Exploitation ecosystems in heterogeneous habitat complexes

Summary When the model of exploitation ecosystems by Oksanenet al. (1981) is re-analysed, using similar consumer-victim differential equations, but allowing dispersal between habitats differing in primary productivity, the relation between trophic dynamics and primary productivity turns out to be strongly dependent on the abundance relationships between different habitat types. In habitat complexes where a relatively productive habitat abounds, exploitation tends to spill over' to the barren habitat, whose trophic dynamics thus become to a high degree driven by the dynamics in the productive habitat and entirely different from the predictions of Oksanenet al. (1981). Conversely, in habitat complexes where the barren habitat overwhelmingly prevails, the spillover exploitation becomes strongly diluted. Consequently, local trophic dynamics within both habitats will behave approximately as predicted by the model of Oksanenet al. (1981).