Snowbeds are more affected than other subalpine–alpine plant communities by climate change in the Swiss Alps

• Published in: Ecology and evolution Vol. 6; no. 19; pp. 6969 - 6982
• Main Authors: Matteodo, Magalì, Ammann, Klaus, Verrecchia, Eric Pascal, Vittoz, Pascal
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.10.2016; John Wiley and Sons Inc; Wiley
• Subjects: Alpine environments; Bedrock; Biodiversity; Climate change; Colonization; Community composition; Composition; cover changes; Decades; diversity; Ecological conditions; ecological indicator values; Ecological monitoring; Elevation; Flowers & plants; Grasslands; Habitats; homogenization; Inventories; Inventory management; Mountains; New species; Nitrogen; Original Research; Plant communities; Plant diversity; Plant populations; Precipitation; Principal components analysis; Rainfall; resurvey study; Seasons; semipermanent plot; Snow; Snow cover; snowmelt; Species composition; Species diversity; Switzerland; Vegetation; Vegetation changes; Alps; Switzerland; Switzerland, Alps Mts; resurvey study; diversity; homogenization; grasslands; semipermanent plot; cover changes; Switzerland; snowmelt; Colonization; ecological indicator values
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.2354

While the upward shift of plant species has been observed on many alpine and nival summits, the reaction of the subalpine and lower alpine plant communities to the current warming and lower snow precipitation has been little investigated so far. To this aim, 63 old, exhaustive plant inventories, distributed along a subalpine–alpine elevation gradient of the Swiss Alps and covering different plant community types (acidic and calcareous grasslands; windy ridges; snowbeds), were revisited after 25–50 years. Old and recent inventories were compared in terms of species diversity with Simpson diversity and Bray–Curtis dissimilarity indices, and in terms of community composition with principal component analysis. Changes in ecological conditions were inferred from the ecological indicator values. The alpha‐diversity increased in every plant community, likely because of the arrival of new species. As observed on mountain summits, the new species led to a homogenization of community compositions. The grasslands were quite stable in terms of species composition, whatever the bedrock type. Indeed, the newly arrived species were part of the typical species pool of the colonized community. In contrast, snowbed communities showed pronounced vegetation changes and a clear shift toward dryer conditions and shorter snow cover, evidenced by their colonization by species from surrounding grasslands. Longer growing seasons allow alpine grassland species, which are taller and hence more competitive, to colonize the snowbeds. This study showed that subalpine–alpine plant communities reacted differently to the ongoing climate changes. Lower snow/rain ratio and longer growing seasons seem to have a higher impact than warming, at least on plant communities dependent on long snow cover. Consequently, they are the most vulnerable to climate change and their persistence in the near future is seriously threatened. Subalpine and alpine grasslands are more stable, and, until now, they do not seem to be affected by a warmer climate. Mountain regions are warming rapidly, and the upward shift of plant species has been observed on many alpine and nival summits. In this study, we address the following question: Are there observable changes also at lower elevations in the subalpine–alpine vegetation? Revisiting 67 old, exhaustive plant inventories in the Swiss Alps after 25–50 years, we show that the magnitude and direction of changes varied across the different plant communities: grasslands were quite stable in terms of plant community composition while snowbeds showed pronounced vegetation changes corresponding to the colonisation of species from surrounding grasslands.