| By the long period case studied in the Losses Plateau demonstration district, combining with the investigation data analysis, and chose five types typical vegetation, such as Pinus tabulaeformis, Medicago Sativa, Hippophae rhamnoides, Onobrychis viciacfolia and Prunus armeniaca, were selected in DingXi in gully and hilly of Losses Plateau, analysis the basic of soil moisture recycle ,rainfall distribution characteristic and soil erosion of different vegetation in gully and hilly region of Losses Plateau and summarize the dynamic changes of soil moisture and soil conservation. The purpose was supplying scientific basis for ecological resume. The results showed:(1) The ratio of ground even runoff flow occupied the even rainfall in same period was different in different land use.It was about 3%~12.82%.The natural grass and Hippophae rhamnoides were least. It was about 3%. The ratio of Pinus tabulaeformis was most.It was about 12.82%. The ratio of farmland and manual grassland were about 7.7% and 8.29%.(2) According to the compared with the soil moisture in different years among different vegetation, the soil moisture was difficult to utilize by vegetation. The comparative soil moisture was just occupied by 60% of field capacity, and the comparative soil moisture was stable. The comparative soil moisture of Hippophae rhamnoides is highest. It is 52.6%. And The other was about 45%.(3) Acording to the water balance of different vegetation,soil water content of the vegetation was deficiency.The depth at 0~100cm, the soil moisture of different land use was surplus and deficiency. All of quantity of water surplus and deficiency were above 100mm. Hippophae rhamnoides was least than others and the quantity of farmland was highest. The quantity of farmland was about 139~167.8mm. It was about 135.0~155.3mm of Medicago Sativa, and it was 100.5~127.5mm of Hippophae rhamnoides, and it was 120.5~139.2 of Pinus tabulaeformis. and it was 127.5~154.1mm of natural grassland.(4) According to the times and effects of the soil erosion, compared with farmland, the runoff of Medicago sativa, Hippophae rhamnoides, Pinus tabuleformis and natural grassland were decreased by 12%,66%,21%,44% and the soil erosion were decreased by 58%,95%,77%, and 92%. Hippophae rhamnoides and natural grassland could decrease runoff and soil erosion.However, the effects of Medicago sativa and Pinus tabuleformis were limited.(5) According to the study time changes on the effects of soil and water conservation of different vegetation, the results showed, the runoff and sediment in different months had the variously different characteristic because of rainfall distribution, such as inequality. The runoff and soil erosion mainly appeared from June to August. In these months, the means of erosion occupied about 89% of total erosion, and the means of runoff occupied about 86% of total runoff.(6) In the same rainfall intensity, the sediment generation quatity was related to the land use. The sort of the sediment generation of different land use with the change of rainfall power was Farmland>manual grassland>Pinus tabuleformis>natral grassland> Hippophae rhamnoides. In different rainfall intensity, the sediment generation in different land use style could be described by exponential function.(7) With the growth of the vegetation, the reduction of soil erosion and runoff was different to different vegetation. The ability of reduction soil erosion and runoff of Medicago sativa was gradually decreased, even disappeared. The ability of reduction soil erosion and runoff was gradually strengthen with the ages of Hippophae rhamnoides. The ability of natural grassland was stable, the changes was insignificant among years. However, to Pinus tabuleformis the ability of reduction runoff was gradually decreased and the ability reduction of soil erosion was gradually increased.(8)According to the analysis of the soil fertilizer loss on different land use style from 10°~20°, the soil fertilizer loss of woodland was higher than wilderness land. And the soil fertilizer on slope 15°was highest, below 15°it would increase and exceed 15°, it would decrease.
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