克里雅绿洲植被覆盖的空间特征与其环境因子分析

发布时间：2018-01-08 18:06

本文关键词：克里雅绿洲植被覆盖的空间特征与其环境因子分析　出处：《新疆大学》2017年硕士论文　论文类型：学位论文

【摘要】：水资源贯穿于干旱区一切矛盾的始终,高强度地水土资源开发下的水盐失衡已成为引起干旱区绿洲景观格局变化的关键因子,由此而引发的绿洲内部土壤次生盐渍化、外围土地荒漠化以及生物多样性降低等问题使得绿洲的生态环境更加脆弱,人水矛盾更加突出,绿洲的生态安全面临威胁。水盐作为最基本的生态环境因子,其在时间和空间上都呈现出一定的异质性,这种生境异质性由量变到质变综合作用于地表植被,使绿洲植被呈现出一定的空间特征。深入剖析现有水盐状况下绿洲植被的空间特征和影响其空间分异的环境因子的关系是解决绿洲稳定发展的关键科学问题。因此,本文选取对陆地生态系统变化最为敏感的指示性因子——植被覆盖度,借助遥感、GIS等一系列空间分析技术探究了现有水盐状况下克里雅绿洲1996年、2000年、2006年、2011年和2016年五个时期植被盖度的空间分布格局、空间分形结构、空间自相关性和时空变化特征,并从自然和人文两大子系统出发,选取水、土壤、地形、气候、土地利用和灌溉6个环境因子共11个变量剖析了这些环境因子与2016年的植被盖度之间的空间耦合关系,最后运用主成分分析和地理加权回归方法分析了影响植被覆盖空间分异的主导环境因子及各主导环境因子的空间异质性。研究结论如下:1.克里雅绿洲植被覆盖度总体上呈现出绿洲内部核心区域高于绿洲外围的分布格局,空间差异明显。五个时间段植被覆盖度的Moran I指数都在0.5以上,呈空间正相关,在空间上呈集聚的态势,空间集聚效应最强的是2000年,其次为2006年和1996年,2016年次之,2011年相较最弱。2.1996-2016年克里雅绿洲整体植被覆盖的空间形态由复杂到简单再到复杂,空间结构由不稳定到稳定再到不稳定,是一个动态变化过程;20年间绿洲植被覆盖整体呈增加的趋势,局部区域略有减少,其中增幅比较大的主要是农区,明显减少的主要是在建筑用地周边;各植被覆盖类型在格网中的面积占比变化总体呈现出各覆盖类型接壤的部位变化剧烈,“边缘效应”明显,而且有“中向高转、低向中转、极低向低转、非向极低转”的趋势。3.在影响克里雅绿洲植被覆盖空间分异的环境因子中,地下水埋深、地下水矿化度、距地表水体距离、地表温度、土壤盐分与植被覆盖度总体呈负相关,土壤含水量与其呈正相关,坡度对植被盖度影响不大,与坡向的分析结果显示,近乎所有植被覆盖类型都呈现出东、西坡平坡北坡南坡的趋势。距公路距离对植被覆盖度影响的范围有限,灌渠密度主要影响农区的植被盖度。4.植被覆盖度与各土层土壤盐基离子的Spearman秩相关分析结果显示,植被覆盖度与土壤含水量呈弱的正相关,相关性均不显著;与电导率和除HCO3-离子外的其它盐基离子呈负相关,其中在20-40cm土层与Cl-、SO42-、K+呈显著的负相关,在40-60cm土层与电导率和Na+离子呈显著的负相关,在60-80cm土层与Cl-和Na+离子呈显著的负相关,在80-100cm土层与Cl-离子呈显著的负相关;与土壤表层和20-40cm土层的HCO3-呈显著的正相关;与土壤pH呈正相关,但各土层相关性均不显著。说明克里雅绿洲土壤理化性质对植被的影响主要是盐分胁迫,尤其是20-60cm土层的硫酸盐、碳酸盐和氯化钠对植被的危害比较大。5.主成分分析结果显示温度、坡向、距公路的距离、距地表水的距离和地下水矿化度是影响植被覆盖空间分异的最重要的生态因子。地理加权回归结果显示,所有解释变量中对植被覆盖度影影响最大的是温度、灌溉—土壤水和温度—地下水盐分,而距公路距离、距地表水的距离和坡向与植被覆盖度之间的相关性比较低。
[Abstract]:Water resources throughout all contradictions in arid area has high strength, water and salt imbalance of soil and water resources development has become a key factor caused by the change of landscape pattern of oasis in arid area, which caused the oasis soil salinization, land desertification and peripheral biodiversity decreased, more fragile ecological environment of oasis water, people become more prominent, the oasis ecological security threats. Salt water ecological environment as the most basic factor, which in time and space are showing a certain degree of heterogeneity, the habitat heterogeneity from quantity change to qualitative change in the comprehensive effect of vegetation, the oasis vegetation shows the spatial characteristics of certain depth. Analysis of spatial characteristics of existing state of water and salt under the influence of oasis vegetation and environmental factors in the spatial differentiation is to solve the key scientific problems of oasis stability and development. Therefore, the Select on terrestrial ecosystem change is the most sensitive indicator factors, vegetation coverage, using remote sensing technology, explores the existing situation of water and salt in Keriya oasis 1996, 2000, 2006 and a series of spatial analysis of GIS, 2011 and 2016 five period of vegetation cover spatial distribution pattern, spatial structure, spatial autocorrelation and the temporal and spatial variation characteristics, and from the natural and cultural situation of two subsystems, selection of water, soil, topography, climate, land use and irrigation of 6 environmental factors were 11 variables analysis of the spatial coupling relationship between the environmental factors and vegetation coverage in 2016, the spatial heterogeneity of the dominant environmental factors and finally using principal component analysis and geography the weighted regression method to analyze the effect of vegetation spatial differentiation