Environmental changes in SE Estonia during the last 700 years

Sediment sequences retrieved from three lakes in southeastern Estonia were analysed for lithology, pollen stratigraphy and high-resolution loss-on-ignition (LOI) to study the environmental changes during the last 700 years.Age control was provided by varve counts, AMS 14 C and 210 Pb dates complemented by 137 Cs and 241 Am measurements, which confirmed the annual character of the sediments.LOI results displayed several periods with reduced values of organic matter and increased mineral matter fluxes.Organic production in the lakes and on the catchment was sensitive to climate change and human impact, while mineral load was mostly determined by external factors, which promoted soil erosion and influx into the lake.During the last 700 years in the environmental history of SE Estonia the three main phases were distinguished: low land-use phase between AD 1300 and 1750, extensive arable farming phase at AD 1750 and 1940 and diminished arable farming phase since AD 1940.This study showed, that the formation and development of the landscape in SE Estonia during the last 700 years was characterized by rapid changes in vegetation and lake sediment composition determined mostly by human impact, certain historic processes and climate change.