Results from genus-level analyses of phylogenetically independent contrasts of N fixation versus successional indices.

*STW: shade tolerance, geographically weighted by shade tolerance in each grid cell; SAW-mean and SAW-max: mean stand age, geographically weighted by mean and maximum stand age in each grid cell, respectively. †Each test was performed at two phylogenetic scales: all U.S. angiosperm trees and the potentially N-fixing clade (PNFC; a subclade of the angiosperm phylogeny). ‡‘Discrete’ means that each genus was treated as an N fixer or not, whereas ‘continuous’ means that each genus was assigned the proportion of species that fix N (this proportion is either 0 or 1 in all U.S. tree genera). ¶P values are from one tailed tests. Significant or marginally significant P values are in bold.