... Richter-Dyn ( 197 4), May ( 197 4), Ginzburg et al. ( 198 2), Iwasa ( 199 8), Tanaka ( 199 8), Hakoyama and Iwasa ( 199 9)Stressor: Any stressor whose impacts can be summarized as a change in the mean or variance ... sparseModel: Stochastic Discrete-Time ModelsReferences: Poole ( 197 4), Capocelli and Ricciardi ( 197 4), Goel and Richter-Dyn ( 197 4), May ( 197 4), Ginzburg et al. ( 198 2), Ferson ( 199 9)Stressor: Any stressor ... discrete or continuous-time) and deterministic life-history matrix models are most appropriate for screening-level ecolog - ical risk assessments (Table 13.1). Some simple food-web models, founded...