274 TH E STUDY OF PLANT COMMUNITIES * Chapter X 



zone of Finns contorta-Tsuga mertensiana dominance. Although 

 P. contort a is successional to Abies magnified at lower altitudes, it, 

 with hemlock, has climax characteristics in this zone. This would 

 suggest three f aciations for the subalpine zone, namely, white bark 

 pine or timber line f aciation, lodgepole pine-hemlock through the 

 upper part of the zone, and red fir, which, from the lower margin 

 upward, occupies the major part of the zone. 



Montane Zone —The altitudinal range of this zone lies between 

 about 2,000-6,000 feet in the Cascades, 4,000-7,000 feet in the cen- 

 tral Sierra, and 5,000-8,000 feet or more in the south. Five or six 

 principal species have climax characteristics and may appear in 

 any combination at any altitude. However, the upper and lower 

 parts of the zone tend to have consistent vegetational differ- 

 ences. 69 ' 144 White fir (Abies concolor) is usually the important 

 dominant in the upper part of the zone, sometimes in pure stands, 

 and decreases markedly at lower elevations. Lower down, incense 

 cedar (Libocedrus decurrens), predominating on the most favor- 

 able sites, sugar pine (P. lambertiana) , Jeffrey pine (P. jeffreyi), 

 ponderosa pine, and Douglas fir are the species of importance. 

 Douglas fir is more abundant in the north than in the south. 151 

 Sugar pine and Jeffrey pine are more conspicuous than ponderosa 

 pine at the upper altitudes, a logical arrangement since the latter 

 is the most drought-resistant of the major species. 



Fire subclimaxes are formed by Pinns attenuata, P. muricata, and 

 P. radiata in different parts of the range 268 although preceded by 

 dense chaparral communities of species of Arctostaphylos, Ceano- 

 thus, Rhamnus, etc., which may last for years. 



Included in the montane zone, on the western slope, are the for- 

 ests of giant redwood (Sequoia gigantea), at altitudes of 4,500- 

 6,000 feet. Once widespread, they now occur only southward 

 from the latitude of San Francisco in a disrupted zone. Their pres- 

 ent best development is in the central Sierra where they reproduce 

 but do not spread. Sugar pine, ponderosa pine, and incense cedar 

 are common associates. 



Foothills (Woodland) Zone —As in the Rockies, the vegetation 

 of the lower slopes and foothills is made up of coniferous and 

 scrub associations, but they are not as sharply separated here. The 

 zone ranges between about 1,500 and 4,000 feet. In the upper part, 



