AbstractRecently, the term global warming and the effects of drought on forest stands have become increasingly common and we fear that this trend will grow. Beech is considered to be the focal point of many forest ecosystems and is important in stabilizing it. Its stands are important for groundwater production and the regeneration of depleted soils. The thesis focuses on the dynamics respectively. evaluation of the adult beech water regime in selected months for 2017 and 2018. The main aim of the work was to analyze the transpiration flow (sap flow) in relation to the external conditions and the availability of water in the soil, as these factors affect the physiological processes most. The research took place in Bienska dolina. An experimental area was established at this site where sap flow was measured on 12 samples. The results confirmed the great influence of meteorological factors on transpiration. It has been shown to be closely related to global radiation, saturation and potential evapotranspiration. It has also been confirmed that the rate of dependence on these variables is decreasing with the advent of drought.