A PRELIMINARY STUDY ON THE WATER EQUILIBRIUM AND EVAPOTRANSPIRATION IN PLANTATION OF PINUS TABULAEFORMIS

The water equilibrium and evapotranspiration have been deter mined in a Pinus tabulaeformis stand by regular measuring of soil water cont ent combined with hydrologic survey during the growing season in 1983 (May-Oct.).The results show that there is a balance between water income and water output in the experimental stand and evapotranspiration is the major way of water consumption in the stand.The major factor which influences the evapotranspiration rate is the soil water storage.The empirical equation established by step-wise regression analysis has been proved that it is available when predicting values are compared with the measuring values in 1984.