene emitters were more widespread and monoterpene emission was higher in xeric classes. However, when controlling for phylogeny, isoprene emission was not associated with EIVM, possibly due to the large presence of Salicaceae among hygrophilous isoprene emitters. Moreover, the distribution of isoprene emitters among EIVM classes was not related to Isp S-based phylogenesis in Populus and Salix, suggesting that the gene has not undergone evolution linked to ecological pressure. In contrast, the monoterpene emission pattern is independent of phylogeny, suggesting that the evolution of monoterpenes is associated with transitions to more xeric habitats. Main conclusions Our results reveal an interesting ecological pattern linking isoprenoids and water availability. We suggest that isoprene is a trait that: (1) evolved in plants adapted to high water availability; (2) is replaced by more effective protection mechanisms, e.g. more stable isoprenoids, in plants adapting to more xeric environments; and (3) being strongly constrained by phylogeny, persists in Salicaceae adapted to more xeric environments. [ABSTRACT FROM AUTHOR]

Aim To reconstruct spatial and temporal patterns of European fire activity during the Holocene and to explore their potential drivers, by relating biomass burning to simulated biotic and abiotic parameters. Location Europe. Methods Holocene fire activity was investigated based on 156 sedimentary charcoal records from lakes and peat bogs across Europe. Charcoal data covering the last 9000 years were statistically compared with palaeoclimate data derived from the Max Planck Institute for Meteorology/ University of Wisconsin-Madison Earth System Model, with vegetation and fire indices simulated with the dynamic vegetation model lpj- guess and with two independent scenarios of past anthropogenic land-cover change. Results The combined sedimentary charcoal records suggest that there was little fire activity during the early and the middle Holocene compared with recent millennia. A progressive increase in fire frequency began around 3500 cal. yr bp and continues into the late Holocene. Biomass burning rose sharply from 250 cal. yr bp onwards, reaching a maximum during the early Industrial Era and then declining abruptly. When considering the whole Holocene, the long-term control of fire is best explained by anthropogenic land-cover change, litter availability and temperature-related parameters. Main conclusions While the general patterns found across Europe suggest the primary role of vegetation, precipitation and temperature-related parameters in explaining fire dynamics during the early Holocene, the increase in fire activity observed in the mid-late Holocene is mainly related to anthropogenic land-cover changes, followed by vegetation and temperature-related parameters. The 20th-century decline in biomass burning seems to be due to increased landscape fragmentation and active fire suppression policies. Our hypothesis that human activities played a primary role in Holocene biomass burning across Europe could be tested by improved palaeoclimate reconstructions and more refined representations of anthropogenic fires in climate and vegetation models. [ABSTRACT FROM AUTHOR]

