CHAPARRAL COMMUNITIES 245 



Francisco Bay with some small islands still farther south. In Wash- 

 ington and Oregon there are large areas that are occupied by Douglas 

 fir in almost pure stand. Associated with this species, however, are 

 the western hemlock {Tsuga heterophylla) and white cedar {Thuja 

 plicata). These two species were formerly much more abundant. 

 The sitka spruce (Picea sifchensis) is an important constituent near 

 the seacoast and in northern California occurs the famous redwood 

 (Sequoia sempervirens) which is confined largely to the fog belt along 

 the coast. It may well be claimed that the coastal forest is the most 

 magnificent coniferous forest in the world. Because of the moderate 

 temperatures, excessive rainfall which ranges from 50 to 120 inches, 

 and frequent fogs, growth is very luxuriant and mature trees reach 

 heights of 200 to 300 feet and trunk diameters of 15 to 20 feet. 



145. Chaparral Communities.— Chaparral communities are domi- 

 nated by shrubs (Fig. 110). They are more xeric than forests but 

 somewhat less xeric than most grasslands and much less xeric than 

 desert scrub communities which also have shrubs as dominants. 

 Most chaparral communities occur where the rainfall is between 

 10 and 20 inches and especially where a large percentage of the rain 

 falls in winter. There are two general types of chaparral, deciduous 

 and sclerophyllous or evergreen. 



The deciduous chaparral association is at its best in Colorado, 

 eastern Utah and northern New INIexico where, for the most part, 

 it occupies an intermediate position between forest and grassland. 

 Perhaps the most characteristic dominant is Gambel oak {Quercus 

 utahensw). Almost equally important are the mountain mahogany 

 {Cercocarpus parvifolius), the squawbush (Rhus trilohata), the west- 

 ern chokecherry (Prwiiis demissa), and the western serviceberry 

 (Amelanchier almfolia). Outlying islands of this community are 

 found in all directions from the main area as outlined. 



The evergreen chaparral association is characteristic of the 

 southern half of California, especially near the coast, but it may be 

 found as far north as southern Oregon. There is only one important 

 deciduous dominant in this association. This is the scrub oak 

 (Quercus dumosa). The characteristic evergreen dominants are 

 chamiso (Adenostoma fasciculatum) , several species of buckthorne 

 (Ceanothus), manzanita (Arctostaphylos pungens and A. tomentosa), 

 and holly-leaved cherry (Prunus ilicifolia). This community is 

 much subject to fires and when burned the shrubs are not killed 

 below ground and usually make a rapid recovery with several new 



