| By analysing soil water regimes for kinds of vegetation, this paper broadly discusses the characteristics of soil desiccation by vegetation and mechanism of its genesis so as to properly understand what it is and provide bases for conditioning it. It is indicated that soil desiccation by vegetation is characterized by relative stability, and field steady moisture might be taken as a quantitative index to measure it. Under droughty climatic conditions characterized by less rain and strong evaporation,soil desiccation by vegetation is liable to occur because of deep groundwater level in the Loess Plateau, but it isn't inevitable for vegetation construction in the Loess Plateau. Constructing large-area vegetation with striking water consumption, high community density and pursuing high community productivity is crucial to its genesis. Soil desiccation might be conditioned by understanding the duality of the specialites of species composing artificial vegetation, necessity for reasonably disposing community structure, and difference in individual competition between artificial communities and natural communites. So soil desiccation occurance generally by vegetation should not be taken as a reason to doubt or even negate forest and grass vegetation construction in the Loess Plateau. |