Skip to main content
SpringerLink
Log in

Ghost roads and the destruction of Asia-Pacific tropical forests

  • Article
  • Published:

From Nature

View current issue Submit your manuscript

A Publisher Correction to this article was published on 15 May 2024

This article has been updated

Abstract

Roads are expanding at the fastest pace in human history. This is the case especially in biodiversity-rich tropical nations, where roads can result in forest loss and fragmentation, wildfires, illicit land invasions and negative societal effects1,2,3,4,5. Many roads are being constructed illegally or informally and do not appear on any existing road map6,7,8,9,10; the toll of such ‘ghost roads’ on ecosystems is poorly understood. Here we use around 7,000 h of effort by trained volunteers to map ghost roads across the tropical Asia-Pacific region, sampling 1.42 million plots, each 1 km2 in area. Our intensive sampling revealed a total of 1.37 million km of roads in our plots—from 3.0 to 6.6 times more roads than were found in leading datasets of roads globally. Across our study area, road building almost always preceded local forest loss, and road density was by far the strongest correlate11 of deforestation out of 38 potential biophysical and socioeconomic covariates. The relationship between road density and forest loss was nonlinear, with deforestation peaking soon after roads penetrate a landscape and then declining as roads multiply and remaining accessible forests largely disappear. Notably, after controlling for lower road density inside protected areas, we found that protected areas had only modest additional effects on preventing forest loss, implying that their most vital conservation function is limiting roads and road-related environmental disruption. Collectively, our findings suggest that burgeoning, poorly studied ghost roads are among the gravest of all direct threats to tropical forests.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1: Road density in the tropical Asia-Pacific region is much higher than indicated by available global datasets.
Fig. 2: Environmental and socioeconomic features that influence forest loss across the tropical Asia-Pacific region.
Fig. 3: Effects of protected areas in limiting road construction and forest loss.
Fig. 4: Roads usually precede deforestation.
Fig. 5: Two versions of the human footprint for eastern and central Borneo, using data from 2020.

Similar content being viewed by others

Data availability

The datasets used for this study (including comprehensive road maps as a raster of road density at 1-km2 resolution) are available in the Supplementary Information, on request to J.E.E. and W.F.L. or as follows. OpenStreetMap data are available from https://download.geofabrik.de/, and GRIP road data from https://www.globio.info/download-grip-dataset. National and subnational administrative-region data were obtained from GADM (https://gadm.org/). Population-density data were from WorldPop (https://www.worldpop.org/). GDP data were accessed at https://datadryad.org/stash/dataset/doi:10.5061/dryad.dk1j0. Protected-area data were from Protected Planet (https://www.protectedplanet.net/en). Waterways locations were obtained from the Global River Widths from Landsat Database (https://zenodo.org/records/1297434). Elevation data were accessed at http://srtm.csi.cgiar.org, and rainfall data at https://doi.org/10.16904/envidat.211. Data for all soil variables were obtained from Soil Grids (https://soilgrids.org/).

Change history

References

  1. Dulac, J. Global Land Transport Infrastructure Requirements: Estimating Road and Railway Infrastructure Capacity and Costs to 2050 (International Energy Agency, Paris, 2013).

  2. Laurance, W. F. et al. A global strategy for road building. Nature 513, 229–232 (2014).

    Article  ADS  CAS  PubMed  Google Scholar 

  3. Ascensão, F. et al. Environmental challenges for the Belt and Road Initiative. Nat. Sustain. 1, 206–209 (2018).

    Article  Google Scholar 

  4. Kleinschroth, F. et al. Road expansion and persistence in forests of the Congo Basin. Nat. Sustain. 2, 628–634 (2019).

    Article  Google Scholar 

  5. Ibisch, P. L. et al. A global map of roadless areas and their conservation status. Science 354, 1423–1427 (2016).

    Article  ADS  CAS  PubMed  Google Scholar 

  6. 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, 203–209 (2014).

    Article  Google Scholar 

  7. Laurance, W. F., Goosem, M. & Laurance, S. G. Impacts of roads and linear clearings on tropical forests. Trends Ecol. Evol. 24, 659–669 (2009).

    Article  PubMed  Google Scholar 

  8. Alamgir, M. et al. Economic, socio-political and environmental risks of road development in the tropics. Curr. Biol. 27, 1130–1140 (2017).

    Article  Google Scholar 

  9. Fearnside, P. M. in Handbook of Road Ecology (eds van der Ree, R. et al.) 414–424 (John Wiley & Sons, 2015).

  10. Hughes, A. C. Have Indo-Malaysian forests reached the end of the road? Biol. Conserv. 223, 129–137 (2018).

    Article  Google Scholar 

  11. Schrieber-Gregory, D. Regulation Techniques for Multicollinearity: Lasso, Ridge, and Elastic Nets https://www.lexjansen.com/wuss/2018/131_Final_Paper_PDF.pdf (2018).

