中部日本とその周辺の鮮新•更新世の地形発達が植物相と植生の変遷に与えた影響について総説した.下部更新統菖蒲谷層ではメタセコイアが氷期の化石群にも含まれていることから.メタセコィァの日本からの絶滅要因として気候よりむしろ生育場所の地形の変化が考えられた.近畿地方中部では植物の絶滅と冷温帯の植物群の出現の時期が.堆積盆地周辺の古地形の変化と良く対応していた.これらのことを検証するために.堆積盆地周辺の古地形に対応した植物の分布を.植物化石群の形成過程を考慮して復元した.日本からの植物の絶滅は.山地形成によって間氷期の植物の分布拡大が妨げられたことで，植物の分布域が西南日本へと縮小していつた結果生じたと考えられる.植物の分布は.乾燥気候が卓越した最終氷期最寒冷期には，気温条件だけではなく土壌水分条件にも制限された.乾燥した立地を中心に亜高山帯針葉樹が冷温帯に分布を拡大した一方で.温帯落葉広葉樹の分布は谷の中の中湿立地に限定された.%This paper reviews the influence of Plio-Pleistocene geomorphological development on floral and vegetation changes in and around central Japan. Because Metasequoia was included in fossil assemblages in the glacial stage in the lower Pleistocene Shobudani Formation, the cause of its extinction from Japan was ascribed to geomorphological changes in its habitat. Plant extinction and the appearance of cool temperate plants in the central Kinki District converged on a period of geomorphological changes in and around sedimentary basins with climate cooling. To clarify the cause of plant extinction, the relationship between plant distributions and paleotopography around the sedimentary basin was analyzed based on the taphonomy of plant fossil assemblages. In consequence of the upheaval of the mountains, some plants were obstructed in their regional expansion during interglacial stages and confined to southwestern Japan, and they finally became extinct from Japan. The dry climate prevailing during the last glacial maximum promoted expansion of subalpine conifers on dry habitats in cool temperate zones and confined distribution of temperate deciduous broadleaf trees in mesic places within valleys.
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