Samuel B. St. Clair and Larry L. St. Clair, Botany and Range Science

Lichens are two organisms (alga, and fungus) that live in a symbiotic relationship. The algae provides energy for the fungus and the fungus protects the algae. Between 1874 and 1992 several sites along the front range of Colorado were examined for lichen diversity. But until recently little was known about the lichens in Southwestern Colorado. However, in the past five years lichenological work in the region has been conducted in connection with the establishment of a lichen air quality biomonitoring program and baseline in the San Juan Rio Grande National Forest.

Stony Pass, a high mountain Pass in the San Juan Mountains of southwestern Colorado, is one of the sites studied under this program. Elevation at the pass is approximately 3840m. The pass is above timberline and has a typical alpine tundra type vascular plant community, including Acomastylis rossii, Bistorta bistortoides, Castilleja occidentalis, Phacelia sericea, Potentilla pulcherrima, rydbergia grandiflora, Salix arctica, Salix reticulata, Selaginella densa, and Trifolium attenuatum.

At the site specimens were carefully removed from the soil using a collecting knife or from rock substrates using hammer and chisel. In some cases specimens were removed with a small amount of substrate material. All specimens were placed in labeled paper sacks and returned to the Herbarium of Nonvascular Cryptogams at Brigham Young University. Specimens were then cleaned, trimmed, and lightly pressed. Subsequently, specimens were mounted on labeled herbarium cards, placed in permanent herbarium packets, and assigned Herbarium numbers.

Specimens were identified using standard lichen keys, taxonmic treatises and by making comparisons with herbarium material. Standard chemical spot tests, and where necessary, thinlayered chromatography techniques were used to finalize species identifications.

Sixty-eight lichen species in 41 genera are reported for Stony Pass, San Juan County, Colorado. Candelariella reflexa, Collema ceraniscum, and dermatocarpon lorenzianum are reported as new state records for Colorado.

The lichen flora at Stony pass is diverse and well-developed. Stony Pass is dominated by Arctic Elemental species(78%); with Temperate element species comprising the balance of the flora. In comparing the lichen flora at Stony Pass with other alpine tundra sites in the Rocky Mountains, Stony Pass has the most species in common with Mt. Audubon in north central Colorado (40 out of 68 species). However, in terms of the degree of domination by Arctic Element species the flora at Stony Pass is more similar to two sites in north central and south central New Mexico (Lake Peak and Sierra Blanca Peak). The total contribution of Temperate Element species at most Rocky Mountain alpine tundra sites seems to be somewhat unique form site to site; with three New Mexico sites (Local Basin, Lake Peak and Sierra Blanca Peak) sharing 5-6 species in common, while Mt. Audubon and Stony Pass share only 2-3 species in common with other sites. The contribution of Temperate Element species to each alpine tundra site tends to be the most important factor influencing the degree of similarity between any two sites. Overall, the Arctic element of Rocky Mountain alpine tundra lichen floras tends to be more homogenous across sites.