2005 Volume 22 Issue 2 Pages 113-133
We investigated vegetation, ground water level and fluctuation, topography, peat accumulation and vegetation changes of Shinoro Mire, an isolated peatland remnant of Ishikari Mire, once the largest mire in Japan. Many pools and drainage ditches have been dug in the mire, which is surrounded by asphalt roads, landfilled areas and drainage ditches. We classified vegetation into five herbaceous communities (Moliniopsis japonica-Sphagnum comm.; Phragmites australis comm.; Moliniopsis japonica comm.; Sasa comm.; and Miscanthus sinensis・Sasa comm.) and one forest community (Betula platyphylla var. japonica・Alnus japonica comm.). Vegetation changes were rapidly progressing as a result of drainage. It was observed by aerial photography Moliniopsis japonica-Sphagnum community had formed where the surface peat have been removed. Topographic survey indicates that there are a few places with lateral flow, a result of banking or landfilling. The water level was high in fall, winter and early spring snowmelt season. In the summer season it was lower and its fluctuation was much greater. Consequently the peat from the ground surface to 50cm depth was in a state of decomposition. These results show that the mire environment is threatened and mire is in danger of being lost.
