Document: JAM-3-92-21

Stoichiometry, herbivory, and competition for nutrients.

GROVER, J.P.*

University of Texas at Arlington, Arlington, TX 76019 USA ¹

Abstract:
When plant species compete for two nutrients and are grazed by herbivores, the relative sequestration of the two nutrients by the herbivores - their "stoichiometry" - is expected to influence competitive outcomes. This effect arises from differential recycling of the two nutrients by herbivores, and it is explored with simple Lotka-Volterra models, and with more realistic parameterized models. Variations in herbivore stoichiometry potentially produce the same range of competitive outcomes as arise from abiotic variations in relative nutrient supply. In some cases, predicted patterns of plant species dominance resemble the "resource-ratio" patterns seen in competition models without herbivores. Patterns of dominance and responses to enrichment also resemble other recent models of simultaneous plant competition and herbivory. Parameterized models of algae and zooplankton suggest that such stoichiometric effects occur under realistic conditions, and that planktonic herbivores are unlikely to mediate coexistence of competitors.

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This abstract is being presented at: 1:15 PM in session:
Oral Session #46: Modeling Populations and Statistical Ecology.