Published online 26 October 2010 | Nature | doi:10.1038/news.2010.563

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Conservation offers hope for biodiversity decline

Though almost 20% of vertebrate species are in danger of extinction, conservation efforts are having an impact, a study calculates.

Black-footed ferretThe black-footed ferret has bucked the biodiversity trend thanks to conservation efforts - though it remains endangered.Wendy Shattil & Bob Rozinski

A fifth of vertebrate species are at risk of extinction, but biodiversity decline would have been considerably worse without conservation efforts, an analysis published today suggests.

The study, published in Science1, which summarizes the status of more than 25,000 mammals, birds and amphibians, was released to coincide with the UN Convention on Biological Diversity meeting in Nagoya, Japan, where delegates this week are expected to set targets to halt loss of the world's biodiversity by 2020 (see 'Biodiversity hope faces extinction').

"We've failed in meeting the 2010 targets [to cut species loss 'significantly' by this year]," says Michael Hoffmann of the International Union for the Conservation of Nature (IUCN) in Cambridge, UK, who led the vertebrate study, "but the aim of our paper is to demonstrate that actually conservation is making a difference".

A second study published in the same issue2, points out that computer models currently used to estimate future biodiversity loss are unreliable and inconsistent, which will hamper attempts to predict how policy decisions made in Nagoya will affect the world's flora and fauna.

"We have to work on narrowing down the likely dimensions of the crisis," says Henrique Pereira at the University of Lisbon in Portugal, who led this work. "At the moment we don't know whether we will lose 1% of biodiversity or between 40% and 50% by 2050."

Worse? How could it be worse?

Using an index of extinction risk based on category movements in the IUCN Red Lists of threatened mammals, reptiles, birds, amphibians and fishes — including some listings dating back as far as 1980 — Hoffmann's team showed that, on average, 52 vertebrate species have moved one Red List category closer to extinction every year.

Amphibians are the most likely to be sliding towards extinction: 42% are classified as 'threatened', mainly due to the poorly understood infectious disease chytridiomycosis, which has decimated populations around the world. Increases in extinction risk are most marked in Southeast Asia, although wealthier countries such as the United States and Australia have also suffered declines.

Rhys Green, professor of conservation science at the University of Oxford, says the paper is important because it pulls together disparate assessments — "including the less 'cuddly' groups".

But the study also estimates that biodiversity declines would have been at least one-fifth as much again if there had been no effort to halt habitat loss, curb hunting and tackle invasive species. "People don't believe that we can really do anything about the situation," says Hoffmann, "but if it hadn't been for the conservation effort, the declines we've seen would have been much worse."

Golden Lion TamarinThe golden lion tamarin, still endangered, has benefited from three decades of conservation work to strengthen population numbers.Frans Lanting/FLPA

And the true impact of conservation may be even more positive. The figures are a "woeful underestimate", says Hoffmann — partly because it is hard to spot species that would have slipped IUCN categories but haven't because of conservation efforts. Tackling invasive species seems to have produced the best results so far, but probably only because this strategy is particularly effective at lessening threats on isolated islands, Hoffmann says.

In some cases, conservation efforts have brought species back from the brink, such as those that repopulated parts of North America with the still-endangered black-footed ferret (Mustela nigripes) and a three-decade programme that saw the golden lion tamarin (Leontopithecus rosalia) downlisted to "endangered" from "critically endangered" in 2003.

Unknown unknowns

Meanwhile, the review of computer modelling of biodiversity, led by Pereira, says that inconsistent assumptions and an absence of hard data on the ground are the main barriers to predicting how biodiversity will change in the future.

Some studies extrapolate trends from previous correlations of changes in land use or climate with biodiversity loss. Others include details of the processes by which a species will become extinct as their surroundings change. All suggest we are facing a biodiversity crisis, but because they use different scenarios for climate and land-use change, estimates of the extent of future loss and of our ability to mitigate it diverge widely between the models.

"I think the biggest challenge for the community is to develop a better observation network for biodiversity change," says Pereira. And, he adds, "We need a bigger effort from the community in terms of comparing projections for the same set of scenarios. Then we could ascertain whether variations in outcomes were caused by the different models or by the different scenarios analysed."

"This review definitely needed to be written," says Green of Pereira's paper. "It paints a somewhat depressing picture, as there's still a lot of uncertainty."

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Both Pereira and Green hope that the establishment of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services — a biodiversity-based equivalent of the Intergovernmental Panel on Climate Change — will rally the biodiversity research community to work together on improving models and making sure that outcomes are comparable, and to establish better monitoring systems (See: 'UN body will assess ecosystems and biodiversity'). 

Although the Nagoya negotiations are currently stalling on detailed aspects of conservation funding and access to the resources of ecologically rich nations, Hoffmann remains optimistic. As he concludes from his review of conservation efforts: "We can really turn things around and that's a powerful message — you should never give up hope." 

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  • #60873

    A gene could be considered as more than just the protein-coding sequence, and include the regulatory sequences. I think promotors, enhancers, binding sites are all present in the DNA sequence, but don't get decoded into a protein, although they do exert their influence on the entire process.

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