Paper birch (Betula papyrifera)

Description

Betula papyrifera (paper birch, also known as white birch and canoe birch) is a short-lived species of birch native to northern North America. Paper birch is named due to the thin white bark which often peels in paper like layers from the trunk. Paper birch is often one of the first species to colonize a burned area within the northern latitudes and an important species for moose browse. The wood is often used for pulpwood and firewood. It is a medium-sized deciduous tree typically reaching 20 metres (66 ft) tall, and exceptionally to 130 feet (40 m) with a trunk up to 30 inches (76 cm) in diameter. Within forests it often grows with a single trunk but when grown as a landscape tree it may develop multiple trunks or branch close to the ground. Paper birch is a typically short lived species. It handles heat and humidity poorly and may only live 30 years in zones six and up, while trees in colder-climate regions can grow over 100 years. B. papyrifera will grow on many soil types, from steep rocky outcrops to flat muskegs of the boreal forest. Best growth occurs on deeper, well drained to dry soils depending on the location. In older trees the bark is white, commonly brightly so, flaking in fine horizontal strips to reveal a pinkish or salmon colored inner bark. It is often with small black marks and scars. In individuals younger than five years, the bark appears a brown red color with white lenticels, making the tree much harder to distinguish from other birches. The bark is highly weather-resistant. It has a high oil content and this gives it its waterproof and weather resistant characteristics. Often, the wood of a downed paper birch will rot away leaving the hollow bark intact. The leaves are dark green and smooth on the upper surface, the lower surface is often pubescent on the veins. They are alternately arranged on the stem, oval to triangular in shape, 5–10 cm (2–4 in) long and about ​2⁄3 as wide. The leaf is rounded at the base and tapering to an acutely pointed tip. The leaves have a doubly serrate margin with relatively sharp teeth. Each leaf has a petiole about 2.5 cm (1 in) long which connects it to the stems. Betula papyrifera has a moderately heavy, white wood. It makes excellent high-yielding firewood if seasoned properly. The dried wood has a density of 37.4 lb/cu ft (0.599 g/cm3) and an energy density 20,300,000 btu/cord. While paper birch does not have a very high overall economic value, it is used in furniture, flooring, popsicle sticks pulpwood (for paper), plywood, and oriented strand board. The wood can also be made into spears, bows, arrows, snowshoes, sleds and other items. When used as pulp for paper, the stems and other non trunk wood are lower in quantity and quality of fibers and consequently the fibers have less mechanical strength, nonetheless, this wood is still suitable for use in paper. The sap is boiled down to produce birch syrup. The raw sap contains 0.9% carbohydrates (glucose, fructose, sucrose) as compared to 2-3% within sugar maple sap. The sap flows later in the season than maples. Currently, only a few small scale operations in Alaska and Yukon produce birch syrup from this species.