Hiroko Fujita, Yaeko Igarashi, Yukie Kato, Takashi Inoue and Masayuki Takada
Proceedings of the 14th International Peat Congress
carex-livida, mire-formation, mire-vegetation-change, pollen-analysis
Theme I. Inventory, stratigraphy and conservation of mires and peatlands
The Sarufutsu River basin is located in the northernmost region of Hokkaido Island, Japan. This small, 40 km-long river basin consists of several mire systems on the flat plain of its lower and middle stream reaches. In contrast to most other Japanese lowland mires that began to form after the so-called Jomon marine transgression (approximately 5,000- 6,000 years ago), the upper and middle reaches of the basin seem not to have suffered sea water intrusion during the early stages of mire formation. We conducted hand boring of peat and the base layer and high resolution pollen analysis on one of the largest mires in this area. Results of the analyses demonstrate that the peat formation started under freshwater lake conditions about 7000 years ago. The mire vegetation can be divided into 3 stages: shallow lake stage; flood plain stage with alder swamp forest; and bog vegetation stage, which started about 2000 years ago.