OMNIVORY AS A STABILIZING FEATURE OF NATURAL COMMUNITIES

Omnivory-defined broadly as feeding on more than one trophic level-occ upies a prominent position in discussions of food web architecture and dynamics, due in large part to an enduring conflict regarding omnivor y's role in community dynamics, According to classical results from ma thematical food web theory, omnivory destabilizes ecological communiti es, whereas more recent conceptual syntheses suggest that omnivory sho uld be a strongly stabilizing factor in food webs. Working with an art hropod assemblage at Mount Saint Helens, I experimentally addressed th is controversy using a two-way factorial design that crossed a manipul ation of the degree of omnivory with another ''disturbance'' manipulat ion that targeted a specific component of the assemblage. In this stat istical design, significant interaction effects (i.e., how the communi ty impacts of the disturbance varied with the de ree of omnivory) iden tified key stabilizing or destabilizing influences of omnivory. Overal l, my experimental results indicated that increasing the degree of omn ivory stabilized community dynamics, in keeping with recent conceptual syntheses.