Palynological implication of Holocene vegetation and environment in Pyeongtaek wetland, Korea

Vegetational and depositional environmental changes were interpreted from a trench in ca. 10 000 cal BP sediments in the Pyeongtaek wetland, Korea, based on palynomorph and grain size analysis. From ca. 10 400−8000 cal BP, cool, dry, temperate conditions encouraged Quercus-dominated deciduous broadleaved forest, with conifers and cool-tolerant birch prevailing on hills and in mountainous areas as postglacial warming began. Halophytic Chenopodiaceae pollen and marine dinoflagellates indicate the depositional environment was an intertidal flat. Conditions became warm and wet between ca. 8000 and ca. 6000 cal BP: areas still contained Quercus-dominated deciduous broadleaved forest but with decreased conifers and cool-tolerant birch. The absence of marine dinoflagellates and abundant meso- to hypersaline salt marshes of Gramineae, with a later increase of mesosaline Cyperaceae marshes, indicate a transition from intertidal flat to freshwater swamp. From ca. 6000 to ca. 4500 cal BP, Quercus-dominated forests were replaced by mixed conifer-deciduous broadleaved forests under climatic deterioration. Aquatic genera and freshwater algae indicate that the study area completely changed to freshwater swamp. The directional sequence in relative abundance of taxa (maximum percentage of pollen of Chenopodiaceae followed by Gramineae, Cyperaceae, and aquatics) suggests a gradational pattern indicative of marked environmental clines typical of intertidal habitats.