EVIDENCE OF LGM AND HOLOCENE OPTIMUM FROM THE PISTON CORE (ST-21) OBTAINED IN THE EAST SEA, KOREA

Pollen analysis in ST-21 piston core drilled from the ocean floor adjacent Dokdo, East Sea, Korea, reveals paleoenvironmental changes during the Late Quaternary. Paleotemperature and vegetation density were elucidated by conifer pollen percentage and total pollen concentration. Moisture change inferred from aridity index (pollen ratio of Artemisia, Chenopodiaceae, and Cyperaceae) and ratio of NAP (Non Arboreal Pollen) and NPP (Non Pollen Palynomorphs). The whole core is divided into five local pollen zones based on pollen assemblage. Ages of local pollen zone boundaries were estimated using extrapolation based on two radiocarbon dates (ca. 11,400 cal BP at 42cm and ca. 39,300 cal BP at 157cm). Each local pollen zone coincides with MIS stage (1~5). It suggests that local pollen zone is well reflected global climate change. The paleoclimate of Dokdo, during the period of last 100,000 years, was experienced fluctuation of warm and cold periods: three warm (local pollen zone I, III, and V) and two cool periods (local pollen zone II and IV). Humidity around the Dokdo area also changed showing an increase trend from bottom to top. Particularly, a fugal genus Glomus (type 207) which is chlamydospore of endomycorrhizal fungi increased dramatically at local pollen zone I and III. It indicates that terrestrial soil input was intense caused by high rainfall during MIS 1 and MIS 3. LGM (Last Glacial Maximum) in MIS 2 is detected by sharp increase and maximum abundance of conifer concentration together with dramatic decrease and minimum pollen concentration. On the other hand, Holocene Optimum in MIS 1 is also identified by pollen signal.