【作者】 王晶；

【导师】 朱清科；

【作者基本信息】 北京林业大学 ， 复合农林学， 2011， 硕士

【摘要】 对于黄土高原地区植被恢复与生态环境建设工作而言,其制约的关键性因子是水分分布条件。本研究论文旨在探索在不同环境因子影响下陕北半干旱黄土区不同规格鱼鳞坑土壤水分条件的变化规律,并对困难立地条件下工程造林关键技术提供理论基础、科学依据和决策支撑。本研究选择了陕西省延安市吴起县为特征试验区域,通过对土壤样本的分层采样及处理、土壤水分含量测定和数学分析方法来探索陕北半干旱黄土区不同规格鱼鳞坑土壤水分变化规律。主要得出以下结论：(1)通过研究吴起县降水资源分布规律得出：试验区50年来平均降水量呈下降趋势,年际间的降水变幅较大,其多水年和少水年的降水量可相差1倍～3倍,各年年内的降水分布曲线多呈典型的单峰型。降水主要集中在植物生长季节(5月～9月),在生长季内各月的降水量也不尽相同,其中7月～8月的降水量占生长季降水的58%,而5月～6月的降水量仅占生长季的24%。降水量的季节分配极不均匀,降水四季分配比例为：春季降水量(3月～5月)占全年的15%,夏季降水量(6月～8月)占全年的51%,秋季降水量(9月～11月)占全年的22%,冬季降水量只占全年的12%。生长季4月～9月80%保证率下的降水量为306mm,占同期平均降水量的76.0%。该地区春季降水变率小、保证率较高；雨季降水变率相对较大、保证率不高。(2)通过对不同规格鱼鳞坑土壤水分变化规律的研究得出：坡而上进行鱼鳞坑整地,可以有效的拦截地表径流,减少坡面水土流失,同时也起到了改善坡面上壤水分的作用,从而为植被生长创造了良好的水分条件。不同规格鱼鳞坑土壤含水量的季节变化趋势总体表现为“两升两降”,据此,可将不同规格鱼鳞坑土壤含水量动态变化依据季节变化划分为四个阶段：上壤水分缓慢恢复期(10月～次年开春)、上壤水分下降期(4月～6月)、土壤水分补充恢复期(6月～8月)和土壤水分消退期(8月～10月)。在2009年10月、2010年6月和10月,不同规格规格鱼鳞坑的上壤水分含量差别相对较大,而2010年4月和8月,不同规格鱼鳞坑的土壤水分含量差别较小或相近。在缓坡上,鱼鳞坑上壤含水量随着规格的增大而增大,其中半阳向缓坡上大鱼鳞坑提高的土壤含水量为2.1%、半阴向缓坡上大鱼鳞坑提高的土壤含水量为1.85%、阴向缓坡上大鱼鳞坑提高的土壤含水量为2.56%；在陡坡和极陡坡上,不同规格鱼鳞坑土壤含水量相对最大的是中鱼鳞坑,其次为大鱼鳞坑与较小鱼鳞坑,土壤水分含量最小的是小鱼鳞坑,半阳向陡坡上,中鱼鳞坑提高的土壤含水量为1.59%、半阳向极陡坡上,中鱼鳞坑提高的土壤含水量为1.92%。(3)通过对不同规格鱼鳞坑土壤水分影响因素的分析得山：降雨、坡度和坡向对鱼鳞坑土壤含水量变化规律都有显著性影响,而规格对鱼鳞坑土壤含水量变化规律的影响不显著。降雨的影响相对比较显著,降雨对不同规格鱼鳞坑土壤水分的影响程度大小为小鱼鳞坑>较小鱼鳞坑>中鱼鳞坑>大鱼鳞坑。不同规格鱼鳞坑土壤水分与坡度因子的相关性随着鱼鳞坑规格的增大而依次增强,即鱼鳞坑规格越大的土壤含水量受坡度因子的影响越大。不同规格鱼鳞坑土壤水分与坡向因子的相关性随着鱼鳞坑规格的增大而增强、减弱再增强,即大规格鱼鳞坑的土壤含水量受坡向因子的影响越大,其次是较小鱼鳞坑和中鱼鳞坑,小鱼鳞坑的上壤含水量受坡向因子的影响最小。更多还原

