Preprints
https://doi.org/10.5194/essd-2026-226
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/essd-2026-226
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
22 May 2026
| 22 May 2026
Status: this preprint is currently under review for the journal ESSD.
The global forest diameter spectrum using a machine learning approach
Abstract. Global forest assessments assist climate policy development, ecosystem science, and conservation planning, yet they rely on biomass and canopy data that do not explicitly represent the stand structural attributes derived from tree diameter measurements. This limits the ability to compare size-related structure and within-stand heterogeneity at large spatial scales. Here we present a global, spatially explicit dataset of stand-level tree diameter structure for forest cover in 2020 at 0.027° (~3 km) resolution, based on 1,203,524 georeferenced forest inventory plots comprising 54.6 million trees (≥10 cm DBH) integrated with more than 50 environmental and satellite-derived covariates into machine learning models. The dataset provides the first globally consistent maps of three complementary diameter-based metrics: arithmetic mean diameter (Dmean), quadratic mean diameter (Dqm), and the coefficient of variation of diameter (Dcv), representing average tree size, large-tree dominance, and within-stand size variability, respectively. Model performance of the ecozone-specific Random Forest framework ranged from R² = 0.41–0.82 (RMSE = 3.91–4.63 cm) for Dmean, R² = 0.43–0.83 (RMSE = 4.38–5.27 cm) for Dqm, and R² = 0.47–0.62 with (RMSE = 0.10–0.13) for Dcv across different forest ecozones. By jointly quantifying central tendency and variability in tree size, the dataset revealed spatial patterns of forest structural organization not captured by existing biomass or canopy-height products. It provides a consistent baseline for cross-biome comparison of forest structure, supporting parameterization and evaluation of vegetation and Earth system models, while offering an independent benchmark for remotely sensed structural proxies. Furthermore, it enables spatial assessment of stand structural attributes, including large-tree dominance and structural complexity, facilitating integration of diameter-based structure into global analyses of carbon dynamics and ecosystem functioning.
How to cite. Mitra, A., Harris, N., Gamarra, J. G. P., Bastian, M. L., Crowther, T. W., Picard, N., Herold, M., Hui, C., de-Miguel, S., Powell, W. G., Beane, N. R., Shallock, J. R., van der Plas, F., Lawes, M. J., Zhou, M., Jahanshahi, M., Tchebakova, N. M., Parfenova, E. I., Reich, P., Alvarez, C. I., Griffith, D. M., Phillips, O. L., Mirabel, A., Sandker, M., Choi, W., Abbasi, A. O., Alberti, G., Altman, J., Alves, L. F., Amani, B. H. K., Amani, C., Ammer, C., Avitabile, V., Aymard C., G. A., Azihou, A. F., Baker, T. R., Balazy, R., Barroso, J. G., Bastin, J.-F., Bauters, M., Bayat, M., Beeckman, H., van den Berg, E., Bhat, J. A., Bhatt, A., Bhely, A. I., Birigazzi, L., Birnbaum, P., Bitariho, R., Boeckx, P., Bogaert, J., Bondarev, A., Bongers, F., Bouchard, E., Bourland, N., Brancalion, P. H. S., Brearley, F. Q., Bufford, J. L., Corral-Rivas, J. J., Briseno-Reyes, J., Broadbent, E. N., Burslem, D. F. R. P., de Camargo, P. B., Češljar, G. D., Chaturvedi, R. K., Chen, H. Y. H., Chen, J., Chianucci, F., Chuyong, G., Cienciala, E., Restrepo Correa, Z., Lola da Costa, A., Cuchietti, A., Dar, J. A., Dayanandan, S., Decuyper, M., Do, T. V., Dolezal, J., Đorđević, I., Drake, D. R., Durigan, G., Elogne, G.-M. A., Enoki, T., Espejo, J. S., Fayle, T. M., Ferreira, R. L. C., Foster, P. F., Frizzera, L., Gaoue, O. G., Cazzolla Gatti, R., Gianelle, D., Guevara, M., Aguirre Gutiérrez, J., Habonayo, R., Harris, D. J., Hau, B. C. H., Hérault, B., Hubau, W., Imai, N., Jagodzinski, A. M., Janeček, Š., Jansen, P. A., Jaroszewicz, B., Johannsen, V. K., Joly, C. A., Johnson, D. J., Jucker, T., Marimon Junior, B. H., Cosme de Oliveira Junior, R., Kahsay, G. A., Karminov, V., Kearsley, E., Kennard, D. K., Kepfer-Rojas, S., Keppel, G., Khan, M. L., Kigomo, J. N., Kim, H. S., Kim, S., Klauberg, C., Korjus, H., Kothandaraman, S., Kraxner, F., Krivobokov, L., Kumar, A., Kumar, G., Kvashnina, A. E., Laarmann, D., Laurent, F., Laurin, G. V., Leite, R. V., Lerink, B., Lewis, S. L., Libalah, M. B., Liu, W., Lovett, J., Lu, H., Soriano-Luna, M. D. L. A., Lykke, A. M., Mackintosh, E. J., Makana, J.-R., Marshall, A. R., Martin, E. H., Matula, R., Mbuvi, M., Medina, S. L., Medjibe, V. P., Mensah, D., Mensah, S., Metzker, T., Miścicki, S., Mukhortova, L., Mukul, S. A., Murdjoko, A., Nabuurs, G.-J., N'Guessan, A. E., Ngugi, M. R., Ngute, A. S. K., Nord-Larsen, T., Ochuodho, T. O., Ogana, F. N., Arroyo Padilla, L., Pala, N. A., Paquette, A., Peri, P. L., Pfautsch, S., Piedade, M. T. F., Piotto, D., Pipoly III, J. J., Pitman, N. C. A., Poulsen, J. R., Raghubanshi, A., Rana, D., Rodeghiero, M., Rolim, S., Saikia, P., Schall, P., Schepaschenko, D., Schöngart, J., Šebeň, V., Sellan, G., Silva, C. A., Silveira, M., Singh, J., Slik, F., Socha, J., Soto, J. D., Souza, A. F., Srivastava, P. K., ter Steege, H., Stereńczak, K., Sundarapandian, S., Svátek, M., Svenning, J.-C., Tang, X., Thomas, R. S., Tomao, A., Trethowan, L. A., Tropek, R., Upadhyaya, K., Valencia, R., Vásquez, R., Vega-Nieva, D. J., Verbeeck, H., Viana, H. F., Vibrans, A. C., Vieira, S. A., Vinceti, B., Vleminckx, J., Vos, V. A., Vozmishcheva, A. S., Vozmitel, F., Wagia, H., Wang, H.-F., Wasingya, E. K., Webb, E. L., Wekesa, C., Wortel, V., Yakusu, E. K., Yu, Z., Zambrano, A. M. A., Zo-Bi, I. C., and Liang, J.: The global forest diameter spectrum using a machine learning approach, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2026-226, in review, 2026.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Earth System Science Data.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.Download & links
