Last 2400 yrs. Environmental changes and human activity recorded in the gyttja-type bottom sediments of the Młynek Lake (Warmia and Masuria Region, northern Poland)

Abstract

Abstract. In the densely forested Warmia and Masuria region (north-eastern Poland) there are many lakes characterized by small size, calm sedimentation and lack of tributaries, which makes them a very good archive of environmental data for the Holocene. For this reason, one of them – the Mlynek Lake, located near the village of Janiki Wielkie, has been selected for multi-faceted palaeoenvironmental research based on a precise radiocarbon scale. Bottom sediments of this reservoir also contain unique information about anthropopression, because a defensive settlement has been operating on its northern shore since the early Iron Age to early Medieval period, which gives opportunity to correlate paleoenvironmental data with phases of the human activity in the last 2400 years. Between 3rd–2nd 2century BC the lake was surrounded by a dense forest with domination of warm and wet climate conditions. In turn of 2nd century BC and 2nd century AD forest around reservoir was much reduced, what can be associatedwith the first – early iron age – occupation phase attested on the strong hold located close to the lake. Between 2nd–9th century AD gradual restoration of forest and decline of human settlements is attested, along with lake deepening and onset of colder and humid climatic phase which correspond to global cooling episode known as Bond 1 (1.5 ka BP). Period between 9th–13th century AD indicates again intensive forest clearing around the lake in result of human activity (Middle Age settlement phase on stronghold). This period is characterized by climate change towards warming, which confirms the gradual 33shallowing of the lake (Middle Age warming period). Since 13 up to 17th century AD intensive cultivation34activity around lake tool place. The landscape is subjected to strong human transformations which means that environmental and climate changes are not so clear. However, changes in lake sedimentation can be seen around 1500, which may be associated with so called Little Ice Age - clod interval.