塔里木河下游生态输水后植被景观格局动态变化研究

2000-2005年, 塔里木河流域管理局先后7次向塔里木河下游断流区进行了生态输水, 输水河道两岸的植被得到了一定的恢复. 以2000-2005的中巴资源卫星CCD影像为主要数据源, 获得了6 a的植被/非植被二值图, 并计算各年的景观格局指数, 分析了6 a植被景观格局的变化. 结果表明: 植被景观动态度在第四时段(2003-2004年)最大, 为47.83%; 在第三时段(2002-2003年)最小, 为-1.39%; 2000-2005年植被景观的动态变化呈正向趋势. 2000-2005年, 植被景观斑块个数与景观形状指数增加, 蔓延度指数下降了36.9, 斑块结合度指数均高于99, 表明研究区的植被景观破碎化程度、分离程度增加, 而景观类型联通性较高. 植被斑块面积均处于增加趋势且远离河道植被恢复率越小, 但植被景观的比重仍小于50%, 说明非植被类型是研究区的基质类型, 组成了景观的最大斑块. 针对缓冲区Zone 1, 植被景观的平均分维数处于减小趋势且2005年的斑块个数最小, 斑块结合度指数处于增加趋势, 表明近河道区域植被较为稳定, 受生态输水的干扰度较小, 植被景观斑块之间越来越聚集. 6 a间Zone 1的植被最大斑块指数均大于10%, 远高于其它5个缓冲带, 表明离河道越近植被景观的优势度最大.     

Desert riparian forest colonization in the lower reaches of Tarim River based on remote sensing analysis

The ecological water conveyance project that pipes water from Daxihaizi reservoir to lower reaches of Tarim River has been implemented ten times since 2000. After ecological water conveyance, restoration has taken place for vegetation along the dried-up lower reaches of the Tarim River. The changes of vegetation fluctuated yearly due to ecological water conveyance. In order to reveal the detailed process of vegetation changes, remote sensing images from 1999 to 2010 were all classified individually into vegetated and non-vegetated areas using the soil-adjusted vegetation index threshold method. Then inter-annual changes of vegetation over a period of 12 years were obtained using a post-classification change detection technique. Finally, spatial–temporal changes distribution of vegetation cover and its response to ecological water conveyance were analyzed. The results indicate: (1) vegetation area increased by 8.52 % overall after ecological water conveyance. Vegetation between 2003 and 2004 increased dramatically with 45.87 % while vegetation between 2002 and 2003 decreased dramatically with 17.83 %. (2) Vegetation area gain is greater than vegetation loss during 1999–2000, 2001–2002, 2003–2004 and 2009–2010 periods. Although vegetation restoration is obvious from 1999 to 2010, vegetation loss also existed except for the periods above. It indicates that vegetation restoration fluctuated due to ecological water conveyance. (3) Spatial distribution of vegetation restoration presented “strip” distribution along the river and group shaper in the lower terrain area, while spatial distribution of vegetation loss mainly located in the upper reaches of river and area far away from the river. (4) Vegetation restoration area had a positive relative with total ecological water conveyance volume. The scheme and season of ecological water conveyance had also influenced the vegetation restoration. The vegetation change process monitoring, based on continuous remote sensing data, can provide the spatial–temporal distribution of vegetation cover in a large-scale area and scientific evidences for implementing ecological water conveyance in the lower Tarim River.     

基于变化轨迹探测的植被景观格局动态分析——以塔里木河下游生态输水区域为例

 在遥感与GIS技术支持下,以2006、2007、2009、2010年Landsat-5/TM影像与2008年的CBERS/CCD影像为主要数据源,获得5 a的植被/非植被类型图。在此基础上,提取并归纳5 a间的植被变化轨迹:恒定植被、恒定非植被、转变为植被、转变为非植被、非稳定变化。利用景观格局分析软件FRAGSTATS 3.3计算了变化轨迹景观格局的3种景观指标。结果表明,2006—2010年植被面积减小,主要因为生态输水量减小、输水间隔较大,导致草本植被、乔灌木幼苗死亡;恒定非植被的比重最大,表明非植被类型是研究区的基质,其次是转变为非植被的比重,说明5 a间植被的衰退程度要强于恢复程度;转变为植被与非稳定变化两种类型属于过渡性植被变化类型,受生态输水量、分布的制约严重;各种变化轨迹类型的形状规则较为稳定,其中以恒定非植被类型最稳定而非稳定变化类型最不稳定。     

