Picea glauca
Template:Short description Template:Speciesbox Template:Infobox genome
Picea glauca, the white spruce,<ref>Template:PLANTS</ref> is a species of spruce native to the northern temperate and boreal forests in Canada and United States, North America.
Picea glauca is native from central Alaska all through the east, across western and southern/central Canada to the Avalon Peninsula in Newfoundland, Quebec, Ontario and south to Montana, North Dakota, 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.<ref name=farjonrushforthc>Template:Cite book</ref><ref>Template:Cite book</ref><ref name="iucn status 12 November 2021" /><ref>Template:Gymnosperm Database</ref> It is also known as Canadian spruce, skunk spruce, cat spruce, Black Hills spruce, western white spruce, Alberta white spruce, and Porsild spruce.<ref name="SilvicsNA">Template:Silvics</ref>
DescriptionEdit
The white spruce is a large evergreen conifer which normally grows to Template:Convert tall, but can grow up to Template:Convert tall<ref name="tktimb">Template:Cite book</ref> with a trunk diameter of up to Template:Convert. The bark is thin and scaly, flaking off in small circular plates Template:Convert across. The crown is narrowTemplate:Sndconical 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, Template:Convert 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.<ref name=farjonrushforthc/><ref name="tktimb" />
The cones are pendulous, slender, cylindrical, Template:Convert long<ref name="tktimb" /> 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, tan wing 5 to 8 mm long.<ref name=farjonrushforthc/>
- Picea glauca sapling Kluane NP.jpg
Young tree
- 2009-05-13 EPB mature (02) DDumais.jpg
Mature tree
- P1260709 DDumais.jpg
Mature tree sans lower branches
- Picea glauca-bark.jpg
The bark is thin and scaly, flaking off in small roundish plates.
- Picea glauca twig Denali NP AK.jpg
Twig with needles
- Picea glauca Świerk biały 2011-09-11 03.jpg
Mature female cone
- Picea glauca Brno3.JPG
Female cone
- Picea glauca young female cone - Keila.jpg
Young female cone
- Picea glauca 2.jpg
Male cone and pollen
SeedsEdit
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.<ref name="waldron2">Template:Cite journal</ref><ref name="zas1">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. [Coates 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.<ref>Hellum, A.K. 1976. Grading seed by weight in white spruce. USDA, For. Serv., Tree Plant. Notes 27(1):16–17, 23–24. (Cited in Coates et al. 1994).
- Zasada, J.C.; Foote, M.J.; Deneke, F.J.; Parkerson, R.H. 1978. Case history of an excellent white spruce cone and seed crop in interior Alaska: cone and seed production, germination and seedling survival. USDA, For. Serv., Pacific NW For. Range Exp. Sta., Portland OR, Gen. Tech. Rep. PNW-65. 53 p.</ref>
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.<ref name="cross2">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.</ref> Mature seeds "snaps in two" when cut by a sharp knife on a firm surface.<ref name="cross2" />
White spruce cones reach their maximum size after 800 GDD. Cone moisture content decreases gradually after about 1000 GDD.<ref name="cram2">Cram, W.H.; Worden, H.A. 1957. Maturity of white spruce cones and seed. For. Sci. 3:263–269.</ref>
Cone colour also can be used to help determine the degree of maturation, but cones may be red, pink or green.<ref name="teich">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.</ref> Collection and storage dates and conditions influence germination requirements and early seedling growth.<ref name="zas2">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. [Coates et al. 1994]</ref><ref name="edwards2">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.</ref><ref name="wins">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.</ref>
A bushel (35 L) of cones, which may contain 6,500 to 8,000 cones, yields Template:Convert of clean seed.<ref name="usda">USDA Forest Service. 1948. Woody-plant Seed Manual. USDA, For. Serv., Washington DC, Misc. Publ. 654. 416 p.</ref>
