Roe-Andersen, Susan .
Ecology of alpine and subalpine populations of Botrychium pumicola (pumice moonwort), a rare Cascade Range endemic.
Subalpine and alpine populations of Botrychium pumicola (Ophioglossaceae), pumice moonwort, are restricted to volcanic habitats in the Cascade Range of central and southern Oregon and extreme northern California. The disjunct distribution of this threatened species and its absence from habitat that appears suitable is of conservation and land management concern. The focus of this study was to determine if adjacent areas with and without B. pumicola differ in abiotic and biotic factors and to understand how these factors affect the distribution of the species. Botrychium pumicola occurs on exposed, windswept volcanic domes, ridgelines and summits, however the species is not restricted to pumice substrates as previously reported. Populations occur on flat to steep slopes up to 27Â°, and aspects of N, E, SE, S, SW, and W. South, southwest, and west aspects were preferred. Soil potassium levels and soil density were higher, and soil temperatures lower in plots with B. pumicola. Botrychium pumicola populations occur with a diverse suite of sparse herbaceous perennial plants. A nearest neighbor analysis for B. pumicola and its plant associate showed a clumped dispersion. Species richness of plant associates was similar in areas with and without B. pumicola. An investigation of the spore bank revealed a low spore density for all populations including one with 1300 B. pumicola individuals. The disjunct distribution of B. pumicola may be influenced by a variety of factors creating “habitat islands” suitable for growth and development of B. pumicola spores, gameotophytes and sporophytes and their obligate AM fungal symbionts.
This study increases the understanding of the factors affecting the distribution of a Cascade Range endemic and has implications for rare species management in National Parks, National Forests and other Federal Lands.
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1 - Southern Oregon University, Biology, PO Box 35, Crater Lake, OR, 97604, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 556B/Convention Center
Date: Monday, August 2nd, 2010
Time: 10:45 AM