Multiple Stable States and Catastrophic Shifts in Ecosystems

by

Sonia Kéfi

• LAST REVIEWED: 26 June 2019
• LAST MODIFIED: 26 June 2019
• DOI: 10.1093/obo/9780199830060-0219

Introduction

The idea that ecosystems may have multiple alternative stable states dates back to the late 1960s–early 1970s, when ecologists realized that this type of behavior could arise in simple mathematical models. A direct consequence is that such ecosystems can suddenly switch (or “tip”) between their alternative stable states rather than gradually responding to changes. In other terms, in these ecosystems, a small environmental perturbation can cause large, discontinuous, and irreversible changes, referred to as catastrophic shifts. This idea has attracted increasing interest in the literature over the years, and has become even more relevant in the current context of global change. Examples of catastrophic shifts in ecosystems include the eutrophication of shallow lakes, the desertification of drylands, and the degradation of coral reefs. Theoretical models have investigated the conditions under which alternative stable states and catastrophic shifts occur. A well-recognized cause of alternative stable states is the presence of strong positive—or self-reinforcing—feedback processes that maintain each of the stable ecosystem states. Understanding the mechanisms underlying the emergence of alternative stable states can help design management as well as restoration strategies for ecosystems. Because catastrophic shifts can have dramatic ecological and economic consequences, approaches have been proposed to detect possible alternative stable states in natural systems, and indicators of approaching ecosystem transitions have been identified (so-called early warning signals of critical slowing down).

General Overviews

The two books Scheffer 2009 and Petraitis 2013 provide introductions to the concepts, background theory, and empirical evidence of alternative stable states and catastrophic shifts in nature.

• Petraitis, P. 2013. Multiple stable states in natural ecosystems. Oxford: Oxford Univ. Press.

  DOI: 10.1093/acprof:osobl/9780199569342.001.0001

  This book presents the theory behind multiple stable states with an emphasis on testable predictions and links between theory and experiments. The book also contains extensive discussions on common misconceptions, misuse of the terminology, and caveats of both theoretical and experimental approaches focusing on alternative stable states in natural systems.

• Scheffer, M. 2009. Critical transitions in nature and society. Princeton Studies in Complexity. Princeton, NJ: Princeton Univ. Press.

  This book provides an accessible introduction to the basic theory of critical transitions and an overview of examples of critical transitions in a wide range of ecosystems as well as outside of ecology.