民勤绿洲边缘粘土沙障生态水文效应研究

发布时间：2018-05-30 18:52

本文选题：粘土沙障 + 生物结皮　；参考：《中国林业科学研究院》2015年硕士论文

【摘要】：土壤结皮对土壤水文过程及植被生长分布的影响一直是学术界比较关注的话题。本文通过对不同年代土壤结皮的生态调查和天然、模拟降雨后土壤水分动态的连续监测,分析了不同发育阶段的土壤结皮对于土壤水文过程的影响,同时结合各样地内植被生长与分布现状,初步总结了民勤绿洲边缘粘土沙障土壤结皮影响生态水文过程及荒漠植被动态的规律及机理。初步结论如下:(1)近50年来,民勤绿洲边缘的年均降水量为115.6mm,月分配差异大,主要集中在6~9月份,占全年降水量的73.92%。近10年的日降雨量分布显示,0.1~5.0mm、5.0~10.0mm两个雨量级的降雨频度最高,分别占年降雨次数的81.9%、12.6%,≥10.0mm的降雨发生频率虽不足5%,降雨量占年均总降雨量的35.1%。从雨量雨强角度,民勤地区降雨分为大雨量小雨强和小雨量大雨强两种。(2)民勤绿洲边缘人工固沙植被区土壤结皮可分生物结皮和物理结皮,其中20世纪60年代初、60年代中、70年代形成的人工固沙植被区以生物结皮为主,90年代和21世纪10年代形成的人工固沙植被区为物理结皮,80年代介于中间。土壤结皮理化性质分析表明,结皮厚度、紧实度、粘粉粒含量、有机质、全氮的含量随固沙年限的增加而增加,容重却随固沙年限的增加而减小。(3)结皮层和2-10cm土层对降水拦截存在差异,其中结皮层对降雨的拦截量与固沙年限呈正相关关系(r=0.961),且结皮发育年限越长,对降雨拦截及其水分在土壤中的运动影响越大。2-10cm土层的降水截留量在生物结皮覆盖下随固沙年限的增加而减小,在物理结皮覆盖下结果相反。(4)28.4mm的天然降雨连续观测表明,随着固沙年限的增加,降雨入渗深度表现为1960s初1960s中1970s1980s1990s21st初;小雨强大雨量情况下,入渗深度基本随着结皮发育年限的增加而减少;大雨强小雨量情况下,入渗深度随结皮发育年限的增加而增加;各年代结皮对入渗的阻碍效果表现为60年代70年代80年代,阻碍作用随着降雨量的增加而减弱。(5)结皮对于土壤水分再分配的影响差异具有阶段性。土壤水分以入渗为主的阶段,0-10cm和10-20cm层土壤水分再分配随着固沙年限的增加而增加。入渗-蒸发阶段,0-10cm和10-20cm层水分差异减小。0-10cm层,以80年代为界,生物结皮土壤水分均随着固沙年限的增加而减少,物理结皮土壤水分均随着固沙年限的增加而增加。以蒸发为主的阶段,10-20cm层土壤水分高于0-10cm层,且两者的水分含量仍以80年代为界向两侧递减。(6)不同类型的结皮对蒸发的影响有很大差异。28.4mm降雨后,物理结皮对蒸发为单一的促进作用,生物结皮对蒸发则表现为先抑制后促进。土壤结皮蒸发的年代梯度仅表现在累计蒸发量上,其随着固沙年限的增加而增高。随着时间推移,各年代蒸发过程趋于减缓,但累计蒸发量的年代梯度差异变大,总体表现为生物结皮流沙物理结皮。(7)各年代梭梭的株高、地径、冠幅均随着固沙年限的增加而递增,新梢长度则随着固沙年限的增加而递减。梭梭的密度、盖度在80年代均出现了骤降,草本多样性却达到最高。其中单位面积物种数、植被盖度、多样性指数均表现为固定沙地植被(60年代、70年代)半流动半固定沙地植被(80年代、90年代、10年代)流动沙地植被,画眉草、黄花矶松、红砂等指示植物的出现再次佐证了土壤水分条件的变化。
[Abstract]:The influence of soil crust on soil hydrologic process and vegetation growth distribution has been a topic of concern in academic circles. In this paper, the influence of soil soil crust on soil hydrology process in different developmental stages is analyzed through the ecological investigation of soil crust in different ages and natural monitoring of soil moisture dynamics after rainfall. According to the present situation of vegetation growth and distribution in various fields, the law and mechanism of the ecological hydrological process and the dynamics of the desert vegetation on the edge of clay sand barrier in the Minqin oasis are preliminarily summarized. The preliminary conclusions are as follows: (1) in the last 50 years, the annual average precipitation at the edge of Minqin oasis is 115.6mm, and the monthly distribution difference is large, mainly in the month of 6~9. The daily rainfall distribution of the annual precipitation of 73.92%. in the last 10 years shows that the rainfall frequency of the two rainfall levels is the highest in 0.1~5.0mm and 5.0~10.0mm, accounting for 81.9% of the annual rainfall times, 12.6%, and more than 5% of the precipitation frequency of 10.0mm, which accounts for the 35.1%. of the annual total rainfall from the angle of rain and rain, and the rainfall in Minqin area is divided into heavy rainfall intensity. There are two kinds of heavy rain and heavy rain. (2) the soil crust can be divided into biological crust and physical crust in the artificial sand fixing vegetation area on the edge of Minqin oasis. In the early 1960s, in 60s, the artificial sand fixing vegetation areas in 70s are mainly biological crusts, and the artificial sand fixing vegetation areas in 90s and 2010s are the physical crust and 80s. In the middle. The analysis of soil physicochemical properties showed that the thickness of the crust, the compaction degree, the content of sticky powder, the content of organic matter and total nitrogen were increased with the increase of sand