| Natural grasslands in Yanchi county of Ningxia were eroded and degraded by wind and over-grazing. The demonstration region of vegetation restoration and desertification control of degenerate grasslands was established in 1986. Caragana Intermedia shrubbery was planted in rows to meliorate degenerate grasslands. The research on the soil water and vegetation restoration was conducted from 2002 to 2003 so as to make out the impact of planting density of C. intermedia on soil water and vegetation. The result showed that:(1) Dynamic changes of soil water content of C. intermedia grasslands of different density: Annual changes of soil water was greater and seasonal change was consistent with precipitation . At 0-100cm soil depth, soil water content of grasslands with C. intermedia of 1665 clusters /hm2 was the highest, and 2490 clusters / hm2 was second.(2) Impact of planting density of C. intermedia on soil physical and chemical character: the soil tight degree and the content of 2.0-0.2 mm Sand granule of C. intermedia grassland of 2490 clusters / hm2 were the lowest and its content of 0.2-0.02 silver sand was the highest, and C. intermedia grassland of 1665 clusters /hm2 was second. Capillary porosity of C. intermedia grassland 2490 clusters / hm was highest. In addition, contents of nitrogen, phosphor, potassium and organic matter of C. intermedia grassland of 2490 clusters / hm2 were the highest.(3) Soil water curve of C. intermedia grasslands of different density and its parameters inosculation: relation between soil water content and suction is power. At 0~20cm soil depth, diffusivity of C. intermedia grasslands of 2490 clusters / hm2 was the highest, and at 20~60cm depth, that of C. intermedia grasslands of 1665 A/hm2 was highest.(4) Water conservation of C. intermedia grasslands of different density : water conservation of C. intermedia grasslands of 1665 clusters / hm2 was the best and 2490 clusters / hm2 was second. In addition, at 0~40cm soil depth, water conservation was not better than that at 40-60 cm to all grasslands.(5) Water reserves of C. intermedia grasslands of different density: water reserves of C. intermedia grasslands of 2490 clusters / hm2 and 1665clusters / hm2 were better than other grasslands.(6) Water seepage of C. intermedia grasslands of different density: water seepage rate and cumulate seepage content in 30mins of C. intermedia grasslands of 2490 clusters / hm2 and 1665JA /hm were higher than other grasslands, moreover, stable seepage rate of C. intermedia grassland of 2490 clusters / hm2 was the highest and time of reaching stable seepage was shorter .(7) Evapotranspiration of C. intermedia grasslands of different density and transpiration of main plant species in community: Daily changes of transpiration rate and stomatal conductance of C.intermedia, Aneurolepidium dasystachys , Artemisia desertorums and Pennisetum centrasiaticum were douple peak curve, it was showed that transpiration sloped at noon. It was showed that evapotranspiration in spring and early summer was small, however, that was the bigger from July to September, because of high air temperature and soil water content. Evapotranspiration of c. intermediagrasslands of 2490 clusters / hm2 and 1665 A/hm2 were the bigger, but their water use efficiency were the highest.(8) Vegetation community character of C. intermedia grasslands of different density: total overground biomass, underground biomasses of C. intermedia grasslands of 2490 clusters / hm2 and 1665 cluster/hm2 were the biggest, moreover, their total root dry weight, root breadths and taproot length were the highest. In addition, coverage of C. intermedia grassland of 2490 clusters / hm2 was the biggest from June to October besides September. Species richness, diversity index, community evenness of C. intermedia grasslands of 2490 clusters / hm2 and 1665 clusters / hm2 were higher, and ecological dominant of C. intermedia grasslands of 1665cluster/hm2 was the highest. It was showed that their species composition rich and...
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