THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 7 



A few of the Californian sclerophylls, too, extend far beyond the 

 average limits of the type. Ardostaphylos pungens ranges eastward 

 to southwestern Colorado, where it forms an unimportant part of 

 the deciduous thickets. Moreover, Quercus undulata, an important 

 member of the Rocky Mountain thickets, itself tends strongly 

 toward evergreenness. 



The chaparral. — The chaparral may be defined as a scrub com- 

 munity, dominated by many species belonging to genera unrelated 

 taxonomically, but of a single constant ecological type, the most 

 important features of which are the root system, extensive in pro- 

 portion to the size of the plant, the dense rigid branching, and pre- 

 eminently the leaf, which is small, thick, heavily cutinized, and 

 evergreen. y This definition might be applied with equal accuracy 

 to the macchie of the Mediterranean regions; chaparral and macchie 

 appear to be ecologically equivalent. The chaparral is characteris- 

 tically, almost exclusively, of California west of the Sierra crest and 

 the deserts; in other words, of the region of "Californian" climate. 



Because of its ecological distinctness, the Californian broad- 

 sclerophyll scrub is entitled to a name of its own, and the term 

 "chaparral," by reason of almost universal usage, is the obvious 

 choice. The desert scrub and the deciduous thicket, which have 

 been called chaparral by various authors, can easily be provided 

 with other names if the ones used here are not satisfactory. Finally, 

 it should be emphasized that the chaparral finds its closest ecological 

 relative not in any other scrub community, but in the broad-sclero- 

 phyll forest, which is a response to the same type of climate. 



PREVIOUS WORK. 



Practically no work of purely ecological nature dealing with the 

 chaparral has been published up to the present time. Several 

 foresters have written excellent accounts of the aspect and behavior 

 of the brush, especially in its relation to the forests which are asso- 

 ciated with it. This emphasis is natural, since the chaparral is 

 extremely important to the forester whose field of work is in Cali- 

 fornia. It is essential for him to determine whether the brush can 

 be replaced by a more valuable crop and, if not, how it can best be 

 made to perform its important economic function of water-shed 

 protection. In addition, there have been taxonomic studies of 

 certain genera, and phytogeographic researches of more or less 

 general nature, in which the chaparral has been treated. The 

 broad-sclerophyll forest has been almost wholly neglected, except in 

 its taxonomic aspects. It will be convenient to arrange the following 

 brief survey of the literature under four heads, adding a miscellaneous 

 group for certain papers that can not be classified under the three 

 mentioned above. 



(a) Detailed notices of taxonomic researches are outside the 