  12. Hettige, H. When Do Rural Roads Benefit the Poor and How? An In-Depth Analysis (Asian Development Bank, 2006).

  13. Laurance, W. F. et al. The future of the Brazilian Amazon. Science 291, 438–439 (2001).

    Article  CAS  PubMed  Google Scholar 

  14. Vilela, T. et al. A better Amazon road network for people and the environment. Proc. Natl Acad. Sci. USA 117, 7095–7102 (2020).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  15. van der Ree, R., Smith, D. & Grilo, C. (eds) Handbook of Road Ecology (John Wiley & Sons, 2015).

  16. Bebbington, A. et al. Priorities for governing large-scale infrastructure in the tropics. Proc. Natl Acad. Sci. USA 117, 21829–21833 (2020).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  17. Meijer, J. R., Huijbregts, M. A. J., Schotten, K. C. G. J. & Schipper, A. M. Global patterns of current and future road infrastructure. Environ. Res. Lett. 13, 064006 (2018).

    Article  ADS  Google Scholar 

  18. Ramm, F., Topf, J. & Chilton, S. OpenStreetMap: Using and Enhancing the Free Map of the World (UIT Cambridge, 2010).

  19. Laurance, W. F. et al. Reducing the global environmental impacts of rapid infrastructure expansion. Curr. Biol. 25, 259–262 (2015).

    Article  Google Scholar 

  20. Sloan, S. et al. Infrastructure development and contested forest governance threaten the Leuser Ecosystem, Indonesia. Land Use Policy 77, 298–309 (2018).

    Article  Google Scholar 

  21. Venter, O. et al. Sixteen years of change in the global terrestrial human footprint and implications for biodiversity conservation. Nat. Commun. 7, 12558 (2016).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  22. Williams, B. A. et al. Change in terrestrial human footprint drives continued loss of intact ecosystems. One Earth 3, 371–383 (2020).

    Article  ADS  Google Scholar 

  23. Watson, J. E. M. et al. Catastrophic declines in wilderness areas undermine global environment targets. Curr. Biol. 26, 2929–2934 (2016).

    Article  CAS  PubMed  Google Scholar 

  24. Curtis, P. G., Slay, C., Harris, N., Tyukavina, A. & Hansen, M. C. Classifying drivers of global forest loss. Science 361, 1108–1111 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  25. Pendrill, F. et al. Agricultural and forestry trade drives large share of tropical deforestation emissions. Glob. Environ. Change 56, 1–10 (2019).

    Article  Google Scholar 

  26. Pendrill, F. et al. Disentangling the numbers behind agriculture-driven tropical deforestation. Science 377, eabm9267 (2022).

    Article  CAS  PubMed  Google Scholar 

  27. Geist, H. J. & Lambin, E. F. Proximate causes and underlying driving forces of tropical deforestation. BioScience 52, 143–150 (2002).

    Article  Google Scholar 

  28. Thünen, J. H. V. The Isolated State in its Relation to Agriculture and National Economy (Pergamon Press, 1966).

  29. Meyfroidt, P. et al. Middle-range theories of land system change. Glob. Environ. Change 53, 52–67 (2018).

    Article  Google Scholar 

  30. Rodrigues, A., Ewers, R., Souza, C., Verissimo, A. & Balmford, A. Boom-and-bust development patterns across the Amazon deforestation frontier. Science 324, 1435–1437 (2009).

    Article  ADS  CAS  PubMed  Google Scholar 

  31. Geldmann, J., Manica, A., Burgess, N. D., Coad, L. & Balmford, A. A global-level assessment of the effectiveness of protected areas at resisting anthropogenic pressures. Proc. Natl Acad. Sci. USA 116, 23209–23215 (2019).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  32. Vancutsem, C. et al. Long-term (1990–2019) monitoring of forest cover changes in the humid tropics. Sci. Adv. 7, eabe1603 (2021).

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  33. Botelho, J., Costa, S., Ribeiro, J. & Souza, C. M. Mapping roads in the Brazilian Amazon with artificial intelligence and Sentinel‐2. Remote Sens. 14, 3625 (2022).

    Article  ADS  Google Scholar 

  34. das Neves, P. et al. Amazon rainforest deforestation influenced by clandestine and regular roadway network. Land Use Policy 108, 105510 (2021).

