Vegetation response in the surrounding area of Zarya Bay (the Sea of Japan) to multidecadal climatic variations over the past 5500 years

The development of vegetation on the eastern coast of Primorye in the low and middle mountains of the eastern macro-slope of Sikhote-Alin over the past 5500 years was reconstructed based on the pollen analysis of lacustrine and bog sediments. The temporal resolution of the reconstructions is 30–88 years. Twenty phases of vegetation development, lasting from 670 to 120 years, were identified, amidst which the multidecadal variations took place. The transport of pollen and spores played a certain role in the variability of pollen spectra. Short-term hydroclimatic changes are reflected in the structure of the pollen spectra as changes in the ratio of broadleaf to dark coniferous pollen, the peaks of which are consistent with solar activity variations. A long phase of stable development of Korean pine-broadleaf forests was noted at the end of the Middle Holocene (5050–4380 yr BP). Vegetation changes were recorded during the 4.2 ka event, characterized by cool climatic conditions and low humidity. Korean pine generally expanded in cooler and more humid conditions, and its presence declined during the periods of low humidity. The biggest distribution of Korean pine forests was recorded during 2820–2640 yr BP cooling. Dark coniferous forests became widespread at the beginning of the Little Ice Age. The role of birch trees increased in the late Holocene and modern conditions. Alder thickets spread along the swampy shores of the lake during decreased humidity. Slopewash, which intensified during the periods of high typhoon frequency, played a significant role in spore transport. Allochthonous pollen (Cryptomeria, Fagus) transported in bioaerosols from remote areas, possibly from the Japanese Islands, was found. Ephedra pollen might have been carried by dust storms from the continental interiors. Signals of anthropogenic influence on the landscape have been noted since the Bronze Age. The most significant human impact to forests occurred in the late 19th and early 20th centuries, before the establishment of a nature reserve.