Managing eastern white pine forests
- White pine is most common on well-drained, sandy soils. The worst soils for white pine are clay or poorly drained.
- Rotations may be as long as 120 years for white pine, but 80 years is usually enough to produce sawlogs on good sites.
- Regenerating white pine under an existing canopy is often a good idea.
- Do not plant white pine in high-hazard zones for blister rust.
- Use bud caps to prevent deer from eating the buds of young white pine.
Eastern white pine is mainly used for lumber.
Unlike red pine, white pine tends to have a better-developed tall shrub (less than 10 feet) and herb layers (less than 3 feet), except in pure, dense stands. This provides wildlife habitat.
While wildlife may use young, dense stands for shelter during bad weather, they receive virtually no food benefit from older white pine stands. Deer and rabbits feed heavily on white pine seedlings.
- White pine is most common on well-drained, sandy soils where it competes well with hardwoods.
- White pine also grows well on soils mixed with sand, silt and clay with good or impeded drainage.
- But on these soils, it usually cannot compete with more aggressive hardwoods.
- The worst soils for white pine are clay or poorly drained.
- Direction and angle of slope rarely restrict white pine.
- You will find them on a variety of slopes, regardless of how steep they are or which direction they are facing.
- Compared to many pines that cannot tolerate shade, white pine is intermediate in shade tolerance, and may live 200 years or more.
- Seed production is generally good every three to five years.
- If there is cone beetle damage, you may go 10 years or longer without a good seed crop.
Regenerating white pine
White pine naturally reproduces from seed. Seeds will disperse at least 200 feet within a pine stand and more than 700 feet in the open.
Seedlings grow best under partial shade. Seedlings require at least 20 percent of full sunlight to survive. If there is full sunlight, they may die from high soil surface temperature.
A rotation is the number of years required to establish and grow trees to a desired size, product or maturity.
Rotations may be as long as 120 years for white pine, but 80 years is usually enough to produce sawlogs on good sites.
Regenerating white pine under an existing canopy is often a good idea. White pine seedlings tolerate shade well, plus this will reduce blister rust risk. You can do this by partially removing the existing canopy, to allow sufficient light for white pine seedlings to thrive. The photo below depicts this approach.
A two-cut shelterwood system is probably the most reliable method for naturally regenerating white pine.
- During the first cut, remove 40 to 60 percent of the overstory.
- Harvest during snowless months to churn the ground surface and expose mineral soil.
- Remove any hardwood trees in the stand to reduce competition with pine seedlings.
If white pine seedlings are abundant after five to 10 years, clear-cut the residual overstory. If you expect white pine weevil to be a problem, delay this harvest until the new white pines are 20 to 25 feet tall.
If white pine regeneration is not satisfactory, you may need to:
- Thin the overstory again.
- Control competing hardwood seedlings.
- Wait another five to 10 years before the final harvest.
Consider planting white pine seedlings to increase the density to 500 to 600 seedlings per acre.
You need to plant trees appropriately if you are working with bare land or white pine stands that do not naturally regenerate.
Plant 2-0 or 3-0 seedlings (seedlings grown for two to three years at a nursery without transplanting) at rates up to 600 to 800 trees per acre.
If you expect heavy white pine weevil damage, plant seedlings closer together. Plant under a light forest canopy to reduce weevil and white pine blister rust damage.
You do not need to thin white pine seedling and sapling stands. But, if a hardwood overstory develops, partially remove it to maintain 50 percent of full sunlight on the white pine.
When trees reach a certain size, your forester may recommend thinning the stand by removing any hardwoods and some of the pine to allow enough sunlight to reach the forest floor.
Maintain at least a 35 percent live crown ratio on crop trees. This ratio is the percent of a tree’s total height that has foliage.
Because white pine branches do not self-prune, you will need to prune to a height of 17 feet to reduce the size of knots and develop clear wood. Prune in the dormant season, removing limbs only if they are less than 2 inches in diameter.
Frequent light prunings are preferred to a single heavy pruning. Depending on the local market, it might not be economical to prune.
Your local forester can advise you on the blister rust hazard in your area. Do not plant white pine in high-hazard zones. In medium- and low-hazard zones, prune lower branches early to minimize the disease.
You can reduce blister rust and pine weevil damage by regenerating white pines under an overstory of hardwoods and slowly releasing them until the pines are about 20 to 25 feet tall. Then, remove the overstory.
To avoid bark beetle damage, follow these guidelines:
- If you thin or cut in the winter or early spring, remove logs and slash before June 1.
- If you thin or cut in the summer, remove logs and slash within three weeks.
- Remove or destroy woody debris greater than three inches in diameter.
- Avoid wounding trees during thinning and harvesting operations.
- Avoid wounding residual trees during thinning.
Pine sawflies are common defoliators on white pine, but usually do not cause serious damage. If you need to control them, it will require chemical sprays because microbial insecticides are not effective.
In the winter, deer will often eat the buds of young white pine. This often results in non-linear tree growth, reducing the tree’s financial value.
A simple solution is to use bud caps. By stapling a small piece of paper around bud clusters, woodland managers can protect young pines from deer.
Reviewed in 2018