【作者】 于堃；

【导师】 王颖；

【作者基本信息】 南京大学 ， 自然地理学， 2011， 博士

【摘要】 湿地作为人类共同的财富,与森林、海洋并称为全球三大生态系统,具有调节全球气候、控制土壤侵蚀、保持生物多样性、涵养水源、蓄洪防旱、降解污染物,防止自然灾害等独特的生态功能。因此湿地又被称为“天然水库”、“地球之肾”、“生物基因库”。由于其处于地球表面各个圈层相互作用的敏感区域,对湿地研究既有助于人类更深入的认识全球气候变化,也有助于人类可持续的开发利用湿地资源。文章依据我国湿地分类系统选取我国的三种典型的湿地类型,包括湖泊湿地(洪泽湖湿地)、滨海湿地(盐城湿地)、河口湿地(崇明东滩湿地),以及美国的沼泽湿地(Everglades;显地)作为研究对象,通过对历史资料的分析并结合实地考察对比分析了四种湿地的成因、发展、现状以及四种湿地所处的不同地理环境、人类活动强度。利用近10年来各个研究区的共计1821景MODIS (Moderate Resolution Imaging Spectroradiometer) 250 m分辨率的遥感影像对各个研究区的植被进行长时间序列的连续监测,分析评价了Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI)和Floating Algae Index (FAI)对不同区域的适应性。选取最优指数计算各个区域的累计植被面积指数AVCAs (accumulated vegetative coverage area)以及高植被覆盖天数SVCDs (significant vegetative coverage days),结合区域气象观测资料以及区域耕地面积统计资料,分析、评价了近10年来四种湿地类型的植被在人与自然相互作用下的演化动因和趋势,针对不同湿地类型的特殊地理环境,提出不同湿地类型的植被开发及保护建议,并得出如下结论：(1)洪泽湖国家自然湿地保护区是江淮地区典型的湖泊湿地,受河流、湖泊及古海洋的共同作用。历史上地壳断裂形成的凹陷、第四纪海侵以及淮河入海不畅是洪泽湖湿地形成的自然因素,而大规模的屯垦以及治水工程则是洪泽湖湿地形成的人为因素。江苏盐城国家级珍禽自然保护区是我国最大的滨海湿地保护区,受河流及海洋的共同作用。历史上海岸线变迁是影响盐城湿地形成及演化的主要自然因素,而人为改道黄河以及引种米草则是促使盐城湿地演化的人为因素。崇明东滩国家级自然湿地保护区是一处典型的快速演替的河口潮滩湿地,受河流及海洋的共同作用。历史上河海交互作用下的长江泥沙沉积是影响崇明东滩湿地形成及演化的主要自然因素。Everglades沼泽湿地保护区东临大西洋,西面墨西哥湾,背靠佛罗里达州最大的Okeechobee;淡水湖,受河流、湖泊及海洋的共同作用。历史上地壳运动引起的佛罗里达地台不断抬升所形成的北高南低的特殊地貌是Everglades召泽湿地形成及演化的主要自然因素,而人工渠道的修建以及疏干计划的实施是影响该湿地演化的人为因素。(2)2000-2009年间洪泽湖湿地保护区全域以及其核心区的AVCAs和SVCDs总体趋于下降。其中2000-2008年间下降速度最快,表现为保护区全域的AVCAs由2000年的13.63×104km2 d降低至2008年的13.17×104km2d, SVCDs由2000年的360 d降低至2008年的282 d。核心区的AVCAs由2000年的3.62×104km2d降低至2008年的3.18×104km2d, SVCDs由2000年的78 d降低至2008年的23 d。对于洪泽湖湿地保护区全域而言,相关性分析表明,年降水与AVCAs和SVCDs呈显著负相关,年日照时数与AVCAs和SVCDs呈显著正相关,年耕地面积与AVCAs和SVCDs呈显著负相关。对洪泽湖湿地保护区的核心区而言,年日照时数与AVCAs和SVCDs呈显著正相关,而年耕地面积与AVCAs和SVCDs无显著相关性。同时,对比核心区与其周边农田的FAI值发现,近10年间洪泽湖湿地保护区核心区内无大规模的农业种植活动。另,洪泽湖是淮河流域最大的湖泊,而洪泽湖湿地核心区紧邻洪泽湖畔,因此洪泽湖湿地的AVCAs和SVCDs容易受到洪水的影响,这也在2003年的洪水事件中得以证实,并且洪水对该湿地AVCAs和SVCDs的影响在其后的若干年里一直持续。这说明湖泊湿地植被演化除气象因素以及人类农业活动的影响外,也受其特殊的地理环境影响。(3)2000-2009年间盐城湿地保护区全域以及其核心区的AVCAs和SVCDs总体趋于下降。表现为AVCAs由2000年的200.15×104 km2 d降低至2009年的188.84×104 km2 d,SVCDs由2000年的142 d降低至2009年的81 d。核心区的AVCAs由2000年的12.54×104km2 d降低至2009年的11.72×104 km2d, SVCDs由2000年的27 d降低至2009年的5 d。对于盐城湿地保护区全域而言,相关性分析表明,年降水与SVCDs呈显著正相关,年耕地面积与SVCDs呈显著负相关。对盐城湿地保护区的核心区而言,年积温与AVCAs和SVCDs呈显著正相关,而年耕地面积与AVCAs和SVCDs无显著相关性。同时,对比核心区与其周边农田的FAI值,发现近10年间盐城湿地保护区核心区内无大规模的农业种植活动。另,盐城湿地濒临黄海,其岸线目前总体上处于侵蚀状态。岸线的蚀退导致的土地面积减少将直接影响到沿岸滨海湿地的AVCAs和SVCDs值的变化。因此,除气象因素以及人类农业活动外,岸线变迁也是影响滨海湿地植被演化的另一个重要因素。(4)2000—2009年间崇明东滩湿地保护区全域的AVCAs和SVCDs总体趋于下降。表现为AVCAs由2000年的11.20×104km2 d降低至2009年的10.90×104km2d, SVCDs由2000年的124 d降低至2009年的109 d。而崇明东滩湿地保护区核心区的AVCAs由2002年的2.34×104km2 d上升至2009年的2.39×104km2d, SVCDs由2002年的216d上升至2009年的280 d。对于崇明东滩湿地保护区全域而言,相关性分析表明,年降水与AVCAs和SVCDs呈显著正相关,年耕地面积与AVCAs和SVCDs无显著相关性。对崇明东滩湿地保护区的核心区而言,气象要素及年耕地面积均与AVCAs和SVCDs无显著相关性。同时,对比核心区与其周边农田的FAI值,发现近10年间崇明东滩湿地保护区核心区内无大规模的农业种植活动。另,崇明东滩湿地位于长江入海口,受河海交互作用影响,由于长江泥沙的不断淤积,崇明岛仍然继续着每年平均约150-230 m的速度向东海延伸的势头。湿地面积的淤涨使得该湿地全域的AVCAs和SVCDs的降幅要明显缓于其他几个湿地,同时该湿地的核心区的AVCAs和SVCDs是所选湿地类型中唯一趋于增长的湿地类型。所以除气象因素外,河海交互作用导致的湿地面积淤涨是影响河口湿地植被演化的另一个重要因素。(5)近10年间Everglades湿地保护区的SVCDs始终稳定在365 d—366 d,而AVCAs则由2000年的155.06×104 km2 d降低至2009年的153.77×104km2 d。相关性分析表明,年积温和年降水均与其AVCAs呈显著正相关。同时,对比Everglades湿地保护区与其周边农田的FAI值,发现近10年间湿地Everglades保护区内无大规模的农业种植活动。另,Everglades沼泽湿地沿岸多为红树林,起到了一定的护岸作用,所以近年来Everglades沼泽湿地的面积基本没有发生变化。因此气象因素是影响该湿地的植被演化的一个重要因素。(6)四种不同类型湿地近10年的AVCAs和SVCDs曲线趋势线斜率表明,对于四种湿地全域而言,盐城湿地全域的AVCAs和SVCDs曲线下降速度最快,而崇明东滩湿地全域的AVCAs和SVCDs曲线下降速度最缓。对于核心区而言,洪泽湖湿地核心区的AVCAs和SVCDs曲线下降速度最快,崇明东滩湿地核心区AVCAs和SVCDs曲线则表现为上升趋势。同时FAI指数表明,我国的三种类型湿地的核心区内均无大规模的农业种植活动,而核心区以外区域均有不同程度的农业种植活动。(7)对三种植被指数(NDVI、EVI、FAI)的评价结果表明,EVI指数在农田以及包含农田的植被盖度相对较高的区域表现最为优越,因此EVI更适合用于评价洪泽湖湿地全域、盐城湿地全域以及崇明东滩湿地全域的植被。而对于以天然植被为主以及植被盖度相对较低的区域,FAI表现最为优越,因此FAI更适合用于评价洪泽湖湿地核心区、盐城湿地核心区、崇明东滩湿地核心区以及Everglades湿地全域。(8)针对不同湿地的演化动因并结合开发现状,提出如下湿地植被保护及可持续利用策略。洪泽湖湿地的可持续利用策略包括：退耕还湿,稳定湿地面积；优化调整农业结构；严格限制洪泽湖核心区开发；适度开发洪泽湖湿地的旅游资源；改善入湖水质。盐城湿地的可持续利用策略包括：优化农业结构；科学维护植物物种多样性；严格控制污染源；适度开发湿地生态旅游。崇明东滩湿地的可持续利用策略包括：动态划分湿地生态安全界线；增强植被多样性；合理利用及保护湿地水资源。Everglades;湿地的可持续利用策略包括：调控水资源；恢复地表水流自然流通；改善水质。更多还原

