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Minnesota’s tamarack forest type

Products and Uses

Tamarack (eastern larch, Larix laricina) is used for pulp, poles, and lumber, although it has relatively minor economic importance. Red squirrel, snowshoe hare, and porcupine are found in tamarack stands. Tamarack is habitat for many songbirds and is critical habitat for the great gray owl and its small mammal prey species.

Tamarack can be found in pure stands, but is more common in mixedClick for a better view. stands primarily with black spruce. Other species that can be found mixed with tamarack include northern white-cedar, black ash, red maple, eastern white pine and/or paper birch.

Tamarack commonly grows on bogs or peatland where the organic soil or peat is more than 12 inches thick. It occurs on a wide range of peatlands, but is most characteristic of poor swamps where soil water is weakly enriched with mineral nutrients. The best sites are upland sites, or moist well-drained loamy soils along streams, lakes, or swamps, and mineral soils with a shallow surface layer of organic matter. Often tamarack is quickly eliminated from these sites by competition from more shade-tolerant species. Because of this, we find tamarack in the wetlands of Minnesota which are not tolerated by other species. although they are tolerant of wet sites tamarack will not survive prolonged flooding.

Regeneration

The regeneration system advised for tamarack is a combination of clearing and seed-tree with natural seeding. Good seed years occur every 3 to 6 years starting when trees are about 40 years old. The best seedbed is a warm,moist mineral or organic soil with no brush, but a light cover of grass or other herbaceous vegetation. Hummocks of slow-growing sphagnum moss often make a good seedbed. Most seed falls within 200 feet of the seed tree.

Click for a better view.Harvest strips should be oriented perpendicular to the wind and may be up to 200 feet wide. After clearing the first strip, wait about 10 years or until the area is well stocked with seedlings, then clear a second strip adjacent to the first and on the windward side. Again wait until regeneration is established, then use the seed-tree method to cut the remaining strip. The seed-tree cut should leave about ten well-spaced dominant tamaracks per acre. Once the regeneration is established, harvest or kill seed trees to eliminate competition and possible hosts for disease.

map showing range of tamarack
Range of tamarack.

You may need to prepare the site following a harvest to assure tamarack regeneration. Broadcast burn mixed species stands to remove slash. Since tamarack slash does not burn well, harvest pure tamarack stands by full-tree skidding to remove slash, then treat the brush with herbicides. Alternatively, you could pile and burn the slash or shear or chop the brush.

Tamarack seedlings need abundant light and constant moisture. Seedlings established under a fully stocked stand will not survive beyond the sixth year. Early seedling losses are caused by damping-off fungus, drought, flooding, inadequate light, and snowshoe hares. Given enough light, tamarack is one of the fastest growing conifers on upland sites.

Intermediate Treatments

Thinning is economically feasible only on good sites when the object is to produce poles or sawtimber. If a market exists for small products such as posts or pulpwood, make a commercial thinning as soon as the stand produces these products. Additional periodic thinnings are recommended up to 20 years before the end of the rotation. Each thinning should leave a basal area of 80 to 90 squareClick for a better view.feet per acre.

Pests

The larch sawfly is a serious insect pest of tamarack, which after several years of defoliation can stress and eventually kill a tree. Many forms of chemical control are available and may be required to manage sawfly populations depending on the severity of the outbreak. There is no effective cultural control for sawfly, but as with all defoliating insects it is important to maintain healthy trees to minimize the stress caused by defoliation. Bark beetles can also kill tamaracks stressed by defoliation or competition in densely stocked stands. Tamarack also is susceptible to root and heart rots. Minimize rots by avoiding damage to the base and roots of trees during intermediate cuttings. Porcupines also have the ability to cause extensive damage to tamaracks by feeding on the bark of the main stem.

This content is modified from the 2009 book Woodland Stewardship: A practical guide for Midwestern landowners, 2nd Ed. Click here for more about the book, including ordering information.

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Mel Baughman

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