A global strategy for road building

Journal name:
Nature
Volume:
513,
Pages:
229–232
Date published:
DOI:
doi:10.1038/nature13717
Received
Accepted
Published online

The number and extent of roads will expand dramatically this century1. Globally, at least 25 million kilometres of new roads are anticipated by 2050; a 60% increase in the total length of roads over that in 2010. Nine-tenths of all road construction is expected to occur in developing nations1, including many regions that sustain exceptional biodiversity and vital ecosystem services. Roads penetrating into wilderness or frontier areas are a major proximate driver of habitat loss and fragmentation, wildfires, overhunting and other environmental degradation, often with irreversible impacts on ecosystems2, 3, 4, 5. Unfortunately, much road proliferation is chaotic or poorly planned3, 4, 6, and the rate of expansion is so great that it often overwhelms the capacity of environmental planners and managers2, 3, 4, 5, 6, 7. Here we present a global scheme for prioritizing road building. This large-scale zoning plan seeks to limit the environmental costs of road expansion while maximizing its benefits for human development, by helping to increase agricultural production, which is an urgent priority given that global food demand could double by mid-century8, 9. Our analysis identifies areas with high environmental values where future road building should be avoided if possible, areas where strategic road improvements could promote agricultural development with relatively modest environmental costs, and ‘conflict areas’ where road building could have sizeable benefits for agriculture but with serious environmental damage. Our plan provides a template for proactively zoning and prioritizing roads during the most explosive era of road expansion in human history.

At a glance

Figures

  1. The distribution of major roads globally.
    Figure 1: The distribution of major roads globally.

    Roads are indicated in black; white areas lack mapped roads. The quality of road maps varies greatly among nations, with many smaller and unofficial roads remaining unmapped. We generated this map using data from the integrated gROADS database (http://sedac.ciesin.columbia.edu/data/set/groads-global-roads-open-access-v1; accessed 7 June 2014); Center for International Earth Science Information Network - CIESIN - Columbia University, and Information Technology Outreach Services - ITOS - University of Georgia. 2013. Global Roads Open Access Data Set, Version 1 (gROADSv1). Palisades, NY: NASA Socioeconomic Data and Applications Center (SEDAC). http://dx.doi.org/10.7927/H4VD6WCT.

  2. The environmental-values and road-benefits layers.
    Figure 2: The environmental-values and road-benefits layers.

    a, b, The environmental-values layer (a) integrates data on terrestrial biodiversity, key habitats, wilderness, and environmental services. The road-benefits layer (b) shows areas broadly suitable for agricultural intensification, where new roads or road improvements could potentially promote increased production. See Supplementary Information for data sources.

  3. A global roadmap.
    Figure 3: A global roadmap.

    Shown are priority road-free areas (green shades), priority agricultural areas (red shades), conflict areas (dark shades), and lower-priority areas (light shades). Values of the environmental-values and road-benefits layers are each divided into deciles, yielding 100 unique colour combinations. See Supplementary Information for details and data sources.

  4. Mapped roads overlaid onto the roads-benefits layer.
    Figure 4: Mapped roads overlaid onto the roads-benefits layer.

    a, b, In eastern Africa (a) and Siberia (b), roads are rapidly expanding into relatively road-free areas, but for different reasons. Narrow black lines indicate mapped roads. In both regions, areas with darker-red colours have greater agricultural potential than those with lighter colours. See Supplementary Information for data sources.

  5. Roadmaps for northern South America and Sub-Saharan Africa.
    Extended Data Fig. 1: Roadmaps for northern South America and Sub-Saharan Africa.

    Magnified images such as these could be integrated with local-scale data to facilitate actual road planning. Values of the environmental-values and road-benefits layers are each divided into deciles, yielding 100 unique colour combinations. See Supplementary Information for data sources.

