大形植物化石からみた中期更新世における北陸地方の植生垂直分布

• Main Authors: 小島 覚, Kojima Satoru
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 植物地理・分類学会 = The Society for the Study of Phytogeography and Taxonomy 2008
• Subjects: Hokuriku Region; Middle Pleistocene; paleo-environment; plant macrofossils; vegetation reconstruction; Tundra
• Online Access: http://hdl.handle.net/2297/00053377; https://kanazawa-u.repo.nii.ac.jp/?action=repository_uri&item_id=47050; https://kanazawa-u.repo.nii.ac.jp/?action=repository_action_common_download&item_id=47050&item_no=1&attribute_id=26&file_no=1

Based on the plant macrofossils discovered in the Kureha Hills, Toyama, Japan, a possible altitudinal vegetationsequence of Hokuriku Region during the Middle Pleistocene Period was reconstructed. Out of the fossilplants discovered and identified, five coniferous tree species were selected. They were Abies homolepis, A. veitchii, Picea jezoensis var. hondoensis, Pinus koraiensis, P. parviflora var. pentaphylla and Tsuga diversifolia. Based on the ecological amplitudes of the extant respective species against the Kira’s warmth index（Wi）, the climatic conditions of the Middle Pleistocene Period were inferred. Then mean annual temperature of the region during the Period was determined to be ca. 10.3℃ lower than the present days. This suggested that altitudinal belts of vegetation of the region were approximately 1,800 m lower than those of the present days. The implication of this would be that both evergreen broad-leaved forest belt and deciduous forest belt did not exist in the region at the time and coniferous forests started immediately from the sea coast extending up to ca. 500 m asl. Above the coniferous forest belt, a scrubby forest belt of Pinus pumila would have developed up to ca. 1,000 m asl., and further up an extensive alpine tundra vegetation would have occurred to the tops of the mountain ranges.