Alwyn H. Gentry, arguably one of the world s leading authorities on the botany of tropical America, died when his airplane crashed into an isolated mountain ridge in western Ecuador on August 3, 1993. In addition to his impressive studies on the systematics of Bignoniaceae and tropical floristics, Gentry had been involved since the early 1970s in building a unique data set of tropical and temperate forest samples. In this major undertaking, Gentry was motivated by the fundamental questions of how and why forest diversity and floristic composition vary from one location to another. Many of his publications examine the correlations between diversity and taxonomic composition of forests with a variety of environmental variables, particularly precipitation, elevations, and latitude. Over 22 years, he collected data from 226 sites on six continents. Gentry and his collaborators collected all plants with stem diameters equal to or exceeding 2.5 cm diameter at breast height (dbh) along ten 2 x 50 m transects, totaling a tenth of a hectare at each site.
This volume summarizes the data from each site, including environmental and diversity information and a taxonomic summary of the species that were encountered. The volume also provides full context for the information including a discussion of the history of Gentry's transect studies, an in-depth description of the methodology used to collect the data, a summary of the patterns arising from the overall results, and a summary of the significance of the studies. As a complement to the data, color reproductions of 73 of the extensive collection of Gentry s slides deposited in the archives of the library of the Missouri Botanical Garden are presented.