Pathogens and herbivores are key to diversity-productivity relationships. However, the extent to which plant diversity maintains higher productivity by reducing biomass loss from pathogens and herbivores remains unclear at the global scale. Based on a meta-analysis of 2315 observations from 316 studies, we show that, compared to monocultures, plant mixtures on average reduce pathogens abundance and damage to plants by 30.1% and 31.7% and those of invertebrate herbivores by 21.6% and 25.1%, while increasing plant productivity by 40.1% and 35.7%, respectively. Mixture effects on specialist pathogens and invertebrate herbivores become more negative with increasing plant taxonomic, functional, and phylogenetic diversity in mixtures, while those on generalist pathogens and invertebrate herbivores show no significant relationships with any diversity metrics. Mixture effects on pathogens decrease with stand age but those on invertebrate herbivores shift from negative to positive with stand age. Mixture effects on pathogens and invertebrate herbivores are negatively associated with those on productivity. Our findings highlight that conserving plant diversity could reduce biotic damage to plants and enhance global primary productivity.
Huang et al. (Tue,) studied this question.