Summary:

The paper covers research on groundwater level depth dynamics in unevenaged forest stands of swamp habitats as influenced by meteorological conditions (air temperature and rainfall). The research period comprised hydrological years 2002–2005 with 7 experimental plots examined. The area of investigation was located in Puszcza Zielonka ca 6 km NE of Poznań. Variability of groundwater levels, especially at shallow water locations, tends to show cyclic regularity, modulated for particular years by irregularity of weather conditions – mainly the precipitation and temperature, but physiographical features such as soil, vegetation, drainage network, water bodies, surface relief affect water conditions significantly nevertheless as a exclusively modulating factor. The results of the research prove the main effect of air temperature and precipitation on pattern of groundwater level dynamics in forest swamp habitats as a general regularity. The above mentioned conclusion supports additionally the results of recent research on climatic water balance for the area of experimental plots location. Anyway, the question arises about no expected distinction in groundwater level depth between the extreme years as far as precipitation is concerned (the years 2003, 2002 and 2005). No groundwater level dynamics decrease along with increase of groundwater level depth observed was another irregularity. Probably significant, modulating influence on groundwater dynamics in forest swamp sites may be ascribed to forest stand age. Along with maturing of forest stand, for example, changes the dynamics of stand biomass growth, which is strongly related to transpiration level and uptake of water from soil by plants. Described above phenomena may explain variability of groundwater level dynamics patterns for the experimental plots. The results of research were affected by employing relatively short groundwater level data series and very inconsistent meteorological conditions of the research period (pluvial and thermal). Thus, the current stage of research cannot justify drawing more accurate and distinct conclusions. The thesis of forest stand age impact on groundwater level depth variability requires broader explanation and cannot be supported or rejected basing on the current research results. The project opened in 2002 year is continued to achieve assumed research objectives.