Gillman Len N, Wright Shane D
Division of Applied Science, AUT University, Auckland, New Zealand.
Ecology. 2006 May;87(5):1234-43. doi: 10.1890/0012-9658(2006)87[1234:tiopot]2.0.co;2.
Despite much scrutiny the relationship between productivity and species richness remains controversial, and there is little agreement about causal processes. We present the results of a survey of 159 productivity-plant species richness (P-PSR) relationships from 131 published studies. We critically assessed each study with respect to experimental design and for the appropriateness of the surrogates used for productivity. We were able to accept only 60 of the reported relationships as robust tests of the P-PSR relationship and a further 18 as robust tests of the biomass species richness relationship. Previous analyses have found that unimodal P-PSR relationships predominate. In contrast, we found that, in studies that used data of continental to global extent, all P-PSR relationships were positive regardless of grain, that almost all were also positive in data sets of regional extent, and that unimodal relationships were not dominant even in studies of fine grain or small spatial extent. Our results differ substantially from previous meta-analyses because previous studies have included a large number of studies that do not meet basic experimental design criteria for objectively testing P-PSR relationships. These results have important implications for theory that attempts to explain species richness patterns. We critically review four dominant theories in light of our results and develop new falsifiable predictions of relationship from these theories at both small and large spatial scales.
尽管经过了大量审视，但生产力与物种丰富度之间的关系仍存在争议，对于因果过程也几乎没有共识。我们展示了一项对131项已发表研究中的159个生产力 - 植物物种丰富度（P - PSR）关系的调查结果。我们严格评估了每项研究的实验设计以及用于生产力的替代指标的适用性。我们仅能接受60个所报告的关系作为对P - PSR关系的有力检验，另外18个作为对生物量物种丰富度关系的有力检验。先前的分析发现单峰P - PSR关系占主导。相比之下，我们发现，在使用大陆到全球范围数据的研究中，无论粒度如何，所有P - PSR关系都是正相关的；在区域范围的数据集中，几乎所有关系也都是正相关的；即使在细粒度或小空间范围的研究中，单峰关系也不占主导。我们的结果与先前的荟萃分析有很大不同，因为先前的研究纳入了大量不符合客观检验P - PSR关系基本实验设计标准的研究。这些结果对试图解释物种丰富度模式的理论具有重要意义。我们根据研究结果对四种主导理论进行了批判性审视，并从这些理论出发，在小空间尺度和大空间尺度上提出了关于关系的新的可证伪预测。
