Reinach, Switzerland
Reinach, Switzerland

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Hanspach J.,Helmholtz Center for Environmental Research | Hanspach J.,Lüneburg University | Schweiger O.,Helmholtz Center for Environmental Research | Kuhn I.,Helmholtz Center for Environmental Research | And 6 more authors.
Ecography | Year: 2014

Species ranges are shaped by both climatic factors and interactions with other species. The stress gradient hypothesis predicts that under physiologically stressful environmental conditions abiotic factors shape range edges while in less stressful environments negative biotic interactions are more important. Butterflies provide a suitable system to test this hypothesis since larvae of most species depend on biotic interactions with a specific set of host plants, which in turn can shape patterns of occurrence and distribution. Here we modelled the distribution of 92 butterfly and 136 host plant species with three different modelling algorithms, using distribution data from the Swiss biodiversity monitoring scheme at a 1 × 1 km spatial resolution. By comparing the ensemble prediction for each butterfly species and the corresponding host plant(s), we assessed potential constraints imposed by host plant availability on distribution of butterflies at their distributional limits along the main environmental gradient, which closely parallels an elevational gradient. Our results indicate that host limitation does not play a role at the lower limit. At the upper limit 50% of butterfly species have a higher elevational limit than their primary host plant, and 33% have upper elevational limits that exceed the limits of both primary and secondary hosts. We conclude that host plant limitation was not relevant to butterfly distributional limits in less stressful environments and that distributions are more likely limited by climate, land use or antagonistic biotic interactions. Obligatory dependency of butterflies on their host plants, however, seems to represent an important limiting factor for the distribution of some species towards the cold, upper end of the environmental gradient, suggesting that biotic factors can shape ranges in stressful environments. Thus, predictions by the stress gradient hypothesis were not always applicable. © 2013 The Authors.


Chen G.,CAS Institute of Botany | Kery M.,Swiss Ornithological Institute | Plattner M.,Hintermann and Weber AG | Ma K.,CAS Institute of Botany | Gardner B.,North Carolina State University
Journal of Ecology | Year: 2013

Imperfect detection can seriously bias conventional estimators of species distributions and species richness. Plant traits, survey-specific conditions and site-specific characteristics may influence plant detection probability. However, the generality of the problems induced by imperfect detection in plants and the magnitude of this challenge for plant distribution studies are currently unknown. We address this question based on data from the Swiss Biodiversity Monitoring, in which vascular plants are surveyed twice in the same year along a 2.5-km transect in 451 1-km2 quadrats. Overall, 1700 species were recorded. We chose a random sample of 100 species from the 1700 species to determine general detection levels. To examine the relationship of covariates on detection, we chose a stratified random sample of 100 species from 886 species that were detected in at least 18 locations, with 25 each from four life-forms (LF): grass, forb, shrub and tree. Using a Bayesian multispecies site-occupancy model, we estimated occurrence and detection probability of these species and their relation to covariates. Based on the random sample of 100 species, detection probability during the first survey ranged 0.03-0.99 (median 0.74) and during the second survey, 0.03-0.99 (median 0.82). Based on the stratified random sample of 100 species, detection probability during the first survey ranged 0.02-0.99 (median 0.87) and during the second survey, 0.01-1 (median 0.89). Detection probability differed slightly among the four LFs. In 60 species, survey season or elevation had significant effects on detection. We illustrated detection probability maps for Switzerland based on the modelled relationships with environmental covariates. Synthesis. Our findings suggest that even in a standardized monitoring program, imperfect detection of plants may be common. With the absence of a correction for detection errors, maps in plant distribution studies will be confounded with spatial patterns in detection probability. We presume that these problems will be much more widespread in the data sets that are used for conventional plant species distribution modelling. Imperfect detection should be estimated, even in distribution studies of plants and other sessile organisms, to better control detection errors that may compromise the results of species distribution studies. © 2012 The Authors. Journal of Ecology © 2012 British Ecological Society.


Roth T.,Hintermann and Weber AG | Roth T.,University of Basel | Kohli L.,Hintermann and Weber AG | Rihm B.,Meteotest | Achermann B.,Federal Office for the Environment FOEN
Agriculture, Ecosystems and Environment | Year: 2013

