PARENT SESSION
Poster Session 11: Disturbance Ecology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Role of the diversity of soil microbial communities in their resistance and resilience following disturbances.
Le Roux, Xavier*,1, Wertz, Sophie1, Poly, Franck1, Prosser, James2, Freitag, Thomas2, Degrange, Valérie1, 1 Microbial Ecology Laboratory, Villeurbanne, France2 Department of Molecular and Cell Biology, Aberdeen, Scotland
ABSTRACT- Assessing the impact of natural and man-induced disturbances on ecosystem functioning, and more particularly ecosystem resistance and resilience following disturbances, is of increasing importance in ecology. However, to what extent the characteristics, and in particular the diversity, of microbial communities can mediate the response of key aspects of ecosystem functioning to disturbances remain largely unknown. We characterized the impact of decreasing the diversity of soil heterotrophic, denitrifying and nitrifying microbial communities on their resistance and resilience following disturbances. A species removal approach based on serial dilutions was used to reduce the diversity of the three communities. Sterile soil microcosms were inoculated with serial suspension/dilutions of the same non sterile soil and then incubated to allow recolonization (i.e. to obtain equivalent community sizes between dilutions). The microcosms were then submitted to a perturbation (heating: 42 degrees C during 24 h). The activity (i.e. carbon mineralization, denitrification and nitrification), size and diversity levels of each community were monitored before, immediately after perturbation to quantify resistance, and during 2 months after perturbation to quantify resilience. Molecular techniques at DNA level showed that dilution treatments induced a progressive reduction of the richness of heterotrophic, denitrifying and nitrifying communities. The resistance and resilience to the model disturbance differed between the three communities and between diversity levels for a given community. Our results are used to discuss to what extent microbial diversity needs to be taken into account in the context of ecosystem response to disturbances.
Key words: biodiversity, resistance, resilience, soil microbial functional groups