72 THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



V. DEVELOPMENT. 



THE CLIMAX REGIONS OF CALIFORNIA. 



In a region of slight relief and uniform climate, such as the Missis- 

 sippi Basin or the Great Plains, a single climax extends for hundreds 

 or even thousands of miles. In California the case is very different. 

 The extremes of latitude and altitude, the proximity of the ocean, 

 and the barrier influence of high mountains upon moisture-bearing 

 winds all operate to bring about great and abrupt climatic differences, 

 and therefore great vegetational complexity. Instead of a single 

 climax community there are a half dozen, each, though limited in 

 area, comparable to such a community as the Great Plains grassland 

 or the eastern deciduous forest. Successional investigation has not 

 proceeded far enough to enable us to define these climaxes with 

 accuracy. The following outline is tentative, and is given merely 

 that we may properly place the communities with which we are 

 dealing. 



The conifer-forest climaxes are three in number, and the first two 

 have important contact relations with the broad-sclerophyll com- 

 munities. The Pacific Conifer Climax Formation, which includes 

 the forests of the coastal region from California to Alaska, is repre- 

 sented in northwestern CaUfornia by two associations: (1) The 

 Sequoia sempervirens association ranges from the northern boundary 

 of the State, in the immediate vicinity of the coast, southward to 

 San Luis Obispo County. South of San Francisco Bay its continuity 

 is much broken. (2) The Pseudotsuga association, which has its 

 center in the Puget Sound region, is poorly represented in California, 

 occurring in the interior of the north Coast Ranges. It is confused 

 with other communities, especially the broad-sclerophyll forest, 

 so that the portion included within the State should probably be 

 considered as transitional. 



The Montane Conifer Climax Formation covers the middle altitudes 

 of the interior mountain region of western America, and the character 

 tree everywhere is Pinus ponderosa. In California it is represented 

 by the Pinus ponder osa-lamhertiana association, which occurs in the 

 middle altitudes of the west slope of the Sierras and on the higher 

 Coast Ranges and the mountains of southern California. 



The Subalpine Conifer Climax Formation is practically coextensive 

 with the preceding in general range, but lies above it altitudinally. 

 I will not apply a designation to the California subdivision, as it is 

 rather complex, and no successional work has been done within it. 

 It occurs in the higher Sierras and there are isolated outliers else- 

 where. The character trees are Abies magnifica and Pinus monticola 

 in the lower part, and Pinu^ alhicaulis and Tsuga mertensiana near 

 timberline. 



