title: Soil fungal pathogens and the relationship between plant diversity and productivity.
abstract: One robust result from many small-scale experiments has been that plant community productivity often increases with increasing plant diversity. Most frequently, resource-based or competitive interactions are thought to drive this positive diversity-productivity relationship. Here, we ask whether suppression of plant productivity by soil fungal pathogens might also drive a positive diversity-productivity relationship. We created plant assemblages that varied in diversity and crossed this with a ± soil fungicide treatment. In control (non-fungicide treated) assemblages there was a strong positive relationship between plant diversity and above-ground plant biomass. However, in fungicide-treated assemblages this relationship disappeared. This occurred because fungicide increased plant production by an average of 141% at the lower ends of diversity but boosted production by an average of only 33% at the higher ends of diversity, essentially flattening the diversity-productivity curve. These results suggest that soil pathogens might be a heretofore unappreciated driver of diversity-productivity relationships.
authors.affiliation: Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA. john.maron@mso.umt.edu
authors.forename: John L
authors.initials: JL
authors.lastname: Maron
authors.forename: Marilyn
authors.initials: M
authors.lastname: Marler
authors.forename: John N
authors.initials: JN
authors.lastname: Klironomos
authors.forename: Cory C
authors.initials: CC
authors.lastname: Cleveland
mesh_terms: D044822:Biodiversity; D018533:Biomass; D005658:Fungi / Q000502:physiology*; D054884:Host-Pathogen Interactions; D018521:Plant Physiological Phenomena; D012988:Soil Microbiology