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Macrolichens of Big Bend National Park, Texas

1976; American Bryological and Lichenological Society; Volume: 79; Issue: 3 Linguagem: Inglês

10.2307/3242369

1938-4378

Clifford M. Wetmore,

Archaeology and Natural History

One hundred thirteen taxa of foliose and fruticose lichens are reported from Big Bend National Park, keys to the macrolichens and lists of the localities visited are included. Many taxa were collected infrequently, which may indicate restricted local distributions in the park. New records for North America are: Peltula radicata (Ach.) Nyl., Rechingeria cribellifera (Nyl.) Serv., Heterodermia diademata (Tayl.) Awas. A new combination is made for Heterodermia rugulosa (Kurok.) Wetm. and it is recorded for the first time north of Mexico. Little has been published on the lichens of Big Bend National Park and only a few collectors have visited the area to collect lichens. The park is located in a large southern bend in the Rio Grande River at about 103'W and 29'N and includes the Chisos Mountains, which rise to almost 8000 feet (2438 m) elevation. In the summer of 1931 J. A. Steyermark and J. A. Moore collected in southwestern Texas and a list of eight lichen taxa from the Chisos Mountains was included in their report (Steyermark & Moore, 1933). In 1931 and 1932 E. Whitehouse collected in southwestern Texas and reported only Lecanora calcarea from Brewster County (Whitehouse, 1934), but no exact locality is given and it may not have been collected in the Chisos Mountains or in what is now the Park. I have seen one collection (Pseudevernia intensa) by E. R. Blakley made in 1952, and Thomson (1950) reported a Peltigera from the Park collected by Warnock in 1937. Thomson (1963) reported Physcia intermedia, collected by Darrow at Boot Springs in 1956 in the Chisos Mountains. The most extensive collecting in the Park prior to this study was done by R. Anderson and S. Shushan in 1959 when they made about 150 collections that included about 90 taxa. They did not publish on these collections, but the material was distributed and is occasionally listed in the literature. Four of these collections were issued by Weber in his exsiccata. In 1966 I collected in Big Bend National Park in connection with a revision of the Heppiaceae. In 1969 and 1970 I again collected in the Park, spending a month each time. On these trips I collected at 38 different localities and made 876 collections throughout the Park. All lichen taxa found at every locality were collected and about 177 taxa have been identified from these collections. Only the records of the Heppiaceae from the 1966 and 1969 collections have been published (Wetmore, 1970). This paper reports the macrolichens from Big Bend National Park. The microlichens will be covered in a later paper. 1 J wish to thank the personnel of Big Bend National Park for their cooperation, suggestions on collecting localities and permission to collect in the park. Botany Department, University of Minnesota, St. Paul, Minn. 55108. This content downloaded from 157.55.39.132 on Thu, 15 Sep 2016 06:12:28 UTC All use subject to http://about.jstor.org/terms 1976] WETMORE: MACROLICHENS OF BIG BEND NATIONAL PARK, TEXAS 297 The Chisos Mountains are outliers of the Rocky Mountains and consist of rugged mountains and ridges rising to above 7000 ft. (2100 m) in several places, the highest is Emory Peak which is 7800 ft. (2377 m). The Rio Grande River is about 2000 ft. (609 m) and the general plain is about 3000 ft. (914 m) above sea level. The extensive volcanic intrusions formed the higher peaks and are evident as dikes and volcanic ash deposits around the perimeter of the central core of mountains. There are granite outcrops in the Grapevine Hills, limestone on the plain and several kinds of igneous rocks in the Chisos Mountains. The complicated geological history and stratigraphy are summarized by Maxwell (1968), Wauer (1973) and Maxwell et al. (1972). Temperatures and precipitation in Big Bend National Park vary considerably because of the strong influence of the Chisos Mountains. Temperatures along the Rio Grande River and in the desert are near 100'F (38'C) in the summer, but near 850F (30'C) in the mountains. The rainy season is in the summer and occasionally snow falls in the mountains in the winter. Total precipitation is less than 10 inches (25.5 cm) at low elevations, but is considerably more in the mountains. The Chisos Mountains are a vegetational island located between the Front Range of the Rocky Mountains and the Sierra Madre of Mexico and are surrounded by the Chihuahuan Desert. Most of the park has desert shrub and desert grassland vegetation with species of cactus, acacia, agave and creosote bush. The grasslands were heavily grazed by livestock prior to the establishment of the park in 1944 which caused considerable damage to the vegetation. In the intermediate elevations oaks, pinyon pines and junipers occur. At the highest elevations ponderosa pine (Pinus ponderosa), douglas fir (Pseudotsuga menziesii) and arizona cypress (Cupressus arizonica) are found in the valleys and in one area on the high flanks of Emory Peak a stand of quaking aspen (Populus tremuloides) survives as a relict of more moist conditions of the past. Because of the location of the Chisos Mountains in relation to the main mountain ranges and deserts and because of the varied habitats and climates, the Big Bend area has a diverse flora with many species of potential phytogeographical significance. There are several examples of species of vascular plants which occur in Big Bend at only one or a few localities and are at the edges of their North American ranges. The same seems to be the case with some of the lichens.