【作者】 杨越；

【导师】 孙保平； 赵廷宁；

【作者基本信息】 北京林业大学 ， 工程绿化， 2010， 博士

【摘要】 宁夏盐池县是具有典型代表性的北方农牧交错区。近年来大范围的植被恢复对于遏制土地退化、改善生态环境产生了积极作用。植被恢复的过程对盐池县景观动态与生态系统产生较大影响,探讨其变化发展规律具有重要的生态学意义。本文采用遥感影像与地面调查相结合,运用现代“3S”技术与景观生态学原理,从宏观尺度对盐池县10年土地利用／覆被变化和景观动态变化进行分析；并采用野外试验与室内实验分析相结合的方法,运用恢复生态学、植物生态学、土壤学、水文学等相关理论,以退化生态系统区域尺度植被种类、群落结构、土壤质量、水分水文效应、风蚀防治效应等为切入点,系统研究盐池县不同植被恢复过程的生态效应,并建立生态效应评价指标体系,对不同植被恢复过程进行生态效应评价。主要研究结果如下：(1)盐池县植被恢复过程中土地利用／覆被发生较大变化。从1999～2009年以来不同时段中,农地一直呈现递减趋势,由占全县面积的21.78%减小到18.49%,减少22180.19 hm2；林地一直呈现增长趋势,从占全县面积的9.79%增加到13.08%,增加22179.6 hm2,其增长的来源均主要为草地,其次为农地；居民及建设用地从占全县面积的1.28%增加到4.20%,增加19708.12 hm2；未利用地在1999年以后开始大幅度减少,主要为流动沙地的减少,其减少的部分主要转化为林地和草地。(2)盐池县植被恢复过程中景观动态产生变化。类型水平上,不同时期土地利用Ⅰ级分类的平均斑块面积(MPS)排序是草地>农地>林地>未利用地>水域>居民建设用地,土地利用Ⅱ级分类中高盖度草地与低盖度草地的MPS随时段的变化幅度较大,其他类型的变化不明显；斑块面积变异系数(PSCV)变化总体上呈现减小的趋势,离散程度逐渐减小；各类型草地的最大斑块指数(LPI)明显高出其它类型,体现草地的基质作用；有林地的LPI在不断升高,而旱地和疏林地的LPI却在降低,表明生态建设取得良好成果。景观水平上,盐池县1999～2003年景观的破碎度加大,景观异质性增加,2003～2009年的景观破碎度降低,景观异质性减弱；最大斑块指数(LPI)和变异系数(PSCV)均呈较小幅度波动；不同时期景观的面积加权平均形状指数(AWMSI)和面积加权平均分维数(AWMPFD)的差异性较小,说明斑块形状的规则性及斑块边缘复杂程度变化较小。景观多样性(SHDI)、均匀度(SHEI)呈现细微波动,但整体平稳增长,表明近10年景观面积在不同类型之间的分配相对均匀,景观的异质性增加。聚集度(CONTAG)逐年下降和散布与并列指数(IJI)逐年上升的变化形成鲜明对比,说明景观中各种类型斑块在空间上的分布出现均衡化。(3)盐池县植被恢复过程的生态效应显著。植被恢复过程中,群落物种数量逐渐增加,物种丰富度逐渐提高,群落优势度指数、多样性指数也都比农地有所提高,群落生态效应明显。植物根系的穿插作用使土壤物理性质得以改善,土壤容重减小,孔隙度增加,土壤通透性提高,入渗性能增强；土壤颗粒组成也发生一定的改变,土壤团聚体含量,水稳性团聚体逐渐增加,土壤的抗蚀性逐渐增强。不同植被恢复过程对土壤养分状况有明显的改善,土壤有机质、全氮、全钾及有效氮、速效磷、速效钾含量变化明显。不同植被类型根系分布深度及密度的差异使土壤蒸发和植被蒸腾不同,因此土壤含水量之间存在明显的差异。植被冠层对降水的截留作用削弱了雨滴对土壤的溅蚀,不同植被恢复类型的截留作用表现各异。枯落物层是拦截降水的重要环节,研究中所选立地类型以灌木草本为主,枯落物层容水量相对较小。植被恢复对风速和下垫面性质产生一定影响,风蚀防治作用明显。植被恢复过程中植被物种群落特征,土壤物理化学性质、土壤水分、水文等生态因子之间是相互关联、相互作用的,不同生态因子间的相关程度不同。(4)盐池县不同植被恢复过程的生态效应指数均处在(0.4-0.6)之间,评价等级为中级。不同立地类型的生态效应指数(EEI)的大小排序为：天然草地>退耕还林地>人工封育草地>撂荒地>固定沙地>农地。植被恢复过程在群落效应、土壤物理效应、土壤化学效应、水文水分效应以及风蚀防治效应等方面产生了积极的影响,促进了盐池县生态环境的改善和土地荒漠化的逆转。因此,结合盐池县自然地理与社会经济等方面条件,因地制宜的推进植被恢复与生态建设是盐池县生态环境可持续发展的重要保障。更多还原

