Paleoenvironments of Kuril Islands in Late Pleistocene–Holocene: Climatic changes and volcanic eruption effects

Abstract

The Kuril Islands are noted for a variety of landscapes, from nemoral broadleaf forests to forest-tundra and tundra. Some large islands display a distinct altitudinal zonality. Environments of the islands bear evidence of various catastrophic events that controlled the landscape evolution to a considerable extent. Changes of climate during the Pleistocene were of particular importance in evolution of the environments. Dramatic rapid fluctuations of climate at the Late Pleistocene–Holocene boundary resulted in repeated restructuring of landscapes at the land bridge connecting the South Kuriles and Hokkaido. In the southern part of the Small Kuril Ridge open forests might persist until the land mass was broken into small islands dominated by meadow–marsh vegetation since the Middle Holocene. On the Central and Northern Kuril Islands, environmental changes during the Middle and Late Holocene resulted both from climatic fluctuations and from repeated fallout of volcanic ash. Deposition of organic matter began about 6.5 ka BP. It resulted from the onset of more favorable conditions, namely warming, increase of moisture supply and reduction of volcanic activity. The evolution of island landscapes consisted mainly in changes of relative area occupied by various plant communities, most of which are present in modern vegetation. The Holocene climatic optimum was not particularly pronounced in this part of the Great Kuril Ridge. Some consideration is given to issues of changes in zonal boundaries at different time intervals within Late Pleistocene and Holocene.