Estimation of Evapotranspiration of Trees and Adaptive Faculty of Water in Arid and Subarid Regions of Gansu Province

Using Zhang Baokun and H. L. Penman’s climatological method, the evapotranspiration of tree growing seasons is estimated in every county and city of arid and subarid regions of Gansu Province, and compared with the observed and investigated data. The results show that the two kinds of estimations could present the water requirements of fuel forest and timber forest, and the actual water resource regime are given when mean annual and daily temperature are higher than or 10 ℃ in various locations.Based on the water consumption indices of tree growing seasons and the actual water resource regime, the water adaptive faculty of trees in different climate and vegetation regions is determined using the actual wettability method