14 American Midland Naturalist Monograph No. 4 



The ridge tops along the southern half of the plateau are covered for 

 the most part with luxuriant stands of almost pure pinon-juniper forest. The 

 species are Pmus edulis and Juniperus utahensis. Shrubby associates in this 

 forest on the plateau and extending down onto the upper canyon walls in- 

 clude such species as mountain mahogany (Cercocarpus montanus), cliffrose 

 {Cowania Stansburiana), fendlera (Fendlera rupicola), Spanish bayonet 

 (Yucca baccaia), Gambel oak (Quercus Gambeli), and serviceberry (Amelan- 

 chier utahensis) . 



The northern end of the plateau has a vegetation cover consisting of 

 almost pure thickets of Rocky Mountain white oak (Quercus utahensis) and 

 Gambel oak (Quercus Gambeli), interrupted now and then by patches of 

 grassland or sagebrush. In these open areas big sagebrush (Artemisia tri- 

 dentata), other species of Artemisia, and species of rabbitbrush (Chryso- 

 thamus) are common along with herbaceous plants. 



Douglas fir (Pseudotsuga taxijolia) occurs in a few places in protected 

 spots, particularly at the northern end of the park and ponderosa pine, 

 although comparatively rare, is found in a few spots. Such xerophytic species 

 as greasewood (Sarcobatus vermiculatus) , shadscale (Atriplex confertifolia), 

 fourwing saltbush (Atriplex canescens), and Nuttall saltbush (A. Nuttalli) 

 are characteristic of the lower canyon bottoms and the escarpment face at the 

 northern end of the park. 



Bryce Canyon National Park 



Bryce Canyon National Park consists principally of a series of amphi- 

 theaters formed in the cliff wall where the Paunsaugunt Plateau breaks off 

 into the Paria Valley to the east. Bryce Canyon is the name given to one 

 of the larger of these amphitheaters. A unique type of erosion of the red 

 and white sandstone has resulted in a series of very ornate and fantastic forma- 

 tions which can support practically no plant growth. In the hot dry amphi- 

 theater canyons, which descend to elevations of 1,000 feet below the plateau, 

 the vegetation cover consists mainly of a thin stunted growth of piiion (P.nus 

 edulis), Utah juniper (Juniperus utahensis), and desert types of shrubs. 



On the north end of the plateau, which ranges in elevation from about 

 7,600 to 9,000 feet and with an average annual rainfall of about 14 inches, 

 the forest cover is composed almost etirely of ponderosa pine (Pinus pon- 

 derosa) . Around park headquarters at about 8,000 feet the pine is mixed 

 with white fir (Abies concolor) and Douglas fir (Pseudotsuga taxifolia) . 

 These gradually replace it until at Rainbow Point (9,091 feet) none is found. 

 Bristlecone pine (P.nus aristata) occurs also at Rainbow Point as well as in 

 several places just below the edge of the plateau. Shrubby undergrowth is 

 not abundant in the forests of the plateau but a number of species are found 

 in openings or along the edge of the rims. Characteristic among these are 

 greenleaf manzanita (Arctostaphylos patula), mountain mahogany (Cerco- 

 carpus montanus and C. ledifolius) , bitterbrush (Purshia tridentata) , smooth 

 rockspirea (Holodiscus discolor var. glabrescens) , Martin ceanothus (Ceano- 

 thus Martini), Gambel oak (Quercus Gambeli), and big sagebrush (Arte- 

 misia tridentata) . 



