Yellow birch

Appearance

It is a medium-sized, typically single stemmed, deciduous tree reaching 60–80 feet tall ) with a trunk typically 2–3 ft in diameter, making it the largest North American species of birch. Yellow birch is long-lived, typically 150 years and some old growth forest specimens may last for 300 years.

It mostly reproduces by seed. Mature trees typically start producing seeds at about 40 years but may start as young as 20. The optimum age for seed production is about 70 years. Good seed crops are not produced every year, and tend to be produced in intervals of 1–4 years with the years between good years having little seed production. The seeds germinate best on mossy logs, decaying wood or cracks in boulders since they cannot penetrate the leaf litter layer. This can lead to odd situations such as yellow birches with their roots growing around a tree stump, which when it eventually rots away leaves the birch standing atop stilt-like roots. Yellow birch saplings will not establish in full shade so they typically need disturbances in a forest in order to establish and grow. The tree is fairly deep-rooted and sends out several long lateral roots.

⤷ The bark on mature trees is a shiny yellow-bronze which flakes and peels in fine horizontal strips. The bark often has small black marks and dark horizontal lenticels. After the tree reaches a diameter greater than 1 ft the bark typically stops shredding and reveal a platy outer bark although the thinner branches will still have the shreddy bark. There is an uncommon, alternate form of the tree which grows in the southern part of the range. F. ''fallax'' has darker gray-brown bark which shreds less than the typical form.
⤷ The twigs, when scraped, have a slight scent of wintergreen oil, though not as strongly so as the related sweet birch , which is the only other birch in North America to also smell of wintergreen. However, the potency of the odor is not considered a reliable identification method unless it is combined with other characteristics.
⤷ The leaves are alternately placed on the stem, oval in shape with a pointed tip and often a slightly heart shaped base. They are 2–5 in long and typically half as wide with a finely serrated margin. They are dark green in color on the upper side and lighter on the bottom, the veins on the bottom are also pubescent. The leaves arise in pairs or singularly from small spur shoots. In the fall the leaves turn a bright yellow color.
⤷ The leaf has a very short petiole 1⁄4–1⁄2 in long.
⤷ The flowers are wind-pollinated catkins which open in later spring. Both male and female flowers will occur on the same tree making the plant monoecious. The male catkins are 2–4 in long, yellow purple, pendulous , and occur in groups of 3-6 on the previous year's growth. The female catkins are erect and 1.5–3 cm long and oval in shape, they arise from short spur branches with the leaves. The fruit, mature in fall, is composed of numerous tiny winged seeds packed between the catkin bracts.
⤷ The seed is a winged samara with two wings which are shorter than the width of the seed which matures and gets released in autumn.

Status

It is listed as endangered in Illinois.

Habitat

The twigs are browsed on by whitetail deer, moose and cottontails Deer eat many saplings and may limit regeneration of the species if the deer population is too great. Ruffed grouse and various songbirds feed on the seeds and buds. Due to the thin bark of the tree yellow bellied sapsuckers feed on this tree by drilling holes in the tree and collecting the sap. Broad-winged hawks show a preference for nesting in yellow birch in New York.

Several species of Lepidoptera including the mourning cloak and dreamy duskywing feed on ''B. alleghaniensis'' as caterpillars.

Yellow birch is often associated with eastern hemlock throughout its range due to their similar preferences in habitat. It mostly grows from 0–500 m in elevation but may grow up to 1000 m. It reaches its maximum importance in the transition zone between low elevation deciduous forests and high elevation spruce and fir forests. Due to the thin bark and lack of ability to resprout, it is easily killed by wildfire.

Sugar maple exerts allelopathic effects on seedlings of yellow birch and decreases their growth ability. The inhibitory chemical is exuded from the roots of the sugar maple and has a very short soil half-life, it no longer has effects on birch after 5 days.

Uses

Yellow birch is considered the most important species of birch for lumber and is the most important hardwood lumber tree in eastern Canada; as such, the wood of ''Betula alleghaniensis'' is extensively used for flooring, furniture, doors, veneer, cabinetry, gun stocks and toothpicks. It was once popular for wagon wheels. Most wood sold as birch in North America is from this tree. Its wood is relatively strong, close grained, and heavy. The wood varies in color from reddish brown to creamy white and accepts stain and can be worked to a high polish. Like most birches, yellow birch wood rots quickly due to its tendency to trap moisture. The cellulose from rotting birch logs was collected by Native Americans and used as a quick fire starter.

In the past, yellow birch has been used for distilling wood alcohol, acetate of lime and for tar and oils. Oil of wintergreen can be distilled from the bark.

The papery, shredded bark, is very flammable due to its oil content and can be peeled off and used as a fire starter even in wet conditions.

Yellow birch can be tapped for syrup similarly to sugar maple, and although the sap has less sugar content, it flows in greater quantity than sugar maple. When the sap is boiled down, the wintergreen evaporates and leaves a syrup not unlike maple syrup. The sap can also be used as is in birch syrup or may be flavored. Tea can also be made from the twigs and inner bark.

Cultural

''Betula alleghaniensis'' is the provincial tree of Quebec, where it is commonly called ''merisier'', a name which in France is used for the wild cherry.