【Abstract】 Yanchi County of Ningxia Hui Autonomous Region is a typical Ecotone of Agriculture-animal Husbandry in northern part of china. For the past few years, the extensive vegetation restoration played an important role in preventing land degradation and improving the ecological environment. The process of vegetation restoration had a greater impact on landscape and ecosystems in Yanchi County. To study the regularity of its changes has important ecological significance. This paper, basing on remote sensing image and ground survey, used the modern "3S" technology and landscape ecology principles, analyzed 10 years of land use/cover changes and landscape dynamics of Yanchi County from the macroscale; and basing on Restoration Ecology, Plant Ecology, Soil Science, Hydrology and other related theories, used the method of field tests and laboratory experiment, researched the ecological effects of different vegetation restoration from the regional scale of vegetation types of ecosystems, community structure, soil quality, water hydrological effects, wind erosion control effects; and established the ecological effect evaluation index system, evaluated the ecological effect of the different vegetation restoration process. The major research results were as follows:(1) The land use/cover was changed greatly during the process of vegetation restoration in Yanchi County. From 1999 to 2009, in different periods, the agricultural land been showing decreased by the county total area of 21.78% to 18.49% reduction, reducing 22180.19 hm2;forestland had been showing increasing trend from the county total area of 9.79% to 13.08%, increasing 22179.6 hm2, the source of its growth was mainly grassland, followed by agricultural land; residential and industrial land had been showing increasing trend from the county total area of 1.28% to 4.20%, increasing 19708.12 hm2; unused land had been reducing significantly since 1999, mainly the floating sandy land reduction, which reduced some of the major converted to forestland and grassland.(2) The landscape dynamics was changed greatly during the process of vegetation restoration in Yanchi County. Type level, in different periods, the sequencing by the mean patch space (MPS) of the first level land use classification, was grassland> farmland> forestland> unused> waters> residential and industrial land, and the second level land use classification, the MPS of the high and low cover degree cover grassland changed obviously with the time, but the other types did not; the patch size coefficient of variation (PSCV) changes showed a decreasing trend in generally, degree of dispersion decreased; various types of grassland in the largest patch index (LPI) were significantly higher than other types, reflecting the matrix interaction of grassland; the LPI of Wood land was rising, while the LPI of dry land and sparse woodlot were reducing, which showed that ecological construction attained good results. Landscape level, the landscape fragmentation and heterogeneity increased from 1999 to 2003, while decreased from 2003 to 2009 in Yanchi County; largest patch index (LPI) and the patch size coefficient of variation (PSCV) showed a smaller range of fluctuation; the area weighted mean shape index (AWMSI) and area weighted mean fractal dimension (AWMPFD) had small differences among different periods, explaining the rules of patch shape and complexity of patch edge changed little. Landscape Diversity (SHDI) and evenness (SHEI) showed minor fluctuations, but overall steady growth, which showed that nearly 10 years in different types of landscape area were between the relatively uniform distribution, landscape heterogeneity increased. The contagion index (CONTAG) decreasing and Interspersion and Juxtaposition Index (IJI) increasing year by year changed in contrast, showed that various types of landscape patches appeared in the spatial distribution of equalization.(3) The ecological effects of the process of vegetation restoration were significant in Yanchi County. By the restoration process, number of species increased, species richness gradually increased, the community dominance index, diversity index had increased more than the agricultural land, community ecology effect was obvious. The plant communities with interspersed roots improved the soil physical properties, soil bulk density decreased, porosity increased, the permeability of the soil increased with infiltration performance enhancement; soil particle composition also occurred in some of the changes in soil aggregate content, water stable aggregates gradually increased the corrosion resistance of the soil gradually. Different vegetation restoration on soil nutrients had significantly improved, soil organic matter, total N, total K and available N, P and K contented significantly. Depth and density of root distribution among different vegetation types made the different soil evaporation and plant transpiration, therefore the soil water content existed significant differences. The role of interception to rainfall by Canopy of vegetation decreased and weakened splash on soil erosion, and different vegetation restoration displayed differently. Litter was an important part of interception to rainfall, because of the selected site type of herb to shrub, water capacity with the litter layer was relatively small. The different vegetation restoration process had influence on changing surface and wind speed, and played an important role in wind erosion controlling. Vegetation species, vegetation community characteristics, soil physical and chemical properties, soil moisture, hydrological and other ecological factors were interrelated and interactive, and between different ecological factors related to different degrees.(4) In Yanchi County, the ecological effects index of vegetation recovery was in (0.4-0.6), with evaluation of an intermediate. Different types of ecological effects index (EEI) with the size of the order: natural grassland> grain for green land> manually fencing grassland> abandoned land> fixed sand land> agricultural land. The vegetation restoration had a positive effect in the community, soil physical effects, soil chemistry effects, water effects wind erosion control and so on, promoted the ecological environment improvement and reversal of desertification in Yanchi County. Therefore, in Yanchi County combining with physical geography and socio-economic conditions to promote ecological construction is important protection for sustainable development of ecological environment.更多还原