【作者】 田应兵；

【导师】 宋光煜；

【作者基本信息】 西南农业大学 ， 农业资源利用， 2003， 博士

【摘要】 湿地因其巨大的生产功能和生态环境效益而被誉为“人类摇篮”、“生物基因库”和“自然之肾”，湿地生态系统也因此与森林、海洋一起并称为全球三大生态系统。二十世纪以来，随着人口的剧烈增长和社会经济的飞速发展，自然湿地愈来愈多地受到人类的干扰，但其总体效果是破坏大于保护，导致湿地面积减少、生物多样性降低、污染严重、功能退化甚至丧失，并已引起全世界的广泛关注。针对湿地的退化情况，近一、二十年来世界各国都在采取积极的措施进行湿地生态恢复的研究与实践，湿地生态系统的恢复与重建课题已成为世界性的研究热点。但是研究区域多集中在平原河湖湿地和北方泥炭地，对于我国独有的青藏高原(也是对全球气候变化最为敏感的区域之一)湿地则少有涉及。 若尔盖湿地位于青藏高原东部，是我国独有的青藏高原湿地的一部分，它包含了约100万hm~2的泥炭沼泽、苔草沼泽、湖泊和湿草地。如此大面积的高海拔沼泽地在世界范围内相对罕见，从而确立了若尔盖湿地的生物多样性具有全球意义以及其在区域气候变化中的重要作用，但近半个世纪的开发利用导致了若尔盖湿地的生态特征发生改变，湿地的功能削弱，土壤退化、砂化甚至荒漠化。自1990年实施湿地生态恢复措施以来，湿地退化减缓，区域湿地生态环境有所改善。另一方面，该区域为我国五大优良牧场之一，人、畜的缺硒症状时有发生，人民健康和畜牧业发展均受到较大的影响和危害。 为此，中国国家林业局于1999年正式启动了一项由中华人民共和国政府（CPR）、联合国开发计划署（U’NDP）It球环境基金（GEF）联合组织的国际合作项目一中国湿地生物多样性保护与可持续利用（项目编号汇PR／98／G32lAll G／99人该项目旨在解决具有全球生物多样性保护意义的四个有代表性的不同项目地点（三江平原、若尔盖湿地、盐城和洞庭湖）的湿地保护和湿地生态功能的恢复等问题。本研究属于该项目的一部分，并以若尔盖湿地为对象，重点研究了若尔盖高原湿地生态恢复过程中若干生态特征及湿地土壤碳、硒的变化，以期获得相关的基础研究资料。本研究采用野外调查的方法，通过对沼泽湿地水分、植被和土壤变化以及区域经济发展的分析，阐述了湿地生态特征变化对湿地生态系统的恢复、水分涵养和防止于旱的重要作用；采用田间腐解试验，通过对土壤有机质的数量、组成和质量的变化以及碳在植物一土壤系统中的流动的研究，探讨了高原湿地生态环境对土壤有机碳的积累和分布的影响、湿地植物对大气碳的固定和碳在区域湿地生态系统中的作用，试图为高原湿地的生态恢复与资源利用提供理论依据；采用盆栽试验方法，通过对高原湿地土壤硒的数量特征、形态和分布、湿地生态环境与硒的有效性的关系、硒对黑麦草u…LamaUbade）的生长和谷肮甘肽过氧化物酶（GSHds）活性及根系活力的影响的研究，探讨了湿地低硒环境下硒的有效利用途径和硒对黑麦草的必需性，试图为该区域人畜缺硒症的防治提供科学指导。研究的主要成果如下： l、在过去的十多年里，随着湿地保护意识的加强，若尔盖高原湿地区域采取了一系列生态恢复措施。通过退牧还草还水恢复原有湿地面积，采取轮牧禁牧措施保护现有湿地：实施沙漠化治理工程和建立湿地自然保护区抑制湿地的退化；通过填埋沟渠去提高地下水位抑制沼泽旱化。由此引起湿地生态特征发生变化，总体效果是高原湿地的生态环境得到改善，湿地生态系统的结构与功能得到稳定与强化。上述诸多措施中，水体恢复与水质改善是该区域湿地生态系统株复的关键性因素． 2、若尔盖高原湿地生态系统的特征变化表现在四个方面。一是水面扩大和湿地地表水水质状况良好。调查结果表明，实施生态恢复措施的十年间，共填埋沟渠200kin以上，恢复沼泽面积达 5万 bm，恢复湖泊水面达 1000inn＼沼泽地贮水量增加了 1．5X旷m3，增长了 7．5％。水面扩大和蓄水量的增加为防止黄河断流及草原干旱提供了重要的水源保障。以1类水质标准评价，仅有溶解性铁、油、CODcr、NHs和pH值超标。其中油和有机物污染主要由人为因素引起，其他项目超标为沼泽固有的自然因素所致。良好的水环境既为人畜提供了清洁用水，同时也为区域湿地生态系统的稳定奠定了基础。二是随着地表水分状况由湿润到地表积水的变化，湿地植物群落由中生或 2湿中生向湿生或沼生群落演替，群落结构趋于简单，表现出由藏嵩草（Kobreiadbe伽＼线叶嵩草（ Cp帅峋、无脉苔草po ennrvis）、花苹驴蹄草（Calthas一 j等多优势种分布向以木里苔草（C muhe。is）和乌拉苔草（C m叭则为主的单优势种分布的变化趋势，但植物群落的生物量逐步增加，生态系统的初级生产力提高。三是湿地土壤由风沙土一草甸土一沼泽土一泥炭土恢复演替，在这一演替序列中，土壤的有效水分含量大幅度增加，土壤全N、全P、有效N、P、K含量亦明显增加，表现出与湿地生态环境变化的一致性，全K含量则受母质和水热条件影响较大。四是湿地资源在开?更多还原

