高寒草甸及湿地是青藏高原上最为重要的生态系统,它的状况直接关系到我国江河源头的蓄水量,也关系到我国中部和东部广大地区的工农业及人民生活用水,因此对青藏高原高寒草甸与湿地的保护具有重要的现实意义.本研究对青藏高原东北缘黄河源头地区甘南藏族自治州的玛曲县高寒草甸及湿地进行调查,揭示了该地区的植被生物多样性情况与组成结构,利用解析层次方法分析了高寒草甸及湿地的退化原因及恢复手段,同时还从集合种群竞争原理出发对该地区植被生物多样性的维持机理进行了讨论.结果显示出两个现存的主要矛盾:在生物多样性保护与高寒草甸质量提高方面存在矛盾;在地区发展与高寒草甸质量提高方面也存在矛盾.前者表明为了提高物种多样性,必须存在一定干扰,包括人为干扰与自然生态系统干扰,这些干扰会在高寒草甸中形成一定数量的空斑块,这些空斑块为先锋种的繁殖提供了暂时的场所从而使多样性得到提高与维持.但由于先锋种普遍为杂草类而非优良牧草,因此这种多样性维持只能以牺牲草甸质量为代价.第二个矛盾说明为了提高当地经济与社会发展,必然会增加人为干扰,而这些干扰会首先对优良牧草造成不利,从而使杂草比例增加并进一步抑制牧场质量从而限制地区以畜牧业为主的经济发展.%Alpine meadow and wetland,closely correlated with the amount of water stock in the riverhead of China,is the most important ecosystem of the Qinghai-Tibetan Plateau.This ecosystem is the primary support for the industrial and agricultural and the living using water in the middle east of China,which makes the conservation of alpine meadow and wetland in the Qinghai-Tibetan Plateau have importantly practical significance.This paper presents the composition structure of plant biodiversity in Maqu,a county of Gannan Tibetan Autonomy Prefecture and located at the northeastern edge of the Qinghai-Tibetan Plateau,which is the riverhead of the Yellow River.With the analytic hierarchy process,the reasons of deterioration and the measurers of restoration are given.By the competition theory of metapopulation,we have also presented the underlying mechanism of the maintenance of biodiversity in this region.Results show there are two contradictions between biodiversity conservation and improvement of meadow quality,and between local economic and social development and meadow quality maintenance.The first contraction suggests that high species richness needs moderate artificial and natural disturbance,which can create some patches in the habitat.These patches will be the temporal reproducing locations for pioneer species that primarily consist of low-quality ruderal,and will cost some patches for high-quality fodder.Secondly,the increasing of artificial disturbance,as a directly result of economic and social development,will be disadvantage to the maintenance of high-quality meadow and might exclude some dominated species,which will restrict the development of local animal husbandry.
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