title: Natural regulation of herbivorous forest insect populations.
abstract: From basic principles of positive/negative feedback control and classical density-dependent/independent population theory we outline a general explanation for the regulation of herbivore populations in forested ecosystems. We identify three fundamental patterns of behavior; (i) populations regulated close to equilibrium ("tight" regulation) by fast-acting negative feedback processes, (ii) populations regulated by delayed negative feedback processes ("loose" regulation) which often exhibit wide-amplitude density cycles, and (iii) populations characterized by positive feedback processes over certain density ranges that may exhibit divergent (metastable) behavior. We then discuss the effects of these different kinds of herbivore population behavior on the dynamics of forest ecosystems and explore some elemental models of herbivore/forest interactions. Finally, using the spruce bark beetle, Ips typographus, as an example, we demonstrate how the theory can be used to explain the dynamics of specific herbivore populations and to develop general strategies for managing destructive herbivore outbreaks.
authors.affiliation: Department of Entomology, Washington State University Pullman, 99164-6432, WA, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Berryman
authors.affiliation: Department of Biology, Division of Zoology, University of Oslo, Norway.
authors.forename: N Chr
authors.initials: NC
authors.lastname: Stenseth
authors.affiliation: V. N. Sukachev Institute of Forest and Wood, 660036, Krasnoyarsk, USSR.
authors.forename: A S
authors.initials: AS
authors.lastname: Isaev
keywords: Cycles; Equilibrium; Herbivorous insects; Metastability; Natural regulation