Last week we looked at the yellow birch. This week, we'll look at another birch tree which is more well-known: the paper birch. Unlike the yellow birch, the paper birch grows well almost everywhere in Canada, and due to its white bark, it is something of an iconic tree. The white bark is obviously the reason why this species is perhaps more commonly referred to as white birch. In some areas, it is also called "canoe birch."
Let's start with a photo of a semi-mature tree, so we can get a good look at the bark. If you go back to our yellow birch post, you'll see that the colour difference is fairly obvious on your computer screen, but you may not find this to be the case in the field. Sometimes, a yellow birch will appear to be a lot more pale in colour, or a "white" birch might appear slightly creamy-coloured, which can really confuse observers. A better way to improve your identification skills is to look carefully at the composition of the bark, and the way that it flakes or peels off the trunk. Strips of paper birch bark are generally thicker than that of yellow birch bark. Even more telling is the outward appearance. While the yellow birch flakes in many small curls, paper birch usually peels off in much larger sections. In some instances, on mature trees, you might almost be able to peel off a piece that is about the size of a piece of photocopy paper. There is almost universal agreement that the paper birch is a very "pretty" tree.
Despite the very white bark on mature and semi-mature trees, the bark of juvenile paper birch trees is actually quite red! This is the case from the time that the tree is just a germinant or whip until the diameter of the truck is thicker than an inch or two. Here's a photo. Take a close look at the tiny white marks all over the red bark, which help clarify that these trees are paper birch:
Unfortunately, the paper birch is not as healthy as the yellow birch. A mature paper birch may only live about half as long as a yellow birch, as most only survive for about a hundred years. Incidentally, paper birch trees that live in colder climates tend to live longer than specimens in the southern part of their range. On a positive note, a single birch tree can release more than a MILLION tiny seeds (samara) in a season, so one mature tree can help generate a huge number of eventual successors.
Paper birch supposedly grows to be slightly smaller than yellow birch at maturity, but we've found that the two species are quite similar. We have a number of mature birch of both species on some of the properties that we manage, and many of the paper birch trees are around twenty meters (seventy feet) high, with a DBH (diameter at breast height) of about 60 cm (two feet). This is similar to the size of mature yellow birch in this region.
Here's a range map of the paper birch, courtesy of Wikipedia:
Fun fact: The paper birch is the provincial tree of Saskatchewan. It's also the state tree of New Hampshire.
Let's get back to examining the paper birch in more detail. Have you ever walked through the woods and found a rotten piece of paper birch on the ground, and discovered that while the bark is still intact, the wood inside has completely rotted away? This happens fairly often. This is because the bark of the paper birch has a very high oil content, and is very waterproof. This helps ensure that it is more resistant to rot than the wood in the core of the tree.
Paper birch trees are "monoecious." This means that an individual tree has both male and female flowers, called catkins. The catkins tend to develop in May or June. Female catkins are greenish, and are smaller than the brownish male catkins. By early fall, the seeds have matured and begin to fall. Seeds continue to fall throughout the winter. Most people wouldn't be able to describe a birch seed when asked, because they are fairly tiny and not at all obvious to someone taking a walk through the woods. However, next time that you're walking through a stand of birch trees with snow on the ground, take a close look at see if you see a lot of small brown specs on the surface of the snow. These may be birch seeds!
To see a good illustration showing how small birch seeds are, check out this short YouTube video from someone who is demonstrating how to grow silver birch:
https://www.youtube.com/watch?v=4zcyYRqe9-g
Ok, it's time for some more fun facts about paper birch!
1. If you're planting both paper birch and black walnut on the same property, don't plant them close to each other! The roots of the black walnut secrete a chemical (juglone) which is very toxic to paper birch trees.
2. Although paper birch bark is a staple food for moose, it is full of lignin which is hard to digest. For this reason, moose need to eat many other types of plants in combination with the birch. Incidentally, deer also love to eat the bark of the paper birch, especially once the snow cover gets deep and ground forage is hard to get to.
3. The leaves of the paper birch often appear in pairs. They have toothed edges which are called margins.
Birch trees are an important part of the mix of hardwoods that we plant
on the properties that we manage. We have to think about carbon
sequestration and longevity, so we tend to plant a greater number of
yellow birch than paper birch. However, paper birch are very
attractive so it would be a failure not to include them. As a
forest reaches a steady state maturity, with old trees being gradually
replaced by young trees, a mix of yellow and white birch is beneficial.
Having said that, paper birch is more of a pioneer species than yellow birch, which means that it thrives better than yellow birch in
openly disturbed forests with lots of exposure to sunlight. In the
long term, we feel that yellow birch (a shade-tolerant successional species) has a bit of an advantage over
paper birch for a mature forest with lots of shade. Here's a photo of some of our white birch seedlings:
Thanks for reading ...
- Jonathan Clark
www.replant-environmental.ca
Replant.ca Environmental is a Canadian company that plants trees for carbon capture and builds community forests. We also plant trees in national, provincial, and municipal public parks to mitigate damage from wildfires, storms, insects, and forest diseases. We operate thanks to numerous small contributions from the general public, in addition to larger project sponsorships from businesses and corporations around the world. If you'd like to learn how to show your support, visit our donations page. Even if you aren't able to make a contribution, we very much appreciate when people are able to share our posts or our website link on social media, to help spread the word about the work that we're doing!
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To learn more about the various species that we plant, visit the conifers page or the deciduous (hardwoods) page on our website. Thanks so much for your interest!
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