【Abstract】 Wetland is called "the cradle of mankind’\ "a gene pool of living things" and "the kidney of nature " because of huge productiveness, ecological and environmental values. Wetland, forest and ocean are the three most important ecosystem on earth. With the violent increase of world population and rapid development of economy, wetland degrades for the changes of ecological character in wetlands ecosystem including decrease in wetland area, water pollution, biodiversity reduction and weakened function of wetland for mankind disturbing since 20th century. Some effective measures are adopted to prevent the degradation of wetland in many countries around world and the study on restoration and rebuild of degraded wetland ecosystem has been a focus in the past 20 years. Many works have been done in studying wetland ecosystem in plain and northern peat land, but little is reported on the same work at Qinghai-Tibetan Plateau in China, which is one of the most sensitive areas on global climate chnge in the world.Ruoergai wetland lying in the north-eastern part of Qinghai-Tibetan Plateau in China, covers an area of 1 million hm2 including moor, carex swamp, lakes and wet prairie. The global meaning of biodiversity and the important role on global climate change are ensured at the region because of vast area of high altitude moor land rare in the world. However, the excessive human activities resulted in the changes of wetland ecological character, the weakness ofwetland function, wetland soil degradation or desertification during half a century. Since 1990’s, some measures of ecological restoration have been taken and the ecological environment has been improved. On the other hand, the people’s health and the development of livestock husbandry are damaged due to the selenium response symptom (SRS) in the region, which is one of the five big pastoral areas in China.As was stated above, State Forestry Administration(SFA) began to carryout an international cooperated project------The biodiversity protection ofwetland and its sustainable utilization in China (Project No.:CPR/98/G32/A/lG/99), which was from three units including People’s Republic of China (CPR),United Nations Development Program (UNDP) and Global Environment Fund (GEF) in 1999. The purposes of the project were to resolve question on protection and foundation restoration of wetland at four places (Sanjiang Plain,Ruoergai Plateau,Yian Cheng and Dongting Lake) where there were significance of the global biodiversity protection in China. This study was a part of the project and several ecological characters and changes of soil C and Se in the process of wetland ecological restoration were researched to require related information for the project in Ruoergai Plateau. Based on analysis of the changes of wetland water, vegetation, soils and economic development by field investigating, the study pointed out the important effects of ecological character change on the restoration, conservation of water and anti-drought in wetland ecosystem, also the influences of wetland ecological environment on accumulation and distribution of soil organic C, C fixation of wetland plant from atmosphere, and effect of C in wetland ecosystem using a field decomposition approach based on changes of quantity, formation and quality of soil organic matter, and C flow from plant to soil to provide theoretical foundation for the ecological restoration and resources utilization of wetland in Ruoergai Plateau. By studying the quantities and species, distribution of soil Se, the relationships between wetland ecological circumstances and Se efficiency, the effects of Se on growth, Glutathione Peroxidase (GSH-Px) activity and root activity of ryegrass (L. muliflorum Lamaubadd), it also explored the effective utilizing way of wetland soil Se under Se deficiency and the essentiality of Se on rye grass using a method of pot experiment to give a scientific guide of preventing and curing the SRS. The main research results were as follows:1. A series of ecological measures had更多还原