June 9, 2013
NASA Satellites Calculate Damage Of Previously Undiscovered Amazon Wildfires
redOrbit Staff & Wire Reports — Your Universe Online
A previously undetected type of wildfire occurring in the Amazon region is responsible for far more rainforest loss than deforestation in recent years, NASA scientists have discovered using innovative new satellite techniques.
Known as “understory fires,” these wildfires have long remained undetected because they are located below the forest treetops, explained Tamarra Kemsley of Nature World News. However, researchers from the US space agency have for the first time been able to calculate regional estimates of understory fire damage throughout the southern part of the rainforest.
Writing in the journal Philosophical Transactions of the Royal Society B, NASA scientists describe how they used observations collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Terra satellite during the Amazon´s dry season, which lasts from June through August.
“They tracked the timing of fire damage and recovery, which varies depending on the type of forest disturbance,” the agency explained in a statement. For example, areas of deforestation were regions that lacked signs of recovery for at least two straight years, and signs of forest degradation resulting from understory fires tend to dissipate rapidly as the forest begins to regrow.
“The study shows that between 1999 and 2010, understory forest fires burned more than 33,000 square miles (85,500 square kilometers), or 2.8 percent of the forest,” they added. “Results also show no correlation between understory fires and deforestation. As the pressure for clearing led to the highest deforestation rates ever seen from 2003 to 2004, adjacent forests had some of the lowest rates of fires.”
Their research also demonstrated that in the years with the most understory fire activity, including 2005, 2007 and 2010, the areas of forest impacted were several times greater than those affected by the expansion of agriculture or deforestation, Kemsley said. Furthermore, NASA reported that fires in the savanna areas of the Amazon could spread up to 330 feet per minute, with shrubs and grasses often surviving these low-intensity surface fires.
“Amazon forests are quite vulnerable to fire, given the frequency of ignitions for deforestation and land management at the forest frontier, but we've never known the regional extent or frequency of these understory fires,” lead author Doug Morton of NASA's Goddard Space Flight Center said in a statement.
“You would think that deforestation activity would significantly increase the risk of fires in the adjacent forested area because deforestation fires are massive, towering infernos,” he added. “You make a bonfire that is a square kilometer in size, throwing ash and live cinders and preheating the adjacent forest. Why didn't we have more understory fires in 2003 and 2004, when deforestation rates were so high?”
Possible ignition sources for these fires include cooking, camping, cigarettes, motor vehicles, agricultural waste or other human catalysts, the researchers said. In addition, the discovery of the exact scope of these understory fires could alter the estimated carbon emissions originating from these disturbed forests. Morton reports that he and his colleagues are not yet sure what those emission levels are, but that “widespread damages suggest that they are important source of emissions that we need to consider.”