【作者】 李萍；

【导师】 朱清科；

【作者基本信息】 北京林业大学 ， 复合农林学， 2012， 博士

【摘要】 陕北黄土区水土流失严重,生态环境脆弱,是植被恢复的重点区域之一。随着生态建设工程的实施,该区在植被恢复方面取得了显著成效,但缺乏理论和技术上的系统研究和总结。本文通过对生态恢复的影响因素分析,提出了植被生态恢复物质能量平衡假说,并深入分析了鱼鳞坑和水平阶两种整地模式的人工油松林植被恢复效果状况。7-8月份的鱼鳞坑内0-60cm土层土壤水分状况低于鱼鳞坑外部坡面,同时处于不同微地形条件下的鱼鳞坑的集雨效果存在差异性。半阳向陡坡和极陡坡采用80规格鱼鳞坑较适宜；缓坡采用80规格或者60规格等较小规格鱼鳞坑。雨季末水平阶整地人工油松林地各样地0—160 cm土层的平均土壤含水量为5.43%,雨季对各样地的土壤水分补给量很小。旱季末各样地土壤水分继续减小,0—160 cm土层的平均土壤含水量为3.87%。各样地碱解氮、速效磷、速效钾、有机质和全氮具有表聚性,尤其是0—10 cm土层表聚性显著；各样地pH值表现为碱性；0—100 cm土层的全磷、速效磷、全钾和速效钾平均含量为中等水平,有机质、全氮、碱解氮为低或很低水平。油松林地整体最佳邻体竞争范围为2.8m,基株受到的总体竞争强度随距离的增加而逐渐增大,得出邻体范围与基株的竞争强度的关系模型为：Cl=a+bL-1。油松的邻体竞争强度随着对象木胸径的增大而减小,呈现出幂函数关系Cl=aD-b。标准木解析的氮含量表现为：叶>果>枯落物>腐殖质>枝>皮>根>根头>干；磷含量表现为：腐殖质>果>枯落物>枝>叶>干>根>皮>根头；钾含量表现为：腐殖质>叶>根>枝>枯落物>皮>果>根头>干；碳含量表现为：叶>皮>枝>根头>果>根>干>枯落物>腐殖质。碳储量表现为沟坡上的油松林地碳储量最大,其次是水平阶整地的低密度林地,鱼鳞坑整地和未整地的相同密度林地碳储量小于水平阶整地的林地,水平阶整地的高密度林地碳储量也小于低密度水平阶整地的林地。标准木树高、胸径和材积的生长量均低于当地油松林生长平均值。胸径、树高较早进入成熟期,各样地的材积生长均处于加速生长期。在该区降水量不足、人工植被密度过大的情况下,水平阶整地方式通过使植物个体间的竞争力均一化,加剧了个体间的竞争,对低效林的产生起到了一定的促进作用。鱼鳞坑整地则是人为形成和扩大凹状微地形,使降水资源呈块状分布,建议该区造林采用鱼鳞坑整地模式。更多还原

【Abstract】 The ecological environment of northern Shaanxi loess area is fragile with the serious soil erosion, and it is one of the key areas of vegetation recovery. With the implementation of ecological construction projects, remarkable improvments of vegetation recovery were achieved, but the research and summary of theory and the technical system are still not perfect. The influencing factors of ecological restoration were analyzed with the previous research results, and a hypothesis concerning the material and energy balance of ecological recovery was built. The vegetation restoration effects of artificial Pinus tabulaeformis forest with two kinds of soil preparation were analysised.The engineering technology effects of the fish-scale pit and level bench were comprehensively researched. The results showed that during July and August, the average soil water contents inside the fish-scale pits were below the levels of external slope, and the effect of each fish-scale pits was different, which was mainly in the runoff periods. As a result, the catchment effects of each fish-scale pits were influenced by layout mode, construction technology and other factors.80 specification was suitable for the steep and very-steep slopes of semi-sunny, however 80 or 60 specifications were suitable for all the gradual slopes.The average soil moisture of soil layer of 0-160 cm at the end of rainy season was 5.43%, while that was only 3.87%at the end of arid season. It was suggested that recharge capacity of soil moisture during rainy season is small. All the nutrient substances of alkali-hydrolyzable nitrogen, available phosphorus, available potassium, organic matter and total nitrogen in soil have the property of accumulating in surface soil, especially the nutrients in the soil layer of 0-10cm. However, neither total phosphorus nor total potassium in all soil layers has this property. The soil of every site is Partial alkaline with the PH value greater than eight. The average capacity of Total phosphorus, total potassium and available potassium in the soil layer of 0-100cm is medium, while that of organic matter, total nitrogen, alkali-hydrolyzable nitrogen and available phosphorus is low or even extremely low.Within the pine plantation, the optimal growth distance was 2.8 m, which of 0-2cm lower diameter size was 4.0m, but it did not change obviously with the diameter size increasing. As the spacing increased, the number of neighbor trees became more and the total intraspecies competition intensified, but the trend of intensified became weaker. Model of the total competition intensity and interference zone was:Cl=a+bL-1. The competition intensity decreased gradually with the DBH increasing, the model was Cl=aD-b. The competition between the pines was greatest among trees with diameters of up to 2 cm. For sample trees, the order of Nitrogen content is leaf, fruit, litter, humus, branch, bark, root, root head, stem;and that of Phosphorus content is humus, fruit, litter, branch, leaf, stem, root, bark, root head; and that of Potassium content is humus, leaves, roots, branches, litter, bark, fruit, root head, stem; and that of Carbon content is leaf, bark, branch, root head, fruit, root, stem, litter, humus. The plot with the highest Carbon reserve is at the gully slope slope, followed by the plot with the low-density by the level bench. The carbon stocks of plots with the fish-scale and without site preparation are less than the plot with the level bench at the same density, and that with high density is less than low density the density by the level bench too. The tree height, DBH and volume growth were lower than the average of the local pine forests. The growths of DBH and tree height entered the mature stage, while the volume growth is in the accelerated growth period.Therefore, it is proposed that the measure of level bench contributes to the formation of low-quality and benefit forest in the semi-arid loess region through weaken the self-thinning of forest plantation which due to homogenization of competitiveness of individual trees, when precipitation is insufficient and density of plantation is too high. Fish-scale pit is site preparation that human formation and expansion could form concave-shaped micro-topography, which could make precipitation resources to re-distribute, so fish-scale pit is recommended in the area.更多还原