Intentional deforestation in rainforests has gained much attention, but in a report in the Feb. 27 edition of the British science journal Nature, a Michigan State University researcher discovers that beneath the heavy smoke of intentional burns lie unintentional out-of-control fires that are devouring millions of acres of forests.
“These rainforest fires are much more frequent than these ecosystems can resist,” said the paper’s author, Mark Cochrane, a research scientist at Michigan State’s Center for Global Change and Earth Observations. “These fires are flying under the radar and people don’t realize what’s happening. If frequent burning of these forests continues, we’ll end up with a very different ecosystem.”
Cochrane studied satellite images and explored tropical rainforests and surrounding areas of human encroachment in Latin America. Other research has shown that fires pose similar threats in Southeast Asia and Africa. His results underscore a crucial need to better understand how fire behaves in rainforests and how unintended fires can be detected and contained.
Fire in a rainforest behaves differently than fire in temperate forests, such as in North America. Rather than rage, rainforest fires initially often creep slow and low along the bottom of the dense tropical growth. Cochrane said what they lack in drama, they make up for in ferocity. The bark of most tropical trees is thin. A small ground fire snaking through the rainforest can mortally wound 40 percent of the trees.
Often, it’s a slow death. Small trees go first. Older trees eventually fall. The forest is thinned and weakened, leaving it susceptible to more fires, which have a greater chance of gaining strength to a full-fledged inferno.
“The frustrating thing is, that these small fires are so easy to deal with the first time around,” Cochrane said. “You practically can stomp them out, or just sweep away brush ahead of them with a broom. But subsequent fires are of huge intensity that are extremely difficult to put out.”
From there, the troubles expand. Forests are decimated. Smoke endangers populations. And rare plant species, from the rainforest’s rich biodiversity, can be eradicated.
Carbon emissions skyrocket. Data is scarce, but Cochrane notes that three rainforest fires in Mexico, Brazil and Indonesia may have equaled 41 percent of world fossil fuel emissions in 1998.
The problem, Cochrane said, is that fire is so common in rainforests. People routinely use fire to clear existing forests, to keep cleared land free from brush, to cook and other uses. Satellite images of rainforest regions show vast areas of smoke and fire but it’s nearly impossible to tell which fires are intentional.
Cochrane’s research shows broad forest fragmentation above and beyond the intentional clearing of rainforest. The specialized satellite images he has created show a different type of destruction. The areas damaged by unintentional fires aren’t shown by cleared squares, but rather thinned, decimated clumps where rich forest once grew.
More research is needed to better understand fire behavior and how to fight forest fires in rainforests, Cochrane said.
“We need to recognize this as a problem that needs energy and action, before it gets worse,” he said. “What isn’t clear is how long it takes after the forest burns for it to recover. But it’s a safe bet that some of them never will.”
The research was funded by NASA.
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