Have you ever wondered why some trees lose their leaves in the fall while others don’t?
Well, there are two main types of trees in nature: Coniferous and Deciduous. Coniferous trees, like White pine and spruce trees, usually have needle-like leaves.On the other hand, Deciduous trees, such as maple, oak, and birch trees, have regular leaves. These are the ones that drop their leaves in the fall.
But why do some trees choose to let go of their leaves?
It turns out there are some good reasons for this. Leaves are where trees make their food using sunlight, carbon dioxide from the air, and something called chlorophyll. Through this process, trees make oxygen and water vapor, which they release into the air. This process is called photosynthesis.
In the winter trees stop this process by losing their leaves which helps them conserve energy, and keeps more water vapor inside the tree. Another advantage is the change in shape of the tree without leaves.
In the winter, trees stop making food and lose their leaves. This helps them save energy and keep more water inside. Another advantage is that without leaves, the shape of the tree changes.
Trees with leaves can catch the wind like a sailboat sail, which can be risky during winter storms with heavy snow and ice. Coniferous trees have a waxy covering on their needles that helps keep moisture inside. They also have tall, thin shapes that can handle strong winds and heavy rain or snow.When snow piles up on their branches, these trees bend down and rest on their lower branches. This extra support prevents the branches from breaking.
But how do trees know when it’s time to drop their leaves?
Believe it or not, trees can sense changes in the length of days and nights. That’s why they lose their leaves even if the weather is still warm in the fall. In spring, they know it’s time to grow leaves again when the nights become shorter.
Now, let’s talk about why leaves change colors.
Chlorophyll is the chemical that exists in the green parts of plants and does photosynthesis. It is in fact the thing producing the green colour. Trees intentionally fill their leaves with chlorophyll to generate as much energy as possible during the summer months. They store extra energy in the form of sugar in the roots and inside their bark.
As fall approaches, trees sense cooler temperatures and less sunlight each day. They stop making chlorophyll, and the green colour fades away.Then, other colors hidden in the leaves start to show. Some leaves turn yellow and orange because of pigments called carotenoids. In some trees, red and purple pigments called anthocyanins take over. Some trees even have both types of pigments, with colors changing as the season goes on.
Does it hurt trees to lose their leaves?
No, it doesn’t! Trees are pretty clever. As fall comes, they close off the vessels that carry water and nutrients to the leaves. A special layer of cells grows between the leaf stem and the tree branch. These cells gently separate the leaf from the rest of the tree, without leaving a wound. That’s why it’s tough to pull leaves off trees in spring and summer – the tree is holding onto them tight. During winter, the tree goes into a resting phase to save energy for when it wakes up and starts growing again in spring.
Tricky Trees!
Introducing the incredible tamarack tree! Also called the eastern larch tree, this special conifer calls our area home. It’s a bit of a rule-breaker in the tree world, and here’s why.
Unlike most conifers we’ve talked about, the tamarack is a deciduous conifer. That’s a fancy way of saying it has needle-like leaves, but it lets them go before winter comes. It’s like nature’s way of getting ready for the cold.
In the fall, the tamarack puts on a show you won’t want to miss. Its needles, usually green, transform into a stunning shade of gold before gently drifting down to the ground. If you’re out and about during autumn, keep your eyes open for these golden beauties!
Challenge Time!
See if you can visit a tamarack tree this summer and return in the fall and winter to see how it changes! Bonus points if you can capture a picture each season!
Learn more about how to identify tamarack trees at https://www.ontario.ca/page/tamarack.