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Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
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RC1: 'Comment on essd-2026-226', Jonas Lembrechts, 27 Jun 2026
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AC1: 'Reply on RC1', Ankita Mitra, 26 Jul 2026
We sincerely thank the reviewer for the positive evaluation of our work and for the thoughtful, constructive comments and suggestions regarding data quality, model robustness, and validation. We greatly appreciate the time and effort devoted to reviewing our manuscript, and the feedback has helped us improve its clarity, rigor, and overall quality. Detailed point-by-point responses are provided in the accompanying file, "Comments_Responseletter_R1.pdf." In this document, each comment is addressed individually, with the reviewer's comments shown in black, our responses shown in green, and the corresponding revisions to the manuscript also highlighted in green to facilitate clarity and ease of review.
Regards.
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AC1: 'Reply on RC1', Ankita Mitra, 26 Jul 2026
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RC2: 'Comment on essd-2026-226', Anonymous Referee #2, 06 Oct 2026
This data paper develops three global forest diameter products by combining forest inventory data with several geospatially explicit layers representing vegetation characteristics, topography, soils, climate, etc., using a machine learning approach. The products also provide spatially explicit uncertainty estimates. The manuscript is well written and concise, and the methodology is straightforward to follow. I expect the resulting datasets to be useful to a broad community.
I have two thoughts that the authors may wish to consider:
1. Training models by ecozone versus ecozone × continent
My understanding is that the machine learning models are trained separately for each ecozone. These ecozones can span multiple continents. For example, boreal forests occur across both North America and Eurasia. However, forest composition can differ substantially among continents within the same ecozone. For example, spruce may be more dominant in parts of North America, whereas pine and larch may be more important in Eurasia. These differences in species composition could translate into substantial differences in forest structural characteristics, including diameter distributions, as well as differences in the environmental variables that best predict them.
The same issue may potentially apply to temperate and tropical forests. I therefore wonder whether training separate models for each ecozone–continent combination could improve predictive performance compared with the current approach. Is this something the authors considered? If so, could the authors briefly discuss what they found? If not, do the authors think that this would be a potentially useful sensitivity analysis?
2. Number and importance of predictor variables
I understand that, for an ESSD paper, the primary emphasis is on producing spatially explicit datasets rather than on explaining the mechanisms underlying spatial patterns. Nevertheless, I wonder whether the authors could provide some additional information on the number and importance of the predictor variables.
In particular, how does model performance change as the number of predictors is reduced? For example, do the best 10 or 20 predictors achieve performance close to that obtained using the full set of 50+ predictors? Conversely, is there a point at which adding additional predictors provides little further improvement in predictive performance? It would also be interesting to know whether this relationship varies spatially or among ecozones.
Relatedly, which predictor variables are most influential, and how does their importance vary spatially? I appreciate that correlated predictors can make variable-importance measures difficult to interpret, but even a broad assessment of predictor importance could provide useful context for interpreting the resulting products, particularly when considered alongside the uncertainty layers.
Finally, retaining only the most influential predictors could potentially reduce computational costs and make the models easier to interpret. Could the authors comment on how they considered the trade-off between model performance, computational complexity, and interpretability when selecting the predictor set?
Citation: https://doi.org/10.5194/essd-2026-226-RC2
Data sets
Rasters- Global prediction of tree diameter across forest cover Ankita Mitra https://figshare.com/s/689e4be80a63d05d5189
CSV-Grid predictions of forest diameter structure Ankita Mitra https://figshare.com/s/91c6cc4f2b9757d92da8
Metadata associated with the study Ankita Mitra https://figshare.com/s/34c21c03883a01ef708f
Global dataset used to train the models for tree diameter study Ankita Mitra https://figshare.com/s/c795146ea9e8aa42f81f
Model code and software
RF models for the tree diameter study Ankita Mitra https://figshare.com/s/60eac94e4c64a95c6d13
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Ankita Mitra
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
Nancy Harris
Global Forest Watch, World Resources Institute, Washington, DC, USA
Javier G. P. Gamarra
Forestry Division, Food and Agriculture Organization of the United Nations, Rome, Italy
Meredith L. Bastian
Proceedings of the National Academy of Sciences, Washington, DC, USA
Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
Thomas W. Crowther
King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
BRANCH Institute, Zug, Switzerland
Nicolas Picard
GIP Ecofor, Paris, France
Martin Herold
GFZ Helmholtz Centre for Geosciences, Telegrafenberg, Potsdam, Brandenburg 14473, Germany
Department of Mathematical Sciences, Stellenbosch, South Africa
African Institute for Mathematical Sciences, Cape Town, South Africa
National Institute for Theoretical and Computational Sciences, Stellenbosch, South Africa
Sergio de-Miguel
Department of Agricultural and Forest Sciences and Engineering, University of Lleida, 25198 Lleida, Spain
Forest Science and Technology Centre of Catalonia (CTFC), 25280 Solsona, Spain
W. Gabe Powell
U.S. Army Engineer Research and Development Center (ERDC), Environmental Laboratory, Forest Ecosystem Dynamics Team, USA
Nathan R. Beane
U.S. Army Engineer Research and Development Center (ERDC), Environmental Laboratory, Forest Ecosystem Dynamics Team, USA
John R. Shallock
U.S. Army Engineer Research and Development Center (ERDC), Environmental Laboratory, Forest Ecosystem Dynamics Team, USA
Fons van der Plas
Plant Ecology and Nature Conservation, Wageningen University & Research, Wageningen, The Netherlands
Michael J. Lawes
School of Life Sciences, University of KwaZulu-Natal, Scottsville 3209, South Africa
Institute of Biodiversity and Environmental Conservation (IBEC), Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
Mo Zhou
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
Mohammad Jahanshahi
Department of Civil and Construction Engineering, Purdue University, West Lafayette, IN, USA
Nadezhda M. Tchebakova
Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences, Federal Research Center “Krasnoyarsk Science Center”, Krasnoyarsk, Russia
Elena I. Parfenova
Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences, Federal Research Center “Krasnoyarsk Science Center”, Krasnoyarsk, Russia
Peter Reich
Institute for Global Change Biology, and School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA
Department of Forest Resources, University of Minnesota, St. Paul, MN, USA
Cesar Ivan Alvarez
Centre for Climate Resilience, University of Augsburg, Universitätsstrasse 12a, 86159 Augsburg, Germany
Daniel M. Griffith
Laboratorio de Ecología Tropical y Servicios Ecosistémicos (EcoSs Lab), Departamento de Ciencias Biológicas y Agropecuarias, Universidad Técnica Particular de Loja, Loja, Ecuador
Oliver L. Phillips
School of Geography, University of Leeds, Leeds, UK
Ariane Mirabel
Cirad, UPR Forêts et Sociétés, University of Montpellier, Montpellier, France
Cirad, UMR EcoFoG (AgroParistech, CNRS, INRAE, Université des Antilles, Université de la Guyane), Campus Agronomique, Kourou, French Guiana
University of Brasilia, Department of Forestry, Brasília, Brazil
Marieke Sandker
Forestry Division, Food and Agriculture Organization of the United Nations, Rome, Italy
WookJin Choi
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
Akane O. Abbasi
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
Giorgio Alberti
Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
National Biodiversity Future Centre (NBFC), University of Palermo, Palermo, Italy
Jan Altman
Institute of Botany of the Czech Academy of Sciences, Dukelská 135, 379 01 Třeboň, Czech Republic
Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague 6–Suchdol, Czech Republic
Luciana F. Alves
Center for Tropical Research, Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
Bienvenu H. K. Amani
Université Nangui Abrogoua, Unité de Formation et de Recherche en Sciences de la Nature, 02 BP 801 Abidjan 02, Laboratoire d’Écologie et du Développement Durable (LEDD), Abidjan, Côte d’Ivoire
Christian Amani
Université Officielle de Bukavu, Bukavu, Democratic Republic of Congo
Christian Ammer
Silviculture and Forest Ecology of the Temperate Zones, University of Göttingen, Göttingen, Germany
Valerio Avitabile
Independent researcher, Ispra, Italy
Gerardo A. Aymard C.
UNELLEZ-Guanare, Programa de Ciencias del Agro y el Mar, Herbario Universitario (PORT), Mesa de Cavacas, estado Portuguesa 3350, Venezuela
Jardín Botánico de Bogotá José Celestino Mutis, Cl. 63 #68-95, Bogotá DC, Colombia
Akomian F. Azihou
Laboratory of Applied Ecology, Faculty of Agricultural Sciences, University of Abomey-Calavi, 01 BP 526, Cotonou, Benin
Timothy R. Baker
School of Geography, University of Leeds, Leeds, UK
Radomir Balazy
Forest Research Institute, Braci Leśnej 3, Sękocin Stary, 05-090, Poland
Jorcely G. Barroso
Universidade Federal do Acre, Campus de Cruzeiro do Sul, Acre, Brazil
Jean-François Bastin
TERRA Teaching and Research Centre, Gembloux Agro Bio-Tech, Université de Liège, Gembloux, Belgium
