【作者】 白一茹；

【导师】 汪有科；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2012， 博士

【摘要】 黄土丘陵区生态环境脆弱，植被生长受到影响，研究区域枣树生态经济林土壤性质的时空特征有助于促进该区域植被生态建设及水土资源高效利用。本文分析了枣树林土壤全氮、有机碳、饱和导水率、容重、土壤含水量等理化性质的时空变异特征，探讨保墒措施对土壤水、热过程和枣树生长的影响，以及枣林与其它植被土壤性质的分布特征和差异，得出以下主要结论：（1）枣林坡面土壤全氮、全磷、有机碳、电导率、饱和导水率、粘粒和砂粒含量表现为中等变异性。pH、粉粒含量、容重、总孔隙度、毛管孔隙度和饱和含水表现为弱变异性。坡位对枣林坡面土壤全氮、有机碳、pH、容重、总孔隙度、毛管孔隙度、饱和含水量、饱和导水率、粘粒、粉粒、砂粒含量有显著影响（P <0.01），而对全磷和电导率影响不显著。土壤性质的空间分布的半方差模型可以用指数和球形模型来描述，除饱和导水率和粉粒含量外，其它土壤性质均表现出中等空间依赖性。交叉验证表明坡面土壤性质测定值与模拟值差异较小，其克里格空间分布图能精确反映土壤性质空间分布规律。（2）枣林坡面的表层土壤水分的变异系数基本达到0.1以上，表现出中等变异性，随着土壤含水量的增加，变异系数表现出明显递减的趋势。通过累积概率函数、平均相对偏差和spearman秩相关系数等时间稳定性分析得出，30cm深度土壤含水量的时间稳定性比10cm深度下的好，可以选择研究区域的代表性测点来估计整个区域的平均土壤含水量。（3）秸秆和砾石覆盖具有保墒和调节温度的作用。秸秆覆盖量越高，保墒效果越好。秸秆覆盖处理的土壤温度日变化幅度小于不覆盖处理，秸秆覆盖能够调节耕层土壤温度，有利于作物生长发育。降雨过程中砾石覆盖处理下的土壤含水量随时间增加的速率明显高于秸秆覆盖处理，说明砾石覆盖比秸秆覆盖更有利于降雨的入渗。砾石覆盖和秸秆覆盖处理的枣果含水量、VC含量、总糖含量和可溶性固形物显著高于不覆盖处理，说明覆盖措施有利于红枣的生长发育。（4）植被类型对土壤性质有显著影响（P<0.01），全氮和有机碳的大小顺序为：谷子>苜蓿>枣树>柠条，全磷的顺序为：苜蓿>谷子>枣树>柠条。土壤pH值在垂直方向上随深度增加而增大，全氮和有机碳含量均随土层深度增加而逐渐减小，在垂直分布上表现出明显的表聚性特征。不同植被类型土壤粒径分布曲线变化幅度大，表现出明显的非均匀特性。土壤粒径分布的广义维数D(q)为典型反S型递减函数，多重分形谱α-(α)为不对称的上凸曲线。植被类型对土壤粘粒、粉粒、砂粒含量和粘粒域的分维数有极显著影响（P<0.01）。（5）不同植被类型的土壤含水量均呈现出明显的季节变化特征，其变化趋势与降雨量密切相关，前期降雨量与土壤平均含水量呈显著正相关（R2=0.6198，P<0.01）。谷子地的土壤水分最高，而变异系数最小，说明谷子地的土壤水分较充足且稳定。随着土层深度的增加，不同植被类型的土壤水分表现出先增加后降低的变化趋势。土壤表层0~40cm为土壤水分活跃层，40~160cm为主要的土壤水分利用层，160~200cm为土壤水分调节层。更多还原

