Kształtowanie się zasobów wodnych w małych zlewniach leśnych na obszarze Wielkopolski

Na podstawie pomiarów uzyskanych ze stacji meteorologicznej LZD Siemianice średnia z wielolecia 1975÷2006 roczna suma opadów atmosferycznych na badanym obszarze jest równa 560 mm (tabela 2). W półroczu zimowym w badanym wieloleciu średnia suma opadów wynosi 210 mm. Wartość średniej sumy opadów w półroczu letnim w danym wieloleciu jest równa 350 mm. Maksymalna zmierzona roczna suma opadów wyniosła 958 mm, natomiast najniższa jest równa 434 mm. W omawianym wieloleciu średnia roczna temperatura na analizowanym obszarze wynosi 9,0°C. Średnia z wielolecia temperatura powietrza w półroczu zimowym jest równa 2,4°C, natomiast w letnim 15,5°C. Najniższa temperatura w wieloleciu w półroczu zimowym wyniosła -0,4°C, a najwyższa 4,6°C, natomiast najwyższa temperatura w wieloleciu w półroczu letnim wyniosła 17,1°C a najniższa 13,6°C.

The research of water resource evaluation were carried out at three small forest catchment located at Wielkopolska region. G and G-8 catchments are located at Siemianice Forest Experimental Farm in southern part of Wielkopolska region. Hutka catchment is located at Zielonka Primeval Forest in central part of the region. The maximum water flow in analyzed G, G-8 ditches and Hutka water-course always appeared in winter half-years. Meanwhile water flow in analyzed watercourses were always significantly lower in summer half-years and periodically they disappeared. It was also indicated that increase of groundwater levels is strongly connected with water retention in winter half-years. Meanwhile decrease of groundwater levels and water content in soil caused by higher evaporation were observed in summer half-years which had significant role in water balances of these catchments. The research carried out in a different habitat conditions indicated the smallest changes of groundwater and total retention in swamp habitats: mainly in ash-alder swamp forest and moist broadleaved forest. Higher differentiation of water retention changes and groundwater levels was observed in moist mixed broadleaved forest, moist mixed coniferous forest, as well as in fresh mixed broadleaved forest and fresh mixed coniferous forest. It suggests the possibility of better usage of their retention capability. Optimum water level sustaining in forest habitat soils allows better usage of retain water was also indicated in the research, which is in accordance with forest needs and environmental protection requirements.