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While many studies on insect diversity report declines, others show stable, fluctuating or increasing trends. For a thorough understanding of insect trends and their effects on ecosystem functioning, it is important to simultaneously assess insect richness, abundance and biomass, and to report trends for multiple taxa.We analysed insect richness, abundance and biomass data for all insects and for eight insect taxa (Buprestidae, Cerambycidae, Carabidae, other Coleoptera, Aculeata, other Hymenoptera, Heteroptera and Lepidoptera) from 42 sites across Switzerland from 2000 to 2007, representing three major habitat types in Switzerland (agricultural, unmanaged [open and forested] and managed forest habitats). As potential drivers of temporal patterns, we evaluated weather‐ and land‐use‐related factors. As predictors, we included temperature and precipitation as well as the vegetation index and the habitat type, respectively.We found a consistent pattern of stable or increasing trends for richness, abundance and biomass of insects in total and the eight taxa over 8 years. Both overall patterns and six out of eight taxa (except for Cerambycidae and Lepidotpera) showed the highest values in agricultural habitats. However, when accounting for elevation, there was no difference in open habitats regardless of whether they were used agriculturally.Habitat types were the most important predictors, followed by weather‐ and vegetation‐related factors. Modelled responses to mean temperature were unimodal, whereas the standard deviation of temperature showed positive and precipitation negative effects. Longer time series are needed to draw robust inferences and to investigate potential negative effects of future warming. [ABSTRACT FROM AUTHOR]

Recent studies reporting widespread declines in arthropod biomass, abundance and species diversity raised wide concerns in research and conservation. However, repeated arthropod surveys over long periods are rare, even though they are key for assessing the causes of the decline and for developing measures to halt the losses. We repeatedly sampled arthropod fauna in a representative Swiss agricultural landscape over 32 years (1987, 1997, 2019). Sampling included eight study sites in four different semi-natural and agricultural habitat types and different trap types (pitfall, window, yellow bucket) over an annual period of 10 weeks to capture flying and ground dwelling arthropod taxa. In total, we analyzed 58,448 individuals from 1343 different species. Mean arthropod biomass, abundance and species richness per trap was significantly higher in 2019 than in the prior years. Also, species diversity of the study area was highest in 2019. Three main factors likely have contributed to the observed positive or at least stable development. First, the implementation of agri-environmental schemes has improved habitat quality since 1993, 6 years after the first sampling. Second, landscape composition remained stable, and pesticide and fertilizer was constant over the study period. Third, climate warming might have favored the immigration and increase of warm adapted species. Our results support the idea that changes in arthropod communities over time is highly context-dependent and complex. Implications for insect conservation: We conclude that the integration and long-term management of ecological compensation patches into a heterogenous agricultural landscape supports insect conservation and can contribute to stable or even increased arthropod abundance, biomass and diversity. Future studies are needed to clarify interdepending effects between agricultural management and climate change on insect communities. [ABSTRACT FROM AUTHOR]

• We evaluated the effects of forest management cessation on indicator bird species. • Despite great structural variance, strict reserves provided suitable habitat for all species. • For open-forest species habitat suitability temporarily decreased after reserve designation. • Short-term contracts for temporary management cessation may thus negatively affect these species. • New strict reserves should be focused on old, near-natural and structurally diverse forests. Increasing the proportion of unmanaged forests in multi-functional forest landscapes is a primary goal of international and national conservation strategies aiming at restoring natural properties in structurally simplified forests. However, the development of structural features and associated habitat suitability for forest species is largely unknown and even controversially discussed, as the development of newly established reserves is unidirectional and passes through dense maturation stages. This may negatively affect open forest species in the first phase after reserve designation. We evaluated the effects of management cessation on key habitat characteristics of four mountain forest bird species indicative of different structural components: Capercaillie (Tetrao urogallus) , Hazel grouse (Bonasa bonasia) , Three-toed woodpecker (Picoides tridactylus) and Pygmy owl (Glaucidium passerinum) across four mountain regions in Central Europe. Habitat suitability was modelled based on 300 forest sites selected independently of their management status, and predicted to an independent dataset of 42 strictly protected forest reserves in the same regions. We then compared forest reserves to managed forests with species presence or absence with regard to habitat suitability and key habitat structures and related both to the time since reserve designation. For all model species, except Pygmy owl, habitat suitability in forest reserves was significantly higher than in managed forests with species' absence, but not different from managed forests with species presence. For the species associated with open forest structures (Capercaillie, Hazel grouse, Pygmy owl) habitat suitability was significantly related to the "reserve age": reserves in the first three decades after management cessation showed a significant decrease in suitability, which increased afterwards up to the maximally recorded time of 100 years. No such correlation was found for the Three-toed woodpecker associated with deadwood and barkbeetle infestations following temporally unpredictable disturbance events. Structural characteristics varied greatly in abundance and distribution, with open structures being related to the time since reserve designation. We therefore recommend focusing on mature, near-natural and structurally diverse forests when designating new strict forest reserves. [ABSTRACT FROM AUTHOR]

