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A scarce natural snow cover forces an increasing use of artificial snow on ski slopes and returns a small amount of snowmelt water available to plants outside the pistes at the beginning of the growing season. We tested if the use of artificial snow on the ski slopes and the decreased natural snow cover outside the ski slopes lead to changes in the leaf ecophysiology of dominant species in a ski area located in Northern Italy. Using carbon ( 13 C/ 12 C) and oxygen ( 18 O/ 16 O) stable isotope ratios in plant leaves, we estimated the intrinsic water use efficiency (iWUE) and we speculated about changes in photosynthesis and stomatal conductance. Furthermore, carbon and nitrogen concentration, pigments and dry matter content, and the specific area of leaves were measured. We found a higher iWUE of the plants on the ski slopes than outside, probably because the plants on the ski piste are exposed to a condition close to waterlogging that can lead them to regulate their stomata differently than the plants outside the pistes. This behaviour was observed particularly in Ranunculus acris and in Tussilago farfara, for these species the water surplus on the piste may have affected the plants' gas exchanges.

In the Southern Alps, climate warming induced the use of artificial snow since two decades. In this area, two different ski piste management practices prevail: (1) large and medium ski resorts (M), which guarantee a ski season of four to five months using artificial snow, whereas (2) in the small, local ski resorts (S) it usually lasts two or three months. Our research addresses two main questions: 1) what is the impact of the ski pistes on the physico-chemical properties of the snow, on the soil and on the vegetation of mountain grassland ecosystems and 2) does the impact on the mountain grassland ecosystems change between medium and small ski resorts? Our experimental approach follows a pairwise design of plots on mountain grasslands of the ski pistes and control plots on mountain grasslands outside the pistes, where we examined the snow and soil properties and the vegetation composition. Under the long ski-season management (M) we found a significantly lower soil temperature below the snow cover of the ski pistes than the one below the natural snowpack, but this difference was limited to the period of natural snow cover. Only in M, pistes showed a lower biomass production and species richness in the mountain grassland plant communities compared to the controls, while there was no effect in S. The proportions of plant functional groups' cover changed in both ski resort types between piste and control. The most important factors affecting the observed differences in vegetation between pistes and controls were snow duration, snow and soil chemical properties, with more marked differences in the soil properties in M respect to S. The study concludes that reducing the ski season's length, therefore limiting the artificial snow's input, as in S, is more adequate to minimize the environmental impact in a changing climate., (Copyright © 2019 Elsevier B.V. All rights reserved.)