15.05.2017 | permalink
Large-scale commercial agriculture has been the main driver of deforestation in the tropics, new research shows. Clearings for large-scale agricultural expansion were responsible for an increasing proportion – in some places, more than half – of all observed forest loss across the tropics between 2000 and 2012, according to a study published in the journal Environmental Research Letters. The team of scientists at Duke University in North Carolina analysed deforestation trends by clearing size for this 12-year-period, using high-resolution, satellite-derived maps of forest cover produced by the University of Maryland. They found that Southeast Asia and South America saw the most severe losses. Over the study period, 79% of deforestation in the tropics occurred in these regions. “In South America, more than 60% of the increase in deforestation was due to a growing number of medium- and large-sized forest clearings typical of what you see with industrial-scale commercial agricultural activities,” said Jennifer J. Swenson, associate professor at Duke’s Nicholas School of the Environment. In Southeast Asia, losses increased from 1400 kha in 2001 to more than 3700 kha in 2012.
Brazil, which had stricter policies limiting agricultural expansion until 2012, was the only country showing a reverse trend. Average annual deforestation decreased from approximately 3000 kha to 2150 kha between the first and second halves of the study period. “This unique trend may be short-lived, however, given Brazil’s relaxed forest policies of the last few years,” Swenson added. According to the researchers, the emerging prominence of large-scale drivers of forest loss in many regions and countries, in particular Indonesia, Malaysia, Cambodia, Paraguay and Bolivia, suggests the growing need for policy interventions which target industrial-scale agricultural commodity producers. Small-scale farmers also contribute to forest clearings but to a smaller extent. “A small family farm that produces sustenance crops or food for local consumption typically causes less than 10 hectares - or just under 25 acres - of land to be cleared per year,” said co-author Kemen G. Austin. “These small clearings can have relatively modest impacts on biodiversity, habitat connectivity, carbon storage, water quality, erosion control and other vital ecosystem services the forest provides.” By comparison, an industrial-scale plantation - such as one that grows and processes palm oil or soybeans for the global market - can cause nearly 2,500 acres of land to be cleared annually. As the size of the cleared land increases, so do the scale and scope of the potential ecological impacts, the study warns. (ab)