Aim Bioclimatic envelope models ( BEMs) for seven economically important tree species in Europe were independently validated using a hindcasting approach and fossil pollen records spanning the last 1000 years, including the Medieval Warm Period ( MWP), the Little Ice Age ( LIA) and the 20th century ( PRES). The aim was to determine the accuracy of combining BEMs and palaeoecological data to predict continental-scale changes in distribution, and the availability of fossil data to hindcast economically important species. Location Europe, 11 ° W-33 ° E, 33-72 ° N. Methods Eight types of BEMs were implemented in this study, covering most state-of-the-art modelling techniques. Present and palaeoclimatic data were obtained from the atmosphere-ocean global circulation model ECHO- G. The last millennium was divided into three climatically distinct periods: the MWP ( ad 900-1300), the LIA ( ad 1600-1850) and PRES ( ad 1900-2000). Models were calibrated for each period and validated with climatic and pollen data from the remaining periods. Successfully validated models were projected onto a 1° European grid. Results BEMs were successfully validated with independent data. The average area under the curve statistic showed strong model performance, indicating: (1) the strength of BEMs for modelling current and future distributions and, (2) the potential of fossil pollen records to undertake these approaches. European-scale 1°- gridded maps of probability of occurrence largely agreed with observed 20th-century distributions for most taxa, allowing the construction of past modelled species distributions. Main conclusions Results suggest a high potential for BEMs to be used to model future species distributions, and highlight the importance of palaeoecological data to independently validate these models, taking into account the scales at which these data operate. Although valid, BEMs showed poorer performance with heavily managed species and/or those growing in heterogeneous terrain or with discontinuous distributions. The last millennium in Europe was characterized by an increase in woody crop species and a decline of forest species, suggesting increasing land use by humans. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Species distribution models (SDMs) based on current species ranges underestimate the potential distribution when projected in time and/or space. A multi-temporal model calibration approach has been suggested as an alternative, and we evaluate this using 13,000 years of data. Location Europe. Methods We used fossil-based records of presence for Picea abies, Abies alba and Fagus sylvatica and six climatic variables for the period 13,000 to 1000 yr bp. To measure the contribution of each 1000-year time step to the total niche of each species (the niche measured by pooling all the data), we employed a principal components analysis (PCA) calibrated with data over the entire range of possible climates. Then we projected both the total niche and the partial niches from single time frames into the PCA space, and tested if the partial niches were more similar to the total niche than random. Using an ensemble forecasting approach, we calibrated SDMs for each time frame and for the pooled database. We projected each model to current climate and evaluated the results against current pollen data. We also projected all models into the future. Results Niche similarity between the partial and the total-SDMs was almost always statistically significant and increased through time. SDMs calibrated from single time frames gave different results when projected to current climate, providing evidence of a change in the species realized niches through time. Moreover, they predicted limited climate suitability when compared with the total-SDMs. The same results were obtained when projected to future climates. Main conclusions The realized climatic niche of species differed for current and future climates when SDMs were calibrated considering different past climates. Building the niche as an ensemble through time represents a way forward to a better understanding of a species' range and its ecology in a changing climate. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim A debate exists as to whether present-day diversity gradients are governed by current environmental conditions or by changes in environmental conditions through time. Recent studies have shown that latitudinal richness gradients might be partially caused by incomplete post-glacial recolonization of high-latitude regions; this leads to the prediction that less mobile taxa should have steeper gradients than more mobile taxa. The aim of this study is to test this prediction. Location Europe. Methods We first assessed whether spatial turnover in species composition is a good surrogate for dispersal ability by measuring the proportion of wingless species in 19 European beetle clades and relating this value to spatial turnover (βsim) of the clade. We then linearly regressed βsim values of 21 taxa against the slope of their respective diversity gradients. Results A strong relationship exists between the proportion of wingless species and βsim, and βsim was found to be a good predictor of latitudinal richness gradients. Main conclusions Results are consistent with the prediction that poor dispersers have steeper richness gradients than good dispersers, supporting the view that current beetle diversity gradients in Europe are affected by post-glacial dispersal lags. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim In times of biodiversity crisis, it is extremely important to understand diversity gradients. In particular, the study of the diversity of ecological functions is a key issue for the management of ecosystem integrity. Here we identify areas of low functional diversity of the native fish fauna in European drainage basins and we determine the relative importance of three underlying mechanisms: environmental filtering, geographic isolation and climatic history. Location The European continent. Methods Based on 14 morphological traits that are closely related to fish function (habitat and dietary niches), three independent functional diversity indices [functional richness (FR), functional evenness (FE), functional divergence (FD)] were calculated for 128 European drainage basins with a total of 230 fish species. The indices were standardized for species richness using null models. The patterns of the standardized indices are described and three potentially underlying mechanisms are tested using variance partitioning and multi-linear regression models. Results FR and FD were highest in eastern European drainage basins and in Great Britain and lowest in the Mediterranean. FE patterns were less pronounced. All observed patterns were mainly governed by geographic isolation and present environmental conditions. Within the environmental conditions, average annual temperature and precipitation were good predictors for functional diversity. The role of habitat diversity and size was negligible. Main conclusions Geographic isolation coupled with harsh environmental conditions such as extreme temperatures and low precipitation, as in Mediterranean regions, can lead to low FR and FD. This can be explained by extinction that could not be compensated by re-colonization and high speciation. Due to their high functional redundancy, communities in these areas might better withstand further species extinctions on a small scale. Over the short term, however, their often extremely low FR suggests a less flexible functioning that can hinder their ability to withstand today's rapid environmental and anthropogenic threats. [ABSTRACT FROM AUTHOR]

