Picea glauca

''Picea glauca'', the white spruce, is a species of spruce native to the northern temperate and boreal forests in North America. ''Picea glauca'' is native from central Alaska all through the east, across southern/central Canada to the Avalon Peninsula in Newfoundland, and south to Montana, Minnesota, Wisconsin, Michigan, Upstate New York and Vermont, along with the mountainous and immediate coastal portions of New Hampshire and Maine, where temperatures are just barely cool and moist enough to support it. There is also an isolated population in the Black Hills of South Dakota and Wyoming. It is also known as Canadian spruce, skunk spruce, cat spruce, Black Hills spruce, western white spruce, Alberta white spruce, and Porsild spruce.

Description

The white spruce is a large evergreen conifer which normally grows to tall, but can grow up to tall with a trunk diameter of up to . The bark is thin and scaly, flaking off in small circular plates across. The crown is narrowconical in young trees, becoming cylindrical in older trees. The shoots are pale buff-brown, glabrous in the east of the range, but often pubescent in the west, and with prominent pulvini. The leaves are needle-like, 12 to 20 millimetres long, rhombic in cross-section, glaucous blue-green above (hence ''glauca'') with several thin lines of stomata, and blue-white below with two broad bands of stomata.

The cones are pendulous, slender, cylindrical, 3 to 7 cm long and 1.5 cm wide when closed, opening to 2.5 cm broad. They have thin, flexible scales 15  mm long with a smoothly rounded margin. They are green or reddish, maturing to pale brown 4 to 8 months after pollination. The seeds are black, 2 to 3 mm long, with a slender, 5 to 8 mm long pale brown wing.

File:Picea glauca sapling Kluane NP.jpg, Young tree
File:2009-05-13 EPB mature (02) DDumais.jpg, Mature tree
File:P1260709 DDumais.jpg, Mature tree that has lost its lower branches
File:Picea glauca-bark.jpg, The bark is thin and scaly, flaking off in small circular plates
File:Picea glauca twig Denali NP AK.jpg, Twig with striped, blue-green, four-sided needles
File:Picea glauca Świerk biały 2011-09-11 03.jpg, Mature female cone
File:Picea glauca Brno3.JPG, Female cone
File:Picea glauca young female cone - Keila.jpg, Young female cone
File:Picea glauca 2.jpg, Male cone and pollen

Seeds

Seeds are small, 2.5 to 5 mm long, oblong, and acute at the base. Determinations of the average number of sound seeds per white spruce cone have ranged from 32 to 130.Zasada, J.C.; Viereck, L.A. 1970. White spruce cone and seed production in interior Alaska, 1957–68. USDA, For. Serv., Pacific NW For. Range Exp. Sta., Portland OR, Res. Note PNW-129. 11 p. oates et al. 1994/ref>

Common causes of empty seed are lack of pollination, abortion of the ovule, and insect damage.

The average weight per individual seed varies from 1.1 mg to 3.2 mg.

Each seed is clasped by a thin wing 2 to 4 times as long as the seed. Seed and wing are appressed to the cone scale. Embryo and megagametophyte are soft and translucent at first; later the endosperm becomes firm and milky white, while the embryo becomes cream-coloured or light yellow. At maturity, the testa darkens rapidly from light brown to dark brown or black.Crossley, D.I. 1953. Seed maturity in white spruce. Canada Dep. Resour. and Devel., For. Branch, For. Res. Div., Ottawa ON, Silv. Res. Note 104. 16 p. Mature seeds “snaps in two” when cut by a sharp knife on a firm surface.

White spruce cones reach their maximum size after 800 GDD. Cone moisture content decreases gradually after about 1000 GDD.Cram, W.H.; Worden, H.A. 1957. Maturity of white spruce cones and seed. For. Sci. 3:263–269.

Cone colour also can be used to help determine the degree of maturation, but cones may be red, pink or green.Teich, A.H. 1970. Genetic control of female flower colour and random mating in white spruce. Can. Dep. Fish. For., Can. For. Serv., Ottawa ON, Bi-mo. Res. Notes 26:2. Collection and storage dates and conditions influence germination requirements and early seedling growth.Zasada, J.C. 1973. Effect of cone storage method and collection date on Alaskan white spruce (''Picea glauca'') seed quality. p. 1–10 (paper 19) ''in'' Proc. Seed Problems. IUFRO Symp. Seed Processing, Bergen, Norway. Working Party S2.01, Royal Coll. For., Bergen, Norway, Vol. 1. oates et al. 1994/ref>Edwards, I.K. 1977. Fertility of transplant fields at the Prince Albert Forest Nursery. Can. Dep. Fish. Environ., Can. For. Serv., Northern For. Res. Centre, Edmonton AB, Inf. Rep. NOR-X-189. 21 p.Winston, D.A.; Haddon, B.D. 1981. Effects of early cone collection and artificial ripening on white spruce and red pine germination. Can. J. For. Res. 11:817–826.

A bushel (35 L) of cones, which may contain 6500 to 8000 cones, yields of clean seed.USDA Forest Service. 1948. Woody-plant Seed Manual. USDA, For. Serv., Washington DC, Misc. Publ. 654. 416 p.