References

  1. Dulac, J. Global Land Transport Infrastructure Requirements: Estimating Road and Railway Infrastructure Capacity and Costs to 2050 (International Energy Agency, 2013)
  2. Laurance, W. F. et al. The future of the Brazilian Amazon. Science 291, 438439 (2001)
  3. Blake, S. et al. Forest elephant crisis in the Congo Basin. PLoS Biol. 5, e111 (2007)
  4. Laurance, W. F., Goosem, M. & Laurance, S. G. Impacts of roads and linear clearings on tropical forests. Trends Ecol. Evol. 24, 659669 (2009)
  5. Adeney, J. M., Christensen, N. & Pimm, S. L. Reserves protect against deforestation fires in the Amazon. PLoS ONE 4, e5014 (2009)
  6. Fearnside, P. M. & Graça, P. BR-319: Brazil’s Manaus-Porto Velho Highway and the potential impact of linking the arc of deforestation to central Amazonia. Environ. Manage. 38, 705716 (2006)
  7. Forman, R. T. T. et al. Road Ecology: Science and Solutions (Island Press, 2003)
  8. Tilman, D., Cassman, K. G., Matson, P. A., Naylor, R. & Polasky, S. Agricultural sustainability and intensive production practices. Nature 418, 671677 (2002)
  9. Tilman, D. et al. Forecasting agriculturally driven global environmental change. Science 292, 281284 (2001)
  10. Perz, S. G. et al. Regional integration and local change: road paving, community connectivity and social-ecological resilience in a tri-national frontier, southwestern Amazonia. Reg. Environ. Change 12, 3553 (2012)
  11. Weng, L. et al. Mineral industries, growth corridors and agricultural development in Africa. Glob. Food Security 2, 195202 (2013)
  12. Boakes, E. H., Mace, G. M., McGowan, P. J. K. & Fuller, R. A. Extreme contagion in global habitat clearance. Proc. R. Soc. Lond. B 277, 10811085 (2010)
  13. Laurance, W. F. & Balmford, A. A global map for road building. Nature 495, 308309 (2013)
  14. Bradshaw, C. J. A., Warkentin, I. G. & Sodhi, N. S. Urgent preservation of boreal carbon stocks and biodiversity. Trends Ecol. Evol. 24, 541548 (2009)
  15. Laporte, N. T., Stabach, J. A., Grosch, R., Lin, T. S. & Goetz, S. J. Expansion of industrial logging in central Africa. Science 316, 1451 (2007)
  16. Mueller, N. D. et al. Closing yield gaps through nutrient and water management. Nature 490, 254257 (2012)
  17. Weinhold, D. & Reis, E. Transportation costs and the spatial distribution of land use in the Brazilian Amazon. Glob. Environ. Change 18, 5468 (2008)
  18. Rudel, T. K., DeFries, R., Asner, G. P. & Laurance, W. F. Changing drivers of deforestation and new opportunities for conservation. Conserv. Biol. 23, 13961405 (2009)
  19. Phalan, B., Onial, M., Balmford, A. & Green, R. E. Reconciling food production and biodiversity conservation: Land sharing and land sparing compared. Science 333, 12891291 (2011)
  20. Barber, C. P., Cochrane, M. A., Souza, C. M., Jr & Laurance, W. F. Roads, deforestation, and the mitigating effect of protected areas in the Amazon. Biol. Conserv. 177, 203209 (2014)
  21. Gullett, W. Environmental impact assessment and the precautionary principle: Legislating caution in environmental protection. Australas. J. Environ. Manage. 5, 146158 (1998)
  22. Laurance, W. F. Forest destruction: the road to ruin. New Sci. 194 25 (2007) http://www.newscientist.com/article/mg19426075.600-forest-destruction-the-road-to-ruin.html
  23. Lawrence, D. P. Environmental Impact Assessment: Practical Solutions to Recurrent Problems (John Wiley & Sons, 2003)
  24. Laurance, W. F. et al. Averting biodiversity collapse in tropical forest protected areas. Nature 489, 290294 (2012)
  25. Caro, T., Dobson, A., Marshall, A. J. & Peres, C. A. Compromise solutions between conservation and road building in the tropics. Curr. Biol. 24, R722R725 (2014)
  26. Warner, E. et al. Modeling biofuel expansion effects on land use change dynamics. Environ. Res. Lett. 8, 015003 (2013)
  27. Campbell W. B., López Ortíz S., eds. Integrating Agriculture, Ecotourism, and Conservation: Examples from the Field (Springer, 2011)
  28. Challinor, A. J. et al. A meta-analysis of crop yield under climate change and adaptation. Nature Clim. Chang. 4, 287291 (2014)
  29. Edwards, D. P. et al. Mining and the African environment. Conserv. Lett. 7, 302311 (2014)
  30. Balmford, A., Green, R. & Phalan, B. What conservationists need to know about farming. Proc. R. Soc. Lond. B 279, 27142724 (2012)