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.<ref name="cram2" /><ref name="zas2" /><ref name="wins" /> 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.<ref name="SilvicsNA" /> 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.<ref name="zas5">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.</ref><ref name="rowea">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.</ref> Seed dispersal occurs mainly in late summer or early fall.<ref name="waldron2" />
White spruce seed is initially dispersed through the air by wind. Both the initiation and pattern of seed dispersal depend on the weather,<ref name="SilvicsNA" /> but these can vary among trees in the same stand.<ref name="zas5" /> 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.<ref name="zas5" />
Root systemEdit
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.<ref name="wagg1">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.</ref><ref name="wagg2">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.</ref> 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.<ref name="sutton3">Sutton, R.F. 1969. Form and development of conifer root systems. Commonw. For. Bureau, Oxford, U.K., Tech. Communication No. 7. 131 p.</ref> In the nursery, or naturally in the forest, white spruce usually develops several long 'running' roots just below the ground surface.<ref name="mullin1">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.</ref>
The structure of the tracheids in the long lateral roots of white spruce varies with soil nitrogen availability.<ref name="kraso">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.</ref>
StemEdit
White spruce can live for several hundred years, with an estimated average lifespan of 250 to 300 years.<ref name="dall">Dallimore, W.; Jackson, A.B. 1961. A Handbook of Coniferae including Ginkgoaceae, 3rd (1948) ed. reprinted with corrections. Arnold, London, U.K. 686 p.</ref>
Slow-growing trees in rigorous climates are also capable of great longevity. White spruce Template:Convert high on the shore of Urquhart Lake, Northwest Territories, were found to be more than 300 years old.<ref name="hare">Hare, F.K.; Ritchie, J. 1972. The boreal bioclimates. Geogr. Rev. 62:333–365.</ref>
BarkEdit
The bark of mature white spruce is scaly or flaky, grey-brown or ash-brown, but silvery when freshly exposed.<ref name="bray">Brayshaw, T.C. 1960. Key to the native trees of Canada. Canada Dep. For., Bull. 125. 43 p.</ref><ref name="harlow">Harlow, W.M.; Harrar, E.S. 1950. Textbook of Dendrology, 3rd ed. McGraw-Hill, New York NY. 555 p.</ref> Resin blisters are normally lacking, but the Porsild spruce Picea glauca var. porsildii Raup has been credited with having smooth resin-blistered bark.<ref name="hosie">Hosie, R.C. 1969. Native Trees of Canada, 7th ed. Can. Dep. Fish. For., Can. For. Serv., Ottawa ON. 380 p.</ref>
White spruce bark is mostly less than 8 mm and not more than 9.5 mm thick.<ref name="hale3">Hale, J.D. 1955. Thickness and density of bark. Pulp and Paper Mag. Canada, Dec.:3–7.</ref><ref name="chang2">Chang, Y.P. 1954. Bark structure of North American conifers. USDA, For. Serv., Tech. Bull. 1095. 86 p.</ref>
ChemistryEdit
Isorhapontin can be found in spruce species such as the white spruce.<ref>Template:Cite journal</ref>
P. glauca has three different genomes; a nuclear genome,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> a mitochondrial genome,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and a plastid (i.e. chloroplast) genome.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The large (20 Gbp) nuclear genome of P. glauca (genotype WS77111) was published in 2015,<ref>Template:Cite journal</ref> and the organellar (plastid and mitochondrial) genomes (genotype PG29) were published in SD Jackman et al. 2015.<ref>Template:Cite journal</ref> The plastid genome of P. glauca (genotype WS77111) has also been published.<ref>Template:Cite journal</ref>
VarietiesEdit
Several geographical varieties have been described, but are not accepted as distinct by all authors. These comprise, from east to west:<ref name="farjonrushforthc" />
- Picea glauca var. glauca (typical or eastern white spruce): from Newfoundland west to eastern Alberta, on lowland plains.
- Picea glauca var. densata (Black Hills white spruce): The Black Hills in South Dakota.
- Picea glauca var. albertiana (Alberta white spruce): The Rocky Mountains in Alberta, British Columbia and northwest Montana.
- Picea glauca var. porsildii (Alaska white spruce): Alaska and Yukon.
