【作者】 杨永东；

【导师】 张建生；

【作者基本信息】 甘肃农业大学 ， 农业水土工程， 2008， 硕士

【摘要】 以黄土丘陵区定西市安家沟流域内的典型植被油松(Pinus tabulaeformis)、紫花苜蓿(Medicago Sativa)、沙棘(Hippophae rhamnoides)、天然草地(Onobrychis viciacfolia)、坡耕地(Prunus armeniaca)为研究对象,根据黄土丘陵沟壑区不同土地利用类型的土壤水分循环过程,大气降水分配特点,土壤侵蚀及径流量变化,分析了不同土地利用类型对土壤水分动态及水土保持效应,结果表明:(1)油松林地、坡耕地和苜蓿草地的平均地面径流量占同期平均降水量的比例分别为12.82%、7.17%和8.29%。天然草地和沙棘林地为3%左右。(2)不同年份的土壤水分有效性年际间均处于难效状态,未能达到田间持水量的60%;各植被类型土壤相对含水量比较稳定,沙棘的土壤相对含水量在50%左右,高于其他植被。(3)不同土地利用类型土壤水分均处于负平衡状态,在0~100cm土层水分亏缺量大小顺序为:坡耕地>油松林地>天然草地>沙棘林地。坡耕地的亏缺量在139.8~167.8mm之间,油松林地的亏缺量在120.5~139.32mm之间,天然草地的亏缺量在127.5~154.1mm之间,沙棘林地的亏缺量在100.5~127.5mm之间。沙棘林地对土壤水分具有更好的补偿效应。(4)对各土地利用类型土壤侵蚀次数及效应分析表明,苜蓿草地、沙棘林地、油松林地和天然草地径流量较坡耕地分别降低了12%、66%、21%和44%,土壤侵蚀量较坡耕地分别减少了58%、95%、77%和92%。沙棘林地和天然草地能够有效地减少径流及侵蚀的产生。(5)由于降雨分布不均匀,各月径流量和侵蚀量具有明显地不均等分布特征。径流和侵蚀主要发生在6-8月份,其土壤平均侵蚀量占总侵蚀量的89%,平均径流量占总径流量的86%。(6)同一强度雨强下,产沙量的大小取决于土地利用类型,各土地利用类型随雨强变化,产沙量增加大小顺序为:坡耕地>苜蓿草地>油松林地>天然草地>沙棘林地。不同降雨强度下,各土地利用类型产沙量随着降雨强度的增大而增加。各土地利用类型产沙量与降雨强度呈指数函数关系。(7)各植被类型随时间的变化,其减沙和减流功能不同。苜蓿随着时间的变化减流减沙功能逐渐减弱;沙棘林地的减流减沙功能随着树龄的增长而逐渐增强;天然草地的减流减沙功能比较稳定,年际变化不明显;而油松林地的减流率随时间的变化逐渐减小,减沙率逐渐增大。(8)对于不同土地利用类型土壤养分流失量分析表明,林地(沙棘林地、油松林地)养分流失量高于荒地(天然荒地、撂荒地)养分流失量。各土地利用类型的养分流失量在15°坡度达到最大,在10°~20°坡度范围内先增后减。更多还原

【Abstract】 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.更多还原