稀有种和常见种对植物群落物种丰富度格局的相对贡献

The relative contributions of rare and common species to the patterns of species richness in plant communities

物种丰富度格局的形成不仅依赖于群落的构建过程,同样也依赖于群落中的物种组成(如稀有种和常见种)。本文以黄土高原子午岭林区的辽东栎(Quercus wutaishanica)林为研究对象,根据频度大小对物种进行排序,形成稀有–常见种和常见–稀有种两条物种序列,通过逐一添加(去除)物种,分析引起的总体物种丰富度及其成分(α多样性和β多样性)的变化,确定稀有种和常见种对物种丰富度格局的相对贡献。结果表明:(1)常见–稀有种序列与群落总体物种丰富度的相关性呈先剧增后平稳的对数增长曲线,而稀有–常见种序列与群落总体的相关性与前者刚好相反,呈先平稳后剧增的指数增长曲线;(2)α多样性在常见–稀有种序列中呈明显的对数变化曲线,而在稀有–常见种序列中呈指数增长曲线;(3)与α多样性变化相反,β多样性在常见–稀有种序列中随物种的进入先迅速降低后逐渐平稳,而在稀有–常见种序列中先平稳后急剧降低。可以看出,常见种不仅主导群落的总体物种丰富度格局,同时也是α多样性和β多样性格局的重要贡献者。因此,常见种是群落物种丰富度格局的指示者,也应该是优先保护的物种。

Understanding how overall patterns of spatial variation in species richness are affected by species distributional is one of the key questions in species diversity research. In the present study, we investigated the relative contributions of common and rare species to overall plant species richness in the Liaodong oak（Quercus wutaishanica） forest, which is located in the Ziwu Mountains of Loess Plateau, northwestern China. Based on species frequency distribution, we developed rank sequences of the most common to the most rare and the most rare to the most common species. We then correlated the rank sequences with cumulative species distributions. Our results showed that common species had a higher correlation with the cumulative species distribution in comparison with rare species. Moreover, common species had stronger effects on species α diversity and species β diversity as compared with rare species. Although the number of rare species was greater than that of common species, the overall species richness pattern was better predicted by common species than rare species. Therefore, common species were confirmed to be good indicators of species richness pattern and need to be protected priority.