【Abstract】 Wetlands, together with the forests and oceans, are regarded as the treasures of human and the most important ecosystems on the earth. They have some special ecological functions, such as adjust the globe climate, control the soil erosion, protect the biodiversity, conserve the water resource, prevent the floods and drought, degrade the pollutions and prevent other the potential natural disasters. Thus, wetlands are called "the natural reservoir", "the kidney of the Earth" and "the gene pool". Wetlands are very sensitive because they associate with Atmosphere, Lithosphere, Biosphere and Hydrosphere, so wetlands research will improve our understanding of the globe climate change and the sustainable utilization of wetlands. In this work, four different types of wetlands are chosen, including Hongze wetland (lake wetland), Yancheng wetland (costal wetland), Chongming Dongtan wetland (river mouth wetland) and Everglades wetland (marsh wetland), according to the wetlands classification systems of China (Tang & Huang,2003). History records, field work data, local meteorological data, agricultural activities records and 10 years Moderate Resolution Imaging Spectroradiometer (MODIS) 250-m resolution images are used to study the formation, the development, the driving factors and the trend of the vegetation coverage change of these four wetlands under the interactions caused by both anthropogenic (e.g., agricultural activities) and natural (e.g., climate change) effects. Three vegetation indices (VIs) including Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Floating Algae Index (FAI) are compared to evaluate their effectiveness in assessing relative changes of these four wetlands. AVCAs (accumulated vegetative coverage area) and SVCDs (significant vegetative coverage days) are calculate by the selected VIs. By evaluating the difference of the geographical environments, some suggestions and conclusions for the sustainable utilization of these four wetlands’ vegetation are finally given out:(1) Hongze wetland is the typical lake wetland in the watershed of Huaihe and Yangtze River impacted by rivers, lake and quaternary marine transgression. The history records show that the process of the formation and the development of Hongze wetland are affected by both natural and anthropogenic effects. Depression caused by crustal fault, the quaternary marine transgression and deposition of sediment in Huaihe River channel are the main natural effects, and the large scale agricultural activities and water control program are the main anthropogenic effects. Yancheng wetland is the largest coastal wetland impacted by both river and ocean. The history records show that the process of the formation and the development of Yancheng wetland are affected by both natural and anthropogenic effects. The shoreline change is the main natural effect, and the channel change of Yellow River and the spread of Spartina are the main anthropogenic effects. Chongming Dongtan wetland is a typical river mouth wetland impacted by both river and ocean. The history records show that sediment deposition of Yangtze River by river-sea interactive is the main natural effect and affects the process of the formation and the development of Chongming Dongtan wetland. Everglades wetland located among Okeechobee Lake, the Atlantic Ocean and the Gulf of Mexico, so it was affected by rivers, lake and oceans. The history records show that the process of the formation and the development of Everglades wetland are affected by both natural and anthropogenic effects. The rising of Florida platform caused by crustal movements is the main natural effect, and the implementation of Everglades Drainage District (EDD) plan and the construction of the channels are the main anthropogenic effects.(2) The AVCAs and SVCDs of Hongze wetland in both the whole and the core areas show degradation trends in the past 10 years. For the whole area of Hongze wetland, the AVCAs and SVCDs decreased quickly between 2000 and 2008. The AVCAs changed from 13.63×104 km2 d to 13.17×104 km2 d and the SVCDs changed from 360 d to 282 between 2000 and 2008. For the core area, the AVCAs changed from 3.62×104 km2 d to 3.18×104 km2 d and the SVCDs changed from 78 d to 23 between 2000 and 2008. For the whole area, correlation analysis shows that cropland acreage and annual precipitation collectively played significant negative roles in affecting the AVCAs and SVCDs. However, annual sunshine duration played a significant positive role. For the core area of Hongze wetland, correlation analysis shows that annual sunshine duration played a significant positive role in affecting the AVCAs and SVCDs. FAI shows that there are no large scale agricultural activities in the core area of Hongze wetland during the past 10 years. Hongze Lake is the largest Lake in the Huaihe watershed, and the wetland is nearby the Hongze Lake. Thus, flooding event caused a sharp drop of AVCAs and SVCDs in 2003, and the affect continued in the following years. Therefore, the degradation trends of the vegetation coverage of Hongze wetland are mainly caused by both the anthropogenic and the natural effects.(3) The AVCAs and SVCDs of Yancheng wetland in both the whole and the core areas show degradation trends in the past 10 years. For the whole area of Yancheng wetland, the AVCAs changed from 200.15×104 km2 d to 188.84×104 km2 d and the SVCDs changed from 142 d to 81 between 2000 and 2009. For the core area, the AVCAs changed from 12.54×104 km2 d to 11.72×104 km2 d and the SVCDs changed from 27 d to 5 between 2000 and 2009. For the whole area, correlation analysis shows that cropland acreage played significant negative roles in affecting the SVCDs. However, annual precipitation played a significant positive role. For the core area of Yancheng wetland, correlation analysis shows that accumulated air temperature played a significant positive role in affecting the AVCAs and SVCDs. FAI shows that there are no large scale agricultural activities in the core area of Yancheng wetland during the past 10 years. The coastal area of Yancheng wetland is generally in erosion condition and the erosion affected the change of AVCAs and SVCDs in this region. Thus, the degradation trends of the vegetation coverage in the core area of Yancheng wetland are mainly caused by both the anthropogenic and the natural effects.(4) The AVCAs and SVCDs of Chongming Dongtan wetland in the whole areas show degradation trends in the past 10 years. For the whole area of Chongming Dongtan wetland, the AVCAs changed from 11.20×104 km2 d to 10.90×104 km2 d and the SVCDs changed from 124 d to 109 between 2000 and 2009. For the core area, the AVCAs increased from 2.34×104 km2 d to 2.39×104 km2 d and the SVCDs increased from 216 d to 280 between 2002 and 2009. For the whole area, correlation analysis shows annual precipitation played a significant positive role in affecting the AVCAs and SVCDs. For the core area, correlation analysis shows that there are no significant roles among all of them. FAI shows that there are no large scale agricultural activities in the core area of Chongming Dongtan wetland during the past 10 years. Chongming Dongtan wetland is generally in accretion condition and the accretion rate is about 150-230 m yr-1. The accretion condition caused the AVCAs and SVCDs of the whole area decrease slowly and the AVCAs and SVCDs of the core area even increase. Thus, the change trends of the vegetation coverage in Chongming Dongtan wetland is mainly caused by the natural effects.(5) The SVCDs of Everglades keep stable between 365 d and 366 d during the past 10 years. However, the AVCAs changed from 155.06×104 km2 d to 153.77×104 km2 d between 2000 and 2009. Correlation analysis shows that annual accumulated air temperature and annual precipitation played significant positive roles in affecting the AVCAs. FAI shows that there are no large scale agricultural activities in the Everglades wetland during the past 10 years. There are many mangroves distributed alone the shoreline of the Everglades and they protect the shoreline from the erosion. Thus, the change of the AVCAs is mainly caused by the natural effects.(6) The slopes of the AVCAs and SVCDs plots show that, for the whole area, degradation trends of Yancheng wetland is listed the 1st and degradation trends of Chongming Dongtan wetland is listed the last. For the core area, degradation trends of Hongze wetland is listed the 1st, and the AVCAs and SVCDs plots of Chongming Dongtan wetland even shows increase trends. FAI shows there are no large scale agricultural activities in the core area of Hongze wetland, Yancheng wetland and Chongming Dongtan wetland. However, the agricultural activities still affect the area outside the core.(7) Three vegetation indices (VIs) are compared to evaluate their effectiveness in assessing relative changes. These are the Normalized Difference Vegetation Index (NDVI), the Floating Algae Index (FAI), and the Enhanced Vegetation Index (EVI). EVI is less sensitive than others in assessing croplands or the area including croplands. Thus, EVI is more suitable in assessing the vegetation of the whole area of Hongze wetland, Yancheng wetland and Chongming Dongtan wetland. FAI is less sensitive than NDVI and EVI to aerosol effects and shows less statistical error than NDVI and EVI in assessing lower vegetation coverage area, such as the area covered by natural vegetation. Therefore, FAI is chosen to study vegetation of the core area of Hongze wetland, Yancheng wetland, Chongming Dongtan wetland and the whole area of Everglades wetland.(8) Depending on the different process of the formation and the development of the four wetlands, following strategies are given out in order to protect and sustainable utilize the vegetation resource of the wetlands. For Hongze wetland: reconverting the farmland into the wetland; keeping the wetlands area stable; optimizing and adjusting the current agricultural structures; prohibiting agricultural activities in core area; moderate exploring the tourism; improving the water quality of Hongze lake. For Yancheng wetland:optimizing and adjusting the current agricultural structures; keeping species diversity;controlling the pollution; moderate exploring the eco-tourism. For Chongming Dongtan wetland:segmenting ecological security boundary dynamically; improving species diversity; utilizing and protecting water resource rationally. For Everglades wetland:controlling the water resource; recovering the natural outlet of the surface runoff; improving the water quality.更多还原