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...