Institute for Botany, University of Cologne, Cologne, Germany.
PLoS One. 2011;6(7):e21972. doi: 10.1371/journal.pone.0021972. Epub 2011 Jul 6.
The study of the interrelationship between productivity and biodiversity is a major research field in ecology. Theory predicts that if essential resources are heterogeneously distributed across a metacommunity, single species may dominate productivity in individual metacommunity patches, but a mixture of species will maximize productivity across the whole metacommunity. It also predicts that a balanced supply of resources within local patches should favor species coexistence, whereas resource imbalance would favor the dominance of one species. We performed an experiment with five freshwater algal species to study the effects of total supply of resources, their ratios, and species richness on biovolume production and evenness at the scale of both local patches and metacommunities. Generally, algal biovolume increased, whereas algal resource use efficiency (RUE) and evenness decreased with increasing total supply of resources in mixed communities containing all five species. In contrast to predictions for biovolume production, the species mixtures did not outperform all monocultures at the scale of metacommunities. In other words, we observed no general transgressive overyielding. However, RUE was always higher in mixtures than predicted from monocultures, and analyses indicate that resource partitioning or facilitation in mixtures resulted in higher-than-expected productivity at high resource supply. Contrasting our predictions for the local scale, balanced supply of resources did not generally favor higher local evenness, however lowest evenness was confined to patches with the most imbalanced supply. Thus, our study provides mixed support for recent theoretical advancements to understand biodiversity-productivity relationships.
生产力和生物多样性之间的相互关系研究是生态学中的一个主要研究领域。理论预测，如果基本资源在集合群落中不均匀分布，单一物种可能会在单个集合群落斑块中主导生产力，但物种的混合将使整个集合群落的生产力最大化。它还预测，局部斑块内资源的平衡供应应该有利于物种共存，而资源失衡则有利于一个物种的优势。我们用五种淡水藻类进行了一项实验，以研究资源总量、它们的比例和物种丰富度对生物量生产和局部斑块以及集合群落尺度均匀度的影响。一般来说，在含有所有五种物种的混合群落中，随着资源总量的增加，藻类生物量增加，而藻类资源利用效率（RUE）和均匀度降低。与生物量生产的预测相反，在集合群落尺度上，物种混合物并不总是优于所有的单培养物。换句话说，我们没有观察到一般的过度生产力。然而，RUE 在混合物中总是高于从单培养物预测的值，并且分析表明混合物中的资源分配或促进作用导致在高资源供应下产生高于预期的生产力。与我们对局部尺度的预测相反，资源的平衡供应并不总是有利于更高的局部均匀度，但最低的均匀度仅限于资源供应最不平衡的斑块。因此，我们的研究为理解生物多样性与生产力关系的最新理论进展提供了混合支持。
