Epiphytic macrolichens were sampled in 203, 0.38 ha plots in the South
east United States. 176 lichen species were encountered. Gradient anal
ysis revealed two major regional gradients in lichen communities. A mu
ltivariate model based on non-metric multidimensional scaling was used
To assign gradient scores to plots, based on lichen species compositi
on. The strongest gradient in the lichen communities corresponded to a
macroclimactic gradient from the coast through the Piedmont to the Ap
palachian Mountains. The second major gradient was correlated with air
quality, with pollution-tolerant species and lower species richness i
n urban and industrial areas, and pollution-sensitive species and high
species richness in cleaner areas. Epiphytic macrolichens were sparse
in urban areas with heavy industry. In many rural areas, lichens were
luxuriant and diverse. Species richness was locally variable and only
weakly related to the coast-to-mountains gradient, with somewhat high
er diversity in the mountains and lower diversity on the Piedmont and
coast.