Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

The aim of this study was to evaluate homogeneity of air temperature and precipitation in the Wielkopolski National Forest Park during the period of 1848–2017. The Park is located in the mid-part of the Warta river basin, in the central part of the Wielkopolska region, near the city of Poznań. The area is located in the western part of the Wielkopolska-Mazovian climatic region. The natural landscape is of glacial type of Pleistocene and Holocene formation. Scots pine (Pinus silvestris) is the dominant species, but also Common oak (Quercus robur), Silver birch (Betula pendula), alder (Alnus glutinosa) and Red beech (Fagus silvatica) are present there. The predominant habitats include fresh broadleaved forest, fresh mixed broadleaved forest and fresh mixed coniferous forest. Climate change of the Park is distinguished by relatively significant stationarity expressed e.g. by parameters of temperature and precipitation dynamics. The time series of mean annual air temperature is not homogeneous. In the last 20 years a trend for rising air temperatures amounted to 0.04°C/year and it was 6 times higher than the same trend for the whole investigation period. The series of mean air temperature for the investigated periods showed a statistically significant positive trend for changes

for March, April, May, August, November, December and all-year (at the 0.05 significance level), with these trends amounting to 0.011, 0.009, 0.008, 0.007, 0.013, 0.010 and 0.006°C/year, respectively (Sen’s slope).
For the other months relevant trends are statistically non-significant. For the total of annual precipitation the hypothesis that the time series is statistically homogeneous may not be rejected. For the investigated period the directional changes of the precipitation time series were not indicated at the 0.05 level of significance. The trends are statistically non-significant for each month of the year and all-year periods.