282 THE S TUDY OF PLANT COMMUNITIES * Chapter X 



Chaparral- -This community extends its dominance over a wide 

 area and a diversity of habitats, and its composition is proportion- 

 ately diverse. It includes at least forty species of evergreen shrubs 

 with varying degrees of dominance and importance, which may 

 occur in many combinations but which invariably form low, dense 



FIG. 148. Chaparral in the Santa Lucia Mountains, Calif. Smooth cover at 

 top, mostly Adenostoma. Light-colored shrubs in shallow ravine at left, Arc- 

 tostaphylos glauca. Grades into broad sclerophyll forest in deep ravine at 

 right.— Photo by W. S. Cooper. 



thickets. The most important and constant species is chamiso 

 (Adenostoma jasciciilatnm). The numerous species of manzanita 

 (Arctostaphylos) are scarcely less characteristic, and of these A. 

 tomentosa is the widest ranging. Others with high constancy are 

 Heteromeles arbutifolia, Ceanothus cimeatus (9 other spp.), Quer- 

 cus dumosa, and Cercocarpus betulaejormis. 



Fires.— The long, dry summers and the nature of sclerophyllous 

 vegetation make frequent fires the rule. A study in the Santa 

 Monica mountains showed that chaparral stems were mostly about 

 twenty-five years of age, and a stand without fire for fifty years 

 was considered old. An ordinary fire causes chaparral to sprout 

 profusely, and then, come back to normal within ten years. 12 Fire 

 usually favors the extension of chaparral at the expense of sclero- 

 phyll forest. Too frequent fires, however, may cause the death of 

 chaparral and its replacement by grassland. Undoubtedly, the orig- 



