アポイ山塊と幌満岳の超塩基性岩植生 : 偽の永久方形区法によって示された植生変化(<特集1>アポイ岳の植物群落-アポイ岳の高山植物群落の現状と将来について-)

抄録

The vegetational changes on sites of ultrabasic rock on both Mt. Apoi and Mt. Horoman, Hokkaido, Japan, were studied using the quasi-permanent quadrat method. As to the vegetation on Mt. Apoi, as shown in the synthesis table, past conditions in 1983 and 1994 and the present condition in 2001 were compared, including the changes in the endangered species Callianthemum miyabeanum. As a result, in the Hypocoerio-Caricetum tenuiformis including the above species, the total number of species, number of species per quadrat, and vegetational cover of the community were clearly decreased. The number of quadrats including flowering plants and dominance of Callianthemum miyabeanum in the community also showed clear decreases, although the constancy of the species showed an increase owing to settlement of the quadrats. On the other hand, with regard to the vegetation on Mt. Horoman, past conditions in 1994 and the present conditions in 2001 were compared in the same way as those for Mt. Apoi. As a result, in the Allium schoenoprasum var. yezomonticola-Viola brevistipulata var. hidakana community and the Hypocoerio-Caricetum tenuiformis, both including Callianthemum miyabeanum, vegetational cover of the community and the number of quadrats including flowering plants of Callianthemum miyabeanum showed clear decreases. The above differences in vegetational changes between Mt. Apoi and Mt. Horoman were considered to correspond to the differences in time length of the activities of illegal flower-pickers. Furthermore, the results obtained by the quasi-permanent quadrat method were compared with those for a limestone plant community including Callianthemum sachalinense subsp. kirigishiense from Mt. Kirigishi, Hokkaido. The quasi-permanent quadrat method is considered to be useful for showing vegetational changes from the viewpoint of conservational biology, although it requires further refinements.