Trees: What Age is a Good Age?

You probably learned how to tell a tree’s age back in sixth grade (maybe even earlier). Every year a tree is alive, a new ring develops in its trunk. But these rings reveal more than just how many years old a tree is. Tree rings hold information about climate conditions specific to each year. Dendrochronologists (people who study tree rings) can look at the rings in wood that was harvested thousands of years ago and determine exactly when it was alive.

Speaking of tree age, what age do you think is the ideal age for a tree to be?

Young?

Middle-aged?

Old?

The answer is: All of the above. A diverse forest with different ages and a variety of plant species makes for a healthy ecosystem.

There are benefits to all ages of trees.

Young trees are great for our air. Like humans, trees grow the most when they are young. In order to grow, trees have to photosynthesize. During photosynthesis, trees absorb carbon, sunlight, and water and they produce sugar to eat and oxygen, which we use to breath. So, by understanding basic photosynthesis, you can see that young trees are best at absorbing carbon and producing oxygen, thus ensuring healthy air quality for our planet.

Young trees are also better than old trees at fighting off disease and pests. For example, the pine beetle typically only kills pine trees that are more than 80 years old. This is because the younger trees are better at producing sap that blocks the beetles from getting inside the tree. (It looks kind of gross, I know.) So if we have too many old trees, disease and pests can spread out of control and cause immense damage to our forests.

Another benefit of the younger trees is they are less likely to be struck by lightning (which can cause forest fires). Forest fires have their benefits—they help renew aging forests—but we don’t want our forests to be too prone to burning. When fires get out of control they can devastate habitat and risk spreading to towns and people. Since lightning causes 90% of burned forest area in Canada, young forests help prevent these massive forest fires.

Finally, there are certain animals that prefer younger forests. Deer, moose, and elk thrive in areas that have recently experienced events that produce new vegetative growth such as fires, timber harvests, and storms. For more information on forest ecology, click here.

Now, before you start thinking young trees are the only good kind of tree, I will tell you why old trees are also very important.

First of all, they are beautiful! There is something very majestic about old trees. And the density and sponginess of an old forest is kind of mysterious and ignites a desire for exploration (Is it just me?). I remember the fun I had as a kid, wandering through the old forest behind my family’s acreage. I also love going to the mountains and finding a forest to hike through. And quading wouldn’t be the same without big trees to weave around.

Older trees are also usually better for harvesting. In Alberta, our trees grow very slowly, so it takes about 80 – 120 years of growth before a tree is large enough to use for products like lumber and pulp. Due to the slow growth of Alberta’s trees, the fibres are very long and strong, producing very high quality paper and wood products.

Just like some animals prefer young trees, other animals prefer old trees. For example, wolverines and caribou prefer older forests because the larger trees provide protection from predators. Old trees also serve better dinner for some animals. Caribou like to munch on the mosses and lichens that grow in old forests.

Finally, old forests are good for preventing the spread of ground fires. These fires spread easily in the presence of dense ground foliage (common to young trees). The foliage on old trees is up high, far from the ground, so ground fires don’t spread as quickly.

As you can see, it is important that we have diverse forests so that different species of plants and animals can thrive. Also, forest diversity provides us with healthy air and ensures we can always use the valuable resources in the forests. It’s a good thing we have foresters and forest technicians who understand the need for diversity in forests and who ensure that we have a range of tree species and ages growing in our forests. Foresters and forest technicians manage forest diversity by matching the appropriate tree species to site conditions and monitoring forest health. That’s why we call them the stewards of Alberta’s forests. If you’re interested in becoming one of these forest stewards, click here for more information.

Maybe the forest dragon would still be around if someone had ensured bamboo forest diversity. (Kidding. I have no idea what happened to the forest dragon.)