Seed dispersal begins after cone scales reflex with cone maturation in the late summer or early fall of the year of formation. Cones open at moisture contents of 45% to 70% and specific gravities of 0.6 to 0.8. Weather affects both the initiation and pattern of seed dispersal, but cone opening and the pattern of seed dispersal can vary among trees in the same stand. Even after dispersal has begun, cold, damp weather will cause cone scales to close; they will reopen during dry weather. Most seed falls early rather than late, but dispersal may continue through fall and winter and even into the next growing season.Zasada, J. 1986. Natural regeneration of trees and tall shrubs on forest sites in interior Alaska. p. 44–73'' in'' Van Cleve, K.; Chapin, F.S.; Flanagan, P.W.; Viereck, L.A.; Dyrness, C.T. (Eds.). Forest Ecosystems in the Alaskan Taiga: a Synthesis of Structure and Function. Springer-Verlag New York NY.Rowe, J.S. 1953. Viable seed on white spruce trees in midsummer. Can. Dep. Northern Affairs and National Resources, For. Branch, For. Res. Div., Ottawa ON, Silv. Leafl. 99. 2 p. Seed dispersal occurs mainly in late summer or early fall.

White spruce seed is initially dispersed through the air by wind. Both the initiation and pattern of seed dispersal depend on the weather, but these can vary among trees in the same stand. Small amounts of white spruce seed are normally dispersed beyond 100 m from the seed source, but exceptionally seeds have been found more than 300–400 m from the nearest seed source.

Root system

The root system of white spruce is highly variable and adaptable, responding to a variety of edaphic factors, especially soil moisture, soil fertility, and mechanical impedance.Wagg, J.W.G. 1964. White spruce regeneration on the Peace and Slave River lowlands. Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1069. 35 p.Wagg, J.W.B. 1967. Origin and development of white spruce root-forms. Can. Dep. For. Rural Devel., For. Branch, Ottawa ON, Publ. 1192. 45 p. On soils that limit rooting depth, the root system is plate-like, but it is a common misconception to assume that white spruce is genetically constrained to develop plate-like root systems irrespective of soil conditions.Sutton, R.F. 1969. Form and development of conifer root systems. Commonw. For. Bureau, Oxford, U.K., Tech. Communication No. 7. 131 p. In the nursery, or naturally in the forest, white spruce usually develops several long 'running' roots just below the ground surface.Mullin, R.E. 1957. Experiments with root and top pruning of white spruce nursery stock. Ont. Dep. Lands For., Res. Div., Toronto ON, Res. Rep. 36. 31 p.

The structure of the tracheids in the long lateral roots of white spruce varies with soil nitrogen availability.Krasowski, M.J.; Owens, J.N. 1999. Tracheids in white spruce seedling’s long lateral roots in response to nitrogen availability. Plant and Soil 217(1/2):215–228.

Stem

White spruce can live for several hundred years, with an estimated average lifespan of 250 to 300 years.Dallimore, W.; Jackson, A.B. 1961. A Handbook of Coniferae including Ginkgoaceae, 3rd (1948) ed. reprinted with corrections. Arnold, London, U.K. 686 p.

Slow-growing trees in rigorous climates are also capable of great longevity. White spruce high on the shore of Urquhart Lake, Northwest Territories, were found to be more than 300 years old.Hare, F.K.; Ritchie, J. 1972. The boreal bioclimates. Geogr. Rev. 62:333–365.

Bark

The bark of mature white spruce is scaly or flaky, grey-brown or ash-brown, but silvery when freshly exposed.Brayshaw, T.C. 1960. Key to the native trees of Canada. Canada Dep. For., Bull. 125. 43 p.Harlow, W.M.; Harrar, E.S. 1950. Textbook of Dendrology, 3rd ed. McGraw-Hill, New York NY. 555 p. Resin blisters are normally lacking, but the Porsild spruce ''Picea glauca'' var. ''porsildii'' Raup has been credited with having smooth resin-blistered bark.Hosie, R.C. 1969. Native Trees of Canada, 7th ed. Can. Dep. Fish. For., Can. For. Serv., Ottawa ON. 380 p.

White spruce bark is mostly less than 8 mm and not more than 9.5 mm thick.Hale, J.D. 1955. Thickness and density of bark. Pulp and Paper Mag. Canada, Dec.:3–7.Chang, Y.P. 1954. Bark structure of North American conifers. USDA, For. Serv., Tech. Bull. 1095. 86 p.

Chemistry

Isorhapontin can be found in spruce species such as the white spruce.

