Abstract

The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.30 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.66 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.

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Change history

  • Updated online 09 September 2015

    Minor changes were made to the Author Contributions statements.

  • Updated online 13 April 2016

    The link for the global tree density map was added to the Author Information section.

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Acknowledgements

We thank P. Peterkins for her support throughout the study. We also thank Plant for the Planet for initial discussions and for collaboration during the study. The main project was funded by grants to T.W.C. from the Yale Climate and Energy Institute and the British Ecological Society. We acknowledge various sources for tree density measurements and estimates: the Canadian National Forest Inventory (https://nfi.nfis.org/index.php), the US Department of Agriculture Forest Service for their National Forest Inventory and Analysis (http://fia.fs.fed.us/), the Taiwan Forestry Bureau (which provided the National Vegetation Database of Taiwan), the DFG (German Research Foundation), BMBF (Federal Ministry of Education and Science of Germany), the Floristic and Forest Inventory of Santa Catarina (IFFSC), the National Vegetation Database of South Africa, and the Chilean research grants FONDECYT no. 1151495. For Europe NFI plot data were brought together with input from J. Rondeux and M. Waterinckx, Belgium, T. Bélouard, France, H. Polley, Germany, W. Daamen and H. Schoonderwoerd, Netherlands, S. Tomter, Norway, J. Villanueva and A. Trasobares, Spain, G. Kempe, Sweden. New Zealand Natural Forest plot data were collected by the LUCAS programme for the Ministry for the Environment (New Zealand) and sourced from the National Vegetation Survey Databank (New Zealand) (http://nvs.landcareresearch.co.nz). We also acknowledge the BCI forest dynamics research project, which was funded by National Science Foundation grants to S. P. Hubbell, support from the Center for Tropical Forest Science, the Smithsonian Tropical Research Institute, the John D. and Catherine T. MacArthur Foundation, the Mellon Foundation, the Small World Institute Fund, numerous private individuals, the Ucross High Plains Stewardship Initiative, and the hard work of hundreds of people from 51 countries over the past two decades. The plot project is part of the Center for Tropical Forest Science, a global network of large-scale demographic tree plots.

Author information

Affiliations

  1. Yale School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut 06511, USA

    • T. W. Crowther
    • , H. B. Glick
    • , K. R. Covey
    • , C. Bettigole
    • , D. S. Maynard
    • , J. R. Smith
    • , G. Hintler
    • , M. C. Duguid
    • , W. Jetz
    • , P. M. Umunay
    • , C. W. Rowe
    • , M. S. Ashton
    • , P. R. Crane
    •  & M. A. Bradford
  2. Department of Environmental Sciences, University of Helsinki, Helsinki 00014, Finland

    • S. M. Thomas
  3. Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06511, USA

    • G. Amatulli
    • , M.-N. Tuanmu
    •  & W. Jetz
  4. Department of Life Sciences, Silwood Park, Imperial College, London SL5 7PY, UK

    • W. Jetz
  5. Departamento de Ciencias Forestales, Universidad de La Frontera, Temuco 4811230, Chile

    • C. Salas
  6. RedCastle Resources, Salt Lake City, Utah 84103, USA

    • C. Stam
  7. Universidade Federal do Sul da Bahia, Ferradas, Itabuna 45613-204, Brazil

    • D. Piotto
  8. Forestry Department, Food and Agriculture Organization of the United Nations, Rome 00153, Italy

    • R. Tavani
  9. Operation Wallacea, Spilbsy, Lincolnshire PE23 4EX, UK

    • S. Green
    •  & G. Bruce
  10. Durrell Institute of Conservation and Ecology (DICE), School of Anthropology and Conservation (SAC), University of Kent, Canterbury ME4 4AG, UK

    • S. Green
  11. Molecular Imaging Research Center MIRCen/CEA, CNRS URA 2210, 91401 Orsay Cedex, France

    • S. J. Williams
  12. Landcare Research, Lincoln 7640, New Zealand

    • S. K. Wiser
  13. WSL, Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf, Switzerland

    • M. O. Huber
  14. Environmental Science Group, Wageningen University & Research Centre, 6708 PB, The Netherlands

    • G. M. Hengeveld
    •  & G.-J. Nabuurs
  15. Center for Forest Ecology and Productivity RAS, Moscow 117997, Russia

    • E. Tikhonova
  16. CEN Center for Earth System Research and Sustainability, Institute of Geography, University of Hamburg, Hamburg 20146, Germany

    • P. Borchardt
  17. Department of Botany and Zoology, Masaryk University, Brno 61137, Czech Republic

    • C.-F. Li
  18. South African National Biodiversity Institute, Kirstenbosch Research Centre, Claremont 7735, South Africa

    • L. W. Powrie
  19. Institute of Plant Sciences, Botanical Garden, and Oeschger Centre for Climate Change Research, University of Bern, 3013 Bern, Switzerland

    • M. Fischer
  20. Senckenberg Gesellschaft für Naturforschung, Biodiversity and Climate Research Centre (BIK-F), 60325 Frankfurt, Germany

    • M. Fischer
  21. Department of Plant Systematics, University of Bayreuth, 95447 Bayreuth, Germany

    • A. Hemp
  22. Albrecht von Haller Institute of Plant Sciences, Georg August University of Göttingen, 37073 Göttingen, Germany

    • J. Homeier
  23. Tropical Ecology Research Group, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK

    • P. Cho
  24. Universidade Regional de Blumenau, Departamento de Engenharia Florestal, Blumenau/Santa Catarina 89030-000, Brazil

    • A. C. Vibrans
  25. Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China

    • S. L. Piao

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Contributions

The study was conceived by T.W.C and G.H. and designed by T.W.C., K.R.C. and M.A.B. Statistical analyses were conducted by H.B.G., S.M.T., J.R.S., C.B., D.S.M. and T.W.C. and mapping was conducted by H.B.G. and C.B. The manuscript was written by T.W.C. with input from M.A.B., P.C., D.S.M., H.B.G. and C.B., with comments provided by all other authors. Tree density measurements or geospatial data from all over the world were contributed by K.R.C., S.M.T., M.C.D., G.A., M.N.T., W.J., C.Sa., C.St., D.P., T.T., S.G., G.B., S.J.W., S.K.W., M.O.H., G.M.H., G.J.N., E.T., P.B., C.F.L., L.W.P.,M.F., A.H., J.H., P.C., A.C.V., P.M.U., S.L.P., C.W.R. and M.S.A.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to T. W. Crowther.

The global tree density map can be found at http://elischolar.library.yale.edu/yale_fes_data/1/.

Extended data

Supplementary information

Excel files

  1. 1.

    Supplementary Table 1

    Summary Table showing the number of plot estimates and total tree numbers (with 95% confidence interval) at the biome and global scale.

  2. 2.

    Supplementary Table 2

    This table shows the number of trees and tree densities for countries of the world, as estimated using 2 independent approaches (biome and ecoregion-level models) and the database of Global Administrative Areas, version 2.7 (http://gadm.org/).