White pine can grow on a relatively wide range of soils but is most commonly found on well drained and coarse-textured soils, rock outcrops, or sandy ridges. This adaptability is partly due to its deep and expansive root system, which enhances its water and nutrient uptake.
White pine has adapted to low intensity fires (Figure 2) occurring at short intervals and high-intensity fires at longer intervals to regenerate. Adult white pine trees have thick, insulating bark that allows some trees to survive low- to moderate-intensity fires. Surviving trees provide a source of seed to regenerate white pine.
Figure 2. Wildfires naturally maintain white pine forests. (Photo: F. Pinto)
The greatest chance for new white pine trees to establish occurs when there is a combination of abundant seeds, good seed beds, and reduced competition from other plants. In more northerly areas, white pine trees produce large quantities of seed every three to ten years. Fire creates forest floor conditions suitable for seed germination and removes vegetation that competes with white pine seedlings. Adult white pine trees that survive fires also provide shade that minimizes drying of seed beds and improves germination and early seedling establishment.
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| Figure 3. White pine trees can grow to be very tall. (Photo: C. Latremouille) |
During their first five years, young white pine seedlings grow slowly and do well under shade created by taller trees. However, they require more sunlight as they grow older. For this reason, forests dominated by white pine require disturbances such as low-intensity fires that increase light in the forest understory enough to allow young white pine trees to replace older white pines that die from old age. Where white pine only makes up a minor portion of the forest, small disturbances, such as wind, which remove single trees or small groups of trees sometimes provide suitable conditions for white pine to establish and grow.
White pine trees can live for up to 450 years and may grow to 1.5 metres in diameter and 50 metres in height on fertile sites (Figure 3). However, trees of this size are uncommon.
White pine is important to many species of wildlife. White pine seeds are a valuable food source for birds and small mammals. The dead tops of some older supercanopy trees, which grow to be taller than other trees in the forest, are favoured by bald eagles and ospreys for nesting. Hollow supercanopy white pine trees also provide denning sites for black bears.
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