Marijn Bauters
Q-ForestLab, Department of Environment, Ghent University, Ghent, Belgium
Mahmoud Bayat
Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
Hans Beeckman
Service of Wood Biology, Royal Museum for Central Africa, Tervuren, Belgium
Eduardo van den Berg
Universidade Federal de Lavras, Departamento de Ecologia e Conservação, Lavras, Brazil
Jahangeer A. Bhat
Piramal School of Educational Leadership, India
Anupam Bhatt
CSIR–Institute of Himalayan Bioresource Technology, Palampur (H.P.) 176061, India
Angoboy Ilondea Bhely
Institut National pour l’Etude et la Recherche Agronomiques, Kinshasa, Democratic Republic of Congo
Luca Birigazzi
Forestry expert, Via Unione Sovietica 105, Grosseto, Italy
Philippe Birnbaum
CIRAD, UMR AMAP, F-34398 Montpellier, France
AMAP, Univ Montpellier, CIRAD, CNRS, INRAE, IRD, Montpellier, France
Robert Bitariho
Institute of Tropical Forest Conservation, Mbarara University of Science and Technology, Mbarara, Uganda
Pascal Boeckx
Isotope Bioscience Laboratory (ISOFYS), Department of Green Chemistry and Technology, Ghent University, Gent, Belgium
Jan Bogaert
TERRA Teaching and Research Centre, Gembloux Agro Bio-Tech, Université de Liège, Gembloux, Belgium
Alexander Bondarev
Siberian Federal University, Krasnoyarsk, Russia
Frans Bongers
Forest Ecology and Forest Management Group, Wageningen University & Research, Wageningen, The Netherlands
Elise Bouchard
Centre for forest research, Département des sciences biologiques, Université du Québec à Montréal, Montreal, Canada
Nils Bourland
Service of Wood Biology, Royal Museum for Central Africa, Tervuren, Belgium
Climate Risk Assessment Center, Brussels, Belgium
Pedro H. S. Brancalion
Department of Forest Sciences, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Piracicaba, Brazil
Center for Carbon Research in Tropical Agriculture, University of São Paulo, Piracicaba, Brazil
Re.green, Rio de Janeiro, Brazil
Francis Q. Brearley
Department of Natural Sciences, Manchester Metropolitan University, Manchester, UK
Jennifer L. Bufford
Bioeconomy Science Institute, Lincoln, New Zealand
José Javier Corral-Rivas
Facultad de Ciencias Forestales y Ambientales, Universidad Juárez del Estado de Durango, México
Jaime Briseno-Reyes
Facultad de Ciencias Forestales y Ambientales, Universidad Juárez del Estado de Durango, México
Eben North Broadbent
School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL 32611, USA
David F. R. P. Burslem
School of Biological Sciences and Interdisciplinary Institute, University of Aberdeen, Aberdeen, UK
Plinio Barbosa de Camargo
Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, SP, Brazil
Goran D. Češljar
Department of Spatial regulation, Institute of Forestry, GIS and Forest Policy, Belgrade, Serbia
Ravi K. Chaturvedi
Center for Integrative Conservation & Yunnan Key Laboratory for Conservation of Tropical Rainforests & Asian Elephant, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, P.R. China
Han Y. H. Chen
Faculty of Natural Resources Management, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada
Ontario Forest Research Institute, Ministry of Natural Resources, Sault Ste. Marie, Ontario, Canada
Jiaxin Chen
Ontario Forest Research Institute, Ministry of Natural Resources, Sault Ste. Marie, Ontario, Canada
Francesco Chianucci
CREA – Research Centre for Forestry and Wood, Arezzo, Italy
George Chuyong
Department of Botany and Plant Physiology, University of Buea, Buea, Cameroon
Emil Cienciala
IFER – Institute of Forest Ecosystem Research, Jílové u Prahy, Czech Republic
Global Change Research Institute CAS, Brno, Czech Republic
Zorayda Restrepo Correa
Grupo de Servicios Ecosistémicos y Cambio Climático, Corporación COL-TREE, Medellín, Colombia
Antonio Lola da Costa
Universidade Federal do Pará, Instituto de Geociências, Rua Augusto Correa, 01, CEP 66075-110, Belém, Pará, Brasil
Anibal Cuchietti
Forestry Division, Food and Agriculture Organization of the United Nations, Rome, Italy
Javid Ahmad Dar
Terrestrial Ecology and Modelling (TEaM) Lab, Department of Environmental Science and Engineering, SRM University-AP, Amaravati, India
Centre for Geospatial Technology, SRM University-AP, Amaravati, India
Selvadurai Dayanandan
Biology Department, Concordia University, Montreal, Quebec, Canada
Mathieu Decuyper
Wageningen Environmental Research, Wageningen University & Research, Wageningen, Netherlands
Tran Van Do
Silviculture Research Institute, Vietnamese Academy of Forest Sciences, Hanoi, Vietnam
Jiri Dolezal
Institute of Botany of the Czech Academy of Sciences, Dukelská 135, 379 01 Třeboň, Czech Republic
Faculty of Science, University of South Bohemia, Branišovská 1760, CZ-370 05 České Budějovice, Czech Republic
Ilija Đorđević
Institute of Forestry, Belgrade, Serbia
Donald R. Drake
Harold L. Lyon Arboretum, University of Hawaiʻi at Mānoa, Honolulu, HI, USA
Giselda Durigan
Instituto de Pesquisas Ambientais, São Paulo, Brazil
Universidade Estadual de Campinas, Campinas, Brazil
Guy-Michel A. Elogne
Institut National Polytechnique Félix Houphouët-Boigny (INPHB), Yamoussoukro, Côte d’Ivoire
Tsutomu Enoki
Ashoro Research Forest, Kyushu University, 1-85 Kita 5, Ashoro, Hokkaido 089-3705, Japan
Javier Silva Espejo
Departamento de Biologia, Universidad de La Serena, Chile
Instituto de Ecologia y Biodiversidad, La Serena, Chile
Tom Maurice Fayle
School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
Biology Centre of the Czech Academy of Sciences, Institute of Entomology, České Budějovice, Czech Republic
Rinaldo Luiz Caraciolo Ferreira
Federal Rural University of Pernambuco, Department of Forest Science, Avenida Dom Manoel de Medeiros, s/n, Dois Irmãos, Recife, PE, Brazil
Paul F. Foster
