Changes in plant species composition through biodiversity loss can alter how species compete with one another. Recent research has shown that long-term maintenance of low- and high-diversity plant communities leads to selection of plants specifically adapted to the corresponding plant diversity. The selection for different types in differing diversity environments is presumed to have occurred by the sorting out of genotypes from large initial standing variation. Although negative soil feedbacks likely incur pathogen-induced selection pressure in plant monocultures, the potentially counteracting role of symbiosis between plants and arbuscular mycorrhizal fungi (AMF) is not well known.
We tested the growth responses of low- and high-diversity adapted plants to different AMF communities using progeny of eight grassland plant species that had undergone 12 years of selection in either monocultures (monoculture types) or mixtures (mixture types) in a biodiversity experiment. Plants were grown in a glass-house on sterile soil that we inoculated with (1) AMF extracted from the corresponding plant monocultures or (2) mixtures, (3) an externally produced ubiquitous AMF, Rhizoglomus irregulare, or (4) no AMF.
Results/Conclusions
We show that AMF communities from plant mixtures were on average more beneficial to plant biomass production than AMF communities from plant monocultures. Moreover, mixture-type plants, in contrast to monoculture-type plants, were on average more dependent on the AMF extracted from the field site of the biodiversity experiment. However, the dependency on generalist AMF R. irregulare did not differ between mixture and monoculture types. These results suggest that co-evolution of AMF and host plant results in a more beneficial mutualism in diverse plant communities in comparison with monocultures. This may influence the competitive ability of host plants in diverse plant communities demonstrating that changes in species composition may have cascading selection pressure on associated trophic groups of species.