Vegetation history from pollen assemblage since the early Holocene at Manjojiki Mire, southern Hokkaido, northern Japan

Abstract

We reconstructed vegetation changes from a well-dated pollen record since the early Holocene at Manjojiki Mire (660 m a. s. l.) in southern Hokkaido to understand the vegetation history on Kameda Peninsula. The pollen record at the mire indicated that, 1) in ca. 10.0 ka cal BP, a mixed forest of Betula ermanii and boreal conifers surrounded the mire in a cool climate, 2) in ca. 9.5–6.8 ka cal BP, a Betula ermanii dominant forest expanded in a warm climate, 3) in ca. 6.8–1.1 ka cal BP, a Quercus crispula dominant forest developed, and 4) after ca. 1.1 ka cal BP, a Fagus crenata forest flourished around the mire. Additionally, our spatio-temporal comparison of pollen records on Kameda Peninsula showed that boreal coniferous forests consisting mainly of Picea and Abies existed during ca. 15.0–12.0 ka cal BP, that mixed forests of Betula and Quercus developed during ca. 12.0–3.0 ka cal BP, and that Fagus crenata forests flourished after ca. 3.0–1.0 ka cal BP. The results implied that the colonization by Fagus crenata of the peninsula began in ca. 6.0–5.5 ka cal BP, possibly enabled by the sedimentation of tephra from Mt. Komagatake volcano.