Assessing the ecophysiological response of a mountain grassland community to ski slope management through isotopic composition.

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 (C/C) and oxygen (O/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 and in for these species the water surplus on the piste may have affected the plants' gas exchanges.