Aim To determine whether the effect of habitat fragmentation and habitat heterogeneity on species richness at different spatial scales depends on the dispersal ability of the species assemblages and if this results in nested species assemblages. Location Agricultural landscapes distributed over seven temperate Europe countries covering a range from France to Estonia. Methods We sampled 16 local communities in each of 24 agricultural landscapes (16 km2) that differ in the amount and heterogeneity of semi-natural habitat patches. Carabid beetles were used as model organisms as dispersal ability can easily be assessed on morphological traits. The proximity and heterogeneity of semi-natural patches within the landscape were related to average local (alpha), between local (beta) and landscape (gamma) species richness and compared among four guilds that differ in dispersal ability. Results For species assemblages with low dispersal ability, local diversity increased as the proximity of semi-natural habitat increased, while mobile species showed an opposite trend. Beta diversity decreased equally for all dispersal classes in relation to proximity, suggesting a homogenizing effect of increased patch isolation. In contrast, habitat diversity of the semi-natural patches affected beta diversity positively only for less mobile species, probably due to the low dispersal ability of specialist species. Species with low mobility that persisted in highly fragmented landscapes were consistently present in less fragmented ones, resulting in nested assemblages for this mobility class only. Main conclusions The incorporation of dispersal ability reveals that only local species assemblages with low dispersal ability show a decrease of richness as a result of fragmentation. This local species loss is compensated at least in part by an increase in species with high dispersal ability, which obscures the effect of fragmentation when investigated across dispersal groups. Conversely, fragmentation homogenizes the landscape fauna for all dispersal groups, which indicates the invasion of non-crop habitats by similar good dispersers across the whole landscape. Given that recolonization of low dispersers is unlikely, depletion of these species in modern agricultural landscapes appears temporally pervasive. [ABSTRACT FROM AUTHOR]

Aim To test whether the distribution of alien bird impacts varies across bird families and regions of origin, and to investigate whether species traits associated with successful introductions can predict which species will have negative impacts in the new area of introduction. Location Europe and the Mediterranean Basin. Methods Combining historical information and published literature about negative economic, biological and human health impacts, we compared the distribution of impacts among bird families and native origins of bird species for three major types of impact (economic, biodiversity and human health). We examined the relationships between ecological, biological and reproductive characteristics of species and the severity of the impacts. Results The majority of alien species with reported impacts originated from the Afrotropical, Indo-Malayan and Palaearctic biogeographical regions. The distribution of alien bird species in Europe with reported impacts shows a taxonomic bias and largely mirrors patterns of establishment. While most species had primarily either economic or biodiversity impacts, several species in the Anatidae, Corvidae, Passeridae, Phasianidae and Sturnidae families were associated with moderate to serious negative impacts on both economic resources and native biodiversity. After controlling for taxonomic effects, species with the greatest overall impacts were habitat generalists and multi-brooded, while species with smaller bodies and the tendency to form large feeding or roosting flocks were linked with greater impacts on native biodiversity. Main conclusions This study presents the first synthesis of published impact data for alien birds and provides a broad-scale perspective on factors that contribute to their impacts. The results show that accounting for both species traits and taxonomy improves our ability to predict the impacts of alien bird species. Because several species are currently in the early stages of establishment in Europe, there may be an opportunity to limit negative impacts with efforts that promote proactive strategies against species and families possessing the above characteristics. [ABSTRACT FROM AUTHOR]