Distribution

White spruce has a transcontinental range in North America. In Canada, its contiguous distribution encompasses virtually the whole of the Boreal, Subalpine, Montane, Columbia, Great Lakes–St. Lawrence, and Acadian Forest Regions, extending into every province and territory.Rowe, J.S 1972. Forest regions of Canada. Can. Dep. Environ., Can. For. Serv., Ottawa ON, Publ. 1300. 172 p.Forestry Branch. 1961. Native Trees of Canada, 6th ed. Canada Dep. Northern Affairs and National Resour., For. Branch, Ottawa ON, Bull. 61. 291 p. On the west coast of Hudson Bay, it extends to Seal River, about 59°N, "from which the northward limit runs apparently almost directly north-west to near the mouth of the Mackenzie River, or about latitude 68°".Bell, R. 1881. The northern limits of the principal forest trees of Canada east of the Rocky Mountains. p.38c–56c ''in'' Geological and Natural History Survey of Canada, Ottawa ON, Report 1879/1880. Collins and SumnerCollins, G.L.; Sumner, L. 1953. Northeast Arctic: the last great wilderness. Sierra Club Bull. 38:13–26. reported finding white spruce within 13 km of the Arctic coast in the Firth Valley, Yukon, at about 69°30′ N, 139°30′ W. It reaches within 100 km of the Pacific Ocean in the Skeena Valley, overlapping with the range of Sitka spruce (''Picea sitchensis''), and almost reaching the Arctic Ocean at latitude 69° N in the District of Mackenzie, with white spruce up to 15 m high occurring on some of the islands in the Delta near Inuvik. The wide variety of ecological conditions in which 4 Quebec conifers, including white spruce, are able to establish themselves, was noted by Lafond,Lafond, A. 1966. Notes sur l’écologie de quatre conifères du Québec: ''Picea mariana, P. glauca, Abies balsamea'', et ''Pinus banksiana''. Naturaliste Canadien, Québec 93:823–842. but white spruce was more exacting than black spruce. In the United States, the range of white spruce extends into Maine, Vermont, New Hampshire, New York, Michigan, Wisconsin, Minnesota, and Alaska,Sargent, C.S. 1922. Manual of the Trees of North America, 2nd corrected ed. Houghton and Mifflin, Boston, 510 p., reprinted 1961 in 2 volumes, Dover Publications, New York NY, Vol. 1. 433 p. 3999 bib gives 910 p./ref> where it reaches the Bering Strait in 66°44′ N" at Norton Bay and the Gulf of Alaska at Cook Inlet.

Southern outliers have been reported in southern Saskatchewan and the Cypress Hills of southwestern SaskatchewanScoggan, H.J. 1957. Flora of Manitoba. Can. Dep. Northern Affairs and National Resources, Nat. Museum Can., Ottawa ON, Bull. 140. 619 p. and southeastern Alberta, northwestern Montana, south-central Montana, in the Black Hills on the Wyoming–South Dakota boundary, on the Manitoba–North Dakota boundary, and at Shushan, New York.Munns, E.N. 1938. The distribution of important forest trees of the United States. USDA, For. Serv., Washington DC, Misc. Publ. 287. 176 p.Fernald, M.L. 1950. Gray’s Manual of Botany, 8th ed. Amer. Book, New York NY. 1632 p.Cook, D.B.; Smith, R.H. 1959. A white spruce outlier at Shushan, New York. Ecology 40:333–337.

White spruce is the northernmost tree species in North America, reaching just north of 69°N latitude in the Mackenzie River delta. It grows between sea level and an elevation of . Its northern distribution roughly correlates to the location of the tree line, which includes an isothermic value of for mean temperature in July, as well as the position of the Arctic front; cumulative summer degree days, mean net radiation, and the amount of light intensities also figure. White spruce is generally found in regions where the growing season exceeds 60 days annually.

The southern edge of the zone in which white spruce forms 60% or more of the total stand corresponds more or less to the July isotherm of around the Great Lakes; in the Prairie Provinces its limit is north of this isotherm. During the summer solstice, day length values range from 17 hours at its southern limits to 24 hours above the Arctic Circle.

One of the hardiest conifers, white spruce in parts of its range withstands mean daily January temperature of and extreme minimum temperatures as low as ; minimum temperatures of are general throughout much of the range except the southernmost and southeasternmost parts.Fowells, H.A. 1965. ''Picea ''(spruces). p. 287–327'' in'' Silvics of Forest Trees of the United States. H.A. Fowells (Compiler), USDA, Forest Service, Washington DC, Agric. Handbook No. 271. By itself, or with black spruce and tamarack (''Larix laricina''), white spruce forms the northern boundary of tree-form growth.Sutton, R.F. 1969. Silvics of white spruce (''Picea glauca'' oenchVoss). Can. Dep. Fish. For., For. Branch, Ottawa ON, Publ. 1250. 57 p. (Cited in Coates et al. 1994). White spruce up to 15 m in height occur at 69°N on islands in the Mackenzie Delta near Inuvik in the Northwest Territories. Hustich (1966)Hustich, I. 1966. On the forest–tundra and the northern tree-lines. Annales Univ. Turku A.II, Vol. 36:7–47. depicted ''Picea'' spp. as forming the northernmost limit of tree growth in North America.

The arctic or northern timberline in North America forms a broad transition zone from Labrador to northern Alaska. In Labrador, white spruce is not abundant and constitutes less than 5% of the forest, with a range that coincides very closely with that of black spruce but extending slightly further north.Wilton, R.F. 1964. The forests of Labrador. Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1066. 72 p.

