Study Notes on Roads and Deforestation in Amazon

Roads and Deforestation in the Amazon: Overview and Findings

  • Authors: Christopher P. Barber, Mark A. Cochrane, Carlos M. Souza Jr., William F. Laurance

  • Institutions:

    • South Dakota State University

    • Instituto do Homem e Meio Ambiente da Amazônia (Imazon)

    • James Cook University

Article Information

  • History:

    • Received: 8 March 2014

    • Revised: 30 June 2014

    • Accepted: 6 July 2014

    • Available online: 1 August 2014

  • Keywords: Amazon, Roads, Protected areas, Conservation, Deforestation, Tropical forests

Abstract

  • Roads significantly impact deforestation in the Amazon.

  • The study assesses past deforestation relative to highway, river, and unofficial road networks.

  • Results indicate that deforestation occurs predominantly within 5.5 km of roads and 1 km of rivers: 95% of deforestation is within these proximities.

  • Protected areas (PAs) near roads and rivers show much lower deforestation rates (10.9%) compared to unprotected areas (43.6%).

  • Estimated deforestation avoided due to PAs: 39,462 km²; if PAs only displace deforestation, the estimate is 34,501 km².

  • Conclusion: Unofficial roads are critical drivers of deforestation; PAs reduce but do not fully prevent deforestation risk.

Introduction

  • The Brazilian Amazon contains a third of the world’s tropical forests, sustaining approximately 13% of global biodiversity (Lewinsohn and Prado, 2005).

  • Total area of moist tropical forests: ~4 million km²; 90% was formerly forested (Olson et al., 2001).

  • Deforestation rates: 0.52% per year (18,857 km² annually) during the 1990s and 2000s (INPE, 2009).

  • As of 2009, ~18% of forests converted to other land uses (Pereira et al., 2010).

  • Deforestation dynamics are most significant near transportation routes (Laurance et al., 2009; Alves, 2002 talks about 90% of deforestation near major roads).

Transportation Networks and Deforestation

  • Official Roads: 73,553 km in Brazilian Amazon, classified based on federal/state designations.

  • Unofficial Roads: Rapidly expanding in the Amazon, mostly for logging and colonization, leading to ecological degradation (Arima et al. 2005).

    • Reported new road growth of >40 km per 10,000 km² annually (Brandão and Souza, 2006).

  • Navigable Rivers: Another access mode contributing to deforestation, often neglected in analyses (Peres and Terborgh, 1995).

Protected Areas (PAs) in the Amazon

  • Established to conserve biodiversity and protect portions of the 23 Amazonian ecoregions (Rylands and Brandon, 2005).

  • By 2006, 1.8 million km² (45% of the Amazon) under some level of protection.

    • Types of PAs:

    • Strictly Protected Areas (19.2%): Aimed at biodiversity conservation.

    • Sustainable Use Areas (30.6%): Allow resource extraction.

    • Indigenous Reserves: Prevent large-scale deforestation.

  • PAs classified into two groups:

    • Threatened Lands: Actively resist development.

    • Remotely Located Lands: Defaultly protected due to lack of accessibility.

  • Studies indicate that PAs generally slow development pressure and deforestation (Barber et al., 2012; Nepstad et al., 2006).

Methods

Study Area

  • Spatial relationships examined between transportation networks and deforestation within the Brazilian Amazon.

Data Sources

  • Road/river datasets: From IBGE, included both official and unofficial roads contributing a total of 264,058 km networks for the study.

  • Land Cover Data: Provided by INPE PRODES project mapping Amazonian deforestation since 1997.

Transportation Network Influence

  • Used distances of 50 km and 100 km for highway evaluations based on past studies, with observed deforestation attributed to road proximity.

  • Effective distances for deforestation impacts calculated accurately (5.5 km for all roads, 1.0 km for navigable rivers).

Results

Deforestation Trends

  • By 2006, 476,925 km² of forest cleared in the Brazilian Amazon; 85.5% of cleared areas within 50 km of highways, increasing to 95.5% within 100 km.

  • Accessibility: 35.2% of the Amazon, encompassing 94.9% of deforestation.

  • Protected Areas Performance: 10.9% forest loss within PAs vs. 43.6% in unprotected lands.

Expected Deforrestation Scenarios in PAs

  • Prevention Scenario: Expectation of clearing due to accessibility similar to unprotected lands resulted in 61,792 km² potential clearing within PAs.

  • Displacement Scenario: Redistribution of expected deforestation across land types yielded 56,831 km² expected clearing, suggesting 34,500 km² would have been displaced from PAs to unprotected areas due to their protective status.

Discussion and Implications

  • Protected areas cannot fully insulate against deforestation risks; best practices involve managing accessibility and ongoing monitoring.

  • REDD+ initiatives can be effective if they recognize both deforestation prevention and displacement scenarios.

  • Careful governance of expanding road networks is critical to biodiversity conservation in the Amazon.

Conclusion

  • 94.9% of deforestation linked to proximity to roads/rivers.

  • Less than 1.5% of protected forest cleared.

  • Significant reductions in deforestation rates in protected areas underscore their vital role in conservation efforts in accessible Amazonian regions.