THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 75 



claim to dominance, becoming a subordinate part of the conifer 

 forest, and possibly a successional stage in its development. 



In way of summary, we may say that although no extensive region 

 is completely dominated by broad-sclerophyll forest, nevertheless it 

 must be considered a climax, since it represents a degree of meso- 

 phytism between that of the chaparral and the conifer forest, and 

 because it shows plainly a tendency to gain dominance over the 

 chaparral, attainment of which is hindered only by the competition 

 of a still more mesophytic type. 



THE CLIMAX CHAPARRAL. 

 EVIDENCE OF ITS CLIMAX CHARACTER. 



The evidence of the climax nature of that type of chaparral that 

 I have designated as such is presumptive and direct. Under the 

 first head four points may be made. 



Dominance. — The very fact that the chaparral is by far the most 

 widespread of all the communities within its range (this being espe- 

 cially true in the region of its center of distribution) in itself creates 

 the presumption that the chaparral is the climax. Bearing in mind 

 that there are cases in which an important and widespread community 

 is not the climax of its region, for instance, the Pinus murrayana 

 forest of the central Rockies, whose temporary dominance is due to 

 fire, we can not accept this evidence without confirmation. 



Stability. — In most areas the chaparral has obviously been in 

 control for a long period of time — so long that there is no evidence 

 existing of previous vegetation of other type. This is not universal, 

 and in any case is not entirely conclusive. 



Occurrence on diverse sites as to soil and topography. — The fact 

 that a community is not restricted to a single topographic situation 

 or soil type, but occurs on many, is good evidence of climax nature. 

 This is true of the chaparral in the region where other evidence 

 indicates its climactic character, i. e., its center of distribution. 



Adjustment to climate. — In every region there are many plants 

 which are plainly in adjustment with some very special habitat. 

 Such are aquatic plants, halophytes, and species of rock crevices. 

 All of these occur in the chaparral region. But the species of the 

 chaparral itself possess a constant and much specialized character 

 which is plainly a response to a very particular type of climate. 

 The correspondence in area covered by climate and vegetation type 

 has already been shown. If further evidence be desired, it may 

 be derived from the ecologically equivalent "macchie" of the 

 Mediterranean region and its relation to a climate which is almost 

 identical with that of California. It is difficult to escape the con- 

 clusion that a vegetation type which is so perfectly adjusted to the 

 climate of its region must be the ultimate or climax type, in that 

 area at least where it reaches its most perfect development. 



