【作者】 白智娟；

【导师】 乌兰图雅；

【作者基本信息】 内蒙古师范大学 ， 自然地理学， 2008， 硕士

【摘要】 绿洲是在稳定的水源条件下,摆脱荒漠、半荒漠地区干旱气候大背景的制约,形成和发育起来的一种隐域性景观,它在区域经济发展中发挥着举足轻重的作用。然而,绿洲的生存和发展对水资源的绝对和单一的依赖性,注定了绿洲生态系统的脆弱性,水资源的减少或不合理利用很容易导致绿洲生态系统的退化(荒漠化),从而危及绿洲的稳定和生态、经济安全。额济纳绿洲地处极端干旱的内蒙古西部,是我国西北地区的生态屏障,由于近几十年来,上游的过度开发,至20世纪中后期,使绿洲的生态环境逐渐恶化,水资源短缺,植被衰退,绿洲萎缩,严重影响了地区农林牧业生产和其他产业的开发,成为地区经济可持续发展的障碍。植被覆盖度是一个十分重要的生态气候参数,是植物群落覆盖地表状况的一个综合量化指标。研究植被覆盖度的估算及其变化,对生态系统环境变化起重要作用,也对水文、生态、全球变化等领域都具有重要意义。本文以1990年、2000年、2006年TM/ETM的遥感影像数据为主要数据源,结合实地调查,采用遥感与GIS相结合、定量与定性相结合、景观生态学及传统的踏查等方法,重点研究了额济纳绿洲自调水以来的植被覆盖变化。研究表明:1、采用亚像元分解模型法计算植被覆盖度,模型精度检验结果表明,该模型基本满足研究工作精度要求,适合于绿洲植被覆盖变化研究。2、额济纳绿洲植被现状分析表明,低植被覆盖为绿洲主要植被覆盖类型,面积为4706.17km2,占研究区总面积的30.34%。其次为中植被覆盖和高植被覆盖,各占研究区总面积的1.87%和0.23%。3、2000-2006年植被覆盖动态变化分析表明,调水后额济纳绿洲植被覆盖度增加,其中无植被覆盖转移为低植被覆盖的面积最大,其转移面积为553.23km2,占2000年无植被覆盖总面积的5.14%。其次为低植被覆盖转移为中植被覆盖。4、绿洲调水前的1990年与2000年植被覆盖对比分析表明,自1990年额济纳绿洲植被覆盖度降低,植被退化严重,至2000年达到3个时期内的最差状态;自2000年黑河调水后额济纳绿洲植被有所好转,但2006年的植被覆盖度仍不及1990年的状况,表明其改善的速度仍不及退化的速度,这充分说明调水任务的艰巨、调水力度应加强及生态环境改善的滞后效应。5、研究表明,额济纳绿洲植被覆盖度增加,除了调水对额济纳绿洲植被变化具有重要影响以外,其它因子如气温、降水和生态移民、退耕还林还草、牲畜头数减少等也起到了不可忽视的作用。更多还原

【Abstract】 Oasis is invisi-bility of the landscape in the condition of a stable water source against the big background of climate control in desert and arid semi-desert region. It plays a decisive role in the regional economic development. However, the dependence of single and absolute water resources on survive and develop of oasis is doomed to the fragile ecosystems of oasis. The reducing or unreasonable use of water resources very easily leads to the degradation (desertification) of oasis ecosystem. Thus the stability of oasis and the security of ecological and economic are jeopardizing.Ejin Oasis is located in the western of Inner Mongolia which is extreme drought. It is the ecological barrier in the northwestern region of China. The shortage of water resources, vegetation decay and oasis shrinking seriously impact the production of regional agriculture, forestry and animal husbandry and the development of other industries due to the upriver excess development in recent decades, to the late 20th century, the deterioration of the ecological environment in oasis gradually. It becomes the obstacle of sustainable development of regional economic.Vegetation coverage is a very important eco-climatic parameter and is a comprehensive quantitative index of the status of plant communities covering the earth surface. Study the estimate and change of vegetation coverage play an important role in environmental change of ecosystems and are of great significance in the hydrology, ecology, global change and other fields. In this paper, the image data of TM / ETM in the year of 1990, 2000 and 2006 is used as the main data source combining field survey. The methods are including combining remote sensing and GIS, combining quantitative and qualitative, combination of landscape ecology and the traditional methods such as step research. The research is focus on the change of vegetation cover in Ejin oasis since transferring water. It shows that:1. Sub-pixel decomposition model is used to calculate vegetation coverage. The results of precision test of model show that the model basically meets the requirements of precision in research work and suit for researching the changes of vegetation cover in oasis.2.By analyzing vegetation status in quo of Ejin oasis, it shows that low vegetation cover is the main type of vegetation cover in oasis, an area of 4706.17 km2 accounting for 30.34% of the total area in study area. This is followed by middle vegetation cover and high vegetation cover, account for 1.87% and 0.23% of the total area in study area.3. It shows that vegetation coverage increased after transferring water in Ejin oasis through analyzing the dynamic changes of vegetation cover in 2000-2006. The largest transferring area is no vegetation cover transferring to the low vegetation cover, an area of 553.23 km2, accounting for 5.14% in a total area of no vegetation cover in 2000. This was followed by low vegetation cover transferring to middle vegetation cover.4. By comparative analysis of vegetation cover in 1990 and 2000 before transferring water in oasis, it shows that vegetation coverage decreased and vegetation degradated seriously since 1990 in Ejin oasis. It reached the worst state in 2000 in three times. After the water diversion of Heihe River vegetation had improved since 2000 in Ejin oasis. But the vegetation coverage in 2006 was not better than that in 1990. It indicates that the speed of improvement still not reach the speed of degradation. That fully shows the arduous task of transferring water and the lag effect in improving ecological environment. The intensity of transferring water should be strengthened.5. The study shows that vegetation coverage increased in Ejin Oasis. In addition that transferring water to Ejin oasis have a major impact on vegetation changes, other factors such as temperature, precipitation and ecological migrants, returning farmland to forest and grassland, reducing livestock etc. also played a non neglectable role.更多还原