Picea mariana

Black Spruce

Picea mariana, Black Spruce

Black Spruce, Bridge Lake, BWCAW
Photo © by Earl J.S. Rook

Flora, fauna, earth, and sky...
The natural history of the northwoods

Name:
  • Picea, from the Latin for the Scotch Pine, Pinus silvestris
  • mariana, from the Latin, "of Maryland"
  • Common Name, from the dark needles
  • Other common names include Bog Spruce, Swamp Spruce, Shortleaf Black Spruce, épinette noire, Svartgreni (Is)

Taxonomy:
  • Kingdom Plantae, the Plants
    • Division Coniferophyta, the Conifers
      • Class Pinopsida
        • Order Pinales
          • Family Pinaceae, the Pines, Spruce, and Firs
            • Genus Picea - the Spruce, about 30 species from cool, temperate regions of the northern hemisphere, 7 native to North America.
  • Taxonomic Serial Number: 183302
  • Also known as Abies mariana, Picea brevifolia, Picea nigra, Pinus nigra
  • Natural hybridization between species of Picea is common. Although rare, Black and White Spruce (Picea glauca) hybrids, known as Rosendahl Spruce, have been found in northeastern Minnesota and other areas.

Description:
  • A native, coniferous, slow-growing, small upright tree or dwarf shrub with a narrow, pointed crown to 30' - 50' tall over most of its range.
  • Leaves stiff, four-sided, dark blue-green ½" needles borne on woody pegs.
  • Stem
    • Trunk straight with little taper, with 6"-10" diameter at maturity.
    • Branches short, compact, and drooping with upturned tips. A poor self-pruner, keeping dead branches for several years
    • Bark thin, scaly, and grayish brown.
  • Roots shallow and wide spreading with most in the upper 8" of organic soil. Very susceptible to windthrow except in the densest stands. Perhaps the tree species best adapted to growing on permafrost soils because of its shallow rooting habit.
  • Flowers monoecious
    • Male red, turning yellow to light brown
    • Female purple, upright, and in the upper crown
  • Fruit a ¾"-1¼" cone, smallest of the spruces; nearly round, dull grey/black, in dense clusters in the upper crown, persisting for several years.

Identification:
  • Identifiable as a spruce by its stiff, 4-sided needles.
  • Distinguished from true firs, such as Balsam (Abies balsamea), in having pendulous cones, persistent woody leaf-bases, and four-angled needles, scattered and pointing in every direction; from White Spruce (Picea glauca) in having shorter needles, smaller and rounder cones, and a preference for wetter lowland areas.
  • Field Marks
    • Very short, stiff, 4-sided evergreen needles
    • Narrow, conical form

Distribution:
  • Transcontinental; Newfoundland to Alaska, south to British Columbia, Minnesota, and east to Rhode Island and Massachusetts.

