Determining the responses of vegetation to natural processes and human impacts in north-eastern Poland during the last millennium: combined pollen, geochemical and historical data

Pollen, charcoal and geochemical investigations were carried out on annually laminated sediments of Lake Zabinskie (54 degrees 07'54.5 '' N; 21 degrees 59'01.1 '' E) and the results were combined with historical and climate data to better understand the mechanism behind plant cover transformations. A millennium-long record of environmental history at 6-years time resolution permitted an assessment of vegetation responses to past human impact and climate fluctuations. Our results show that the history of the region with repeated periods of warfare, epidemics, famine and crop failures is well reflected by environmental proxies. Before the Teutonic Order crusade (AD 1230-1283), agricultural activities of the Prussian tribes were conducted at a distance from the studied lake and caused slight disturbances of local forests. A stronger human impact was registered after ca AD 1460. We confirm that co-domination of pine forests with spruce and oakhornbeam forests on drier habitats as well as the presence of birch and alder woods on wet surfaces near the lake lasted until AD 1610. We identified a transition period of 20 years between AD 1590 and 1610, when forest cover was significantly reduced and the area was partly transformed into open land used for farming activities. The comparison of our data with other pollen datasets from the region confirms significant spatio-temporal differences in the initiation of large-scale woodland clearings in the Great Masurian Lake District. A strong increase in local cultivation was noted after AD 1750 and became even stronger in the period AD 1810-1940. The last 60 years experienced a succession from arable fields and open grasslands to more tree-covered habitats overgrown by birch and alder.