Seed Rain in Natural Grassland and Adjacent Ski Run in the Swiss Alps: A Preliminary Report

Seed rain was studied during one growing season in an intact high-alpine grassland and in a downhill ski run that had been machine-graded about 26 years earlier. The study plots were located at about 2500 meters above sea level. The number of trapped seeds per square meter in the grassland was significantly larger than in the ski run (930 versus 96, respectively). Alpha diversity in seed rain was about two times higher in the grassland than in the ski run. Seed rain was primarily influenced by site conditions but also varied in space and time, and both the actual number of diaspores and the species composition changed throughout the growing season. Most of the species found in the seed rain occurred in the standing vegetation, but some clearly arrived from outside. Seed rain in both sites was dominated by a few species, and no clear relationships were found between the species abundance in standing vegetation and in the seed rain. The results of this preliminary study contribute to a better understanding of plant behavior in high-alpine sites and will be helpful in planning and implementing restoration work above the timberline.