fixing years, but the bulk density decreased with the increase of fixed period of sand fixation. (3) there was a difference in precipitation interception between the nodal cortex and the 2-10cm soil layer. Positive correlation (r=0.961), and the longer the growth period of the crust, the greater the effect of rainfall interception and the movement of water in the soil, the precipitation interception in the.2-10cm soil layer decreases with the increase of sand fixation years, and the result is opposite under the physical crust coverage. (4) the continuous observation of natural rainfall in 28.4mm shows that with the year of sand fixation The depth of rainfall infiltration is at the beginning of 1970s1980s1990s21st in the initial 1960s of 1960s, and the infiltration depth decreases with the increase of the growth years of the crust when the rainfall is strong, and the infiltration depth is increased with the increase of the growth years of the crust under heavy rain and heavy rainfall; the hindrance effect of the crust infiltration in each age is 60. In 80s 70s, the hindrance was weakened with the increase of rainfall. (5) the effects of the crust on soil water redistribution were phased. The soil moisture redistribution in the 0-10cm and 10-20cm layers increased with the increase of sand fixing years. The water difference between the 0-10cm and 10-20cm layers in the infiltration and evaporation stage was in the stage of infiltration and evaporation. The soil moisture in the biological crust decreased with the increase of sand fixation years, and the soil moisture in physical crust increased with the increase of sand fixing years. The soil moisture in the 10-20cm layer was higher than that of the 0-10cm layer at the stage of evaporation, and the water content of the soil was still decreasing at the two sides in the period of 80s. (6) the difference between the soil moisture content of the soil crust soil and the 0-10cm layer decreased. (6) the difference between the soil moisture content and the soil moisture content of the two layers was decreased. There is a great difference in the effect of the type of crust on evaporation. After.28.4mm rainfall, the physical crust has a single promotion effect on evaporation, and the biological crusts show the first inhibition and then promote the evaporation. The time gradient of the soil crust evaporation is only shown on the cumulative evaporation, which increases with the increase of the fixed period of sand fixation. The growth process tends to slow down, but the age gradient of the cumulative evaporation becomes larger and the overall performance is the physical crust of the biological crustal flow sand. (7) the height of the plant, the ground diameter and the crown width in each age increase with the increase of sand fixing years, and the length of the new shoots decreases with the increase of sand fixing years. The density and coverage of the Haloxylon ammodendron have all dropped sharply in 80s. The diversity of herbaceous diversity was the highest, among which the number of unit area, the coverage of vegetation, and the diversity index were the vegetation of semi fixed sandy land (80s, 90s, 10s) in fixed sandy land vegetation (80s, 90s, 10s), and the appearance of soil water conditions again confirmed the appearance of soil water conditions by the appearance of thrush, pines, and red sand. Change.
【学位授予单位】：中国林业科学研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S154.4

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