http://news.bbc.co.uk/1/hi/sci/tech/8095833.stmCutting down Amazon forest for cattle and soy does not bring long-term economic progress, researchers say.
A study of 286 Amazon municipalities found that deforestation brought quick benefits that were soon reversed.
Writing in the journal Science, the researchers say the deforestation cycle helps neither people nor nature.
They suggest that mechanisms to reward people in poorer countries for conserving rainforest could change this "lose-lose-lose" situation.
Jumbled paths
The Brazilian government has long had a twin-track approach to the Amazon, which contains about 40% of the world's remaining rainforest.
While the land development agency Incra settles people in the region as a way of giving them land and livelihoods - a policy that dates from the 1970s - the environment ministry is trying to reduce the rate of deforestation.
Last year the environment ministry named Incra as the country's worst illegal logger.
The Science study suggests that the settlement and expansion policy is not producing real benefits for people.
Ana Rodrigues and colleagues assessed the development status of people in 286 municipalities using the UN's Human Development Index (HDI), which combines measures of standard of living, literacy and life expectancy.
Some of the municipalities were in areas of virgin forest.
Others had already lost all their trees, and some were in the process of being deforested.
Areas in the initial stage of deforestation yielded HDI scores above the average for the region.
But once the period of deforestation had passed, scores returned to the values seen in areas that had not yet been logged.
"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," said Dr Rodrigues
"We found although the deforestation frontier does bring initial improvements in income, life expectancy, and literacy, such gains are not sustained."
The "boom and bust" pattern was the same for each of the three aspects of the HDI, showing that even a straight economic benefit was not maintained.
REDD dawn
As the study emerged, UN climate negotiators are meeting in Bonn to discuss aspects of a follow-on treaty to the Kyoto Protocol, which is suppposed to be finalised by the end of the year.
One of the aspects of the new treaty will be a mechanism that rewards local communities for keeping carbon-absorbing forests intact - a mechanism known as REDD (Reducing Emissions through Deforestation and forest Degradation).
Andrew Balmford, a co-author of the new study, said REDD and other proposals could change the current situation, which he described as disastrous for local people, wildlife and the global climate.
"Reversing this pattern will hinge on capturing the values of intact forests... so that local people's livelihoods are better when the forest is left standing than when it is cleared," said the Cambridge professor of conservation science.
"Discussions being held in the run-up to this December's crucial climate change meeting in Copenhagen... offer some promise that this lose-lose-lose situation could be tackled, to the benefit of everyone - local Brazilians included."
The research was possible only because Brazil has good data on human development and on deforestation, which these days is measured by satellites.
But Ana Rodrigues believes the conclusions probably hold true for other countries stocked with tropical forests in southeast Asia or west Africa.
"I would be very surprised if we didn't see this boom and bust pattern emerging in these areas as well," she told BBC News.
President Lula is currently debating whether to ratify a bill that would grant legal status to illegal settlers and loggers in the Amazon region.
Environmentalists say the bill would increase the rate of land-grabs, with a knock-on rise in illegal logging likely.
Richard.Black-INTERNET@bbc.co.uk
