DOI: 10.5061/dryad.fbg79cp3b
title: Interactive effects of leaf pathogens and plant mycorrhizal type on plant diversity–productivity relationships

description: 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.
description: # 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