[M-IS11] Geopark

[MIS11-P02] Geomorphological and geoecological resources in the Tomeyama landslide, Happo-Shirakami Geopark

*Ching-Ying Tsou¹, Hiroki Yamagishi¹, Mei-Fang Tsai², Reona Kawakami³ (1.Faculty of Agriculture and Life Science, Hirosaki University, 2.Faculty of Business Administration, Aomori University, 3.United Graduate School of Agricultural Sciences, Iwate University)

Keywords:landslide, plant community, geoecology, geoscience, geopark

Tomeyama landslide is one of the geosite of Happo-Shirakami Geopark, however, extremely few studies have been conducted with regard to the geomorphological and geoecological aspects of this area. This study aimed to clarify the landslide topography and the relationship between topography and vegetation in the area. Landslide topography was interpreted using a 2.5-m mesh ALOS World 3D topographic data digital surface model (AW3D DSM). Plant species composition and their plant covers were surveyed at 3 plots and 1 plot, each of area of 20 m×20 m, on the upper gentle slope and on the convex foot slope of the landslide, respectively. The landslide occurred on an NW-facing slope, 250 m below a ridge-top, with a 40 m-high horseshoe-shaped landslide scarp. The landslide has a width of 350 m and a length of 450 m, with an area of 0.1 km². Besides, two small scarps can be observed on the main landslide scarp and their corresponding displaced landslide blocks below them, suggesting they were formed by the reactivation of the landslide. In three survey plots on the upper slope of the landslide, approximately 40-55 plant species were confirmed, of which 14-16 plant species are deeply related to the Japanese beech forest. In contrast, species related to the Pterocarya rhoifolia forest were only 2-5 species. In the survey plot at the convex foot slope of the landslide, 70 plant species were confirmed, and 14 and 11 species are deeply related to the Japanese beech forest and Pterocarya rhoifolia forest, respectively. The results suggest that the plant community observed in the investigation plots on the upper slope of the landslide can be judged as belonging to the Japanese beech forest. On the other hand, it is difficult to judge the plant community surveyed on the convex foot slope of the landslide, but whereas more species of plants related to the Pterocarya rhoifolia forest compared to those on the upper slope of the landslide. This difference may be related to environmental factors, such as topography, that affect plant community composition in the area.