Variability of groundwater table, atmospheric precipitation and temperature in swamp habitats of the Zielonka Forest Landscape Park

摘要

Results of a study carried out in the Zielonka Forest Landscape Park (central Wielkopolska, middle part of the Warta River catchment) are presented in this paper. The park includes part of a large (15 thousand ha) forest complex called Zielonka Forest. The name pertains to relatively large and dense forest area with small agricultural enclaves situated c. 8 km north-east of Pozna??. Park's landscape of the young glacial type, Pleistocene and Holocene formations, was formed as a result of the Pozna?? stage of the Baltic glaciation. Dominating habitat types in the park are: fresh mixed deciduous forest (58%), fresh mixed coniferous forest (25%), fresh broadleaved forest (10%), alder and ash-alder swamp forests (4%).Analysis of thermal conditions and precipitations was performed for the years 2002-2007 and compared with long-term data from 1987-2007. Annual mean air temperature in the hydrologic year 2003 was lower by 10% than the long-term mean while in the years 2007, 2006 and 2002 it was higher by 29, 9 and 8%, respectively. Low air temperature in the year 2003 was the effect of cold winter. In the summer half-year the temperature was definitely above the mean. Hydrologic year 2003 was the coldest but also the driest (64% of the long-term mean) year in the study period. Variability of ground water tables in swamp habitats was measured in the hydrologic years 2002-2007. During this period the ground water table depth varied from 38 to 181 cm below ground. Mean lowest stages (116 cm below ground) were noted in the hydrologic year 2006 (with the minimum level of 52 cm and maximum 178 cm below ground). The lowest ground water table (181 cm below ground) was, however, noted in 2003 in an experimental plot of the division 85f. The year 2003 was also characteristic for the largest annual amplitude of ground water depths. Obtained results confirm the decisive effect of air temperatures and sums of atmospheric precipitation on ground water table depth in forest swamp habitats. Surprisingly, there was no expected difference in the ground water depth between hydrologic years of extremely different atmospheric precipitations. Smaller variability of ground water level with increasing depth known from the literature was not confirmed either.