Spatio–temporal distribution of vegetation during the late Holocene at Oninuma, Fukushima Prefecture (northeastern Honshu) was reconstructed from pollen and fossil wood assemblages and by radiocarbon dating. Circa 2500 years ago, Alnus sect. Gymnothyrsus dominated the fan swamp forest in this area, while Quercus grew on the surrounding hills. By ca. 1500 years ago, Fraxinus and Fagus increased on the fan and the hills, respectively. By ca. 800 years ago, an Alnus-dominated swamp forest covered the fan, accompanied by Thujopsis dolabrata and Chamaecyparis pisifera. The distribution of fossil woods showed that T. dolabrata mainly grew in the center of the fan, whereas C. pisifera grew throughout it. The 120–180 tree rings and the horizontal spread of the roots of C. pisifera trees implied that the swamp forest continued for at least 200 years on the peaty land. It is probable that T. dolabrata and C. pisifera were once significant components of the swamp forest in northeastern Honshu similar to Cryptomeria japonica that formed buried forests of the late Holocene in western Honshu. Probably, C. japonica also grew on the mountains around the site.
The Terano-higashi site is one of the most important wetland sites of the late to final Jomon periods in the Kanto plain, central Japan. The total 15 wooden structures excavated from a valley at this site clearly showed the characteristic utilization of lowland, water, timber, and vegetable food resources during these periods. We did an AMS radiocarbon dating of the seven wooden structures and tried a 14C wiggle matching for a timber of a wooden structure, SX-048, to obtain a more refined chronology. According to the radiocarbon dating, these wooden structures were classified into four groups: ca. 4500–4200 cal BP (earliest to early phases of the late Jomon period) of SX-077, 3600–3300 cal BP (late to final phases of the late Jomon period) of SX-074 and SX-046, ca. 3300–2900 cal BP (early to late phases of the final Jomon period) of SX-075, SX-041, and SX-048, and ca. 2900–2700 cal BP (middle phase of the final Jomon period) of SX-043. The wiggle matching indicated that SX-048 was constructed a little after 3100 or 3075 cal BP, coinciding with the Obora BC (Angyo 3b) type phase of the final Jomon period. At the Terano-higashi site, characteritically for these periods, timbers with large diameters were used for large wooden structures such as SX-048, and we could reaffirm that such timber usage characterized the lowland use during the early phase of the final Jomon period in the Kanto plain.
Fruits of Cannabis sativa were found from the sediments of the earliest Jomon period at the Okinoshima site, Tateyama City, Chiba Prefecture, central Japan. The authors conducted AMS 14C dating of the Cannabis sativa fruits themselves. The obtained date was 8955 ± 45 14C BP, and the calibrated date is ca. 10,000 cal BP. Thus the fruits of Cannabis sativa excavated from the Okinoshima site can be certainly placed at the Yoriitomon pottery phase of the earliest Jomon period, which coincides with the early Holocene. It is the oldest record of the fruits of Cannabis sativa in the world at this moment. Hemp may have been cultivated and utilized from the earliest Jomon period.
Morphological characteristics of silica body (opal phytolith) derived from Imperata cylindrica (cogon), Saccharum spontaneum (talahib), and Themeda triandra (samon) were described on a hill in central Luzon, Philippines. Discriminant analysis using silica body morphology indicates that the three species can be identified by morphometries of motor and short cells.