Evolution of vegetation in the Utinoe Lake basin (the Russian Far East) during the Middle-Late Holocene

Abstract

Evolution of vegetation in the Utinoe Lake basin was studied. Periodicity of vegetation changes in its basin were reconstructed by the palynological data. The Middle Holocene stage of the vegetation evolution proceeded in the conditions of general planetary increase in average annual temperatures, accompanied by flooding of lowland plains by the Sea of Japan. Composition of the polydominant forests on the ridges during the Middle-Late Holocene was more rich what the present time were formed. Vegetation of the foothill plains was represented with sedge and mixed meadows. The Late Holocene stage was characterized by a decrease in average annual temperatures and series of climatic changes. Its beginning was marked by the cooling, during which the coastal lowlands were freed from sea waters. Climate deterioration caused expansion of dark coniferous and small-leaved plants in the Utinoe Lake basin, as well as reduction of polydominant forests. On the foothills near the coast of the Peter the Great Bay sedge meadows were developed, sometimes there were thickets of Betula sect. Nanae and sphagnum swamps. At the end of the Late Holocene the warming occurred again. On the mountain frame of the Utinoe Lake basin, the vegetation formations with the dominance Q. mongolica, Q. dentata, A. holophylla, P. koraiensis with the presence of birches began to dominate. The dissemination of Pinus densiflora, Ulmus, Carpinus cordata and Acer  has increased. On the lowlands the sedge-reed meadows with different grass dominated.