Editorial: “Rebuilding not rewinding is the future of conservation“
See more in our gallery: “Six threatened and not-so-threatened ecosystems“
WE MAY be living through the sixth great extinction. Rather than trying to preserve individual species, should we be focusing more of our efforts on saving entire ecosystems?
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This is the thinking behind a new way of assessing the global health of nature – the Red List of Ecosystems. It has been developed by the International Union for Conservation of Nature (IUCN), and is based on its Red List of Threatened Species, which assesses threats to species from Paraná pine trees to pandas. But rather than attempting to conserve all ecosystems, like the original does for species, controversially the new list may highlight which ecosystems are beyond help.
Its launch, which will officially take place later this year, coincides with a change in emphasis for conservationists: rather than trying to restore the planet to the halcyon days of old, many believe we must accept that Earth is being irreversibly transformed, and simply try to make the best of what we have. This means considering once unthinkable strategies, such as introducing non-native species and leaving some ecosystems to their fate.
The new Red List is a step beyond anything currently being done in national parks and marine protected areas: it will be a standardised assessment of all the world’s ecosystems, including ones transformed by humans, and should allow direct comparisons between them. This information will then be used to galvanise governments, help conservationists weigh up where to focus their attention, and where possible or worthwhile, provide suggestions of how to rehabilitate the land.
Last week, IUCN researchers published details of their assessment methods, and used this to gauge the health of 20 sample ecosystems (see “Collapsed: Aral Sea, central Asia“, “Endangered: Giant kelp forests, Alaska“, “Least concern: Tepui mountains, Venezuela“). Ecosystems are considered threatened if they are small or shrinking, if life-support systems like soil are being lost, or if crucial processes such as predator-prey relationships are being disrupted. Combining these measures gives an estimate of how likely the ecosystem is to collapse within the next 50 years and will provide the tools needed to make the tough decisions ().
With this in place, the survey will now begin in earnest. “Over this year and next, we will do the American continents,” says of the Center for Ecology in Caracas, Venezuela. The aim is to assess all the world’s ecosystems by 2025.
Ecologists are welcoming the new list. of the Zoological Society of London says it will focus the public’s attention on the services that ecosystems provide, like clean water and pollination of crops.
But it also raises hard questions about how best to take care of biodiversity. “Countries may decide they only want to focus on things that are not at risk,” says Rodríguez, because intact ecosystems are cheap to protect, whereas restoring damaged ones is difficult and expensive.
Restoration is possible, even in difficult environments, says of the Nature Conservancy in Newmarket, UK. With Caribbean reefs declining, the in Key Largo, Florida, has built coral nurseries to act as a safe haven for corals, . The reefs are then rebuilt using the nursery’s corals.
But such intensive projects cannot work everywhere. A recent study estimates that meeting our global biodiversity targets would cost the world’s governments $76 billion every year, and that’s just for land species (). “We’ve got to pick our fights,” says of the University of York, UK, and decide which aspects of ecosystems we really care about. “Not all change is negative,” he says. As well as choosing which ecosystems are beyond help, there could be places where there is no need to intervene.
“We’ve got to pick our fights and decide which aspects of ecosystems we really care about”
A study published this week, for example, describes the results of erecting a greenhouse on the Alaskan tundra – an important carbon sink – to examine how it would change as the climate warms. Over 20 years, the enclosed landscape changed dramatically: a woody shrub spread rapidly while lichens and mosses shrank back. But the amount of carbon in the soil stayed the same (). For Thomas, it doesn’t necessarily matter that the original habitat was replaced by a new one, because its function remained the same.
We also need to rethink our attitudes towards introduced species, says of the University of Zurich in Switzerland. Conservationists generally try to stop species getting into new areas, because they can become harmfully invasive, but Hansen says introduced species can be a boon.
When a species goes extinct, its ecosystem often loses a crucial function, but adding another species can fix this. On Mauritius, for example, giant tortoises once acted as seed dispersers for plants. When the tortoises were wiped out, the native plants suffered, so in 2000, conservationists started : Aldabra giant tortoises, an endangered species from a nearby island. “It has worked,” says Hansen. Similar tortoise projects are now being tried on and .
Another introduction may have helped to restore Puerto Rico’s forests. A century ago the island was deforested to grow sugar cane, which was later abandoned. The space was quickly filled by the accidental spread of imported . That sounds bad, but the tulip trees helped to regenerate the soil, allowing the to follow in their wake.
These ideas are still dividing conservationists. Jones says introducing species has had devastating consequences in the past, for example, when rabbits taken to Australia became a plague. Hansen is more optimistic. He says islands are ideal testing grounds to look for unintended outcomes before scaling up. But to really make a difference, “you need to do it at the continental scale”.
And if assessed according to a Red List that measures ecosystem health in the round, these daring strategies may one day be judged a success.
Collapsed: Aral sea, central Asia
The Aral Sea (see main picture) was once one of the world’s largest lakes, home to a host of unique species including the Aral Sea trout. But not any more.
In the middle of the 20th century, Soviet engineers dammed the rivers flowing into it and the Aral Sea almost vanished, replaced by a wasteland of salt, dust and abandoned fishing boats. The area’s fishing industry collapsed, leaving people with no livelihood, and the windblown dust took a toll on people’s health.
Some small lakes remain, but little lives in them besides algae. One of the lakes is now growing again, thanks to a World Bank project that has spent millions of dollars on funnelling water into it. “In theory collapse is reversible,” says Jon Paul Rodríguez of the Center for Ecology in Caracas, Venezuela, but many of the native species have been lost.
Endangered: Giant kelp forests, Alaska
The oceans off Alaska were once dominated by vast forests of kelp, a type of seaweed. But overfishing has indirectly devastated them.
A shortage of fish forced killer whales to eat sea otters. The numbers of sea urchins, which the sea otters eat, exploded, and in turn, the kelp the urchins feed on was gobbled up.
In many places, kelp forests have been replaced by open water. Reintroducing otters could restore the forests, but only if the killer whales can find enough food that isn’t otters.
Least concern: Tepui mountains, Venezuela
The tepui are vast table mountains made of granite and sandstone in the south of Venezuela. They are home to unique collections of strange plants and animals that are cut off from the lowlands below by the sheer cliffs.
The IUCN says they are at low risk, simply because they are so remote; most Venezuelans live far away in the north of the country.
In the long run, climate change may threaten them. Higher temperatures will force species uphill – until they reach the flat tops and have nowhere else to go. But for the next 50 years, the tabletops should be safe.
This article appeared in print under the headline “Forget the fish. Save the seas!”