The two western varieties are distinguished by pubescent shoots. It may be related to extensive hybridisation and intergradation with the closely related Engelmann spruce found further south in the Rocky Mountains, which forms the nothospecies Picea × albertiana. White spruce also hybridises readily with the closely related Sitka spruce where they meet in southern Alaska and northwestern British Columbia; this hybrid is known as Picea × lutzii.<ref name="farjonrushforthc" />
Distribution and habitatEdit
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.<ref name="rowe">Rowe, J.S 1972. Forest regions of Canada. Can. Dep. Environ., Can. For. Serv., Ottawa ON, Publ. 1300. 172 p.</ref><ref name="forest">Forestry Branch. 1961. Native Trees of Canada, 6th ed. Canada Dep. Northern Affairs and National Resour., For. Branch, Ottawa ON, Bull. 61. 291 p.</ref> 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°".<ref name="bell">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.</ref> Collins and Sumner<ref name="collins">Collins, G.L.; Sumner, L. 1953. Northeast Arctic: the last great wilderness. Sierra Club Bull. 38:13–26.</ref> 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The wide variety of ecological conditions in which 4 Quebec conifers, including white spruce, are able to establish themselves, was noted by Lafond,<ref name="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.</ref> 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,<ref name="harlow"/><ref name="sargent2">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. [E3999 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.<ref name="SilvicsNA" />
Southern outliers have been reported in southern Saskatchewan and the Cypress Hills of southwestern Saskatchewan<ref name="SilvicsNA" /><ref name="scoggan">Scoggan, H.J. 1957. Flora of Manitoba. Can. Dep. Northern Affairs and National Resources, Nat. Museum Can., Ottawa ON, Bull. 140. 619 p.</ref> and southeastern Alberta,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> northwestern Montana,<ref name="harlow" /> south-central Montana, in the Black Hills on the Wyoming–South Dakota boundary, on the Manitoba–North Dakota boundary, and at Shushan, New York.<ref name="munns">Munns, E.N. 1938. The distribution of important forest trees of the United States. USDA, For. Serv., Washington DC, Misc. Publ. 287. 176 p.</ref><ref name="fernald">Fernald, M.L. 1950. Gray’s Manual of Botany, 8th ed. Amer. Book, New York NY. 1632 p.</ref><ref name="cook2">Cook, D.B.; Smith, R.H. 1959. A white spruce outlier at Shushan, New York. Ecology 40:333–337.</ref>
White spruce is the northernmost tree species in North America, reaching just north of 69°N latitude in the Mackenzie River delta.<ref>Arno, S. F. & Hammerly, R. P. (1984). Timberline. Mountain and Arctic Forest Frontiers. The Mountaineers, Seattle. Template:ISBN.</ref> It grows between sea level and an elevation of Template:Convert. Its northern distribution roughly correlates to the location of the tree line, which includes an isothermic value of Template:Convert 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.<ref name="SilvicsNA" />
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 Template:Convert 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.<ref name="SilvicsNA" />
One of the hardiest conifers, white spruce in parts of its range withstands mean daily January temperature of Template:Convert and extreme minimum temperatures as low as Template:Convert; minimum temperatures of Template:Convert are general throughout much of the range except the southernmost and southeasternmost parts.<ref name="fowells">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.</ref> By itself, or with black spruce and tamarack (Larix laricina), white spruce forms the northern boundary of tree-form growth.<ref name="sutton2">Sutton, R.F. 1969. Silvics of white spruce (Picea glauca [Moench] Voss). Can. Dep. Fish. For., For. Branch, Ottawa ON, Publ. 1250. 57 p. (Cited in Coates et al. 1994).</ref> 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)<ref name="hust2">Hustich, I. 1966. On the forest–tundra and the northern tree-lines. Annales Univ. Turku A.II, Vol. 36:7–47.</ref> 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.<ref name="wilton">Wilton, R.F. 1964. The forests of Labrador. Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1066. 72 p.</ref>
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.<ref name="fowells" /> 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.<ref name="hust1">Hustich, I. 1953. The boreal limits of conifers. Arctic 6:149–162.</ref> 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.<ref name="munns" /><ref name="hall2">Halliday, W.E.D.; Brown, A.W.A. 1943. The distribution of some important forest trees in Canada. Ecology 24:353–373.</ref> In Manitoba, Scoggan<ref name="scoggan" /> noted that the northernmost collection of white spruce was at latitude 59°48’N, but Bryson et al.<ref name="bryson">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.</ref> 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.<ref name="bryson" /> noted that the forest retained "the same general characteristics as when it was first described [by Tyrrell<ref name="tyrell">Tyrell, J.B. 1897. Geol. Surv. Can., Ottawa ON, Ann. Rep. 1896, Vol. 9. (Cited by Bryson et al. 1965, orig. not seen)</ref>] in 1896". Collins and Sumner<ref name="collins" /> 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<ref name="sargent2" /> noted that white spruce in Alaska "reached Behring Strait in 66°44′ N".
