Vegetation history during the last 17,000 years around Sonenuma Swamp in the eastern shore area of Lake Biwa, western Japan: With special reference to changes in species composition of Quercus subgenus Lepidobalanus trees based on SEM pollen morphology

A pollen record of Sonenuma Swamp provides vegetation history for the last 17,000 years around the eastern shore area of Lake Biwa, western Japan. Identification of Quercus subgenus Lepidobalanus pollen by using scanning electron microscope shows composition changes of deciduous oaks at the species level. During 17,000 to 15,000 cal BP, deciduous broadleaved forest mainly consisted of Q. sect. Prinus developed around Sonenuma Swamp associated with pinaceous conifers and birch trees. Q. sect. Prinus and Q. dentata became dominant in the forests from 15,000 to 10,000 cal BP. The increase of Q. dentata in this period was possibly related to fire events around Sonenuma Swamp, as indicated by the charcoal record. From 10,000 to 6000 cal BP, Celtis/Aphananthe trees became dominant in forests around Sonenuma Swamp. Temperate evergreen broadleaved forest composed of Q. subgenus Cyclobalanopsis trees along with Q. sect. Cerris trees developed during the period 6000 to 2500 cal BP. After 2500 cal BP, pine forests and grassland increased, with charcoal abundance likely affected by human activity around Sonenuma Swamp.