| Based on the theory of soil-plant-atmosphere continuum, the paper studies the rule on evapotranspiration of Locust forest in semi-arid region of Loess plateau. The problems are discussed as follows:· Rule on evaporation of Locust tree with different density in 1998 and 1999.· Rule on soil evaporation of Locust forest with different density in 1998 and 1999.· Rule on Actual evapotranspiration of Locust forest in growing season with different density in 1998 and 1999.Main research results are as follows:· On basis of establishing modles on all parameters such as net radition in forest canopy, light reduction coefficient, forest canopy stoma resistance and boundary layer resistance, Penman-Monteith model is provided for calculating evaporation of Locust forest in experimental zones in 1998 and 1999. The results shows the equation is feasible.· In growing season the maximum soil evaporation value shows in July. The soil evaporation in growing season changes as pricipitation and soil water. In different water harvesting measures, the rule is conventional forest(100%) > tamped forest(69.7-78.3%) > tamped&lichen forest(55.1-62.0%).· Comparing between the oriental fluxe plane method and the indirect method, the results relatively errors are under 10%. It shows the oriental fluxe plane method can exactlu reflect the actual evapotranspiration.· The ratios between evaporation and evapotranspiration are between 0.20 and 0.70, and the maximum value is 0.71. The larger water harvesting area, the more waterharvesting quantity and the bigger the ratio between the evaporation and evapotranspiration. On the same density, the ratio of the tamped&lichen forest is largerthan the ratio of the tamped forest, and their ratioes are both larger than the ratio of the conventional forest.
|
PDF Full Text Request