Pinus banksiana

Jack Pine

Pinus banksiana, Jack Pine

Jack Pine, BWCAW
Photo © by Earl J.S. Rook

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

Name:
  • Pinus, from the Greek, pitus (pitys), "pine or fir tree"
  • banksiana, after Sir Joseph Banks (1743-1820), British naturalist and botanist on Cook's first great voyage (1768-1771); some 75 species bear Banks' name.
  • Common Name, from "Jack possibly from use of wood in making levers, jacks."
  • Other common names include Eastern Jack, Gray Pine, Black Pine, Black Jack Pine, Prince's Pine, Princess Pine, Banks Pine, Banksian Pine, Hudson Bay Pine, Scrub Pine, Northern Scrub Pine, pin gris

Taxonomy:
  • Kingdom Plantae, the Plants
    • Division Coniferophyta, the Conifers
      • Class Pinopsida
        • Order Pinales
          • Family Pinaceae, the Pines, Spruce, and Firs
            • Genus Pinus, the Pines
  • Taxonomic Serial Number: 183319
  • Also known as Pinus divaricata; Pinus sylvestris var. divaricata
  • Hybridizes with Rocky Mountain lodgepole pine (Pinus contorta var. latifolia) where their ranges overlap in central and western Canada.

Description:
  • Leaves 3/4"- 2" evergreen needles, in bundles of two.
  • Height at maturity usually 55'-65' but can attain 100' with a diameter of 25". On extremely harsh, sandy sites, is small and bushy.
  • Age. Begins showing signs of decay by age 75, but can live more than 200 years. A 243-year-old jack has been found in the BWCA.
  • Roots of mature trees may penetrate to 9' though the abundant lateral roots are mostly confined to the upper 18" of soil; develops a taproot as a seedling and maintains it to maturity.
  • Cones resinous and closed.

Identification:
  • The smallest of the three native pines.
  • Distinguished from White Pine (Pinus strobus) by having needles in clusters of two.
  • Distinguished from Red Pine (Pinus resinosa) by its shorter needles and smaller cones.

Distribution:
  • Canada and the north-central and northeastern United States.

Habitat:
  • Establishes after fire in boreal forests, tundra transition areas, dry flats and hills, and on sandy soils; it also occurs on sand dunes, rock outcrops, bald rock ridges, and lake shores.
  • Usually grows in dry, acidic sandy soils with a lower pH limit of 4.0, but also loamy soil, thin soil over bedrock, peat, and soil over permafrost. Does not usually grow in moderately alkaline soil, but can grow in calcareous soils up to pH 8.2 if normal mycorrhizal fungi are present.
  • Begins to show signs of decadence by age 75, decreases in frequency by 150 years, and may disappear completely after 200, although some relic jack pine survive nearly 250 years.
  • Succeeded in the absence of fire by longer lived species such as Red Pine (Pinus resinosa) or White Pine (Pinus strobus), or by more shade-tolerant species such as Balsam Fir (Abies balsamea) and Black Spruce (Picea mariana). Black Spruce, which often seeds in at the same time as Jack Pine, grows slower but lives longer, becoming codominant after 90 years, eventually succeeding Jack Pine. On the driest, harshest sites, Jack Pine may persist as climax species.
  • One of the least shade-tolerant trees in its native range; only aspens, Paper Birch, and Tamarack are less tolerant.
  • Dominant tree in southern boreal forest. Associates are almost always subdominant except for Aspen (Populus spp.), Paper Birch (Betula papyrifera), and Red Pine (Pinus resinosa) which may be codominant.
  • Insects:
    • Root borers, root feeders, shoot and stem borers, leaf feeders, needle miners, and sucking insects affect the survival and growth of seedlings. Many other insects feed on cones. Young stands susceptible to defoliation by the Redheaded Pine Sawfly (Neodiprion lecontei).
    • Jack Pine Budworm (Choristoneura pinus) defoliates mature trees. There is often a 20-30 year lag after major fire before the budworm invades. The regenerated stand does not produce abundant cones on average for about 20 years and the budworm population thrives in years of abundant cone production.
  • Disease: susceptible to many diseases including rust fungi

