New tracking method

Satellites track S America deforestation London - Arabstoday   An international team of researchers says it's developed the first system to monitor deforestation across Latin America in near real time using satellite data. Scientists from Colombia, Britain, the United States and Switzerland said preliminary results reveal deforestation has increased in parts of Colombia by 340 per cent since 2004, and more than 2.5 million acres of forest have been lost in the Gran Chaco region of Paraguay, the second largest forested area in South America. The satellite-based system, dubbed Terra-I, uses data supplied by NASA's MODIS satellite sensor to monitor changes in land cover every 16 days. A challenge for the researchers was separating real human-induced changes, such as deforestation, from changes brought about by natural seasonality and by droughts or floods. "We developed a computational neural network and 'trained' it with data from 2000-2004 to recognize the normal changes in vegetation greenness due to seasonal variation in rainfall in different areas," Mark Mulligan of King's College London said. "The network now recognizes where and when greenness suddenly changes well beyond these normal limits as a result of deforestation," he said in a UCL release Tuesday. "The system runs on data for every 250 square meters of land from Mexico to Argentina shortly after the data comes in from MODIS and highlights every 16 days the pixels that significantly change, writing these results to Google Maps for easy visualization," he said.