Knowledge Resource Center for Ecological Environment in Arid Area
| 高时空分辨率额济纳绿洲植被动态变化分析 | |
| 其他题名 | Analysis of vegetation dynamic change in Ejina oasis with high spatial and temporal resolution |
| 李艺梦 | |
| 出版年 | 2016 |
| 学位类型 | 硕士 |
| 导师 | 祁元 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 绿洲地区天然降水少，是在一定的水源条件下，摆脱荒漠地区干旱气候大背景的制约形成和发育起来的干旱地区特有的隐域性景观，在荒漠区占据着生态系统结构的核心地位，承载着干旱区人类生存和繁衍的使命。绿洲作为荒漠区特有的地理景观，自然因素的多变性和人类活动的复杂性的耦合是驱动绿洲演替的基本机制，然而，绿洲对水资源的过度依赖造就了绿洲生态系统的极度脆弱性。额济纳绿洲作为阻止风沙进入黑河流域的第一道生态防线，不仅反映了当地的生态环境状况，更支撑着整个黑河流域社会经济的发展。但是过度的开发以及上中游不合理用水导致绿洲生态系统的退化，并伴随一系列的生态环境问题。因此，在2000年国家实行调水政策，通过黑河调水遏制绿洲的退化，本文从小尺度出发结合长时间序列的植被覆盖数据和高分辨率的土地覆被分类数据对额济纳绿洲调水前后绿洲植被动态变化进行分析，对绿洲的恢复和保护具有重要意义。植被覆盖度（Fractional Vegetation Cover，FVC）是描述生态系统的的重要参数，是植物群落覆盖地表状况的一个综合量化指标。土地覆被变化可以客观的反应人们对环境的改造，对促进经济、环境和生态的协调发展具有重要的现实意义。本文在RS和GIS技术支持下，以长时间序列的TM数据和高分辨率的SPOT影像为主要数据源，结合实地调查数据，研究了额济纳绿洲自调水前后十年的植被覆盖变化，对额济纳绿洲植被调水前后的的时空变化过程、特征、规律进行分析，论文的主要研究结论如下：（1）分析比较3类适用于干旱区域的植被覆盖度估算模型，其中像元二分模型法在额济纳绿洲区估算精度最高。（2）面向对象的分类方法能够有效提高高分辨率遥感影像的分类精度，针对额济纳绿洲景观破碎，异质性强的特点，采用面向对象分类方法获得下游精细土地覆被分类。（3）1990-2000年期间，绿洲植被以轻微退化为主要趋势。从河道横向分析，在距离河道500m距离河道越近，植被退化程度越低。从河道纵向分析，河道下游植被的退化最剧烈，中游其次，上游的植被退化最小。2000-2011年期间，绿洲以轻微改善为主要趋势。从河道横向分析，植被恢复与距离河道远近关系密切，离河道较近的植被恢复快，离河道远的地区植被恢复慢。从河道纵向分析河道中游植被的恢复最显著，上游其次，下游的植被变化最小。（4）从1990-2012年，研究区荒漠面积变化不大，呈现微弱上升的趋势；绿洲-荒漠过渡带的面积在2000年以前持续增加，2000之后逐渐减小，绿洲的面积在1990-2000年期间大幅度减小，在2000年之后逐渐增加，绿洲-荒漠过渡带和绿洲之间存在相互转化的关系。耕地面积的变化有一定的波动性，先大量增加后微弱减少。水体的面积先减少后增多；建筑用地的面积持续增长，且2004年以后建筑用地增长速度加快。（5）在1990-2000年期间，在人为因素作用下，耕地和建筑用地面积主要是以转入为主，耕地的转入面积最大；胡杨林主要向稀疏灌丛和耕地方向转移；稠密灌丛、稀疏灌丛和草地也大量向外转移；绿洲-荒漠过渡带和荒漠呈现增加的趋势，绿洲景观逐渐向绿洲-荒漠过渡带转变，荒漠化趋势明显。2000-2012年期间，耕地和建筑用地变化显著，大量的稀疏灌丛转化为耕地；胡杨林主要转化为稀疏灌丛；稠密灌丛有稀疏灌丛转化而来，面积增大；稀疏灌丛大量转出，面积变小。植被的变化趋势说明林草灌丛植被均呈现良性发展趋势，绿洲逐渐恢复。（6）将植被覆盖趋势变化图和土地覆被分类图叠加分析调水前后植被的变化，结果表明：在黑河分水前，额济纳植被整体呈现轻微退化趋势，轻微退化中最显著的胡杨，其次是稀疏灌丛、稠密灌丛和草地；在调水后植被以轻微改善为主要趋势，稠密灌丛的改善最明显，其次是稀疏灌丛和草地，胡杨部分的改善相对较弱。 |
| 英文摘要 | Oasis is invisi-bility of the landscape in the condition of less natural precipitation and a stable water source to get rid of arid climate background, which is the core position of ecological system and bears the mission of human survival and multiplication in arid area. Oasis, as a uinque geographical landscape, is coupled with complexity of natural variability and human activities which is the basic driving mechanism of oasis succession. However, oasis excessive reliance on water resource makes the oasis ecosystem have extremely vulnerable. Ejina Oasis as to stop the sand into the first line of the the Heihe Basin, not only reflects the situation of the locale ecological environment, more support for the development of the social economy of the whole of the Heihe River Basin. But eccessive exploitation and unreasonable use of water by the upper and middle people leads to the degeneration of the oasis ecosystem, accompanied by a series of ecological environment problems. Therefore in the 2000 National implements the transfer of water policy to containment oasis degradation. This article analysis the dynamic change of oasis vegetation from the samll scale based on long time series vegetation cover data and high resolution land cover, which has great significance for the restoration and protection of the oasis.The vegetation coverage (Fractional Vegetation Cover, FVC) is an important parameter for describing the ecological system, which is a comprehensive quantitative indicators of the status of plant communities cover the surface. Land cover change can objectively reflect the environmental transformation by people, which has important practical significance to promote economic, the coordinated development of ecological environment .This paper studies the change of vegetation of Ejina oasis since ten years before and after transferring water , based on the RS and GIS technology, with a long sequence of TM images and high resolution data as the main data sources, combined with field survey data, and analysis the spatial and temporal variaton process and rules of vegetation since transferring water. The main conclusions are as follows:(1)This paper analysis and compares the three types of vegetation coverage estimation model of applicable in arid areas, finding the Dimidiate Pixel Model Method in the highest accuracy in Ejina oasis.