Aim To assess whether the water availability measures commonly used in species distribution models might be misleading because they do not account for the hydrological effects of changes in vegetation structure and functioning. Location Europe. Methods We compared different methods for estimating water availability in species distribution models with the soil water content predicted by a process-based ecosystem model. The latter also accounted for the hydrological effects of dynamic changes in vegetation structure and functioning, including potential physiological effects of increasing CO2. Results All proxies showed similar patterns of water availability across Europe for current climate, but when projected into the future, the changes in the simpler water availability measures showed no correlation with those projected by the more complex ecosystem model, even if CO2 effects were switched off. Main conclusions Results from species distribution modelling studies concerning future changes in species ranges and biodiversity should be interpreted with caution, and more process-based representations of the water balance of terrestrial ecosystems should be considered within these models. [ABSTRACT FROM AUTHOR]

Aim To deconstruct the biodiversity pattern of the 152 waterbird species breeding in Europe to better understand its multiple causal processes. Location Continental Europe, Iceland and the British Isles. Methods We considered the orders that are typically comprised by swimming, diving or wading birds, which inhabit marshes, fens, peatlands and fresh, brackish or salt waters, including coastal waters. We used the 55 main river basins of Europe as geographical units, and searched for either chorotypes (groups of similar species distributions) or gradual replacement of species throughout the river basins. Chorotypes were recognized by applying a probabilistic classification method to the distributions. Then we used GLM to characterize the extent and the species richness of each chorotype according to energy availability (higher levels of environmental energy favouring the presence of species), climatic stress due to an excess of energy, availability of water, productivity, seasonality and surface area. Results One hundred and forty species significantly aggregate into nine chorotypes. The other 12 species, most of them marine, are centred on Great Britain, dropping away progressively on coasts further away from there. Differences in either the availability of energy or climatic stress significantly characterized the distribution of seven chorotypes comprising 90.8% of the species. Main conclusions Chorotypes are meaningful and useful to deconstruct biodiversity patterns. Our results suggest that energy is the main factor related to the biogeographical patterns of breeding waterbirds in Europe, and provide an insight into regional trends of species richness previously analysed with a habitat-scale perspective. [ABSTRACT FROM AUTHOR]

Aim We analysed the variation of species richness in the European freshwater fauna across latitude. In particular, we compared latitudinal patterns in species richness and β-diversity among species adapted to different habitat types. Location Europe. Methods We compiled data on occurrence for 14,020 animal species across 25 pre-defined biogeographical regions of European freshwaters from the Limnofauna Europaea. Furthermore, we extracted information on the habitat preferences of species. We assigned species to three habitat types: species adapted to groundwater, lotic (running water) and lentic (standing water) habitats. We analysed latitudinal patterns of species richness, the proportion of lentic species and β-diversity. Results Only lentic species showed a significant species–area relationship. We found a monotonic decline of species richness with latitude for groundwater and lotic habitats, but a hump-shaped relationship for lentic habitats. The proportion of lentic species increased from southern to northern latitudes. β-Diversity declined from groundwater to lentic habitats and from southern to northern latitudes. Main conclusions The differences in the latitudinal variation of species richness among species adapted to different habitat types are in part due to differences in the propensity for dispersal. Since lentic habitats are less persistent than lotic or groundwater habitats, lentic species evolved more efficient strategies for dispersal. The dispersal propensity of lentic species facilitated the recolonization of central Europe after the last glaciation. Overall, we stress the importance of considering the history of regions and lineages as well as the ecological traits of species for understanding patterns of biodiversity. [ABSTRACT FROM AUTHOR]

Aim We examine issues of uncertainty regarding the spatial and temporal representativeness of phenological observations using a newly compiled Europe-wide data base of phenological observations for Betula species. Location Europe. Methods A new data base was compiled from national phenological observations covering 15 European countries, with the longest observational periods exceeding several decades for some sites. From this, the spatial and temporal representativeness of phenological observations were evaluated via statistical analysis. Results The results showed that there was a significant and irreducible uncertainty related to the use of data of a single station, which varied from 3 to 8 days depending on the station location. In more continental and northern climatic zones the uncertainty was lower, probably due to faster spring-time weather developments. In mild climatic conditions, the uncertainty of dates of the phenological phases registered by a single station exceeded 1 week. The considerable number of data allowed us to preliminarily estimate the features of some stations, marking them as ‘late’, ‘early’, ‘representative’ or ‘random’, depending on the dates reported by these sites and the corresponding regional means. Main conclusions The uncertainties discovered in single-site phenological observations are significant for virtually any potential application. Possible approaches for handling the uncertainty problem are station pre-averaging and spatial regularization of the data set, pre-selection (down-sampling) or changing the description of the phenomena from deterministic to probabilistic. [ABSTRACT FROM AUTHOR]

