Transformation of Lake Ecosystem into Peat Bog and Vegetation History Based on Durne Bagno Mire (Lublin Polesie, E Poland)

Abstract

Transformation of Lake Ecosystem into Peat Bog and Vegetation History Based on Durne Bagno Mire (Lublin Polesie, E Poland) In this paper, the history of Durne Bagno, i.e. the largest peat bog in the Lublin Polesie, is shown. Peat bogs are a unique element of the Polesie landscape. They occur mostly in the subregion of the Łęczna-Włodawa Lake District occupying 1.07% of its area. They fill basin-shaped depressions without outflow, often in the immediate vicinity of dystrophic lakes. Based on interdisciplinary research, the changes of vegetation cover and the Durne Bagno lake-mire ecosystem in the Late Glacial and Holocene are presented. The environmental conditions are reconstructed from pollen analysis, detailed identification of algae of Pediastrum genus and chemical composition of deposits, together with the results of Cladocera analysis. The distribution of archaeological artefacts in the surroundings of Durne Bagno peat bog gives the view on the intensity of settlement in this area. The duration of the limnic and mire stages during the development of the ecosystem was different in different parts of the examined depression. In its central part the limnic stage lasted about 8000 years and included the period from the Late Glacial to the middle Holocene (to about 6000 BP). It is represented by 7 pollen zones and 6 chemical zones. The mire stage contained a part the Atlantic period and on the Subboreal and Subatlantic periods. It is represented by 4 pollen zones and 5 chemical zones. Limnic and mire deposits differ widely in the concentrations of chemical elements. The contents of mineral material and almost all analyzed elements in limnic deposits are high. These deposits are characterized by positive correlation between the contents of Zn and Cr and the frequency of Cladocera fauna. Peat contains very low amount of mineral material. The contents of Ca, Sr and Ba are rather high in sedgemoss peat. The concentrations of these elements decrease upwards due to oligotrophic processes and sedentation of sedge-Eriophorum-Sphagnum peat. Peat succession was modified by pastoral economy of prehistoric man.