WATER-SUPPLY FROM THE GROUNDWATER TABLE AND THE GROWTH OF POPLAR - A CASE-STUDY

Forest growth and the growth of poplar in particular is related to water availability. Water supply through capillary rise from the groundwater table up to the rooted soil layers is a determining factor of the water balance. The water balance model SWATRER was used to explain the extreme growth differences in a 2-ha large poplar plantation. Water supply through capillary rise was estimated for 37 sites and related to different growth parameters. This study revealed that the simulation model SWATRER is a useful tool in growth site research. In particular, the site indexes S∞ and S10 showed a good correlation with water supply. Girth growth showed the highest correlation. In conclusion it was suggested that a poplar-specific girth growth model should be developed and the sink term parameters, potential evapotranspiration and interception should be defined more precisely. The results show the necessity for further research into clone-specific water requirements and the development of a simplified water balance model, adapted to growth-site research. © 1990.