Habitat:
  • Both lowland and upland sites. At southern portion of range it is found primarily on wet organic soils, but farther north its abundance on uplands increases. In the Lake States most abundant in peat bogs and swamps, also on transitional sites between peatlands and uplands. In these areas it is rare on uplands, except in isolated areas of northern Minnesota and the Upper Peninsula of Michigan.
  • Most stands even-aged due to frequent fire intervals in Black Spruce forests.
  • Commonly grows in pure stands on organic soils and in mixed stands on mineral soils
  • Forest floor temperatures are typically lower and moisture content higher in Black Spruce forests than in Balsam Fir (Abies balsamea), Paper Birch (Betula papyrifera), White Spruce, (Picea glauca), or Quaking Aspen (Populus tremuloides) forests.
  • Soils: Tolerant of nutrient-poor soils, it is commonly found on poorly drained acidic peatlands. On Minnesota peatlands, grows best on dark brown to blackish, moderately decomposed peat that contains much partially decomposed wood. Often found on 10' of peat, and sometimes on peat 60' deep. On mineral soil in northern Minnesota and adjacent Ontario, occurs on gravel/boulder loams and shallow soils over bedrock. Black spruce usually grows on wet organic soils, but productive stands are found on a variety of soil types from deep humus through clays, loams, sands, coarse till, boulder pavements, and shallow soil mantles over bedrock. In the Lake States and adjacent Canadian provinces, it grows on soils of the order Histosols: peat bogs and swamps that have formed on old glacial lakebeds and in muck-filled seepages on peat deposits that range in thickness from 0.5 to 6 m (20 in to 20 ft). The most productive black spruce stands are on dark brown to blackish peats, which usually have a considerable amount of decayed woody material. Stands of low productivity are usually found on thick deposits of partially decomposed sphagnum peat.
  • Considered a climax species over most of its range. However, some ecologists question whether Black Spruce forests truly attain climax because fires usually occur at 50-150 year intervals, while "stable" conditions may not be attained for several hundred years.
  • The frequent fire return interval perpetuates numerous successional communities. Throughout boreal North America, Paper Birch and Quaking Aspen are successional hardwoods that frequently invade burns in Black Spruce. Black Spruce typically seeds in promptly after fire, and with the continued absence of fire, will eventually dominate the hardwoods.
  • Pioneer that invades the sedge mat in filled-lake bogs, though often preceded slightly by Tamarack (Larix laricina), with which it may in time form a stable forest cover in swamps. However, as the peat soil is gradually elevated by the accumulation of organic matter, and the fertility of the site improves, Balsam Fir and White Cedar will eventually replace Black Spruce and Tamarack.
  • Climax Black Spruce forests are widespread across boreal North America. North woods communities of which it is a part include:
  • Black Spruce-Feathermoss - Medium to dense spruce stands with a well-developed carpet of feathermosses (Pleurozium schreberi, Hylocomium splendens, Ptilium crista-castrensis). Most common at the southern and central portion of range.
  • Black Spruce-Dwarf Shrub (A variation on the Black Spruce-Feathermoss) - Closed Black Spruce stands with a well-developed dwarf shrub layer (commonly Labrador Tea (Ledum groenlandicum) in the BWCA), and forest floor dominated by mosses and reindeer lichens. Occurs in the central and southern boreal forests.
  • Black Spruce-Sphagnum Bog Forest - Open to closed pure stands on organic or wet mineral soils with well-developed dwarf shrub cover and sphagnum mosses (Sphagnum spp.) dominating the forest floor. Occurs throughout range.
  • Black Spruce-Speckled Alder (Alnus incana) - Pure or mixed stands on areas where watertable is near the surface during the growing season. Well-developed tall shrub and herbaceous layers.
  • Black Spruce-Sedge (Muskeg) - Very open stands of stunted trees on wet sites with the ground dominated by sedges and grasses and well-developed moss layers (but little or no sphagnum mosses). Widely distributed througout boreal regions.
  • Disease: Eastern Dwarf Mistletoe (Arceuthobium pusillum) most serious disease, resulting in reduced vigor, witches brooms, deformed trees, and death. Needle cast fungus also causes death in small areas. Susceptible to numerous needle rusts and fungi which bring defoliation and reduced vigor. These diseases usually remain at low levels but may become epidemic. Wind breakage arises from butt and heart rots, common in 70-100 year old upland stands and 100-130 year old stands on organic sites.
  • Insects:
    • Spruce Budworm causes defoliation and if it occurs several years in a row will lead to death, though Black Spruce is less susceptible than White Spruce, or Balsam Fir (Abies balsamea). Trees most at risk are those growing with Balsam Fir and White Spruce.
    • Monochamus Wood Borers can kill trees that border logged areas with significant residual slash.
    • European, Yellowheaded, and Greenheaded Spruce Sawflies defoliate the trees.
    • Numerous other insects attack Black Spruce but only occasionally cause serious damage.
  • Susceptible to damage from flooding and disruptions in normal groundwater movements such as road construction or beaver dams.
  • Produces seed at an early age, produces good seed crops regularly, and has persistent, semi-serotinous cones that release seed slowly over a period of years.
  • Very well adapted to growing over bedrock because of its very shallow root system.
  • The highest quality stands are found in peat bogs, swamps, and on upland stands that are underlain by clay loams. The pH of soils where the black spruce is found range from very acidic to slightly basic.

Fire:
  • Wildfires are frequent and extensive in Black Spruce forests and usually prevent the development of uneven-aged stands excepting in bogs and muskegs with longer fire-free intervals.
  • Easily killed by fire because it has thin bark and shallow roots, even by low-intensity surface fires.
  • Crowning is common because low-growing, lichen-draped branches are easily ignited by ground fires. Crown fires typically result in extensive mortality.
  • Immediately following fire, large quantities of seeds are released. Delayed seedfall and delayed germination are additional postfire adaptations which ensure that some seed is always available to germinate and establish during postfire years with favorable growing conditions. Although large amounts of seed do fall in the first postfire year, small amounts of seed will continue to be released for several years after fire.
  • Trees older than 30 years virtually always contain large amounts of seed. Following fire this large seed supply is released onto burned areas, allowing rapid seedling establishment. The seeds are usually not destroyed by fire because the cones are located in the upper part of the crown where they are least likely to burn. Even when trees are killed by fire, cones usually retain viable seed. Furthermore, the cones are small and occur in tightly compacted clusters, so that some seeds usually remain viable even after intense crown fires.

