This thesis will demonstrate the necessity of viewing the reconstruction of Iwajyuku Age vegetation from two standpoints. First, reconstruction studies have tended to emphasize arbors which form the forest canopy, in spite of the presence of many other miscellaneous tree and herb species. In prehistory, however, these species were not only component of the environment but they were also potential resources for people inhabiting the forests. Therefore, reconstructions of plant communities should include all species, their distribution and potential uses in order to have a better understanding of the people's lives. Second, the density of the underbrush in forests and the distribution of forest and open space must be investigated because these factors must have affected the way people hunted and where they settled.
Fossil wood and plant macrofossil assemblages of the Late-Latest Jamon Period discovered at the Inashi-yashiki-ato Site, Saitama Prefecture, were studied and compared. In the fossil wood assemblages obtained from two blocks, Quercus sect. Aegilops dominated with more than 50% of the assemblage. Castanea crenata was also present. In the plant macrofossil assemblages obtained from three blocks, Quercus including Q. serrata and Q. cf. acutissima dominated among the arbors. Wisteria was also found in two blocks. Trapa including T. incisa dominated among the herbs. Scirpus fluviatilis and Polygonum maackianum were also present in one block. Thus, deciduous forests consisting of Quercus subgen. Lepidobalanus and Castanea crenata covered the surrounding uplands during the LateLatest Jomon Period, and Trapa covered the pond surfaces in the lowlands. Dominance of Q. sect. Aegilops has not previously been detected in the Kanto Plain, and may have charaterized the vegetation in the middle of the Oomiya Upland.
Four palaeoenvionmental stages were identified based on pollen stratigraphy and lithology of the Late Pleistocene N ogawa Peat at Chofu, Tokyo. Stage 1 is characterized by a standing of temperate deciduous broad-leaved forest composed of mainly Alnus and Quercus subgen. Lepidobalanus. Stage 2 is distinguished by a decreasing of temperate deciduous broad-leaved forest elements, and the beginning of an expansion of Pinus subgen. Haploxylon. Stage 3 is defined as a dominance of such conifers as Pinus subgen. Haploxylon and Abies with fern community in the valley. Stage 4 is distinguished by a decreasing of conifers and an invasion of Alnus and other temperate deciduous broad-leaved trees. An expansion of conifers in Stage 2 and Stage 3 shows a cooler climate than that in Stage 1 and Stage 4. From the correlation with stratigraphy and chronology in the Kanto plain, Stage 2 and Stage 3 were dated to be 22,000~21,000 and 21,000~ 18,000 years ago.