Simulation of water productivity and soil desication of Caragana microphylla shrub land on semi-arid hilly region of the loess plateau

By setting the databases of soils and weather,revising and validating the adaptability of the parameter of Caragana microphylla,the dynamic changes of water potential productivity of Caragana microphylla shrub land and available soil water amount in 0～9 m soil layers were simulated with WinEPIC model at Guyuan on loess hilly areas.The results show as following: Caragana microphylla growth depended on soil water and precipitation in the earlier 10 years.Water potential productivity of Caragana microphylla shrub land stabilized and the brush land had no water stress but desicated soil layers occurred.The water deficits of the shrub land aggravated as root deepening of Caragana microphylla.Simulated water productivities of Caragana microphylla brush land declined with fluctuation gradually.Simulated available soil water amounts in 0～9 m soil layers of Caragana microphylla shrub land at Guyuan declined obviously with fluctuation,decreased by 101.0 mm/a in the earlier 10 years and available soil water amounts fluctuated with rainfall change for a long period at low level in the later.So,seasonable growth years for soil water sustainable use on Caragana microphylla shrub land are about 10 years on semi-arid loess hilly region.