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A New List to Frame Biodiversity Conservation

By David Salt

A new IUCN Red List promises to enlarge the debate on declining biodiversity to include ecosystems.

Declines in biodiversity have largely been debated through a species prism. Species are declining and disappearing. Unfortunately, no government on the planet is prepared to invest anywhere near the amount needed to save all the species in trouble because while people don’t like threatened species going extinct, they also expect our governments to provide hospitals, schools and police forces. At the end of day, conservation is but one of a range of activities supported by the government.

So, many species are in trouble and governments don’t invest enough resources to save them all. Choices have to be made. Which species do we allocate the limited resources to?

Current policy in most places around the world favours expenditure on the most threatened species. No politician wants a species going extinct on their watch. However, a growing number of researchers would like to see available resources achieving the greatest good, and this might not be achieved by only focusing on the most threatened species.

The thing is, the debate is all about species. The status of threatened species, therefore, is a cornerstone to biodiversity conservation. That’s in part because species are “units” that are relatively easy to distinguish and count.

It’s also in part because an international body, the Inter­national Union for the Conservation of Nature (IUCN), has developed a widely accepted list of threatened species that it updates each year. The IUCN Red List of Threatened Species assigns species to one of five risk categories – from “least concern” to “critically endangered” – with robust criteria for how any described species moves from one category to another.

But the status of species is but one facet of the conservation problem. Scientists have become increasingly concerned that the habitats of species and the ecological processes that influence the relationships between species are not adequately considered. What we have long needed is a Red List of Ecosystems, and this year the IUCN has delivered one. It’s a risk assessment framework for ecosystems that lets the IUCN rank ecosystems as endangered, vulnerable or not threatened according to the risks they face.

Defining, measuring and comparing ecosystems is a much tougher proposition than defining, measuring and comparing the status of threatened species (which is challenging enough in itself). It’s easy to observe that the Aral Sea is a collapsed ecosystem. The sea itself has largely disappeared and with it many of its native animals and plants – never to return. In terms of area, composition and function, this ecosystem is gone.

But what about the Coorong wetland or the Great Barrier Reef? They’re under tremendous pressure, but at what point should they be considered vulnerable as opposed to endangered?

Attempting to classify the threat level to ecosystems is a truly daunting task given the range of factors involved and things that could be measured. The Red List of Ecosystems assesses an ecosystem against multiple criteria: how rapidly is it declining and what is its current extent? How rapidly and how extensively is its physical and biological components degrading? And what is the nature of the multiple threats it faces and how are these threats interacting?

Scientists from around the world recently used the framework to assess 20 ecosystems to test how well it could be applied. They found that it enabled ecosystems to be compared. Of the ecosystems they compared, the remote mountain ecosystems of the Venezuelan Tepui are among those at least risk of collapse. These are showing little evidence of decline in distribution or function in the past or near future. At the other extreme is the Aral Sea, which collapsed during the 1980s and 1990s.

The Aral Sea assessment underscores the importance of healthy ecosystems. Not only were a host of species lost forever as the sea became hypersaline and dried up. This ecosystem collapse led to a socio-economic disaster that saw the closure of regional fisheries and major impacts on human health that continue to this day.

As an early warning system, the Red List of Ecosystems will help governments, industries and communities avoid ecosystem collapse and the associated socio-economic impacts by informing better environmental decisions.

While the state of biodiversity conservation around the world has up until now largely been framed by our perceptions of species loss, now we have a new and complementary prism to look through.

David Salt is a science writer with the Environmental Decisions Group. He is based at the Australian National University.