【作者】 邓斌；

【导师】 龙瑞军； 尚占环；

【作者基本信息】 兰州大学 ， 草业科学， 2012， 硕士

【摘要】 在青藏高原黄河源区,选择高寒草地退化演替的四个阶段：禾草嵩草草地群落,矮嵩草草地群落,小嵩草草地群落与杂类草黑土滩群落和三种不同程度的围栏样地的恢复演替为研究对象。通过对各演替阶段群落植被物种、生物量、盖度、重要值和各种生态指数的测量,同时对土壤中有机碳、全氮、全磷含量及其生态化学计量比进行研究,得到以下结果：(1)在高寒草地退化演替的四个时期三个阶段中,群落植被的变化情况为：群落先是以禾草和嵩草为绝对优势种,生态优势度高,均匀度低,随着退化演替的进行,地上生物量、盖度逐渐下降,禾草嵩草重要值降低,杂类草开始入侵,杂类草重要值增加,群落物种数目增加,多样性指数得到提高,当演替变成杂类草黑土滩群落阶段时,群落变成以杂类草为绝对优势种,原生植被几乎消失,生物多样性和均匀度又回落,生态优势度升高。群落结构变得单一,生态、生产和生活功能丧失。(2)土壤养分流失,有机质、全氮含量随演替的进行而下降,随土层深度的加深而降低；全磷在演替初期下降,后来变化不显著；土壤有机质、全氮和C：N值与地上生物量表现出良好的相关性。(3)高寒草地的退化演替过程中,土壤养分具有较高的C：N比和较低的N：P比,且在不同的演替阶段具有不同的CNP生态化学计量比,表明高寒草地的退化演替过程中表现为N素的限制。确定青藏高原高寒草地退化其土壤养分的阈值为C：N>10且N：P>8。(4)高寒退化草地围栏封育能显著的提高草地群落的地上生物量、盖度,能很好的改善草地土壤养分状况,土壤有机质、全氮、全磷都得到了提高,对高寒草地的恢复具有重要作用。更多还原

【Abstract】 In the Yellow River source region of Qinghai-Tibet Plateau, we selected four alpine grassland stages of degradation succession: gramineae grass-Kobresia humilis community, Kobresia humilis community, Kobresia pygmaea community and the forbs-black soil beach community, and three different enclosed levels of recovery succession, as the research object. Used ecological method to measure vegetation species, biomass, coverage, important value and variety of eco-index in the various successional stages of community, while research content and ecological stoichiometry of the soil organic carbon, total nitrogen and total phosphorus.The following results were obtained:(1) Vegetation changes of communities in the three stages and four periods of alpine grassland degradation succession were:firstly, gramineae and Kobresia were the predominant species of community, had high ecological advantages. With the degradation succession of alpine grassland, aboveground biomass and coverage were decreased, important value of gramineae and Kobresia were gradually decreased, forbs began to invade the communities, important value of the forbs were increased, the number of species were increased, diversity index were increased, when the communities changed into forbs-black soil beach communities, forbs become the predominant species, native vegetation almost disappeared, biological diversity and evenness were decreased, communities structure become unitary. Function of ecology, production and life of alpine grassland were reduced.(2) The loss of soil nutrients, organic matter and total nitrogen content were decreased with succession and soil depth; Total phosphorus were decreased in the early stage of succession, and later did not change significantly; Soil organic matter, total N and C:N value showed a good correlation with the aboveground biomass scale.(3) The soil nutrients had a higher C:N ratio and low N:P ratio in degradation succession process of the alpine grassland, and had different the CNP ecological stoichiometry in different successional stages. It showed that the alpine degradation grassland performanced the limit of N in the succession process. Make sure the soil nutrient threshold of alpine degradation grassland were:C:N>10and N:P>8.(4) Grassland enclosure of alpine degradation grassland could significantly improve the aboveground biomass and coverage, could well improve the situation of grassland soil nutrients, improved soil organic matter, total nitrogen, total phosphorus, and played an important role in recovery and maintain of alpine grassland in Qinghai-Tibet Pleteau.更多还原