Fine-resolution pollen-based evidences of farming and forest development, south-eastern Estonia

The pollen stratigraphical and lithological data obtained from Lake Lasva, southern Estonia, are summarized. The land-use and vegetation history during the last 6300 years in an agricultural area with dense prehistoric setting is discussed. A high sedimentation rate and laminated structure of lake deposits enabled high-resolution palaeobotanical study of a 985 cm long core. Accelerator mass spectrometry 14C dates show good linearity and fit wed with varve counts. Up to ca 2900 years BP, birch, pine, spruce and broad-leaved species, later mostly birch, pine and alder, grew in that area. The first weak signs of human impact were traced at 6300 years BP. Human activities were more pronounced between 5400-5100 and 3800-3500 years ago, due to the foundation of Neolithic settlements not far from the lake. The first attempt of small-scale tillage, detected from the first finds of Triticum pollen, followed by a long-term gap, dates back to 5100 years BP. Crop cultivation (Cannabis, Hordeum, Triticum and Secale) became the main means of subsistence not until the Iron Age at about 1600-1400 years ago, but extensive arable farming started to develop 800 years ago, after the German crusaders invaded the area. Pollen diagrams display several setbacks in arable farming, mostly caused by crop fadure due to climate deterioration and decrease in the population caused by famines, wars and epidemics.