The range of white spruce extends westwards from Newfoundland and Labrador, and along the northern limit of trees to Hudson Bay, Northwest Territories, Yukon, and into northwestern Alaska. Across western Canada and Alaska, white spruce occurs further north than black spruce, and, while poplar (''Populus''), willow, and birch may occur along streams well into the tundra beyond the limits of spruce, the hardwoods are usually no more than scrub.Hustich, I. 1953. The boreal limits of conifers. Arctic 6:149–162. Spruce characteristically occurs in fingers of tree-form forest, extending far down the northern rivers and as scattered clumps of dwarfed “bush” spruce on intervening lands.Halliday, W.E.D.; Brown, A.W.A. 1943. The distribution of some important forest trees in Canada. Ecology 24:353–373. In Manitoba, Scoggan noted that the northernmost collection of white spruce was at latitude 59°48’N, but Bryson et al.Bryson, R.A.; Irving, W.H.; Larson, J.A. 1965. Radiocarbon and soil evidence of former forest in the southern Canadian tundra. Science 147(3653):46–48. found white spruce in the northern edge of continuous forest in central Canada at Ennadai Lake, about 60°45′ N, 101°’W, just north of the northwest corner of Manitoba. Bryson et al. noted that the forest retained “the same general characteristics as when it was first described Tyrell,_J.B._1897._Geol._Surv._Can.,_Ottawa_ON,_Ann._Rep._1896,_Vol._9._(Cited_by_Bryson_et_al._1965,_orig._not_seen).html" ;"title="y TyrrellTyrell, J.B. 1897. Geol. Surv. Can., Ottawa ON, Ann. Rep. 1896, Vol. 9. (Cited by Bryson et al. 1965, orig. not seen)">y TyrrellTyrell, J.B. 1897. Geol. Surv. Can., Ottawa ON, Ann. Rep. 1896, Vol. 9. (Cited by Bryson et al. 1965, orig. not seen)in 1896”. Collins and Sumner reported finding white spruce within 13 km of the Arctic coast in the Firth valley, Yukon, at about 69°30′ N, 139°30′ W, and Sargent noted that white spruce in Alaska “reached Behring Strait in 66°44′ N”.

Climate, especially temperature, is obviously a factor in determining distributions of northern flora. Halliday and Brown suggested that white spruce's northern limit corresponds “very closely” with the July mean monthly isotherm of 10 °C in Ungava, but that the northern limit west of Hudson Bay was south of that isotherm. Other climatic factors that have been suggested as affecting the northern limit of white spruce include: cumulative summer degree days, position of the Arctic front in July, mean net radiation especially during the growing season, and low light intensities. Topography, soil conditions, and glaciation may also be important in controlling northern limits of spruce.Drew, J.V.; Shanks, R.E. 1965. Landscape relationships of soils and vegetation in the forest–tundra ecotone, Upper Firth River Valley, Alaska–Canada. Ecol. Monogr. 35:285–306.

The southern limit of distribution of white spruce is more complex. From east of the main range of coastal mountains in British Columbia, the southern continuous limit of white spruce is the forest/prairie interface through Alberta, Saskatchewan, Manitoba, the northern parts of Minnesota and Wisconsin, central Michigan, northeastern New York, and Maine. Sargent and Harlow and Harrar also included Vermont and New Hampshire; and, while Dame and BrooksDame, L.L.; Brooks, H. 1901. Handbook of the Trees of New England. Ginn, Boston MA. 196 p. excluded New York and states further west, they included Massachusetts as far south as Amherst and Northampton, “probably the southern limit of the species” in that area. NisbetNisbet, J. 1905. The Forester. Blackwood and Sons, Edinburgh and London, U.K., Vol. 1. 506 p. gave the range of white spruce as extending to “Carolina”, but he did not recognize red spruce as a species and presumably included it with white spruce.

Towards the southern parts of its range, white spruce encounters increasingly effective ecological competition from hardwoods, some of which may reinforce their growth-rate or sprouting competitiveness with allelopathic depredation of coniferous regeneration.Tubbs, C.H. 1976. Effect of sugar maple root exudate on seedlings of northern conifer species. USDA, For. Serv., Res. Note NC-213. 2 p. Further southward extension of the distribution is inhibited by white spruce's cold requirement.

White spruce as an exotic species

As an exotic, white spruce is widespread but uncommon. It was introduced into EnglandHereman, S. 1868. Paxton’s Botanical Dictionary (Revised and corrected), Bradbury, Evans, London, U.K. 623 p. and parts of continental EuropeJackson, A.B. 1948. The Identification of Conifers. Arnold, London, U.K. 152 p. in or soon after the year 1700, into Denmark about 1790,Sabroe, A.S. 1954. Forestry in Denmark, 3rd ed. Danish Heath Soc., Copenhagen. 118 p. and into Tasmania and Ceylon shortly before 1932.Troup, H.S. 1932. Exotic Forest Trees in the British Empire. Clarendon Press, Oxford, U.K. 268 p.

