Verdict on world's most precious nature reserves: overpopulated, overfarmed and under threat

They are the jewels in the crown of world wildlife. Rich in animals and plants, they are festooned with biological curiosities that play a leading role in the story of evolutionary diversity. They are also overpopulated, overfarmed and under threat.

They are the jewels in the crown of world wildlife. Rich in animals and plants, they are festooned with biological curiosities that play a leading role in the story of evolutionary diversity. They are also overpopulated, overfarmed and under threat.

A two-year investigation into the world's 17,000 main nature reserves ­ specifically established to protect wildlife ­ has discovered that almost half are now being farmed for food. Human hunger has become the enemy of wildlife preservation. In 16 of the world's 25 species-rich regions, scientists have identified severe malnutrition among the people.

As things stand, 24 per cent of mammals, more than 12 per cent of birds and nearly 14 per cent of plants are facing extinction. Wildlife is now more threatened than at any time since the last mass extinction, when the dinosaurs died out 65 million years ago.

With the apparent breakdown of protection for wilderness areas, scientists are calling for a radical switch in emphasis. They want farming and conservation to be united under the single banner of "ecoagriculture". Rather than rely on fences and prohibitions to curb farming of protected land, the new philosophy aims to boost agricultural production by using scientific advances from genetics to satellites.

The aim is simple: if farmers can double or even treble food production on land they already use, they will have less need to encroach on pristine areas. That is a drastic break with traditional conservation policies and common agriculture techniques, according to a report by the World Conservation Union (IUCN).

The report ­ Common Ground, Common Future ­ draws on advice from 10,000 scientists in 181 countries, and from a think-tank based in Washington, Future Harvest. It catalogues the failure of existing attempts at wildlife preservation. If present trends continue, a quarter of the world's wild plants and animals, and a half of those living in forests, could be extinct or seriously endangered within 50 years.

"More than 1.1bn people now live within the world's 25 biodiversity 'hotspots', areas described by ecologists as the most threatened species-rich regions on Earth," the IUCN says. "Population in tropical wilderness areas is, on average, growing at a rate of 3.1 per cent ­ over twice the world's average rate of growth."

To grow more food, most farmers try to eliminate wild species, to rid their land of pests and predators. Conservation tries to prevent this, but the protection covering just under 10 per cent of the Earth's land surface is not sufficient to protect wild biodiversity, says the report. Projections based on accepted ecological principles suggest that, if there is no increase in wildlife habitat, between 30 and 50 per cent of species will still be lost.

Regions of the greatest biological diversity are under greatest threat. Nearly 60 per cent of the world's poorest people live in the warm tropics, putting intolerable pressure on neighbouring rainforests ­ home to about half of the world's total number of animals and plants.

"To be a 'good' farmer [pre-conservation] meant clearing the wild," the report says. "Later, clearing of natural vegetation and creating uniform fields was further encouraged by mechanisation." Now the trade-off between food production and wildlife protection seems more difficult. "If they want to protect a little more biodiversity, they must sacrifice a lot of production; if they want a little more production, they must sacrifice a lot of biodiversity." The real challenge is to protect wild species and conserve habitat while increasing agricultural production and farmer incomes.

Jeffrey McNeely, one of the report's co-authors, said it was clear that traditional approaches to nature conservation had failed to take into account the unrelenting increase in the demand for food.

"Many people believe that biodiversity can be preserved simply by fencing it off. Our report shows that agriculture and biodiversity are inextricably linked," said Dr McNeely, the IUCN's chief scientist.

"To avert widespread extinctions and feed the world, we must integrate biodiversity preservation into all landscapes, from grazing lands to coffee plantations to rice paddies," he said.

The Singapore Botanic Garden, founded in 1859, is a supreme example of the failure of the nature reserve principle. This small, protected fragment of lowland tropical rainforest has lost half of its 448 recorded plants over the past 100 years.

About 50 per cent of the tree species growing there are represented by only one or two living representatives, a known indicator of imminent extinction. Other animals under "protection", such as the Javan rhinoceros and golden Vizcacha rat, are also dying out.

"Protected areas are fast becoming islands of dying biodiversity because of the agricultural areas that surround them," Dr McNeely explained.

"Many animals need the ability to migrate in order to avoid extinction. Limited reserve areas cannot fill this need and the lands that would be needed for massive expansion of protected areas is already being used to feed local people and fuel local economies.

"Ecoagriculture offers a solution to this dilemma by allowing farmers to produce more food on the same amount of land while greatly reducing harm to wildlife," he said.

The report details six way of implementing ecoagricultural techniques, from increasing yield using chemical fertilisers and crop breeding, to improved livestock management and enhancing wildlife habitats within agricultural land.

Scientists, for instance, have helped to improve crop yields among Honduran farmers with new varieties of coffee and vegetables. As a result, the farmers abandoned less-productive marginal land,which has since reverted to natural forest.

In contrast, Honduran communities that continued to use their traditional methods saw forest cover decline by more than 13 per cent, and up to 20 per cent in some cases, Dr McNeely said.

In Costa Rica, farmers are experimenting with interspersing trees in pastures to shade their cattle and provide a near-natural habitat for some species of local flora and fauna.

In China, planting more than one variety of rice has increased resistance to disease and improved yields, although a burgeoning population is still encroaching on nature reserves.

"Many of the new approaches to ecoagriculture will require a change in the mindset for many farmers," said Professor Sara Scherr of the University of Maryland in Washington DC, another of the report's authors.

"For centuries, farmers have generally done their best to clear land of natural vegetation and keep wildlife off their farms. This was a sign of a good farmer. Now we're asking farmers to let some of the wild back in," she said.

"We are not suggesting that elephants could be allowed to trample farmers' fields. We are saying that there are strategic solutions for conserving wild biodiversity and producing food on the same land."