09:30 〜 09:45
[MIS13-09] 八幡平および秋田駒ヶ岳における過去2,500年間のオオシラビソ林分布の時空間変化
キーワード：オオシラビソ林、亜高山帯、時空間変化、八幡平、秋田駒ヶ岳
This study aimed at clarifying the trends of Abies mariesii distribution and the environmental factors that determine moisture conditions in wet meadows, such as landform, and surface geology. Further, it aimed to discuss the factors underlying the difference in distribution of A. mariesii forests between the subalpine (Mt. Hachimantai) and the pseudo-alpine zone (Mt. Akita-Komagatake).
In Mt. Hachimantai, the landform consisted of volcanic original surface (angle: 1-10°), dissected slope (angle: >10°). This area had a high percentage and density of wet meadow distribution. Thick A. mariesii forest tended to be distributed around wet meadows on volcanic original surface. Surface geology survey revealed that loam layers composed of clay were present in all the sites. A. mariesii forest area in the southern part was narrower than that in the northern part. According to pollen analysis, Abies pollen started to occur approximately 2,500 years ago in the northern part and landslide area, and approximately 1,000 years ago in the southern part (Morita, 1985).
In Mt. Akita-Komagatake, the landform was similar to that of Mt. Hachimantai. Wet meadow distribution in the northern part was similar to that in Mt. Hachimantai in terms of density of wet meadow distribution. In the southern part, the percentage of wet meadows was extremely low. The thickest A. mariesii forest in either part of Mt. Akita-Komagatake was narrower than that in Mt. Hachimantai. Scoria and pumice composed of granule gravel characterized the surface geology of the southern part. According to pollen analysis, Abies pollen started to occur approximately 1,000 years ago in the northern part, and approximately 2,500 years ago in southern part (Morita, 1985; Ikeda, 2002).
Evidently, it can be concluded that the present distribution of A. mariesii forest has been determined by the starting time and the speed of expansion of A. mariesii forests, which are affected by environmental conditions such as wet meadows.
In Mt. Hachimantai, the landform consisted of volcanic original surface (angle: 1-10°), dissected slope (angle: >10°). This area had a high percentage and density of wet meadow distribution. Thick A. mariesii forest tended to be distributed around wet meadows on volcanic original surface. Surface geology survey revealed that loam layers composed of clay were present in all the sites. A. mariesii forest area in the southern part was narrower than that in the northern part. According to pollen analysis, Abies pollen started to occur approximately 2,500 years ago in the northern part and landslide area, and approximately 1,000 years ago in the southern part (Morita, 1985).
In Mt. Akita-Komagatake, the landform was similar to that of Mt. Hachimantai. Wet meadow distribution in the northern part was similar to that in Mt. Hachimantai in terms of density of wet meadow distribution. In the southern part, the percentage of wet meadows was extremely low. The thickest A. mariesii forest in either part of Mt. Akita-Komagatake was narrower than that in Mt. Hachimantai. Scoria and pumice composed of granule gravel characterized the surface geology of the southern part. According to pollen analysis, Abies pollen started to occur approximately 1,000 years ago in the northern part, and approximately 2,500 years ago in southern part (Morita, 1985; Ikeda, 2002).
Evidently, it can be concluded that the present distribution of A. mariesii forest has been determined by the starting time and the speed of expansion of A. mariesii forests, which are affected by environmental conditions such as wet meadows.