The aim of the study was to compare the physical-chemical quality parameters of shallow groundwater quality in peat bogs of the Łęczna-Włodawa Lake District in the context of the occurrence of selected boreal species of plant relics: dwarfbirch (Betula humilis Schrank), downy willow (Salix lapponum L. ) and swamp willow (Salix myrtylloides L. ). Analyzes of shallow groundwater quality parameters included physical-chemical parameters: reaction (pH), electrolytic conductivity(EC), dissolved organic carbon (DOC), total nitrogen (TN), ammonium nitrogen (NH4), nitrite nitrogen (NO2), nitrate nitrogen (NO3), total phosphorus (TP), phosphate (PO4), sulfate (SO2), sodium (Na), potassium (K), calcium (Ca) and mag-nesium (Mg) by certified laboratory tests.
It was found that the natural hydrochemical specification of peat bogs is characterized by fluctuations associated with the dynamics of internal metabolism of peat ecosystems without the visible impact of anthropopressure. This is confirmed by the concentration of nutrients: TNat the study sites were within a broad range of mean values: 16.92–45.31 mg·dm–3; NH4 (0.55–0.76 mg·dm–3); NO2 (0.06–4.33 mg·dm–3); and NO3 did not exceed 0.2 mg·dm–3, and concentration of TP adopted mean values in a range of 0.22–0.42 mg·dm–3.
The studied physical-chemical factors of shallow groundwater were within the habitat preferences of the studied species, but in differentiated qualitative and quantitative ways determined optimal conditions for building the population of the studied species. Particularly values of TP lower than other obtained values in a range of: 0.08–0.32 mg·dm–3; PO4 = 0.1 mg·dm–3; TN = 2.2–21.2 mg·dm–3; NH4 = 0.1–0.46 mg·dm–3; DOC = 24.6–55.9 mg·dm–3, as well as higher than average pH values in a range of: 5.34–5.95 and concentration of Ca = 5.67–28.1 mg·dm–3 and Mg = 0.56–2.41 mg·dm–3, as well as EC = 72.1–142.3 μS·cm–1 can be treated as a condition favouring proper development of the population of dwarf birch. For Salix lapponum: a reduced level of values of nitrogen fractions (TN = 3.01–18.84 mg·dm–3; NH4 = 0.1–0.41 mg·dm–3), a reduced level of values of phosphorus fractions (TP = 0.09–0.44 mg·dm–3; PO4 = 0.1–0.44 mg·dm–3), part of ions (Ca = 4.39–19.63 mg·dm–3; Mg = 0.77–3.37 mg·dm–3), pH = 5.9–6.4, EC = 124–266 μS·cm–1 and DOC = 24.1–57.5 mg·dm–3. For the equally studied Salix myrtylloides, such conditions were met by: TP = 0.1–0.41 mg·dm–3; PO4 = 0.1–0.18 mg·dm–3, DOC = 27.5–50.9 mg·dm–3, pH = 5.3–5.94 andEC = 62.2–139.3 μS·cm–1.
The purpose of the paper is to analyze the spatial variability of precipitation in Poland in the years 1981–2010. The av-erage annual rainfall was 607 mm. Precipitation in Poland is characterized by high spatial and temporal variability. The lowest annual precipitation was recorded in the central part of the country, where they equaled 500 mm. The highest annual precipitation totals were determined in the south, equaling 970 mm. The average precipitation in the summer half-year is 382 mm (63% of the annual total). On the basis of data from 53 climate stations, maps were made of the spatial distribution of precipitation for the period of the year and winter and summer half-year. The kriging method was used to map rainfall distribution in Poland. In the case study, cross-validation was used to compare the prediction performances of three periods. Kriging, with exponential type of semivariogram, gave the best performance in the statistical sense. Their application is justices especially in areas where landform is very complex. In accordance with the assumptions, the mean prediction error (ME), mean standardized prediction error (MSE), and root mean-square standardized prediction error (RMSSE) values are approximately zero, and root-mean-square prediction error (RMSE) and average standard error (ASE) reach values well below 100.