Understanding the relationship between stand-level tree diversity and productivity has the potential to inform the science and management of forests. History shows that plant diversity-productivity relationships are challenging to interpret—and this remains true for the study of forests using non-experimental field data. Here we highlight pitfalls regarding the analyses and interpretation of such studies. We examine three themes: 1) the nature and measurement of ecological productivity and related values; 2) the role of stand history and disturbance in explaining forest characteristics; and 3) the interpretation of any relationship. We show that volume production and true productivity are distinct, and neither is a demonstrated proxy for economic values. Many stand characteristics, including diversity, volume growth and productivity, vary intrinsically with succession and stand history. We should be characterising these relationships rather than ignoring or eliminating them. Failure to do so may lead to misleading conclusions. To illustrate, we examine the study which prompted our concerns —Liang et al. (Science 354:aaf8957, 2016)— which developed a sophisticated global analysis to infer a worldwide positive effect of biodiversity (tree species richness) on “forest productivity” (stand level wood volume production). Existing data should be able to address many of our concerns. Critical evaluations will improve understanding.

中文翻译：

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解释森林多样性与生产力的关系：体积值，干扰历史和替代推论

了解林木水平多样性与生产力之间的关系有可能为森林科学和管理提供信息。历史表明，植物多样性与生产力的关系难以解释，而对于使用非实验性田间数据进行森林研究仍然如此。在这里，我们强调了有关此类研究的分析和解释的陷阱。我们研究了三个主题：1）生态生产力的性质和度量以及相关价值；2）林分历史和干扰在解释森林特征中的作用；和3）任何关系的解释。我们表明，批量生产和真实生产率是截然不同的，并且都不能证明经济价值。许多林分的特征，包括多样性，产量增长和生产力，继任和展台历史本质上会有所不同。我们应该刻画这些关系的特征，而不是忽略或消除它们。否则可能会导致误导性结论。为了说明这一点，我们检查了引起我们关注的研究-Liang等。（科学354：aaf8957，2016）—该研究开展了复杂的全球分析，以推断生物多样性（树种丰富度）对“森林生产力”（标准木材产量）的全球积极影响。现有数据应该能够解决我们的许多问题。批判性评估将增进理解。我们研究了引起我们关注的研究-Liang等。（科学354：aaf8957，2016）—该研究开展了复杂的全球分析，以推断生物多样性（树种丰富度）对“森林生产力”（标准木材产量）的全球积极影响。现有数据应该能够解决我们的许多问题。批判性评估将增进理解。我们研究了引起我们关注的研究-Liang等。（科学354：aaf8957，2016）—该研究开展了复杂的全球分析，以推断生物多样性（树种丰富度）对“森林生产力”（标准木材产量）的全球积极影响。现有数据应该能够解决我们的许多问题。批判性评估将增进理解。