【作者】 童春富；

【导师】 陆健健；

【作者基本信息】 华东师范大学 ， 生态学， 2004， 博士

【摘要】 河口湿地生态系统是咸淡水交汇、陆海邻接的交错区，具有独特的结构与功能。同时，河口地区也是人口聚居、经济高速发展区域，人类对河口湿地的影响以及对相应生态系统服务功能的需求都日益增强。在河口湿地生态系统结构与功能研究基础上，将结构、功能与服务相联系，使河口湿地生态系统的研究更具有理论与现实意义。 本文以长江河口盐沼湿地生态系统为研究基地，选择河口湿地生态系统典型的生产者盐沼和数量较多、处于较高营养级的消费者鹆鹬类作为主要研究对象，将河口海岸动力过程、以及主要人为干扰因子作为整体环境背景，针对已有研究中的不足，通过环境与生物类群的整合分析，揭示长江河口湿地生态系统结构与功能特征。并首次在结构与功能研究基础上，通过生态系统服务价值评估及其与结构与功能变化特征的对应分析，揭示长江河口湿地生态系统服务功能特征及其与结构、功能的内在联系，为区域发展提供借鉴依据。 主要研究结果如下： 1．生产者组分结构与功能特征 (1) 高程变化是长江河口盐沼结构、生产力变化的主要驱动力。由于芦苇、互花米草高度、地上与地下生物量均显著大于海三棱藨草，芦苇、互花米草在与海三棱藨草之间的竞争中明显占优势，其竞争替代作用主要受高程制约，而不体现“资源比例假说”特点。环境条件对盐沼的胁迫强度随高程增加而减弱，相应成带分布的盐沼生产力与表形发生明显变化，整体生物量随着高程增加而增大。但华东师范大学博士学位论文摘要是，水体氮、磷营养盐过剩可能导致盐沼结构与功能的完全改变。特别是近50年来，长江径流输沙量呈显著下降趋势。如果输沙补充不能补偿盐沼沉积物由于营养盐过剩而造成的侵蚀，则可能造成滩面下陷，高程降低，进而使盐沼分布与种间关系特征发生明显改变。 (2)盐沼优势种在塑造栖息地环境条件过程中存在密切联系，海三棱蕉草具有潜在关键工程种特征(Keystone engineer)。海三棱蕉草由于具有减缓水动力、捕获泥沙功能，其生长特征与湿地高程具有互动变化特点，相应生长区具有快速淤高特性。海三棱蕉草通过改变高程，为芦苇、互花米草生长提供条件，促进竞争替代作用，即演替的发生;同时由于海三棱蕉草的作用，输入到较高盐沼生长区的泥沙减少，滩涂淤高速度趋缓，相应演替速率减慢，而使高滩植被，如芦苇在自然条件下能够维持较大的分布面积。(3)河口湿地盐沼优势种与非优势种的地下空间分异，导致竞争共存。与已有研究认为蕉草斑块能入侵海三棱蕉草生长区，并维持生长优势的原因是蕉草为地上、地下均占优势的双优竞争者不同，本文研究发现，在海三棱蕉草和蕉草交错区，海三棱蕉草表现为较好的地下竞争者，而蕉草为较好的地上竞争者。由于地下部分空间分布的差异，蕉草占据较上位地层，限制海三棱蕉草向上拓展;海三棱蕉草占据较下位地层，通过须根作用限制蕉草斑块拓展;而由于蕉草和海三棱蕉草地下主体部分分布具有明显的垂直分化，不至于发生竞争替代。海三棱蕉草与蕉草是在一定生态位分化背景下的竞争与共存。当然，也可能受环境条件的作用，还有待进一步研究。2消费者组分结构与功能特征 (l)鹃鹏在主要栖息地间分布并不均匀，而且存在季节差异。通常崇明东滩种类最为丰富，而三甲港、南汇边滩与九段沙鹃鹏种数对比关系具有季节性差异;鹃鹏的数量春季以崇明东滩最多，秋季则以九段沙最多，崇明东滩和九段沙鹤鹏分布数量通常占各栖息地鹤鹏整体的70%以上。不同栖息地物种组成的相似性，春季以崇明东滩和九段沙最高，秋季则以崇明东滩和南汇边滩较高;而三甲港边滩和其他区域的相似性通常相对较低。相对而言，栖息地整体条件的适栖性以崇明东滩最高，而三甲港边滩最低。华东师范大学博士学位论文摘要 (2)围垦是影响鹤鹏群落结构的重要因素。通常认为鹤鹏空间分布主要受底栖动物生物量分布的影响。但是根据底栖动物生物量与鹃鹏类空间分布特征分析发现，底栖动物生物量分布最高区域，鹤鹏种类、数量分布并不占优势，如三甲港边滩。底栖动物生物量对不同栖息地间鹃鹏分布的直接决定作用并不明显。而围垦对鹤鹏群落结构的影响较为突出。不同的围垦方式、围垦阶段对鹃鹏的影响具有一定差异。传统围垦模式工程施工过程中对鹤鹏影响较大，往往造成鹤鹏种类、数量的明显变化，而长期影响相对较小;新型围涂模式的工程施工对鹃鹏影响较小，但是由于其大范围改变鹤鹏栖息地条件，其长期影响较大，往往导致鹤鹏种类、数量的持续下降。 (3)潮间带湿地面积对鹤鹏整体分布具有较大影响。长江河口鹤鹏类已有研究认为，有效潮上坪为鹤鹏提供躲避潮水的场所，其分布面积对鹤鹏群落结构具有决定性作用。但是根据近年来的观测分析，长江河口鹤鄙类在高潮时通常迁飞往非潮汐区，包括己围垦的大堤内区域，因此有效潮上坪并不是决定因素。而潮间带是鹤鹏主要的觅食地，其面积大小对鹤鹏类的影响更为重要。崇明东滩在主要栖息地中潮间带面积最大，其鹤鹏种类、数量的变动通常对区域鹤鹏变动特征具有决定性作用。(4)区域不同鹤鹏?更多还原

