不同植被类型对陡坡地土壤水分循环的影响

发布时间：2018-02-27 12:26

本文关键词： 黄土高原植被类型土壤水分循环 Hydrus模型　出处：《西北农林科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：黄土高原植被恢复的主要矛盾是植物耗水和土壤供水之间的矛盾,不同植被利用土壤水分的能力不同,会影响坡地土壤水分的贮存、运输和转化。尤其是对于坡地来讲,降雨既是维持植物生长的主要来源,又是土壤侵蚀的主要动力之一。如何根据天然降水条件,合理规划经营各种人工植被的布局,一直是黄土高原地区治理开发中需要研究解决的问题之一。本文以草地,沙棘(Hippophae rhamnoides)、油松(Pinus tabulaeformis)、侧柏(Platycladus orientalis)及其混交林为研究对象,以植物叶面积指数变化、土壤水分动态、产流产沙量和蒸散量差异为主要研究内容,并利用Hydrus模型模拟草地、沙棘林、油松林、侧柏林土壤水分循环过程,进一步对水量平衡各项进行定量分析。得出的主要结论如下:(1)生长季内,叶面积指数(LAI)呈现先增加,到达最大值时保持相对稳定,然后再减小的趋势。各植被类型LAI大小顺序大体呈现乔木混交林乔灌混交林乔木纯林灌木纯林草地。(2)土壤水分季节变化规律与当年降雨量的多少及季节分配有直接关系,年际间差异较大。草地的速变层和活跃层明显浅于林地,林地的速变层、活跃层和次活跃层的大致分布在0~70 cm,70~120 cm和120~200 cm处,植被覆盖土壤200 cm以下土层均属于相对稳定层。(3)不同植被类型径流系数的大小顺序为乔木林乔木混交林乔灌混交林灌木林草地,不同植被类型侵蚀模数大小顺序与径流系数大体一致,即径流量越大,泥沙量也越多。(4)利用Hydrus模拟四种植被土壤水循环过程,土壤含水量模拟值与实测值均方根误差(RMSE)均在0.015~0.063 cm3/cm3之间,模拟精度较高。对比四种植被水量平衡各分量发现,径流量受饱和导水率(KS)值大小的影响,顺序为侧柏林油松林沙棘林草地,说明草地在减少地表径流方面的作用优于其它三种林地;冠层截留与LAI大小相关,顺序为油松林沙棘林侧柏林草地;蒸散量大小顺序为沙棘林油松林侧柏林草地。蒸散量在水分支出项中占主导作用,因此在进行水土流失和荒漠化防治时,要综合各方面因素选择最适植被类型,防止产生生物利用型土壤干层。
[Abstract]:The main contradiction in vegetation restoration on the Loess Plateau is the contradiction between plant water consumption and soil water supply. Different vegetation has different ability to use soil water, which will affect the storage, transportation and transformation of soil moisture on sloping land, especially for sloping land. Rainfall is not only the main source of plant growth, but also one of the main driving forces of soil erosion. In this paper, grassland, Hippophae rhamnoidesus, Pinus tabulaeformisi, Platycladus orientalis) and their mixed forests were studied. The difference of sediment yield and evapotranspiration was used to simulate the soil water cycle in grassland, Hippophae rhamnoides forest, Pinus tabulaeformis forest and lateral Berlin with Hydrus model. The main conclusions are as follows: 1) during the growing season, the leaf area index (Lai) increased first, and remained relatively stable when the maximum value was reached. The order of LAI of different vegetation types showed that the seasonal variation of soil moisture was directly related to the rainfall and seasonal distribution in the pure forest and shrub pure forest of Arbor and shrub mixed with Arbor and Irrigation, and the order of LAI size of each vegetation type was similar to that of pure forest and grassland in Arbor and shrub mixed forest. The rapid change layer and active layer of grassland are obviously shallower than that of woodland, and the active layer and sub-active layer of forest land are roughly distributed in the area of 070 cm ~ (70) cm ~ (70) ~ (70) ~ (120) cm and 120 ~ (200) cm, respectively. The order of runoff coefficient of different vegetation types is Arbor, Arbor, Arbor, Arbor and Irrigation, shrubbery and grassland. The order of erosion modulus of different vegetation types is roughly consistent with the runoff coefficient, that is, the larger the runoff, the more sediment.) the Hydrus is used to simulate the soil water cycle process of four vegetation. The RMSE of soil moisture content was between 0.015 cm3/cm3 and 0.063 cm3/cm3, and the simulation accuracy was higher. Compared with each component of water balance of four vegetation, it was found that the runoff was affected by the value of saturated water conductivity (KS). The order is that the grassland of Hippophae rhamnoides forest in Pinus tabulaeformis forest is superior to the other three kinds of forest land in reducing surface runoff, and the canopy interception is related to the size of LAI, and the order is the forest side of Berlin grassland of Pinus tabulaeformis forest. The order of evapotranspiration is Berlin grassland of Pinus tabulaeformis forest in Hippophae rhamnoides forest. Evapotranspiration plays a leading role in water expenditure. Therefore, in the process of soil erosion and desertification control, the optimum vegetation type should be selected according to various factors. Prevent the formation of bioavailable dry soil layers.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S152.7

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