Tropical rainforests are proving more resilient than environmentalists feared, with up to a third of the virgin jungle torn down by loggers and farmers sprouting new trees, scientists announced yesterday.

Aerial and satellite photographs presented at a scientific conference in Washinton show that trees have regrown in up to a third of tropical forests wiped out by loggers and slash-and-burn agriculture. The scientists found that while tropical forests are still being lost at a rate of 13,000 hectares each year – equivalent to 50 football pitches every day – the damage is less severe than some environmentalists have claimed.

The rainforest debate has raged publicly for decades, and more recently has been the subject of fierce argument among conservationists. These discussions are taking place as the international community tries to stem global warming and slow down the rate at which plant and animal species are becoming extinct.

The slow death of the rainforest was the main topic of yesterday’s conference at the Smithsonian National Museum of Natural History. Participants said that secondary forests were emerging in many parts of the tropics where small farms were being abandoned in deforested areas as urbanisation drew people away from rural areas. Deforestation is still the biggest trend in tropical regions, but it is now followed by land abandonment, especially in areas where farmers find it harder to make a living as people head to the cities, the scientists said.

The discovery that regeneration is taking place faster than was generally though has important implications for the rate of animal and plant extinction, because secondary forest areas provide a refuge for many animals and plants.

Researchers at the conference differed on how many tropical rainforest species can be expected to die out. Professor Eldredge Bermingham, of the Smithsonian Tropical Research Institute in Panama, said: “It’s a question of whether or not the biodiversity crisis has been overhyped.

“The increase in secondary forest that we are observing may provide a buffer against extinction. Therefore, the extinction crisis isn’t as serious as had been touted.”

Professor William Laurance, also from the institute, believed that 25 to 50 per cent of species will be lost. In contrast, other researchers put the likely level of species losses in the range of 15 to 30 per cent, perhaps even lower.

Both forecasts were high but were well below the “apocalyptic forecasts” of 50 to 75 per cent that had become widely accepted, they said.

Professor Laurance estimated that a quarter to a third of deforested areas had grown back as secondary forest – where species types are less varied and where plants have had only a few years, perhaps a few decades, to establish themselves.

He said: “We are still having a devastating loss of forests. It’s just that there’s some suggestion now that it is partly offset by the regeneration of secondary forest.”

The loss of forests worldwide contributes about a fifth of the world’s emissions of carbon dioxide into the atmosphere where it drives global warming.

Since the start of the Industrial Revolution, half of the 7.8 million square miles (20 million sq km) of virgin tropical forest has been destroyed. A further 1.9 million square miles has been “selectively logged” with favoured trees being cut down and large clearings created.

More than 500 scientists, politicians, and representatives from think-tanks and nongovermental organisations attended the conference held to inform them about the extent and dangers of deforestation.

Cristián Samper, director of the Smithsonian National Museum of Natural History, said: “By bringing together the world’s foremost authorities on different aspects of rainforest science, we hope to achieve new insights into a situation with potentially profound implications for all species – ours included.”

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