[M-GI20] Environmental changes in mountainous area

[MGI20-P03] The environmental condition of small subalpine coniferous forest on Mt. Aomatsubayama, northern Japan

*Asaka Konno¹ (1.Graduate School of science, Tohoku University)

Keywords:Coniferous forest, Abies mariesii, Location environment, Landform, Soil condition

The coniferous forest (largely composed of Abies mariesii) is presently the typical vegetation of the subalpine zone in Japan. However, around Mt.Aomatsubayama, Kitakami Mountains in northern Japan, the expected predominance of A. mariesii is not extensively observed, and the predominant vegetation is instead the dwarf bamboo (Sasa kurilensis) grasslands and broad leaf forests. It’s called Pseudo-Alpine zone. However it is unknown why the area under coniferous forest is small in this region. The clarification of the reason why small A.mariesii forest formed will make a major contribution the understanding of Pseudo-Alpine zone.The purpose of this study is to clarify the environmental condition of small A. mariesii forests in Mt.Aomatsubayama from the perspectives of distribution of vegetation; geomorphic characteristics; soil conditions.
In this site, there are few mixed forest of A.mariesii and other plants. Therefore the boundary of A.mariesii forest is sharply defined. Most of the A.mariesii forests distributed in a gentle slope on the summits (about Alt.1300-1360 m). The dominance vegetations are S. kurilensis grasslands, Fagus crenata and Betula ermanii broad leaf forests. The soil profiles in these vegetations resembled each other regarding the existence of humic soil layer before To-Cu tephra layer (6ka:Machida and Arai, 1992). The soil in the A.mariesii forest area had higher moisture content than that in other vegetation area.
As these results, it’s considered that A.mariesii forest is distributed in a gentle slope on the summits and high soil water area. This means Pseudo-Alpine zone is formed by the localized-distribution of A.mariesii forest on high soil water area.