A 30,000-year Phytolith Record of a Tephra Sequence at the Southwestern Foot of Aso Volcano, Japan

Abstract

 A 30,000-yr record of vegetation history has been constructed using a phytolith analysis of a tephra sequence located at the Kawahara No.3 archaeological site, southwestern foot of Aso Volcano, central Kyushu, southwestern Japan. The sequence was divided into three zones: Zone 3 (>ca. 31 cal ka), Zone 2 (31-13.5 cal ka), and Zone 1 (13.5-0 cal ka) in ascending order. Gramineae phytoliths were predominately detected at most horizons, whereas a small amount of arboreal phytolith was observed mainly at Late Holocene horizons. Zone 3 was dominated by a phytolith of Sasa (mainly Sasa sect. Crassinodi), a cool-temperature dwarf bamboo. However, vegetation composed mainly of Sasa dwarf bamboo had declined slightly in Zone 2, which corresponds to the Last Glacial Maximum. During the Holocene (Zone 1) the Sasa grassland dominated consistently, but phytolith of Pleioblastus (a warm temperature dwarf bamboo) and arboreal such as Distylium increased from 7,300 years ago.