    Article  Google Scholar 

  35. Cameroon Road Network (World Food Programme, Logistics Cluster, accessed 1 July 2022); https://dlca.logcluster.org/23-cameroon-road-network

  36. Katovai, E., Sirikolo, M., Srinivasan, U., Edwards, W. & Laurance, W. F. Post-logging recovery dynamics and their effects on tree diversity in tropical forests of the Solomon Islands. For. Ecol. Manag. 373, 53–63 (2016).

    Article  Google Scholar 

  37. Qin, S. et al. Protected area downgrading, downsizing, and degazettement as a threat to iconic protected areas. Conserv. Biol. 33, 1275–1285 (2019).

    Article  PubMed  PubMed Central  Google Scholar 

  38. Laurance, W. F. et al. Averting biodiversity collapse in tropical forest protected areas. Nature 489, 290–294 (2012).

    Article  ADS  CAS  PubMed  Google Scholar 

  39. Sloan, S., Bertzky, B. & Laurance, W. F. African development corridors intersect key protected areas. Afr. J. Ecol. 55, 731–737 (2017).

    Article  Google Scholar 

  40. Haddad, N. M. et al. Habitat fragmentation and its lasting impact on Earth’s ecosystems. Sci. Adv. 1, e1500052 (2015).

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  41. Herfort, B., Lautenbach, S., Albuquerque, J., Anderson, J. & Zipf, A. The evolution of humanitarian mapping within the OpenStreetMap community. Sci. Rep. 11, 3037 (2021).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  42. Laurance, W. F. Wanted: AI experts to map road-building boom. Nature 558, 30 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  43. Sloan, S., Talkhani, R. R., Huang, T., Engert J. & Laurance, W. F. Mapping remote roads using artificial intelligence and satellite imagery. Remote Sens. 16, 839 (2024).

  44. Wang, W. et al. A review of road extraction from remote sensing images. J. Traffic Transp. Eng. 3, 271–282 (2016).

    Google Scholar 

  45. De Clerk, E. Facebook uses AI technology to map roads of Thailand. Intelligent Transport https://www.intelligenttransport.com/transport-news/85277/facebook-ai-map-roads-thailand/ (2019).

Download references

Acknowledgements

We thank J. Barlow, R. Chazdon, M. Cochrane, S. Das, M. Goosem, J. Jaeger, P. Negret, C. Souza Jr, R. Talkhani and H. Tao for many helpful comments, and our volunteer road-mappers, including Wild Green Memes for Ecological Fiends, for their efforts. The Australian Research Council, James Cook University and an anonymous philanthropic donor provided support.

Author information

Author notes

  1. Joshua E. Cinner

    Present address: Thriving Oceans Research Hub, School of Geosciences, University of Sydney, Camperdown, New South Wales, Australia

  2. Sean Sloan

    Present address: Department of Geography, Vancouver Island University, Nanaimo, British Columbia, Canada

  3. These authors contributed equally: Jayden E. Engert, Mason J. Campbell

Authors and Affiliations

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

    Jayden E. Engert, Mason J. Campbell, Yoko Ishida, Sean Sloan, Mohammed Alamgir, Jaime Cislowski & William F. Laurance

  2. College of Arts, Society and Education, James Cook University, Townsville, Queensland, Australia

    Joshua E. Cinner

  3. Research Center for Climate Change, and Department of Biology, University of Indonesia, Depok, Indonesia

    Jatna Supriatna

Authors
  1. Jayden E. Engert
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Mason J. Campbell
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Joshua E. Cinner
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Yoko Ishida
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Sean Sloan
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Jatna Supriatna
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Mohammed Alamgir
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Jaime Cislowski
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. William F. Laurance
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

W.F.L., J.E.E., M.J.C., M.A. and S.S. conceived the study; J.E.E., J.E.C. and W.F.L. coordinated data analysis. W.F.L., J.E.E., J.E.C. and M.J.C. wrote the manuscript. J.E.E., Y.I., J.C. and S.S. generated key road datasets. M.J.C., J.E.C., M.A., S.S. and J.S. provided ideas and critical feedback.

Corresponding authors

Correspondence to Jayden E. Engert or William F. Laurance.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature thanks Robin Chazdon, Jochen Jaeger, Pablo Negret and Carlos Souza Jr for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Text, Supplementary Figs. 1–6, Supplementary Tables 1–5 and Supplementary references.

Reporting Summary

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Engert, J.E., Campbell, M.J., Cinner, J.E. et al. Ghost roads and the destruction of Asia-Pacific tropical forests. Nature 629, 370–375 (2024). https://doi.org/10.1038/s41586-024-07303-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-024-07303-5

  • Springer Nature Limited

Search

Navigation