试论中国荒漠区人工绿洲生态系统的形成演变和可持续发展

绿洲是干旱区特有的生态系统，尤其是通过灌溉发展起来的人工绿洲，成为干旱区人类生存和繁衍的基地，它是由山地、绿洲和荒漠构成的干旱区三大生态系统的核心，发展绿洲是遏制土地沙漠化的重要措施。我国西北干旱区的绿洲形成，经历了三个时期：受到人类轻微干扰的自然水系时期，很多古代绿洲多分布在河流下游；受到人类较强干扰的半人工水系时期，在山前地带形成旧绿洲，下游古代绿洲衰亡；受到人类强烈干扰的人工水系时期，新扩大的绿洲多在旧绿洲边缘和外围。由于绿洲发展改变了水资源的时空分配和消耗方式，使得人工绿洲与沙漠同时扩大，而处于两者之间的自然水域、林地、草地面积和野生动物数量减少，形成沙漠危逼绿洲的态势。所带来的有利影响是水资源利用效益提高，土地生产潜力得到发挥，人工绿洲小气候条件改善，人口承载能力增加；不利方面是水土、水盐平衡失调，生物多样性减少，沙漠与绿洲间过渡带缩小。为了适应西北地区人口和经济增长，预测未来绿洲发展，将以提高现有绿洲生产潜力为主，重点是加强中低产田改造；通过节水及水资源合理调配，适度扩大新绿洲。以保护自然生态来维护人工绿洲生态的稳定性，以发展人工绿洲生态来减轻自然生态的压力，实现可持续发展。     

Spatiotemporal dynamics of land cover and their impacts on potential dust source regions in the Tarim Basin,NW China

Human-driven dynamics of land cover types in the Tarim Basin are able to affect potential dust source regions and provide particles for dust storms. Analyses about dynamics of potential dust source regions are useful for understanding the effects of human activities on the fragile ecosystem in the extremely arid zone and also provide scientific evidence for the rational land development in the future. This paper therefore selected the Tarim Basin, NW China, as a representative study area to reveal spatiotemporal dynamics of land cover and their impacts on potential dust source regions. The results showed that farmland, desert and forest increased by 28.63, 0.64 and 29.27%, while grassland decreased by 10.29% during 1990–2010. The largest reclamation, grassland loss and desertification were 639.17 × 10³, 2350.42 × 10³ and 1605.86 × 10³ ha during 1995–2000. The relationship between reclamation and grassland loss was a positive correlation, while a highly positive correlation was 0.993 between the desertification and grassland loss at different stages. The most serious dust source region was the desertification during 1990–2010 (1614.58 thousand ha), and the serious region was stable desert (40,631.21 thousand ha). The area of the medium and low dust source region was 499.08 × 10³ and 2667.27 × 10³ ha. Dramatic reclamation resulted in the desertification by destroying natural vegetation and breaking the balance of water allocation in various regions.     

城市地表温度对土地利用/覆被变化响应的遥感研究——以乌鲁木齐为例

 快速的城市化对城市环境产生显著的影响,基于遥感定量研究地表温度对土地利用/覆被变化（LUCC）的响应,来评估快速城市化对环境的影响,是一种快速、有效的途径。以干旱区典型绿洲型城市——乌鲁木齐为例,将遥感与地理信息系统相结合,利用1990年和2009年两期陆地卫星影像为基础数据进行土地利用/覆被分类,并基于单窗算法定量反演同期的地表温度,从而对快速城市化进程中的土地利用/覆被类型动态变化的空间特征及地表温度对快速城市化的响应情况进行了定量研究。结果显示,在近20 a间,乌鲁木齐城市迅速扩张,土地利用/覆被类型变化显著,城市建设用地增长率高达44.73%;同时城市的快速发展使地表温度提高了近6 ℃。研究表明,温度变化格局,尤其是增温区的空间分布与城市扩张的空间格局基本一致,说明地表温度对城市的土地利用/覆被变化产生了显著的响应。     

近40年台特玛-康拉克湖泊群水域变化遥感监测

车尔臣河下游自1989年改道以来,河道北边形成若干小湖,使台特玛湖-康拉克地区的水域格局发生了很大变化.干涸30多年的台特玛湖,随着自2000年起塔里木河下游应急生态输水工程的实施开始形成大片水域,且水域面积呈扩大趋势.2002年车尔臣河改道结束后康拉克地区的湖泊格局基本形成,而台特玛湖地区的水域则继续大幅变化.本文在1972-2012年102期遥感影像及其相关辅助数据基础上进行各项定量分析,详细描述台特玛湖-康拉克地区的水域变化过程,总结变化趋势,试图找出变化主导因素.笔者认为台特玛湖-康拉克地区的湖泊水域景观格局变化自1970s-2000年主要受车尔臣河径流量年际变化的控制,而21世纪以来则主要受塔里木河下游应急生态输水工程措施的影响.