Shrub Encroachment Affects the Diversity of Plants, Butterflies, and Grasshoppers on Two Swiss Subalpine Pastures (original) (raw)
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Biodiversity and Conservation, 2013
Summer pastures in the Swiss Alps are currently affected by land-use changes that cause a decrease in biodiversity. Although these habitats make up one-third of the whole Swiss agricultural area, direct payments dedicated to support their management are very low. Current political instruments do not support efforts to conserve the biodiversity in these areas, but a vegetation-based approach such as the one implemented in the permanently utilized agricultural areas is under discussion. However, available studies evaluating the surrogate value of vascular plants for other (particularly animal) taxa have yielded inconsistent results, and very few have been conducted in habitats at high elevations. We investigated the extent to which vascular plants are adequate surrogates for butterfly and grasshopper diversity, examining the congruence of species richness and community similarity in two heterogeneous subalpine pastures in the Swiss Alps. Results at the species richness level (Spearman's rank correlation) varied widely according to the study site and taxa assessed. In contrast, at the community similarity level (Procrustean randomization tests with Bray-Curtis similarity), congruencies between vascular plant and invertebrate taxa were generally highly significant. We therefore recommend the use of community similarity as a basis for estimating biodiversity patterns. Our results suggest that conservation measures aimed primarily at enhancing the floristic diversity of subalpine grasslands are also likely to benefit butterfly and grasshopper diversity, at least at the local scale.
Invasive plants threaten the least mobile butterflies in Switzerland
Diversity and Distributions, 2016
Aim: Biological invasions are today the second-largest global threat for biodiversity. Once introduced, exotic plant species can modify ecosystem composition, structure and dynamics, eventually driving native species to local extinction. Among the groups of organisms, most likely to be directly affected by exotic invasive plants are herbivorous insects, such as butterflies, which strongly depend on plants throughout their life cycle. However, it remains unclear whether invasive plants have a negative or a positive effect on butterfly diversity at a landscape scale. Location: Switzerland. Methods: Using an extensive inventory (393 sites across Switzerland) of both butterfly and invasive plants, we explore the impact of 31 invasive black listed plant species on local butterfly richness. We further identify each butterfly spe-cies' response to invasive plants (i.e. positive, neutral or negative) and analyse the functional and phylogenetic characteristics of these different groups of species. Results: Our results indicate that butterfly richness negatively correlates with an increase in invasive plant richness. When studying the individual response of each butterfly species to the number of invasive plants, we found that no single butterfly is profiting from invasive plant species, while 28 butterfly species (24%) suffer from the presence of invasive plants. We further show that the species negatively affected are on average less mobile than the unaffected species and that they are phylogenetically clustered. Main conclusions: Our results present evidences of the influence of invasive species on other trophic levels and interaction networks. We further highlight that a lack of management efforts for mitigating invasive plant impacts threatens specific sections of the functional and phylogenetic diversity of butterflies.
1998
We examined the diversity of vascular plants, butter¯ies, grasshoppers, gastropods and carabid beetles in three calcareous grasslands in the northwestern Swiss Jura mountains, a habitat type that has decreased dramatically during the recent decades. As many as 58 species (ca 22%) of the 266 collected are listed as threatened in northern Switzerland. The number of threatened species ranged from 27 to 49 per site, and 26 species occurred in only one of the three grasslands. The species richness of butter¯ies and vascular plants correlated positively among the grasslands, while the species richness of other groups did not covary. An index of complementarity indicated that the species compositions (including non-threatened species, and spiders and oribatid mites) of the groups varied greatly among the grasslands. In addition, herbivorous groups were more widely distributed than predators among the three grasslands. Due to this variation in species composition none of the three sites can substitute for the others, if the biodiversity of these grasslands is to be maintained. Furthermore, the taxonomic groups studied are poor indicators of each others' diversity. Consequently, we support the`shopping basket' approach to conservation evaluation, i.e. measuring species richness, species composition and complementarity of several groups instead of just one.
In order to enhance agro-biodiversity, Swiss farmers have to convert 7% of the arable land into low-input habitats, namely ecological compensation areas (ECA). This agri-environmental programme is of high scientific interest as it permits to assess and quantify the effects of farming practices at the local and landscape scales. This study aimed at testing the effects of low-input management of grassland on butterfly diversity at the local and the landscape scale in three Swiss farming regions. Low input grasslands did not have higher butterfly diversity than intensive grasslands, despite higher species richness in one year. However, butterfly assemblages varied according to the landscape pattern, namely the amount of low-input habitats, intensive grasslands, crops and forest in the surrounding landscape, and to the regional localisation. Regional differences can be explained by the type and intensity of agricultural production and by landscape features at the regional scale. Recommendations for further development and regionalization of the Swiss ECA scheme are derived.
