Late Holocene changes in vegetation of the Mrągowo Lakeland (NE Poland) as registered in the pollen record from Lake Salęt

Pollen analysis of sediments from the upper part of bottom deposits from Lake Salęt allowed reconstruction of main stages of the Late Holocene vegetation transformation in the Mrągowo Lake District (from ca. 3600 cal. years BC) and to correlate some of these changes with immigration and economic activity of local human groups. Significant spreading of secondary semi-natural birch forest, development of hornbeam forest and increasing importance of anthropogenic open communities were the most characteristic features of vegetation evolution. A definite breakdown of elm took place between 2900 and 2500 cal. years BC, slightly after increased contribution of birch in woodlands. Disappearance of hazel around 1200 cal. years BC, accompanied by expansion of hornbeam has been observed and should be linked with activity of the Ząbie-Szestno type culture and the Lusatian culture tribes during the Bronze Age, but not with a climate change. Considerable intensification of settlement processes recorded in the younger part of the Subatlantic chronozone was one of the important reasons that were responsible for quick changes in forest structure. Strong and continued deforestation started as early as the end of the 10th century AD and was substantially intensified in the first half of the 13th century.