and the dominant environmental factors. The research conclusions are as follows: 1. the vegetation coverage in Keriya Oasis Showing the oasis distribution pattern within the core area is higher than the outside of oasis, obvious spatial differences. The five time period of vegetation coverage of the Moran I index is above 0.5, a positive correlation, a trend of agglomeration in space, spatial agglomeration effect is the strongest in 2000, followed by 2006 and 1996, followed by 2016 in 2011, the weakest.2.1996-2016 years in Keriya oasis vegetation cover whole space from complex to simple to complex spatial structure from instability to stability and instability, is a dynamic process; 20 oasis vegetation cover showed an overall increasing trend, the local area decreased slightly, the relatively large increase of the main is the agricultural area, significantly reduced is mainly used in the construction of the surrounding; each type of vegetation cover in the grid in the area of accounting for changes in general showing each cover type on the part of fluctuations, " The edge effect is obvious, and there are "high, low to transit, very low to low, non environmental factors to the very low" trend of.3. on the effect of vegetation coverage in Keriya oasis spatial variation in groundwater depth, groundwater salinity, water distance from the surface, the surface temperature of the overall. The soil salinity was negatively correlated with vegetation coverage, soil moisture content and was positively related to slope on the little vegetation cover, slope analysis results and show that almost all types of vegetation are showing a trend of East and west slope of the northern slope of the southern slope. The slope from the road distance range of vegetation coverage on the impact of limited irrigation the density of vegetation is mainly affected by vegetation coverage.4. in covering the Spearman rank correlation analysis results and the soil cation showed that vegetation coverage and soil water content showed a weak positive correlation, the correlation was not significant; and the conductivity and the removal of HC The other is negatively related to cation O3- ion, which in the 20-40cm layer and Cl-, SO42-, K+ showed a significant negative correlation, in the 40-60cm soil layer was significantly negatively correlated with electrical conductivity and Na+ ions in the 60-80cm soil layer was significantly negatively correlated with Cl- and Na+ ions in the 80-100cm soil layer had a significant negative correlation with Cl- ion; a significant positive correlation with soil 20-40cm and soil HCO3-; pH was positively correlated with soil, but the soil was not significantly correlated. The influence of physical and chemical properties of soil in Keriya oasis vegetation is mainly salt stress, especially 20-60cm soil carbonate and sulfate, sodium chloride damage to vegetation is relatively large.5. principal component analysis results showed that the temperature, slope, distance to road, away from the surface water and groundwater mineralization distance is the most important ecological factors affecting vegetation spatial differentiation. Geographically weighted regression results It is shown that the greatest influence on vegetation coverage is temperature, irrigation, soil water and temperature, and groundwater salinity. The correlation between distance from road, distance to surface water and slope direction and vegetation coverage is relatively low.

【学位授予单位】：新疆大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948

【参考文献】