【作者】 张晓龙；

【导师】 李培英； 刘月良；

【作者基本信息】 中国海洋大学 ， 环境工程， 2005， 博士

【摘要】 湿地是地球上自然生产力最高的生态系统之一,滨海湿地是其重要类型。现代黄河三角洲滨海湿地由于具有显著的原生性、脆弱性、稀有性,作为鸟类栖息地、繁殖地和中转站,在国际上具有重要地位,近年来吸引了不少国内外学者对其进行研究,取得了颇多成果,但有关其环境演变及退化方面的研究还较少。本文通过实地调查,运用多种手段,对现代黄河三角洲滨海湿地的环境演变及退化过程进行研究,并对其退化进行评价,得到如下主要结论: (1)现代黄河三角洲滨海湿地的演化发育是在黄河泥沙淤积形成的沉积体叶瓣上发生的,与黄河来水来沙量有着密切的关系。1976年以来,黄河改走清水沟流路期间,新叶瓣的发育经历了扇形平面展开、纵向突出伸展、横向扩展、废弃改造4个阶段;1996年清8改汊后,由于黄河水沙来源的减少和年际差异,新沙嘴呈现出频繁的蚀淤交替变化。加之人类活动的影响,滨海湿地的发育演化具有了新的特点,包括人类和自然等各种外界干扰的存在,是其不断演化发育的外部条件。 (2)新生湿地上的植被随新生陆地的进退变化而发生顺向或是逆向的发育演替,但总体上具有明显的盐生特征。芦苇是新生滨海湿地上的优势群落。初步调查显示,随着滨海湿地的淤高、河口的伸展,在以草本群落为主的生态系统中,沿河口向上游生物量逐渐下降。 (3)现代黄河三角洲滨海湿地物质组成以粉砂为主,环境化学特征具有显著的区域差异,现行水河口区、废弃河口区及油田分布区有明显不同;不同的生境条件下亦有明显差异。分析化学要素之间的关系发现,选取的22种化学成分在现代黄河三角洲滨海湿地具有很好的共生组合性;有机质含量与含盐量有正相关关系,反映了当地的盐生环境。 (4)在遥感影像分类基础上,运用景观生态学方法研究表明,20年来,海域始终是现代黄河三角洲滨海湿地最大的一种景观类型,而且面积在不断扩大,各种湿地景观类型转为海域的面积总和达2.72万ha,而海域转为其它类型的面积仅为0.45万ha,说明滨海湿地损失严重;所有景观类型中变化最大的是水域,突出反映了养殖开发造成的滩涂景观变化。景观格局指数的变化表明,20年来现代黄河三角洲滨海湿地景观破碎化加深,其中人类活动起了主要作用;植被指数显示,植被覆盖面积减少,质量变差,盖度降低,植被覆盖整体趋向恶劣。滨海湿地退化趋势明显。 (5)现代黄河三角洲滨海湿地的损失退化是一个复杂过程,其发生原因是多方面的,包括海岸侵蚀、海面上升、风暴潮灾、黄河断流、油田开发、滩涂围垦、更多还原

