The global biogeography of tree leaf form and habit
Authors: Ma Haozhi , Crowther Thomas W. , Mo Lidong , Maynard Daniel S. , Renner Susanne S. , van den Hoogen Johan , Zou Yibiao , Liang Jingjing , de-Miguel Sergio , Nabuurs Gert-Jan , Reich Peter B. , Niinemets Ülo , Abegg Meinrad , Adou Yao Yves C. , Alberti Giorgio , Almeyda Zambrano Angelica M. , Alvarado Braulio Vilchez , Alvarez-Dávila Esteban , Alvarez-Loayza Patricia , Alves Luciana F. , Ammer Christian , Antón-Fernández Clara , Araujo-Murakami Alejandro , Arroyo Luzmila , Avitabile Valerio , Aymard Gerardo A. , Baker Timothy R. , Bałazy Radomir , Banki Olaf , Barroso Jorcely G. , Bastian Meredith L. , Bastin Jean-Francois , Birigazzi Luca , Birnbaum Philippe , Bitariho Robert , Boeckx Pascal , Bongers Frans , Bouriaud Olivier , Brancalion Pedro H. S. , Brandl Susanne , Brearley Francis Q. , Brienen Roel , Broadbent Eben N. , Bruelheide Helge , Bussotti Filippo , Cazzolla Gatti Roberto , César Ricardo G. , Cesljar Goran , Chazdon Robin , Chen Han Y. H. , Chisholm Chelsea , Cho Hyunkook , Cienciala Emil , Clark Connie , Clark David , Colletta Gabriel D. , Coomes David A. , Valverde Fernando Cornejo , Corral-Rivas José J. , Crim Philip M. , Cumming Jonathan R. , Dayanandan Selvadurai , de Gasper André L. , Decuyper Mathieu , Derroire Géraldine , DeVries Ben , Djordjevic Ilija , Dolezal Jiri , Dourdain Aurélie , Engone Obiang Nestor Laurier , Enquist Brian J. , Eyre Teresa J. , Fandohan Adandé Belarmain , Fayle Tom M. , Feldpausch Ted R. , Ferreira Leandro V. , Finér Leena , Fischer Markus , Fletcher Christine , Fridman Jonas , Frizzera Lorenzo , Gamarra Javier G. P. , Gianelle Damiano , Glick Henry B. , Harris David J. , Hector Andrew , Hemp Andreas , Hengeveld Geerten , Hérault Bruno , Herbohn John L. , Herold Martin , Hillers Annika , Honorio Coronado Eurídice N. , Hui Cang , Ibanez Thomas T. , Amaral Iêda , Imai Nobuo , Jagodziński Andrzej M. , Jaroszewicz Bogdan , Johannsen Vivian Kvist , Joly Carlos A. , Jucker Tommaso , Jung Ilbin , Karminov Viktor , Kartawinata Kuswata , Kearsley Elizabeth , Kenfack David , Kennard Deborah K. , Kepfer-Rojas Sebastian , Keppel Gunnar , Khan Mohammed Latif , Killeen Timothy J. , Kim Hyun Seok , Kitayama Kanehiro , Köhl Michael , Korjus Henn , Kraxner Florian , Kucher Dmitry , Laarmann Diana , Lang Mait , Lewis Simon L. , Lu Huicui , Lukina Natalia V. , Maitner Brian S. , Malhi Yadvinder , Marcon Eric , Marimon Beatriz Schwantes , Marimon-Junior Ben Hur , Marshall Andrew R. , Martin Emanuel H. , Meave Jorge A. , Melo-Cruz Omar , Mendoza Casimiro , Merow Cory , Monteagudo Mendoza Abel , Moreno Vanessa S. , Mukul Sharif A. , Mundhenk Philip , Nava-Miranda María Guadalupe , Neill David , Neldner Victor J. , Nevenic Radovan V. , Ngugi Michael R. , Niklaus Pascal A. , Oleksyn Jacek , Ontikov Petr , Ortiz-Malavasi Edgar , Pan Yude , Paquette Alain , Parada-Gutierrez Alexander , Parfenova Elena I. , Park Minjee , Parren Marc , Parthasarathy Narayanaswamy , Peri Pablo L. , Pfautsch Sebastian , Phillips Oliver L. , Picard Nicolas , Piedade Maria Teresa F. , Piotto Daniel , Pitman Nigel C. A. , Mendoza-Polo Irina , Poulsen Axel D. , Poulsen John R. , Pretzsch Hans , Ramirez Arevalo Freddy , Restrepo-Correa Zorayda , Rodeghiero Mirco , Rolim Samir G. , Roopsind Anand , Rovero Francesco , Rutishauser Ervan , Saikia Purabi , Salas-Eljatib Christian , Saner Philippe , Schall Peter , Schelhaas Mart-Jan , Schepaschenko Dmitry , Scherer-Lorenzen Michael , Schmid Bernhard , Schöngart Jochen , Searle Eric B. , Seben Vladimír , Serra-Diaz Josep M. , Sheil Douglas , Shvidenko Anatoly Z. , Silva-Espejo Javier E. , Silveira Marcos , Singh James , Sist Plinio , Slik Ferry , Sonké Bonaventure , Souza Alexandre F. , Miścicki Stanislaw , Stereńczak Krzysztof J. , Svenning Jens-Christian , Svoboda Miroslav , Swanepoel Ben , Targhetta Natalia , Tchebakova Nadja , ter Steege Hans , Thomas Raquel , Tikhonova Elena , Umunay Peter M. , Usoltsev Vladimir A. , Valencia Renato , Valladares Fernando , van der Plas Fons , Van Do Tran , van Nuland Michael E. , Vasquez Rodolfo M. , Verbeeck Hans , Viana Helder , Vibrans Alexander C. , Vieira Simone , von Gadow Klaus , Wang Hua-Feng , Watson James V. , Werner Gijsbert D. A. , Westerlund Bertil , Wiser Susan K. , Wittmann Florian , Woell Hannsjoerg , Wortel Verginia , Zagt Roderick , Zawiła-Niedźwiecki Tomasz , Zhang Chunyu , Zhao Xiuhai , Zhou Mo , Zhu Zhi-Xin , Zo-Bi Irie C. , Zohner Constantin M. 
Published: October 2023

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling.