276 FOREST TREES OF THE PACIFIC SLOPE. 



Nevada, in the yellow pine belt, at elevations of from 0,000 to 7,500 feet, and also oppo- 

 site Lone Pine, at 9,000 to 9,500 feet ; probably occurs at many other points on this 

 slope. Abundant in northern coast ranges, especially near coast. Frequent about San 

 Francisco Bay, as on Mount Tamalpais, Oakland Hills, and Mount St. Helena; as also 

 on seaward range south of San Francisco, in Santa Cruz Mountains, and at Monterey 

 on north side of Huckleberry Hill. Probably also in Mount Hamilton Range. Rather 

 scarce in Santa Lucia. San Luis Obispo, Santa Barbara, and San Gabriel National for- 

 ests, but frequent in San Bernardino National Forest, where it forms an important part 

 of chaparral at 8,500 to 10,000 feet elevation, while in San Jacinto National Forest it 

 grows at from 8,000 to 10,800 feet. 



OCCURRENCE. 



Mountain slopes, sheltered ravines and valleys, slopes of canyons and gulches ; in 

 rather dry or extremely dry rocky and gravelly soils. Largest in valleys of northwest 

 California ; small or shrubby at high levels elsewhere. 



In dense pure-growth thickets over large areas in latter regions, interspersed with 

 low forms of canyon live oak, western juniper, scrubby Jeffrey pine, scrub oak and cha- 

 parral ; but often scattered among redwood and Douglas fir. 



Climatic Conditions. — Combine those of white fir and Jeffrey pine (at high levels) 

 and of Douglas fir and redwood (at lower levels). 



Tolerance. — Very tolerant of shade ; in later life endures side shade but requires 

 overhead light for best height growth, clearing its long trunks well in close stands. 



Reproduction. — Abundant seeder, but less §o in mixed stands, where seedlings are only 

 fairly frequent ; more plentiful at higher levels, where washing covers seed in crevices and 

 pockets in shade of seedlings and other plants. Much seed eaten by rodents. 



QTJERCUS. OAKS. 



The oaks form a large group, composed almost entirely of trees, some of 

 which are the most important timber trees of North America. They are world- 

 famous trees, which through their powerfully built trunks, branches, and roots, 

 have earned the reputation of the greatest physical sturdiness. The great 

 strength and other useful commercial qualities of their woods, together with 

 the fact that many of the species occur over large areas in nearly pure forests, 

 render these trees of the highest economic value. Most of them are long-lived 

 and very aggressive in their persistent efforts to maintain themselves, through 

 seed and sprout reproduction, against fire and the ax. and against other forest 

 trees and to extend their domain. With some exceptions they grow rather 

 slowly and require several centuries to produce the high-class saw timber 

 which our virgin oak forests once furnished in great quantities, but which now 

 is rapidly disappearing. They are cosmopolitan, and adapt themselves to dry, 

 sterile soils, as well as to moist, fertile ones, and to cold as well as to temperate 

 and tropical climates. They prefer, however, temperate regions, in which the 

 number of species is greatest. In altitudinal range they are equally unre- 

 stricted, for they push their sturdy ranks from near the sea far up mountain 

 slopes and canyons to nearly 10,000 feet elevation. 



The two broad classes of our oaks — the white oaks and the black oaks — are 

 popularly distinguished by the color of the wood and bark. Technically they 

 are based upon different habits of producing fruit (acorns). The white oaks 

 produce their acorns in one season ; the black oaks produce theirs in two 

 seasons. There are four exceptions which do not fit these classifications, 

 namely, two Pacific oaks, which have wood resembling that of white oaks but 

 which require two seasons to mature their acorns, and one Atlantic and one 

 Pacific oak which have the darker wood and bark of black oaks but which 

 mature their acorns in one season. 



Many oaks have massive and straight trunks: most of them have furrowed 

 and scaly bark and particularly large, powerful branches which often form im- 



