Plant-soil feedback is shut down when nutrients come to town

Background and aimsThe concept of plant-soil feedback is increasingly used to explain plant community assembly processes. Soil nutrient availability can be expected to play a critical role on these processes. However, little is known about the effects of nutrient availability on feedback direction and strength.MethodsA plant-soil feedback experiment was performed with the grasses Anthoxanthum odoratum and Festuca rubra, and the forbs Leontodon hispidus and Plantago lanceolata, on soil with either low or high nutrient availability. Additionally, we tested if plant-soil feedback of the two forbs under these conditions changed by inoculation of the soil with spores of an arbuscular mycorrhizal fungus.ResultsIncreased nutrient availability neutralised plant-soil feedback based on shoot biomass independent of its negative or positive direction, whereas the effects on root biomass were either not altered or turned negative. Mycorrhizal fungi spore addition decreased negative feedback and increased positive feedback.ConclusionsOur results suggest that negative plant-soil feedback on low nutrient soil can be overcome with nutrient addition, and that positive soil biota associations on low nutrient soil may become superfluous with nutrient increase. We hypothesize that species-specific, microbial mediated plant community assembly processes occur in low rather than high nutrient environments.