Frontier Governance in Amazonia

Enhanced online at www.sciencemag.org/cgi/ content/full/295/5555/629 the business-as-usual scenario of frontier expansion may provoke rapid deforestation, releasing several billion tons of carbon to the atmosphere, while increasing the occurrence of accidental forest fire, species loss, and deforestationdriven rainfall inhibition (1, 2). However, economic development is vital, as most of the 17 million people in this region earn less than USSlOO per month. We interpret many of the infrastructure investments (including road paving and river channelization) as inevitable, and the primary challenge as one of strengthening frontier management in the region. Recent trends in Brazil's land-use regulation and management capacity could potentially conserve 70 to 80% of the forest while fostering economic development. These fragile gains are threatened by institutional weaknesses and rural violence, but could presage unprecedented large-scale tropical forest conservation if sustained and strengthened. A regional conservation strategy that builds on the conventional emphasis on parks and reserves and seeks to maintain most of the land forested is urgently needed. Large-scale forest conservation is essential because of the tight coupling between the Amazon rainforest (only 15% of which is deforested) and the regional climate system; continued transformation to pasture and cropland could disrupt the