Download references

Author information

Affiliations

  1. Centre for Tropical Environmental and Sustainability Science, and College of Marine and Environmental Sciences, James Cook University, Cairns, Queensland 4878, Australia

    • William F. Laurance,
    • Gopalasamy Reuben Clements,
    • Sean Sloan,
    • Miriam Goosem &
    • Oscar Venter
  2. Kenyir Research Institute, Universiti Malaya Terengganu, 21030 Kuala Terengganu, Malaysia

    • Gopalasamy Reuben Clements
  3. Institute on the Environment, and Department of Ecology, Evolution, and Behavior, University of Minnesota, Saint Paul, Minnesota 55108, USA

    • Christine S. O’Connell
  4. Center for the Environment, Harvard University, Cambridge, Massachusetts 02138, USA

    • Nathan D. Mueller
  5. Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK

    • David P. Edwards
  6. Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK

    • Ben Phalan &
    • Andrew Balmford
  7. Australian Research Centre for Urban Ecology, and School of Botany, University of Melbourne, Melbourne, Victoria 3010, Australia

    • Rodney Van Der Ree
  8. Conservation Strategy Fund, 663-2300 Curridabat, San José, Costa Rica

    • Irene Burgues Arrea

Contributions

W.F.L. and A.B. initially conceived the study, and W.F.L. coordinated its design, analysis, and manuscript preparation. G.R.C. and S.S. conducted the spatial analyses; C.S.O., N.D.M., O.V., G.R.C., S.S. and B.P. generated or collated key datasets; and M.G., D.P.E., R.V.D.R. and I.B.A. provided ideas and critical feedback.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

Author details

Extended data figures and tables

Extended Data Figures

  1. Extended Data Figure 1: Roadmaps for northern South America and Sub-Saharan Africa. (528 KB)

    Magnified images such as these could be integrated with local-scale data to facilitate actual road planning. Values of the environmental-values and road-benefits layers are each divided into deciles, yielding 100 unique colour combinations. See Supplementary Information for data sources.

Supplementary information

PDF files

  1. Supplementary information (2.3 MB)

    This file contains Supplementary Text, Supplementary Figures 1-18 and Supplementary References.

Comments

  1. Report this comment #64123

    Jeffrey Wells said:

    Road building a problem even in developed countries

    Conservationists working in developed countries, especially in northern and temperate regions, should not be lulled by global scale analyses into assuming that the issue of the building of roads and other infrastructure and the conflicts that result are not a major question for the future of remaining primary intact forest, wetlands, and other habitats. Construction of new roads and other infrastructure (railroads, electricity transmission lines) is a globally important driver of loss of biodiversity, carbon stores, carbon sequestrating ecosystems, and other forms of natural capital as highlighted by William Laurance et al. (A global strategy for road building, Nature doi:10.1038/nature13717; 2014). Although it is a particularly striking problem in undeveloped, tropical countries, it is still a major problem even in developed countries like Canada where vast areas remain quite pristine.

    The Boreal Forest region of Canada holds an estimated 25% of the world?s primary forests (forest areas free of the footprint of large-scale industry) and the massive carbon stores within them. Yet a vast network of hundreds of thousands of kilometers of logging roads now spans Canada?s southern Boreal Forest region?at least 51,000 km (ten times the driving distance between Montreal and Vancouver) in Quebec alone and tens of thousands more km of new roads, railroads, and transmission lines are proposed across the rest of northern Canada. Much of this infrastructure is in support of mining and oil and gas industries. Over time, wilderness areas are fragmented and ecosystem function diminished on a road-by-road and power line-by-power-line basis, with insufficient effort given to the maintenance of intact habitat blocks or functioning units.

    There is an urgent need, even in developed countries, for governments to adopt landscape-level land-use planning that incorporates modeling of cumulative effects from multiple industrial land-uses to prevent unnecessary fragmentation and degradation of habitat and allow protection of important ecological features and functions.

