Zmiany poziomu płytkich wód gruntowych w głównych siedliskach Puszczy Zielonka

The study demonstrates trends of ground water level changes in main forest habitats in the Zielonka Forest (western Poland) in period 1970−2009. The soils in this area are formed by sands with a low clay content, overlying loose sands with admixture of gravel and slightly sandy clay. Scots pine (Pinus sylvestris L.) is the dominant tree species. The predominant forest site types are: fresh mixed coniferous forest, fresh mixed forest, fresh broadleaved forest and alder swamp forest. The trend in the period of 1970−2009 is not significant at α=0.05 for annual precipitation in the Zielonka Forest, while for average annual temperature it is significant and amounts to about +0.05°C/year. Primary research material were: the ordered results of the measurements of ground water level in Potasze forestry from 1970 to 2009 (14 wells) and the ordered results of the measurements of ground water level throughout the Zielonka Forest from 2001 to 2009 (132 wells). Decreasing time trends of ground water level in the investigated habitats in 40 year period are significant at α=0.05. The greatest annual fluctuations in ground water level were observed in alder/ash swamp forest site types, where shallow ground water level was the highest. Average ground water level in the Zielonka Forest throughout the study period decreased by about 50 cm, but in fresh mixed forest it was 49 cm, in fresh mixed coniferous forest – 57 cm, in fresh broadleaved forest – 87 cm and alder carr – 31 cm. Ground water decrease in the Zielonka Forest can be associated with intensified impact of the climate changes. Variability of the ground water level is mainly determined by the depth of their deposition.