Abstract: Abiotic factors, biotic interactions and dispersal ability determine the spatial distribution of species. Theory predicts that abiotic constraints set range limits under harsh climatic conditions and biotic interactions set range limits under benign climatic conditions, whereas dispersal ability should limit both ends of the distribution. However, empirical studies exploring how these three components jointly affect species across environmental gradients are scarce. Here, we present a study that jointly examines these factors to investigate the constraints of the recruitment of Swiss stone pine (Pinus cembra) at and beyond its upper and lower elevational range limits in the Swiss Alps. We investigated the natural recruitment of pines and additionally conducted seed transplant experiments to test how much abiotic factors (mean summer and winter temperatures, soil moisture), biotic interactions (understorey vegetation cover, canopy cover, seed predation) and/or seed deposition by the spotted nutcracker (Nucifraga caryocatactes) affect pine establishment. We found significant effects of biotic interactions and seed deposition by spotted nutcrackers on the recruitment of Swiss stone pine at both the upper and lower elevational range, but could not detect significant effects of abiotic factors. Importantly, dispersal limitation rather than temperature and soil moisture restricted the recruitment of pines at the upper elevational range. Synthesis. Our study highlights the importance of biotic interactions and dispersal ability in setting the upper range limits of species that have been regarded as mainly controlled by climate. This suggests that potential range shifts of plants in response to climate warming may strongly depend on seed dispersal and biotic interactions and not only on climatic factors. [ABSTRACT FROM AUTHOR]

Primary forests are characterized by high vertical and horizontal stand diversity, which provides habitat for a diverse range of species with complex habitat requirements. Detailed knowledge of related ecological processes and habitat development of primary forest species are essential to inform forest management and biodiversity conservation decisions, but relationships are not well documented. We collected dendrochronological data and inventoried numerous structural elements in permanent plots throughout the primary temperate forests within the Carpathian Mountains. We fit and compared multiple predictive models to quantify the importance of 200 years of natural disturbance dynamics on the occurrence probability of an umbrella species – the capercaillie ( Tetrao urogallus ). We showed that a mixed-severity disturbance regime ranging from low through moderate to high severity disturbances is required to generate diverse forest habitats suitable for capercaillie. The variation in natural disturbance severity and its timing promoted key structural habitat elements, such as low natural regeneration density, low mature tree density, high ground vegetation cover, availability of forest gaps, and abundance of standing deadwood. This study demonstrates the importance of natural disturbance in maintaining the variety of conditions necessary to support primary forest specialist species. Managers of protected areas should be mindful that natural disturbances generate habitat for the capercaillie in mountain Norway spruce forests. Further intervention is unnecessary. Conservation planning and forest reserve design should shift focus to the large-scale spatial requirements needed to ensure that a wide range of forest developmental phases are represented in protected areas. [ABSTRACT FROM AUTHOR]

