Birch trees’ thin white bark helps with winter photosynthesis

Bright and white against blue skies, paper birch trees (Betula papyrifera) liven up the winter landscape, especially when contrasted against green conifers, which have made them darlings of seasonal home decor.

Paper birch, though, is so much more. According to the National Park Service, there is evidence of the trees being used by Neanderthals. These early humans extracted the tree’s extremely sticky pitch and used it as glue to secure spearheads to shafts, allowing them to hunt prey such as mammoths.

Also called canoe birch, paper birch is best known for covering wigwam shelters and lightweight canoes that made portaging between rivers and lakes far easier than early dugout designs.

The waterproof, malleable bark proved ideal for smaller objects, too, such as hand-crafted containers that could keep food dry. It also contains betulin, which has fungicidal properties that help the trees resist rot and have been used medicinally as, among other things, an anti-inflammatory and antioxidant.

Paper birch’s thin white exterior also lets sunlight penetrate its corky golden-brown inner layer, which contains chlorophyll. This allows the trees to photosynthesize sunlight on warm late-winter days, giving it a head start before the buds burst and new leaves emerge in the spring. Horizontal hyphen-like lines across birch bark, called lenticels, allow for the exchange of carbon dioxide and oxygen.

Birch trees prefer boreal forests and are deemed a pioneer species for how quickly they can populate a recently cleared area. If a landscape thick with birch trees looks ragged, it could be that they’re nearing the end of their 80- to 100-year-lifespan, which is relatively short for a tree. By contrast, white pine can live more than 450 years.

Deer, moose, hares, beavers and porcupines all nosh parts of paper birch for food. Birds including redpolls, pine siskins, finches, chickadees and ruffed grouse will eat seeds and spring catkins while yellow-bellied sapsuckers drill holes to feed on the sap and insects that get trapped in it.