PLoS ONE, 2013
In recent decades, pastoral abandonment has produced profound ecological changes in the Alps. In particular, the reduction in grazing has led to extensive shrub encroachment of semi-natural grasslands, which may represent a threat to open habitat biodiversity. To reverse shrub encroachment, we assessed short-term effects of two different pastoral practices on vegetation and dung beetles (Coleoptera, Scarabaeoidea). Strategic placement of mineral mix supplements (MMS) and arrangement of temporary night camp areas (TNCA) for cattle were carried out during summer 2011 in the Val Troncea Natural Park, north-western Italian Alps. In 2012, one year after treatment, a reduction in shrub cover and an increase in bare ground cover around MMS sites was detected. A more intense effect was detected within TNCA through increases in forage pastoral value, and in the cover and height of the herbaceous layer. Immediately after treatment, changes in dung beetle diversity (total abundance, species richness, Shannon diversity, taxonomic and functional diversity) showed a limited disturbance effect caused by high cattle density. In contrast, dung beetle diversity significantly increased one year later both at MMS and TNCA sites, with a stronger effect within TNCA. Multivariate Regression Trees and associated Indicator Value analyses showed that some ecologically relevant dung beetle species preferred areas deprived of shrub vegetation. Our main conclusions are: i) TNCA are more effective than MMS in terms of changes to vegetation and dung beetles, ii) dung beetles respond more quickly than vegetation to pastoral practices, and iii) the main driver of the rapid response by dung beetles is the removal of shrubs. The resulting increase in dung beetle abundance and diversity, which are largely responsible for grassland ecosystem functioning, may have a positive effect on meso-eutrophic grassland restoration. Shrub encroachment in the Alps may therefore be reversed, and restoration of grassland enhanced, by using appropriate pastoral practices.
Revue suisse de …, 1996
Species richness and abundance of vascular plants and several groups of invertebrates (spiders, oribatid mites , diplopods, grasshoppers and bush crickets, ground beetles, butterflies and terrestri al gastropods) were recorded in three calcareous grass lands (Nenzlingen, Movelier and Vicques) in the northw estern Swiss Jura mountains. Species ri chness varied both between taxonomical groups and between sites (species richness ranges: 96-116 vascular plants, 60-66 spiders, 18 oribatid mites at each site, 1-7 diplopods, 10-16 grasshoppers and bush crickets, 19-21 ground beetles, 32-46 butterflies and 15-21 terrestrial gastropods). Species overlap (number of species that occurred at all sites) was relatively large in terrestrial gastropods (59.1 %), butterflies (56.5%), vascular plants (53.8 %) and grasshoppers (47.1 % ), but relatively low in oribatid mites (32.3 %), spiders Manuscripl accepted 16.01.1996.
Conservation Biology, 2000
Because of changes in land use, the quantity of extensively grazed or mown calcareous grasslands and their successional stages have drastically declined over the last few decades in Central Europe. Old fallow land has decreased most. It is often afforested or reconverted into extensively cultivated grassland because extensive cultivation is believed to be favorable for diversity and rare species conservation. The relative importance of fallow calcareous grasslands, however, has not been investigated fully and might be much underestimated. To evaluate the relative importance of extensively grazed pastures, early and old fallow land, and young forest, we examined populations of diurnal butterflies from 14 sites in the Swiss Jura Mountains. We used univariate, multivariate, and qualitative methods to compare the successional stages. The first 2-3 years of succession had little influence on the butterfly fauna. Therefore, pastures and early fallow land were treated as a single "early stage." Old fallow land had significantly higher species richness (ϩ 32%) and heterogeneity (ϩ 65%) and hosted more Red List species (ϩ 48%) than the early stage. Young forest was depauperate in butterfly species. Further, cluster analysis and correspondence analysis showed a close resemblance of the sites of the early stage to each other and a clear difference from the sites of old fallow land. All differences were best explained by the successional age of the sites. Both early stage and old fallow land showed a high proportion (Ͼ 25%) of stage-specific species, but more threatened species were specific to old fallow land. We conclude that up to now the importance of old fallow land has been underestimated in conservation efforts in Central Europe. Contrary to the prevailing opinion, it is at least as important for butterflies as extensively cultivated grassland. Further conversion into forest, a common habitat in the region, should be prevented. Because old fallow land has become exceedingly rare, its inclusion in management plans is urgently needed. Otherwise, we may soon lose a valuable but often overlooked part of our biodiversity.