Aim To analyse the effects of nine species trait variables on the accuracy of bioclimatic envelope models built for 98 butterfly species. Location Finland, northern Europe. Methods Data from a national butterfly atlas monitoring scheme (NAFI) collected from 1991–2003 with a resolution of 10 × 10 km were used in the analyses. Generalized additive models (GAMs) were constructed for 98 butterfly species to predict their occurrence as a function of climatic variables. Modelling accuracy was measured as the cross-validation area under the curve (AUC) of the receiver–operating characteristic plot. Observed variation in modelling accuracy was related to species traits using multiple GAMs. The effects of phylogenetic relatedness among butterflies were accounted for by using generalized estimation equations. Results The values of the cross-validation AUC for the 98 species varied between 0.56 and 1.00 with a mean of 0.79. Five species trait variables were included in the GAM that explained 71.4% of the observed variation in modelling accuracy. Four variables remained significant after accounting for phylogenetic relatedness. Species with high mobility and a long flight period were modelled less accurately than species with low mobility and a short flight period. Large species (>50 mm in wing span) were modelled more accurately than small ones. Species inhabiting mires had especially poor models, whereas the models for species inhabiting rocky outcrops, field verges and open fells were more accurate compared with other habitats. Main conclusions These results draw attention to the importance of species traits variables for species–climate impact models. Most importantly, species traits may have a strong impact on the performance of bioclimatic envelope models, and certain trait groups can be inherently difficult to model reliably. These uncertainties should be taken into account by downweighting or excluding species with such traits in studies applying bioclimatic modelling and making assessments of the impacts of climate change. [ABSTRACT FROM AUTHOR]

Aim Estimates of abundances and densities of birds and mammals have often been shown to be scale dependent, in that population sizes over large areas are overestimated if extrapolated from surveys of small plots. Previous tests of the mechanisms suggested to cause this decelerating scaling pattern found evidence of a biased choice of small plots in patches of homogeneous habitat. Here we show that negative density–area relationships can also arise as result of not considering plots where individuals of the species or assemblage of interest are absent in surveys of differing spatial resolution. Location We took a complete census of violets ( Viola spp.) in 800 m2 of chalk grassland in Wye, Kent, UK, and used human population censuses for Finnish, Swiss and Italian municipalities, English districts, states of the USA and European countries. Methods We used mixed models of logarithmically transformed number of individuals or densities as a function of area. Results The census of violets shows that by increasing the survey resolution and by not considering plots without individuals, the effectively occupied area diminishes and a negative density–area relationship arises. The finding that negative density–area relationships are also common for people is evidence that the non-random choice of plots in population surveys of varying areas can be responsible for many observed negative density–area relationships. The shallower slope of the people–administrative area relationship for Switzerland and Finland compared with Italy, as well as for England and the USA compared with Europe, confirms that less than proportionate individuals–area relationships can be the consequence of larger plot areas containing a higher proportion of areas without individuals. Main conclusions Densities should be reported together with the effective areas for which they were estimated. It should be clearly conveyed whether or not plots where the surveyed species was absent were included in the density estimation. [ABSTRACT FROM AUTHOR]