(2)Oriented object classification method can eddectively improve the accuracy of classification of high resolution remote sensing image, according to the characterisitcs of Ejina oasis landscape fragmengtation and heterogeneity, so using this method obtain the fine land cover classification. (3)During 1990-2000, oasis vegetation had a slight degradation as the main trend. Horizontal analysis from the river, the river was closer, the lower the degree of degradation of vegetation at a distance of 500m. Longitudinal analysis from the river, the river downstream of the vegetaiton degradation is the most severe, midstream secondly, upstream of the vegetaion degradation in minimum. During 2000-2011, oasis vegetation had a slight improvement as the main trend. Horizontal analysis from the river, Vegetation restoration had a close relationship with the distance from the river, and vegetation can quick recover close to the river. Longitudinal analysis from the river, the restoration of vegetation in the middle reches of the most significant, followed by the upstream and downstream of the vegetaion change is minimal.(4) During 1990-2012, the desert area of the study area changed little, showing a slight upward trend; The area of oasis- desrert ecotone continueed to increase in 2000 years ago and decreased gradually after 2000; The oasis area in the period 1990-2000 greatly reduced and gradually increased after 2000, the mutual transformation of the relation between oasis-desert ecotone and oasis. The change of cultivated land area had a certain volatility, weak reduction after the first significant increase. The area of the water first decreased and then increased. The area of construction land continued to grow, and the growth rate of construction land was accelerated after 2004.(5) During the period from 1990 to 2000, in the role of human factors, the cultivated land and constructon land is mainly transferred and the farmland transferred to the maximum. Populus euphratica forest mainly tansfer to sparse shrub and farmland direction. Dense shrub, spares shrub and grassland are also a large outward transfered. The oasis-desert transitional zone and desert showed increasing trend, and oasis landscape gradually transfered to the oasis-desert transitional zone, which showed desertification was evident. During 2000-2012, cultivated land and consturction land changed significantly, and a large number of sparse shrub was converted into cultivated land. Populus euphratica forest transformated for sparse shrub. Dense shrub is transformed by sparse shrub and the area increased. A large number of sparse transferred and the area decreased. The change trend of vegetation that grass shrub vegetation showed a good development trend, and oasis gradully restored.(6)The vegetation cover trends charts and land cover classification map overlying analysis the change of vegetation before and after transferring water. The reults showed: vegetation showed a slight degradation trends before transferring water, where Populus was the most significant during slight degradation, followed by sparse shrub, dense shrub and grass. There was a main trend of slight improvement arter transferring water, where dense shrub was the most obvious, followed by sparse shrub and garssland, and the improvement of Populus euphratica is relatively weak. |
| 中文关键词 | 额济纳绿洲 ; 植被覆盖度 ; 土地覆被分类 ; 调水政策 ; 面向对象分类 |
| 英文关键词 | Ejina Oasis vegetation coverage land cover classification watre transfer policy object oriented classification |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 地图学与地理信息系统 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287685 |
| 推荐引用方式 GB/T 7714 | 李艺梦. 高时空分辨率额济纳绿洲植被动态变化分析[D]. 中国科学院大学,2016. |
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