【Abstract】 Estuarine wetland ecosystem is an ecotone where the fresh water meets the salt, and the land connects to the sea. It has unique structure and function to all the other ecosystems. But with the drastic population growth and fast urbanization development in the estuarine region, severe human disturbances were induced on the estuarine wetland, such as nutrient over-enrichment of estuarine water, wetland reclamation. On the other hand, it arose the tremendous requirements for ecosystem services, which may benefit the society. Linking the study from ecosystem structure and function to services of the estuarine wetland can be more important in such situation.This paper took Yangtze estuarine wetland ecosystem as a case study. Salt marsh and waders(Charadriiformes) were chosen as typical producer and consumer of the ecosystem. The estuarine and coastal dynamic processes and human disturbances were took as the context of the study. After studying the characteristics of ecosystem structure, function and services, "what is the linkage between structure, function and services of the estuarine wetland ecosystem" is the central question that the paper aimed to answer. Some questions about the structure and function that had not been solved validly before were also discussed. Major conclusions of the study are:1. Structure and function characteristic of the producer(1)Elevation variation determined the variation of the salt marsh structure and production. Along the elevation gradient from lower to higher, environmental stress on the salt marsh faded out gradually and salt marsh production went up. According to the height, above- and under-ground biomass allocation, Phragmites australis and Spartina alterniflora could be the win-win competitors to Scirpus mariqueter for above- and under-ground competition. The competitive displacement between the dominant species Phragmites australis ( or Spartina alterniflora} and Scirpus mariqueter did not show the characteristics of resource ratio hypothesis which put forward by Tilman(1982,1988), but lie on the upward growth of elevation. But the nutrients over-enrichment of the estuarine water may make things different. Especially in last 50 years, the sediment input to the estuary by river inflow had reduced dramatically. If the sediment input could not compensate the subsidence caused by nutrients over-enrichment, the elevation might decline, which might lead tothe change of salt marsh structure and function entirely.(2)Dominant salt marsh species had ties in habitat forming, and Scirpus mariqueter had some characteristics of "keystone engineer". Scirpus mariqueter could significantly slow down the water flow and trap the sediments, which led to the sediment accretion, elevation upward growth, and in turn the variation itself. Scirpus mariqueter modified the elevation, which provide the zonation chance for Phragmites australis and Spartina alterniflora and lead to the competitive displacement. At the same time, due to such function that Scirpus mariqueter carried out, sediment input to Phragmites australis and Spartina alterniflora zone and sediment accretion there declined significantly. Thus the Phragmites australis and Spartina alterniflora could maintain a tremendous distribution zone, and would not be displaced fast by other species, which distributed in the area on upper zone.(3) Different spatial distribution patterns of under-ground components led to the competitive coexistence of Scirpus mariqueter and Scirpus triqueter. Recently Sun et al. (2003) had concluded that Scirpus triqueter was the best above-ground and under-ground competitor to Scirpus mariqueter, which lead to the invasion success and clones maintaining of Scirpus triquete in Scirpus mariqueter zone. But current research had proved that Scirpus mariqueter could be the best under-ground competitor and Scirpus triqueter could be the best above-ground competitor at the edge of Scirpus triqueter tussoks which surrounded by Scirpus mariqueter. The Scirpus triqueter rhizomes distributed in upper stratum, which更多还原