Ecological Transitions: Regime Shifts, Thresholds and Tipping Points

by

Vasilis Dakos

• LAST REVIEWED: 29 November 2018
• LAST MODIFIED: 29 November 2018
• DOI: 10.1093/obo/9780199363445-0108

Introduction

Regime shifts, ecological thresholds, and tipping points are increasingly used in environmental sciences to describe abrupt ecological transitions ranging from population collapse to community reorganization, and even shifts at the whole ecosystem scale. Although all are intuitively understood, they sometimes remain contested and often loosely defined terms. Regime shifts describe persistent changes at population, community, or ecosystem level. Ecological thresholds are related to a strong nonlinear response in ecosystem state at a critical level of an environmental driver. Tipping points mark the onset of self-sustained responses that lead to strong changes in ecosystem state. All terms are related to the concepts of critical transitions, Catastrophe Theory, multiple stable states, and resilience. Ecological transitions are usually used with an alarmist notion even though they can refer to positive transitions (e.g., ecosystem restoration). They are often used in mixed ways: to represent a threshold in environmental conditions, to highlight the potential risk of abrupt shifts between Alternative States, or even as a metaphor for rapid anthropogenic changes at the level of the biosphere. There is a rich literature on understanding potential mechanisms behind the occurrence of ecological transitions and tools for their identification and timely detection. Most work is theoretical but with increasing empirical examples, as experimentation and long-term ecological data are becoming available. Due to their generic properties, regime shifts, thresholds, and tipping points are actively researched across scientific disciplines other than ecology for understanding the dynamics on systemic transitions in general.

General Overviews

Regime shifts are intricately related to the concept of Ecological Resilience (see the Oxford Bibliographies in Environmental Science article “Resilience” by Craig Allen, Ahjond S. Garmestani, and David Angeler), which was introduced in Holling 1973 to describe the possibility of shifting between alternative ecological states at the crossing of thresholds. Resilience and multiple states refer to properties of the stability of an ecological system (Grimm and Wissel 1997, cited under Historical Overviews) and were formally summarized in mathematical models of consumer-resource interactions (May 1977, cited under Definition, and Noy-Meir 1975, cited under Alternative States). The first observations of multiple states were described at the level of communities based on species differences in community composition before and after a disturbance (Sutherland 1974, cited under Alternative States). Later, the notion of multiple alternative states was expanded to describe shifts at the level of ecosystems, and gained a lot of focus in rangelands (Bestelmeyer 2006) and marine ecosystems (de Young, et al. 2008). In a comprehensive survey, Muradian 2001 lists five prominent ecological thresholds related to anthropogenic stress. Based on long-term data and experimental manipulations, the review by Scheffer, et al. 2001 argued for the importance and ubiquity of threshold behavior between (potential) alternative states in a variety of ecosystems. Scheffer’s review combined Holling 1973 ideas of ecological resilience with the mathematics of Catastrophe Theory in Thom 1976 (cited under Textbooks), and triggered a search for thresholds and the mechanisms of alternative states in ecology (Beisner, et al. 2003 cited under Alternative States). Thereafter, regime shifts between alternative states and resilience were suggested as novel ways to approach ecosystem management under global environmental change (Folke, et al. 2004), the idea being that natural systems are not responding always linearly to changing conditions but occasionally abruptly and irreversibly. A useful overview of multistability in different fields and between different dynamical behaviors can be found in Feudel 2008. Thresholds and regime shifts have been increasingly replaced in the ecological literature by the term “tipping point,” as explained in Lenton 2013 to describe threshold behavior in the Earth’s climate systems. Recent work suggests the existence of tipping points at the global biosphere (Barnosky, et al. 2012), and summarizes new approaches for Anticipating Ecological Transitions in advance (Scheffer, et al. 2012; Clements and Ozgul 2018).

• Barnosky, A. D., E. A. Hadly, J. Bascompte, et al. 2012. Approaching a state shift in Earth’s biosphere. Nature 486.7401: 52–58.

  DOI: 10.1038/nature11018

  This review suggests that global scale tipping points may be possible to occur at the scale of the biosphere.

• Bestelmeyer, B. T. 2006. Threshold concepts and their use in range management and restoration: The good, the bad, and the insidious. Restoration Ecology 14.3: 325–329.

  DOI: 10.1111/j.1526-100X.2006.00140.x

  A review of the application of thresholds in rangeland management with specific emphasis on irreversible (insidious) thresholds.

• Clements, C. F., and A. Ozgul. 2018. Indicators of transitions in biological systems. Ecology Letters 21.6: 905–919.

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  A review of different indicators used as early-warning signals for ecological transitions.

• de Young, B., M. Barange, G. Beaugrand, et al. 2008. Regime shifts in marine ecosystems: Detection, prediction and management. Trends in Ecology & Evolution 23.7: 402–409.

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  An overview of theory and issues in understanding and detecting regime shifts for marine ecosystems.

• Folke, C., S. Carpenter, B. Walker, et al. 2004. Regime shifts, resilience, and biodiversity in ecosystem management. Annual Review of Ecology and Systematics 35:557–581.

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  A highly cited work on the conceptualization of how biodiversity affects resilience and its link to regime shifts in ecosystems.

• Feudel, U. 2008. Complex dynamics in multistable systems. International Journal of Bifurcation and Chaos 18.6: 1607–1626.

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  A useful overview of multistability in different fields apart from ecology, including different dynamical types of attractors.

• Holling, C. S. 1973. Resilience and stability of ecological systems. Annual Review of Ecology and Systematics 4:1–23.

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  The prominent paper of Holling that triggered the development of the field of resilience, beyond the classical concept of local stability. This work was influential in studying thresholds, applying catastrophe theory to ecology, and even leading to a broader sense of system resilience in socioecological systems and from local to global scales.

• Lenton, T. M. 2013. Environmental tipping points. Annual Review of Environment and Resources 38:1–29.

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  This review is a complete treatment on the Definition, origin, mechanism, and detection of tipping points. It summarizes past Earth tipping points and highlights future ones, while it also discusses ideas on promoting favorable tipping points next to avoiding unfavorable ones.

• Muradian, R. 2001. Ecological thresholds: A survey. Ecological Economics 38.1: 7–24.

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  A nice review of thresholds in ecology with a historical overview from a perspective of an economist.

• Scheffer, M., S. R. Carpenter, T. M. Lenton, et al. 2012. Anticipating critical transitions. Science 338.6105: 344–348.

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  An overview of tools and studies on detecting tipping points in advance. It offers a list of modeling and empirical work on indicators of tipping points and highlights open questions in understanding tipping points in complex networks.

• Scheffer, M., S. Carpenter, J. A. Foley, C. Folke, and B. Walker. 2001. Catastrophic shifts in ecosystems. Nature 413.6856: 591–596.

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  A most influential review on catastrophic shifts in ecosystems with Alternative States. It re-emphasized the connection of catastrophe theory with regime shifts and the identification of multiple states and it is considered a classic read regarding ecosystem thresholds and tipping points.