Aim The aim was to investigate the relationship between climate, topography and soil pH, as well as vegetation structure and the beta diversity of plants, butterflies and birds; and to investigate the correlations of (woody) plant beta diversity with animal beta diversity. Location Switzerland (central Europe). Methods We used pairwise Sørensen dissimilarity as measure of total beta diversity and partitioned it into its turnover and nestedness components. Variation partitioning was used to assess the independent and cumulative effects of environmental predictors, with vegetation structure being derived from airborne light detection and ranging (LiDAR) data. We also checked for independent effects of plant and woody plant beta diversity on butterfly and bird beta diversity, respectively, and for independent effects of spatial distance on beta diversity. Results Climate emerged as the strongest statistical predictor of beta diversity across taxonomic groups, with large independent effects on species turnover. Climate effects were most pronounced for plants, followed by butterflies and birds. We also found large independent effects of vegetation structure on total beta diversity and its turnover component across taxonomic groups, particularly for birds. Plant and woody plant beta diversity substantially improved the predictions of butterfly and bird beta diversity, respectively. Spatial distance had hardly any independent effect on beta diversity. Main conclusions Climate is a stronger filter for plant communities than for butterfly and bird communities, which are more affected by vegetation structure, probably owing to associated resources and niches. Vegetation structure is a crucial predictor of beta diversity, and therefore contiguous and detailed 3-D habitat structure data are highly relevant to further our understanding of niche-based community assembly. Plant and animal beta diversity appear to be non-independent, suggesting that differences in the response times of interacting taxa should be accounted for in environmental change impact assessments on biodiversity. [ABSTRACT FROM AUTHOR]

Habitat use of prey species is often subjected to strong trade-offs when foraging needs and predator avoidance cannot be met simultaneously. Trade-offs may be particularly pronounced for species dwelling above ground throughout the year. Identifying habitat use of such species may help to determine crucial and limited environmental resources and has strong implications for habitat management. We investigated the relative importance of habitat structure and composition for mountain hares in the Swiss Alps at the small scale for two time periods, throughout the year and during the reproductive period. Habitat use was assessed by a non-invasive approach that considers the spatio-temporal distribution of fecal pellets, sampled along systematically distributed transects. We found that heterogeneous habitats with high diversity of vegetation layers and/or abundance of saplings and storeyed vegetation structures are strongly used. The availability of shelter was more important in summer when hares strongly used dense habitats that offered protection from predators. The availability of food was more important as predictor for year-round use compared to the reproductive period when food is overabundant for hares. A heterogeneous habitat provides an optimal distribution and availability of shelter and food resources and allows the hare to adjust its activity pattern to changing environmental conditions. Therefore, the occurrence of a structurally heterogeneous ecotone at the upper timber line with a mosaic of different vegetation types and hiding structures should be considered in the management of the species. [ABSTRACT FROM AUTHOR]

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A major conclusion of studying metapopulation biology is that species conservation should favor regional rather than local population persistence. Regional persistence is tightly linked to size, spatial configuration and quality of habitat patches. Hence it is important for the management of endangered species that priority patches can be identified. We developed a predictive model of patch occupancy by capercaillie, a threatened grouse species, based on a single snapshot of data. We used logistic regression to predict patch occupancy as a function of patch size, isolation, connectivity, relative altitude, and biogeographical area. The probability of a patch being occupied increased with patch size and increasing altitude, and decreased with increasing distance to the next occupied patch. Patch size was the most important predictor although occupied patches varied considerably in size. Our model only uses data on the number, size and spatial configuration of habitat patches. It is a useful tool to designate priority areas for conservation, i.e. large core patches with high resilience in habitat quality, smaller island-patches that still have high probability of being inhabited or becoming recolonised, and patches functioning as 'stepping stones'. If capercaillie is to be preserved, habitat suitability needs to be maintained in a functional network of patches that account for size and inter-patch distance thresholds as found in this study. We suggest that similar area-isolation relationships are valid for almost any region within the distribution range of capercaillie. The thresholds for occupancy are however likely to depend on characteristics of the respective landscape. The outcome of our study emphasises the need for future investigations that explore the relationship between patch occupancy, matrix quality and its resistance to dispersing individuals. [ABSTRACT FROM AUTHOR]

