46 FOREST TREES OF THE PACIFIC SLOPE. 



at G.000 to 7,000 feet ; Middle Fork of Kaweata to Buck Canyon at 7,500 feet ; Sequoia 

 National Park, at 5,000 to 6,000 feet; Middle Fork of Kings River at mouth of Crown 

 Cnck : South Fork of Kings River, from mouth of Bubbs Creek 2 miles up, and from 

 Copper Creek 2 miles up, at 8,700 feet; Kern River canyon to point above Soda Springs; 

 South Fork of Tule River from East Tule Indian Reservation eastward. Greenhorn 

 Mountains; Piute Mountains and Mount Breckenridge at 6,000 to 7,000 feet. Tehachapi 

 Mountains on most of ridges above 6,000 feet ; noted in Tejon Canyon, south of which it 

 has not been detected. Coast ranges, abundant in Stony Creek National Forest at 3,000 

 to 6,000 feet : scarce in Sonoma County, common in Napa County, especially on Howell 

 Mountain plateau south of Angwins, but unknown on inner ranges bounding Solano and 

 Yolo counties. In San Francisco Bay region, recorded only from Mount Hamilton. 

 Santa Cruz Mountains and northward in seaward coast range to Woodside. Southern 

 Santa Lucia Mountains, at 1,000 to 5,000 feet. Santa Barbara National Forest, only 

 between Thorn Meadows and Pine Mountain Lodge, on San Rafael and Big Pine moun- 

 tains. .Mount Medulce, and in part of Alamo Mountain region, at 4,750 to 6,750 feet; 

 near .Mount Pinos ( S. 12, T. 6 N., R. 22 W.), above 5,750 feet. San Gabriel National 

 Forest, at 5,500 to 9,000 feet from head of Sheep Creek throughout Upper Swarthout 

 Valley, as well as to some of higher parts of San Gabriel and San Antonio watersheds; 

 also on Mount Wilson, Pine Flats, Brown Flats, and in Mount Gleason country. San 

 Bernardino National Forest, in Little Bear Valley to Sawpit Canyon, and less abun- 

 dantly nearly to Cleghorn Pass and Deep Creek ; usually at 4,500 or lower, to 9,000 feet, 

 but sometimes at 9,S00 on the range fronting Mohave Desert ; Santa Ana Range at about 

 1,600 feet. San Jacinto Mountains, at 3,000 to 9,000 feet; Tahquitz Valley at 6,000 to 

 9,000 feet, Onstatt and Strawberry valleys; Palomar Mountain, in Doane Valley only. 

 Farther south, noted about Julien and in San Luis Rey Canyon. 



Idaho." — Northern and central parts generally at 2,000 to 7,000 feet. Priest River 

 National Forest, at 2,000 to 4,000 feet. Coeur d'Alene Mountains, valleys, bottoms, 

 benches, and lower slopes, up to 4,900 feet. Bitterroot National Forest, slopes and flats 

 up to 7,500 feet ; also about west and south boundaries, including a deep extension into 

 the reserve near south and middle forks of Clearwater River. Thatuna Hills (near Pull- 

 man, Wash.). Sawtooth National Forest slopes and ridges at 2,500 to 5,000 feet. 



Montana. — Mainly west of Continental Divide up to 3,300 feet; Flathead Valley re- 

 gion, up to 4,125 feet. Valley of North Fork of Flathead River, between Indian and 

 Logging cricks, and Kootenai Valley (small areas). Bitterroot Valley up to 5,800 feet. 

 Northern part of State, but not on east side of Continental Divide, nor on Whitefish 

 Mountains. Farther south, east of Divide, sparingly on Little Belt Mountains between 

 6,000 and 6,500 feet; in Elkhorn Mountains at 4,000 to 5,500 feet, and in Absaroka 

 Division of Yellowstone National Forest at 5,500 to 6,000 feet. 



The pine occurring mainly cast of the Rockies and throughout the region 

 southward to Texas and Arizona is Pinus ponderosa scopulorum, the detailed 

 range <>f which will be dealt with in a later bulletin. 



OCCURRENCE. 



On dry and moist slopes, on tops of ridges, and in canyon bottoms. Very moderate in 

 soil requirements. Grows on all soils from glacial drift and volcanic ash to deep, loose 

 sands and stiff clays; dry, well-drained sandy or gravelly soils most characteristic. Re- 

 quires very little soil moisture; its enormously deep roots enable it to thrive in soils 

 nearly as dry as those in which pifion pines and junipers grow. 



Occurs in pure extensive stands and in mixture with other conifers and broadleaf 

 trees. Pure large, but interrupted, forests are found on east slopes and foothills of the 

 Cascades in Washington and Oregon; open, grassy park lands intervene; little or no un- 

 derbrusb or even grass occurs in these forests, on account of continued fires. Occasionally 

 with western larch and Douglas fir. In Sierras, in scattered smaller pure stands, or, 

 moic often, variously mixed with sugar pine, incense cedar, Douglas fir, white fir, and 

 smaller numbers of California red fir. Often associated with Kellogg oak, occasionally 

 with bigtrees, and at lower elevations sparsely mingled with gray pine. Mixed forests 

 usually with brushy ground cover and considerable young growth. 



Climatic Conditions. — Great seasonal and daily variations of temperature are en- 

 dured. Seasonal range between about 28° and 110° F. Mean annual rainfall in region 

 of principal occurrence from 10 to 50 inches; an annual rainfall of less than 20 inches 

 probably limits its occurrence in commercial quantities. 



" The north Rocky Mountain range of this tree is given in order to complete the dis- 

 tribution of what must be regarded as the ordinary form of western yellow pine. South- 

 ward and eastward it passes imperceptibly into P. ponderosa scopulorum. 



