著者
宮地 直道 能城 修一 南木 睦彦
出版者
日本第四紀学会
雑誌
第四紀研究 (ISSN:04182642)
巻号頁・発行日
vol.23, no.4, pp.245-262, 1985-01-31 (Released:2009-08-21)
参考文献数
14
被引用文献数
2

The eastern and southeastern slopes of Fuji Volcano which are covered with Fuji 1707 Tephra lack subalpine coniferous forests. At three sites on the southeastern slope, geological and paleobotanical studies were made on the fossil forests buried under this tephra. This pyroclastic fall deposit ejected from the Hoei Craters of December 16, 1707 A.D. consists of a lower pumice bed (Ho-Ia) and upper scoria beds (Ho-Ib) in this area. The wood fossils and other plant macrofossils are buried in or beneath the Ho-Ia, which consists of many bombs and coarse pumice fragments, with a maximum thickness of 70cm. The occurrence of wood fossils and other plant macrofossils indicate that leaves, branches and stems were buried in that order in the lower pumice bed very rapidly. Most of the wood fossils were carbonized by the heat of the pumice fragments.The forests which existed until December 16, 1707 A.D. were reconstructed. At site MK-4 (1745-1785m in alt.), there were stands composed of subalpine conifers such as Abies veitchii, Tsuga diversifolia and Picea jezoensis, one stand of Larix and one small stand of deciduous broad-leaved trees, that were distributed in patches. At site MK-2 (1680m in alt.), there was a forest of Abies, Tsuga diversifolia, and Picea jezoensis with a few broadleaved trees. At site MK-5 (1630m in alt.), there was a forest of Abies, Picea jezoensis, and Picea cf. maximowiczii with a few montane-zone elements such as Pterocarya or Pourthiaea.These facts indicate that, prior to the eruption, subalpine coniferous forests and montane ones existed on the southeastern slope of Fuji Volcano, and that the boundary between the subalpine zone and the montane zone was at about 1650m in alt. around the three sites. The elevation of this boundary is lower than that of the present one on the southern slope of Fuji Volcano. Since then, the forests have been replaced by a Larix forest or a Quercus and Betula forest at sites MK-2 and MK-5 where the surfaces have become relatively stable; whereas, a volcanic desert still exists around site MK-4 situated in the course of an avalanche chute.
著者
辻 誠一郎 南木 睦彦 大沢 進
出版者
Japan Association for Quaternary Research
雑誌
第四紀研究 (ISSN:04182642)
巻号頁・発行日
vol.22, no.4, pp.279-296, 1984
被引用文献数
5 13

相模地域の後期更新世の大型植物化石・花粉化石群集を記載し, 植物群と植生, および古環境を論じた.<br>植物分類・地理学上注目すべきイワヒバ・カラマツ・トウヒ各属の大型植物化石の形態を記載した. このうちトウヒ属は, トウヒ, ヒメバラモミの2種とトウヒ属A・B・Cの3型に分けられた.<br>主に, スギおよびヒメバラモミからなる冷温帯針葉樹林が約9万-6万年前に優勢であった. これは上部冷温帯の年降水量の多い湿潤な気候を示す. 約6万-5.5万年前の三崎海進を通じての植生は, 冷温帯のナラ類林の拡大によって区別される. これは年降水量の少ない比較的温暖な気候を示す. 約5.5万-5万年前の主にヒメバラモミとカラマツ属からなる亜寒帯ないし冷温帯針葉樹林は, 関東地方で従来知るかぎり後期更新世における最初の寒冷気候を示す. この時代は立山で確認された室堂氷期にあたる. 亜寒帯針葉樹林と冷温帯落葉広葉樹林の間の移行的な混交林が約1.6万-1.3万年前に優勢であった. このような森林は更新世末期の南関東に分布拡大していたと思われる. この時代の富士山東麓における亜寒帯針葉樹林の下降は1,000m以上であった.<br>(地名)<br>Eda 荏田<br>Ekoda, Egota 江古田<br>Iseyamabe 伊勢山辺<br>Kyuden 給田<br>Nippa 新羽<br>Rengeji 蓮花寺<br>Shijuhasse River 四十八瀬川<br>(地層名)<br>Kissawa L. 吉沢ローム層<br>Younger L. 新期ローム層<br>Anjin Pumice 安針軽石