Main patterns of present-day zonal vegetation development in Kaliningrad Oblast, Russian Federation (southeastern Baltic), inferred on palynological data

Abstract

This article is devoted to the question of zonal vegetation formation on the territory of Kaliningrad Oblast, Russian Federation, during the Mid- and Late Holocene. Based on palynological data, the main variants of zonal phytocoenoses are defined. It is stated that the formation of present-day zonal vegetation in the region can be derived from the species-rich deciduous forests which became dominant in the study area up to the middle of the Atlantic (7000-6000 cal BP). These plant communities, the key elements of which belong to species of the ‘nemoral complex’ ( Quercus , Ulmus , Tilia , Corylus ), could be considered the climax vegetation corresponding to the mid-Holocene Climatic Optimum. Their further development during the Late Holocene consisted of several structural shifts, such as the invasion of hornbeam ( Carpinus betulus ) during the Sub-Boreal; the invasion of spruce ( Picea abies ) during the Sub-Boreal in the southern part of the region and during the Atlantic and Sub-Boreal in the northern part; the distribution of beech ( Fagus sylvatica ) as a characteristic species of deciduous forests in the southern part of the region during the Atlantic and Sub-Boreal. The lowland habitats, especially in the Neman Delta landscape area, had been occupied by communities of the black alder ( Alnus glutinosa ). These processes led to the formation of three variants of nemoral zonal vegetation on the territory of the region: 1) oak-linden-hornbeam forests, 2) spruce-broadleaved forests with an admixture of hornbeam, 3) black alder communities. All three variants were dominant during the Mid- and Late Holocene (≈ 5000-1300 cal BP). In the later period, a common decline of broadleaved species is recorded with a simultaneous increase of conifers, apparently as a response to climate cooling. Regarding present-day climate conditions, the boundary of Fagus distribution range in the region should be set more northeastwards than currently. Substantial structural alterations occurred in the nemoral forests under anthropogenic impact during the last 300 years, though in the Neman Delta area this transition started later (150-200 years ago) due to difficult access to the area.