Lichens and their distribution in Lewis and Clark Caverns State Park
Lichens are unique organisms composed of two to three different organisms living together in a symbiotic relationship. They occur in most terrestrial habitats and perform many valuable roles in an ecosystem. Many species of lichen are sensitive to airborne pollutants, making them good biological indicators of air quality. A high diversity of lichens can indicate a relatively stable environment. In this study, an exhaustive inventory of the lichen species in Lewis and Clark Caverns State Park, Jefferson County, Montana, was done by collecting from all substrates in 22 different sites. The distribution of species among seven vegetation types, frequency of growth forms, and substrate inhabitance are presented. One-hundred-sixty-four species were identified in the park. Crustose species were the most common (45%), while 40% were foliose, 5% were fruticose, 7% were squamulose and 3% were Cladonia species. Forty-six per cent occurred on rock, 32% on bark or wood 12% on moss, litter or other and 10% on soil. The greatest diversity of species was found in the mountain mahogany grasslands with 88 species collected. The smallest number of species was found in the willow grassland with only 20 species collected. The large diversity of lichens present in Lewis and Clark Caverns State Park suggests that the parks resources are relatively undisturbed. In comparison with other pristine sites in Montana and Wyoming, Lewis and Clark Caverns State Park has the most species in common with Yellowstone National Park, having 123 shared species, and shares the highest similarity index (Jaccard's Similarity Index) with Grand Teton National Park (36% ISj). In addition, our study extended the known range of distribution for Thyrea confusa, which has not been previously reported in Montana.