Aim Species can respond to global climate change by range shifts or by phenotypic adaptation. At the community level, range shifts lead to a turnover of species, i.e. community reassembly. In contrast, phenotypic adaptation allows species to persist in situ, conserving community composition. So far, community reassembly and adaptation have mostly been studied separately. In nature, however, both processes take place simultaneously. In migratory birds, climate change has been shown to result in both exchange of species and adaptation of migratory behaviour. The aim of our study is to predict the impact of global climate change on migratory bird communities and to assess the extent to which reassembly and adaptation may contribute to alterations. Location Europe. Methods We analysed the relationship between current climate and the proportion of migratory species across bird assemblages in Europe. The magnitude of community reassembly was measured using spatial variation in the proportion of potentially migratory species. Adaptation was inferred from spatial variation in the proportion of potentially migratory species that actually migrate at a specific site. These spatial relationships were used to make temporal predictions of changes in migratory species under global climate change. Results According to our models, increasing winter temperature is expected to lead to declines in the proportion of migratory species, whereas increasing spring temperature and decreasing spring precipitation may lead to increases. Changes in winter and spring temperature are expected to cause mainly adaptation in migratory activity, while changes in spring precipitation may result in both changes in the proportion of potentially migratory species and adaptation of migratory activity. Main conclusions Under current climate change forecasts, changes in the proportion of migratory species will be modest and the communities of migratory birds in Europe are projected to be altered through adaptation of migratory activity rather than through exchange of species. [ABSTRACT FROM AUTHOR]

Aim This study uses a high-resolution simulation of the Last Glacial Maximum (LGM) climate to assess: (1) whether LGM climate still affects the geographical species richness patterns in the European tree flora and (2) the relative importance of modern and LGM climate as controls of tree species richness in Europe. Location The parts of Europe that were unglaciated during the LGM. Methods Atlas data on the distributions of 55 tree species were linked with data on modern and LGM climate and climatic heterogeneity in a geographical information system with a 60-km grid. Four measures of species richness were computed: total richness, and richness of the 18 most restricted species, 19 species of medium incidence (intermediate species) and 18 most widespread species. We used ordinary least-squares regression and spatial autoregressive modelling to test and estimate the richness–climate relationships. Results LGM climate constituted the best single set of explanatory variables for richness of restricted species, while modern climate and climatic heterogeneity was best for total and widespread species richness and richness of intermediate species, respectively. The autoregressive model with all climatic predictors was supported for all richness measures using an information-theoretic approach, albeit only weakly so for total species richness. Among the strongest relationships were increases in total and intermediate richness with climatic heterogeneity and in restricted richness with LGM growing-degree-days. Partial regression showed that climatic heterogeneity accounted for the largest unique variation fraction for intermediate richness, while LGM climate was particularly important for restricted richness. Main conclusions LGM climate appears to still affect geographical patterns of tree species richness in Europe, albeit the relative importance of modern and LGM climate depends on range size. Notably, LGM climate is a strong richness control for species with a restricted range, which appear to still be associated with their glacial refugia. [ABSTRACT FROM AUTHOR]

Aim Global climate change is increasingly influencing ecosystems. Long-term effects on the species richness and composition of ecological communities have been predicted using modelling approaches but, so far, hardly demonstrated in the field. Here, we test whether changes in the composition of bird communities have been influenced by recent climate change. Location Europe. Methods We focus on the proportion of migratory and resident bird species because these groups are expected to respond differently to climatic change. We used the spatial relationship between climatic factors and bird communities in Europe to predict changes in 21 European bird communities under recent climate change. Results Observed changes corresponded significantly to predicted changes and could not be explained by the effects of spatial autocorrelation. Alternative factors such as changes in land use were tested in a first approximation as well but no effects were found. Main conclusions This study demonstrates that global climate change has already influenced the species richness and composition of European bird communities. [ABSTRACT FROM AUTHOR]