Nisbet noted that firmly-rooted white spruce served very well to stabilize windswept edges of woods in Germany. In a narrow belt of mixed Norway and white spruces over an extremely exposed hilltop crest at high elevation in northern England, the Norway spruce were “completely dwarfed” whereas the white spruce had reached heights of between 3 and 4.3 m.Guillebaud, W.H.; Steven, H.M.; Marsden, R.E. 1920. Rate of growth of conifers in the British Isles. Forestry Commission, HMSO, London, U.K., Bull. 3. 84 p. The age of the belt was not recorded, but adjoining 66-year-old stands may have been of the same vintage.

White spruce has also been used as a minor plantation species in England and Scotland.Selby, P.J. 1842. A history of British forest-trees. Van Voorst, London. 540 p.Anon. (C.P.J.) 1879. Fir. pp. 222–225 ''in'' vol IX. Encyclopædia Britannica, 9th ed.United Kingdom Forestry Commission. 1920. Beaufort estate. p. 57–62 ''in'' Programme, British Empire For. Conf., London, U.K. In Scotland, at Corrour, Inverness-shire, Sir John Stirling Maxwell in 1907 began using white spruce in his pioneering plantations at high elevations on deep peat. However, plantations in Britain have generally been unsatisfactory,Edlin, H.L. 1962. A modern sylva or a discourse of forest trees. 3. The spruces. Quart J. For. 56:292–300. mainly because of damage by spring frosts after mild weather had induced flushing earlier in the season. However, the species is held in high regard in the Belgian peat region, where it grows better than do the other spruces.Fraser, G.K. 1933. Studies of certain Scottish Moorlands in relation to tree growth. For. Commission, HMSO, London, U.K. 112 p.

Ecology

White spruce is a climax canopy tree in the boreal forests of Canada and Alaska. It generally occurs on well-drained soils in alluvial and riparian zones, although it also occurs in soils of glacial and lacustrine origin. The understory is dominated by feather mosses (''Hylocomium splendens'', ''Pleurozium schreberi'', ''Ptilium crista-castrensis'') and fork mosses, and occasionally peat moss. In the far north, the total depth of the moss and underlying humus is normally between , although it tends to be shallower when hardwoods are present in the stand.

White spruce grows in soils with pH values of 4.7–7.0, although they have been found in soils as acidic as 4.0 in subalpine fir forests in the Northwest Territories. A presence of calcium in the soil is common to white spruce found in northern New York. White spruce most commonly grows in the soil orders of Alfisols and Inceptisols. Soil properties such as fertility, temperature, and structural stability are partial determinants of the ability of white spruce to grow in the extreme northern latitudes. In the northern limits of its range, white spruce is the climax species along with black spruce; birch and aspen are the early succession species.
Wildfires typically occur every 60 to 200 years, although they have been known to occur as infrequently as every 300 years.

White spruce will grow in USDA Growing Zones 3–7, but is not adapted to heat and humidity and will perform poorly in a hot climate. The tree attains its greatest longevity and growth potential in Zones 3–4.

Soils

White spruce occurs on a wide variety of soils, including soils of glacial, lacustrine, marine, and alluvial origins; overlying basic dolomites, limestones and acidic Precambrian and Devonian granites and gneisses; and Silurian sedimentary schists, shales, slates, and conglomerates.Halliday, W.E.D. (1937). "A forest classification for Canada." Can. Dep. Mines and Resources, Dominion For. Serv., Ottawa ON, Bull. 89. 50 p. The wide range of textures accommodated includes clays, even those that are massive when wet and columnar when dry, sand flats, and coarse soils.Wilde, S.A.; Wilson, F.G.; White, D.P. (1949). "Soils of Wisconsin in relation to silviculture." Wisconsin Conserv. Dep., Madison WI, Publ. 525–49. 171 p.Wilde, S.A.; Voigt, G.K.; Pierce, R.S. (1954). "The relationship of soils and forest growth in the Algoma district of Ontario, Canada." ''J. Soil Sci.'' 5:22–38.Nienstaedt, H. (1957). Silvical characteristics of white spruce (''Picea glauca''). USDA, For. Serv., Lake States For. Exp. Sta., St. Paul MN, Pap. 55. 24 p.Jameson, J.S. (1963). "Comparison of tree growth on two sites in the Riding Mountain Forest Experimental Area." Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1019. 36 p. Its occurrence on some organic soils is not characteristic, except perhaps on shallow mesic organic soils in Saskatchewan and in association with black spruce on organic soils in central Yukon.