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Climate, especially temperature, is obviously a factor in determining distributions of northern flora. Halliday and Brown<ref name="hall2" /> 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.<ref name="SilvicsNA" /> Topography, soil conditions, and glaciation may also be important in controlling northern limits of spruce.<ref name="drew">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.</ref>
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.<ref name="fowells" /> Sargent<ref name="sargent2" /> and Harlow and Harrar<ref name="harlow" /> also included Vermont and New Hampshire; and, while Dame and Brooks<ref name="dame">Dame, L.L.; Brooks, H. 1901. Handbook of the Trees of New England. Ginn, Boston MA. 196 p.</ref> 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. Nisbet<ref name="nisbet">Nisbet, J. 1905. The Forester. Blackwood and Sons, Edinburgh and London, U.K., Vol. 1. 506 p.</ref> 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.<ref name="tubbs">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.</ref> Further southward extension of the distribution is inhibited by white spruce's cold requirement.
As an exotic speciesEdit
As an exotic, white spruce is widespread but uncommon. It was introduced into England<ref name="hereman">Hereman, S. 1868. Paxton's Botanical Dictionary (Revised and corrected), Bradbury, Evans, London, U.K. 623 p.</ref> and parts of continental Europe<ref name="nisbet" /><ref name="jackson">Jackson, A.B. 1948. The Identification of Conifers. Arnold, London, U.K. 152 p.</ref> in or soon after the year 1700, into Denmark about 1790,<ref name="sabroe">Sabroe, A.S. 1954. Forestry in Denmark, 3rd ed. Danish Heath Soc., Copenhagen. 118 p.</ref> and into Tasmania and Ceylon shortly before 1932.<ref name="troup">Troup, H.S. 1932. Exotic Forest Trees in the British Empire. Clarendon Press, Oxford, U.K. 268 p.</ref>
Nisbet<ref name="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.<ref name="guill">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.</ref> 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.<ref name="selby">Selby, P.J. 1842. A history of British forest-trees. Van Voorst, London. 540 p.</ref><ref name="anon">Anon. (C.P.J.) 1879. Fir. pp. 222–225 in vol IX. Encyclopædia Britannica, 9th ed.</ref><ref name="united">United Kingdom Forestry Commission. 1920. Beaufort estate. p. 57–62 in Programme, British Empire For. Conf., London, U.K.</ref> 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,<ref name="edlin">Edlin, H.L. 1962. A modern sylva or a discourse of forest trees. 3. The spruces. Quart J. For. 56:292–300.</ref> 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 other spruces.<ref name="fraser">Fraser, G.K. 1933. Studies of certain Scottish Moorlands in relation to tree growth. For. Commission, HMSO, London, U.K. 112 p.</ref>
EcologyEdit
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.<ref name="SilvicsNA" /> The understory is dominated by feather mosses (Hylocomium splendens, Pleurozium schreberi, Ptilium crista-castrensis) and fork mosses, and occasionally peat moss.<ref name="Trainor">Template:Cite journal</ref> In the far north, the total depth of the moss and underlying humus is normally between Template:Convert, although it tends to be shallower when hardwoods are present in the stand.<ref name="SilvicsNA" />
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.<ref name="SilvicsNA" /> 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.<ref name="Trainor" /> Wildfires typically occur every 60 to 200 years, although they have been known to occur as infrequently as every 300 years.<ref name="Trainor" />
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.Template:Citation needed The tree attains its greatest longevity and growth potential in Zones 3–4.
