In the current study the water balance in the process of natural regeneration in a managed Dinaric silver fir - beech forest and a virgin forest remnant wasinvestigated. We were interested in how managed and virgin forests influence the microclimate and water balance components. The influence of forest gaps on the microclimate and water balance components was shown for growing seasons in 2003 and 2004 with microclimatic process models. We used the chloride balance on a yearly basis, which needs analysis of Cl- concentrations in throughfall and soil solution, a simple water balance model (WATBAL), which calculates water balance on monthly basis and the BROOK90 model, which calculates water balance on daily basis. Meteorological data werecollected during growing seasons with four weather stations at selected locations. Simulated actual evapotranspiration was highest in the forest stand, lower for the regeneration stand and lowest in the gaps. Simulated drainage flux was highest in the gaps, followed by the regeneration stand and lowest in forest stands. According to calibration and verification based on measured throughfall fluxes and soil moisture contents and sensitivity analysis the BROOK90 model proved best at simulating water balance at selectedresearch sites. The model performed well in a number of options regarding vegetation type, horizontal and vertical structure of forest stand description as well as division of soil into more horizons. Daily intervals make the components of water balance more sensitive to weather conditions but in return increase the number of needed input parameters, which are rarely available for forest stands in remote areas.
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