New satellite data shows that human actions are wiping out mangrove forests even faster than previous bleak estimates. Conducted by the US Geological Survey and NASA, the researchers found that mangroves comprise 12.3 percent less area than previously estimated. In total, satellites reveal that mangrove forests cover approximately 53,290 square miles (137,760 square kilometers).
"Our assessment shows, for the first time, the exact extent and distribution of mangrove forests of the world at 30 meters spatial resolution, the highest resolution ever," said Dr Chandra Giri from USGS.
Providing the best picture yet of mangrove placement, the study found Asia has most of the world's mangroves with 42 percent, followed by Africa with 21 percent, North and Central America with 15 percent, Oceania with 12 percent, and South America with 11 percent. However the study "reveals that 75 percent of the remaining
forest is found in just 15 countries, out of which only ~6.9 percent is protected under the existing protected areas network," says Giri.
Despite governments protecting so few mangrove forests, these tropical saline-adapted forests are one of the world's most important ecosystems. Mangroves serve as nurseries for a variety marine fish, underpinning global fisheries and providing additional food security in some developing nations. In addition, they store massive amounts of carbon and provide buffers against marine erosion. In all it has been estimated that mangroves provide at least $1.6 billion in ecosystem services annually.
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http://news.mongabay.com/2010/0819-hance_mangroves_satellite.html