陇中黄土高原典型人工林土壤水文过程研究

发布时间：2017-12-31 00:41

本文关键词：陇中黄土高原典型人工林土壤水文过程研究　出处：《兰州大学》2016年博士论文　论文类型：学位论文

【摘要】：植被与水分的关系问题是生态水文学研究的核心问题,正因为如此,生态水文学一经提出便备受青睐,为干旱半干旱区以植被建设为主的生态恢复实践提供了理论基础。在水土流失十分严重的黄土高原地区,植被恢复与重建迫切需要我们深入研究植物生长与水分之间的相互关系。因此,本文以陇中黄土高原安家沟小流域为研究区,以该区主要的水土保持树种柠条、沙棘和油松为研究对象,紧紧围绕土壤水文过程开展研究。首先收集了研究区近30年的降雨资料,分析了多年平均降雨分布格局,研究了整个小流域的土壤物理性质及其土壤入渗过程;其次,建立了柠条、沙棘和油松的野外观测样地,对三种造林树种的土壤水文过程进行定位观测。基于实测数据,以生态水文学的理论与方法,研究了柠条、沙棘和油松的冠层降雨截留特征、冠层蒸腾及林下土壤蒸发过程,然后对比分析三种造林树种的土壤水文过程,以期为黄土高原生态重建中的适宜树种的选择提供理论依据。通过研究,主要结论如下:1.对安家沟小流域1981-2010的日降雨数据分析表明:生长季年均降雨量为:271.56 mm,年际变异系数为29.14%。降雨事件以≤5mm的降雨为主,占全年降雨事件的44.55%,≥10mm的降雨频率很低,但对年降雨的贡献大,占降雨总量的64.87%。0-10d间隔期(无降雨日)所占比例最大,为年无降水期的87.03%,㧐10d间隔期呈增加趋势。近30年来,≤5mm d-1的降雨呈下降趋势,而≥10mm d-1的降雨略有上升,年内总降雨日数与降雨量均呈下降趋势。2.研究区的土壤物理性质及土壤入渗特征均受地形特征和植被类型的影响而具有空间异质性。具体表现在:①阴坡的土壤有机质、总孔隙度、毛管孔隙度和非毛管孔隙度均大于阳坡;阴坡的土壤容重小于阳坡;从整体来看,土壤容重从坡顶到沟底表现出高-低-高的变化规律。总孔隙度、毛管孔隙度和非毛管孔隙度则呈现出低-高-低的变化规律;②安家沟流域阴坡的初始入渗率小于阳坡,而稳定入渗率和平均入渗率均大于阳坡;坡位对土壤水分入渗也有较大影响,具体表现为坡中坡上坡下坡顶沟底,这恰好与土壤容重在整个流域的分布相反。由此可见,除了坡度与坡向之外,土壤容也是土壤入渗的主要决定因子;③不同树种入渗过程有明显的差异性,针叶树种的入渗率大于灌木树种。初始入渗速率、稳定入渗率、平均入渗率及60min累计入渗量的大小依次为:柠条沙棘油松。植被分布对土壤入渗过程的影响仅限于0-40cm的浅层土壤,对于60cm以下的深层土壤入渗影响不显著。3.基于安家沟小流域三种植被类型(柠条、沙棘和油松)下的土壤入渗实测数据,采用kostiakov公式、horton模型和philip模型进行入渗过程拟合,结果发现,horton模型对油松林下的土壤入渗过程模拟精度最好,相关系数可达0.92,但对柠条和沙棘林下的土壤入渗模拟效果差;kostiakov公式则能较好的模拟油松和柠条林下的入渗过程,但是对沙棘林下的入渗模拟精度不高;philip模型则对柠条、沙棘和油松的三种林下的土壤入渗模拟精度都比较高,因此,philip模型适合于安家沟小流域土壤入渗过程模拟。4.研究期间柠条、沙棘和油松的林冠截留率分别为28%、18.3%和22.4%,树干茎流率分别为12.3%、8.4%和1.1%。灌木树种的树干茎流率大于针叶树种油松的树干茎流率。三种林分下穿透雨的变异系数均随降雨量的增大而减小。采用gash解析模型对三种人工林的冠截留模拟结果表明:柠条、沙棘和油松的冠层截留量的模拟值均低于实测值。由于gash模型涉及的参数较多,因此,模型参数的估算的准确性决定了冠层截留量的模拟精度。本研究以油松冠层截留模拟为例,做了模型参数敏感性分析,结果表明冠层持水能力s对模型有较大的敏感性,其次,林冠盖度c及平均蒸发速率e也是影响冠层截留模拟的重要因子。5.油松在单株和样方尺度上穿透雨具有相似的空间变异性,即穿透雨的空间异质性随着降雨量的增大而降低。在降雨量较小时,冠层结构是穿透雨的主要影响因子,而当降雨量较大时,测量误差与其它非空间因素是影响穿透雨空间分布的主要因子。油松冠层边缘对穿透雨具有汇聚作用。树木的冠层结构是促使边缘效应发生的主要因素。6.采用热脉冲技术观测了灌木树种柠条、沙棘和油松单株的树干液流量,基于单株蒸腾观测的液流量,通过尺度上推(灌木林尺度上推的空间纯量为叶面积指数,乔木的空间纯量为边才面积)获得了2013与2014年两个生长季林分尺度的日蒸腾量。其中,2013年油松、沙棘和柠条的蒸腾量分别为:305.09mm、243.17mm和203.4mm;2014油松、沙棘和柠条的蒸腾量分别为:251.24mm、220.02mm和189.35mm,由于2013年较2014年高温多雨,2013年三种林分的蒸腾量均大于2014年。三种林分相比较而言,乔木的蒸腾量大于灌木,其中灌木林中,沙棘的蒸腾量大于柠条。树木蒸腾量的变化主要受环境因子的影响,当土壤水分充足时,气象因子中太阳辐射和饱和水汽压差是主要影响因子,当土壤水分胁迫时,蒸腾主要受土壤水分的影响。柠条、沙棘与油松生态系统的土壤水量平衡分析表明,灌木树种的蒸散耗水量小于油松,其中柠条蒸散的耗水量小于沙棘,三种造林树种中,柠条具有更好的水土保持功能。
[Abstract]:The problem of relationship between vegetation and water is the core problem of eco hydrology, because of this, the eco hydrology was proposed favored, provides a theoretical basis for ecology in arid and semi arid area in the construction of vegetation restoration practice. Soil erosion is very serious in the Loess Plateau, vegetation restoration and reconstruction of the urgent need for our further study on the relationship between plant growth and soil moisture. Therefore, taking the Loess Plateau in Gansu Anjiagou watershed as the study area, the main area of soil and water conservation species Caragana, sea buckthorn and Pinus tabulaeformis as research object, focus on the research of soil hydrological processes. The first collection of nearly 30 years of rainfall data in the study area. Analysis of the distribution pattern of the average rainfall years, soil physical properties and soil infiltration process of the small watershed; secondly, the establishment of sea buckthorn Caragana, Pinus tabulaeformis and field view Test plots, soil hydrological processes of the three tree species were observed. Based on the measured data, the theory and method of eco hydrology, Caragana, canopy