THE BROAD-SCLEROPHYLL VEGETATION OF CALIFORNIA. 



By William S. Cooper. 



INTRODUCTION. 



The characteristic vegetation of California west of the high 

 Sierra Nevada and the Colorado and Mojave Deserts is of the type 

 aptly described by the term "broad-sclerophyll." The use of the 

 prefix "broad," which expresses a very general group character, 

 in distinction to the needle-leaf of the "narrow-sclerophyll" conifers, 

 is not without its disadvantages, since the most important chaparral 

 species, Adenostoma fasciculatum, possesses a needle-like leaf. This 

 single though important exception seems not to be sufficient cause 

 for discarding the very expressive appellation. 



Broad-sclerophyll vegetation is not confined to California, but 

 recurs upon other portions of the earth's surface, notably the shores 

 of the Mediterranean. The leaf character is the conspicuous and 

 diagnostic feature, that organ being thick, stiff, and hard, ordinarily 

 flat, and evergreen. Schimper (80) has shown that this vegetation 

 type is everywhere correlated with a definite type of climate, namely, 

 one with a long, dry summer and a rainy winter. Some of the broad- 

 sclerophylls are trees, but most are scrubs. We therefore find 

 broad-sclerophyll forest and broad-sclerophyll scrub, the latter 

 being the more widespread and important. The present work is 

 an ecological study of the broad-sclerophylls of California; of their 

 relations to climate and soil and to each other. Being somewhat 

 of a pioneer work, many phases of the problem are touched, and 

 many lines of investigation have been opened up which could not 

 be followed to the end. The field is a fascinating one, and a lifetime 

 would not suffice to exhaust its possibilities. 



In the Mediterranean region broad-sclerophyll scrub is known as 

 "macchie" and "garigue"; in California it is called "chaparral." It 

 has already been noted that the scrub is more important than the forest, 

 both scientifically and economically. In fact, the present research 

 began as an investigation of the chaparral alone. Because of the close 

 relations between them, it was a simple matter to extend the field of 

 study to include the trees. The term "chaparral" is of Spanish origin, 

 being derived from the word "chaparra," meaning scrub oak. It 

 seems to have been applied by the early explorers of California to 

 the low, shrubby, dominantly evergreen vegetation which they found 

 to be so characteristic of the Coast Ranges and the foothills of the 

 Sierras. Locally the term is sometimes restricted to a single species, 

 often Ceanothus cuneatus. The term ' ' chamisal ' ' is frequently applied 

 to a pure growth of Adenostoma fasciculatum or "chamise." 