Bijagual Ecological Reserve, Sarapiquí, Costa Rica
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
Lorenzo Frizzera
Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38098 San Michele all’Adige (TN), Italy
Orou G. Gaoue
Department of Ecology and Evolutionary Biology, University of Tennessee Knoxville, Knoxville, TN 37996, USA
Laboratoire d’Etude sur la Dynamique des Populations (PopDYN), Faculté d’Agronomie, Université de Parakou, Parakou, Benin
African Centre for DNA Barcoding, Department of Botany and Plant Biotechnology, University of Johannesburg, APK Campus, Johannesburg, South Africa
Roberto Cazzolla Gatti
Department of Biological, Geological, and Environmental Sciences (BiGeA), Alma Mater Studiorum, University of Bologna, Bologna, Italy
Damiano Gianelle
Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38098 San Michele all’Adige (TN), Italy
Mario Guevara
Instituto de Geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Qro., Mexico
Jesús Aguirre Gutiérrez
Georgina Mace Centre for the Living Planet, Imperial College London, Ascot, UK
Facultad de Ciencias Forestales y Ambientales, Universidad Juárez del Estado de Durango, México
Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, UK
Leverhulme Centre for Nature Recovery, University of Oxford, Oxford, UK
Richard Habonayo
Université du Burundi, Faculté d’Agronomie et de Bio-Ingénierie, Centre de Recherche en Sciences des Productions Animales, Végétales et Environnementales (CRAVE), B.P. 2940 Bujumbura, Burundi
David J. Harris
Royal Botanic Garden Edinburgh, Edinburgh, UK
Billy C. H. Hau
School of Biological Sciences, The University of Hong Kong, Hong Kong, China
Bruno Hérault
CIRAD, Forêts et Sociétés, F-34398 Montpellier, France
Forêts et Sociétés, Univ Montpellier, CIRAD, Montpellier, France
Wannes Hubau
Ghent University, Faculty of Bioscience Engineering, Laboratory of Wood Technology, Ghent, Belgium
Service of Wood Biology, Royal Museum for Central Africa, Tervuren, Belgium
Nobuo Imai
Tokyo University of Agriculture, Tokyo, Japan
Andrzej M. Jagodzinski
Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland
Poznań University of Life Sciences, Department of Game Management and Forest Protection, Wojska Polskiego 71D, 60-625 Poznań, Poland
Štěpán Janeček
Department of Ecology, Faculty of Science, Charles University, Prague, Czechia
Patrick A. Jansen
Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands
Department of Biology, Utrecht University, Utrecht, The Netherlands
Bogdan Jaroszewicz
University of Warsaw, Faculty of Biology, Białowieża Geobotanical Station, Białowieża, Poland
Vivian Kvist Johannsen
University of Copenhagen, Department of Geosciences and Natural Resource Management, Copenhagen, Denmark
Carlos A. Joly
Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil, 13083-862, Brazil
Daniel J. Johnson
School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL 32611, USA
Tommaso Jucker
School of Biological Sciences, University of Bristol, Bristol, UK
Ben Hur Marimon Junior
State University of Mato Grosso (UNEMAT), Plant Ecology Laboratory (LABEV), Graduate Program in Ecology and Conservation, Nova Xavantina, Mato Grosso, Brazil
Raimundo Cosme de Oliveira Junior
Embrapa Amazônia Oriental, Santarém, Pará, Brazil
Goytom A. Kahsay
University of Copenhagen, Department of Geosciences and Natural Resource Management, Copenhagen, Denmark
Victor Karminov
Bauman Moscow State Technical University (BMSTU), Moscow, Russia
Elizabeth Kearsley
Q-ForestLab, Department of Environment, Ghent University, Ghent, Belgium
Deborah K. Kennard
Colorado Mesa University, Grand Junction, USA
Sebastian Kepfer-Rojas
Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
Gunnar Keppel
School of Biological Sciences and Environment Institute, The University of Adelaide, Adelaide, SA 5005, Australia
Mohammed Latif Khan
Department of Botany, Dr. Harisingh Gour Vishwavidyalaya (A Central University), Sagar 470003, Madhya Pradesh, India
John N. Kigomo
Kenya Forestry Research Institute, P.O. Box 20412-00200, Nairobi, Kenya
Hyun Seok Kim
Department of Agriculture, Forestry and Bioresources, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea
Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea
Interdisciplinary Program in Agricultural and Forest Meteorology, Seoul National University, Seoul 08826, Republic of Korea
Sukyung Kim
Department of Agriculture, Forestry and Bioresources, College of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
Agriculture and Life Sciences Research Institute, Kangwon National University, Chuncheon, Republic of Korea
Carine Klauberg
School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL 32611, USA
Henn Korjus
Estonian University of Life Sciences, Institute of Forestry and Engineering, Tartu, Estonia
Subashree Kothandaraman
Terrestrial Ecology and Modelling (TEaM) Lab, Department of Environmental Science and Engineering, SRM University-AP, Amaravati, India
Centre for Geospatial Technology, SRM University-AP, Amaravati, India
Florian Kraxner
International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
Leonid Krivobokov
Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences, Federal Research Center “Krasnoyarsk Science Center”, Krasnoyarsk, Russia
Amit Kumar
Department of Geography, Institute of Science, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India
Gajendra Kumar
Wildlife Institute of India, Dehradun, India
Anna E. Kvashnina
Denezhkin Kamen Russian Federal Nature Preserve (Zapovednik), Russia
Diana Laarmann
Estonian University of Life Sciences, Estonia
Felix Laurent
Service of Wood Biology, Royal Museum for Central Africa, Tervuren, Belgium
Ghent University, Faculty of Bioscience Engineering, Laboratory of Wood Technology, Ghent, Belgium