【Abstract】 Coastal wetland is an important type of wetland, one of the highest productivity of ecosystem on the earth. Due to its remarkable primordial, vulnerability and scarcity, the Modern Yellow River Delta coastal wetlands (MYRDCW), as a place for birds to inhabit, reproduce and migrate, plays a very important role internationally. In recent years, it has attracted many domestic and international researchers to study it. The achievements have been fruitful. But there are few studies on its environmental evolvement and degradation. Supported by findings from field surveys and other means, the research in this paper studies the environmental change and degradation, and evaluates its degradation as well for MYRDCW.MYRDCW has evolved and developed on the lobe of deposit body. It has close relationship with water and sand in Yellow River (YR). From 1976 to 1996, during the period when YR flowed along Qingshuigou, the development of new lobe has undergone four phases: outspread on the plane shaped like a sector, expansion on lengthwise orientation, enlargement on widthwise orientation and alteration after abandoned. Because of the decrease of the amount of sand sources in YR since it changed its course at Qing 8 in 1996, the new spit of the river mouth started to have the characteristic of frequent alternated between erode and silt. Impacted by human activities, the development of coastal wetland has shown new characteristics. The disturbance from sources including mankind and the nature are external conditions for it to develop and evolve continuously.With the extension or erosion of new land, the vegetation develops and carries out straightforward or converse succession on the newborn wetlands. But overall it has the characteristic of apparent saline characteristics. Reed is the predominant community on the newborn coastal wetlands. As the coastal wetland is silted higher and the outfall extending, the biomass in the ecosystem mainly consisting of herbaceous plant community gradually decreases going upstream along the river.Experimental data indicates that silt is the predominant component in MYRDCW. The environmental chemical characteristics differentiate each other remarkably among different regions such as the current outfall area, abandoned outfall area and oil field area. Under the different habitats of reed, iodine weed, chionese tamarisk and beach land, all factors what have tested also show apparent differences. The analysis of the relationship among the chemical elements indicates the chosen 22 elements have the characteristic of very good co-existing combination in MYRDCW. The amount of organics and the salinity have a positive correlation. This reflects the area’s saline environment. The amount of organics and granularity has a negative correlation, which indicates the composition of particles size affects the enrichment of organics.Based on interpretation of remote sensing (RS) images and its classification, methodology of landscape ecosystem was adopted to study the changes of landscapepattern from 1984 to 2004 in MYRDCW. In the past 20 years, sea area has always been the greatest class type, and it has been always expanding. The total area transformed from other wetland type to sea area has reached 2.72x10 ha, while the total area transformed to sea area from other types is only 0.45xl04ha. This is how serious the wetland loss is. Among all types, water area has changed the most, which reflects the massive changes resulted from development of tidal-flat aquiculture.The calculation of landscape pattern index indicates in the past 20 years the overall number of landscape patches has increased in MYRDCW. The landscape diversity has had some improvements but it is not remarkable. The level of fragmentation is not high. But the change trend of the regions is the number of patches increases; the index of mean area, mean nearest-neighbor distance and mean proximity decreases; landscape fragmentation gets more serious. Human activities contribute the most to the changes. The statistics of vegetation index indicate in MYRDCW, the area of vegetation coverage has decreased; wetland quality has worsened; coverage degree has decreased; and the overall vegetation coverage has become worse. This indicates that the degradation of the coastal wetland is obvious.Causes of degradation of MYRDCW include natural processes and human activities such as coastal erosion, sea level rise, storm surge, the break-flow of YR, development of oil field, tidal-flat reclaim, overfishing, construction of road and seawall, pollution, etc. The loss and degradation of MYRDCW is a complicated process. The influential factors are not working in an isolated fashion. The natural processes and human actions can not be separated completely. They work together to cause the constant changes of coastal wetland.The natural processes have created the base for MYRDCW. But human activities increase; development activities speed up; natural appearance changes remarkably; the quality of environment keeps declining; ecological structure is being destroyed; ecological function seriously declines; productivity decreases. Coastal wetland degradation started to happen and it’s becoming worse and worse.This paper evaluates the degradation of MYRDCW by creating evaluation model with help of fuzzy mathematics methods. The evaluation results indicate that the degradation in the oil field area is the worst. It can be categorized as severe degradation. The degradation can be categorized as minor degradation in the newborn wetland nature reserve including the outfall area of YR and Yiqianer reserve. But due to the fact that they play an important role in MYRDCW, we can’t really feel relieved with their level of degradation. As a whole, MYRDCW is in a state of minor degradation. But the degeneration is speeding up and is seriously threatening the health and safety of coastal wetland.Through field surveys, interpretation of RS images, analysis of data, it can be concluded that the degradation of MYRDCW will not stop in the near future and be a trend. It’ll continue affecting the structure, function and value of the coastal wetland ecosystem.更多还原