北海道中央部大麓山における植生と土壌の垂直変化

抄録

Altitudinal changes in vegetation and soils were studied on Mt. Dairoku (1459.5m altitude), central Hokkaido, Japan. Three altitudinal vegetation types were recognized on the basis of vegetation similarity and species composition : 1) Pinus pumila scrub, distributed at altitudes exceeding 1250m, which was considered to have formed due to edaphic conditions. 2) Subalpine mixed forest, distributed at altitudes between 700m and 1250m, consisting mainly of Picea jezoensis, Abies sachalinensis and Betula ermanii. 3) Cool temperate mixed forest, distributed at altitudes lower than 700m, consisting of Abies sachalinensis, Picea jezoensis, Betula ermanii and many cool temperate deciduous tree species. Main soil types of the Pinus pumila scrub and subalpine mixed forest were black soil and light-colored black soil. These soils were considered to be paleosols, although their surface horizons showed a tendency for weak podzolization. Brown forest soil corresponded well with the cool temperate mixed forest. Synthetic indices of habitat fertility were provided using the soil chemical properties of horizons A_0 and A, which showed a tendency to become reduced gradually at higher altitudes. Soil chemical properties of horizon A_0 showed clear differences between the three vegetation types, whereas those of horizon A showed a difference between black soil and brown forest soil groups. A close correlation between vegetation and soils was recognized.