Abstract
Buried forests discovered from three sediment layers in the Tachiya River, Yamagata Prefecture, northeastern Japan, date to the Last Glacial Maximum (LGM) and the immediate post-LGM period according to radiocarbon dating. This study identified the fossil woods anatomically and examined the sediments for plant macrofossils and fossil pollen. Between ca. 22,000 and 18,000 cal BP, the study site’s wetland forests were dominated by Picea sect. Picea, including P. maximowiczii and P. tomizawaensis. Other accompanying tree species included Abies sachalinensis and Larix gmelinii, with Carex middendorffii on the forest floor. Picea spp. comprised 84% of the 108 buried trees dated to ca. 22,000 cal BP. These Picea trees often had stem diameters exceeding 40 cm and reaching up to 64 cm with over 260 growth rings. The buried forest also contained Larix and Abies trees less than 40 and 20 cm in stem diameter, respectively. On the surrounding slopes, conifers belonging to Pinus subgenus Haploxylon and Tsuga spp. were distributed. The presence of Larix gmelinii cones and Abies sachalinensis cone scales in the sediment suggested their southernmost distribution extended to the Yamagata Basin of Yamagata Prefecture during the LGM.
