Most academic botany or biology departments do not have lichenologists. Here in the United States, lichen deserts are well known in our cities and nearby rural areas, but are unfortunately poorly documented. Sensitive species must be studied and monitored to determine the effects of air pollutants. Documented lichen deserts in the United States and Canada. Strong anecdotal evidence exists that lichen deserts also occur in most major cities.
Some lichens are unique to old-growth forests.
Other old-growth forest lichens, including Alectoria sarmentosa , Lobaria scrobiculata , and Ramalina thrausta , are now quite rare in the eastern United States because of habitat destruction and loss. In addition, scientific overcollecting may become a problem for lichens. One species, Gymnoderma lineare , was overcollected in Great Smoky Mountains National Park, Tennessee, in the late 1970's, and is now proposed for federal listing as endangered. Some hobby overcollecting of lichens for dye materials or architectural tree models is thought to be a problem in a few areas, but is not well documented. With fewer universities offering training in the discipline, fewer surveys and lists of floras being done, less literature being published, and at the same time lichens disappearing from our ecosystems, it is clear that the science is heading the opposite direction of what is needed.