Reconstructing the Holocene environments in the Russian sector of the Neman Delta area, Kaliningrad Region

A history of landscape development in the Russian part of the Neman Delta area during the Holocene, with an emphasis on the formation of forests and wetlands, is deduced based on pollen analysis, radiocarbon dating, a field topography survey, and macrofossil analysis of peat deposits in a coastal mire, the Koz’ye Bog. Several 1,000–2,000-year time lags in vegetational development were revealed here, though they have not been recorded for other landscapes in the Kaliningrad Region and the adjacent areas in the southeastern Baltic. The causes are still not completely clear, but they presumably related to some of the regional patterns of climate development and the submergence of the area during the second Littorina transgression (7,500–7,000 cal. yr BP). It is established that cryophilic open tundra-like vegetation existed here not only in Late Glacial time (Younger Dryas) but up to the mid-Boreal (9,700–9,500 cal. yr BP). A transition from the open landscapes of the Late Glacial to birch and then pine forests occurred here 9,700–8,700 cal. yr BP, whereas the expansion of thermophilic broadleaf species of the nemoral (temperate) association (Quercus, Ulmus, Tilia, Corylus) was recorded only in the period 6,400–3,500 cal. yr BP. Peak expansion of Alnus occurred here only in the late Subboreal (3,500–2,700 cal. yr BP), while in adjacent areas it reached its maximum as early as the Atlantic. The general vegetation dynamics in this area during the Late Glacial and the Holocene could be referred to as a transition from the dominance of pine forests to a wide dispersal of alder carrs. This environmental shift was caused not only by climatic factors but probably also due to the transformation of the hilly coastal terrace into a low-lying plain landscape after flooding during the transgressions of the Baltic.