Rating system for best habitats

10 April 2008

A groundbreaking new technique means conservationists can, for the first time, identify the habitats to conserve in the world's richest wildlife areas to protect the most species.

Using Madagascar as a case study, an international team including Natural History Museum scientists has revealed the most effective areas for expanding the island's existing network of nature reserves.

New software

The team used specially developed software to make detailed maps of how species are distributed down to the last kilometre.  Habitats were then rated by the number of species they support, prioritising species most vulnerable to habitat loss to calculate the best possible network of nature reserves using already protected areas.

Six major groups

Traditionally, conservation has focussed on protecting just one species or group, but in this project the team analysed more than 2,300 Madagascan species from six major groups: lemurs, butterflies, frogs, geckos, ants and plants.

The research showed that conserving habitats based on only one group of these organisms can exclude up to 50% of rare species from other groups. Overall, prioritising just one group of animals in any given area in Madagascar would exclude up to 39% of all species.

Complex web

'This is the first time we have been able to analyse so many species in such detail over an area this large,' said David Lees, butterfly researcher at the Natural History Museum and a co-author of the study.

'Our results have shown that basing conservation on the needs of single species groups like butterflies just isn't enough.'

'It is now feasible to map the complex web of life in the world's richest wildlife areas to help guide tough conservation choices, and increase chances of survival in the face of climate change.'

Overlooked habitats

The new report has surprised researchers by highlighting habitats overlooked in the past, such as coastal forests and central mountain ranges with small pockets of trees.

Madagascar's nature reserves have previously concentrated on scenic isolated blocks of forest, without an overview of how they are connected.

Biodiversity hotspots

Madagascar is renowned for its unique wildlife, from lemurs to brightly coloured chameleons. It is one of the world's biodiversity hotspots - for more than 80% of 30,000 known species, Madagascar is the only place in the world where they are found.

As in many biodiversity hotspots, pressures from economics and climate change are increasing the threat of habitat loss, making effective conservation planning essential.

Optimum network of reserves

David Lees commented, 'Conservation in biodiversity hotspots has to be about creating an optimum network of reserves that give the best compromise for the most species.'

'There is a trade-off between increasing extinction risk for individual species while protecting hundreds more that might otherwise be left out.'

'This study gives the Malagasy government a practical plan for conservation that complements its existing reserves and lies within its overall target.'

In 2003, the island's government committed to tripling its existing network of protected areas to 10% coverage including large forest corridors.

'Madagascar is one of the poorest countries in the world, which makes the government's commitment to biodiversity even more remarkable,' said Alison Cameron, co-lead researcher of the project, at University of California Berkeley.

'Government leaders have developed a very progressive vision for social and economic development, in which the natural landscape is viewed as a valuable resource.'

Scope of information

Previously, the scope and accessibility of information about species distribution has prevented scientists from evaluating habitats on species distribution, uniqueness and potential survival at the same time.

In addition, computing constraints made it difficult to make mathematical models accurate over large geographic areas.

The study is published in the journal Science today.