Diversity and identity of economics traits determine the extent of tree mixture effects on ecosystem productivity

1. Although both observational and experimental studies have shown that positive tree species diversity-productivity relationships are predominant in global forests, weak or the lack of tree species diversity and productivity relationships also exist. Growing evidence has revealed that ecosystem productivity depends more on the functional characteristics of species than on their number. However, exactly to what extent tree diversity effects on ecosystem productivity are influenced by the variability and composition of functional traits have been rarely tested both across and at given species richness levels. 2. Here, we employed a meta-analysis of global-scale data from 59 tree diversity experiments to examine how the diversity and community-weighted means of economics traits determine the outcomes of tree mixture effects on productivity across and within species richness levels. 3. We found that the positive effects of tree mixtures on productivity were strengthened by the increasing m...1. 尽管野外观测研究与控制实验均已证实，全球森林中树木物种多样性-生产力正向关系占据主导地位，但树木物种多样性与生产力关系微弱乃至缺失的情况亦普遍存在。日益增多的研究证据表明，生态系统生产力更多取决于物种的功能性状（functional traits），而非物种数量本身。然而，在不同物种丰富度梯度及给定物种丰富度水平下，功能性状的变异与组成如何影响树木多样性对生态系统生产力的效应，这一科学问题迄今仍鲜有研究得到验证。 2. 本研究针对来自59项树木多样性控制实验的全球尺度数据开展元分析（meta-analysis），旨在解析物种多样性与资源经济学性状（economics traits）的群落加权均值（community-weighted means），如何在不同及给定物种丰富度水平下调控树木混交对生态系统生产力的效应结果。 3. 研究发现，树木混交对生产力的正向效应会随着...（原文未完结）