Cone and seed production: Black spruce has the smallest seeds of North
American spruces, averaging 404,000 per pound (890,000/kg) . Trees
can begin producing seed when as young as 10 years old but generally do
not produce seed in quantity until they are 30 years old or older .
Some seed is produced every year, and bumper crops are produced 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. Annual seedfall in mature black spruce stands has been
reported at [29,65]:
200,000 seeds/acre (494,000/ha) in Minnesota
990,000-1,692,000 seeds/acre (2.45-4.2 million/ha) in Ontario
404,000-1,900,000 seeds/acre (1.0-4.9 million/ha) in ne Ontario
240,000-528,000 seeds/acre (590,000-1,300,000/ha) near Inuvik, NWT
344,000 seeds/acre (850,000/ha) in central Alaska
Dispersal: Black spruce cones are semi-serotinous. They remain
partially closed and disperse seed over a period of several years. In
Minnesota, cones release about 50 percent of their seeds within 1 year
after ripening, and about 85 percent within 5 years . In
northeastern Ontario, cones contained about one-half of their seeds
after 5 years ; however, another study in Ontario found that after 3
years, cones retained only about 2 percent of their seeds . Some of
this variation is probably related to weather, as cones tend to open in
warm, dry weather but remain closed in cold, wet weather .
Dispersal occurs throughout the year but is greatest in the winter and
spring and lowest in the fall . In northeastern Ontario, 58 percent
of annual seedfall is dispersed in March, April, and May . In
Minnesota, annual seedfall was: 9 percent in August, 19 percent in
September, 38 percent from October through April, 13 percent in May, 14
percent in June, and 7 percent in July . Most seed is dispersed
within about 264 feet (80 m) of a source .
Viability: Germinative capacity of recently ripened seed is high, about
88 percent . Viability decreases with age. In northeastern
Ontario viability of filled seed averaged 53 percent for 1- to
5-year-old seed, 20 percent for 6- to 10-year-old seed, and 5 percent
for 11- to 15-year-old seed .
Germination and seedling establishment: Black spruce seeds will
germinate and establish on numerous substrates if the seedbed remains
moist but not saturated, and free of competing vegetation .
Seedling establishment is best on mineral soils, sphagnum mosses, and
rotten wood [16,65]. Seeds readily germinate on sphagnum mosses,
probably because they are continually moist; however, seedlings are
often overtopped and engulfed by the fast-growing sphagnums .
Feather mosses provide a poor seedbed because they have a tendency to
dry out, but black spruce can establish in feather moss during wet
Growth: Seedlings are shade tolerant, but growth is fastest in full
sunlight . Seedlings rarely grow more than 1 inch (2.5 cm) in their
first growing season. Three-year-old seedlings are commonly 3 to 5
inches tall . Roots of 1st-year seedlings may penetrate to 2 inches
(5 cm) on upland soils, but when growing in mosses roots rarely reach
depths of 1.5 inches (3.8 cm) after two growing seasons .
Vegetative reproduction: Layering occurs when black spruce's lower
branches become covered with mosses or litter. It is particularly common
in swamps, bogs, and muskegs. At the northern limit of trees across
Alaska and northern Canada, black spruce reproduces almost entirely
through layering . Seeds may be produced, but few if any are
- 16. Curtis, John T. 1959. The vegetation of Wisconsin. Madison, WI: The University of Wisconsin Press. 657 p. 
- 19. Elliott, Deborah L. 1979. The current regenerative capacity of the northern Canadian trees, Keewatin, N.W.T., Canada: some preliminary observations. Arctic and Alpine Research. 11(2): 243-251. 
- 27. Fowells, H. A., compiler. 1965. Silvics of forest trees of the United States. Agric. Handb. 271. Washington, DC: U.S. Department of Agriculture, Forest Service. 762 p. 
- 29. Haavisto, V. F. 1975. Peatland black spruce seed production and dispersal in northeastern Ontario. In: Fraser, J. W.; Jeglum, J. K.; Ketcheson, D. E.; [and others]
- 36. Tuskan, Gerald A.; Laughlin, Kevin. 1991. Windbreak species performance and management practices as reported by Montana and North Dakota landowners. Journal of Soil and Water Conservation. 46(3): 225-228. 
- 37. Johnston, William F. 1977. Manager's handbook for black spruce in the North Central States. Gen. Tech. Rep. NC-34. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 18 p. 
- 55. Safford, L. O. 1974. Picea A. Dietr. spruce. In: Schopmeyer, C. S., ed. Seeds of woody plants in the United States. Agric. Handb. 450. Washington, DC: U.S. Department of Agriculture, Forest Service: 587-597. 
- 65. Viereck, Leslie A.; Johnston, William F. 1990. Picea mariana (Mill.) B.S.P. black spruce. In: Burns, Russell M.; Honkala, Barbara H., technical coordinators. Silvics of North America. Volume 1. Conifers. Agric. Handb. 654. Washington, DC: U.S. Department of Agriculture, Forest Service: 227-237. 
- 68. Wilton, W. C. 1963. Black spruce seedfall immediately following fire. Forestry Chronicle. 39(4): 477-478. 
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