How much of the world is woody?

Richard G. FitzJohn†, Matthew W. Pennell*†, Amy E. Zanne, Peter F. Stevens, David C. Tank and William K. Cornwell Biodiversity Research Centre and Department of Zoology University of British Columbia, Vancouver, BC V6G 1Z4, Canada; Department of Biological Sciences Macquarie University, Sydney, NSW 2109, Australia; Department of Biological Sciences and Institute for Bioinformatics and Evolutionary Studies, University of Idaho, Moscow, ID 83844, USA; National Evolutionary Synthesis Center, Durham, NC 27705, USA; Department of Biological Sciences, George Washington University, Washington, DC 20052, USA; Center for Conservation and Sustainable, Development Missouri Botanical Garden, Louis, MO 63121, USA; Department of Biology, University of Missouri, St. Louis, MO 63166,USA; Missouri Botanical Garden, PO Box 299, St Louis, MO 63166-0299, USA; Department of Systems Ecology, VU University, 1081 HV, Amsterdam, The Netherlands; and Evolution & Ecology Research Centre, School of Biological Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia