Abstract
To study natural revegetation in the Tennyogahara Mire, a vegetation survey and mapping by GIS raster method with one meter mesh size was conducted in August 2001. The 127 quadrats obtained in 2001, together with 131 quadrats in 1981 and 1988, were grouped into 12 community types using TWINSPAN analyses in term of coverage of the total 104 presented species. They belonged to pool and hollow (2 types), lawn (6 types, among which three were disturbed and recovering types), and shrub and forest (4 types) vegetation, respectively. According to the new actual vegetation map (7820m^2), the largest community is Carex omiana-Hosta atropurpurea/Hosta rectifolia community (30.1% of the mire area) had decreased since 1988 (it was 33.8% in area). The disturbed and recovering area is 19.5%, which had decreased since 1988 (22.4%, based on a polygon vegetation map of 1988), due to the construction of a boardwalk. In the mire, 73.4% of the total area remains unchanged, 20.1% changed progressively, whereas 6.5% changed retrogressively. 68.1% of the changes occurred in the disturbed area. Rhynchospora yasudana-Cladopodiella fluitans community increased mostly, whereas shrub and forest types did slightly but progressively. The boardwalk has been a great help in preventing the vegetation from being damaged by human treading, thus hastening the natural recovery of the mire vegetation.
