Current vegetation changes in an alpine late snowbed community in the south-eastern Alps (N-Italy)

During the last decades, a significant warming was observed in the Alps, cascading into a decrease in snowfall and snow-cover duration. Within the alpine landscape, snowbed communities are regarded as especially vulnerable to the predicted warmer temperatures and earlier snowmelt time. Albeit snowbeds represent a prominent component of the tundra biome, the current vegetation dynamics of these habitats are not yet well understood. In this study, the changes of vascular species richness, co-occurrence, composition, and abundance were evaluated within a late snowbed in the south-eastern Alps. The study was based on a re-survey of 11 permanent plots after a 6-year period. Species richness and abundance significantly increased and species co-occurrence shifted toward higher species segregation. Moreover, the changes in species richness at different spatial scales were related to different environmental factors, and a change in the proportion between snowbed and non-snowbed plants was found. The results suggest an increasing importance of competitive interaction among species in determining the future structure and composition of this community. In conclusion, there is strong evidence that this snowbed community is not in equilibrium with the current climate, and that changes in floristic composition and functional processes of this habitat are underway.