Aim To analyse the patterns in species richness and endemism of the native European riverine fish fauna, in the light of the Messinian salinity crisis and the Last Glacial Maximum (LGM). Location European continent. Methods After gathering native fish faunistic lists of 406 hydrographical networks, we defined large biogeographical regions with homogenous fish fauna, based on a hierarchical cluster analysis. Then we analysed and compared the patterns in species richness and endemism among these regions, as well as species–area relationships. Results Among the 233 native species present in the data set, the Cyprinidae family was strongly dominant (> 50% of the total number of species). Seven biogeographical regions were defined: Western Peri-Mediterranea, Central Peri-Mediterranea, Eastern Peri-Mediterranea, Ponto-Caspian Europe, Northern Europe, Central Europe and Western Europe. The highest regional species richness was observed for Central Peri-Mediterranea and Ponto-Caspian Europe. The highest endemic richness was found in Central Peri-Mediterranea. Species–area relationships were characterized by high slope values for Peri-Mediterranean Europe and low values for Central and Western Europe. Main conclusions The results were in agreement with the ‘Lago Mare’ hypothesis explaining the specificity of Peri-Mediterranean fish fauna, as well as with the history of recolonization of Central and Western Europe from Ponto-Caspian Europe following the LGM. The results also agreed with the mechanisms of speciation and extinction influencing fish diversity in hydrographical networks. We advise the use of the seven biogeographical regions for further studies, and suggest considering Peri-Mediterranean Europe and Ponto-Caspian Europe as ‘biodiversity hotspots’ for European riverine fish. [ABSTRACT FROM AUTHOR]

Aim We explored the importance of climate and land cover in bird species distribution models on multiple spatial scales. In particular, we tested whether the integration of land cover data improves the performance of pure bioclimatic models. Location Finland, northern Europe. Methods The data of the bird atlas survey carried out in 1986–89 using a 10 × 10 km uniform grid system in Finland were employed in the analyses. Land cover and climatic variables were compiled using the same grid system. The dependent and explanatory variables were resampled to 20-km, 40-km and 80-km resolutions. Generalized additive models (GAM) were constructed for each of the 88 land bird species studied in order to estimate the probability of occurrence as a function of (1) climate and (2) climate and land cover variables. Model accuracy was measured by a cross-validation approach using the area under the curve (AUC) of a receiver operating characteristic (ROC) plot. Results In general, the accuracies of the 88 bird–climate models were good at all studied resolutions. However, the inclusion of land cover increased the performance of 79 and 78 of the 88 bioclimatic models at 10-km and 20-km resolutions, respectively. There was no significant improvement at the 40-km resolution. In contrast to the finer resolutions, the inclusion of land cover variables decreased the modelling accuracy at 80km resolution. Main conclusions Our results suggest that the determinants of bird species distributions are hierarchically structured: climatic variables are large-scale determinants, followed by land cover at finer resolutions. The majority of the land bird species in Finland are rather clearly correlated with climate, and bioclimate envelope models can provide useful tools for identifying the relationships between these species and the environment at resolutions ranging from 10 km to 80 km. However, the notable contribution of land cover to the accuracy of bioclimatic models at 10–20-km resolutions indicates that the integration of climate and land cover information can improve our understanding and model predictions of biogeographical patterns under global change. [ABSTRACT FROM AUTHOR]

Aim Climate is an important determinant of species distributions. We assess different aspects of risk arising from future climate change by quantifying changes in the spatial distribution of future climatic conditions compared with the recent past. Location Europe. Methods A 10′ × 10′ resolution gridded data set of five climate variables was used to calculate expected changes to the area, distance and direction of 1931–60 climatic conditions under the HadCM3 climate model for four future climate scenarios based on different rates of greenhouse gas emissions (SRES scenarios). Three levels of tolerance ranges determined the thresholds for which future conditions are considered analogous to 1931–60 (pre-warming) conditions. Results For many parts of Europe, areas with pre-warming analogous climate conditions will be smaller and further away in the future than they are now. For any location in Europe, areas with pre-warming analogous mean annual temperature conditions will, on average, be reduced between 23.7% (B1 scenario) and 49.7% (A1FI scenario) by 2100 when assuming a medium tolerance range. The mean distance to these areas will, on average, increase between 272 km (B1) and 645 km (A1FI). These changes are more pronounced for temperature than for water availability variables and also for narrow tolerance ranges compared to wide tolerance ranges. Using a combined measure of both temperature and precipitation variables, areas with prewarming analogous conditions are predicted to be in a more northeasterly direction in the future, but there are considerable regional differences within Europe. Main conclusions The results suggest that, for some parts of Europe, the loss of area with any suitable climatic conditions represents the greatest risk to biodiversity, but in other regions the distances that species may have to move to reach suitable climatic conditions may be a greater problem. Quantifying the distance and direction in analyses of change of climatically suitable areas can add additional information for climate change risk assessments. [ABSTRACT FROM AUTHOR]

