十和田火山起源の完新世テフラを母材にする火山灰土壌のプラントオパール分析

概要

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Opal phytolith analysis of Podzolic soils, Brown Forest soils, and Ando soils derived from recent Towada volcanic ashes under different climates and vegetaion was made to study the vegetative histories of the sites. Podzolic soils are developed under Abies mariesii forest with Sasa kurilensis. The present vegetation of Brown Forest soils and Ando soils are Faug crenata with Sasa kurilensis and Quercus serrata-Castanea crenata respectively. The present climate of Brown Forest soils and Ando soils areas belongs to the cool temperate zone (montane and hilly zone) and that of Podzolic soils area to the subfrigid zone (subalpine zone). Podzolic soils are characterized by the dominance of Bambusoid phytolith, containing more conifer origin phytoliths than broad-leaved ones. Brown Forest soils are also dominated by Bambusoid phytoliths, containing more broad-leaved tree origin phytoliths than conifer ones. Phytolith assemblages of the two soil groups suggest they have been formed under the present vegetation. On the other hand, Ando soils are characterized by the dominance of non-Bambusoideae origin phytolith. The phytolith composition indicates the Ando soils in the cool temperate zone developed under grassland vegetation mainly composed of Panicoideae. This suggests the grassland vegetation was probably been kept through the suppression of forest vegetation, the climatic climax of the region, by fire.
1986-12-30