Gaia Vaglio Laurin
National Research Council (CNR), Research Institute on Terrestrial Ecosystem (IRET), Montelibretti Research Area, Italy
Rodrigo Vieira Leite
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
Bas Lerink
Wageningen Environmental Research, Wageningen University & Research, Wageningen, Netherlands
Simon L. Lewis
School of Geography, University of Leeds, Leeds, UK
Department of Geography, University College London, London, UK
Moses B. Libalah
Department of Plant Biology, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
Plant Systematics and Ecology Laboratory, Higher Teachers’ Training College, University of Yaoundé, Yaoundé, Cameroon
Weiguo Liu
College of Forestry, Northwest Agriculture & Forestry University, Yangling, China
Qinling National Forest Ecosystem Research Station, Yangling, Shaanxi 712100, China
Jon Lovett
School of Geography, University of Leeds, Leeds, UK
Huicui Lu
Faculty of Forestry, Qingdao Agricultural University, Qingdao 266109, China
Maria de los Angeles Soriano-Luna
Comisión Nacional Forestal (CONAFOR), Zapopan, Jalisco, México
Anne Mette Lykke
Department of Ecoscience, Aarhus University, Denmark
Emma Jane Mackintosh
Forest Research Institute, University of the Sunshine Coast, Queensland, Australia
Jean-Remy Makana
Institut National pour l’Etude et la Recherche Agronomiques, Kinshasa, Democratic Republic of Congo
Andrew R. Marshall
Forest Research Institute, University of the Sunshine Coast, Queensland, Australia
Reforest Africa, Mang’ula, Tanzania
Flamingo Land Ltd., Kirby Misperton, UK
Emanuel H. Martin
College of African Wildlife Management, Mweka, Moshi, Tanzania
Radim Matula
Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague 6–Suchdol, Czech Republic
Musingo Mbuvi
Kenya Forestry Research Institute, P.O. Box 20412-00200, Nairobi, Kenya
Sandra Liliana Medina
Comisión Nacional Forestal (CONAFOR), Zapopan, Jalisco, México
Vincent P. Medjibe
The Nature Conservancy (TNC-Gabon), Gabon
Desmond Mensah
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
Sylvanus Mensah
Chair of Forest Growth and Dendroecology, Albert-Ludwigs-Universität Freiburg, Germany
Laboratoire de Biomathématiques et d'Estimations Forestières, Université d'Abomey-Calavi, Bénin
Thiago Metzker
IBAM – Instituto Bem Ambiental, Belo Horizonte, Grupo Myr – ESG Solutions, Brazil
Stanisław Miścicki
Warsaw University of Life Sciences, Warsaw, Poland
Liudmila Mukhortova
Sukachev Institute of Forest, Siberian Branch of the Russian Academy of Sciences, Federal Research Center “Krasnoyarsk Science Center SB RAS”, Krasnoyarsk, Russia
Sharif A. Mukul
Department of Environment and Development Studies, United International University, Dhaka 1212, Bangladesh
Tropical Forests and People Research Centre, University of the Sunshine Coast, Maroochydore DC, Queensland 4556, Australia
Department of Earth and Environment, Florida International University, Miami, FL, USA
Agustinus Murdjoko
Fakultas Kehutanan, Universitas Papua, Jalan Gunung Salju Amban, Manokwari, Papua Barat, Indonesia
Gert-Jan Nabuurs
Wageningen Environmental Research, Wageningen University & Research, Wageningen, Netherlands
Anny Estelle N'Guessan
UFR Biosciences, Félix Houphouët-Boigny University, Abidjan, Côte d'Ivoire
Michael R. Ngugi
Queensland Herbarium and Biodiversity Science, Department of the Environment, Tourism, Science and Innovation (DETSI), Brisbane Botanic Gardens, Mt Coot-tha Road, Toowong, Qld 4066, Australia
Alain Senghor K. Ngute
Forest Research Institute, University of the Sunshine Coast, Queensland, Australia
Australian Wildlife Conservancy, Perth, Western Australia, Australia
Thomas Nord-Larsen
Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
Thomas O. Ochuodho
Department of Forestry and Natural Resources, University of Kentucky, Lexington, KY, USA
Friday N. Ogana
Virginia Polytechnic Institute and State University, Department of Forest Resources and Environmental Conservation, 310 West Campus Dr., Blacksburg, VA 24061, USA
Luzmila Arroyo Padilla
Museo de Historia Natural Noel Kempff Mercado; Universidad Autónoma Gabriel René Moreno, Bolivia
Nazir A. Pala
Faculty of Forestry, SKUAST-Kashmir, Jammu & Kashmir, India
Alain Paquette
Centre for forest research, Département des sciences biologiques, Université du Québec à Montréal, Montreal, Canada
Pablo L. Peri
Instituto Nacional de Tecnología Agropecuaria (INTA), Río Gallegos, Santa Cruz, Argentina
Universidad Nacional de la Patagonia Austral (UNPA)-CONICET, Río Gallegos, Santa Cruz, Argentina
Sebastian Pfautsch
Urban Transformations Research Centre, Western Sydney University, 6 Hassall Street, Parramatta, NSW 2150, Australia
Maria Teresa F. Piedade
National Institute for Amazon Research (INPA), Coordination of Environmental Dynamics (CODAM), Ecology, Monitoring, and Sustainable Use of Wetlands Group (MAUA), Manaus, Brazil
Daniel Piotto
Centro de Formação em Ciências Agroflorestais, Universidade Federal do Sul da Bahia, BR 415, km 29, Ilhéus-BA, 45613-204, Brazil
John James Pipoly III
Florida Atlantic University, Boca Raton, Florida, USA
Broward County Parks, Oakland Park, Florida, USA
Nigel C. A. Pitman
Field Museum of Natural History, Chicago, IL, USA
John R. Poulsen
The Nature Conservancy, Boulder, USA
Nicholas School of the Environment, Duke University, Durham, USA
Ecology and Evolutionary Biology, University of Colorado, Boulder, USA
Akhilesh Raghubanshi
Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi 221005, India
Dipika Rana
School of Biological & Environmental Sciences, Shoolini University, Solan, H.P., India
Department of Botany, Sri Sai University, Palampur, Kangra, Himachal Pradesh 176081, India
Mirco Rodeghiero
Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38098 San Michele all’Adige (TN), Italy
Samir Rolim
Centro de Formação em Ciências Agroflorestais, Universidade Federal do Sul da Bahia, BR 415, km 29, Ilhéus-BA, 45613-204, Brazil
Purabi Saikia
Department of Botany, Institute of Science, Banaras Hindu University, Varanasi 221005, India
Peter Schall
Silviculture and Forest Ecology of the Temperate Zones, University of Göttingen, Göttingen, Germany
Dmitry Schepaschenko
International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
Siberian Federal University, Krasnoyarsk, Russia
Jochen Schöngart
National Institute for Amazonian Research (INPA), Manaus, Brazil
Vladimír Šebeň
National Forest Centre, Zvolen, Slovakia
Giacomo Sellan
Cirad, UMR EcoFoG (AgroParistech, CNRS, INRAE, Université des Antilles, Université de la Guyane), Campus Agronomique, Kourou, French Guiana
Carlos Alberto Silva
School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL 32611, USA
Marcos Silveira
Universidade Federal do Acre, Centro de Ciências Biológicas e da Natureza, Rio Branco, Acre, Brasil
Jamuna Singh
Ecosystems Analysis Laboratory, Department of Botany, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India
Ferry Slik
Environmental and Life Sciences, Faculty of Science, Universiti Brunei Darussalam, BE1410, Gadong, Brunei Darussalam
Jarosław Socha
University of Agriculture in Krakow, Faculty of Forestry, Krakow, Poland
José Daniel Soto
Museo de Historia Natural Noel Kempff Mercado; Universidad Autónoma Gabriel René Moreno, Bolivia
Alexandre F. Souza
Departamento de Ecologia, Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN, Brazil
Prashant K. Srivastava
Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi 221005, India
Hans ter Steege
Naturalis Biodiversity Center, Leiden, The Netherlands
Quantitative Biodiversity Dynamics, Faculty of Science, Utrecht University, The Netherlands
Krzysztof Stereńczak
Forest Research Institute, Braci Leśnej 3, Sękocin Stary, 05-090, Poland
Somaiah Sundarapandian
Department of Ecology and Environmental Sciences, Pondicherry University, Puducherry, India
Martin Svátek
Department of Forest Botany, Dendrology and Geobiocoenology, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
Jens-Christian Svenning
Department of Ecoscience, Aarhus University, Denmark
Xiaolu Tang
State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
Tianfu Yongxing Laboratory, Chengdu 610213, China
Raquel S. Thomas
Iwokrama International Centre for Rain Forest Conservation and Development, Guyana, South America
Antonio Tomao
Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Udine, Italy
Liam A. Trethowan
Herbarium, Royal Botanic Gardens, Kew, London, UK
Robert Tropek
Department of Ecology, Faculty of Science, Charles University, Prague, Czechia
Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czechia
Kalidas Upadhyaya
Department of Forestry, Mizoram University, Aizawl, Mizoram, India
Renato Valencia
Pontificia Universidad Católica del Ecuador, Quito, Ecuador
Rodolfo Vásquez
Missouri Botanical Garden – Peru; Herbario Selva Central Oxapampa – HOXA, Peru
Daniel Jose Vega-Nieva
Facultad de Ciencias Forestales y Ambientales, Universidad Juárez del Estado de Durango, México
Hans Verbeeck
Q-ForestLab, Department of Environment, Ghent University, Ghent, Belgium
Helder F. Viana
CERNAS-IPV Research Centre, Polytechnic Institute of Viseu, Campus Politécnico, Repeses, 3504-510 Viseu, Portugal
Centre for the Research and Technology of Agroenvironmental and Biological Sciences (CITAB), Inov4Agro, Universidade de Trás-os-Montes e Alto Douro (UTAD), Quinta de Prados, 5000-801 Vila Real, Portugal
Alexander Christian Vibrans
Department of Forest Engineering, Universidade Regional de Blumenau, Santa Catarina, Brazil
Simone A. Vieira
Núcleo de Estudos e Pesquisas Ambientais, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-970, Brazil
Barbara Vinceti
Bioversity International, Rome, Italy
Jason Vleminckx
Plant Ecology and Biogeochemistry lab, Faculty of Sciences, Université Libre de Bruxelles, 50 av. F.D Roosevelt, 1050 Brussels, Belgium
Vincent Antoine Vos
Instituto de Investigaciones Forestales de la Amazonía, Universidad Autónoma del Beni José Ballivián, Riberalta, Bolivia
Anna S. Vozmishcheva
Siberian Federal University, Krasnoyarsk, Russia
Foma Vozmitel
Forest Research Institute of the Karelian Research Centre of the Russian Academy of Sciences (FRI KarRC RAS), Petrozavodsk, Russia
State Nature Reserve «Denezhkin Kamen», Russia
Hayden Wagia
Papua New Guinea University of Technology, School of Forestry, Faculty of Natural Resources, Lae, Papua New Guinea
Hua-Feng Wang
Collaborative Innovation Center of Nanfan and High-Efficiency Tropical Agriculture, School of Breeding and Multiplication, Hainan University, Sanya 572025, China
School of Tropical Agriculture and Forestry, Hainan University, Haikou 570228, China
Eric K. Wasingya
Université de Kisangani, Fac Gest Ressources Nat Renouvelables, Kisangani, Democratic Republic of Congo; Institut National pour l’Etude et la Recherche Agronomiques, Centre de Recherche de Yangambi, Yangambi, Democratic Republic of Congo
Edward L. Webb
Viikki Tropical Resources Institute, Department of Forest Sciences, University of Helsinki, Finland
Helsinki Institute for Sustainability, University of Helsinki, Finland
Chemuku Wekesa
Kenya Forestry Research Institute, Coast Eco-Region Research Programme, P.O. Box 1078-80200, Malindi, Kenya
Verginia Wortel
Department of Forest Management, Centre for Agricultural Research in Suriname (CELOS), Paramaribo, Suriname
Emmanuel Kasongo Yakusu
Faculté de Gestion des Ressources Naturelles Renouvelables, Université de Kisangani, Kisangani, Democratic Republic of the Congo
