Deforestation: Carving up the Amazon
A rash of road construction is causing widespread change in the world's largest tropical forest — with potentially global consequences.
Barbara Fraser
http://www.nature.com/polopoly_fs/7.17454.1400581296!/image/Amazon.jpg_gen/derivatives/landscape_630/Amazon.jpg
Next to a newly paved highway in the Peruvian Amazon, a discreet white-on-green sign urges travellers to protect the surrounding ecosystem. “Let's care for the environment, let's conserve the forest,” it reads. But the appeal comes too late for this spot in the region known as Madre de Dios. Before the route was paved a few years ago, tall trees lined the roadside, but the forest edge here now lies about half a kilometre away, beyond a jumble of underbrush and freshly cut trees where a cattle pasture was recently carved out of the woods.
As drivers head east and enter Brazil, the view is much the same for hundreds of kilometres. Such is the impact of the Interoceanic Highway, a route some 5,500 kilometres long that cuts clear across South America.
The highway is just one strand in a web of roads that now criss-cross the Amazon. So far, most have encroached on forest around the edges of the basin, but they are increasingly slicing through the middle. In Brazil alone, the Amazon road system grew by an average of almost 17,000 kilometres a year between 2004 and 2007 (ref. 1). Across the basin, estimates for the total length of roads vary widely from about 100,000 to 190,000 kilometres of paved and dirt roads cutting through the Amazon.
Once construction begins, road crews are quickly followed by land speculators, loggers, farmers, ranchers, gold miners and others who carve away the forest along the route. That activity leaves obvious scars on the landscape in the form of treeless expanses, but research is now showing that the building of roads also triggers a cascade of environmental changes in the remaining forest that can dry out trees, set the stage for wildfires and weaken the ecosystem.
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http://www.nature.com/news/deforestation-carving-up-the-amazon-1.15269
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before the planet.
