半干旱黄土丘陵区柠条林水分生产力和土壤干燥化效应模拟研究

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

建立固原半干旱丘陵区WinEPIC模型土壤数据库、气象数据库,修订柠条作物参数,验证模型的精度及在该区适应性,在此基础上对黄土高原丘陵区柠条林地水分生产力和9 m土层土壤有效含水量进行30 a长期动态模拟研究。结果表明,前10 a柠条生长主要依靠土壤储水和降水,水分生产潜力稳定且无水分胁迫,但已出现土壤干层;生长10 a以后随着柠条根系的下伸,土壤水分亏缺加剧,水分生产力随降水量变化呈波动性下降趋势。9m土层逐月土壤有效含水量均呈现明显的波动性降低趋势。模拟柠条生长初期（1-10 a）9 m土层土壤有效含水量以101.0 mm/a的速度递减,此后长期在较低水平上随降水量变化而波动。由此得出,固原丘陵区柠条水分持续利用的合理年限为10 a左右。

By setting the databases of soils and weather, revising and validating the adaptability of the parameter of Caragana rnicrophylla, 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 rnicrophylla growth depended on soil water and precipitation in the earlier 10 years. Water potential productivity of Caragana rnicrophylla 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 rnicrophylla brush land declined with fluctuation gradually. Simulated available soil water amounts in 0- 9 m soil layers of Caragana rnicrophylla 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 rnicrophylla shrub land are about 10 years on semi-arid loess hilly region.