Do early warning indicators consistently predict nonlinear change in long‐term ecological data?

Burthe, Sarah J.; Henrys, Peter A.; Mackay, Eleanor B.; Spears, Bryan M.; Campbell, R. N.; Carvalho, Laurence; Dudley, Bernard; Gunn, Iain; Johns, David G.; Maberly, Stephen C.; May, Linda; Newell, Mark A.; Wanless, Sarah; Winfield, Ian J.; Thackeray, Stephen J.; Daunt, Francis

doi:10.1111/1365-2664.12519

Cited by 115 publications

(120 citation statements)

References 74 publications

(135 reference statements)

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“…Our findings are in line with results from an assessment of the detectability of EWIs before nonlinear transitions (43). Although it is encouraging that we could detect EWIs in some of our empirical aquatic time series using data derived from commonly used monitoring schemes that were not designed for this purpose, the lack of reliability and agreement among signals limits the potential application of EWIs only to well-understood ecosystems (35).…”

Section: Resultssupporting

confidence: 85%

Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems

Gsell

Scharfenberger

Özkundakci

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

124

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Ecosystems can show sudden and persistent changes in state despite only incremental changes in drivers. Such critical transitions are difficult to predict, because the state of the system often shows little change before the transition. Early-warning indicators (EWIs) are hypothesized to signal the loss of system resilience and have been shown to precede critical transitions in theoretical models, paleo-climate time series, and in laboratory as well as whole lake experiments. The generalizability of EWIs for detecting critical transitions in empirical time series of natural aquatic ecosystems remains largely untested, however. Here we assessed four commonly used EWIs on long-term datasets of five freshwater ecosystems that have experienced sudden, persistent transitions and for which the relevant ecological mechanisms and drivers are well understood. These case studies were categorized by three mechanisms that can generate critical transitions between alternative states: competition, trophic cascade, and intraguild predation. Although EWIs could be detected in most of the case studies, agreement among the four indicators was low. In some cases, EWIs were detected considerably ahead of the transition. Nonetheless, our results show that at present, EWIs do not provide reliable and consistent signals of impending critical transitions despite using some of the best routinely monitored freshwater ecosystems. Our analysis strongly suggests that a priori knowledge of the underlying mechanisms driving ecosystem transitions is necessary to identify relevant state variables for successfully monitoring EWIs.

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Section: Resultssupporting

confidence: 85%

Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems

Gsell

Scharfenberger

Özkundakci

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

124

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“…Collectively, experiments that reveal clear evidence for resilience indicators have used explicit models of the ecosystem processes, detailed measurements tailored to the expected dynamics, and controls or reference ecosystems. In contrast, situations where dynamics are poorly understood, data are collected for another purpose, or reference ecosystems are not available may fail to generate discernible changes in resilience indicators (8). In addition, resilience indicators need to be evaluated under a wider variety of experimental conditions to better understand their efficacy.…”

Section: Discussionmentioning

confidence: 99%

“…The identification, drivers, mechanisms, and potential reversibility of regime shifts are debated and vary among ecosystems (6)(7)(8). Nonetheless, regime shifts in ecosystems warrant further research due to their massive consequences.…”

mentioning

confidence: 99%

Reversal of a cyanobacterial bloom in response to early warnings

Pace

Batt

Buelo

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Directional change in environmental drivers sometimes triggers regime shifts in ecosystems. Theory and experiments suggest that regime shifts can be detected in advance, and perhaps averted, by monitoring resilience indicators such as variance and autocorrelation of key ecosystem variables. However, it is uncertain whether management action prompted by a change in resilience indicators can prevent an impending regime shift. We caused a cyanobacterial bloom by gradually enriching an experimental lake while monitoring an unenriched reference lake and a continuously enriched reference lake. When resilience indicators exceeded preset boundaries, nutrient enrichment was stopped in the experimental lake. Concentrations of algal pigments, dissolved oxygen saturation, and pH rapidly declined following cessation of nutrient enrichment and became similar to the unenriched lake, whereas a large bloom occurred in the continuously enriched lake. This outcome suggests that resilience indicators may be useful in management to prevent unwanted regime shifts, at least in some situations. Nonetheless, a safer approach to ecosystem management would build and maintain the resilience of desirable ecosystem conditions, for example, by preventing excessive nutrient input to lakes and reservoirs.

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“…Zhang et al 2015). Ecological studies have reached similar conclusions, identifying a need to apply resilience metrics to multiple indicators and to consider resilience at species and ecosystem levels in order to derive more robust assessments (Angeler & Craig 2016, Burthe et al 2016). …”

Section: Defining Resiliencementioning

confidence: 93%

The application of resilience concepts in palaeoecology

et al. 2018

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The concept of resilience has become increasingly important in ecological and socioecological literature. With its focus on the temporal behaviour of ecosystems, palaeoecology has an important role to play in developing a scientific understanding of ecological resilience. We provide a critical review of the ways in which resilience is being addressed by palaeoecologists. We review ~180 papers, identifying the definitions or conceptualisations of 'resilience' that they use, and analysing the ways in which palaeoecology is contributing to our understanding of ecological resilience. We identify three key areas for further development. Firstly, the term 'resilience' is frequently defined too broadly to be meaningful without further qualification. In particular, palaeoecologists need to distinguish between 'press' vs. 'pulse' disturbances, and 'ecological' vs. 'engineering' resilience. Palaeoecologists are well placed to critically assess the extent to which these dichotomies apply in real (rather than theoretical) ecosystems, where climate and other environmental parameters are constantly changing. Secondly, defining a formal 'response model' -a statement of the anticipated relationships between proxies, disturbances and resilience properties -can help to clarify arguments, especially inferred causal links, since the difficulty of proving causation is a fundamental limitation of palaeoecology for understanding ecosystem drivers and responses. Thirdly, there is a need for critical analysis of the role of scale in ecosystem resilience. Different palaeoenvironmental proxies are differently able to address the various temporal and spatial scales of ecological change, and these limitations, as well as methodological constraints on inherently noisy proxy data, need to be explored and addressed.

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Do early warning indicators consistently predict nonlinear change in long‐term ecological data?

Cited by 115 publications

References 74 publications

Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems

Evaluating early-warning indicators of critical transitions in natural aquatic ecosystems

Reversal of a cyanobacterial bloom in response to early warnings

The application of resilience concepts in palaeoecology

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