Gil Nelson is a botanist and the coauthor of the National Wildlife Federation Field Guide to Trees of North America and the National Audubon Society Field Guide to the Southeastern States. Christopher J. Earle is an ecologist whose specialties include forest ecology and conifer biology. Richard Spellenberg, a botanist and specialist in plant taxonomy, is the author of the National Audubon Society Field Guide to Wildflowers, Western Region. David More is regarded as one of the finest botanical illustrators in the world. He has illustrated a number of tree guides, including the acclaimed Collins Tree Guide and The Illustrated Encyclopedia of Trees (Princeton).