Stanley Harpole W, Tilman David
Ecol Lett. 2006 Jan;9(1):15-23. doi: 10.1111/j.1461-0248.2005.00836.x.
Although the distribution of plant species abundance in a Minnesota grassland was consistent with neutral theory, niche but not neutral mechanisms were supported by the ability of species traits to predict species abundances in three experimental grassland communities. In particular, data from 27 species grown in monoculture showed that species differed in a trait, R*, which is the level to which each species reduced the concentration of soil nitrate, the limiting soil nutrient and which is predicted to be inversely associated with competitive ability for nitrogen (N). In these N-limited habitats, species abundance ranks correlated with their predicted competitive ranks: low R* species, on average dominated. These correlations were significantly different than expected for neutral theory, which assumes the exchangeability of species traits. Additionally, we found that changes in relative abundance after environmental change (N-addition or disturbance) were not neutral but also were significantly associated with R*.
尽管明尼苏达州一片草原上植物物种丰度的分布与中性理论一致，但物种性状预测三个实验性草原群落中物种丰度的能力支持了生态位而非中性机制。具体而言，27种单作植物的数据表明，物种在一个名为R的性状上存在差异，R是指每个物种降低土壤硝酸盐浓度的水平，土壤硝酸盐是限制土壤养分，预计与氮（N）的竞争能力呈负相关。在这些氮受限的栖息地中，物种丰度排名与其预测的竞争排名相关：平均而言，低R物种占主导地位。这些相关性与中性理论预期的显著不同，中性理论假设物种性状具有可交换性。此外，我们发现环境变化（添加氮或干扰）后相对丰度的变化并非中性，而是也与R显著相关。
