Tamarack (Larix laricina): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table. A European larch also has its own page, European larch.

At a glance

Item	What the source records
Scientific name	Larix laricina (Du Roi) K. Koch, pine family; a deciduous conifer (Silvics)
Other names, Silvics	Eastern, American or Alaska larch, and hackmatack
Native status, USDA PLANTS	Native in Alaska, Canada, the lower 48 states and Saint-Pierre and Miquelon
Size and age, Silvics	Mature trees 15 to 23 m (50 to 75 ft) tall and 36 to 51 cm (14 to 20 in) in diameter; one of the largest recorded, in Maine, measures 94 cm (36.9 in) in diameter and 29 m (95 ft) tall; maximum age generally 150 to 180 years, with one 335-year-old individual found
Green weight of the wood, NRS-38	47 lb per cubic foot, without bark

Native range and sites

The Silvics of North America handbook (Agriculture Handbook 654, Volume 1, 1990) says tamarack has one of the widest ranges of all North American conifers. The main range runs from Newfoundland and Labrador west along the northern limit of trees across the Continental Divide in northern Yukon, south in the Mackenzie River drainage to northeastern British Columbia and central Alberta, and east to southern Manitoba, southern Minnesota and Wisconsin, northern Indiana and Ohio, northern Pennsylvania and New Jersey, northern Connecticut and Maine. It also grows locally in the mountains of northern West Virginia and western Maryland, and a major separate area lies in interior Alaska.

The handbook says tamarack tolerates a wide range of soils but grows most commonly on wet to moist organic soils such as sphagnum and woody peat, and is more abundant on peatlands than the trees of surrounding uplands because it withstands high soil moisture, high acidity and low soil temperature. It grows best on moist, well-drained loams along streams, lakes and swamps. In Alaska it occurs especially on bogs underlain by permafrost, and also grows well on upland loess soils. It also grows fairly well on extremely dry shallow soils, though Silvics says it can die from drought on such sites. Snowfall across the range varies from 100 cm (40 in) in the District of Mackenzie to 510 cm (200 in) near the Atlantic coast, and the frost-free period from under 75 days over much of the range to 180 days along the southern limits.

Flowers, cones and seed

The species is monoecious. Silvics says the male flowers are yellow and globose and the female flowers reddish, both small and appearing with the needles, in April to May in Ontario and the Lake States and mid- to late May in interior Alaska. Ripe cones are brown and 13 to 19 mm (0.50 to 0.75 in) long, ripening in August to September. Isolated trees on peatlands and in plantations begin bearing viable seed at 12 to 15 years of age, large quantities generally start at 40 years, and the handbook gives 75 years as the optimum age. Good seed crops come at 3 to 6 year intervals. A single vigorous open-grown tree may bear as many as 20,000 cones holding more than 300,000 full seeds in a good year. The seed is 3 mm (0.12 in) long with a wing 6 mm (0.25 in) long, and the handbook says few seeds fall farther than twice the tree height, though reproduction can be good as far as 60 m (200 ft) from seed trees if seedbeds are favorable.

Growth, shade and roots

The handbook says that with abundant light tamarack is one of the fastest growing conifers on uplands in the boreal and northern forest regions, and on peatlands it outgrows any other native conifer, while on water-covered stagnant peatlands a tree may be only 2 m (6 ft) tall at 55 years. In interior Alaska mature trees are often only 3 m (10 ft) tall and 8 cm (3 in) in diameter. Tamarack is very intolerant of shade, must be dominant to survive and in mixed stands must be in the overstory, and it prunes itself well. The root system is typically shallow and spreading, 30 to 61 cm (12 to 24 in) deep, and peatland trees have wide root systems and form no taproots; as the moss layer deepens, new roots develop on the stem above the original root collar.

Wood

The Wood Handbook (FPL-GTR-282, 2021) says tamarack, also known as eastern larch and locally as hackmatack, grows from Maine to Minnesota, with the bulk of the stand in the Great Lakes states. It describes yellowish brown to russet brown heartwood, whitish sapwood generally under 3 cm (1 in) wide, coarse texture, no odor or taste, and an abrupt change from earlywood to latewood, with weight and most mechanical properties intermediate. It names pulpwood, lumber, railroad crossties, mine timbers, fuel, fence posts and poles as uses. Silvics says the principal commercial use is pulp products, including the transparent paper in window envelopes, and that rot resistance is behind its use for posts, poles, mine timbers and railroad ties.

Wood Handbook figure	Green	At 12% moisture content
Specific gravity (Table 5-3b)	0.49	0.53
Modulus of rupture, lbf per square inch (Table 5-3b)	7,200	11,600
Side hardness, lbf (Table 5-3b)	380	590

The green weight is in the NRS-38 table, the same figure used in the log weight calculator.

Damaging agents the handbook names

Fire and flooding. Silvics says the thin bark makes tamarack highly susceptible to fire damage, and that its shallow roots mean all but very light burns usually kill it on peatlands. Abnormally high water levels often kill stands; the handbook names wetland road crossings and beaver dams as the primary causes of flooding and says road-caused flooding has killed or slowed tamarack on thousands of hectares in northern Minnesota. Strong winds can uproot large trees on wet sites, though it calls tamarack fairly windfirm compared with black spruce.
Larch sawfly. The handbook calls it the most destructive insect enemy of tamarack, with periodic epidemics across Canada and the northern United States. It says growth declines markedly after 4 to 6 years of outbreak and trees die after 6 to 9 years of moderate to heavy defoliation.
Larch casebearer and others. The larch casebearer, a European native the 1990 handbook records as widely distributed in eastern North America, is called a serious defoliator that has caused extensive mortality in some areas. The spruce budworm can severely damage tamarack growing with balsam fir and white spruce during an outbreak; see the spruce budworm page. Other insects named are the larch bud moth, spruce spider mite, larch shoot moth, eastern larch beetle (which feeds mainly on weakened, dying or dead trees) and Warren's collar weevil.
Diseases. Silvics says tamarack hosts many pathogens, but none is serious enough to have an economic impact on its culture, and calls it essentially free of stem diseases. It lists leaf rusts, Armillaria root rot, butt rots, a false velvet top fungus that has killed pole-sized trees, and the heart rots brown trunk rot and red ring rot.
Mammals. Snowshoe hares kill many seedlings in parts of the Lake States, Alberta and Alaska, and porcupines commonly feed on the inner bark and deform the stem or kill the tree, especially in plantations.

For who takes reports of regulated pests, see reporting a pest in the United States, and pests and diseases by country sets out which ones agencies regulate.