【作者】 马飞；

【导师】 彭培好；

【作者基本信息】 成都理工大学 ， 自然地理学， 2011， 硕士

【摘要】 本研究依托“中国-比利时”国际科技合作项目“西藏自然与文化遗产资源信息系统”(2008-2009,2008DFA11020),主要采用由搭载于EOS/Terra卫星上的中分辨率成像光谱仪(MODIS)获取并经过后期处理的250m分辨率归一化植被指数(NDVI)16日(d)合成数据(MOD13Q1)完成了珠峰自然保护区植被覆盖变化及沼泽湿地潜在退化风险评价。首先,利用2000～2009年10年的MODIS NDVI数据,基于每个像元的生长季NDVI峰值进行了像元水平的线性趋势分析,并参照珠峰地区自然区划图中南北坡区划,对珠穆朗玛峰自然保护区南坡和北坡的植被覆盖的空间分布和变化特征进行了研究。结果表明,(1)保护区内植被覆盖显著改善区域和轻微改善区域NDVI-Max的年平均增加率分别为3.06%和1.25%;显著退化区域和轻微退化区域NDVI-Max的年平均减少率分别为2.82%和1.09%。(2)2000～2009年,保护区南坡的植被覆盖整体上呈现上升趋势,22.59%的区域显著改善,19.05%的区域轻微改善,24.75%的区域保持稳定;北坡的植被覆盖整体上呈现下降趋势,19.5%的区域严重退化,24.43%的区域轻微退化,38.12%的区域保持稳定。(3)南坡有植被覆盖的8种土地利用类型中,山区旱地植被覆盖呈现退化趋势,其余土地利用类型都呈现上升趋势;北坡有植被覆盖的10种土地利用类型中,植被覆盖都呈现退化趋势。另外,选取珠峰自然保护区2009年全年23幅MODIS NDVI影像,采用基于傅立叶变换的HANTS算法去除云干扰并重构NDVI时间序列图像。根据研究区沼泽湿地与其它地物类型物候特征的差异,利用光谱角制图方法(SAM)获取了研究区2009年沼泽湿地的分布数据。研究区沼泽湿地共有2481.13km~2,占全区面积的6.88%;其中定日县分布最多,占沼泽湿地总面积的36.85%;其次为定结县、聂拉木县和吉隆县,分别占25.79%、24.5%和12.86%。针对研究区的特点,选用年平均气温的线性变化趋势为自然风险因子,基于距离衰减理论的居民点和道路影响为人为风险因子,对研究区沼泽湿地进行退化潜在风险评价,可划分为低风险、较低风险、一般风险、较高风险、高风险五个级别,各风险级别沼泽湿地面积占沼泽湿地总面积的比例分别为7.39%、13.61%、24.72%、31.43%、22.84%。更多还原

【Abstract】 The Qomolangma National Nature Reserve was established on 18 March 1989, On March 2005, it was listed in the global biosphere protected area network. The domestic studies on its vegetation cover change are less,and marsh wetland is very important to the environment of this region.Based on the project that the international scientific and technological cooperation project between China and Belgium that The Nature and Cultural Heritage Resources Information System in Tibet (2008-2009, 2008DFA11020) , this paper accomplished two aspects of research. On the one hand, using MODIS NDVI data from 2000 to 2009, the spatial distribution and variation of vegetation cover on the south slope and the north slope in the Mt. Qomolangma Nature Reserve were studied based on the linear trend analysis on the growing season NDVI peak value of each pixel by pixel level. The results showed that: (1) For significantly improved area and slightly improved area of vegetation cover, average annual growth rates of NDVI-Max are 3.06% and 1.25% respectively; For significantly degraded area and slightly degraded area of vegetation cover, average annual reduction rates of NDVI-Max are 2.82% and 1.09% respectively. (2)The vegetation cover of the south slope of the Mt. Qomolangma Nature Reserve showed an increasing trend on the whole from 2000 to 2009, and 22.59% of research area improved greatly, 19.05% improved lightly, 24.75% kept stable; while in the north slope, the vegetation cover showed a decreasing trend on the whole, and 19.5% of research area degenerated greatly, 24.43% degenerated lightly, 38.12% kept stable; (3) Among the eight landuse types covered with vegetation in the south slope, the vegetation cover of dry farmland in mountain area showed a decreasing trend, and the others showed an increasing trend; while within the ten landuse types covered with vegetation in the north slope, all of the vegetation cover showed a decreasing trend.On the other hand, taking the Mt. Qomolangma National Nature Reserve as the study area, selecting all 23 MODIS NDVI images of 2009, using the HANTS algorithm based on Fourier transform to remove the interference of the cloud and reconstruct NDVI time series images. The Spectral angle mapper(SAM) was used to extract marsh wetland of the study area according to the different phenological characters between marsh wetland and other surface features. The area of marsh wetland is 2481.13km2, which account for 6.88% of total study area; Its distribution in Tingri was the most abundant, which account for 36.85% of the total marsh wetland area; followed by Dingjie, Nyalam and Geelong, the propotions are 25.79%, 24.5% and 12.86% respectively. According to the characteristics of the study area, we evaluated the potential degradation risk of marsh wetland in the study area by selecting annual mean temperature linear trend as natural risk factor, influences of settlements and roads as artificial risk factors which are based on distance decay theory. This paper divided general risk assessed results mainly into five grades, that is, the lowest risk, lower risk, moderate risk, higher risk, and the highest risk, the proportions of the total marsh wetland area in the study area are 7.39%, 13.61%, 24.72%, 31.43% and 22.84% respectively.更多还原