Maine’s Paper Birch
Paper birch (Betula papyrifera) is a tree species native to Northern North America from the Maritime Provinces to Western Alaska. Abundant in Maine, paper birch has adapted to grow in a wide variety of soil types and topographies, although it is found mostly in areas with well-drained sandy loam soils.
Paper birch trees are identified by their paper-like bark and oval-shaped leaves with double-toothed edges.
The bark from paper birch trees is naturally waterproof, insect resistant, and has no odor, and can be cut, shaped, and folded in various sizes. Birchbark traditions were central to the material culture of the native people of Maine. Everything from canoes, containers and coverings for housing to moose calls and novelty goods could be made from the paper-
like bark.
Today birchbark canoes and containers are made by artists drawing on traditional motifs as well as innovative new forms and designs.
What makes birchbark waterproof and a great material for canoes?
Betulin is a naturally occurring triterpene which makes up roughly 30% of the dry- weight extract from birchbark. Betulin is hydrophobic (lacking affinity for water), giving birchbark its stellar waterproofing ability. In addition to providing bark for canoes, house coverings, and containers, paper birch trees also play important roles in the ecosystems where they grow.
Paper birch trees are abundant in Maine and provide an important source of nutrients for moose and other animals during winter months when other food sources are scarce. Paper birch is a favorite feeding tree of yellow-bellied sapsuckers, a medium-size woodpecker that breeds in northeastern North America.
The seeds and buds from paper birch trees provide food for grouse and twigs are browsed by deer, moose, and snowshoe hare.
Paper birch are fast-growing and relatively short-lived trees, rarely living past 140 years. They generally bear seeds between 40-70 years of age, although they can begin producing seeds after just 15 years. The winged seeds are dispersed by wind, sometimes traveling over 150 feet. However, most seeds do not travel outside of the stand.
In Maine and throughout North America paper birch trees face a number of ecological and human-caused threats including deforestation, insect pests, disease, and climate change.
Increased demand for paper and a shortage of rags caused paper mills to begin using wood as their fiber source. In the decades following the late 19th century, Maine led the nation in producing paper.
Paper birch is one of the trees used to produce pulp for paper mills. Unsustainable harvesting practices in Maine have changed forest composition and stand sizes. As a result, it is increasingly difficult for Wabanaki artists to find quality paper birch stands for
canoe making.
Common insect pests of paper birch include leaf miners, forest tent caterpillars, and birch casebearers. These insects and others feed on the leaves, causing them to turn brown and become distorted. The stress from defoliation can increase susceptibility to infestation from bronze birch borers. Although rare in the northern areas of the paper birch’s range, bronze birch borer infestations are quite damaging and
oftentimes fatal.
Several diseases also affect paper birch trees. Fungi can cause canker disease, killing sapwood and damaging areas on the drunk and large branches. Dieback, which is characterized by dead branches in the tree crown, mostly affects trees experiencing environmental stress such as drought.
Paper birch trees are sensitive to temperature increases and drought. Climate change models assuming high emissions trajectories have shown diminishing paper birch habitat in North America. The increased stress from environmental change could lower the ability of trees to fight insect pests and disease. This could pose challenges for both ecosystems and people.
Additional Resources:
Paper birch trees are common in early successional forests. Learn more about these forest communities in Maine by following this link.
Follow this link to a video featuring David Moses Bridges, a basketmaker who uses birchbark to make baskets and canoes.
Learn more about paper birch identification here.