祁连山北坡高寒草地不同坡位土壤水分空间格局研究

发布时间：2018-02-08 16:24

本文关键词： 土壤水分空间异质性空间自相关性地统计学　出处：《西北师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：土壤水分是植被格局形成和演变的主要因素,无论在大尺度上还是在小尺度上,土壤水分在空间上均存在一定的空间异质性与空间自相关特征,这些空间异质性及自相关包含一些有用信息。坡位作为重要的地形因子,能够导致水热因子等一系列土壤特性的变化,从而改变能量平衡,对植被的空间格局产生重要影响。鉴于此,本文利用传统统计学、地统计学方法、Moran’s I系数以及空间自回归模型,研究了祁连山北坡不同坡位浅层剖面(0-30cm)土壤水分0-8米尺度内的空间异质性特征、自相关关系、空间自相关尺度等空间结构特征以及土壤水分的影响因子,结果如下:(1)研究区表层土壤含水量在1.07%-15.68%之间变化,上、中、下三个坡位土壤水分波动范围分别为2.24%-9.58%(上坡位),3.06%-10.99%(中坡位),1.75%-13.87%(下坡位);0-10cm土层土壤水分波动范围为1.07%-12.46%,10-20cm土层土壤水分波动范围为2.05%-14.13%,20-30 cm土层土壤水分波动范围为2.19%-15.68%。(2)祁连山北坡不同坡位浅层剖面(0-30cm)土壤水分均符合正态分布,各坡位、各层土壤水分均存在高度的空间异质性,其中74.07%-88.41%的空间异质性是由空间自相关引起的,主要体现在2.06-6.56m之间的尺度上;各坡位、各层土壤水分的空间变异函数均为非线性模型,反映了土壤水分资源空间分布的非均质性聚集分布特征,各坡位土壤水分均呈现出斑块状分布格局且存在数个互不重复的高值中心和低值区域。(3)在下坡位,土壤水分具有较好的空间连续性,中坡位与上坡位的破碎化程度较强。这是由于本研究区土壤蒸散发较为强烈,在下坡位西北针茅呈集群状分布,株丛较为密集,形成的密集草毡层和枯落物组成了有效的地表覆盖层,不仅减少了土壤水分的蒸发,而且改变了土壤水分的空间异质性格局。上坡位土壤水分破碎化程度较强,出现了数个低值区域和高值中心;且上坡位20-30cm层土壤水分空间异质性较强,主要是由于西北针茅的根系主要集中在20-30cm土层。(4)全局空间自相关分析表明:上坡位土壤水分的空间集聚特征较中坡位和下坡位更为明显,这可能是由西北针茅的生物学特性和对资源需求的差异引起的;局部空间自相关分析表明:各坡位土壤水分均存在显著的局部空间自相关性,在局部地区形成“高-高”和/或“低-低”的空间集群,并和“高-低”和/或“低-高”的空间孤立区相伴发生,即形成“斑块”和“孔隙”相间分布的水平镶嵌格局。(5)在上坡位,影响土壤水分的主要群落特征是草地群落的高度,对土壤水分有正的显著影响;在中坡位,盖度较高的斑块西北针茅分布较集中,其地下根系的密度也较高,对土壤水分的吸收利用程度也就越强,西北针茅盖度对土壤水分的影响呈极显著的负相关;而在下坡位,西北针茅盖度和群落高度对土壤水分有较为显著的影响。
[Abstract]:Soil moisture is the main factor in the formation and evolution of vegetation pattern. There are some spatial heterogeneity and spatial autocorrelation characteristics of soil moisture in large scale and small scale. These spatial heterogeneity and autocorrelation contain some useful information. Slope position, as an important terrain factor, can change a series of soil properties, such as hydrothermal factors, thus changing the energy balance. In view of this, we use traditional statistics, geostatistical method, Morans I coefficient and spatial autoregressive model. The spatial heterogeneity, autocorrelation, spatial autocorrelation, spatial autocorrelation and the influencing factors of soil moisture were studied. The results were as follows: (1) the surface soil moisture content in the study area varied between 1.07- 15.68%. The fluctuation range of soil water in the next three slopes is 2.24-9.58 (the upper slope is 3.06k- 10.99cm). (the middle slope is 1.75-13.87.The range of fluctuation of soil moisture is 1.07- 12.4610cm and 10-20cm.) the fluctuation range of soil moisture in the upper slope is 2.05-14.13C20-30 cm and the range is 2.19-15.68.2.) in the north of Qilian Mountains, the fluctuation range of soil moisture is 2.19-15.68.1. 2) in the north of Qilian Mountains, the range of fluctuation of soil moisture is 1.07 -12.46 ~ 10 ~ (-20) cm and the range is 2.05 ~ 14.13 ~ (30) cm ~ (-1). The soil moisture content of different slope positions is normal distribution. There is a high degree of spatial heterogeneity of soil water in every slope position and layer. 74.07-88.41% of the spatial heterogeneity is caused by spatial autocorrelation, which is mainly reflected in the scale of 2.06-6.56 m. The spatial variation function of soil moisture in each layer is a nonlinear model, which reflects the heterogeneity of the spatial distribution of soil water resources. Soil moisture in each slope showed patch distribution pattern, and there were several non-repeated high value centers and low value regions. In the downhill position, soil moisture had a good spatial continuity. The degree of fragmentation of middle slope and upper slope is stronger, which is due to the strong evapotranspiration of soil in the study area, the distribution of Stipa arundinacea in the northwestern part of the downhill is clustered, and the density of plant clusters. The dense grass felts and litter formed an effective surface covering layer, which not only reduced the evaporation of soil moisture, but also changed the spatial heterogeneity pattern of soil moisture. There were several low value regions and high value centers, and the spatial heterogeneity of soil moisture was strong in 20 ~ 30cm layer. The global spatial autocorrelation analysis showed that the spatial accumulation of soil water in upper slope was more obvious than that in middle slope and downhill. This may be caused by the difference in biological characteristics and resource requirements of Stipa chinensis, and the local spatial autocorrelation analysis shows that there is a significant local spatial autocorrelation between soil moisture in each slope. Forming "high-high" and / or "low-low" spatial clusters in local areas, accompanied by "high-low" and / or "low-high" spatial isolation, That is to say, the horizontal mosaic pattern of "patch" and "pore" distributes in the upper slope. The main community characteristics affecting soil moisture are the height of grassland community, which has a positive and significant effect on soil moisture, while in the middle slope, The density of root system is higher and the absorption and utilization degree of soil water is stronger in the patches with higher coverage. The effect of coverage on soil moisture is very significant negative correlation, but in the downhill position, the soil water absorption and utilization degree is higher, but in the downhill position, the soil moisture is negatively affected by the soil water coverage. The coverage and community height of Stipa arundinacea in Northwest China had a significant effect on soil moisture.
【学位授予单位】：西北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S152.7

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