De I. VNER VEW D Forest Trees of the Pacific Slope

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 northwestward
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), noint 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, Pelly, 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
Iliamna to southern limit of timber at base of Alaskan Peninsula (possibly Kukak Bay).
Abundant westward on Kokbtul 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. 162°). Sea is reached again on northeastern
shore of Norton Sound at mouth of Kovuk 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. 1630). 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 690, the northern limit in Alaska. Northward on Alatna River
(tributary Koyukuk River) to point 90 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 bead.
OCCURRENCE.
On river banks, terraces, dryish margins of swamps and lakes, and up adjacent sides
of ridges and hills. 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 germination,
but with persistent vitality. Moist, decomposed organic, or mineral soils necessary