Chopping down the Amazon rainforest to make way for crops or cattle has no economic or social benefit for local people in the long term, according to a major new study.
The finding undercuts the argument that deforestation, which causes 20% of the globe's greenhouse gas emissions, leads to long-term development.
Conservationists showed communities develop rapidly but temporarily when forests are cleared. But rates of development quickly fall back below national average levels when the loggers move on and local resources near depletion.
More than 155,000 square kilometres of Amazonian rainforest in Brazil have been cleared for timber or burned to make way for agricultural land since 2000. Every year, around 1.8m hectares are destroyed — a rate of four football fields every minute. The Amazonian rainforest is one of the most biodiverse regions in the world, guarding against climate change by absorbing CO2 and maintaining geochemical cycles.
But some argue that local communities, which are among the poorest in Brazil, should be able to benefit from the local resources by creating farms or logging the trees. To calculate these potential benefits of deforestation for local communities, a team of international scientists analysed the life expectancy, literacy and income of people living in 286 areas around the Brazilian Amazon.
Their results, published today in Science, showed that the quality of life for local communities improved rapidly when a forest first cleared. "The monthly average income started out at 74 Reals per month," said Rob Ewers of the department of life sciences at Imperial College London, a member of the study team. "Then it went up to as much as 196 Reals per month in the middle [of the deforested area] and then to 82 once the resource is gone. Literacy went from 68% at the frontier [of the forest] up to a maximum of 83% then dropped down to 69%."
The researchers said that the cycle occurred because, at first, the newly available natural resources in an area of cleared forest attract investment and infrastructure. New roads can lead to improved access to education, medicine and an increased overall income gives people better living conditions.
But once the timber and other resources dry up, things change. "A lot of the agricultural land is only productive for a few years so once you lose that, you also lose that as a source of income," said Ewers. "On top of that you tend to have much higher populations because a lot of people have been attracted to the area."
This higher population has to survive on ever-dwindling local resources, pushing the standard of living right down again.
Ana Rodrigues of the Centre of Functional and Evolutionary Ecology in France, and lead author of the study, said: "The Amazon is globally recognised for its unparalleled natural value, but it is also a very poor region. It is generally assumed that replacing the forest with crops and pastureland is the best approach for fulfilling the region's legitimate aspirations to development. This study tested that assumption. We found although the deforestation frontier does bring initial improvements in income, life expectancy, and literacy, such gains are not sustained."
Greenpeace forests campaigner Sarah Shoraka said the research undermined any arguments that deforestation tackles poverty. "Slashing and burning rainforest to make way for cattle ranches or soya farms is simply not sustainable, because profits are short lived and the big companies simply move elsewhere. Instead we need sustained international funding to protect this massive natural resource, to make trees worth more alive than dead."
Andrew Balmford of the University of Cambridge said that the "current boom-and-bust trajectory of Amazonian development is therefore undesirable in human terms as well as potentially disastrous for other species, and for the world's climate. Reversing this pattern will hinge on capturing the value of intact forests to people outside the Amazon so that local people's livelihoods are better when the forest is left standing than when it is cleared."
This could be achieved in part, he said, by international schemes where rich countries could pay Brazilians to maintain their forests, which would lock up the carbon contained within them in a bid to tackle climate change but also provide locals with an income.