Note: Numbers given in square brackets in the text refer to the images presented above; image numbers are displayed to the lower left of each image.

General: A long-lived evergreen tree (100–200 years old), 18–25 m tall, with a d.b.h. of 40–75 cm in Canada (Roberts and Mallik 1994, Farrar 1995) [1–5]. Red pine is a moderately deep-rooted, windfirm, shade-intolerant species adapted to germination after fire (Rudolf 1990); it grows primarily on dry sandy or gravelly sites, and its seed germinates best where the mineral soil is partially exposed. Due to its adaptations to growth after fire and its low shade-intolerance, which is comparable to that of black ash (Fraxinus nigra), red pine usually grows in even-aged stands (Rudolf 1990). Beginning in the early 1900s, red pine was commercially harvested for railway ties and structural timber in northeastern Central Newfoundland, when its historic range was broader than the current range of only 22 known stands in Central Newfoundland. (Roberts 1985, Roberts and Bajzak 1996). Due to its current limited distribution on the Island, there is now a ban on commercial and domestic harvesting of red pine (Model Forest of Newfoundland 2011). Red squirrels are reported to eat the seeds of red pine (Dept. of Environment and Conservation 2015).

Key Features: 

1. Needles occur in fascicles of 2; the fascicle sheath is persistent [6].
2. Needles are 7–17 cm long, stiff, brittle, and semicircular in cross-section [7].
3. Seed cones are short, 4–7 cm long, ovoid, and symmetrical [8].

Red pine is classified as a hard pine (subgenus Pinus). In addition to the needle traits listed above, red pine shares the following traits of hard pines: needles have 2 vascular bundles, stomata occur on all needle surfaces, cones are sessile, cone scales have a central but depressed umbo on each apophysis, cone scales are sealed shut by resin after fertilization, and the wood is high in density, with an abrupt transition from earlywood to latewood.

Stems/twigs: Twigs are orangish to reddish-brown and glabrous, but rough due to the presence of persistent bracts that remain after needles have fallen; buds are narrowly ovoid, to 2 cm long, scaly, resinous, and sharply pointed (acuminate) [9–10]. Trunks are usually very straight with most branches of mature trees occurring in the broad crown [1–2]; branching is often whorled, most noticeable in younger trees [5]. The bark on mature trunks is scaly and pale reddish-brown to greyish [11]; older trunks have furrowed bark with flat scaly greyish-brown ridges [12].

Needles: Evergreen, simple, sessile, and in fascicles of 2 needles [6–7]. Red pine needles are 7–17 cm long, narrow, straight, dark green, pointed (acute) at the apex, and brittle when bent in half (often snapping in half when bent). Needles are semicircular in cross section (flat on one surface, rounded on the opposite surface) and have finely serrulate margins. Each fascicle is bound at the base by a tubular sheath, 1–2.5 cm long, composed of overlapping rows of persistent transparent bracts. The sheath bracts are pale golden-yellow on emerging needles, but become silvery grey on fully expanded needles [10]. Fascicles are subtended by spreading to reflexed triangular bracts that persists on the twig after needles have dropped [6].

Reproductive structures/cones: Unisexual; trees monoecious, with separate male and female cones on different branches of the same tree. Male cones are ellipsoid, reddish-brown to yellow, with many cones clustered at the base of new growth [13–15]; male cones are shed after pollen is released; pollination is by wind (anemophily). Immature female cones (conelets) are ellipsoid, reddish-purple, erect, and terminal on new shoots [16–17]. Cone scales of immature cones open in spring during pollination, then close tightly until the end of the 2nd growing season, when seeds are mature. One-year-old cones are ovoid; each cone scale terminates in a smooth light brown diamond-shaped end (apophysis) with a central depressed umbo; each apophysis is bordered in white and surrounded by a broader black resinous border [17]; mature cones [18–20] are light brown, broadly ovate, sessile, and 4–7 cm long. Two full growing seasons are required for red pine seed cones to mature, thus cones in 3 stages of development may be present on the branches [21]. Seeds are about 5 mm long with a thin wing, to 15 mm long; seeds are shed from cones in late autumn of their second year. Seed cones usually detach from the tree during the year following seed dispersal.

Ecology & Habitat: Red pine has a very limited distribution in the province, occurring on 22 sites, mostly in the Central Newfoundland Ecoregion (Roberts 1985, Roberts and Bajzak 1996, Damman 1976). It occurs on very dry nutrient-poor sites, usually on shallow soils, sands, and gravels. Red pine is less shade-tolerant than its primary competitor, black spruce, and requires fire to create the light and seedbed conditions necessary for its survival. The limited distribution of red pine may be due to a combination of high July maximum temperatures, low precipitation, very dry soil, and high fire frequency, which historically allowed it to out-compete black spruce.

Depending on the degree of crown closure, the understorey of red pine forests can be variable. In open and early successional stands, species adapted to nutrient-poor, dry soils are abundant [22], including bracken fern, sheep laurel, Labrador tea, rhodora, lowbush blueberry, and pink moccasin flower. In dense, mature forests and overstocked conifer plantations, light conditions in the understorey may totally eliminate shrubs and herbs, and leads to self-pruning of lower branches [23], which promotes a ground cover of only pine needles and dead branches [24].

Genetic studies have concluded that Newfoundland populations of red pine are undifferentiated from mainland populations (Mosseler et al. 1991). Due to its scarcity in the province, the 865 ha West Brook Ecological Reserve was established in 1999 to protect red pine under the provincial Wilderness and Ecological Reserve Act.

Edaphic Grid: See image [25]: the Edaphic Grid for Pinus resinosa.

Forest Types: Red pine has been described from only two subassociations:

• Kalmio-Piceetum cladonietosum (Cladonia-Kalmia-Black Spruce Forest Subassociation)
• Kalmio-Piceetum typicum (Kalmia-Black Spruce Forest Subassociation)

Succession: Red pine does not reproduce vegetatively and is therefore dependant on seed dispersal and seedling establishment for stand renewal. Seed dispersal can exceed 200 m, but most seeds fall within 12 m of the parent tree. A scarified seedbed is needed for successful germination, but the excessively droughty conditions of the site increase the risk of seedling mortality. Red pine is very shade intolerant and therefore dependant on fire to reduce vegetation competition. Mature trees have thick bark and can survive fire, but long-term fire suppression policies have probably favoured the replacement of red pine by black spruce and balsam fir.

Distribution: Red pine has a very localized distribution in central Newfoundland (Roberts 1985, Roberts and Bajzak 1996). In mainland Canada, it occurs from Cape Breton Island, Nova Scotia, to southeastern Manitoba. It the United States, red pine's main range extends south from Maine to northern Pennsylvania, and west to northeastern Minnesota (Rudolf 1991).

Similar Species: Red pine is most similar in stature, habitat, and needle length to white pine (Pinus strobus L.), but white pine has 5 needles per fascicle and its cones are cylindrical and narrow, 8–20 cm long, green when immature, and brown at maturity. Like red pine, jack pine (Pinus banksiana Lamb.) is a fire-adapted species with only 2 needles per fascicle, but jack pine needles are stiff and much shorter, 2–5 cm long. Jack pine cones are light brown, short, 3–5.5 cm long, and often curved or asymmetric.