Badania dotyczące małych zbiorników wodnych w lasach, odgrywających w kształtowaniu gospodarki wodnej terenów leśnych niezwykle istotną rolę, prowadzone są w ostatnich latach na coraz szerszą skalę. Wielu autorów podkreśla duże znaczenie śródleśnych oczek wodnych, będących elementem małej retencji, w kształtowaniu zasobów wodnych przyległych siedlisk, zwłaszcza w okresach posusznych, w których zretencjonowane w tych zbiornikach wody zasilają wody gruntowe terenów przyległych [4, 5]. Zasilanie to jest ważnym elementem gospodarki wodnej zlewni leśnych, która w dużej mierze może decydować o trwałości lasu. Według Rozwałki i Wiśniewskiego [10] aby zwiększyć korzystny wpływ lasu na bilans wodny kraju, poza zwiększeniem lesistości, należy w lasach odbudować małą retencję. Według tych autorów zwiększenie zdolności retencyjnych terenów leśnych możliwe jest przez właściwe gospodarowanie zasobami wodnymi w małych zlewniach, z śródleśnymi oczkami wodnymi. Jednym z wielu dokumentów mówiących o konieczności ochrony i odbudowy małych zbiorników wodnych na terenach leśnych jest Polityka Leśna Państwa [9]. W aneksie 2 tego dokumentu stwierdzono, że w ramach programu ochrony ekosystemów leśnych należy pozostawić w stanie zbliżonym do naturalnego, lub odtworzyć śródleśne zbiorniki wodne. Dlatego też konieczne są dalsze badania i analizy gospodarki wodnej w mikrozlewniach leśnych z śródleśnymi oczkami wodnymi, które przyczynią się zarówno do ochrony samych oczek, jak i zasobów wodnych w ekosystemach leśnych ich zlewni. Celem pracy było określenie zmian stanów i zapasów wody w zlewni śródleśnego oczka wodnego w średnim, pod względem sumy opadów, roku hydrologicznym.
EN
The paper presents the results of the researches in catchment of pond No1, located at Siemianice Experimental Forest Farm in Wielisławice Forestry. The catchement area of investigated ponds is 7,6ha, forestation 100%, and with dominating haplic regosol soils, is situated is a part of Niesób catchment - left-side tributary of Prosna River. The results indicates that meteorological conditions course, especially mount and distribution of precipitation as well as air temperature have significant impact on groundwater levels and water storage changes in analyzed pond catchment in 2006/2007 hydrological year which was average according to precipitation sum. Obtained results confirmed that water storage changes in the forestall pond No 1 were higher than retention changes in neighbouring forest habitats. Increase of water storage in the pond were of 420 mm, 277 mm in neighbouring moist mixed broadleaved forest and 303 mm in fresh mixed coniferous forest in winter half-year. Decrease of water storage in the pond and neighbouring forest habitats were observed in summer half-year with precipitation sum which was 32 mm lover than average one. The decrease of water storage in pond was 420 mm and in neighbouring area picked from 285 mm in moist habitat (LMw) to 312 mm in fresh habitat (BMśw). According to computing and analyses it was indicated that water stored in the catchment in mid-wet half-year allowed to compensate water retention decrease which appeared in summer half-year. Therefore only small water storage of 6 mm was observed in 2006/2007 hydrological year. Sums and distribution of atmospheric precipitation and changes of air temperature in individual months of winter and summer half-years of described hydrological year 2006/2007, had decisive impact on dynamics of water levels and water storage in forest pond and its catchment.
3
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The paper is based on the investigations carried out in the area of the Siemianice Experimental Forest Complex of Agricultural University of Poznań, in the catchments of two forest ponds.The site of the research is located within the Southern-Wielkopolska Lowland situated within the Wieruszowska Wysoczyzna. The ponds in focus are similar as far as their area is concerned i.e. the first one: 0,13 ha and the other one:0.10 ha, and depth reaching 1m. The catchment surface of the first pond measures 7.6 ha while the other one 19,4ha. The areas neighbouring the ponds are occupied by moist habitats and in the upper parts fresh mixed habitats covering 90% of the surface. The catchments are dominated by pine stands aging from 86 to 110 years. Pond 1 situated in a small size depresion is of thawed - out type. The other pond (number 5) situated at the foot of the morene slope is intensively fed by stream waters which provide a continuing water outflow from the pond in the course of the year. Field research comprising: measurements of both water levels in the ponds and groundwater levels, regular registration of outflows from pond 5 and pedological procedings was conducted in 1999/2000 and 2000/2001 hydrological years. The output of the research of water balances of the two small ponds were analysed against the background of and in relation to the characteristic groundwater levels of the neighbouring forest areas. Existing retentional capabilities of the catchments of the two discussed ponds indicate their varied influence, as small retentional reservoirs, on water management in the close forest habitats areas.Pond number 5 situated at the foot of a morene slope and intensively fed by stream waters, providing a continual and insignificantly changeable outflow from the pond in both half-years, shows only slight amplitudes of oscillations of water levels i.e. 0,4-2 cm. Fairly static water levels in the pond stabilize lowering water levels in the neighbouring forest areas, especially in the period of drought. The levels of the water in pond 1 are strictly connected with the existing groundwater levels in its catchment. The amplitudes of the oscillations of water levels in the pond are slightly lower than the ones of groundwater levels in the neighbouring forest habitats. In winter hydrological half-years, spring perionds and rainy summer seasons, the pond is fed by groundwaters, and at the time of summer and autumn droughts it feeds groundwaters itself. The results of the evaluations of water balances of the two catchments indicate that water circulation of pond 1 is more tightly connected with water cycling in the catchment than in case of pond 5. Varied water inflowsreaching the ponds are significant, apart from the amplitudes of oscillations of water levels in the ponds and groundwater levels and pond and catchments water retention connected with it. In water balance of pond 5, both in winter and summer half-years they present similar values due to continual stream water feeding process. The research shows that ground inflows to pond 1 are meaningfully varied and retained waters feed groundwaters of the neighbouring forest habitats in the periods of drought.