Nitrogen (N) deposition is a major threat to biodiversity of many habitats in the lowlands. In mountain habitats, however, the effect of N deposition on biodiversity is not well understood. Here, data from the biodiversity monitoring of Switzerland were used to investigate whether high N deposition is negatively related to species richness and community uniqueness of vascular plants and bryophytes in mountain grassland. The total species diversity, as well as the diversity of three subsets of species (i.e. oligotrophic species, eutrophic species and targeted grassland species according to conservation objectives of the Swiss authorities) were analyzed. Overall, the empirical data from the present study indicate that the currently expert-based range of the critical load of N deposition below which harmful effects on sensitive ecosystems should not occur (upper bound is currently at 20kg Nha-1yr-1) is set too large for mountain hay meadows. Negative relations between N deposition and species richness and community uniqueness in mountain grassland were found already at 10-15kg Nha-1yr-1. The results suggest that the negative effect of N deposition on plant diversity is mainly due to a decrease of oligotrophic plant species and to a lesser extent to an increase in eutrophic plant species. While for bryophytes, the decrease of community uniqueness is related to changes in both oligotrophic and eutrophic species. Furthermore, because plant species richness of target species for conservation was negatively related to N deposition, airborne N deposition is likely to defeat conservation efforts in mountain grassland. © 2013 Elsevier B.V.


Gret-Regamey A.,ETH Zurich | Rabe S.-E.,ETH Zurich | Crespo R.,ETH Zurich | Lautenbach S.,University of Bonn | And 2 more authors.
Landscape Ecology | Year: 2014

Marginal land use changes can abruptly result in non-marginal and irreversible changes in ecosystem functioning and the economic values that the ecosystem generates. This challenges the traditional ecosystem services (ESS) mapping approach, which has often made the assumption that ESS can be mapped uniquely to land use and land cover data. Using a functional fragmentation measure, we show how landscape pattern changes might lead to changes in the delivery of ESS. We map changes in ESS of dry calcareous grasslands under different land use change scenarios in a case study region in Switzerland. We selected three ESS known to be related to species diversity including carbon sequestration and pollination as regulating values and recreational experience as cultural value, and compared them to the value of two production services including food and timber production. Results show that the current unceasing fragmentation is particularly critical for the value of ESS provided by species-rich habitats. The article concludes that assessing landscape patterns is key for maintaining valuable ESS in the face of human use and fluctuating environment. © 2013 Springer Science+Business Media Dordrecht.


Schai-Braun S.C.,University of Natural Resources and Life Sciences, Vienna | Weber D.,Hintermann and Weber AG | Hacklander K.,University of Natural Resources and Life Sciences, Vienna
European Journal of Wildlife Research | Year: 2013

The number of European brown hares (Lepus europaeus) has been declining throughout much of Europe since the 1960s. Consequently, many studies have focused on analysing habitat selection of European hares in order to improve the suitability of the habitat for this species. Habitat preferences of European hares are known to be affected by hare density, but most studies have been conducted in agricultural areas where hare densities were medium to high. Finding habitat preferences at high densities is difficult as most available habitats are occupied. In addition, in agricultural areas, field size might influence the hares' habitat selection because it affects the distribution and availability of certain habitat types. However, most studies relate to areas with large field sizes. In this study, we analysed the habitat preferences of European hares in spring and autumn during the activity period, in the early hours of the night, in an agricultural area with low hare density and small average field size using Chesson's electivity index. Moreover, we focused on the question whether two different habitat classifications varying in their specificity might cause contradictory results regarding European hares' habitat preferences. Our results show that in this agricultural area with low hare density, European hares avoided several habitat types which were preferred in other study areas with higher hare densities. Therefore, we assume that hare density has an influence on the species' habitat selection. In contrast, the small average field size of our study area seemed not to have an effect on hare habitat preference. Furthermore, by pooling habitat types into broader groups, substantial information was lost in some categories. Hence, for some categories, e.g. grassland or agricultural crop land, more detail might be needed than for others, such as urban areas, when analysing hares' habitat selection. In conclusion, our results imply that studies on habitat preferences have to be conducted in areas with low hare density to be able to gain knowledge on the species' habitat requirement and hereinafter improve the suitability of the habitat for this species. © 2012 Springer-Verlag Berlin Heidelberg.


Dorazio R.M.,U.S. Geological Survey | Kery M.,Swiss Ornithological Institute | Royle J.A.,U.S. Geological Survey | Plattner M.,Hintermann and Weber AG
Ecology | Year: 2010

A variety of processes are thought to be involved in the formation and dynamics of species assemblages. For example, various metacommunity theories are based on differences in the relative contributions of dispersal of species among local communities and interactions of species within local communities. Interestingly, metacommunity theories continue to be advanced without much empirical validation. Part of the problem is that statistical models used to analyze typical survey data either fail to specify ecological processes with sufficient complexity or they fail to account for errors in detection of species during sampling. In this paper, we describe a statistical modeling framework for the analysis of metacommunity dynamics that is based on the idea of adopting a unified approach, multispecies occupancy modeling, for computing inferences about individual species, local communities of species, or the entire metacommunity of species. This approach accounts for errors in detection of species during sampling and also allows different metacommunity paradigms to be specified in terms of species-and location-specific probabilities of occurrence, extinction, and colonization: all of which are estimable. In addition, this approach can be used to address inference problems that arise in conservation ecology, such as predicting temporal and spatial changes in biodiversity for use in making conservation decisions. To illustrate, we estimate changes in species composition associated with the species-specific phenologies of flight patterns of butterflies in Switzerland for the purpose of estimating regional differences in biodiversity. © 2010 by the Ecological Society of America.


