Regional gradients in lichen communities of the Southeast United States

Epiphytic macrolichens were sampled in 203, 0.38 ha plots in the Southeast United States. 176 lichen species were encountered. Gradient analysis revealed two major regional gradients in lichen communities. A multivariate model based on non-metric multidimensional scaling was used To assign gradient scores to plots, based on lichen species composition. The strongest gradient in the lichen communities corresponded to a macroclimactic gradient from the coast through the Piedmont to the Appalachian Mountains. The second major gradient was correlated with air quality, with pollution-tolerant species and lower species richness in 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 higher diversity in the mountains and lower diversity on the Piedmont and coast.