【Abstract】 In the northern loess plateau of china, the growth of vegetation was seriously affectedbecause of the fragile ecological environment. Study on the temporal and spatialcharacteristics of soil properties in the jujube ecological economic forest will help to improvethe ecological construction and water-soil resources high-efficiency utilization. In this study,the temporal and spatial characteristics of soil total nitrogen, organic carbon, saturatedhydraulic conductivity, bulk density, and soil moisture were analyzed, the effects of mulchingtreatment on soil moisture, temperature and the growth of jujube tree were investigated, andthe distributions of soil properties between jujube tree and other different vegetation typeswere researched. The main conclusions of this study were as follows:（1）The soil total nitrogen, total phosphorus, organic carbon, electrical conductivity,saturated hydraulic conductivity, clay and sand content had moderate variability. The pH, siltcontent, bulk density, total porosity, capillary porosity and saturation moisture content hadlow variability. The effects of slope position on total nitrogen, organic carbon, pH, bulkdensity, total porosity, capillary porosity, saturation moisture content, saturated hydraulicconductivity, clay, silt and sand content were significant (P <0.01). The effects of slopeposition on total phosphorus and electrical conductivity were not significant. Thegeostatistical statistics results showed that the soil properties were defined by the exponentialor spherical models. The nugget to sill ratios indicated that all soil properties had moderatedependences except the saturated hydraulic conductivity and silt content. The results ofcross-validation showed that spatial prediction maps from ordinary kriging method accuratelyreflected the distribution of soil properties in the study slope.（2）The coefficients of variation of soil moisture were almost more than0.1withmoderate variability. As the increasing of soil moisture, coefficients of variation decreasedobviously. The time stability analysis was used to investigate the soil moisture by cumulativeprobability function, mean relative deviation and spearman rank correlation coefficient. Theresults showed that the soil moisture at30cm depth had higher time stability than at10cm.The soil moisture at representative measuring site could estimate the mean soil moisture ofthe region. （3）The straw and grave mulching could conserve soil moisture and regulatetemperature,. The impact of conserving moisture would be better as the increasing of strawmulching quantity. The daily changing rate of soil temperature on straw mulching treatmentwas less than the non-mulching treatmeat. The straw mulching could regulate the soiltemperature and favor the growth of plants. In the process of rainfall, the soil moisture on thegrave mulching treatment increased more rapidly than the straw mulching treatment, whichindicated that grave mulching benefit the rainfall infiltration greater than straw mulchingtreatment. The fruit water content, VCcontent, total sugar and soluble solid content on the strawand grave mulching treatment were significantly higher than the non-mulching treatmeat. Theresults showed that the mulching treatmeat was good for the growth and development ofjujube tree.（4）The soil properties were significantly influenced by vegetation types (P <0.01). Theorder of the soil total nitrogen and organic carbon on different vegetation types was millet>alfalfa> jujube> Caragana Korshinskii Kom. The order of the total phosphorus was alfalfa>millet> jujube> Caragana Korshinskii Kom. As the increasing of the soil depth, the pHshowed the increasing trend, and the soil total nitrogen and total phosphorus showed the downtrend with the surface-aggregated distribution. The soil particle size distribution of vegetationtypes in the study region showed heterogeneous distribution and had multifractal feature. Thegeneralized dimensions spectra q-D(q) were decreasing function with inverted S-lag pattern.The multifractal spectrum functions α-(α) were asymmetrical convex curve. The claycontents, silt contents, sand contents, and dimension of silt domain values were significantlyinfluenced by vegetation types (P <0.01).（5）The soil moisture on different vegetation types showed the obvious seasonalvariation, which was closely related with the precipitation. There was significantly positiverelationship between the average soil moisture and the preceding quantity of precipitation(R2=0.6198，P <0.01). The soil moisture was highest on millet land with the lowestcoefficient of variation, which indicated that there was sufficient and stable moisture on milletland. The soil moisture on different vegetation types increased firstly, and then decreased withthe increasing of the soil depth. The0~40cm layer was weak absorbing layer for the verticalchange of soil moisture, the40~160cm layer was absorbing layer, and the160~200cm layerwas regulating layer.更多还原