Record Display for the EPA National Library Catalog


OLS Field Name OLS Field Data
Main Title Analysis of Persistence in Model Ecosystems: Deterministic and Stochastic Food Web Models.
Author Gard, T. C. ;
CORP Author Georgia Univ., Athens. Dept. of Mathematics.;Environmental Research Lab., Athens, GA.
Year Published 1984
Report Number EPA-R80-7830; EPA-600/3-84-081;
Stock Number PB84-226984
Additional Subjects Toxicity ; Food chains ; Ecology ; Mathematical models ; Differential equations ; Growth ; Stochastic processes ; Nutrients ; Production ; Microcosms ; Ecosystems ; Predators
Library Call Number Additional Info Location Last
NTIS  PB84-226984 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 06/23/1988
Collation 15p
Mathematical models aid in understanding environmental systems and in developing testable hypotheses relevant to the fate and ecological effects of toxic substances in such systems. Within the framework of microcosm or laboratory ecosystem modeling, some differential equation models, in particular, become tractable to mathematical analysis when the focus is on the problem of persistence. In this report a microcosm-related, nutrient-producer-grazer, chemostat-chain model and general food web models are analyzed for persistence. The results, which take the form of inequalities involving model parameters, specify sufficient conditions for continued presence of the model components throughout indefinite time intervals. These results can serve as a basis for preliminary evaluations of model performance.