EXPERIMENTAL INVESTIGATIONS CONCERNING SP RUCE [PICEA-ABIES (L) KARST] WATER-BALANCE

In an eighty-seven-year-old spruce stand of a hydrological catchment a rea we measured and estimated the atmospheric evapotranspiration capac ity, the transpiration of a single tree, water uptake by roots, sap fl ow and water storage of the tree as well as the brook runoff. All thes e meteorological, physiological, soil-physical and hydrological variab les oscillate periodically in the course of a day with a phase shift i ncreasing in the direction from the atmosphere through the tree to the sail and the brook. This means that the suction of the atmosphere is propagated in the same direction. In this coupled system we can determ ine the water balance of the tree and especially the transpiration by the measuring of the above variables. The inclusion of runoff allows t he areal generalisation of the single tree measurements.