PubMed | University of Basel, Federal Office for the Environment FOEN, Hintermann & Weber AG and Meteotest
Type: Journal Article | Journal: Environmental pollution (Barking, Essex : 1987) | Year: 2016
To protect ecosystems and their services, the critical load concept has been implemented under the framework of the Convention on Long-range Transboundary Air Pollution (UNECE) to develop effects-oriented air pollution abatement strategies. Critical loads are thresholds below which damaging effects on sensitive habitats do not occur according to current knowledge. Here we use change-point models applied in a Bayesian context to overcome some of the difficulties when estimating empirical critical loads for nitrogen (N) from empirical data. We tested the method using simulated data with varying sample sizes, varying effects of confounding variables, and with varying negative effects of N deposition on species richness. The method was applied to the national-scale plant species richness data from mountain hay meadows and (sub)alpine scrubs sites in Switzerland. Seven confounding factors (elevation, inclination, precipitation, calcareous content, aspect as well as indicator values for humidity and light) were selected based on earlier studies examining numerous environmental factors to explain Swiss vascular plant diversity. The estimated critical load confirmed the existing empirical critical load of 5-15kgN ha
Lang A.,University of Basel |
Buhler C.,Hintermann & Weber AG |
Dolek M.,Buro fur Okologische Forschung und Planung |
Roth T.,Hintermann & Weber AG |
Zughart W.,Federal Agency for Nature Conservation BfN
Journal of Insect Conservation | Year: 2016
Setting up effective survey strategies for biodiversity monitoring in agro-ecosystems is a major task in order to detect adverse effects on biodiversity before negative changes will manifest. Here, we studied the relative costs required for the monitoring of butterflies and selected diurnal moths (Papilionoidea et Hesperioidea; Zygaenoidea: Zygaenidae) in farmland. Analysing data from a well-established Lepidoptera monitoring system in Switzerland, we assessed the influence of inspection periods, inspection frequency and transect length on counts of diurnal Lepidoptera. Furthermore, we estimated the number of transects in relation to sampling effort necessary to detect changes of a given effect size for recorded species number (and abundance). Reducing the counting frequency from seven to four inspections per season still yielded 80–90 % of the species, as long as peak abundances in summer months were included. The variation in observed species number was mostly independent of inspection frequency, but strongly increased when transect length was reduced to less than 1 km. Sedentary Lepidoptera species are especially valuable indicators as their occurrences are directly linked to local effects on biodiversity, and the proportion of recorded sedentary species was not substantially affected by reduced inspection frequency. Transects of 1–1.5 km length were generally the most cost-efficient to detect an effect on total species number of diurnal Lepidoptera in arable landscapes, given that travelling distances between transects were short. Studying effects on rare species or selected species groups would involve higher sampling intensity and costs. Surveying schemes with reduced inspection frequency and transect lengths can detect changes in species richness and total abundance of diurnal Lepidoptera cost-effectively. Facing expected changes in agricultural policy and management, the results and recommendations presented here will help to implement and improve cost-efficient Lepidoptera schemes to monitor changes in arable landscapes. © 2015, Springer International Publishing Switzerland.
Nussberger B.,University of Zürich |
Wandeler P.,University of Zürich |
Weber D.,Hintermann & Weber AG |
Keller L.F.,University of Zürich
Conservation Genetics | Year: 2014
Introgression is an important evolutionary force, which can lead to adaptation and speciation on one hand, but on the other hand also to genetic extinction. It is in the latter sense that introgression is a major conservation concern, especially when domestic species reproduce with their rare wild relatives. Hence, monitoring introgression in natural populations subject to hybridization is crucial to elucidate the threat represented by introgression. Here, we monitored introgression between wildcats (Felis silvestris silvestris) and domestic cats (Felis silvestris catus) in a wildcat population in the Swiss Jura Mountains using systematically and non-invasively collected hair samples. We found 21 % admixed individuals based on 68 diagnostic nuclear SNP-markers, corresponding to a migration rate from domestic cats to wildcats of 0.02 migrants per generation. In contrast, gene flow from wildcats into domestic cats was negligible. Haphazard sampling of the same wildcat population, mostly via road kills, led to similar results. Hybridization occurred between wildcat male and domestic cat female and vice versa and, based on the occurrence of backcrosses, both female and male F1-hybrids seem viable and fertile. The observed hybridization pattern may indicate an expanding wildcat population with introgression as a byproduct of this expansion but alternative explanations cannot be excluded with the current data. © 2014, Springer Science+Business Media Dordrecht.
Strebel N.,Hintermann & Weber AG |
Buhler C.,Hintermann & Weber AG
Alpine Botany | Year: 2015
Land abandonment and intensification of management have been suggested as major drivers of biodiversity change in subalpine and alpine grasslands, but the relative importance of these concomitant trends has not been extensively studied. Here, we use plant indicator values to infer patterns of change in the management intensity of summer pastures. Occurrence data of vascular plants from 192 plots surveyed in the Swiss Biodiversity Monitoring BDM programme were used to analyse changes in five species-based indicator values that express the management intensity of sites. Each plot was surveyed twice between 2002 and 2011 with a time span of 5 years between surveys. We looked for an overall trend in management intensity and examined whether a supposed change of management intensity depends on site conditions. In addition, we tested whether a change in indicator values for management intensity accompanies a change in species richness. Over the whole study area, there was no overall change in mean indicator values. However, we found weak but significant relations between changes in mean indicator values and accessibility of the sites. According to plant indicator values, intensification of management takes place at well-accessible and lower-elevation sites, whereas remote sites and sites at higher elevation tend to show a decrease in management intensity. Sites where indicators suggested intensified management showed a decrease of both total species richness and richness of target species relevant for conservation. On the other hand, a supposed decrease in land-use intensity led to an increase in species richness within the surveyed time period. This study confirms that moderate management intensity of summer pastures will best maintain the plant diversity of alpine summer pastures. Because the surveyed plots stem from a rigorously standardized regular-grid sampling, we attribute high reliability and generality to our findings. © 2015, Swiss Botanical Society.