Complementarity in both plant and mycorrhizal fungal communities are not necessarily increased by diversity in the other

1. Higher species diversity can improve community performance within a species guild when different species complement each other in their use of the available niche, such as through resource partitioning. However, species in one guild of organisms may act as resources for another such that the diversity in one guild alters the realized niche for species in another. Yet, it remains largely untested as to whether diversity in one guild of organisms influences species complementarity in another. 2. The productivity and diversity in plant and arbuscular mycorrhizal (AM) fungal communities can be positively associated with each other through their typically mutualistic exchange of resources. Here we utilized these two interacting species guilds to determine whether greater diversity in one influences species complementarity in the other. This was done by creating monocultures and a mixture of a grass, forb, and legume in a full factorial design with monocultures and a mixture of four AM fun...