Roads, deforestation, and the mitigating effect of protected areas in the Amazon

Roads have a major impact on Amazon deforestation. However, the effects of the rapidly growing network of illegal or unofficial roads in the Amazon are usually not considered. We assessed relationships between past deforestation and existing networks of highways, navigable rivers, and all other roads, including more than 190,000 km of unofficial roads. We found that deforestation was much higher near roads and rivers than elsewhere in the Amazon; nearly 95% of all deforestation occurred within 5.5 km of roads or 1 km of rivers. Protected areas near roads and rivers had much lower deforestation (10.9%) than did unprotected areas near roads and rivers (43.6%). If one assumes that existing protected areas halt deforestation, then we estimate that 39,462 km2 of expected forest clearing would have been avoided. However, if one assumes that protected areas merely displace deforestation to other locations, then we estimate that 34,501 km2 of expected clearing would have been displaced elsewhere. We conclude that proximity to transportation networks, particularly the rapidly growing unofficial road network, is a major proximate driver of deforestation in Amazonia and that protected areas are having a strong mitigating effect on that risk.