Wildlife such as deer, rabbits, and grouse browse the foliage during the winter.<ref>Template:Cite book</ref> The seeds are eaten by small mammals like the red squirrel and birds such as chickadee, nuthatch, and pine siskin.<ref name="tktimb" />
SoilsEdit
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.<ref name="hall">Halliday, W.E.D. (1937). "A forest classification for Canada." Can. Dep. Mines and Resources, Dominion For. Serv., Ottawa ON, Bull. 89. 50 p.</ref> The wide range of textures accommodated includes clays, even those that are massive when wet and columnar when dry, sand flats, and coarse soils.<ref name="rowe"/><ref name="wilde1">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.</ref><ref name="wilde2">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.</ref><ref name="nien1">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.</ref><ref name="jame2">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.</ref> 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.<ref name="SilvicsNA" />
Podzolized, brunisolic, luvisolic, gleysolic, and regosolic (immature) soils are typical of those supporting white spruce throughout the range of the species.<ref name="nien1" /> Soils supporting white spruce are most commonly Alfisols or Inceptisols.<ref name="SilvicsNA" /> 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.<ref name="wilde1" /> Moist sandy loams also support good growth.<ref name="harlow"/> On sandy podzols,<ref name="wilde1" /> it is usually a minor species.<ref name="SilvicsNA" /> Good development occurs on moist alluvium on the banks of streams and borders of swamps.<ref name="nien1" /><ref name="jeff1">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.</ref><ref name="jeff2">Jeffrey, W.W. (1964). "Forest types along lower Liard River, Northwest Territories." Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1035. 103 p.</ref><ref name="lacate">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.</ref><ref name="vier3">Viereck, L.A. (1973). "Wildfire in the taiga of Alaska." Quaternary Res. 3:465–495.</ref><ref name="rowe" /><ref name="sargent">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.</ref><ref name="ken">Kenety, W.H. (1917). "Preliminary study of white spruce in Minnesota." Univ. Minnesota, Cloquet Exp. Sta. MN, Bull. 168. 30 p.</ref> White spruce makes good growth on well-drained lacustrine soils in Alberta Mixedwoods,<ref name="heger">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.</ref> on moderately-well-drained clay loams in Saskatchewan,,<ref name="kabzems">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).</ref> and on melanized loams and clays (with sparse litter and a dark-coloured organically-enriched mineral horizon) in the Algoma district of Ontario.<ref name="wilde2" />
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,<ref name="sargent" /> 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.<ref name="ritch">Ritchie, J.C. 1956. The vegetation of northern Manitoba. I. Studies in the southern spruce forest zone. Can. J. Bot. 34(4):523–561.</ref>
On dry, deep, outwash deposits in northern Ontario, both white spruce and aspen grow slowly.<ref name="macl">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.</ref> 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.<ref name="sutton">Sutton, R.F. (1968). Ecology of young white spruce (Picea glauca [Moench] Voss). Ph.D. thesis, Cornell Univ., Ithaca NY, Univ. Microfilms, Ann Arbor, Michigan MI, 68–11645. 500 p.</ref> 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.<ref>Heiberg, S.O.; White, D.P. (1951). "Potassium deficiency of reforested pine and spruce stands in northern New York." Soil Sci. Soc. Amer. Proc. 15:369–376.
-Lafond, A. (1954). Les déficiences en potassium et magnésium des plantations de Pinus strobus, Pinus resinosa et Picea glauca de la province de Québec. Assoc. Ing. For. Prov. Québec, Texte des Conf. 34 Assemb. Ann.:65–82.
- McLeod, J.W. 1956. Plantations of the Acadia Forest Experiment Station. Can. Dep. Northern Affairs National Resour., For. Branch, For. Res. Div., Ottawa ON, Tech. Note 31. 25 p.
- MacArthur, J.D. 1957. The effects of manure on a white and Norway spruce plantation at Grand’Mère, Quebec. Can. Dep. Northern Affairs National Resour., For. Branch, For. Res. Div., Ottawa ON, Tech. Note 64. 15 p.< br>- Paine, L.A. 1960. Studies in forest pathology. XXII. Nutrient deficiencies and climatic factors causing low volume production and active deterioration in white spruce. Can. Dep. Agric., For. Biol. Div., Ottawa ON, Publ. 1067. 29 p.
