title: Allowing variance may enlarge the safe operating space for exploited ecosystems.
abstract: Variable flows of food, water, or other ecosystem services complicate planning. Management strategies that decrease variability and increase predictability may therefore be preferred. However, actions to decrease variance over short timescales (2-4 y), when applied continuously, may lead to long-term ecosystem changes with adverse consequences. We investigated the effects of managing short-term variance in three well-understood models of ecosystem services: lake eutrophication, harvest of a wild population, and yield of domestic herbivores on a rangeland. In all cases, actions to decrease variance can increase the risk of crossing critical ecosystem thresholds, resulting in less desirable ecosystem states. Managing to decrease short-term variance creates ecosystem fragility by changing the boundaries of safe operating spaces, suppressing information needed for adaptive management, cancelling signals of declining resilience, and removing pressures that may build tolerance of stress. Thus, the management of variance interacts strongly and inseparably with the management of resilience. By allowing for variation, learning, and flexibility while observing change, managers can detect opportunities and problems as they develop while sustaining the capacity to deal with them.
authors.affiliation: Center for Limnology, University of Wisconsin-Madison, Madison, WI 53706; srcarpen@wisc.edu.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Carpenter
authors.affiliation: Department of Economics, University of Wisconsin-Madison, Madison, WI 53706; Department of Economics, University of Missouri, Columbia, MO 65211;
authors.forename: William A
authors.initials: WA
authors.lastname: Brock
authors.affiliation: Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, and Stockholm Resilience Centre, Stockholm University, SE104 05 Stockholm, Sweden;
authors.forename: Carl
authors.initials: C
authors.lastname: Folke
authors.affiliation: Department of Aquatic Ecology and Water Quality Management, Wageningen University, NL-6700 AA Wageningen, The Netherlands.
authors.forename: Egbert H
authors.initials: EH
authors.lastname: van Nes
authors.affiliation: Department of Aquatic Ecology and Water Quality Management, Wageningen University, NL-6700 AA Wageningen, The Netherlands.
authors.forename: Marten
authors.initials: M
authors.lastname: Scheffer
mesh_terms: D020387:Food Chain; D008954:Models, Biological
keywords: adaptive management; critical transition; ecosystem; resilience; variance