title: Do interactions between plant and soil biota change with elevation? A study on Fagus sylvatica.
abstract: Theoretical models predict weakening of negative biotic interactions and strengthening of positive interactions with increasing abiotic stress. However, most empirical tests have been restricted to plant-plant interactions. No empirical study has examined theoretical predictions of interactions between plants and below-ground micro-organisms, although soil biota strongly regulates plant community composition and dynamics. We examined variability in soil biota effects on tree regeneration across an abiotic gradient. Our candidate tree species was European beech (Fagus sylvatica L.), whose regeneration is extremely responsive to soil biota activity. In a greenhouse experiment, we measured tree survival in sterilized and non-sterilized soils collected across an elevation gradient in the French Alps. Negative effects of soil biota on tree survival decreased with elevation, similar to shifts observed in plant-plant interactions. Hence, soil biota effects must be included in theoretical models of plant biotic interactions to accurately represent and predict the effects of abiotic gradient on plant communities.
authors.affiliation: Cemagref, U.R. Ecosystèmes Montagnards, 2 rue de la Papeterie, 38402 St-Martin-d'Heres, France. emmanuel.defossez@cemagref.fr
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Defossez
authors.forename: Benoît
authors.initials: B
authors.lastname: Courbaud
authors.forename: Benoît
authors.initials: B
authors.lastname: Marcais
authors.forename: Wilfried
authors.initials: W
authors.lastname: Thuiller
authors.forename: Elena
authors.initials: E
authors.lastname: Granda
authors.forename: Georges
authors.initials: G
authors.lastname: Kunstler
mesh_terms: D000531:Altitude; D029964:Fagus / Q000502:physiology*; D012988:Soil Microbiology