Retreat of Turf Scarps and Extension of Patches of Bare Ground in Alpine Zone of Mt. Kisokoma, Central Japan

Abstract

Mt. Kisokoma is located in the northern part of the central Japanese Alps. On the southwest-facing slope of Mt. Kisokoma, patches of bare ground are well developed. This paper presents the extending direction of the patches of bare ground in relation to wind direction, and seasonal changes in the amount of retreat of turf scarps measured with erosion bars. Extending direction of patches of bare ground correspond to the direction of the prevailing westerly wind, which is dominant throughout the year. The results show that the prevailing wind controls the extension of patches of bare ground. The turf scarps retreated most in the Baiu-season. Strong wind accompanied by heavy rain is observed several times during the season, and rain splash wash seems to be the dominant cause of retreat. Negligible retreat of the turf scarps in winter suggests that the turf scarps are protected by snow beds in winter. In spring and autumn, the combination of needle ice and wind erosion might have caused some retreat of the turf scarps.