The coastal region of northern Brazil is home to one of the world’s largest mangrove forests. The area is a breeding ground for a larger variety of marine animals, with the mangroves protecting the coast from the waves and rising sea level. It was already known that these ecosystems store a significant amount of carbon dioxide, which is associated with climate change, and now their capacity for accumulating this greenhouse gas is becoming better known. A study by researchers in Brazil and the USA found that in the Amazon, every hectare of mangrove contains twice as much carbon as the same area of inland forest (Biology Letters, September 5). In the Northeast, one hectare of mangrove stores at least eight times more carbon than one hectare of the semiarid scrublands of the Caatinga. The team, coordinated by John Boone Kauffman, from Oregon State University, Angelo Bernardino, from the Federal University of Espírito Santo (UFES), and Tiago Ferreira, from the Luiz de Queiroz School of Agriculture at the University of São Paulo (ESALQ-USP), spent four years taking measurements from preserved mangroves and areas where mangroves have been deforested. In an earlier study, the same group calculated the amount of carbon dioxide these ecosystems release into the air when they are cut down—generally to make space for cattle pasture or shrimp farms. In Northeast Brazil, converting one hectare of mangrove into a shrimp farm emits about 10 times more carbon dioxide than burning one hectare of continental forest, based on the volume of carbon accumulated in the soil of a mangrove over 180 years (Ecology and Evolution, May).
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