The Hazel Grouse ( Bonasa bonasia) has suffered from habitat loss due to changes in forestry practices in many regions of Europe. The widespread conversion of structurally heterogeneous to uniform, single-layered stands has caused many of its populations to decline. The trend in multi-functional forestry towards more dynamic processes and natural rejuvenation offers a unique opportunity to restore many habitats of Hazel Grouse in core areas of its actual distribution. As the Alps represent a stronghold of Hazel Grouse distribution in Central Europe, we aimed to determine the species-habitat relationship in mountain forests. We assessed the distribution and characteristics of Hazel Grouse habitat in a forest reserve of the Swiss Alps. Abiotic, structural and vegetation characteristics were investigated at the small scale, and abiotic and forest inventory data at the large scale. We compared the habitat characteristics of used and unused forest stands with a raster system consisting of bird presence and absence cells by applying a logistic regression. Hazel Grouse preferred stands with high proportions of tall rowans, forest edges, and a dense shrub layer at the small scale. Rowans had the strongest influence on Hazel Grouse occurrence. At the large scale, Hazel Grouse preferred forests with large proportions of alder and a diverse mosaic of canopy closure and stand structure. For 44% of the study area, the large-scale model predicted a probability of Hazel Grouse occurrence of more than 0.5. Our data supports the recommendation that the availability of suitable habitat for Hazel Grouse can be increased by natural reforestation of tree-fall gaps and stands with bark beetle infestation, as well as by enhancing the proportion of old-growth stands. Both measures will augment the shrub cover and number of rowan trees, two essential habitat and food resources for Hazel Grouse in mountain forests. [ABSTRACT FROM AUTHOR]

An increasing number of species are becoming threatened by habitat loss and fragmentation. Therefore, solid estimates of the species' abundance in the remaining populations are required to develop suitable conservation measures and to monitor their effectiveness. The capercaillie (Tetrao urogallus L.) has experienced a dramatic decline in central Europe and has disappeared from large areas of its former natural range. In Switzerland, the species' distribution, habitat requirements and demographic status were studied and evaluated in an attempt to support appropriate management decisions to conserve the species. National surveys of the capercaillie in Switzerland have traditionally been obtained from male counts at leks. However, individual attendance to the lek is sex- and agespecific. Thus, male counts at leks may provide a biased estimate of local population sizes. In the present study, we compared two alternative indirect methods to estimate the sizes of local populations at eight study sites situated in the Alps and Prealps of Switzerland. We first assessed the sizes of local populations from the observed density and distribution of direct and indirect evidence of the species' presence during field surveys. Feather and faeces samples collected during field surveys were genotyped at twelve nuclear microsatellite loci and a sex-specific nuclear gene fragment. Individual genotypes were used as genetic tags to estimate the sizes of the eight local populations using an urn model developed for small populations. The index of local population sizes assessed from field surveys was lower than the number of unique genotypes at each study site, which itself underestimated the abundances of populations in most cases. Based on our results, the genetic tagging method appeared to be less biased than the field survey method. However, an alternative faeces sampling scheme, resulting in 2-3 genotypings per individual, could further improve the accuracy of the size estimates of local populations. Our study confirms that genetic tagging methods are a valuable tool to estimate the sizes of local populations and to monitor the response of rare and elusive species to management actions. [ABSTRACT FROM AUTHOR]

Predictive habitat distribution models are normally assumed to sacrifice generality for precision and reality. Nevertheless, such models are often applied to predict the distribution of a species outside the area for which the model has been calibrated. We investigated how the geographic extent of the data used for calibration influenced the performance of habitat distribution models applied on independent data. We took a multi-scale logistic regression approach by varying the grain size to develop six habitat models for capercaillie Tetrao urogallus in Switzerland: three regional models, for the northern Pre-Alps, eastern Central Alps and Jura mountains, respectively, and three pooled models, each using data from two of the three regions. The six models were validated with data from the region(s) not used for model building. We used Cohen's Kappa and the area under the receiver operating characteristics curve as accuracy measures. The regional models performed well in the region where they had been calibrated, but poorly to moderately well in the other regions. The pooled models classified almost as well in their calibration regions as the corresponding regional models, but generally better when validated on data from the independent region. Hence, models built with data from single regions provide less certain predictions of species’ distributions in other regions. We recommend building more general models using data pooled from several regions, when the aim is to predict species’ distributions in independent regions. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the small-scale habitat selection of capercaillie (Tetrao urogallus) with respect to forest stand composition and topographic characteristics in managed alpine forests of the central Alps in eastern Switzerland. In 12 study areas, we compared 184 study plots in forests stands used (presence) or unused (absence) by the species in spring. A logistic regression model with four predictor variables correctly classified 68.5% of the study plots for capercaillie presence or absence. The model was validated with a 5-fold data-splitting procedure. Four forest stand variables significantly contributed to the model: canopy cover, field-layer cover, the number of basal-branched solitary trees and stand structure. We could not confirm a direct response of capercaillie to bilberry cover in the study areas although bilberry was more abundant in presence plots. Our model is a practical tool for forest managers in the central Alps to assess the abundance and distribution of suitable habitat patches, to monitor trends in habitat suitability dynamics, and to increase the vegetation-related carrying capacity for capercaillie by improving vegetation structure. Suitable capercaillie habitat is characterised by an intermediate canopy cover (30–60%), a well-developed field-layer and the presence of several basal-branched solitary trees. The model is partly based on forest stand variables used in national and regional inventories. However, the inventories would be improved for conservation purposes if information on basal-branched solitary trees as well as field-layer type and composition, preferably the abundance of Ericaceae, Vaccinium and Rubus species, were also collected. [Copyright &y& Elsevier]