Kery M.,Swiss Ornithological Institute | Gardner B.,U.S. Geological Survey | Stoeckle T.,University of Basel | Stoeckle T.,Ecogenics GmbH | And 2 more authors.
Conservation Biology | Year: 2011

Assessment of abundance, survival, recruitment rates, and density (i.e., population assessment) is especially challenging for elusive species most in need of protection (e.g., rare carnivores). Individual identification methods, such as DNA sampling, provide ways of studying such species efficiently and noninvasively. Additionally, statistical methods that correct for undetected animals and account for locations where animals are captured are available to efficiently estimate density and other demographic parameters. We collected hair samples of European wildcat (Felis silvestris) from cheek-rub lure sticks, extracted DNA from the samples, and identified each animals' genotype. To estimate the density of wildcats, we used Bayesian inference in a spatial capture-recapture model. We used WinBUGS to fit a model that accounted for differences in detection probability among individuals and seasons and between two lure arrays. We detected 21 individual wildcats (including possible hybrids) 47 times. Wildcat density was estimated at 0.29/km2 (SE 0.06), and 95% of the activity of wildcats was estimated to occur within 1.83 km from their home-range center. Lures located systematically were associated with a greater number of detections than lures placed in a cell on the basis of expert opinion. Detection probability of individual cats was greatest in late March. Our model is a generalized linear mixed model; hence, it can be easily extended, for instance, to incorporate trap- and individual-level covariates. We believe that the combined use of noninvasive sampling techniques and spatial capture-recapture models will improve population assessments, especially for rare and elusive animals. ©2010 Society for Conservation Biology.


Roth T.,Hintermann and Weber AG | Roth T.,University of Basel | Roth T.,Research Station Petite Camargue Alsacienne | Plattner M.,Hintermann and Weber AG | And 2 more authors.
PLoS ONE | Year: 2014

As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world. © 2014 Roth et al.


Martinez N.,Hintermann and Weber AG
Bird Study | Year: 2012

Capsule Amount of sparse vegetation show a direct link to reproductive success. Aims To examine the influence of sparse vegetation on clutch size of Common Redstarts Phoenicurus phoenicurus. Methods Clutch size and the amount of sparse ground vegetation within territories were measured. Results Clutch size was positively correlated with the amount of sparse vegetation. Clutches in territories with the highest amounts of sparse vegetation contained approximately one more egg than clutches in territories with the lowest amount of sparse vegetation. Conclusion The presence of sparse vegetation is correlated with clutch size and thus reproductive success. This finding suggests a direct link between habitat degradation through the loss of sparse vegetation and observed population decreases of bare-ground foraging birds. The results strengthen the argument that the implementation of sparse vegetation in agri-environment schemes is likely to improve the breeding success of bare-ground foraging birds, such as Common Redstarts. © 2012 British Trust for Ornithology.


Butterflies (Lepidoptera) have been suggested for environmental monitoring of genetically modified organisms (GMO) due to their suitability as ecological indicators, and because of the possible adverse impact of the cultivation of current transgenic crops. A critical point is the sampling effort to be invested in such a monitoring. Here, we estimated the required sample size necessary to monitor potential effects of genetically modified crops on butterflies (Lepidoptera). We used data from two Swiss long-term butterfly monitoring surveys applying the common transect count method. The two monitoring surveys differed in several basic aspects such as geographical area covered, landscape context and sampling intensity. We carried out prospective power analyses in order to estimate the required sample size to detect effects of differing magnitude on mean species number, total individual abundance, mobility classes of butterflies and selected individual species. The required sample size decreased substantially when effect sizes above 10% were estimated. For example, a sample size of 79 transects would be sufficient to detect changes of 30% in total individual abundance for both survey types. Detecting effects on mean species number would need much less transects. Considerably more samples would be needed to analyze the abundance of single species. Several options are presented to increase statistical power or reduce required sample size, respectively. Also, we recommend to pool species to different mobility classes, and/or analyze patch occupancy of species instead of their individual abundance. The transect count approach is a suitable method for butterfly monitoring, both on a local as well as on a landscape scale. Consequently, both types of Swiss butterfly monitoring schemes are basically suitable for GMO monitoring. If transects are short and restricted to intensely used landscape, even non-professional field workers may yield data sufficient for effective monitoring, which might be relevant with respect to involved costs. © 2011 Elsevier Ltd.

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