Chase Jonathan M
Department of Biology, Washington University, Campus Box 1137, St. Louis, MO 63130-4899, USA.
Oecologia. 2003 Aug;136(4):489-98. doi: 10.1007/s00442-003-1311-7. Epub 2003 Jun 26.
Community assembly provides a conceptual foundation for understanding the processes that determine which and how many species live in a particular locality. Evidence suggests that community assembly often leads to a single stable equilibrium, such that the conditions of the environment and interspecific interactions determine which species will exist there. In such cases, regions of local communities with similar environmental conditions should have similar community composition. Other evidence suggests that community assembly can lead to multiple stable equilibria. Thus, the resulting community depends on the assembly history, even when all species have access to the community. In these cases, a region of local communities with similar environmental conditions can be very dissimilar in their community composition. Both regional and local factors should determine the patterns by which communities assemble, and the resultant degree of similarity or dissimilarity among localities with similar environments. A single equilibrium in more likely to be realized in systems with small regional species pools, high rates of connectance, low productivity and high disturbance. Multiple stable equilibria are more likely in systems with large regional species pools, low rates of connectance, high productivity and low disturbance. I illustrate preliminary evidence for these predictions from an observational study of small pond communities, and show important effects on community similarity, as well as on local and regional species richness.
群落构建为理解决定特定地点存在哪些物种以及多少物种的过程提供了概念基础。有证据表明，群落构建通常会导致单一的稳定平衡，即环境条件和种间相互作用决定哪些物种将在那里存在。在这种情况下，具有相似环境条件的局部群落区域应具有相似的群落组成。其他证据表明，群落构建可导致多个稳定平衡。因此，即使所有物种都能进入群落，最终的群落仍取决于构建历史。在这些情况下，具有相似环境条件的局部群落区域在群落组成上可能非常不同。区域和局部因素都应决定群落构建的模式，以及具有相似环境的不同地点之间最终的相似程度或差异程度。在区域物种库较小、连通率高、生产力低和干扰大的系统中，更有可能实现单一平衡。在区域物种库大、连通率低、生产力高和干扰小的系统中，更有可能出现多个稳定平衡。我通过对小型池塘群落的观察研究来说明这些预测的初步证据，并展示其对群落相似性以及局部和区域物种丰富度的重要影响。
