Reconstruction of a coastal raised bog development in the proximal part of the Curonian Spit, Kaliningrad Region, Russia, South-Eastern Baltic

摘要

The Holocene development of a peculiar coastal peatland (raised bog Svinoye), southern Curonian Spit, Russia, is reconstructed based on the analysis of taxonomic diversity of plant macrofossils and radiocarbon dating of peat and gyttja deposits. The development of the bog can be referred to the primary mire formation, which was preceded by a period of gyttja accumulation (7500-7000 cal. yr BP) in a shallow water body. The mire vegetation development started from 7000 cal. yr BP through the spread of the alder carrs and reed stretches that presumably experienced inundation during transgression events of the forming Baltic over the period 7000-6300 cal. yr BP). These habitats were successively replaced by the communities of the rich fen, transition mire and active raised bog. During the whole post-transgression period (6300 cal. yr BP - present time), the vegetation successions were not influenced by the sea-level oscillations but were determined by climatic and anthropogenic factors. The diagrams of the botanical composition of peat enabled to assign and describe 12 formation phases for the Svinoye bog ecosystem. In contrast to the other peatlands in the region, the stage of transition mire persisted here over a long-term period of 1200 years. The formation of a typical raised bog began around 3400 cal. yr BP. As recent as 200 years ago, the ecosystem had the characteristics of a maritime climate mire. The mean peat accumulation rate was defined for the period of the last 7000 year as having the highest values in the Late Atlantic and the Late Sub-Atlantic (1.7-2 mm/yr), while the lowest increment (0.8 mm/yr) is recorded for the whole Sub-Boreal.