‘Irreplaceable’ homes of endangered animals mapped – but did they get it right?

The grey-faced sengi, found only in remote East African forests, is related to elephants. Francesco Rovero

Kakadu National Park, Western Australia’s Shark Bay and Queensland’s wet tropics are among the world’s most important protected areas for conserving species, according to a study published today in the journal Science.

However, a number of scientists have questioned the study’s method and findings, warning it was based on flawed assumptions about how well World Heritage-listed sites protect animals, and that it risked making conservation efforts too slow and reactive.

Unlike previous studies that focused on increasing the number of protected sites, the new study tries to compare the value of each protected area for the long-term survival of species, to work out which areas of the world would make the biggest difference in slowing down the rate of species going extinct worldwide.

Michael Hoffman, a senior scientific officer at the International Union for Conservation of Nature’s Species Survival Commission and a co-author of the paper, said: “The novelty of this study is in ‘reversing’ the typical approach, and looking at how we could strategically expand the network of protected areas and improve the management of those sites.”

Wildlife at risk

The study looks at 137 protected areas in 34 countries, in which more than 600 species can be found. More than half of those are threatened with extinction, making the protected areas potentially crucial for their survival.

The authors of the study used existing datasets from the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species and the World Database of Protected Areas to calculate that there were 21,419 rare species of non-marine mammals, birds and amphibians inside 173,461 protected areas of land around the world, as well as 2,059 proposed sites.

They then ranked how unique those areas with an “irreplaceability” score, to indicate how important each area was in protecting all the species living in them, factoring in how easily you could find the same species in other places.

The study recommends that the areas they scored as most “irreplaceable” should be the highest priority for increased management.

Researcher at Centre d'Ecologie Fonctionnelle et Evolutive in France and coordinator of the study, Ana Rodrigues, said protected areas needed to be better cared for.

“Unfortunately, management is insufficient – sometimes even non-existent – in many protected areas. This study aims to guide priorities for protected area management.”

The endangered Red-ruffed lemur found in the rainforests of Madagascar. R.A. Mittermeier

Experts respond

University of Queensland landscape and conservation ecologist Martine Maron, who was not involved in the study, said the Science paper’s “irreplaceability” ranking could not help identify the most important conservation sites that are facing threats and need urgent action.

A number of other experts shared concerns about the way the new study determined how “irreplaceable” each protected area was, leaving some scientists unconvinced of its accuracy and usefulness.

According to Michael McCarthy, associate professor at the University of Melbourne, “irreplaceability” has been measured in several different ways in the past and there is no agreed standard.

“Without doing a thorough analysis, it is unclear whether the method used to measure ‘biodiversity value’ in this study is logical. It would be interesting to compare the new results against the old if previous methods for measuring ‘irreplaceability’ were used.”

The critically endangered harlequin frog used to be common in Colombia’s Sierra Nevada de Santa Marta Natural National Park until a fungal skin disease devastated amphibians worldwide. www.ProAves.org

PhD Candidate from the Australian National University, Megan Evans, agreed, saying: “Given that the authors did not test the level of agreement between other measures - like basic species richness, rarity and vegetation cover in protected areas - and the locations of current World Heritage Sites, it is unclear how their ‘irreplaceability’ score performed relative to these other, perhaps, more commonly used and more easily calculated measures. Without this information, we can’t tell whether the proposed ‘irreplaceability’ measure tells us anything new.”

Losing species in World Heritage areas

Several experts argued that a fundamental flaw in the study is its assumption that attaining a World Heritage site listing will be enough on its own to mean that the species in that area then get adequate protection.

“Here, it is assumed that ‘irreplaceability’ is important in the long-term functioning of the biosphere and that there is no change occurring in the systems. This goes against the authors’ proposal of introducing improved management strategies to the system,” said Peter Bridgewater, an Australian conservationist and visiting professor at the United Nations University.

As Ms Evans pointed out, Kakadu National Park is a clear example of how an area can win a World Heritage site listing and be well-managed - yet mammals in the park are still being lost at an alarming rate due to fire and feral cats.

Therefore, biodiversity “irreplaceability” should not be the only criteria used in identifying priority areas for management.

The Jim Jim River, in Australia’s Kakadu National Park, just before sunset. Flickr/WanderingtheWorld

A number of experts interviewed pointed to other factors that should also be considered before saying which particular areas were worth investing more time and money in, including:

  • The key threats facing species in an area, such as deforestation, invasive species and fire;
  • The management actions required to reduce these threats, such as controlling deforestation, invasive species and fire;
  • The costs of those actions;
  • The likely benefits.

Using that cost benefit approach was likely to result in a very different list of priority sites, rather than simply considering “biodiversity values”, such as “irreplaceability” and species richness, alone.

Gaps in the study

Associate professor at Murdoch University Susan Moore said while the study’s maps were an important starting point for developing conservation and management priorities, she questioned the Australian findings in it.

In particular, Professor Moore pointed to how the only “irreplaceable” protected areas in Australia overlapped completely with existing World Heritage sites, when it is highly likely that there are other species-rich parts of the country that haven’t won World Heritage listing yet.

For example, the southwest of Western Australia is a global biodiversity hotspot and critically important for the future of global biodiversity. But it does not appear on the map in this study.

“These findings present a very static view of the world at a time of increasing change. They reflect management for the present based on past criteria, focusing on sustainability rather than on resilience or refugia – arguably more important concepts during change,” said associate professor of environmental biology at Curtin University, Grant Wardell-Johnson.

“Will the sites harbouring the most biodiversity now be the same places that harbour the most biodiversity in the future? As climate and people move, will these protected areas still be of greatest importance for biodiversity?”

Professor Wardell-Johnson also cautioned that this study is focused only on a small fraction of the world’s species, and that a cursory scan of plants and biodiversity hotspots puts a very different spin on which are the most venerable and vulnerable places.

Just 2000 nilgiri tahr are found on the mountain cliffs and hills of the Western Ghats in India. Kalyan Varma

Conservation before it’s too late

“The next step will be to identify which of the prioritised protected areas are lacking adequate protection because, unfortunately, protected areas don’t always offer as much protection to species as you’d think,” said Anthony Waldron, a visiting professor at the Universidade Estadual de Santa Cruz in Brazil.

Freya Mathews, adjunct professor of environmental philosophy at La Trobe University, said while she understood why the study had focused on protecting of areas with threatened species, that approach risked making conservation efforts too reactive.

“If we prioritise species only when they become threatened, and areas only when they become the last strongholds of threatened species, then eventually, in the face of the relentless march of human population and development, all species and all areas will become threatened.

"It’s necessary to protect not only areas that are the last strongholds of threatened species, but also remaining areas of species richness and abundance, whether or not those areas are home to threatened species.”