Bailey & Bailey: Woody Plants of National Parks 7 



cover any extensive areas, but aspen {Popiilus tremulo.des) may be found 

 along the lower water courses. 



The upper forests of the Hudsonian Life Zone are characterized by fine 

 stands of mountain hemlock (Tsuga Mertensiana) with whitebark pine {Pmus 

 albicaidis) following the ridges up to nearly 10,000 feet. Characteristic shrub 

 species are pinemat manzanita (Arctostaphylos nevadensis) , subalpine spiraea 

 {Spiraea densiflora) , and others. 



YosEMiTE National Park 



Yosemite National Park, one of the best known of our national parks, 

 is famous for its steep-walled glacier-carved Yosemite Valley. Elevations 

 range from about 13,100 feet on the Sierra Nevada Crest to 2.000 feet at 

 EI Portal, the Merced Valley entrance. Precipitation averages 33 inches 

 yearly in the Yosemite Valley at about 4,000 feet elevation. 



Because of the great range in elevation, the vegetation cover is quite 

 varied and often complex. Along the western boundary is the lower foothill 

 area covered for the most part with grassland and scattered oak trees, the 

 principal species being interior live oak (Qiierciis Wisl.::eni) and canyon live 

 cak {Quercus chrysolepis) . Occasional trees of digger pine {Pmus sabiniana) 

 may be seen in this vegetation belt. Other associates are California buckeye 

 (Aesculus calijornica), buckbrush ceanothus (Ceanothiis ciineatus) , yerba 

 santa (Enodictyon caltfornicum) , and Mariposa manzanita {Arctostaphylos 

 mariposa) . 



Above the foothill area is a forest belt in which ponderosa pme {Pmus 

 ponderosa), sugar pine {Pmus Lambertiana) , white fir {Abies concolor), and 

 incense cedar {Libocedrus decurrens) are the common tree species, extending 

 up to about 6,500 feet. California black oak {Q^uercus Kelloggi) is common 

 in the valleys. Common shrubby species include greenleaf manzanita 

 {Arctostaphylos patula), California chinquapin {Castanopsis sempervirens) , 

 deerbrush ceanothus {Ceanothus integerr.mus) , and western thimbleberry 

 {Rubus parviflorus) . The groves of bigtree {Sequoia gigantea) are restricted 

 to this forest belt. 



In the upper part of this area the forest becomes predominantly Jeffrey 

 pine {Pmus Jeffreyi) and California red fir {Abies magnifica) and these 

 remain dominant up to about 9,000 feet or higher. Mountain whitethorn 

 ceanothus {Ceanothus cordulatus) and huckleberry oak {Quercus vaccmifolia) 

 become important shrubby species in this belt. Pinemat manzanita {Arcto- 

 staphylos nevadensis) and wax currant {Ribes cereum) are also common. 

 Much of the forest on the eastern part of the park is composed of lodgepole 

 pine {Pmus contorta) which may occur in pure stands or mixed with moun- 

 tain hemlock {Tsuga Mertensiana) . On ridges and barren granite slopes 

 whitebark pine {Pinus albicaidis) and Sierra juniper {Juniperus occidental.s) 

 are characteristic associates. Shrubby plants found at the higher elevations, 

 up to timberline and above include low willows {Salix), bush cinquefoil 

 {Potentilla fruticosa) , white heather {Cassiope Mertensiana), and f3rewer 

 mountainheath {Phyllodoce Brewen). 



