甘南高寒草甸植物群落物种多度分布特征

为分析甘南高寒草甸植物群落物种多度分布格局对海拔梯度的响应，探讨物种多样性的形成规律及维持机制，采用典型样地调查法采集数据信息，并通过RAD软件程序包对实验数据进行拟合分析.结果表明：植物群落物种多样性随海拔的升高呈现先增加后降低的“中间膨胀”模式，海拔3500m处群落物种多样性达到最大.利用5个模型对海拔梯度上全部物种多度分布进行拟合发现，甘南高寒草甸植物群落物种多度分布符合生态位模型，尤其是geo模型，利用该模型可以很好地拟合群落物种多度分布格局，同时也说明生态位分化对高寒草甸植物群落物种多度分布起主要作用.常见种多度分布的最优拟合模型为geo模型，其与全部物种的最优拟合模型一致；而稀有种多度分布的最优拟合模型为rane模型，说明常见种是影响不同海拔梯度群落物种多度分布格局的主要原因，其对群落生产力和稳定性的维持有不可替代的作用，但稀有种因其独特的功能性状也在一定程度上影响着群落结构，二者以各自不同的方式共同维系着高寒草甸的物种多样性.

Species abundance distribution characteristics of alpine meadow plant community in Gannan

The response of species abundance distribution (SAD) pattern of alpine meadow plant community to altitude gradient was analyzed, and the formation rule and maintenance mechanism of species diversity were discussed. In this paper, the typical sample plot survey method was used to collect data, and the experimental data were fitted and analyzed by RAD (rank abundance distribution) software package. The results showed that the species diversity of plant community showed a "Hump relationship" pattern with the increase of altitude, and reached the maximum at 3500m. Five models were used to fit the SAD on the altitude, it was found that the overall SAD of alpine meadow plant community was in line with the niche model, especially the geo. The model could be used to fit the distribution pattern of community species abundance, and it also showed that niche differentiation plays a major role in the SAD of alpine meadow plant community. The best fitting model of common SAD was geo, which was consistent with the best fitting model of overall species, while the best fitting model of rare SAD was rane. The above results showed that common species were the main factors affecting the SAD pattern of communities at different altitudes, and they played an irreplaceable role in maintaining the productivity and stability of communities. However, rare species also affected the community structure to a certain extent because of their unique functional characteristics, and they maintain the stability of species diversity of alpine meadow communities in different ways.