Studies On The Water Transportation Characters In SPAC System Of Mu Us Sandy Land In Ningxia

Water physiological characteristics of the two desert plants, that is, Caragana intermedia Kuang et H.C.Fu and Artemisia ordosica Krasch, water consumption of the individual and colony, the soil water characteristics, water balance of the mixed forest and the variation of water potential in SPAC were systematically studied in Sandy Land Shrab Garden, Yanchi County, Ningxia. The research results are as follows:The study shows that a dry layer forms under the surface, which is beneficial to the water conservation of the deeper layers. Water content of the soil is comparatively low in the area. It is found that the empirical equation θ = A·S^-B can well simulate the water characteristic curves of the soil during the low and medium suction (<1.5MPa). The study also demonstrates that the upper limit of available water is the soil moisture content corresponding to soil suction 0.05MPa and it is suitable to take 0.1 MPa as the dividing line of soil suction for readily available water and resistant available water.Both plants possess the physiological characteristic of adapting to the arid region. But their approaches to resist the aridity are different. Artemisia ordosica Krasch has higher transpiration rate. The water physiology indices of the two plants are affected by the environmental factors.When the plant is under the stress of drought the lowest leaf potential appears in advance. The resistance of water distribution in SPAC is high. The distinctly seasonal change of soil moisture is the common result of rainfall, evaporation from the forest floor and transpiration of the shrubs. The variation in leaf water potential is related with soil water content and rainfall. The pertinence between the atmosphere water potential, temperature and relative humidity is notable. The water potential gradient and space-time- variation are evident. The SPAC water potential gradient of Caragana intermedia Kuang et H.C.Fu is 1:14:355; that of Artemisia ordosica Krasch is 1:13:355.Evaportranspiration is the main form of water consumption. During the growth season of shrubs, increment of soil water content was negative, that is to say, vegetation density was excessive and needed to reduce.