The Mosses of Lassen Volcanic National Park, California

Abstract

Twenty-six families, 67 genera, 145 species, and four varieties of mosses are reported from Lassen Volcanic National Park, California. Two species, Andreaea nivalis Hook. and Polytrichum sexangulare Brid., are new to California. Mielichhoferia tehamensis Showers, a recently described species, is endemic to the Lassen Park region. Lassen Volcanic National Park is located in northeastern California on the crest of the southern Cascade Range at approximately 40'30'N, 121'25'W. The elevational range within the park is about 1600 m, with the lowest point, 1590 m, in Warner Valley and the highest point, 3186 m, at the summit of Lassen Peak. Included in the park are 43,000 hectares of forests, subalpine meadows, volcanic cones, and lava flows of recent origin. From 1914 until 1921 a series of volcanic eruptions from Lassen Peak caused considerable damage to surrounding areas and created a six km2 devastated area. During the Pleistocene, the Lassen Park region experienced extensive glacial activity. Mount Tehama, an ancient composite volcano, dominated the southwestern part of the Park area prior to the formation of Lassen Peak. It once stood over 3500 m before it was deeply carved by glaciers. More than 610 m of elevation of the summit have disappeared because of subsidence and glacial scouring. Glacial polish and erratics, and the typical U-shaped valleys of Warner Valley and Blue Lake Canyon provide further evidence of past glacial activity. The climate of northern California and Lassen Volcanic National Park is characterized by cool, moist winters and, in general, warm, dry summers. Little precipitation falls during the summer months when hot, dry winds blow from the Sacramento Valley. At Manzanita Lake, at 1783 m, average yearly precipitation is 196 cm with 85% falling between October and April. Winter storms produce a deep snow cover throughout the Park. Snows above 2135 m remain until summer with some alpine lakes staying frozen until late July. The designation of plant communities within Lassen Volcanic National Park corresponds to those described by Munz and Keck (1959) as follows: Yellow Pine Forest (Pinus ponderosa Dougl., P. jeffreyi Grev. & Balf., and Abies concolor (Gord. & Glend.) Lindl.); Red Fir Forest (Abies magnifica Murr. and Pinus monticola Don); Subalpine Forest (Pinus albicaulis Engel., P. contorta var. murrayana (Grev. & Balf.) Critchf., and Tsuga mertensiana (Bong.) Carr.); and Alpine Fell Fields. Mosses are poorly represented both on the forest floor and as epiphytes on hardwoods and conifers. Because of the availability of moisture, the greatest diversity of moss species occurs in and around seepages, meadows, and the banks of streams. Mosses are uncommon to rare in much of the Park above 2700 m. The recent volcanic activity, the unstable volcanic ash, and the extremes of climate may account for this paucity. Although Lassen Volcanic National Park is situated in close proximity to the Sierra Nevada, many elements of its vascular plant flora (Gillett et al. 1961) and moss flora are allied to the Cascade Range of Oregon and Washington. Both Andreaea nivalis Hook. and Polytrichum sexangulare Brid. are reported here as new to California. They grow in similar habitats on cool, shaded, north-facing rocks and on soil 007-2745/82/324-328$0.65/0 This content downloaded from 157.55.39.96 on Mon, 18 Apr 2016 08:47:56 UTC All use subject to http://about.jstor.org/terms 1982] SHOWERS: MOSSES OF LASSEN PARK 325 over rock where snow remains until late in the season. Neither species occurs farther south than Lassen Park and both possess a more northerly distribution across North America into Europe in mountainous regions. Collections of mosses were made over several summers from 1974 to 1980 while the author was a ranger-naturalist at Lassen Volanic National Park. Voucher specimens are deposited in the herbarium at San Francisco State University (sFsu). Duplicate specimens are housed in the herbarium at the headquarters of Lassen Volcanic National Park, Mineral, California. Nomenclature conforms largely to Crum, Steere and Anderson (1973). One representative specimen of each taxon is cited by the author's collection numbers in the text. This work is in partial fulfillment of a Master of Arts Degree at San Francisco