Alaska Science Camps, Fairs & Experiments

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Selecting a
Birch Tree

For centuries, Alaska Natives have made all of their tools from local resources. Only a few materials were traded with the Russians.

Alaska has several different kinds of trees, but there is only one hardwood that is suitable for making dogsleds, snowshoes, and other durable items. The Alaska birch tree stands alone being the toughest hardwood in the state.

There are several considerations in picking a birch tree for use. The tree must be straight splitting, have few or no knots, have a minimum of heartwood, and have tough fibers. There are few trees available that have all these qualities. As oldtimers traveled, they constantly watched for "the tree" from which they would make their next snowshoes or sled.

It often takes longer to find the perfect tree than it does to make the snowshoes or sled.

On the average, trees from the Lower 48, like oak, hickory, and ash are stronger than Alaska birch. However, experience shows that a well-chosen birch tree is tougher than commercial hickory and ash. This is particularly true since lumber comes to us sawn from trees with little regard for the grain of the wood. If the grain is straight and intact, the wood of any tree is stronger than if it is sawn.

Alaska birch does tend to rot easily, and must be stored carefully. 

Straight grain

There are several ways to determine the grain before falling a tree and attempting to split it.

1. Look at the grooves or ridges on the tree. Do they go straight up, or do they twist to the side? Look under the knots. Often there are grooves leading up to the knot. Are they straight or twisted?
2. Another way to check the grain is to remove some of the bark and look at the grain. Chop a little of the wood, and peel the fibers from the tree. Do they split straight down, or do they twist a little to the side?

If the grain is twisted, it is better to find another one. Snowshoes and sleds are difficult to make. It is worth the time and effort to find the right tree.

Knots

It is very difficult to find a tree with no knots. They disrupt the grain of the wood and weaken it, particularly on thin pieces like snowshoe frames. There is a difference between knots, however. Obviously some are larger than others. There are live knots and dead knots. A live knot is the knot of a branch that was alive when the tree was harvested. A dead knot is from a branch that was dead. Live knots are much stronger.

Heartwood

Inside many birch trees is dark heartwood. This wood is contrasted with the white wood on the outside. Heartwood isn't necessarily weaker than the outside wood, but the water content is far less. If a sled member has a little heartwood and the rest is white wood, it will tend to warp strongly towards the white wood when it dries, shrinkingmore on that side than the heartwood side.

Tough fibers 

Trees are like people. Some are tough and some aren't. If a tree has tough fibers, the snowshoes and sleds will last a long time. Strong pieces can be made smaller and therefore lighter. One tree might be three to four times stronger than another.

There are several things that make a tree tough. 

Genetics

If a tree comes from the seeds of tough trees, it too will be tough.

Soil

A tree on good soil with proper minerals and water content can also be a tough tree.

Location

If a tree is in a sheltered place, the fibers of the tree will tend to be weaker. If the tree grows in a windy place, the tree will tend to be more gnarled, but the fibers will be very strong, as the wind bends and flexes the tree, toughening the fibers. I once built a dogsled from small trees that had grown on a hilltop, and it was the strongest sled I ever owned. The wind had conditioned the wood to flex without breaking.

Picking a Tree

To choose a good birch tree, it is important to be looking all year long. A hunter might be chasing a moose and pass a good tree in a location he has never been before. He makes a mental note where the tree is.

The first qualities to look for are:

• Is the tree physically straight for the length of the piece you want to make? Are there too many knots?
• Next, look at the topmost branches. Are they straight up or drooping? If the branches are drooping, the fibers tend to be more flexible. If they are straight up, the tree tends to be more brittle.
• Look for ridges on the sides of the tree or under the knots. Are they straight up the tree or do they indicate the grain of the tree is twisted?
• Look for the black flecks that indicate excessive heartwood.
• Chop a little of the bark away from the tree. Chop a few fibers and pull them away from the tree. Do they split off quickly indicating that the wood will be easy to break? Do they split in a way that indicates the grain is twisted, or is it straight up and down the tree? Bend the fibers that peel off. Are they tough or do they break easily? If it is winter and the wood is frozen, put the wood fibers in your mouth to thaw before bending and testing them.

Splitting

You will have to ask Elders in your community to learn how to split. Even a good, straight-grained tree will split crooked without the proper methods. Splitting is an art.

Test the above statements by observing the qualities of different trees. Test the fibers of five to ten trees.

Compare the fibers of a tree that has droopy branches to ones that have straight branches. Which flex better without breaking?

Compare the fibers of trees grown in protected groves with those grown in windy places. Which seem tougher?

Compare the amount of heartwood in trees that have many black flecks on the bark with those that don't. Which have the most heartwood? (Does someone in your village have birch in the woodpile where you can easily observe this?)

Chop a sliver of bark from several birch trees. Test the exposed wood fibers. Can you detect a difference in their strengths?

Can you tell if the grain is straight or twisted? Look for the outward signs of twisted grain or straight grain. Compare those signs with the actual grain. Do the outward signs give a clear indication of the true grain of the tree?

Split a thin piece of birch from a block. Saw another piece identical in size to the split one. Try bending them. Which bends best?

Test a good birch tree with some strips of oak, ash, and hickory. What conclusions can you make about quality, grain, weight, strength, and durability?

What conclusions can you draw about selecting a good birch tree?

	© 2004 Alaska Native Knowledge Network. All rights reserved. A partner with the Alaska Rural Systemic Initiative This material is based upon work supported by the National Science Foundation under Grant No. 0086194. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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