【作者】 佘雕；

【导师】 吴发启；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2010， 博士

【摘要】 黄土高原地区广泛种植的水土保持型灌木林地,既可防治水土流失,又对该地区的植被恢复和生态环境建设具有重要意义。本研究针对黄土高原地区的主要水土保持型灌木林地的土壤质量问题,以宁夏固原上黄试区的柠条林地、甘肃定西团结乡高泉沟流域的沙棘林地和陕西延安飞马河流域的天然次生林地为研究对象,通过野外调查采样,室内土壤分析,并结合方差分析、相关性分析、因子分析、逐步回归分析等数理统计方法,系统研究了黄土高原地区这三种水土保持型灌木林地土壤质量的基本特征、剖面及水平分异,优选出了灌木林地土壤质量评价的指标体系及评价模型,并对这三种灌木林地的土壤质量进行了综合评价。主要结论如下:1.三种灌木林地土壤的机械组成随坡向的变化趋势为砂粒及粉粒含量阴坡>半阴半阳坡>阳坡,而粘粒含量则表现为阴坡<半阴半阳坡<阳坡;随坡位的变化趋势为:砂粒及粉粒含量坡上部>坡中部>坡下部,而粘粒含量却为坡上部<坡中部<坡下部。土壤团聚体含量在不同坡位上的变化规律是坡上部>坡中部>坡下部;在不同坡向间则为阴坡>阳坡>半阴半阳坡。灌木林地对土壤团聚体的改良效果为沙棘林地>天然次生林地>柠条林地。20年生柠条与10年生柠条相比砂粒含量相对减少,粉粒和粘粒含量均相对增大,土壤相对“粘化”;总团聚体含量、平均重量直径以及不同粒径的土壤团聚体含量均有少量增加。灌木林地土壤容重均随着剖面深度的增加而逐渐增大,对土壤容重和孔隙性能的改良作用次序为:沙棘林地>柠条林地>天然次生林地。2.三种灌木林地表层有机质、全氮、碱解氮、速效钾、CEC、CaCO₃含量等基本都属“中”水平,其中仅柠条林地和天然次生林地的碱解氮属“低”水平,天然次生林地速效钾属“较高”水平,柠条林地CEC属“低”含量水平,CaCO₃含量属“高”水平。柠条和沙棘林地表层全磷含量均属“高”水平,天然次生林地则为“较高”水平;速效磷含量均属“极低”水平,全钾含量均属“较高”水平;三种灌木林地表层有机质、CaCO₃、速效钾含量和电导率EC均随剖面深度的增大而降低,各层次间具有显著性差异;而全氮和碱解氮、全钾含量在剖面上无明显分异。三种灌木林地土壤有机质和全氮含量在不同坡位上具有相似的分异规律,柠条林地和沙棘林地表现为坡上部>坡中部>坡下部,而天然次生林地却相反,从坡上部、坡中部到坡下部依次增大。全磷量和速效磷在不同坡位上的分异规律都是从坡上部-坡中部-坡下部依次增大。土壤有机质、全氮、全磷和速效磷在不同坡向间的变化趋势相同,均是阴坡>半阴半阳坡>阳坡,而碱解氮没有表现出坡向分异。全钾和速效钾含量在不同坡位及不同坡向上的含量变化很小。与10年生柠条林地土壤相比,20年生柠条林地表层土壤中全磷,速效磷、CaCO₃含量和pH值等四项土壤化学指标的数值有小幅度的降低,而有机质、全氮、速效氮、全钾、速效钾、阳离子代换量（CEC）和电导率（EC）等化学指标的数值均有所增大。总体来看,随灌木林地生长年限的加长,土壤的各种养分含量及土壤综合质量均逐渐提高。3.林地表层土壤酶的稳定性为碱性磷酸酶>蔗糖酶>脲酶。土壤蔗糖酶和碱性磷酸酶的活性顺序均为:柠条林地>沙棘林地>天然次生林地,而脲酶的活性依次为:柠条林地>天然次生林地>沙棘林地。三种酶的活性具有明显的垂直分异性,都随着剖面土层加深而下降。从水平分异来看,坡向对土壤酶活性的影响不显著。而坡位对土壤酶的活性有明显的影响,坡上部酶活性高于坡下部,坡中部波动较大。土壤酶活性随灌木林龄的增加而增大。4.在15项物理指标（含有机质）中,除了粗粘粒、细粉粒、粗粉粒、含水量等4项土壤物理属性外,其余11项土壤物理性质间绝大多数呈现出极显著相关。12项土壤化学指标间也大多表现出显著及极显著相关。土壤理化性质的相关分析结果表明,细粘粒与有机质、全氮、速效氮、全磷、速效磷、全钾、速效钾、阳离子代换量和CEC等8项化学指标均呈极显著正相关,而与pH值和CaCO₃含量之间呈极显著负相关。细粘粒、细粉粒、细砂粒和有机质含量对土壤养分的保蓄及土壤质量的改善具有积极意义。三种灌木林地土壤的脲酶、磷酸酶和蔗糖酶三者之间均表现出极显著正相关关系。5.优选出了黄土高原地区灌木林地土壤质量评价的指标9项:有机质、全氮、全磷、全钾、碱解氮、蔗糖酶活性、CEC、CaCO₃和含水量。建立了黄土高原地区灌木林地土壤质量评价指标体系及加权和法指数评价模型并评价了三种灌木林地土壤的综合质量,结果表明土壤质量的高低次序为沙棘林地>柠条林地>天然次生林地。土壤质量分级表明沙棘林地为Ⅱ级,土壤质量较高;柠条林地和天然次生林地均为Ⅲ级,土壤质量中等。建议黄土高原地区灌木造林时的树种选择应首选沙棘,次之为柠条,最后为天然次生林。灌木林地土壤质量有明显的剖面分异性,随土层深度的增加而减小,且层间都具有显著性差异,不同坡位之间无明显差异,而在不同坡向之间表现为阴坡>半阴半阳坡>阳坡。随着生长年限增加,灌木林地土壤质量逐步得到改善。更多还原

