| 摘要: |
| 【目的】探讨青海湟源冷、暖季放牧草地植被的物种组成、物种多样性及空间分布等植物群落特征的基本变化规律，以期为我国西部干旱、半干旱天然草原以及高寒草甸草原物种多样性的恢复、生产力的提高及山地草甸草原生态系统的保护提供参考。【方法】于2009-08-16-19进行野外调查，首先在冷、暖季放牧草地内有代表性的地段上各拉1条50 m的样线，然后沿着样线摆放100个50 cm×50 cm的大样方，再将每个大样方细分为4个25 cm×25 cm的小样方，记录小样方内出现的植物种，统计植物种数，采用β-二项分布模型进行数据解析，计算冷、暖季放牧草地植物种的出现频率、物种多样性指数和空间异质性指数。【结果】（1）检验结果表明，冷、暖季放牧草地的主要组成植物种对β-二项分布模型具有很好的吻合性。（2）冷季放牧草地的总物种数比暖季放牧草地多6种，冷季放牧草地大样方内的平均物种数、物种多样性指数均极显著高于暖季放牧草地。（3）在暖季实施围栏封育的冷季放牧草地，草地早熟禾（Poa pratensis）、垂穗披碱草（Elymus nutans）、小嵩草（Kobresia pygmaea）等优质牧草增加，而在暖季放牧草地，草地退化的标志性植物鹅绒萎陵菜（Potentilla anserina）和车前（Plantago asiatica）成为主要优势种，物种多样性降低。（4）冷季放牧草地的群落整体空间异质性高于暖季放牧草地。【结论】在暖季实施围栏封育而在冷季进行放牧利用的冷季放牧草地物种数、物种多样性、空间异质性增加，优质牧草种类增加，所以在生产实践中，应尽量避开牧草的生长季节而实行冷季放牧。 |
| 关键词: 放牧草地 β-二项分布 物种多样性 空间异质性 |
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| 基金项目:2008西北农林科技大学引进人才科研启动基金项目（01140413）；国家科技支撑计划项目（2011BAD17B05）；农业部公益性行业专项（200903060） |
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| Community characteristics of cold-season and warm-season grazing grasslands in Huangyuan,Qinghai,China |
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| Abstract: |
| 【Objective】The experiment was conducted in the warm-season and cold-season grazing grasslands in Huangyuan,Qinghai.We obtained information on the fundamental differences in community characteristics,such as vegetation composition,species diversity,and species spatial distributions,under two different grazing conditions in a montane meadow.We hope that the study can contribute to the recovery of species diversity and productivity gains of natural grasslands in the arid,semi-arid areas,and alpine meadows of western China in addition to providing protection for the montane meadow ecosystems is one of our aims.【Method】Field surveys were conducted from August 16 to 19,2009.First,we established a survey plot with 100 quadrats of 50 cm×50 cm along a 50 m transect in the grasslands and divided each of these quadrats into four small quadrats;then,we recorded all plant species within each small quadrat,the total number of plants,analyzed the data by the beta-binomial distribution model,calculated the occurrence frequency of plant species and the index of both species diversity and spatial heterogeneity in the cold-season and warm-season grazing grasslands.【Result】(1)The chi-square test showed that both warm-season and cold-season surveys fitted the beta binomial distribution model very well and that the data could be analyzed using this method.(2) Six more species were found in the cold-season grazing grassland than in the warm-season grazing grassland.In the cold-season grazing grassland,the average number of species and species diversity index within the quadrats was significantly higher than that in the warm-season grazing grassland.(3) In the cold-season grazing grassland,Poa pratensis,Elymus nutans,Kobresia pygmaea,and other high-quality forage species increased,due to protection by fencing,while in the warm-season grazing grassland,degraded species such as Potentilla anserina and Plantago asiatica became dominant and species diversity decreased.(4) Overall,the spatial heterogeneity in the cold-season grazing grassland was higher than that in the warm-season grazing grassland.【Conclusion】In the cold-season grazing grassland,due to protection by fencing,the average number of species,species diversity,spatial heterogeneity and quality forage species all increased,so it is better to graze in the cold-seasoning but not in the grass growing season in the production practice. |
| Key words: grazing grassland β-binomial distribution species diversity spatial heterogeneity |
