9<± FOREST TREES OF THE PACIFIC SLOPE. 



Mountains (from northern Idaho), stretching northward to Canadian Pacific Railway 

 line (possibly farther), reaching 5,000 feet on west slope of Selkirk; while on east side, 

 which it ascends to summit, its first abundant appearance is on Beaver Creek, at 3,500 

 feet. Eastern limit is Donald, on Columbia River, at 2,586 feet. 



Washington. — Throughout western part, except on high summits, and generally extend- 

 ing from sea level to 4,000 or 5,000 feet elevation ; westward to east slopes of Cascades ; 

 more abundant on west side middle slopes of Cascade and of coast ranges than on coast 

 or in depression between these ranges. Mountains of northern Washington and east- 

 ward to Idaho, but not in Blue Mountains (southeastern Washington). Washington 

 National Forest, common over west slopes of Cascades on benches and mountain sides, 

 up to 4,000 or 5,000 feet ; on east slopes only in moist valleys, at 2,100 to 4,700 feet 

 elevation on Stehekin River, Agnes, and Early Winter creeks, on headwaters of Entiat 

 and Wenache rivers, throughout upper Yakima and Chealum valleys and eastward to 

 Chealum Lake. Mount Rainier National Forest, abundant on west slopes up to 5,000 

 feet, but scarce on east slope on Tannum Lake and on head of Klickitat River. Abun- 

 dant in Olympic Mountains up to 4,500 feet elevation. 



Oregon. — Throughout western part, up to about 5,500 feet, and down to sea-level on 

 coast, but not on borders of Columbia River where it crosses Cascades nor in Willam- 

 ette River Valley below 1,500 feet ; extends southward in Cascades to Lake of the Woods 

 (T. 38 S., R. 6 E.) and on Coast Range to California. Cascade National Forest 

 (North), abundant west of range, at 1,600 to 4,800 feet, but on east side confined to 

 headwaters of rivers and occurs only for a short distance south of Mount Hood to Bea- 

 ver Creek and Warm Springs River i T. 6 S., R. 9 E.) ; south side of Mount Hood, up to 

 Government Camp, at 3,600 feet, and north side from 3,500 feet northward to point 22 

 miles from Columbia River. Farther south in Cascades, scattered over west side only, 

 south of Mount Thielson, occurring at elevations of 5,200 to 6,000 feet only on north 

 and south slopes of Umpqua-Rogue River Divide, Huckleberry Mountain, headwaters of 

 Rogue River and Big Butte Creek, Mount Pitt, about Lake of the Woods, and sparingly 

 on mountain sides and flats eastward to east side of divide south of the lake. Not de- 

 tected in the Siskiyous. 



California. — In fog belt on west side of Coast Range, and southward to between Elk 

 and Alder creeks (Mendocino County), reappearing farther south sparingly in Marin 

 County : approaches to within one-half mile of coast in Del Norte County, at Crescent 

 City and other points ; eastward in Humboldt County to ridge east of Redwood Creek, 

 at 3,200 feet ; but is farther from coast in Mendocino County, where it extends inland 

 about 20 miles, and at Mendocino, about 10 miles inland ; generally on steep slopes of 

 canyons and tops of ridges up to about 2,000 feet. 



OCCURRENCE. 



A tree of the middle, moist forest zone, from sea level to 7,000 feet elevation. 

 More abundant on west mountain slopes than on east slopes, and avoiding dry in- 

 land basins of Oregon, Washington, and British Columbia, but reappearing on west slope of 

 Rocky Mountains. Largest growth on lower slopes, flats, stream bottoms, etc., on west 

 slope of Cascades and coast ranges of Washington and British Columbia. At higher eleva- 

 tions at South in Washington, Oregon, and California than toward its north limit in 

 Alaska ; likewise, at lower elevations on coast mountains than in Cascades and on west 

 slope of Rockies. With abundant atmospheric and soil moisture, it thrives on poor, thin 

 soils and on any exposure, but best on deep, porous, moist soils. Soil and exposure 

 become much more important with decrease in moisture. Lack of soil and moisture pro- 

 duce stunted growth, as do also high elevations, even with abundant moisture and good 

 soils. In dryish poor soils, it seeks chiefly cooler, north situations. 



Usually subordinate in association with other trees, but often dominating, especially 

 in Alaska, where occasional pure stands also occur. Generally scattered in patches, 

 groups, or singly through the forest. In Alaska, with Sitka spruce, western red cedar, 

 and black hemlock, and usually dominant. In Vancouver Island, British Columbia, Wash- 

 ington, and Oregon, chiefly with western red cedar, yellow cedar, Sitka spruce, lowland 

 fir, amabilis fir, yew, Douglas fir, western white pine, and lodgepole pine ; while in north 

 California it occurs with redwood. Its general and common associates are Douglas fir, 

 western red cedar, and lowland fir, from the coast to the Rocky Mountains. Broadleaf 

 and vine maples, black cottonwood, and red alder occur with it also at low elevations. 



Climatic Conditions. — Climate of range, in general, favorable for tree growth, being 

 comparatively mild and uniform, with gradual changes of temperature, which is not 

 extreme. Precipitation generally heavy and humidity high. However, average annual 

 precipitation, humidity, and range of temperature vary considerably from California 

 to Alaska and from Pacific to Rocky Mountains, and from sea level to limit of eleva- 

 tion (7,000 feet). Average annual precipitation, from about 20 inches in California and 



