PARENT SESSION
Poster Session 23: Soil Ecology
Wednesday, August 10, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Soil community feedbacks in an old-field model system.
Pendergast, Thomas*,1, Carson, Walter1, 1 University of Pittsburgh, Pittsburgh, PA, USA
ABSTRACT- Plant species culture belowground microbial communities that can have strong negative or positive effects on individual and population performance. The soil community feedback model predicts that differential responses of plant species to home and competitor soil communities can mediate plant persistence and abundance. Here we employed this theoretical framework to evaluate plant-microbial community relationships in an old-field model system by using plant performance as a bioassay. In a greenhouse pot experiment, five coexisting, perennial old-field plant species of varying abundance (2 Solidago spp., 3 Aster spp.) were grown in eight soil communities with two sterilization treatments, controlling for resource drawdown. Soil communities were obtained from replicated, long-term monocultures of old-field plants species. Results indicate that old field plant species do respond differentially to soil communities and sterilization treatments; biomass of Aster species was generally dependent on soil community, with significant increases in biomass in live vs. sterile soil, potentially indicating mutualist dependency. Aster pilosus had decreased growth in the soil community of the dominant competitor (S. canadensis), indicating negative feedback. Aster populations, therefore, may be subject to flux pending plant community composition and competitor identity. The Solidago species, however, were largely unresponsive to soil community or sterilization treatment, implying their abundance is not regulated by soil community processes. On-going experiments are testing the predictive ability of the soil community feedback model, the importance of these feedbacks relative to interspecific competition, and we are attempting to identify potential drivers of these pattern.
Key words: feedback, soil community, old-field, Solidago