Ghent University, Faculty of Bioscience Engineering, Laboratory of Wood Technology, Ghent, Belgium
Service of Wood Biology, Royal Museum for Central Africa, Tervuren, Belgium
Key Laboratory of Forest Ecology and Environment, China’s National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing, China
State Key Laboratory of Climate System Prediction and Risk Management, Nanjing University of Information Science and Technology, Nanjing, China
Angelica M. Almeyda Zambrano
School of Forest, Fisheries, and Geomatics Sciences, University of Florida, Gainesville, FL 32611, USA
Irié Casimir Zo-Bi
ESA & UMRI SAPT, Institut National Polytechnique Félix Houphouët-Boigny, BP 1093, Yamoussoukro, Côte d’Ivoire
Jingjing Liang
CORRESPONDING AUTHOR
Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
Forestry Division, Food and Agriculture Organization of the United Nations, Rome, Italy
Short summary
This study introduces the first global, spatially explicit dataset of tree diameter structure, capturing key aspects of forest organization, including average tree size, large-tree dominance, and within-stand variability. Built from over one million ground-based field plots combined with more than 50 satellite and environmental layers using machine learning, it provides a consistent representation of forest structure and supports ecosystem research, climate modeling, and forest management.
This study introduces the first global, spatially explicit dataset of tree diameter structure,...
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This is a nice global collaborative study bringing together a mindboggling number of tree DBH-measurements from across the globe, and using these to make 3 km-resolution global maps for a few key metrics.
This will be a highly valuable product for many as the need for more forest structural data increases. It’s a bit of a pity that the resolution is not higher though (1 km would have brought it in line with so many other datasets). Perhaps I’m missing a bit of discussion in the paper why a higher resolution was not feasible, despite the number of observations. I assume it has to do with the relatively low R2-values, which indicate the presence of a lot of noise and unexplained variance. Perhaps a discussion of that noise would also be helpful: what makes the data so noisy? Is it disturbance or land use history?
L1: I think ‘using a machine learning approach’ would read better
Abstract: I wonder if it makes sense to highlight some results as well. For example, do the findings confirm existing literature that temperature forests have the largest mean diameters (Dmean), or is that new information? In both cases it could be a nice thing to mention in the abstract so it gets very concrete what kind of information one can get out of this dataset. Related, wouldn’t it make sense to have one paragraph at the end of the paper to discuss if the observed patterns are at least roughly in line with the literature (and thus cite some references), or if these patterns are novel? That would also help readers to find ecological underpinnings of the observed patterns whenever they want to use the maps.
L514-515: it’s not intuitive to me what the difference between a ‘fixed-area plot’ and an ‘inventory unit’ is (besides the size). Why are they named such? Does an inventory unit not have a fixed-area? Is it not a plot?
L516: how exactly is data expanded? If you have DBHs for a number of trees in a plot, how do you get the DBHs from the trees in the surrounding area from there? Are the parameters (e.g., mean) sensitive to plot size and, if so, how does the scaling solve that if you don’t have information on the surrounding area?
L533: add an example of such a name, perhaps?
L549: I assume the exclusion based on the 10 cm threshold does not apply to the summing of multi-stem diameters? The order of sentences now makes it slightly misleading.
L551: how often was disturbance information available? Is there a risk that many observations influenced by disturbance are still included, because the information was not available? If this information was rare, satellite-based proxies of disturbance may have to be used.
L618: how did you screen for multicollinearity?
L639: values of what? Of all predictor layers?
L639: I’m a bit worried about the idea of extracting values only at the centroid of the pixel. Wouldn’t the mean of the pixel be more representative? What if now for example the centroid of the pixel just has a forest gap – would then the forest height (a 30 m resolution variable) be entirely unrepresentative for the pixel?
Table 2: could you make a clearer distinction between the categories? Now the covariates of a certain category are listed above the category-name (top-aligning might help, or adding a horizontal line between categories).
L677: do you have references that argue for modelling separately per ecozone? Intuitively, I would say that by reducing the environmental range in your dataset (which you do by splitting in ecozones) and the number of datapoints, you reduce the explanatory power of your model. Also, these machine learning models deal well with non-linearity, so why is the splitting necessary?
L693-695: separately across each model technique, or averaged across techniques?
L727: and which function for the OLS?
Figure 2: I’m surprised to see such high values – a lot of green colours e.g. in Europe, with values far above the mean and standard deviation as reported in Table 1.
Figure 2: do we see abrupt changes between ecozones, stemming from the running of separate models?
Finally, I would love to see a map of data coverage (i.e. observation points) in the main text.
Overall, a great dataset and a massive effort, congratulations!
Kind regards,
Jonas Lembrechts