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Defining 'ecosystem collapse'

Scientists develop a new standardised process for defining ecosystem collapse

In recent years the natural world has undergone rapid change. Conservation scientists measure the risks to species and ecosystems using Red Lists, such as the International Union for the Conservation of Nature's (IUCN) Red List of Ecosystems (RLE). The RLE is the global standard instrument to measure the different risks ecosystems are subject to, and estimates the risk based on change in environmental indicators through time or across space.

  

A key step in measuring risk is defining a clear negative outcome, or end point, which for an ecosystem is ecosystem collapse. An ecosystem moves into a collapsed state once it has lost its defining environmental or natural features, or has been replaced by a different type of ecosystem. Yet defining the point at which an ecosystem moves into a collapsed state (i.e. collapse threshold) can be a challenge.

A team of scientists has recently created a four-step guide which describes how to define ecosystem collapse and thus to help to improve consistency among risk assessments. They reviewed studies of marine pelagic ecosystems and temperate forests in order to work out how an ecosystem collapse is often described. They found that most studies defined collapsed ecosystem states quantitatively, but often lacked clear descriptions of the ecosystem processes leading to collapse.

The team concluded that scientists and managers applying the RLE assessments, or other risk assessment tools, should firstly quantitatively define all initial and collapse ecosystem states, and describe the ways that an ecosystem can move away and recover from collapse. Once they have a clear understanding of the dynamics of the ecosystem, they should identify and select a range of useful and sensitive indicators representing various parts of the ecosystem. Using a range of indicators improves the chances of detecting harmful change. And finally, quantitative collapse thresholds that separate intact states from collapsed states must be set for each indicator.

This new process is a major step towards ensuring risk assessments are reliable, transparent and open to be compared.  Consistency among risk assessments is precisely the element that allows the relative risk among ecosystems to be compared. This supports scientists, managers and policy-makers in making timely and suitable decisions to ensure effective action.

The paper “Developing a standardised definition of ecosystem collapse for risk assessment” was published in January 2018 in Frontiers in Ecology and Evolution.

 

Written by Jessica Rowland

Style and Format: Ana María Fernández

 

Provita Feb 10, 2018

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