Global Change Abstracts The Swiss Contribution - SCNAT

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104 Recent reviews confirm and extend previous observations that elevated carbon dioxide (COD concentrations Stimulate photosyn thesis, leading to increased plant productivity. Elevated CO 2 concentrations tend to reduce the sensitivity of grassland ecosystems to low levels of precipitation but induce progressive nitrogen (N) limitations on plant growth which can be alleviated by supplying a significant external input of N in the form of mineral fertilizer or through the increased use of N-fixing legumes. Other nutrients, such as phosphorus, can act as the main limiting factor restricting the growth response in legumes to atmospheric CO 2 concentration. The botanical composition of temperate grasslands is affected by the rise in atmospheric CO 2 concentration, possibly through a decline in the relaTive abundance of grasses. Elevated CO 2 concentration will also alter the feeding value of herbage to grazers both in terms of fine- scale (for example, crude protein concentration and C:N ratio) and coarse-scale (legumes vs. grasses and C-3- VS. C-4-species) changes. The management guidelines of grasslands will need to be adapted to global atmospheric and climatic changes and to increased variability in climate. Grass and Forage Science, 2007, V62, N2, JUN, pp 127-134. 08.1-175 Conservation of grasshopper diversity in a changing environment Steck C E, Bürgi M, Bolliger J, Kienast F, Lehmann A, Gonseth Y Switzerland Biodiversity , Ecology , Zoology , Agriculture, Soil Sciences Land-use change is a major driver for changes in biodiversity. In this study, we investigated how the objectives of two conservation strategies (largescale conservation of species richness versus conservation of diversity hotspots) can be achieved for grasshopper diversity under different scenarios of environmental change (land-use and climate change). Based on surveys of 95 grasshopper species from 2001 to 2004 recorded by the Swiss Centre for Faunal Cartography, we modelled the actual richness pattern as a function of different environmental variables. The impact of potential future environmental change on species richness was evaluated by applying four land-use scenarios (‘liberalization’, ‘business as usual’, ‘lowered agricultural production’, and ‘complete conversion of intensive open land’) and one climate change scenario. The effects of the scenarios were assessed at the national scale, as well as on small- Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems scale hotspots. Environmental change has considerable effect on grasshopper species richness. At the national scale, the number of grasshopper species decreased under the ‘liberalization’ scenario (-0.24 species per 1 ha pixel) and increased under a climate change scenario (+0.63 species per 1 ha pixel). For most environmental change scenarios, species richness in small-scale hotspots was more negatively affected than on average on the national scale. The response of species richness to the scenarios did not differ significantly between hotspots of endangered and the hotspots of common grasshopper species. We conclude that conservation efforts at the national scale and small-scale hotspot conservation programs should be combined to conserve species richness most successfully. For the long-term conservation of species richness, common species as well as the combined effects of land-use and climate change have to be considered. Biological Conservation, 2007, V138, N3-4, SEP, pp 360-370. 08.1-176 Hotspots and richness pattern of grasshopper species in cultural landscapes Steck C E, Bürgi M, Coch T, Duelli P Switzerland Zoology , Biodiversity , Ecology , Agriculture, Soil Sciences The success of the hotspot approach for biodiversity conservation depends on the spatial scale and the indicator species used. In this study, we investigated grasshopper species richness in Switzerland at a 1 ha resolution including a total of 111 species. We compared the representativeness of common and of endangered grasshopper species for the overall grasshopper species richness and we assessed the efficiency of the hotspot approach for grasshopper conservation. The pattern of overall grasshopper species richness was well represented by both the number of common and the number of endangered grasshopper species. For evaluating the efficiency of different hotspot approaches for conservation, we compared hotspots of common species, hotspots of endangered species (rarity hotspots), and hotspots of all grasshopper species (richness hotspots). Among these hotspot types, richness hotspots not only featured most common grasshopper species, but they even contained more endangered species than the rarity hotspots. The combination of rarity hotspots and hotspots of common species featured more species than the other combinations of hotspot types. However, the gain of combining two hotspot types compared to the single-hotspot approach
Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 105 was low (max. 3 species). About 24% of the species were not contained in any of the hotspots. These grasshopper species require species-specific action plans. As rarity hotspots were located in areas that are rather strongly affected by landscape change, species richness in rarity hotspots may decrease in the future. We conclude that, for grasshoppers, the hotspot approach on the 1 ha scale can be an effective way to conserve a high proportion of species richness. Biodiversity and Conservation, 2007, V16, N7, JUN, pp 2075-2086. 08.1-177 Floral free fall in the Swiss lowlands: environmental determinants of local plant extinction in a peri-urban landscape Stehlik I, Caspersen J P, Wirth L, Holderegger R Switzerland, Canada Plant Sciences , Urban Studies , Biodiversity , Ecology , Agriculture, Soil Sciences 1. Local floras are being depleted by a host of human activities, including habitat destruction and fragmentation, eutrophication, and the intensification of agriculture. Species with particular ecological demands or life-history attributes are more prone to extinction than species with a broader niche. 2. We used an old herbarium from the municipality of Kusnacht (Swiss lowlands) as a historical record for comparison with contemporary plant diversity. This comparison revealed that 17% to 28% of all vascular plants that occurred between 1839 and 1915 were extinct by 2003. 3. Species of different habitats and life-forms had significantly different rates of extinction: wetlands, disturbed sites and meadows lost most species, whereas forests and rocky habitats were least affected; aquatics and annuals were most prone to extinction, geophytes and hemicryptophytes were intermediate, and phanerophytes and chamaephytes were least affected. 4. Species adapted to nutrient-poor soils suffered highest extinction in all habitats, indicating that eutrophication poses an urgent threat to species diversity. Light and soil moisture requirements also had significant effects on extinction, but the direction of the effect varied by habitat. 5. When species were grouped into IUCN categories of the red list of Switzerland, the rank order of the observed extinction matched the red list assignment. 6. Because many of the remaining species had high estimated extinction probabilities and because extinction is often delayed (extinction debt), a substantial part of the remaining flora of Kusnacht is likely to go extinct in the near future. This will increase the dominance of the common species that already comprise 81% of the local flora. 7. The rates and patterns of extinction in Kusnacht are probably representative of surrounding Swiss lowlands and peri-urban landscapes in most developed countries. Studies such as ours can serve as a call for action and form a basis for future monitoring of biodiversity. Journal of Ecology, 2007, V95, N4, JUL, pp 734-744. 08.1-178 Cooccurring Gentiana verna and Gentiana acaulis and their neighboring plants in two swiss upper montane meadows harbor distinct arbuscular mycorrhizal fungal communities Sykorova Z, Wiemken A, Redecker D Switzerland Plant Sciences , Biodiversity , Ecology The community composition of arbuscular mycorrhizal fungi (AMF) was analyzed in roots of Gentiana verna, Gentiana acaulis, and accompanying plant species from two species-rich Swiss alpine meadows located in the same area. The aim of the study was to elucidate the impact of host preference or host specificity on the AMF community in the roots. The roots were analyzed by nested PCR, restriction fragment length polymorphism screening, and sequencing of ribosomal DNA small-subunit and internal transcribed spacer regions. The AMF sequences were analyzed phylogenetically and used to define monophyletic sequence types. The AMF community composition was strongly influenced by the host plant species, but compositions did not significantly differ between the two sites. Detailed analyses of the two cooccurring gentian species G. verna and G. acaulis, as well as of neighboring Trifolium spp., revealed that their AMF communities differed significantly. All three host plant taxa harbored AMF communities comprising multiple phylotypes from different fungal lineages. A frequent fungal phylotype from Glomus group B was almost exclusively found in Trifolium spp., suggesting some degree of host preference for this fungus in this habitat. In conclusion, the results indicate that within a relatively small area with similar soil and climatic conditions, the host plant species can have a major influence on the AMF communities within the roots. No evidence was found for a narrowing of the mycosymbiont spectrum in the two green gentians, in contrast to previous findings with their achlorophyllous relatives. Applied and Environmental Microbiology, 2007, V73, N17, SEP, pp 5426-5434.
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