【作者】 郭娜；

【导师】 彭培好；

【作者基本信息】 成都理工大学 ， 第四纪地质学， 2010， 硕士

【摘要】 植被覆盖度作为科学研究所必需的基础数据,为生态、水保、土壤、水利、植物等领域的定量研究结果提供基础数据,确保相关研究结果、模型理论更加科学可信;作为生态系统变化的重要标志,可为区域或全球性地表覆盖变化、景观分异等前沿问题的研究提供科学的指示作用;同时,作为第四纪地质学和第四纪环境学研究的重要参数,在次生地质灾害的监测与防治研究中具有显著的指导作用。珠峰自然保护区以保护青藏高原特有的高寒带自然生态为主,主要保护对象为极高山景观及喜马拉雅山脉南翼湿润山地森林生态系统和北翼的半干旱高原灌丛、草原生态系统,属于典型的生态脆弱区。所以,亟需探讨可以在该区域实行的有效的监测和管理途径。本文首先介绍了植被覆盖度的基本理论、研究现状和发展趋势,然后分析并讨论了测量植被覆盖度的方法。以珠峰自然保护区为研究区域,应用像元二分法模型,在RS和GIS技术支持下,提取出保护区1990年、2000年和2005年的植被覆盖度信息。并选取不同海拔带的5种关键生态系统类型作为具体研究对象,分别探讨常绿阔叶林、常绿针叶林、常绿灌丛、嵩草草甸和高山流石滩稀疏植被的覆盖度变化的时空过程和变化趋势,并对其时空分异的原因进行简要分析,得出以下结论:(1)常绿阔叶林全部分布在保护区的南坡,在1990~2000年间的变化以稳定为主,约占78.56%,植被退化区域共占10.53%,恢复区域共达到10.91%,恢复区域略大于退化区域。而2000~2005年期间,在以稳定为主的前提下,退化面积共占21.84%,恢复面积共占12.65%,退化区域明显大于恢复区域。主要是由于部分牧民为获得经济收入、造房和生活取暖而过度砍伐森林所致。(2)常绿针叶林同样全部分布在南坡,且在1990~2000年与2000~2005年之间的变化均以稳定为主。其中前十年的退化面积大于恢复面积,而在2000~2005年间,其植被覆盖情况发生了明显的好转,退化区域由之前的203.64km2减少到了64.78km2,恢复区域则由23.96km2增加到了94.42km2,且稳定区域面积由之前的312.06km2增加到了380.46km2。说明在保护区成立的前十年,部分人只顾经济效益,对森林进行过度砍伐,是造成常绿针叶林的大量退化的主要原因。而在2000~2005年之间,由于“天然林保护工程”以及退耕还林政策的实施,同时,当地政府也加大了管理力度并采取了一系列的禁伐措施,所以会出现植被覆盖度变化朝恢复的方向转化。(3)常绿灌丛在1990~2000年之间稳定区域在整个覆盖度变化中的百分比达到76.42%,处于主要地位,退化区域共占13.24%,恢复区域共占10.34%,退化区域大于恢复区域。2000~2005年之间,恢复区域所占百分比略有增加,由原来的10.34%增加到12.28%。说明该植被类型在前十年出现了一定程度的退化,2000年以后由于政府加强保护力度,实行一系列禁牧措施,使其出现了轻微恢复,但整体上看该植被类型的退化区域还是略大于恢复区域。在空间分布上,该植被类型则是在以稳定为主的前提下,南北坡的退化面积均大于恢复面积,且南坡退化程度大于北坡。(4)嵩草草甸无论是在1990年~2000年内,还是在2000~2005年内,其变化的稳定区域都占绝对优势,均达到80%以上。其中1990~2000年间退化总面积占8.92%,恢复总面积占9.52%。2000~2005年,退化总面积占8.77%,恢复总面积占10.68%,恢复面积均稍大于退化面积。嵩草草甸在珠峰自然保护区的南北坡均呈稳定——恢复格局,且恢复区域集中在北坡。以上数据说明该生态系统类型整体变化趋势稳定,保护良好。(5)高山流石滩稀疏植被在1990~2000年间的退化区域共占10.96%,恢复区域共占11.22%。在2000~2005年的退化区域共占10.09%,恢复区域共占10.61%,退化和恢复均保持在基本平衡的状态,恢复面积略大于退化面积。说明该生态系统人迹罕至,人为影响较小。在南北坡的变化趋势也是以稳定为主,伴随轻微恢复。其中,南坡退化区域和恢复区域大致相等,而在北坡的恢复区域则略大于退化区域。更多还原

