WATER-USE BY INTENSIVELY CULTIVATED WILLOW USING ESTIMATED STOMATAL PARAMETER VALUES

Large land areas in Sweden are planned to be planted with high producing, short rotation forest stands of willow in the beginning of the 1990s. In this paper the authors analyze Grip's (1981) lysimeter measurements with the help of a simple, yet physically realistic, evaporation model. The measurements were used to estimate the parameters affecting stomatal control in order to achieve a parameter set that could be used in model applications in all parts of Sweden. The model was then used with this parameter set to investigate the water balance of two hypothetical stands. The first simulation experiment aimed to find the upper limit of evaporation from an intensively cultivated willow stand with optimal irrigation and fertilization. The second experiment aimed to quantify what the evaporation might be from a normal stand, more extensively cultivated, but still with some access to irrigation and fertilization.