Humans are squeezing and polluting lichen habitats in the Pacific Northwest. These activities favor common, easily dispersed, pollution-tolerant species at the expense of rare, weakly dispersing, sensitive species.
Certain habitats form enclaves for these rarer species. The most important habitats for these -- the last best lichen places -- vary with position in the landscape (Table 1). The threats also depend on geography.
See a list of the last best lichen places, their threats, and protections.