rainfall interception characteristics of sea buckthorn and Pinus tabulaeformis, canopy transpiration and soil evaporation of forest, and soil hydrological processes of the three tree species comparative analysis. In order to provide theoretical basis for suitable species ecological reconstruction in the Loess Plateau selection. Through the research, the main conclusions are as follows: 1. in Anjiagou catchment 1981-2010 daily rainfall data analysis shows that the growing season average annual rainfall is 271.56 mm, the interannual variation coefficient was less than 5mm in 29.14%. rainfall event rainfall, annual rainfall accounted for the 44.55% events, the rainfall frequency is greater than or equal to 10mm is very low, but the contribution of annual rainfall, rainfall accounted for 64.87%.0-10d of the total interval (no rain) is the largest proportion, for the period of 87.03% years without precipitation, ? 10d interval increased. Over the past 30 years, more than 5mm of D-1 rainfall decreased, while D-1 increased slightly more than 10mm years of total rainfall, rain days and rainfall decreased.2. in the study area soil physical properties and soil infiltration characteristics were affected by topography and vegetation types due to spatial heterogeneity. Specific performance in the shady slope soil organic matter, total porosity, capillary porosity and non capillary porosity were higher than that of sunny slope; soil bulk density was lower than that of sunny slope; on the whole, the soil bulk density showed a high - low - high variation from the top to the ditch. The total porosity, capillary porosity and non capillary porosity showed a low high low variation; the initial installation gully in shady slope infiltration rate lower than that of sunny slope, and the stable infiltration rate and average infiltration rate were higher than that of sunny slope; slope position on soil water infiltration also affected Specifically, uphill downhill slope in slope top ditch, which coincided with the soil bulk density distribution in the whole basin instead. Thus, in addition to slope gradient and slope direction, the main factor determining the capacity of soil and soil infiltration; the infiltration process of different species have obvious differences, the infiltration rate is higher than coniferous trees shrub species. The initial infiltration rate, stable infiltration rate, average infiltration rate and cumulative infiltration of the 60min size is as follows: Caragana Seabuckthorn Pinus tabulaeformis in shallow soil. Only 0-40cm distribution of vegetation effect on soil infiltration, the deep soil below 60cm infiltration did not significantly affect the Anjiagou small.3. the three is based on watershed planting types (Caragana, sea buckthorn and Pinus tabulaeformis) the soil infiltration measured data, using the Kostiakov formula, Horton model and Philip model of infiltration process fitting, results show that the Horton model of Pinus tabulaeformis forest under soil infiltration The best process simulation accuracy, the correlation coefficient was 0.92, but the c.korshinsk forest soil infiltration simulation effect; Kostiakov formula can better simulate the infiltration process of Pinus tabulaeformis and Caragana korshinskii, but of seabuckthorn forest infiltration under the simulation accuracy is not high; the Philip model of Caragana, three forest sea buckthorn and Pinus tabulaeformis under the soil infiltration simulation