(resin birch)Select an option below for more information on this species
Betula neoalaskana (resin birch) is the most abundant deciduous tree in Alaska, occurring across forested regions of Denali (especially after fires) and rarely in subalpine sites. Mature trees are instantly recognizable for their straight, pale trunks with papery, peeling bark. Individuals grow up to 25 m tall, typically forming slender crowns in forests, or more branched and rounded if grown in open conditions.
When young, trees are brown-pink barked, maturing to silver-white or cream-pink. The paper-textured bark is smooth, marked with faint horizontal lines (lenticels); peeling off in long, curling strips, and interrupted on the trunk by many dark branch scars. Resin birch twigs are red-brown and covered with small white spots, resin glands.
The leaf shape is deltoid-ovate, the base round to wedge-shaped, with doubly serrate teeth and a long, narrow tip. The back of the leaf is dotted with glands, and the lower veins are typically hairy.
Betula neoalaskana produces small pendant catkins very early in spring, male and female on the same twig. Male catkins are 2.5-4 cm long, with each flower consisting of a calyx and two stamens. Female catkins are short (1-2 cm long) and cylindrical (0.5-1 cm wide), with numerous tiny flowers, each having one ovary and two styles. Seeds are small, and have two papery wings to catch the wind, wings wider than the body.
Young resin birch trees can be confused with alder (Alnus). Those shrubs never have papery, peeling bark, their leaves are larger, ovate (not deltoid) and the twigs are not dotted with resin glands. Trees of the genus Populus can at first glance look like resin birch, but, among other characters, their bark is never papery and peeling.
Slabs of this hardwood's papery waterproof bark have been used extensively in construction of boats and baskets. Wood is used for fuel, as well as cabinetry, furniture, bowls and other hand-crafts. The bark of resin birch is widely used for baskets by Alaska Natives in the interior. Birch leaf tea is used to aspirin-like effect, the sap is as a tonic or wash on skin problems including sores, and the bark is brewed in tea or chewed for fighting fevers and colds (Garibaldi 1999). Birch leaves can be eaten in spring, and the sap can be tapped in early spring and extensively boiled to make syrup.
Resin birch is a North American species of the boreal zone, occurring from Alaska eastwards to Ontario. Resin birch is widely distributed in Alaska, with its range reaching into southern valleys of the Brooks Range, to southwest Alaska in Wood-Tikchik State Park and across southcentral Alaska, including Kodiak. In Denali, B. neoalaskana occurs most frequently around the lowland basins and hills, on both sides of the Alaska Range. Though one of the more common tree species in the park, its distribution is patchy, and it rarely forms pure stands perhaps because resin birch establishes best in burned areas post-fire.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Though this species has been found in the park at up to 1053 m, it is primarily a low elevation species. The bulk of trees are found beneath 400 m, but cover is disproportionately higher at 300-500 m. This species occurs on all aspects, but is slightly more abundant on south-facing slopes. Resin birch is equally common across all angles of slopes, but it reaches the highest level of cover on moderate slopes (4-12 degrees), and also fairs well on steep slopes (20-28 degrees).
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
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