CLIMAX COMMUNITIES : PRESENT DISTRIBUTION 



281 



tropical with long, dry summers and heavy winter rainfall. Total 

 precipitation is not less than ten or more than thirty inches, and, 

 of this amount, no more than 20 percent falls in summer. In this 

 area, desert vegetation appears where precipitation is less than ten 

 inches, and, if it is over thirty inches, conifer forest is dominant. 72 

 The two climaxes may be found in alternating patches in almost 

 any part of their more or less coinciding ranges. However, chap- 

 arral occupies the greatest area and is climax in the south where it 



Fig. 147. Broad sclerophyll forest (Quercus agrifolia, Arubutus, etc.) on 

 north-facing slope (foreground and right). Chaparral on south-facing slope 

 (left). Santa Lucia Mountains, Calif.— Photo by W. S. Cooper. 



grades into desert, and sclerophyll forest is climax in the north and 

 at the margin of montane conifer forest where its variations may 

 be a part of the woodland zone. Where found together, the two 

 communities bear no successional relationship to each other. The 

 forest consistently appears on north slopes and the better sites, 

 chaparral on south slopes and drier sites. The forest is postclimax 

 in the south, and chaparral is preclimax in the north. 



Sclerophyll Forest— The important evergreen forest trees are 

 Quercus agrifolia, Q. chrysolepis, Q. ivislizeni, Lithocarpus densi- 

 flora, Umbellularia californica, Arbutus menziesii, Castanopsis 

 chrysophylla, and Myrica californica. Several deciduous trees are 

 almost as characteristic, as are a number of shrub and herb associ- 

 ates. The dominants may occur in various combinations related to 

 altitude and exposure. 