【Abstract】 Soil moisture is the main restricted factor in the construction of vegetation restoration and ecological environment in Loess Plateau.This research paper seeks to explore the fish-scale pits of different specifications in the semi-arid Loess Plateau of northern Shaanxi province under the different influence of environmental factors. And this study can provide a theory, scientific basis and policy support to afforestation key technology under difficult site conditions. This thesis has Wuqi County in Yan’an in Shaanxi Province as the experimental region, explore the fish-scale pits of different specifications in the semi-arid Loess Plateau of northern Shaanxi province by stratified sampling of soil samples, determination of soil water content and mathematical analysis. The major conclusions are as follows:By studying the distribution of precipitation of Wuqi County indicated the average annual precipitation decreased in the past 50 years, annual precipitation had the large amplitude, the more water and less water in precipitation can have a difference of 1 to 3 times. During the each year,the distribution curve of the precipitation had mostly typical single peak. Rainfall mainly concentrated in the growing season (5 to 9 months), the precipitation for each month are not the same in the growing season, rainfall was accounted for 58% of the precipitation in growing season between 7 to 8 months, and it was accounted for only 24% of the precipitation in growing season between 5 to 6 months. Seasonal distribution of precipitation was uneven, precipitation distribution ratio of the four seasons as followed:the precipitation in spring (3 to 5 months) was accounted for 15% of the year, the rainfall in summer(6 to 8 months) was accounted for 51% of the year,the rainfall in autumn (9 to 11 months) was accounted for 22% of the year, the precipitation in winter was accounted for only 12% of the year. To ensure that 80% of the precipitation rate was the 306mm in growing season (4 to 9 months), which was accounting for 76.0% of average precipitation over the same period.The variability of precipitation in rainy season was more larger than in spring,but the guarantee rate of precipitation in rainy season was more less than in spring.Fish-scale pit could effectively intercept surface runoff and reduced soil erosion in slope, and it also played an important role in improving soil moisture, so it created favorable water conditions for vegetation. The seasonal variation trend of soil moisture in fish-scale pits of different specifications overall performance as " two litres of two drop," accordingly, the dynamic changes of soil water in fish-scale pits of different specifications was divided into four stages:soil moisture slow recovery (October to next spring), soil moisture decline period (4 to 6 months), soil moisture complement recovery (6 to 8 months) and soil moisture subsidise period (8 to 10 months). The soil moisture content in fish-scale pits of different specifications was relatively large in October 2009 and 2010 June and October, and in April and August 2010 the soil moisture content in fish-scale pits of different specifications was smaller or similar.In the gentle slope, the soil moisture increases with the specifications of fish-scale pits, the big fish-scale pits improve soil moisture content was 2.1% in half-sunny slope, the big fish-scale pits which in half negative slope increase soil moisture content was 1.85%, the large scale pits to raise the soil moisture content was 2.56%; in terms of soil water on steep and extremely steep slopes, specifications may be ranked in the descendant order of middle, large, small and smaller, on semi-sun to steep slopes, the soil moisture of middle fish-scale pits improved 1.59%, semi-sunny to the extremely steep slopes, the middle fish-scale pits improved soil moisture content was 1.92%.Rainfall, slope and aspect on the variation of soil moisture in fish-scale pits had a significant impact, while the size of the fish-scale pits was not significant to the variation of soil moisture. In terms of the influence on rainfall to the soil moisture, in the descendant order of small, smaller, middle and large. The variation of soil moisture in fish-scale pits of different specifications correlation with slope was increased with increasing specifications. In terms of soil water that was influenced by aspect, specifications may be ranked in the descendant order of large, small, middle, and smaller.更多还原