Sensitivity analysis of snow cover to climate change scenarios and their impact on plant habitats in alpine terrain

In high altitude areas snow cover duration largely determines the length of the growing season of the vegetation. A sensitivity study of snow cover to various scenarios of temperature and precipitation has been conducted to assess how snow cover and vegetation may respond for a very localized area of the high Swiss Alps (2050-2500 m above sea level). A surface energy balance model has been upgraded to compute snow depth and duration, taking into account solar radiation geometry over complex topography. Plant habitat zones have been defined and 23 species, whose photoperiodic preferences were documented in an earlier study, were grouped into each zone. The sensitivity of snowmelt to a change in mean, minimum and maximum temperature alone and a change in mean temperature combined with a precipitation change of +10% in winter and -10% in summer is investigated. A seasonal increase in the mean temperature of 3 to 5 K reduces snow cover depth and duration by more than a month on average. Snow melts two months earlier in the rock habitat zone with the mean temperature scenario than under current climate conditions. This allows the species in this habitat to flower earlier in a warmer climate, but not all plants are able to adapt to such changes.