Rapid Changes and Thresholds

Detecting change and taking action

Three complementary decision points for biodiversity conservation

1. When thresholds are crossed
(it may be too late)

Freshly caught Atlantic cod © iStock.com/OKRADAction is delayed until the evidence of change is clear. For example, species decline below minimum viable numbers; too little habitat is left to support whole groups of species; extinctions. Options for action are limited and expensive. Interventions are drastic, with low likelihood of success. Recovery, if it occurs, is slow. Socio-economic impacts are inevitable.


Some examples from this assessment

Even with moratoria on fishing and reduced harvesting, action in response to declines in marine fisheries resulting from overfishing in the Atlantic and Pacific has not always been successful. The lack of recovery of some fish stocks is likely related to alteration of food webs and other aspects of ecosystems, making it difficult to return to past conditions. Earlier interventions might have improved prospects for recovery.

Since invasive non-native species and other changes took hold in the Great Lakes, large annual investments are needed to keep this altered system producing the ecosystem services that were provided naturally in the past.

2. When ecosystem changes are detected
(it is not too late)

Road through forest © iStock.com/wolv Earlier action, based on evidence that ecosystem change is underway, provides more options to mitigate impacts. Action is taken when cause-and-effect relations are at least partly understood and when evidence from research creates confidence that biodiversity declines are likely if no action is taken. Leads to a high probability of reversing or stabilizing impacts and reducing stressors before it is too late.

Some examples from this assessment

Fragmentation of landscapes is known to lead to the loss of habitat and species. It is difficult to measure the incremental changes in species themselves – but action to maintain large, intact landscapes will likely slow the rate of biodiversity loss.

Fire and insect disturbances have strong relationships with temperature and with forest practices. Severity and spread of certain forest insects and incidence of fire are likely to increase due to climate change. Policy options are available and have a good chance of success, including adapting fire and forestry management practices.

3. When early signals indicate there may be changeRed flag
(prevention possible)

Trees © iStock.com/chapin31Early signals of change are a source of information to use when developing policy options, managing proactively, and ensuring appropriate monitoring and research are in place. Early signals might be detected in a few locations only or in just some animals or plants in a population. These changes may turn out to be part of natural fluctuations – or they may be signs of bigger changes to come. Early action now may prevent problems in the future, be less expensive, and consequences may be less severe.

Some examples from this assessment

Invasive non-native species, including parasites, are often detected when they are just beginning to spread. Monitoring and early intervention have prevented the spread of some potentially harmful invasive non-native species, such as the gypsy moth in western Canada.

About 20 common species of birds are showing signs of widespread decline and the causes are unclear. Adapting research and monitoring to find out why is a first step in taking action to halt or reverse these declines.