Summary:

One of the most significant problems in contemporary climatology of cli-mate warming. Although not confirmed beyond any doubt, still numerous factors indicate climate change within the recent, relatively short period of time. Opinions presented in literature on the subject vary considerably - from extreme positions, forecasting disastrous effects in many regions worldwide to the claim that "the problem of climate change has been exaggerated against all proportions".
The Zielonka Forest is situated in mid-part of the Warta river basin, in the central part of the Wielkopolska region. The natural landscape is of postglacial type (Würm glaciation) with morainic plateaus - plain or rolling, gravel and san-dy soils as the main features. Pine and oak are the dominant tree species in forest stands. The predominant habitats are: fresh mixed coniferous forest, fresh conif-erous forest, moist coniferous forest and alder. Transitional climate of Puszcza Zielonka is distinguished by relatively significant nonstationality expressed e.g. by parameters of temperature and precipitation dynamics. For the period from 1848 to 2008 year, the directional changes of precipitation time series were not indi-cated at 0,05 level of significance. The trends are statistically insignificant for each month of the year, half-year, vegetation and hydrologic year periods. However the periodicity of annual precipitation was indicated. Dominating periods are 10,
7 and 6,7 year. The probability of annual precipitation is characterized by short-time series of similar values. The mean temperature time series for the investigated periods expressed statistically significant positive trend changes for March, May, November and December (at the 0,05 level). The trends for mean temperature time series of winter half-year, vegetation, hydrologic year periods were statistically significant, but for summer half-year insignificant at the 0,05 significance level. Annual precipitation likewise temperature time series is characterized by a perio-dicity. The dominating cycles are 7,6, 5,7 and 5,5-year. The probability values for precipitation manifested similar regularity as the probability for the temperature (shorter than 3- year sequence of similar values).