Forest Types
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Aspen   Bur Oak   Northern White-Cedar
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Jack Pine

| Description | Products and Uses | Site Conditions |
| Regeneration | Immediate Treatments | Pests and Diseases |

Description

Range of quaking aspen Jack pine (Figure 6-11) usually grows in pure stands, but may be mixed with northern pin oak, red pine, quaking aspen, paper birch, and balsam fir. On moist sites in the northern Lake States, jack pine may succeed to red pine to eastern white pine to hardwoods (such as sugar maple, basswood, and northern red oak).

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Products and Uses

Jack pine is used mainly for pulpwood, poles, and small sawlogs. It is moderately useful deer browse. Dense, young stands provide cover for snowshoe hares. Dense sapling and poletimber stands offer some wildlife shelter, but not as much as most other conifers. The Kirtland?fs warbler, an endangered species of bird that nests only in Michigan, requires homogeneous jack pine stands that cover more than 80 acres and and have trees that are 5 to 20 feet tall with branches that reach the ground. Older jack pine stands usually are less dense than other conifer stands, permitting the growth of understory shrubs and herbaceous plants that provide food and cover for wildlife.

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Pure stand of jack pineSite Conditions

Jack pine commonly grows on level to gently rolling sand plains. It occurs less commonly on eskers, sand dunes, rock outcrops, and bald rock ridges. It grows best on well-drained loamy sands where the midsummer water table is 4 to 6 feet below the surface. Jack pine does well on moderately acidic soils, but it will tolerate slightly alkaline conditions. It grows poorly on shallow bedrock and heavy clay soil. Jack pine survives and grows better than other tree species on dry sandy soils. On better sites, convert the stand to species that are more productive and valuable for wood products. Site index curves for jack pine are shown in Appendix B-9.

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Regeneration

Although jack pine is short-lived, stands sometimes survive for 100 years. Plan a rotation age of 40 to 50 years for pulpwood and 60 to 70 years for poles and sawtimber. Mature trees range from 8 to 12 inches DBH.

Jack pine needles and conesJack pines typically begin producing seeds when they are 5 to 10 years old under open-crown conditions, but later when growing in dense stands. The best seed production occurs in trees that are 40 to 50 years old. Seed production is fairly regular and increases until crown competition becomes a factor. Some seed is usually produced every year and total crop failures are rare. Jack pine cones in parts of the range are serotinous–that is, they remain closed at maturity. Serotinous cones open most readily during dry weather when the temperature is at least 80° F, although many remain closed until they are exposed to fire or high temperatures (122° F) near the ground after wind breakage or logging. Nonserotinous cones may disseminate seeds during any season. Jack pine seeds are dispersed by wind about two tree heights.

Seedling survival is highest on mineral soil and burned seedbeds where competition from other vegetation is not severe, the water table is high, and there is light shade primarily from scattered slash. Heavy slash must be reduced by full-tree skidding, burning with a hot fire, chopping, disking, or dragging. Shrubs and other competition can be controlled by full-tree skidding, machine scalping, disking, roller-chopping, bulldozing, shearing, rock or root raking, or using herbicides. Clearcutting creates the best conditions for regeneration, but seed tree or shelterwood systems may be appropriate depending on the stand and site conditions.

Clearcut where a new stand will be established by planting improved seedlings, direct seeding, or scattering serotinous cones from high-quality trees. The sun?fs heat near the ground surface will open serotinous cones and release the seed. If the mature stand is not a suitable seed source, burn the site to destroy slash and plant or seed the area using a desirable seed source.

The seed-tree system may work satisfactorily where you have 10 well-distributed, desirable quality seed trees an acre with an abundant supply of nonserotinous cones. After the harvest, burn the area to consume slash, kill competition, and prepare a favorable seedbed. Burn slash as soon as possible after harvest to minimize the risk of seed trees windthrowing before they cast seed. Jack pine slash requires a month of warm, dry weather to cure sufficiently to burn. Early spring fires permit seeding during the most favorable season, but late fall burning and seeding may be almost as effective if rodent populations are low.

Consider the shelterwood system in well-stocked stands with nonserotinous cones. Treat competition and slash as described earlier. Cut the stand to leave 30 to 40 square feet of basal area an acre in desirable seed trees. Remove the shelterwood overstory when there are 600 seedlings an acre or within 10 years.

Direct seeding in early spring may be successful where the water table is within a few feet of the surface or there is frequent precipitation during germination and early seedling development. Coat the seed with bird and rodent repellents and sow it at the rate of 20,000 viable seeds an acre.

Where direct seeding has failed, or on deep, dry sandy soils, plant bare-root seedlings in spring or container-grown stock into early summer. Plant at a 6- to 8-foot spacing.

Jack pine is a pioneer type on nearly all sites except dry, sandy soils. On better sites facilitate the successional trend by harvesting jack pines in several cuts to encourage the growth of other species, or clearcut and plant another species, usually red pine or white spruce, depending on the site.

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Intermediate Treatments

This jack pine stand needs thinningJack pine is very intolerant of shade. On better sites with substantial hardwood competition, control brush with herbicides when it threatens to overtop jack pines.

Most natural jack pine stands are understocked. To prevent stagnation in dense seedling and sapling stands with more than 2,000 trees an acre, weed out undesirable trees, leaving 800 to 1,000 uniformly spaced crop trees. In very dense seedling stands (for example, with 10,000 trees an acre) it is less expensive to mechanically clear strips about 8 feet wide and leave strips about 2 feet wide. On good sites (with a site index of 60 or more) where sawtimber is desired, thin pole-sized stands to 80 square feet of basal area an acre or follow the stocking chart in Appendix C-4 on page 209. Do not remove more than one-third of the basal area during any one thinning. Pruning is not recommended.

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Pests and Diseases

Common insect pests of jack pine include bark beetles and jack pine budworm. Stem rusts, heart rot, root rot, and stem cankers are important diseases. Fire damages trees of all sizes. Deer browsing, snowshoe hare girdling, and porcupine bark stripping may cause significant mortality when animal populations are high.

Drought and injuries increase losses to insects and diseases. To minimize pest problems, keep stands growing vigorously. Thin regularly, removing suppressed and low-vigor trees while avoiding damage to residual trees. Harvest stands by age 50 (or by age 70 where the site index is greater than 70). Do not reproduce jack pine where the site index is less than 55.

To avoid bark beetle damage, do not harvest or thin the stand from January through August unless you destroy all slash greater than two inches in diameter within three weeks of cutting. Destroy the slash by piling and burning, chipping, or burying. Avoid wounding trees during thinning. If trees are damaged by fire, windstorms, or logging, harvest them, remove the logs from the woodland, and destroy the slash within three weeks.

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