Podzolized, brunisolic, luvisolic, gleysolic, and regosolic (immature) soils are typical of those supporting white spruce throughout the range of the species. Soils supporting white spruce are most commonly Alfisols or Inceptisols. In the podzol region of Wisconsin, white spruce occurs on loam podzols, podzolized gley loams, strongly podzolized clays, gley-podzol clays, stream-bottom soils, and wood peat. Moist sandy loams also support good growth. On sandy podzols, it is usually a minor species. Good development occurs on moist alluvium on the banks of streams and borders of swamps.Jeffrey, W.W. (1961). "Origin and structure of some white spruce stands on the lower Peace River." Can. Dep. For., For. Res. Branch, Ottawa ON, Tech. Note 103. 20 p.Jeffrey, W.W. (1964). "Forest types along lower Liard River, Northwest Territories." Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1035. 103 p.Lacate, D.S.; Horton, K.W.; Blyth, A.W. (1965). "Forest conditions on the Lower Peace River." Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1094. 53 p.Viereck, L.A. (1973). "Wildfire in the taiga of Alaska." ''Quaternary Res.'' 3:465–495.Sargent, C.S. 1898. The Silva of North America. A description of the trees which grow naturally in North America exclusive of Mexico. Vol. XII. Coniferae. Houghton Mifflin, Riverside Press, Cambridge, Boston MA. 144 p.Kenety, W.H. (1917). "Preliminary study of white spruce in Minnesota." ''Univ. Minnesota, Cloquet Exp. Sta. MN, Bull.'' 168. 30 p. White spruce makes good growth on well-drained lacustrine soils in Alberta Mixedwoods,Heger, L. (1971). "Site-index/soil relationships for white spruce in Alberta mixedwoods." Can. Dep. Environ., Can. For. Serv., For. Manage. Instit., Ottawa ON, Inf. Rep. FMR-X-32. 15 p. on moderately-well-drained clay loams in Saskatchewan,,Kabzems, A. (1971). "Growth and yield of well stocked white spruce in the mixedwood section , Saskatchewan. Saskatchewan." Dep. Nat. Resour., For. Branch, Prince Albert SK, Tech. Bull. 5. 75 p. (Cited in Coates et al. 1994). and on melanized loams and clays (with sparse litter and a dark-coloured organically-enriched mineral horizon) in the Algoma district of Ontario.

White spruce becomes less accommodating of soil with increasing severity of climate. The distribution of white spruce in Labrador seems to depend almost entirely on the character of the soil, and between the southwestern shores of Hudson Bay and the northeastern regions of Saskatchewan, white spruce is confined to very local physiographic features, characterized by well-drained or fertile soils.Ritchie, J.C. 1956. The vegetation of northern Manitoba. I. Studies in the southern spruce forest zone. Can. J. Bot. 34(4):523–561.

On dry, deep, outwash deposits in northern Ontario, both white spruce and aspen grow slowly.MacLean, D.W. (1960). "Some aspects of the aspen–birch–spruce–fir type in Ontario." Can. Dep. Northern Affairs National Resources, For. Branch, For. Res. Div., Ottawa ON, Tech. Note 94. 24 p. But, broadly, white spruce is able to tolerate considerable droughtiness of sites that are fertile, and no fertile site is too moist unless soil moisture is stagnant.Sutton, R.F. (1968). Ecology of young white spruce (''Picea glauca'' oenchVoss). Ph.D. thesis, Cornell Univ., Ithaca NY, Univ. Microfilms, Ann Arbor, Michigan MI, 68–11645. 500 p. Soil fertility holds the key not just to white spruce growth but to the distribution of the species. At least moderate fertility is needed for good growth, but white spruce occurs on many sites where nutrient deficiencies depress its growth more than that of black spruce, red spruce, Norway spruce, and the pines generally. Minimum soil-fertility standards recommended for white spruce sufficient to produce 126 to 157 m³/ha of wood at 40 years are much higher than for pine species commonly planted in the Lake States (Wilde 1966):Wilde, S.A. (1966). "Soil standards for planting Wisconsin conifers." ''J. For.'' 64(6):389–391. 3.5% organic matter, 12.0 meq/100 g exchange capacity, 0.12% total N, 44.8 kg/ha available P, 145.7 kg/ha available K, 3.00 meq/100 g exchangeable Ca, and 0.70 meq/100 g exchangeable Mg.

Forest floors under stands dominated by white spruce respond in ways that vary with site conditions, including the disturbance history of the site. Composition, biomass, and mineral soil physical and chemical properties are affected. In Alaska, the accumulation of organic layers (to greater thicknesses in mature stands of spruce than those in hardwood stands on similar sites) leads to decreased soil temperatures, in some cases leading to the development of permafrost.Viereck, L.A. (1970a). "Forest succession and soil development adjacent to the Chena River in interior Alaska." ''Arctic Alp. Res.'' 2(1):1–26. S. BA51:76183/ref>Viereck, L.A. (1970b). Soil temperatures in river bottom stands in interior Alaska. p. 223–233 ''in'' Proc. Ecology of the Subarctic Regions, July–Aug. 1966, Helsinki, Finland, UNESCO. ienstaedt and Zasada 1990/ref>Viereck, L.A.; Dyrness, C.T.; Van Cleve, K.; Foote, M.J. (1983). "Vegetation, soils, and forest productivity in selected forest types in interior Alaska." ''Can. J. For. Res.'' 13(5):703–720. Acidity of the mineral soil sampled at an average depth of 17 cm in 13 white spruce stands on abandoned farmland in Ontario increased by 1.2 pH units over a period of 46 years.Brand, D.G.; Kehoe, P.; Connors, M. (1986). " Coniferous afforestation leads to soil acidification in central Ontario." ''Can. J. For. Res.'' 16(6):1389–1391.