Detailed information about three-dimensional vegetation structure proves increasingly useful for studying species-habitat relationships in forest ecosystems. This particularly applies to species that make extensive use of the three-dimensional habitat space in forests, such as bats. Bats show considerable variation in flight morphology and echolocation traits that are shaped by habitat features, and are excellent model taxa for investigating relationships between vegetation structure and animal occurrence and movement. The aims of this study were (1) to investigate the relationship between the activity of bats and forest structure and (2) to compare the performance of airborne Light Detection and Ranging (LiDAR) and terrestrial field surveys for measuring habitat features in a representative sample of mixed and deciduous forests in the Swiss lowlands. Leaf-on and leaf-off LiDAR data were used separately, as well as in combination, to evaluate the relative strength of these datasets to describe 3D canopy architecture and vertical forest structure. Field measurements included structural variables such as leaf area index (LAI), vertical layering, snags, as well as shrub and ground vegetation cover. We recorded 145,433 echolocation call sequences from bats and assigned them into three echolocation guilds (short-, mid- and long-range echolocators; SRE, MRE, LRE, respectively) treating separately the dominant species ( Pipistrellus pipistrellus ; Pp). We used generalized linear mixed models (GLMMs) and applied an information-theoretic approach to assess relationships between guild-specific activity patterns of bats and forest structure in the forest interior, as well as in forest gaps. Standardized coefficients were used to evaluate variable effect sizes and relative importance. We found that guild-specific bat activity was clearly related to 3D forest structure. The activity of SRE, MRE and Pp bats was negatively affected by foliage height diversity, indicating that a large scatter of vegetation elements along 3D forest profiles may restrict accessibility for manoeuvrable bats. Outer canopy surface ruggedness was significantly and positively related to the activity of MRE and LRE bats, as well as Pp, all of which may profit from increased canopy surface ruggedness for foraging (food abundance) and commuting (cover) purposes. The highest variable effect sizes were obtained by combining leaf-on and leaf-off LiDAR data. Leaf-off outperformed leaf-on data, particularly in describing foliage height diversity. LiDAR provided information about bat habitat structure in forests that is not readily available from field surveys. LiDAR thus increases the scope of inference for future investigations of how species respond to vegetation structure, which can now readily and contiguously be assessed at relevant grain sizes and across large areas. [ABSTRACT FROM AUTHOR]

Abstract: River engineering and the subsequent loss and fragmentation of riparian habitats during recent centuries have had serious impacts on the distribution and population size of many riverine species. Thus it is important to identify the characteristics of semi-natural river systems that still support functional connectivity for vulnerable species. Chorthippus pullus is a critically endangered grasshopper that inhabits patches of gravel banks along Alpine river systems. The species’ distribution conceptually resembles a metapopulation. We analysed the patch occupancy and gene flow of a C. pullus population in a river system that had been historically drained in 1923 and improved 67years later by allowing residual water flow. In 2010, we surveyed a total of 43 patches for occupancy, marked and recaptured 299 individuals and analysed DNA samples of 16 local populations using five microsatellite markers. We further correlated a measure of gene flow to landscape resistance matrices using least-cost-path modelling of the contemporary landscape. Our results show that occupancy patterns are positively related to habitat area and connectivity. Gene flow was restricted by forests and large river streams in the contemporary semi-natural situation. The observed high level of genetic diversity is potentially the result of the historical management over several decades. To preserve functional connectivity and gene flow among local populations of critically endangered gravel grasshoppers, habitat availability and suitability have to be maintained by ensuring appropriate temporal and spatial fluctuations in water level. [Copyright &y& Elsevier]