Associates:

History:
  • During the last Ice Age, a part of the vast White Spruce forests which spread across the continent, just south of the windswept tundra that bordered the great ice sheets. After White Spruce (Picea glauca), one of the earliest species to follow the retreating ice northward, reaching northeastern Minnesota about 13,000 years ago.
  • Still cut for Christmas trees, but recently the amount harvested from natural stands has declined. In the past, specialty items made from black spruce included healing salves from the gum, antiscorbutic and diuretic beverages from twigs and needles, and rope from the roots.
  • The provincial tree of Newfoundland.
  • Bill Nelson from Michigan reports, "When I was young, an old timber cruiser told me that at one time all chewing gum was made from Black Spruce. One can make it themselves by gathering the black spruce gum and putting it in a double boiler and heating it. When it becomes liquid, pore it into a shallow pan of cold water. The bugs and other impurities will flote to the top. When it hardens, pour off the water andd sprinkle some corn starch over it. Then cut it into pieces and you have some fine natural chewing gum."

Uses:
  • Wood is soft and yellowish white, relatively lightweight but strong, with long fibers that produce a very high quality pulp. The wood dries easily and is stable after drying, is moderately light in weight and easily worked, has moderate shrinkage, and is moderately strong, stiff, tough, and hard. It is not very resistant to bending or end-wise compression. It is straight, even grained, medium to fine textured, soft and produces a lustrous finish. It is without characteristic odor or taste. The wood is a pale yellowish white, and there is little difference between the heartwood and sapwood. It has exceptional resonance qualities, in the form of thin boards. It has moderately high shrinkage, but is easily air or kiln dried. It is easily worked, glues well, is average in paint holding ability, but rates low in nail holding capacity. It also rates low in decay resistance and is difficult to penetrate with preservatives. Specific gravity .38 green to .43 dry. It is easily worked, glues well, is average in paint holding ability, but rates low in nail holding capacity.
  • Principal commercial value is as pulpwood. Black spruce is the most significant species for pulpwood in Canada. Black spruce is also commercially utilized throughout the Lake States, especially in Minnesota.
  • Small stature limits use as sawtimber and it is rarely used as such. Used occasionally for lumber and a variety of specialty items.
  • Commonly used as Christmas trees, but loses its needles so soon after it has been cut.
  • Special uses of the trees leaves include distillation for perfume and as a main ingredient for spruce beer.

Reproduction:
  • Reproduces by seed and vegetatively by layering
  • Smallest seeds of North American spruces.
  • Seed Production can begin at 10 years but generally not in quantity until 30 years. Some seed is produced every year; bumper crops about every 4 years. Since seed crops seldom fail and the semi-serotinous cones release seeds over a period of several years, stands that are 40 years old or older nearly always have a continuous supply of seeds.
  • Seed Dispersal: cones are semi-resinous, remaining partially closed and dispersing seed over several years. In Minnesota, cones release about 50% of their seeds within 1 year after ripening; 85% within 5 years. Rarely, some viable seed can be found in 20 year old cones.
  • Germination and establishment: will occur on numerous substrates if the seedbed remains moist but not saturated, and free of competing vegetation. Seedling establishment best on mineral soils, sphagnum mosses, and rotten wood. Seeds readily germinate on sphagnum mosses; however, seedlings are often overtopped by the fast-growing sphagnums. Feather mosses provide a poor seedbed except during wet years due to their tendency to dry out.
  • Growth: Seedlings are shade tolerant, but growth is fastest in full sunlight. Seedlings rarely grow more than 1" in their first growing season. Three-year-old seedlings commonly 3"-5". Roots of 1st-year seedlings may penetrate to 2" on upland soils, but when growing in mosses roots rarely reach depths of 1.5" after two growing seasons.
  • Layering occurs when lower branches become covered with moss or litter; particularly common in swamps and bogs. At the northern tree limit reproduces almost entirely through layering.
  • Flowers in late May/early June. Female conelets develop rapidly and contain mature seeds about 3 months after pollination.
  • Following fire, establishes best where severe burning exposes mineral soils on upland sites or moist peat on lowland sites. Unburned or partially burned sphagnum mosses are good seedbeds, but unburned or partially burned feather mosses are poor.
  • Seeds in quickly after fire on relatively dry uplands with jack or red pine. However, the pines also seed in aggressively and quickly overtop black spruce. Black spruce is very shade tolerant and can survive in this suppressed condition for more than 100 years and, in the absence of fire, will eventually replace the pines.

Propagation:
  • By seed, germinative capacity of recently ripened seed is high, about 88%. Viability decreases with age.
  • Seeds require no stratification prior to sowing. They should be sown soon after snowmelt. On upland sites, exposing mineral soils before sowing is essential.
  • Readily propagated by root cuttings.

Cultivation:
  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultural Requirements
    • Full sun to partial shade.
    • Soil poorly drained to well drained; high in organic matter, pH 3.5-7.0.
    • Wet to medium moisture.
  • Size 15'-30'W x 40'-50'H
  • Growth rate relatively rapid after a slow-growing establishment period.
  • Cultivars include
    • "Nana", a dwarf
  • Cultivar and species available by mail order from specialty suppliers.
  • Not often planted in the landscape.

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Last updated on 4 March, 2006