Aim To understand the impact of glacial refugia and migration pathways on the modern genetic diversity of Pinus sylvestris. Location The study was carried out throughout Europe. Methods An extended set of data of pollen and macrofossil remains was used to locate the glacial refugia and reconstruct the migrating routes of P. sylvestris throughout Europe. A vegetation model was used to simulate the extent of the potential refugia during the last glacial period. At the same time a genetic survey was carried out on this species. Results The simulated distribution of P. sylvestris during the last glacial period is coherent with the observed fossil data, which showed a patchy distribution of the refugia between c. 40° N and 50° N. Several migrational fronts were detected within the Iberian and the Italian peninsulas, and outside the Hungarian plain and around the Alps. The modern mitochondrial DNA depicted three different haplotypes for P. sylvestris. Two distinct haplotypes were restricted to northern Spain and Italy, and the third haplotype dominated most of the present-day remaining distribution range of P. sylvestris in Europe. Main conclusions During the last glacial period P. sylvestris was constrained under severe climatic conditions to survive in scattered and restricted refugial areas. Combining palaeoenvironmental data, vegetation modelling and the genetic data, we have shown that the long-term isolation in the glacial refugia and the migrational process during the Holocene have played a major role in shaping the modern genetic diversity of P. sylvestris in Europe. [ABSTRACT FROM AUTHOR]

Aims To describe the pattern of mean body size of native mammals in Europe, and to investigate its relationships with environmental predictors related to four hypotheses: (1) dispersal; (2) heat conservation; (3) heat dissipation; and (4) resource availability. Location Continental western Europe and Great Britain. Methods We used range maps to estimate the mean body size (average log mass) of mammals in 386 cells of 12,100 km2 each. Environmental conditions in each cell were quantified using nine historical, climatic and primary production variables. We attempted to tease apart the effects of these variables using correlation, multiple regression and spatial autocorrelation analyses. Results In the part of the continent covered by ice during the Pleistocene, body mass decreases southwards, and annual average temperature explains 73% of the variance in body size, consistent with the heat-conservation hypothesis. However, in warmer, non-glaciated areas the best predictor is an estimate of seasonality in plant production, but it explains only 18% of the variance. Carnivores, omnivores and herbivores show similar relationships, but the pattern for herbivores is substantially weaker than for the other groups. Main conclusions Overall, the relationship between mean body size and temperature is non-linear, being strong in cold environments but virtually disappearing above a temperature threshold. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim We explored the effects of prevalence, latitudinal range and spatial autocorrelation of species distribution patterns on the accuracy of bioclimate envelope models of butterflies. Location Finland, northern Europe. Methods The data of a national butterfly atlas survey (NAFI) carried out in 1991–2003 with a resolution of 10 × 10 km were used in the analyses. Generalized additive models (GAM) were constructed, for each of 98 species, to estimate the probability of occurrence as a function of climate variables. Model performance was measured using the area under the curve (AUC) of a receiver operating characteristic (ROC) plot. Observed differences in modelling accuracy among species were related to the species’ geographical attributes using multivariate GAM. Results Accuracies of the climate–butterfly models varied from low to very high (AUC values 0.59–0.99), with a mean of 0.79. The modelling performance was related negatively to the latitudinal range and prevalence, and positively to the spatial autocorrelation of the species distribution. These three factors accounted for 75.2% of the variation in the modelling accuracy. Species at the margin of their range or with low prevalence were better predicted than widespread species, and species with clumped distributions better than scattered dispersed species. Main conclusions The results from this study indicate that species’ geographical attributes highly influence the behaviour and uncertainty of species–climate models, which should be taken into account in biogeographical modelling studies and assessments of climate change impacts. [ABSTRACT FROM AUTHOR]