Drought, fires affect the ability of Amazon to hold carbon dioxide

PhysOrg: Fires in the Amazon could jeopardize the forest's ability to soak up carbon dioxide emissions even as deforestation there slows down, according to a Penn State geographer.

In an invited commentary in the Feb. 6 edition of Nature, Jennifer Balch, assistant professor of geography, noted that dry weather conditions, coupled with fires, may mean that over time the Amazon forest will lose its ability to take in more carbon dioxide than it releases—going from being a carbon sink to a source.

"Aircraft have just recently captured the 'breath' of the entire Amazon forest," Balch said. "This is really important work that represents the first time that carbon fluxes from the Amazon basin have been obtained in this way."

Her commentary follows the work of researchers (whose findings are published in that edition of Nature) who used aircraft to profile how much carbon the forests are releasing. During drought conditions, the forests took up less of the carbon dioxide that comes with fires. That, coupled with a slowdown in photosynthesis, saw an upswing in carbon dioxide emissions from the forest dome.

An important next step, Balch wrote, is determining what types of fires—wildfires or those used for agriculture, for example—are behind the large amount of land that is burned every year. That information could help direct fire prevention and management in the future. Since the year 2000, 85,000 square kilometers of understory forests burned in the Amazon....

Viewed from space, fires and deforestation near Rondonia, Brazil. Image from NASA