高寒草甸不同黄帚橐吾密度斑块的植物群落结构特征

为了解黄帚橐吾（Ligularia virgaurea）斑块植物群落维持和演替过程，本研究以不同密度黄帚橐吾微斑块为研究对象，根据密度等级设置6个斑块梯度（D0，D1，D2，D3，D4和D5），分析不同斑块草地群落结构及生产力的变化特征。结果表明：随着黄帚橐吾密度的增加，禾本科和莎草科重要值明显降低，黄帚橐吾逐渐成为建群种；物种多样性指数呈先增加后降低趋势，且在D1~D2之间香农维纳指数、均匀度指数和优势度指数均为最高值；去除黄帚橐吾后的总地上生物量表现为D1显著高于D5（P<0.05），禾本科、莎草科和豆科植物的地上生物量为D4最高，杂类草生物量为D1显著高于D3~D5（P<0.05）；总地下生物量和0~10 cm土层的地下生物量变化趋势一致，为D1显著高于D4（P<0.05），10~20 cm土层的地下生物量随密度的增大呈显著增加趋势（P<0.05）。因此，当黄帚橐吾的密度介于D1~D2时，对草地稳定性的维持具有积极作用。

Characteristics of Plant Community Structure of Different Ligularia virgaurea Density Patches in Alpine Meadow

In order to understand the process of maintenance and succession of Ligularia virgaurea community patches, the micropatches of L.virgaurea with different densities were studied. According to the density level, the characteristics of grassland community structure and productivity of 6 density gradients of L.virgaurea micropatches (D0, D1, D2, D3, D4 and D5) were analyzed. The results showed that the importance values of Gramineae and Cyperaceae decreased significantly with the increase of L.virgaurea density, and L.virgaurea gradually became the constructive species. The species diversity index of each patch increased firstly and then decreased with the increase of L.virgaurea density, and the Shannon Wiener index, Pielou index and Simpson index reached the highest values between D1 and D2. The total aboveground biomass of D1 was significantly higher than that of D5 after removing L.virgaurea (P<0.05). The aboveground biomass of Gramineae, Cyperaceae and Leguminosae reached the maximum at D4, and the biomass of Forbs D1 was significantly higher than that of D3~D5 (P<0.05). The change trend of total underground biomass was consistent with that of 0~10 cm soil layer, D1 was significantly higher than D4 (P<0.05), and the underground biomass of 10~20 cm soil layer significantly increased with the increase of density (P<0.05). Therefore, when the density of L.virgaurea was between D1~D2, it played a positive role in maintaining grassland stability.