Tree Species Identification in Our Dormant Winter Forests

Trees! Who doesn’t love them? Here in Ontario, much of our land is covered in trees year-round. In fact, 66% of the province’s land mass is forest [1]. Pretty amazing to think about, especially for those of us who live in urban and suburban communities! Trees are perennial species. This means that, once planted, they will stay alive for many years, to include the summer and winter seasons. In Ontario’s cold winters, trees slow down or even entirely halt photosynthesis (the production of food), with some going so far as to completely shed their food factories (their leaves) [2]. This strategy allows trees to save their energy for spring, when they can grow their leaves back relatively. Trees that lose their leaves in the winter are called “deciduous trees”. Other trees, called “coniferous trees”, have leaves that take a lot of resources to grow back if lost.

Coniferous trees have evolved to hold onto their leaves, as it makes more sense to hold onto them through the winter than to spend most of the spring and summer growing them back.

When walking through Ontario’s beautiful forests in the winter, take some photos of the trees that you see. It can be very difficult to tell them apart, but there are a few key clues to look for.

Bark

Tree bark does not change appearance throughout the year. Bark texture and colour can be great ways to identify trees in the wintertime. Birches and beeches have a distinctly smooth bark, whereas oaks and sugar maples have jagged and fractured surfaces. Birch trees are characterized by their off-white bark with black spots, and red oaks have a slightly— you guessed it— red hue.

A birch tree such as a paper birch (Betula papyrifera) has a very distinctive bark. © eknuth, some rights reserved (CC-BY-NC)

Physiology

Just like humans, no two trees are alike. They have evolved to grow and develop in different shapes and sizes. Despite the individual differences from specimen to specimen, each tree species has some physical characteristics. Oak trees will have thicker and fewer branches, maple trees will have thinner and denser branches, and birch trees will be skinny, with branches well above the height of your head.

Fruit

All deciduous trees are part of a larger group of plants called “angiosperms”—the most diverse group of plants on Earth. One of the defining traits of all angiosperms is that they all produce fruits. Not all deciduous trees will produce prominent fruit in the winter, but keep an eye out. You might see bright red berries of the winterberry (don’t eat them, they’re quite toxic). These are small and soft. Larger berries could belong to the hawthorne trees, but those are a bit harder to find in Ontario.

Winterberries are easily identifiable by their fish egg-like appearance. © Zach Baranowski, some rights reserved (CC-BY-NC-ND)

Expert Referral

If you’re uncertain about a tree, snap a photo and post it to Ecosparks’ iNaturalist page. Even if all you can confirm is whether it is deciduous or not, it won’t take long for iNaturalist’s tree experts to make the identification for you.

Post by Philip Harker, an undergraduate ecology student at the University of Toronto.

[1] https://www.ontario.ca/page/state-ontarios-natural-resources-forest-2021, [2] https://carnegiemnh.org/how-do-trees-survive-the-winter