Minnesota Profile: Paper Birch
Paper Birch (Betula papyrifera)
This birch with shimmering white bark helps to define the north woods. The bark has splotches of pale green and blue lichens and eyelike lenticels, which help the tree breathe. In ideal conditions a birch may reach a height of 90 feet with a girth of 2 feet. In winter Y-shaped male catkins give the crown a unique architecture.
It has two types of buds. Short shoots rapidly produce spring leaves. Long shoots add height. Special cells produce paper-thin annual layers of outer bark, which peel as the tree's girth expands.
Tree of Many Uses
Indians used almost every part of this tree, which served them from cradle to grave. It provided sap for a spring tonic and bark to make canoes, containers for food, splints for broken limbs, covering for wigwams, and medicine. Scandinavians used birch-bark strips to weave shoes, backpacks, and containers. Campers know birch bark is the best natural fire starter. Birch wood may become lumber, veneer, or wood-chip products.
For centuries people have known that paper-birch bark decays slowly, appearing little changed after the wood inside has rotted. Fungicidal properties account for this longevity. Chemists have shown that bark compounds have potential uses as treatment for some viruses, industrial lubricants, and fungicides.
Role in Forest Ecosystems
Birches benefit forests, particularly when mixed with conifers. Birches share carbon with conifer seedlings, add nitrogen to soil through bacteria associated with their roots, and provide readily decomposed litter.
Perhaps because Minnesota has many wonderful hardwood species, foresters have generally regarded birch as less valuable than other hardwoods. Scandinavians manage it more intensively and try to obtain the highest value from each tree. Landowners cannot harvest birch and expect it to regenerate as quickly and easily as aspen does. Birch regeneration requires maintaining a seed source and an exposed mineral soil seedbed. We have little experience managing forests to produce birch products while maintaining the beauty of birches in the north woods.