Sub-fossil wood from the Rucianka raised bog (NE Poland) as an indicator of climatic changes in the first millennium BC

The dendrochronological studies were carried out on very well preserved sub-fossil pine wood found in the biogenic deposits of the Rucianka raised bog (NE Poland). Local floating chronol-ogies, covering the period 990-460 cal BC, were dated on the basis of radiocarbon analyses. Growth depressions in annual tree-ring widths indicated periodical deterioration of the environmental condi-tions, which affected tree growth. Identified germination and dying-off phases (GDO) should be re-lated to the wetter climatic periods. The extinction of trees took place during periods of higher groundwater level which, in turn, caused favourable conditions for growth of young pines.