Fire:
  • Best adapted of all boreal conifers to fire. With medium thick bark, mature individuals have only moderate fire tolerance, but populations survive because of delayed seed release from serotinous cones, early reproductive maturity, fast growth in full sun, and preference for mineral soil seedbeds.
  • Fire intervals generally less than 50 years. Based on fire scars, the shortest and longest times between major fires in Jack Pine forests of northern Ontario were 5 and 30 years. Major stand-replacing fires in the BWCA often occur in years of summer drought.
  • Accumulation of litter and debris on the forest floor over time increases the likelihood of moderate or severe fire. A lichen mat, a highly flammable and continuous fuel source at ground level, develops within 40 years and is important in supporting fires in Jack Pine forests.
  • Mature individuals survive low-severity fires. Jack Pine is typically killed by crown fires or by moderate-severity surface fires. Double fire scars are fairly common, but triple fire scars are rare, suggesting that an individual tree may survive only one or two surface fires in a lifetime.
  • Establishment is limited primarily by the depth of organic matter and, therefore, progressively increases with greater fire severity. Regeneration is typically better after summer fires than spring fires
  • Dense, young stands are extremely susceptible to crowning wildfire which is hard to control.

Associates:

History:
  • Was pushed south during the last Ice Age, forming a band of Jack Pine forest from the Mississippi River valley eastward onto the Continental Shelf between northern North Carolina and Central Georgia.
  • Began leaving the southeast about 15,000 years ago, finally disappearing from Tennessee about 12,750 years ago. The returning Jack Pines arrived in Connecticutt about 12,000 years ago and entered the southern reaches of the White Spruce forest in Minnesota about 10,700 years ago, preceeding all other northbound tree species except Red Pine (Pinus resinosa). Jack was jioined by Paper Birch (Betula papyrifera) and Alder (Alnus spp.) about 1,000 years later and, with the collapse of the southern White Spruce forest, became the dominant species in our area within a few centuries time (ie, circa 7500 BCE).

Uses:
  • An important commercial timber species in the United States and Canada, the moderately hard and heavy wood is used for pulpwood, lumber, telephone poles, fence posts, mine timbers, and railroad ties.
  • Planted for Christmas trees.
  • Territorial tree of the Northwest Territories.

Reproduction:
  • Reproduces by seed.
  • Minimum seed bearing age in open stands is 5-10 years. Some seed is produced every year and serotinous cones accumulate in the crown. A mature stand may have as many as 2 million seeds per acre stored in unopened cones. Because of abundant seed production, few mature trees are necessary to regenerate a stand.
  • Cones, sealed shut by a resinous bond, require high temperatures to open. This heat is usually provided by fire, but hot, dry weather (air temperatures of at least 80 degrees F.) opens some cones.
  • The winged seeds are the smallest of the native pines and are dispersed by gravity and wind. The effective dispersal range is about 110'-130' or two tree heights.
  • Seeds usually germinate rapidly after release when the 10-day mean maximum air temperature is 65 degrees Fahrenheit or higher. Seeds occasionally exhibit partial dormancy which is probably broken naturally by heat from fire. Seeds remain viable in closed cones for years, but viability decreases over time. Up to 50% of 20-year-old seeds may be viable.
  • Exposed mineral soil or thin residual humus of about 1/4" or less provide the best seedbeds; deeper humus has an adverse effect on establishment; humus deeper than 1 1/2" is a low-quality seedbed. Successful germination and establishment usually occurs only after fire removes humus.
  • Germination and initial survival sometimes improve with partial shade, but the positive effect of shade eventually becomes negative because seedlings soon require higher light levels. Seedling survival may be low if drought conditions follow germination.
  • During its first 20 years, one of the fastest growing conifers in its range.
  • Staminate and ovulate cone primordia are initiated in late summer and then go dormant until spring. Pollen shedding usually late spring or early summer but highly dependent on the weather. Fertilization 13 months after pollination. Cones mature in late summer or early fall, 2 years after initiation.
  • Maximum growth occurrs under 43% light and higher.
  • The resin of serotinous cones melts when heated, usually at temperatures in excess of 140 degrees Fahrenheit Seed viability is not markedly affected by heating, unless the cone ignites, which kills the seed. Seeds unprotected by cones remain viable when exposed to high temperatures until the wings ash and the seed coats crack. Crown torching does not ignite cones because the high temperatures are unlikely to last more than 3 minutes.

Propagation:
  • By seed

Cultivation:
  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultural Requirements
    • Full sun
    • Well-drained, sandy loam soil, pH 4.6 - 6.5
    • Medium to dry moisture
  • Size 20'-30'W x 50'H
  • An uncommon and underutilized landscape tree.

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Last updated on 4 March, 2006