【Abstract】 IIIVegetation coverage, necessary for scientific research, can provide basic data for quantitative study on ecology, water reserve, soil, water conservancy, plant, etc., making the research results and model theories more scientific and credible. As an important changing marker of ecosystem, it can offer scientific indication for the study of frontier problems, such as the change of regional or global surface coverage, landscape differentiation, and accelerate the development of study on natural environment. And, as the important parameter of the study on quaternary geology and quaternary environmentology, it takes a significant role in monitoring and prevention for secondary geological disasters.Qomolangma Nature Reserve mainly protect the unique alpine natural ecosystem of Tibetan Plateau, including the extremely alpine landscape, the humid mountain forest ecosystem and semiarid plateau shrub-grassland ecosystem in the south and north slope of Himalayas respectively. The eco-environment there is so fragile that it is desiderate to approach effective monitoring and managing methods for this area.This paper introduced the basic theories of vegetation coverage, its research progresses and the developing trends. Then we analyzed and discussed the methods of measuring vegetation model. We take the Qomolangma Nature Reserve as study area, based on the dimidiate pixel model, with the support of RS and GIS, the vegetation coverage information of this area in 1990, 2000 and 2005 is extracted through improved pixel dichotomy model. In this paper, five crucial ecosystems in different altitude are studied specifically. They are evergreen broad-leaved forest, evergreen coniferous forest, evergreen shrub, Kobresia meadow and alpine talus vegetation. By approaching the changing process and trend of their coverage with the change of time and space, we analyzed the reason of the differentiation. The study results are as follows:(1) All the evergreen broad-leaved forests were distributed in the south slope of the study area, and the changing of the area of evergreen broad-leaved forest between the year of 1990 and 2000 relied mainly on stability, which accounted for 78.56%, the vegetation degradation region accounted for 10.53%, and the recovery region, however, which is a little larger than the degradation one accounted for 78.56%. The year between 2000 and 2005 when the area was mainly on stability, however, the vegetation degradation region accounted for 21.84% comparing significantly with the recovery one for 12.65%. Some herdsmen’pursuit of economic interests, building and heating through deforestation may be the cause of vegetation degradation.(2) The evergreen coniferous forests also distribution in the southern slope, and the changing in this area relied mainly on stability between either 1990 and 2000 or 2000 and 2005. The area of degradation region is larger than of the recovery region during the first 10 years. The vegetation coverage improved significantly between 2000 and 2005, the degradation region reduced from the past 203.64km2 to 64.78km2, with the recovery region increasing from 23.96km2 to 94.42km2, what’s more, the stability region also increasing from the former 312.06km2 to 380.46km2. The data showed that some people did excessive chopping only for economic interests in the first 10 years, making the evergreen coniferous forests degenerated greatly. During the year between 2000 and 2005, however, the vegetation coverage changed to the recovery way because of the project of natural forests protected and the policy of conversion of cropland to forest. The government also carried some measures of chopping forbidden and increased the management power, which promoted the forests recovery.(3) The stable region of evergreen shrub which is the primary area in coverage changing reached 76.42% between 1990 and 2000, the vegetation recovery region accounted for 10.34%, and the degradation region, however, which is a little larger than the recovery one accounted for 13.24%. The recovery region increased appreciably from former 10.34% to 12.28% from 2000 to 2005. We can draw a conclusion that the vegetation types degenerated in a certain degree in the first 10 years, but it recovered slightly after 2000 because of the grazing forbidden measures and the stronger protection by the government, however, the area of degradation region was still a little larger than the recovery one as a whole. By the condition of the stability on spatial distribution, the area of degradation region both in the northern and southern slope was larger than which of the recovery region, and the southern condition was more serious than the north.(4) The stable region in the changing of kobresia meadow held advantage above 80% whatever between 1990 and 2000 or between 2000 and 2005. The area of degradation region accounted for 8.92%, comparing by the recovery region for 9.52% between 1990 and 2000. From 2000 to 2005, the area of degradation region accounted for 8.77%, which is a little smaller comparing by the recovery region for 10.68%. Kobresia meadow in Qomolangma Nature Reserve was a stable—recovery style in both slopes, the recovery region, especially, was in the northern slope by large. So the change of this ecosystem type was stable, and the system was protect well. (5) The degradation region of alpine talus vegetation accounted for 10.96% between 1990 and 2000, and the recovery region accounted for 11.22%. Between 2000 and 2005, the degradation region accounted for 10.09%, which was a little smaller than the recovery one for 10.61%。So we can draw a conclusion that it was hard for people to get in this ecosystem which was hardly influenced by human beings. The main changing on each slope was stable style, sometimes was slight recovery. The area of degradation region on southern slope was equal to the recovery region, and the recovery region was a little larger than degradation one on northern slope.更多还原