Distribution and diversity of alpine lichens: biotic and abiotic factors influencing alpine lichen communities in the northeast Olympic and North Cascade Mountains
Glew, Katherine A. (Katherine Anne)
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Alpine lichens from six specific sites in the northeastern Olympic and North Cascade Mountains were studied. Sites included Elk Mountain, Deer Park, and Buckhorn cirque from the Olympic Mountains; and Skyline Divide, Slate Peak and the Tatie Peak area of the North Cascade Mountains. Lichens and vascular plants, and bryophytes were inventoried from each site. Over 170 species of lichen were identified, representing more than 70 genera. Of these, 65% were macrolichens and 35% were microlichens. For lichen percent cover from all sites, 2% were foliose, 18% were fruticose and 8% were crustose. Diversity analyses showed that drier exposed fell field sites with south and southwestern aspects had a higher species richness and diversity index. Lichens found on eastern and northeastern slopes had higher snow accumulations during the winter months, were slow to lose their snow in the summer, and mesic due to the snow melt run-off. Ericaceous plants dominated these areas affecting soil pH, other plant associations, and the diversity of lichens. Correlations and ordination analyses were employed to determine the biotic and abiotic factors influencing lichen distributions. Abiotic factors included slope, elevation, aspect, soil pH, substrate stability, substrate type, and moisture class. Biotic factors included the percent vegetation cover and plant species composition found within each quadrat. DCA and CCA analyses displayed similar distributions of lichens within the ordinations. Abiotic factors showed a strong relationship between slope, aspect, and substrate type. Substrate appeared to be a leading factor influencing lichen communities within the sites. Saxicolous lichen communities were influenced by the parent material of the rock and its pH. Vegetation significantly influenced the type of lichens on the sites. Dry tundra locations exhibited a positive correlation between lichen cover and plant cover. At the mesic sites, there was a negative relationship between plant cover and lichen cover. Species of plants associated with lichens were not as important as the assemblage of plants found at each site. Plants were converted into functional groups to represent the types of "structural framework" they provide for the lichens. Many of the fruticose lichens form associations with these functional groups of plants.
- Biology