甘南亚高寒草甸稀有种对物种多样性和物种多度分布格局的贡献

稀有种不仅影响群落的物种多度分布格局, 同时也是α多样性的重要贡献者。本研究主要通过加性分配和Fortran软件的RAD程序包拟合的方法, 研究了甘南亚高寒草甸不同坡向物种多样性及多度分布格局的变化, 分析了物种多度分布格局及其α多样性的变化特征, 确定了稀有种在物种多度分布格局中的相对贡献。结果表明: (1)在南坡到北坡的变化中, 环境因子差异比较明显, 其中, 土壤全磷、有机碳、速效磷、碳氮比及含水量呈递增趋势; 土壤氮磷比和pH值呈递减趋势; 土壤全氮在西坡显著低于其他坡向, 而速效氮在所有坡向上差异不显著。(2)稀有种对群落物种多样性的影响在南-北坡向梯度上依次增大, 去除稀有种的影响在各坡向均高于去除非稀有种, 可见, 稀有种在甘南亚高寒草甸物种多样性中的相对贡献高于非稀有种。(3)各坡向的稀有种资源获取模式以随机分配占领模式(random fraction模型)为主, 而非稀有种则以生态位优先占领模式(geometric series模型)为主。由于稀有种有较大的扩散率, 在物种多样性较高的生态系统中, 物种之间的生态位重叠会更加明显, 从而抑制物种多样性的增加, 因此能达到维持原有物种多样性的目的。

Contribution of rare species to species diversity and species abundance distribution pattern in the Gannan subalpine meadow

Rare species not only contribute to a community’s species abundance distribution pattern, but are also important contributors to alpha diversity. In this study, we studied the changes of species diversity and species abundance distribution pattern in the subalpine meadow of Gannan at different slope directions. To do this, we used means of additive allocation and RAD package of Fortran software fitting to analyze species abundance distribution pattern and α diversity to determine the contribution of rare species in species abundance distribution pattern. The results show that: (1) From southern to northern slopes, environmental factors changed greatly as the total soil phosphorus, soil organic carbon, available phosphorus, carbon-nitrogen ratio and water content increased. The ratio of nitrogen to phosphorus and soil pH showed decreasing trends. Soil total nitrogen was significantly lower in the west slope than in other slope directions, while available nitrogen has no significant difference in all aspects. (2) The influence of rare species on the community’s species diversity increased from south to north. However, compared with the scenarios of removing rare species and the condition of removing non-rare species, the effect of removing rare species in all aspects was higher than that of removing non-rare species. Therefore, the relative contribution of rare species to species diversity was higher than that of non-rare species. (3) The resource acquisition strategy of rare species was found to be random (the random fraction). However, the niche preemption model (the geometric series) is the main model for non-rare species. Due to the large dispersal capacity of rare species, the niche overlap among species will be more obvious in the communities with high species diversity. In this way, the increase of species diversity is inhibited, thus maintaining the biodiversity.