precision is high, therefore, the Philip model is suitable for Anjiagou watershed soil infiltration.4. simulation during the process of Hippophae rhamnoides and Caragana korshinskii, Pinus tabulaeformis forest canopy interception rate were 28%, 18.3% and 22.4%, stemflow were 12.3%, stemflow stemflow 8.4% 1.1%. and shrub species than coniferous tree species of Pinus tabulaeformis. The coefficient of variation of throughfall in three plantations were decreased with the increase of rainfall. By using gash analytical model of three kinds of artificial forest canopy interception simulation results showed that Caragana, sea buckthorn Canopy interception of Pinus tabulaeformis and the simulated values were lower than the measured value. Because of the many parameters involved in gash model so that the simulation precision accuracy of estimating model parameters determines the canopy interception. In this study, pine canopy interception simulation as an example, the model parameter sensitivity analysis results show that canopy water holding capacity of s have great sensitivity to model secondly, canopy cover C and the average rate of evaporation is an important factor affecting e canopy interception simulation in a single.5. of Pinus tabulaeformis and quadrat scale spatial variability of throughfall is similar, the throughfall spatial heterogeneity decreased. With the increase of rainfall in the low rainfall, canopy structure is the main influencing factor of throughfall, when the rainfall is bigger, the measurement error and other non spatial factors are the main factors of throughfall spatial distribution of Pinus tabulaeformis canopy throughfall on edge. With the convergence effect. The canopy structure of trees is the main factors contributing to the occurrence of.6. edge effect by the heat pulse observation of shrub species of Caragana, the sap flow of seabuckthorn and Pinus tabulaeformis plants, plant transpiration fluid flow based on the observation, by scaling (Bush scaling space scalar for leaf area index, tree the amount of space for pure edge area) to obtain evapotranspiration in 2013 and 2014 two quarter growth forest scale. Among them, the 2013 transpiration of Pinus tabulaeformis, Hippophae rhamnoides and Caragana korshinskii were: 305.09mm, 243.17mm and 203.4mm; 2014 Pinus tabulaeformis, transpiration of Hippophae rhamnoides and Caragana korshinskii were: 251.24mm, 220.02mm and 189.35mm. As of 2013 2014 compared with the high temperature and rainfall, evapotranspiration in 2013 three stands were higher than 2014. Three stands in comparison, transpiration of trees is larger than the shrubs, bushes, transpiration of sea buckthorn than Caragana tree. Influence of wood transpiration is mainly affected by environmental factors, when soil moisture is sufficient, solar radiation pressure and meteorological factors and saturated vapor is the main influencing factor, when the soil water stress, the transpiration effect is mainly affected by soil moisture. The soil water balance of sea buckthorn Caragana, and Pinus tabulaeformis ecosystem analysis showed that evapotranspiration of shrub species the water consumption is less than the evapotranspiration of Caragana Pinus tabulaeformis, the water consumption is less than three of sea buckthorn, afforestation, soil and water conservation function of Caragana has better.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714

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