Interactive effects of leaf pathogens and plant mycorrhizal type on plant diversity–productivity relationships
Abstract
Diversity–productivity relationships can differ between forests dominated by different mycorrhizal types and be modulated by specialist and generalist pathogens. However, little is known about how these factors interact to modulate biodiversity effects. We addressed this knowledge gap with a 2-year experiment combining the manipulation of plant richness (1, 2, 4, 8 species) and mycorrhizal type (arbuscular mycorrhizal [AM] tree-dominated; ecto-mycorrhizal [ECM] tree-dominated) with fungicide application (added or control). Biodiversity effects were quantified for community productivity and its two components (shoots and roots). We observed non-linear diversity-productivity relationships, with productivity of ECM-tree dominated communities increasing at low to intermediate diversity and declining at the highest species richness. Fungicide application reduced positive complementarity effects and increased productivity in both ECM tree monocultures as well as 8-species mixtures. This finding suggests that dilution effects of specialised pathogens may dominate at low diversity, while the spillover effects of generalist pathogens may become dominant at high diversity, resulting in unimodal diversity-productivity relationships. In AM tree-dominated communities, aboveground productivity strongly increased in response to leaf pathogen suppression in 8-species mixtures, and the release from leaf pathogens benefited most the species that were most productive in fungicide-treated monocultures. This agrees with the prediction that spillover effects of generalist pathogens in diverse plant communities could differentially supress highly productive species due to the trade-off between growth and defence. In addition, positive biodiversity effects on root production were significantly stronger in AM-tree that ECM-tree dominated communities. Our results demonstrate that relationships between plant diversity and productivity can be non-linear due to combined effects of specialised and generalised plant-fungal interactions, depend on plant mycorrhizal type and differ between aboveground and belowground compartments.
README: Interactive effects of leaf pathogens and plant mycorrhizal type on plant diversity–productivity relationships
Description of the Data and file structure
This dataset was collected on the basis of an experiment testing the interactive effects of leaf pathogens and mycorrhizal type on plant diversity-productivity relationships. The aim of this study was to address how diversity-productivity relationships are regulated by pathogens and plant mycorrhizal type. The experiment was a full-factor design, with three factors: fungicide treatment (fungicide addition, control), mycorrhizal type of plant community (AM tree-dominated, ECM tree-dominated), and species richness (species number in each community, 1, 2, 4, 8). The experiment was conducted for two years, and at harvest, plant dry biomass was weighed. "No." indicates the number of each pot, and "composition" refers to the species composition within each pot, with each value representing a unique composition. RS = root: shoot ratio, shoot = shoot biomass (g), root = root biomass, total = total biomass