Science: Clear-Cutting Declines in Brazil’s Rainforest, but Fires Are on the Rise

Evidence of fire leakage from a deforested land into the surrounding forest in Mato Grosso state, southeast Amazonia.

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[Image courtesy of Instituto Centro de Vida]

Although the Brazilian Amazon has recently experienced a decline in deforestation rates, researchers writing in Science say that forest fires in the region are on the rise—and that the benefits of decreased deforestation could be partially offset by increased carbon dioxide emissions from those fires.

The growing incidence of forest fires appears to be primarily linked to human agricultural activities near re-forested areas or forest edges. As a result, the researchers report, a global program of financial incentives designed to “reduce carbon emissions from tropical deforestation and forest degradation” could fall short of its goals unless people living in the Brazilian Amazon adopt an organized fire control policy.

To investigate the likely behavior of fires in the context of reduced carbon emissions in the Amazon, Luiz Aragão from the University of Exeter in Devon, England, and Yosio Shimabukuro from the National Institute for Space Research (INPE) in São Paulo, Brazil, used satellite imaging to monitor the Brazilian Amazon rainforest from 1998 to 2007. Their study was published in the 4 June 2010 issue of the journal Science.

“The work was motivated by the fact that several global circulation models show that the Amazon will get drier in the 21st century, making it a fire-prone system,” said Aragão. “We wanted to understand how fires might affect the implementation of policies that create incentives for reducing carbon emissions from deforestation and forest degradation in the Amazon.”

Such forest-preservation incentives for developing countries were drawn up over recent years at the United Nations Framework Convention on Climate Change. They eventually came to be known as Reducing Emissions from Deforestation and forest Degradation, or REDD.

In order to understand the impact wildfires might have on REDD implementation in the future, the researchers investigated three hypotheses.

The first proposed that fire incidence would decrease with the implementation of REDD policies, because there would be fewer ignition sources from farming and other human activities. Another hypothesis put forth that fires would increase, even with decreased deforestation rates, due to the deforestation of secondary forests and the enlargement of forest edges, which are more susceptible to fires. Finally, a third hypothesis proposed that fire would decrease along with the implementation of REDD due simply to shifts in land-use and land management.

Aragão and Shimabukuro analyzed fire data from a U.S. National Oceanic and Atmospheric Administration satellite as well as deforestation data from INPE, and found the second hypothesis to be the strongest: The very same regions of the Amazon that have been spared from deforestation in recent years have experienced an up-tick in fire occurrences in the meantime.

In light of their observations, the researchers suggest that REDD might be successful at curtailing the clearing of large original forest areas—but that fires and their associated carbon emissions still threaten the long-term success of REDD.

Aragão and Shimabukuro are now calling for a more robust monitoring system that can monitor secondary forests (which are not currently monitored) along with the Brazilian Amazon. They also suggest that the introduction of managed agriculture, in place of the traditional slash-and-burn techniques, might help to decrease the number of fires in the Amazon and allow REDD to meet its goals of reduced carbon dioxide emissions worldwide.

Brandon Bryn

7 June 2010