A considerable range of soil pH is tolerated by white spruce. Thrifty stands of white spruce in Manitoba have developed on soils of pH 7.6 at only 10 cm below the surface, and pH 8.4 at 43 cm below the surface;Stoeckeler, J.H. (1938). "Soil adaptability of white spruce." ''J. For.'' 36:1145–1147. rooting depth in those soils was at least 81 cm. An abundant calcium supply is common to most white spruce locations in New York state. Chlorosis was observed in young white spruce in heavily limed nursery soils at about pH 8.3. Wilde gave 4.7 to 6.5 as the approximate optimum range of pH for white spruce in Wisconsin, but optimum growth seems possible at pH levels up to 7.0 and perhaps higher. Alluvium on the floodplains of northern rivers shows pH levels from 5.0 to 8.2.Zasada, J.C.; Van Cleve, K.; Werner, R.A.; McQueen, J.A.; Nyland, E. (1977). "Forest biology and management in high-latitude North American forests." p. 137–195'' in'' Proc. North American Forest Lands at Latitudes North of 60 degrees. Sympos., Univ. Alaska, Fairbanks AK, Sept. 19–22, 1977. High-lime ecotypes may exist,Pelletier, J.R. (1966). "Tree breeding in Canada." ''Commonw. For. Rev.'' 45(1):9–10. and in Canada Forest Section B8 the presence of balsam poplar and white spruce on some of the moulded moraines and clays seems to be correlated with the considerable lime content of these materials,Stiell, W.M. (1976). "White spruce: artificial regeneration in Canada." Dep. Environ., Can. For. Serv., Ottawa ON, Inf. Rep. FMR-X-85. 275 p. while calcareous soils are favourable sites for northern outliers of white spruce.

Mature stands of white spruce in boreal regions often have well-developed moss layers dominated by feather mosses, e.g., ''Hylocomium splendens'', ''Pleurozium schreberi'', '' Ptlium crista-castrensis'', and '' Dicranum'', rather than ''Sphagnum''.La Roi, G.H.; Stringer, M.H. (1976). Ecological studies in the boreal spruce–fir forests of the North American taiga. II. Analysis of the bryophyte flora. Can. J. Bot. 54:619–643. ienstaedt and Zasada 1990/ref>Viereck, E.G. (1987). Alaska’s wilderness medicines – healthful plants of the North. Alaska Publishing, Edmonds, Washington WA. 107 p. ienstaedt and Zasada 1990/ref> The thickness of the moss–organic layer commonly exceeds 25 cm in the far north and may approach twice that figure. The mosses compete for nutrients and have a major influence on soil temperatures in the rooting zone. Permafrost development in parts of Alaska, Yukon, and the Northwest Territories is facilitated by the insulative organic layer (Viereck 1970a, b, Gill 1975, Van Cleve and Yarie 1986).Gill, D. (1975). "Influence of white spruce trees on permafrost-table microtopography, Mackenzie River Delta." ''Can. J. Earth Sci.'' 12(2):263–272.Van Cleve, K.; Yarie, J. (1986). "Interaction of temperature, moisture, and soil chemistry in controlling nutrient cycling and ecosystem development in the taiga of Alaska." p. 160–189 ''in'' Van Cleve, K.; Chapin, F.S.; Flanagan, P.W.; Viereck, L.A.; Dyrness, C.T. (Eds.). (1986). ''Forest Ecosystems in the Alaskan Taiga.'' Springer-Verlag, New York NY.

Cold hardiness

White spruce is extremely hardy to low temperatures, provided the plant is in a state of winter dormancy. Throughout the greater part of its range, white spruce routinely survives and is undamaged by winter temperatures of , and even lower temperatures occur in parts of the range. Boreal ''Picea'' are among the few extremely hardy conifers in which the bud primordia are able to survive temperatures down to .Sakai, A.; Larcher, W. (Eds.) (1987). ''Frost Survival of Plants.'' Springer-Verlag, New York NY. 321 p.

Especially important in determining the response of white spruce to low temperatures is the physiological state of the various tissues, notably the degree of "hardening" or dormancy. A natural progression of hardening and dehardening occurs in concert with the seasons.Glerum, C. (1985). "Frost hardiness of coniferous seedlings: principles and applications." p. 107–123 ''in ''Duryea, M.L. (Ed.). Proceedings: Evaluating seedling quality: principles, procedures, and predictive abilities of major tests. Workshop, October 1984, Oregon State Univ., For. Res. Lab., Corvallis OR. While different tissues vary in ability to tolerate exposure to stressful temperatures, white spruce, as with woody plants in general, has necessarily developed sufficient winter hardiness in its various tissues to enable them to survive the minimum temperatures experienced in the distribution range.

White spruce is subject to severe damage from spring frosts. Newly flushed shoots of white spruce are very sensitive to spring frost.Smith, B.J. (1949). "Silvicultural work at the Sault Ste. Marie Division f Abitibi Power and Paper Co. Ltd." Can. Pulp Paper Assoc., Woodlands Section, Woodlands Section Index No. 1050 (F-2). 4 p. This sensitivity is a major constraint affecting young trees planted without overstorey nurses in boreal climates.Sutton, R.F. (1992). "White spruce (''Picea glauca'' oenchVoss): stagnating boreal old-field plantations unresponsive to fertilization and weed control." ''For. Chron.'' 68:249–258.

