90 FOREST TREES OF THE PACIFIC SLOPE. 



Western Canada. — Crosses Continental Divide at Liard River, reaching interior 

 plateau and extending westward to eastern slopes of Pacific coast ranges and northwest- 

 ward into Alaska ; southern limit now known is Stikine River, and seaward limits in Coast 

 Ranges are Upper Stikine and Taku rivers. Shallow Lake (north of White Pass, at 

 about 2,400 feet), point near Divide at head of Chilkat River (at about 2,600 feet), 

 and point at timberline (about 4,500 feet) on north side of St. Elias Range. Common 

 on rivers, islands, in sheltered valleys, hillsides, sometimes to tops of plateau (at 3,000 

 to 4,000 feet) ; in valleys of Dease Lake and River, and of Frances, Upper Liard, Yukon, 

 Klondike, McQuestion, Felly, and White rivers. 



Alaska. — Southward to Alaska Range, and on north slopes up to 3,500 or 4,000 feet 

 elevation, but on south slopes, to 1,200 feet. Probably farther southward between 

 Alaska Range and coast in valleys of Upper Sushitna and Copper rivers, reaching Pacific 

 side of Coast Range only at Cook Inlet (long. 150°) ; thence extending from shores 

 of Turnagain Arm up lower Sushitna River, on west side of Kenai Mountains, to Kenai 

 Lake (alt. 2,000 feet) ; southward on west shore of Cook Inlet, about Lakes Clark and 

 lliamna to southern limit of timber at base of Alaskan Peninsula (possibly Kukak Bay). 

 Abundant westward on Kokhtul and Mulchatna rivers, extending to mouths of Nushagak 

 and Aleknagik rivers at Bristol Bay. Western limit of range is on Kuskokwim and 

 Yukon rivers, near head of their deltas (long. 1(32°). Sea is reached again on north- 

 eastern shore of Norton Sound at mouth of Koyuk River, in Norton Bay, and at mouth 

 of Niukluk River, in Golofnin Bay, but limit turns eastward in northern part of Seward 

 Peninsula, including only head of Buckland River, and not entering Selawik River basin. 

 Northward white spruce reappears throughout Kobuk River Basin, reaching sea on 

 Kotzebue Sound, and reappearing still farther north on middle course of Noatuk River, 

 here reaching its western and northern limit on- west coast of Alaska (in about lat. 68°, 

 long. 163°). Extends eastward along southern slope of Endicott Range, between Yukon 

 River Valley and Arctic Slope, on Koyukuk River and its tributaries, to about latitude 

 67°, toward the international boundary, and farther northward on Porcupine River 

 and its tributaries, to about latitude 68° ; reappears in Turner River Basin, on Arctic 

 Slope, to about latitude 69°, the northern limit in Alaska. Northward on Alatna River 

 (tributary Koyukuk River) to point 00 miles from mouth; northward on John River 

 (tributary Koyukuk) at about 2,500 feet elevation, to point 25 miles south of pass at 

 head, and in valley of Chandlar River to head. 



OCCURRENCE. 



On river banks, terraces, dryish margins of swamps and lakes, and up adjacent sides 

 of ridges and bills. Most frequent on sandy loam soils with moderate moisture, but 

 grows on very shallow soils from margins of swamps to tops of mountains. Largest in 

 moist, well-drained, finely divided porous soil ; soils too dry or too wet produce dwarfed, 

 slow growth. Forms pure, dense forests of large and limited extent and occurs in mixed 

 stands. 



The principal timber tree in Yukon drainage, occurring in dense groves and belts on 

 alluvial flats and on islands, but in more open stands away from the river. Toward 

 north limit in Alaska, more and more dwarfed, small clumps growing commonly in 

 gulches. Dominant tree in Kenai Peninsula of Alaska on drier situations, but replaced 

 by black spruce in swamps; in such localities always very scrubby. In north British 

 Columbia generally forming extensive pure forests on rivers and lower valley slopes ; it 

 often gives way to black spruce, tamarack, or cottonwoods on flats and to lodgepole pine 

 on dry terraces ; at timberline, on inland mountains of north Canada, sometimes with 

 alpine fir. Often in dense, pure groves and strips of forest ; closely associated with 

 birch, red alder, aspen, willows, and near streams with black cotton wood. On Kenai 

 Peninsula, with black hemlock, balm-of-Gilead, aspen, and western birches. Toward 

 north limit in Alaska, more and more subordinate to poplars, here single trees and small 

 clumps being scattered among birch and poplar. 



Climatic Conditions. — With much the same range as black spruce, white spruce 

 endures practically the same severe features of climate. 



Tolerance. — Tolerant of considerable shade, young trees maintaining a slow growth 

 for many years under heavy crown cover. Marked in recovery from suppression, being 

 surpassed in this only by black and red spruces. Retains side branches persistently ; 

 long, clear stems occur only in close stands. Thriving under light shade of poplars and 

 birches, it often replaces these after fire or lumbering. 



Reproduction. — Moderately prolific seeder ; considerable seed produced locally every 

 year, while heavy seed production occurs at more or less regular, but long, intervals over 

 parts of range. In New England, periods between seed years about eight years ; seeding 

 habits in Northwest not determined. Seed with only moderately high rate of germina- 

 tion, but with persistent vitality. Moist, decomposed organic, or mineral soils necessary 