【Abstract】 The wide planted shrub lands of soil and water conservation in Loess Plateau can prevent soil and water loss and have important effect on both revegetation and the ecological environment construction. This research aimed at the soil quality problem of shrub lands, took three kinds of shrub lands as research object as below: the Caragana Korshinskii Kom. Land （CKK） of Shanghuang experimental field in Gu yuan City, Ningxia Hui Autonomous Region,the Hippophae Rhamnoides L. land （HRL） of Gaoquangou watershed in Dingxi City, Gansu province and the Natural Secondary Forest land （NSF） of Feimahe watershed in Yan’an City, Shaanxi province. This thesis systematically researched the basic feature, the vertical and horizontal distribution, indicator system and comprehensive assessment of soil quality by soil sample collection, field investigation, laboratory analysis on soil physical, chemical and soil enzyme indicators, and statistic methods of variance analysis, correlation analysis, factor analysis and stepwise regression analysis. The main results were as follow:1. The change trend of sand and silt particle content of the three shrub lands on different slope aspect is shady slope>half sunny slope>sunny slope, and clay particle content is shady slope>half sunny slope>sunny slope; the difference of sand and silt particle content on different slope position is upper>middle>lower position of slope, and contrary sequence for clay particle content. The soil aggregate content on the upper position of slope>middle>lower position of slope, and it showed shady slope>sunny slope>half sunny slope on different slope aspect. The improve effect sequence of shrub lands on siol aggregate is HRL>CKK>NSF. Compare with 10 years old CKK, the 20 years old ones had less sand particle and more silt and clay content, this showed the soil has a little changed to fine soil. The total soil aggregate content, mean weight diameter and the soil aggregate content of different diameter all increased a little. The Bulk Density of shrub lands increased by the depth increase on the soil profile and the improve sequence is HRL>CKK>NSF.2. The content of organic matter （OM）, total N （TN）, alkali-hydrolyzed nitrogen （AHN）, available K（AK）, CEC, and CaCO₃ in the topsoil of shrub lands is mostly“middle”level except AHN of CKK and NSF is“lower”level, AK of NSF is“sub-high”level, CEC of CKK is“lower”level, CaCO₃ of CKK is“high”level. The total P （TP） content of CKK and HRL is“high”level and NSF is“sub-high”level; and the available P （AP） of three shrub lands is“much lower”level, at the same time, the total K of three shrub lands is“sub-high”level.The content of OM, CaCO₃、AK and EC of the topsoil of three shrub lands decreased by the increase of soil depth on the profile, and there are significant differences between the different soil layers. On the other hand, the content of TN, AHN and TK showed no significant difference on the profile.The OM and TN content of the topsoil showed same distribution regular pattern, that is upper<middle<lower position of slope for CKK and HRL, and contrary sequence for NSF. The TP and AP content increased from upper to middle and lower position of slope. The change trend of OM,TN,TP and AP content was shady slope>half sunny slope>sunny slope between different slope aspects, but AHN didn’t show the same trend. Meanwhile, the content of TK and AK showed no significant difference between both different slope positions and different slope aspects.Compare with 10 years old CKK, the 20 years old ones had less TP, AP, CaCO₃ and lower pH, but had more OM, TN, AHN, AK, CEC and EC. In a word, the soil nutrition contents and soil quality will improve with the increase of age of shrubs.3. The activity sequence of phosphatase and Invertase of the topsoil of three shrub lands is CKK>HRL>NSF, but it is CKK>NSF>HRL for urease. Slope aspects had no notability influence on soil enzyme activities but the slope positions obviously influenced the soil enzyme activities, the enzyme activities of the upper slope positions are generally higher than lower slope positions. The soil enzyme activities enhanced as the tree ages increasing and fell down as the depth of soil profile increasing.4. It showed very significant correlation between most of physical features of the researched 15 physical properties, and also for the researched 12 chemical properties except coarse clay particle, fine and Coarse silt particle and water content. The fine clay particle, fine silt particle, fine sand particle and OM had significant improvement on the nutrition conservation and soil quality enhancement. It showed very significant correlation between the soil enzyme （urease, phosphatase, Invertase） activities of three shrub lands.5. The simple assessing indicator system of 9 indicators for soil quality had been ascertained for the shrub lands on Loess Plateau: OM, TN, TP, TK, AHN, Invertase activities, CEC, CaCO₃ and water content. The assessing model had been established and was used to assess the soil quality of the three shrub lands. The result showed the soil quality sequence is HRL>CKK>NSF. The soil quality of HRL is gradeⅡ, but the quality of CKK and NSF is gradeⅢ. The best shrub type should be HRL when we plant shrub in Loess Plateau, the second should be CKK, and the last one should be NSF. The soil quality of the three shrub lands was obviously different on the soil profile, decreasing with the soil depth increase, and there were significant difference between different soil layers on the profile. The soil quality of different slope position had no significant difference, but that of different slope aspects was shady slope>half sunny slope>sunny slope. The soil quality improved with the increase of shrub ages.更多还原