    Jeffrey V. Wells, International Boreal Conservation Campaign, Seattle, WA, USA

    Nigel T. Roulet, Department of Geography, McGill University, Montreal, Quebec, Canada

    David W. Schindler, Department of Biological Sciences, University of Alberta , Edmonton, Alberta, Canada

  2. Report this comment #64445

    Abi Vanak said:

    Potholes in the global-road map ? Response to Laurance et al.

    Authors:
    A.T. Vanak^1, 2*^, K. K. Karanth^3,4,5^, S. Hedges^3^, E. Di Minin^2, 7^, R. Slotow^2, 8^, M. Thaker^9^, K. Shanker^9^, N. Rai^1^, M. J. Tyson^10^, J. Krishnaswamy^1^, U. Ramakrishanan^11^, K. U. Karanth^12,5^

    Laurance et al.1 have developed a composite global map to identify areas where new roads will lead to the greatest environmental damage, and areas that would benefit from road expansion. Prioritization for environmental impact avoidance is important, but must be robust enough for context specific application. Multiple problems in the current analysis however, invalidate this strategy for road planning. These include a mismatch of scale between global patterns of biodiversity and the requirements for informed planning, poor quality of global datasets, lack of complementarity analyses, and side-lining of regional conservation priorities. Furthermore, by overemphasizing the importance of agriculture relative to other commercial activities, the authors ignore regional economic drivers of road building^2^. All these shortcomings hamper any potential down-scaling to a national or regional level ? the scale at which roads are planned ? and could have serious ramifications for biodiversity conservation and development planning if inappropriately applied.

    Laurance et al. readily acknowledge that road planning occurs at smaller scales and that the drivers and environmental impacts will vary across contexts. However, in their analysis, environmental layers include coarse-scale global datasets that are notoriously incomplete and inaccurate [e.g. World Database on Protected Areas (PAs)3], or are broad estimations of species distributions across large areas (e.g. IUCN range maps, plant species estimations). Their downscaling to a finer resolution is not supported by the underlying data^4^, and will almost certainly result in serious commission and omission errors. Without sensitivity analyses to determine model robustness to changes in the underlying inputs^4^, we have no estimate of how downscaling exacerbates these biases. Laurance et al. also weight all biodiversity layers equally, but roads have different effects on various components of biodiversity: exacerbating poaching threats for some species, fragmenting ranges for others, and so on^5,6^. Furthermore, by failing to incorporate complementarity analyses, the authors invariably overemphasize species-rich areas regardless of local and regional conservation priorities, a well-known issue in conservation planning^7^.

    Laurance et al. are correct in prioritizing PAs as relatively road free, but in areas of fragmented land-use, PAs are often too small to hold viable populations of globally endangered species, such as tigers and elephants^8,9^. The authors also preclude alternate conservation and production approaches, such as a biodiversity-friendly multiple-use landscape matrix^10^. These areas provide habitat as well as corridors for connectivity for protected and natural areas, especially considering species range shifts to changing climate^11^.

    Laurance et al. also seemingly ignore the circularity in their principal economic argument of road-mediated agricultural intensification: i.e. areas that have lost most of their natural vegetation to intensive agriculture are also those that already have the highest density of roads, highest rates of application of fertilizer and irrigation, and are already producing amongst the highest output of agricultural products in the world^12^. By weighting these areas, they invariably bias the resulting map towards further road intensification. Indeed, for several of the road ?hotspot? countries (e.g. India), projected agricultural increases are close to zero (See Suppl. Fig. 15 in Laurance et al.) and thus further road intensification is moot. Some of the greatest emerging threats to biodiversity in many countries are from the growth of industry, mines and infrastructure, and incorporating these would have resulted in a more realistic prioritization for road expansion.

    Although Laurence et al. claim to provide ?an important first-step towards strategic road planning?1, visual down-scaling reveals inconsistencies between their prioritizations and on-ground realities. For example, they over-predict the biodiversity value of large tracts of oil palm plantations in Malaysia and Indonesia, thus classifying them as areas of conflict with high road benefits (Fig. 1 ). Strangely, Singapore, amongst the most densely populated countries in the world, is prescribed as biodiverse where road expansion should be avoided (Fig. 1 ). On the other hand, large parts of India are shown as hotspots for road development, deprioritizing habitats such as semi-arid savannas^13^, and ignoring areas of customary conservation practice^14^ that can potentially result in isolating many PAs and severing connectivity 15.

