Warm temperate mixed forests consisting of conifers (Pinus, Abies, Tsuga, and Pseudotsuga) and deciduous broad-leaved trees (Carpinus, Zelkova, Fagus, and Quercus subgen. Lepidobalanus) were reconstructed from fossil pollen and plant macrofossil assemblages in Middle Pleistocene deposits at Ohnodai (134°00´E, 33°26´N, Alt. 40–50m), Muroto-misaki Peninsula, Kochi Prefecture. The sediments including the fossil assemblages were identified as marine sediment, because they contained sulphur and fossil fruits of a seaside plant (Vitex rotundifolia L.f.), and were correlated with the Ma5 Marine Clay Layer in the Osaka Group based on topographic and paleomagnetic investigations. At the time of deposition of the fossil assemblages, evergreen broad-leaved trees such as Castanopsis and Quercus subgen. Cyclobalanopsis scarcely flourished in this area, while lucidophyllous forests were widely distributed during the Holocene in this same area. The difference in vegetation between the two interglacial periods suggests difference in climatic conditions, especially winter temperature defining the development of evergreen broad-leaved forests.
View full abstract