Atwater Daniel Z, Callaway Ragan M
Ecology. 2015 Dec;96(12):3332-42. doi: 10.1890/15-0889.1.
Plant diversity enhances many ecosystem processes, including productivity, but these effects have been studied almost exclusively at the taxonomic scale of species. We explore the effect of intraspecific diversity on the productivity of a widespread and dominant grassland species using accessions collected from populations throughout its range. We found that increasing population/ecotype diversity of Pseudoroegneria spicata increased productivity to a similar degree as that reported for species diversity. However, we did not find evidence that overyielding was related to either resource depletion or to pathogenic soil fungi, two causes of overyielding in species-diverse communities. Instead, larger accessions overyielded at low diversity at the expense of smaller accessions, and small accessions overyielded through complementarity at all levels of diversity. Furthermore, overyielding was stronger for accessions from mesic environments, suggesting that local adaptation might predictably influence how plants respond to increases in diversity. This suggests that mass-based competition or other cryptic accession-specific processes had complex but important effects on overyielding. Our results indicate that the effects of diversity within a species can be substantial but that overyielding by intraspecifically diverse populations may not be through the same processes thought to cause overyielding in species diverse communities.
植物多样性增强了许多生态系统过程，包括生产力，但这些影响几乎仅在物种的分类学尺度上进行了研究。我们利用从其分布范围内的种群收集的材料，探讨种内多样性对一种广泛分布且占主导地位的草原物种生产力的影响。我们发现，增加穗序假鹅观草的种群/生态型多样性，其生产力提高的程度与物种多样性所报告的相似。然而，我们没有发现超产与资源耗竭或致病土壤真菌有关的证据，而这两者是物种丰富群落中超产的两个原因。相反，在低多样性水平下，较大的材料超产是以较小的材料为代价的，而小材料则通过在所有多样性水平上的互补作用实现超产。此外，来自中生环境的材料超产更强，这表明局部适应可能会可预测地影响植物对多样性增加的反应。这表明基于质量的竞争或其他隐秘的特定材料过程对超产有复杂但重要的影响。我们的结果表明，一个物种内的多样性影响可能很大，但种内多样种群的超产可能不是通过与物种多样群落中超产相同的过程实现的。