    Ideally, such an analysis of road planning should be an aggregation of local and regional studies that combine the best available data on road-networks, local biodiversity values, and detailed land-cover/land-use maps that capture the potential of the landscape to support both biodiversity as well as movement of wide-ranging species. In the hands of politicians and policy makers who have little regard for biodiversity, Laurence et al.'s global-scale analysis can result in harmful policy recommendations and could irreversibly compromise sustainable biodiversity conservation that incorporates local-scale development planning.

    Affiliations
    ^1^Ashoka Trust for Research in Ecology and the Environment, Bangalore, India
    ^2^School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
    ^3^Wildlife Conservation Society, Global Conservation Programs, New York, USA
    ^4^School of Geography, Planning and Environmental Management, University of Queensland, St Lucia, Australia
    ^5^Centre for Wildlife Studies, Bangalore, India
    ^6^Duke University, Durham, USA
    ^7^Finnish Centre of Excellence in Metapopulation Biology, Department of Biosciences, University of Helsinki, 00014, Helsinki, Finland
    ^8^Department of Genetics, Evolution and Environment, Faculty of Life Sciences, University College London, London, United Kingdom.
    ^9^Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
    ^10^Wildlife Conservation Society ? Asia Program, New York, USA
    ^11^National Centre for Biological Sciences, Bangalore, India
    ^12^Wildlife Conservation Society, New York, USA

    ^*^Corresponding Author: A. T. Vanak, (avanak@atree.org)

    References

    1 Laurance, W. F. et al. A global strategy for road building. Nature 513, 229-232 (2014).
    2 Caro, T., Dobson, A., Marshall, A. J. & Peres, C. A. Compromise solutions between conservation and road building in the tropics. Curr. Biol. 24, R722-R725 (2014).
    3 Visconti, P. et al. Effects of errors and gaps in spatial data sets on assessment of conservation progress. Conserv. Biol. 27, 1000-1010 (2013).
    4 Hurlbert, A. H. & Jetz, W. Species richness, hotspots, and the scale dependence of range maps in ecology and conservation. Proc. Nat. Acad. Sci. 104, 13384-13389 (2007).
    5 Forman, R. T. & Alexander, L. E. Roads and their major ecological effects. Annu. Rev. Ecol. Syst., 207-C202 (1998).
    6 Trombulak, S. C. & Frissell, C. A. Review of ecological effects of roads on terrestrial and aquatic communities. Conserv. Biol. 14, 18-30 (2000).
    7 Margules, C. R. & Pressey, R. L. Systematic conservation planning. Nature 405, 243-253 (2000).
    8 Watson, J. E. M., Dudley, N., Segan, D. B. & Hockings, M. The performance and potential of protected areas. Nature (In press).
    9 Leimgruber, P. et al. Fragmentation of Asia's remaining wildlands: implications for Asian elephant conservation. Anim. Conserv. 6, 347-359 (2003).
    10 UNCTAD. Trade and Environment Review 2013: Wake Up Before It?s Too Late. (United Nations, 2013).
    11 Watson, J. E., Iwamura, T. & Butt, N. Mapping vulnerability and conservation adaptation strategies under climate change. Nature Climate Change (2013).
    12 Foley, J. A. et al. Solutions for a cultivated planet. Nature 478, 337-342 (2011).
    13 Dutta, S. & Jhala, Y. Planning agriculture based on landuse responses of threatened semiarid grassland species in India. Biol. Conserv. 175, 129-139 (2014).
    14 Kothari, A., Corrigan, C., Jonas, H., Neumann, A. & Shrumm, H., (eds) Recognising and Supporting Territories and Areas Conserved By Indigenous Peoples And Local Communities: Global Overview and National Case Studies. Vol. Technical Series no. 64 160 (Secretariat of the Convention on Biological Diversity, ICCA Consortium, Kalpavriksh, and Natural Justice, Montreal, Canada. , 2012).
    15 Joshi, A., Vaidyanathan, S., Mondol, S., Edgaonkar, A. & Ramakrishnan, U. Connectivity of tiger (Panthera tigris) populations in the human-influenced forest mosaic of central India. PloS one 8, e77980 (2013).

Subscribe to comments

Additional data