This thesis presents a series of methods for measuring water content and water availability in plants (pressure chamber, psychrometer), xylem water flow (sap flow meters), transpiration, and stomatal conductance (porometers). The physical principles and operational mechanisms of the individual methods are described, including their variants and the equipment required. The advantages and limitations of each method are also discussed. As a practical example of these methods the water status of a selected sycamore maple tree (Acer pseudoplatanus) and its responses to abiotic environmental factors were studied in the empirical part of the thesis. The measurements were carried out under real field conditions during the growing season. The main objective of the study was to illustrate the effects of meteorological parameters such as air temperature,
vapor pressure deficit (VPD), radiation and precipitation on water movement in a tree and to show how transpiration area, expressed as leaf area index (LAI) contributes to shaping the water status of the plant.
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