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Distribution of Ephemeral Herbaceous Plants near Treeline in the Sierra Nevada, California, U.S.A.
Louise E. Jackson and L. C. Bliss
Arctic and Alpine Research
Vol. 14, No. 1 (Feb., 1982), pp. 33-43
Published by: INSTAAR, University of Colorado
Stable URL: http://www.jstor.org/stable/1550813
Page Count: 11
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Annuals and ephemeral perennials which become dormant early in the snow-free season are uncommon life forms in most alpine areas. In Slate Creek Valley in the Sierra Nevada, California, few of the numerous subalpine ephemeral species grow in alpine communities above 3400 m. Vegetation sampling within the subalpine zone showed that ephemeral species are most abundant in terraced Carex exserta communities on south-facing slopes. Within these communities, annuals were sampled most frequently on bare soil or lag gravel substrates while ephemeral perennials prefer bare soil or moss and lichen mats. Along a transect from the upper subalpine to the alpine, ephemerals, especially annuals, decrease within Carex exserta communities (15 to 5 species per site) while persistent perennials increase (10 to 14 species per site). Vegetation sampling found that most ephemeral species are best adapted to grow in communities with warm and moist soils for one to two months and in low plant cover which results in open, unshaded microsites. We hypothesize that ephemeral life forms are preadapted to succeed in the short subalpine growing season, but our data suggest that most such species require higher temperatures and longer water stress-free periods than are found above treeline in the Sierra Nevada.