Pollen-Analytical Study on the Vegetational History of the Subalpine Zone in the Northern Tohoku District

Abstract

In order to elucidate the vegetational history of the subalpine zone in the northern Tohoku District, the pollen-analytical study was made on the deposits collected from three moors; Yabitsuyachi moor which is situated in the subalpine coniferous forest zone of the Hakkoda Mountains, and Shirojiyama moor in Mt. Shiroji and Tashirodake moor in Mt. Tashirodake, which are situated in the subalpine deciduous scrub zone.The pollen zones in these three moors were distinguished and correlated based on the sequences of main arboreal pollen and tephrochronology (Fig. 5).The present results show that the subalpine zones of these three mountains were covered by subalpine deciduous scrub mainly consisting of Quercus in 4, 500-3, 000 years B. P. Subsequently, in the Hakkoda Mountains, the subalpine deciduous scrub was replaced by Abies mariesii forest during the time of the last 3, 000 years, but in Mt. Shiroji and Mt. Tashirodake, the scrub has been dominant.