The Alliance is aware the Yale University School of Forestry and Environmental Studies released an important study in the journal Nature in 2015 estimating that there are about three trillion trees on earth with a diameter of five inches or more. The study by Thomas Crowther et al was entitled: "Mapping tree density at a global scale" (Nature, September 10, 2015). The trees to humans ratio is approximately 422:1. The Alliance plans to build on insights derived from this study.
Leonardo da Vinci observed in the early 16th Century that the cross sections of sub-branches approximately equal the area of parent branches. Within the past decade, the patterns of tree branching have been determined to be primarily a factor of structural wind resistance rather than internal water flow. For more information, see Manuel Lima, The Book of Trees, NY: Princeton Architectural Press, 2014, Page 26.