- Swan, H.S.D. 1960. The mineral nutrition of Canadian pulpwood species. 1. The influence of nitrogen, phosphorus, potassium and magnesium deficiencies on the growth and development of white spruce, black spruce, jack pine and western hemlock seedlings grown in a controlled environment. Pulp Paper Res. Instit. Can., Montreal QC, Woodlands Res. Index No. 116, Tech. Rep. 168. 66 p.</ref> 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):<ref name="wilde3">Wilde, S.A. (1966). "Soil standards for planting Wisconsin conifers." J. For. 64(6):389–391.</ref> 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.<ref name="SilvicsNA" /> 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.<ref name="viera">Viereck, L.A. (1970a). "Forest succession and soil development adjacent to the Chena River in interior Alaska." Arctic Alp. Res. 2(1):1–26. [wS. BA51:76183]</ref><ref name="vierb">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. [Nienstaedt and Zasada 1990]</ref><ref name="vier4">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.</ref> 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.<ref name="brand">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.</ref>
A considerable range of soil pH is tolerated by white spruce.<ref name="nien1" /> 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;<ref name="stoe">Stoeckeler, J.H. (1938). "Soil adaptability of white spruce." J. For. 36:1145–1147.</ref><ref>USDA Forest Service (1938). "White spruce on alkaline soils." USDA, For. Serv., Lake States For. Exp. Sta., St. Paul MN, Tech. Note 134. 1 p.</ref> 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.<ref name="SilvicsNA" /> Chlorosis was observed in young white spruce in heavily limed nursery soils at about pH 8.3.<ref name="nien1" /> Wilde<ref name="wilde3" /> 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.<ref name="sutton" /> Alluvium on the floodplains of northern rivers shows pH levels from 5.0 to 8.2.<ref name="zasada">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.</ref> High-lime ecotypes may exist,<ref name="pell">Pelletier, J.R. (1966). "Tree breeding in Canada." Commonw. For. Rev. 45(1):9–10.</ref> 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,<ref name="rowe" /><ref name="sti">Stiell, W.M. (1976). "White spruce: artificial regeneration in Canada." Dep. Environ., Can. For. Serv., Ottawa ON, Inf. Rep. FMR-X-85. 275 p.</ref> while calcareous soils are favourable sites for northern outliers of white spruce.<ref name="hust1"/>
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.<ref name="laroi">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. [Nienstaedt and Zasada 1990]</ref><ref name="vier5">Viereck, E.G. (1987). Alaska’s wilderness medicines – healthful plants of the North. Alaska Publishing, Edmonds, Washington WA. 107 p. [Nienstaedt 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).<ref name="viera" /><ref name="vierb" /><ref name="gill">Gill, D. (1975). "Influence of white spruce trees on permafrost-table microtopography, Mackenzie River Delta." Can. J. Earth Sci. 12(2):263–272.</ref><ref name="vanc">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." pp. 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.</ref>
Cold hardinessEdit
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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 Template:Convert, and even lower temperatures occur in parts of the range.<ref name="SilvicsNA" /><ref name="fowells"/> Boreal Picea are among the few extremely hardy conifers in which the bud primordia are able to survive temperatures down to Template:Convert.<ref name="sakai4">Sakai, A.; Larcher, W. (Eds.) (1987). Frost Survival of Plants. Springer-Verlag, New York NY. 321 p.</ref>
