【作者】 徐荣；

【导师】 张玉发；

【作者基本信息】 中国农业科学院 ， 动物营养与饲料科学， 2004， 博士

【摘要】 宁夏盐池县受干旱风沙的影响，加上超载过牧，草场退化严重。1986年在柳扬堡乡建立了退化草场植被恢复与风蚀沙化防治技术示范区，带状种植了柠条(Caragana intermedia)，进行退化草场改良。我们于2002年和2003年进行了水分定位观测，通过研究柠条种植密度对土壤水分的影响，从水分和植被两方面作了系统的比较，确立了适宜的柠条密度，为在退化草地改良过程中，大面积营造柠条灌木提供了科学理论依据。主要研究内容和结论如下：(1)不同密度柠条草地土壤水分状况及其动态变化规律：土壤水分年际变化较大，土壤含水量季节动态主要决定于年内降水的季节性变化。0～100cm各土层，1665丛/hm~2草地土壤含水量最高，2490丛/hm~2柠条草地土壤含水量次之。而且，它们的土壤含水量均在土壤有效水范围内，可以被植物吸收利用。(2)不同密度柠条对土壤理化特性的影响：2490丛/hm~2柠条草地土壤的紧实度和2.0～0.2mm粗砂粒含最低，0.2～0.02mm的细砂粒含量最高，1665丛/hm~2次之。2490丛/hm~2柠条草地毛管孔隙度最大，土壤物理特性得到了改善。2490丛/hm~2和1665丛/hm~2氮、磷、钾和有机质含量均较高。(3)不同密度柠条草地土壤水分特征曲线和水分参数研究：土壤含水量和土壤吸力之间存在着幂函数关系。2490丛/hm~2柠条草地，0～20cm土层的土壤水扩散率D(θ)较大，1665丛/hm~2柠条草地20～60cm土层土壤水扩散率最高。(4)不同密度柠条草地土壤的持水性：1665丛/hm~2柠条草地持水性最好，2490丛/hm~2密度柠条草地居中。草地上层(0～40cm)土壤的持水性均比下层土壤(40～60cm)差。(5)不同密度柠条草地土壤蓄水量：2490丛/hm~2和1665丛/hm~2柠条草地蓄水量高于其他草地。(6)不同密度柠条草地土壤入渗特性：2490丛/hm~2和1665丛/hm~2柠条草地入渗速率、前30min累积入渗量高于其他草地。稳渗率以2490丛/hm~2和3330丛/hm~2柠条草地较大。达稳渗的时间以2490丛/hm~2和3330丛/hm~2柠条草地较短。总之，以1665丛/hm~2和2490丛/hm~2柠条草地的入渗性能比自然恢复草地和3330丛/hm~2柠条草地要好。(7)不同密度柠条草地蒸散特征和草地群落主要植物蒸腾特征：①主要植物种柠条、沙蒿、白草、赖草的蒸腾速率、气孔导度日变化规律均为“双峰”型曲线，都出现了明显的午间蒸腾午休现象。②蒸散季节变化规律表现出在春季和初夏蒸散失水量并不太大，在7～9月份，土壤的水分条件较好，土壤供水能力强，气温较高，这时植物生长旺盛，蒸散加快。③蒸散量以2490丛/hm~2柠条草地最大，其次是33300丛/hm~2和1665丛/hm~2柠条草地，自然恢复草地蒸散量最小。但2490丛/hm~2和1665丛/hm~2柠条草地水分利用率最大。(8)不同密度柠条草地植被群落特征：①2490丛/hm~2和1665丛/hm~2密度柠条草地地上总生物量、柠条林间草地地下生物量、柠条根地下生物量、根幅、主根长以2490丛/hm~2和1665丛/hm~2密度较大②2490丛/hm~2柠条林间草地盖度在6～8月份、10月份一直较大，明显地高于其它草地。9月份，2490丛/hm~2柠条草地盖度稍低于自然恢复草地。③1665丛/hm~2和2490丛/hm~2柠条草地物种丰富度、植物多样性指数和均匀度较高。1665丛/hm~2生态优势度最低，反映其由多物种组成，群落结构稳定。 2490丛/hm~2和1665丛/hm~2柠条灌丛草地，增大了植被盖度和生物产量。虽然草地蒸散量失水增大，但并没有引起土壤水分亏缺。因此，宁夏盐池干旱风沙区退化草场治理过程中，补种2490丛/hm~2和1665丛/hm~2柠条，达到了最优调控和充分利用水土资源，提高草地生产力的目的。更多还原

【Abstract】 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更多还原