Forest succession

Forest succession in its traditional sense implies two important features that resist direct examination.Solomon, A.M.; West, D.C., and Solomon, J.A. 1981. Simulating the role of climate change and species imiigration in forest succession. p. 154–178 ''in'' West, D.C.; Shugart, H.H.; Botkin, D.B. (Eds.). Forest Succession: Concepts and Application. Springer-Verlag, New York NY. First, classical definitions generally connote directional changes in species composition and community structure through time, yet the time frame needed for documentation of change far exceeds an average lifespan. The second feature that defies quantitative description is the end point or climax.

Floodplain deposits in the Northwest Territory, Canada, are important in relation to the development of productive forest types with a component of white spruce. The most recently exposed surfaces are occupied by sandbar vegetation or riparian shrub willows and ''Alnus incana''. With increasing elevation, the shrubs give way successively to balsam poplar and white spruce forest. In contrast, older floodplains, with predominantly brown wooded soils, typically carry white spruce– trembling aspen mixedwood forest.

Interrelationships among nutrient cycling, regeneration, and subsequent forest development on floodplains in interior Alaska were addressed by Van Cleve et al.,Van Cleve, K.; Dyrness, R.; Viereck, L. 1980. Nutrient cycling in interior Alaska flood plains. p. 11–18 ''in'' Murray, M.; Van Veldhuizen, R.M. (Eds.). Proc. Workshop, Fairbanks, Alaska, Nov. 1979. USDA, For. Serv., Pacific Northwest For. Exp. Sta., Portland OR, Gen. Tech. Rep., PNW-107. 52 p. who pointed out that the various stages in primary succession reflect physical, chemical, and biological controls of ecosystem structure and function. Thus, each successional stage has a species combination in harmony with site quality. Short-circuiting succession by planting a late successional species such as white spruce on an early successional surface may result in markedly reduced growth rates because of nitrogen insufficiency. Without application of substantial amounts of fertilizer, use would have to be made of early successional alder and its site-ameliorating additions of nitrogen.

Neiland and Viereck noted that “the slow establishment and growth of spruce under birch stands n Alaskamay be partially due to effects of shading and general competition for water and nutrients, but may also be more directly related to the birch itself. HeikinheimoHeikinheimo, O. 1915. Der einfluss der brandwirtschaft auf die Wälder Finnlands. Kaskiviljelyksen Vaikutus Suomen Metsin. Acta Forest. Fenn. 4:1–264, 1–149, 1–59 erman summary p 1–59/ref>Lutz, H.J. 1956. Ecological effects of forest fires in the interior of Alaska. USDA, For. Serv., Washington DC, Tech. Bull. 1133. 121 p. found that birch ash inhibited white spruce seedlings, and GregoryGregory, R.A. 1966. The effect of leaf litter upon establishment of white spruce beneath paper birch. For. Chron. 42:251–255. found that birch litter has a smothering effect on spruce seedlings.".Neiland, B.J.; Viereck, L.A. 1977. Forest types and ecosystems. p. 109–136 ''in'' North American Forest Lands at Latitudes North of 60 Degrees, Proc. sympos., Univ. Alaska, Fairbanks AK, Sept. 1977.

On dry upland sites, especially south-facing slopes, the mature vegetation is white spruce, white birch, trembling aspen, or a combination of these species. Succession follows in one of two general patterns. In most cases, aspen and birch develop as a successional stage after fire before reaching the spruce stage. But, occasionally, with optimal site conditions and a source of seed, white spruce will invade with the hardwoods or within a few years thereafter, thereby producing even-aged white spruce stands without an intervening hardwood stage.

Associated forest cover

The White Spruce Cover Type may include other species in small numbers. In Alaska, associates include paper birch, trembling aspen, balsam poplar, and black spruce; in western Canada, additional associates are subalpine fir, balsam fir, Douglas-fir, jack pine, and lodgepole pine.Dyrness, C.T. 1980. Western forest cover types, Northern Interior (Boreal): White spruce. p.81; White spruce–Aspen. p.82; Black spruce–White spruce. p.84; and Black spruce–Paper birch. p.85. ''in'' Eyre, F.H. (Ed.). Forest Cover Types of the United States and Canada. Soc. Amer. Foresters, Washington DC. Seral species giving way to white spruce include paper birch, aspen, balsam poplar, jack pine, and lodgepole pine. On certain river bottom sites, however, black spruce may replace white spruce. Earlier successional stages leading to the white spruce climax are the white spruce–paper birch, white spruce–aspen, balsam poplar, jack pine, and lodgepole pine types. The type shows little variation. The forest is generally closed and the trees well formed, other than those close to the timberline. Lesser vegetation in mature stands is dominated by mosses. Vascular plants are typically few, but shrubs and herbs that occur “with a degree of regularity” include: alder, willows, mountain cranberry, red-fruit bearberry, black crowberry, prickly rose, currant, buffaloberry, blueberry species, bunchberry, twinflower, tall lungwort, northern comandra, horsetail, bluejoint grass, sedge species, as well as ground-dwelling mosses and lichen

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