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.<ref name="glerum1">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.</ref> 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.<ref name="smith">Smith, B.J. (1949). "Silvicultural work at the Sault Ste. Marie Division [of Abitibi Power and Paper Co. Ltd.]." Can. Pulp Paper Assoc., Woodlands Section, Woodlands Section Index No. 1050 (F-2). 4 p.</ref><ref>Rowe, J.S. (1955). Factors influencing white spruce reproduction in Manitoba and Saskatchewan. Can. Dep. Northern Affairs and National Resources, For. Branch, For. Res. Div., Ottawa ON, Project MS-135, Silv. Tech. Note 3. 27 p.</ref><ref>McLeod, J.W. 1964. Planting white spruce on wet brushy land. Can. Dep. For., For. Res. Branch, Ottawa ON, Publ. 1067. 4 p.</ref> This sensitivity is a major constraint affecting young trees planted without overstorey nurses in boreal climates.<ref name="sutton4">Sutton, R.F. (1992). "White spruce (Picea glauca [Moench] Voss): stagnating boreal old-field plantations unresponsive to fertilization and weed control." For. Chron. 68:249–258.</ref>
Forest successionEdit
Forest succession in its traditional sense implies two important features that resist direct examination.<ref name="solo">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.</ref> 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 human lifespan.<ref name="solo" /> 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.<ref name="jeff2"/> 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.,<ref name="van1">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.</ref> 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 [in Alaska] may 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. Heikinheimo<ref name="heik">Heikinheimo, O. 1915. Der einfluss der brandwirtschaft auf die Wälder Finnlands. Kaskiviljelyksen Vaikutus Suomen Metsin. Acta Forest. Fenn. 4:1–264, 1–149, 1–59 [German summary p 1–59]</ref><ref name="lutz">Lutz, H.J. 1956. Ecological effects of forest fires in the interior of Alaska. USDA, For. Serv., Washington DC, Tech. Bull. 1133. 121 p.</ref> found that birch ash inhibited white spruce seedlings, and Gregory<ref name="greg">Gregory, R.A. 1966. The effect of leaf litter upon establishment of white spruce beneath paper birch. For. Chron. 42:251–255.</ref> found that birch litter has a smothering effect on spruce seedlings.".<ref name="neil">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.</ref>
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 coverEdit
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.<ref name="vier1">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.</ref> 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.<ref name="vier1"/> 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 lichens. Several white spruce communities have been identified in interior Alaska: white spruce/feathermoss; white spruce/dwarf birch/feathermoss; white spruce/dwarf birch/sphagnum; white spruce/avens/moss; and white spruce/alder/bluejoint.<ref>Viereck, L.A. 1975. Forest ecology of the Alaska taiga. Circumpolar Conference on Northern Ecology, Sept. 1975, Ottawa ON. National Res. Council, Ottawa ON, Proc. I:1>–22. [Youngblood 1993; Search A abstr]</ref><ref name="vier1"/>
Of the Eastern Forest Cover Types recognized by the Society of American Foresters,<ref name="eyre" /> only one, White Spruce, names that species in its title. The eastern White Spruce Cover Type, as defined, encompasses white spruce both in pure stands, and in mixed stands "in which white spruce is the major [undefined] component."<ref name="payette1">Payette, S. 1980. Eastern forest cover types, Boreal Forest Region: white spruce. p.15 in Eyre, F.H. (Ed.). Forest Cover Types of the United States and Canada. Soc. Amer. Foresters, Washington DC. 148 p.</ref>
In most of its range, white spruce occurs more typically in association with trees of other species than in pure stands.
White spruce is an associated species in the following Eastern Forest cover types, by the Society of American Foresters; in the Boreal Forest Region: (1) jack pine, (5) balsam fir, (12) black spruce, (16) aspen, (18) paper birch, and (38) tamarack; in the Northern Forest Region: (15) red pine, (21) eastern white pine, (24) hemlock-yellow birch, (25) sugar maple-beech-yellow birch, (27) sugar maple, (30) red spruce-yellow birch, (32) red spruce, (33) red spruce-balsam fir, (37) northern white-cedar, and (39) black ash-American elm-red maple.<ref name="SilvicsNA" /><ref name="eyre">Eyre, F.H. (Ed.) 1980. Forest Cover Types of the United States and Canada. Soc. Amer. Foresters, Washington DC. 148 p.</ref>
PredatorsEdit
Outbreaks of spruce beetles have destroyed over Template:Convert of forests in Alaska.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Although sometimes described<ref name="swit">Switzer, A.L.K. (1960). "Spruce management for the future." For. Chron. 36(2):163–165.</ref> as relatively resistant to attack by insects and disease, white spruce is far from immune to depredation. Important insect pests of white spruce include the spruce budworm (Choristoneura fumiferana), the yellow-headed spruce sawfly (Pikonema alaskensis), the European spruce sawfly (Gilpinia hercyniae), the spruce bud moth (Zeiraphera canadensis),<ref name="rose"/> and spruce beetle (Dendroctonus rufipennis).<ref name="fowell">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.</ref><ref name="rose">Rose, A.H.; Lindquist, O.H. (1985). Insects of eastern spruces, fir and, hemlock, revised edition. Gov’t Can., Can. For. Serv., Ottawa, For. Tech. Rep. 23. 159 p. (cited in Coates et al. 1994, cited orig ed 1977)</ref><ref name="ives">Ives, W.G.H.; Wong, H.R. (1988). Tree and shrub insects of the prairie provinces. Gov’t Can., Can. For. Serv., Edmonton AB, Inf. Rep. NOR-X-292. 327 p.[Coates et al. 1994]</ref> As well, other budworms, sawflies, and bark beetles, gall formers, bud midges, leaf miners, aphids, leaf eaters, leaf rollers, loopers, mites, scales, weevils, borers, pitch moths, and spittlebugs cause varying degrees of damage to white spruce.<ref name="ives" />
A number of sawflies feed on spruce trees. Among them European spruce sawfly, yellow-headed spruce sawfly, green-headed spruce sawfly and the spruce webspinning sawfly.<ref name="rose" />
More than a dozen kinds of looper feed on the spruces, fir, and hemlock in eastern Canada. The full-grown larvae of the larvae vary in length from 15 mm to 35 mm. Some feed briefly in the fall and complete their feeding in the spring; others feed mainly in the summer; still others feed mainly in the late summer and fall.
The fall and spring feeding group includes the dash-lined looper (Protoboarmia porcelaria indicataria), the diamond-backed looper (Hypagyrtis piniata), the fringed looper (Campaea perlata), and the false loopers (Syngrapha species). The summer feeding group includes the false hemlock looper (Nepytia canosaria Walker), occasionally occurring in large numbers and usually in conjunction with the hemlock looper (Lambdina fiscellaria), the Eupithecia species, the yellowlined conifer looper (Cladara limitaria), and the saddleback looper (Ectropis crepuscularia).
The late summer and fall group includes the common spruce-fir looper (Semiothisa signaria dispuncta) and the similar hemlock angle (moth) Macaria fissinotata on hemlock, the small spruce loopers Eupithecia species, the gray spruce looper Caripeta divisata, occasionally abundant, the black-dashed hydriomena moth (Hydriomena divisaria), and the whitelined looper (Eufidonia notataria).
CultivarsEdit
Numerous cultivars of various sizes, colours and shapes have been selected for use in parks and gardens. The following have gained the Royal Horticultural Society's Award of Garden Merit.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
- Picea glauca 'Echiniformis'<ref>{{#invoke:citation/CS1|citation
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- Picea glauca var. albertiana 'Alberta Globe'<ref>{{#invoke:citation/CS1|citation
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- Picea glauca var. albertiana 'Conica'<ref>{{#invoke:citation/CS1|citation
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'Conica' is a dwarf conifer with very slender leaves, like those normally found only on one-year-old seedlings, and very slow growth, typically only Template:Convert per year. Older specimens commonly 'revert', developing normal adult foliage and starting to grow much faster; this 'reverted' growth must be pruned if the plant is to be kept dwarf.
UsesEdit
The wood of white spruce is of a lower quality than that of Engelmann spruce, but is stronger. It was used to make shelters and as firewood by Native Americans and European settlers in Alaska, where lodgepole pine does not grow.<ref name=":02">Template:Cite book</ref> The wood is of major economic importance in Canada, being harvested for paper and construction. It is also used as a Christmas tree.
The wood is also exported to Japan where, known as "shin-kaya", it is used to make go boards as a substitute for the rare kaya wood. Additionally, Picea glauca var. densata is used for bonsai.
White spruce is the provincial tree of Manitoba<ref>Template:Cite book</ref> and the state tree of South Dakota.
The new growth or tips of white spruce is used in beer making,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> gin production,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> flavouring soda,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> candy making or in pickles and preserves.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>