Trees through the world

Photo of a Florida bald cypress (Taxodium distichum)

Is there a big difference between trees from different continents? Marianne Saint-Georges de Champlain, Quebec

Your question is very vague! We would need to know if you're talking about the same tree species or different trees that grow in different climates.

If you're talking about the same tree species, but on different continents, there may be differences. If you plant a tree outside its hardiness zone, it will be harder for it to grow, and it will not be as impressive. For example, the redwoods planted in Europe barely measure 30 meters high and fall short of the magnificence of those of the American west coast. Similarly, Quebec trees planted in Europe do not have the same fall colors than they do here, as the temperature does not fall as low over there than here (see text by Michel Labrecque on fall colours).

If you're talking about the difference between tree species by continent, then yes, there are big differences. Think of the growth conditions specific to each continent: tropical, desert, temperate, boreal, ... These factors do not only distinguish trees from one continent to another but also within each continent. A tree from a boreal climate is very different from the one growing in a mangrove forest, with its roots in water. They can both be on the same continent. Biodiversity is also much higher in the tropics. It's the same for trees. In North America, the United States and Canada, there are about 620 tree species. South America and Central America, even when limited to their tropical surroundings, count tens of thousands of species of trees.

You can also think about the two hemispheres ... In the Northern Hemisphere continents, we find large boreal coniferous forests which are not present in the Southern Hemisphere. Why? Look on a globe (or on Google Maps)... The Northern Hemisphere has a lot of lands at high latitudes in Canada, Russia and Scandinavia. In the Southern Hemisphere, it's the opposite, there is very little emerged land.

We must also consider the history of the continents. Earth has been under the influence of repeated ice ages. Great continental glaciers extended periodically from the poles onto the lands. In Europe, plant species could not always "flee" south, since their retreat path was blocked by the Alps. Several tree species died off following these successive ice ages. Therefore, tree diversity in Europe is lower than on other continents.

Finally, continental drift isolated, on various islands, trees that developed there unlike anywhere else. Australia (which is a rather large island) is almost the only place where there are naturally growing eucalyptus. Madagascar has six of the eight species of baobabs on Earth. And if you visit New Caledonia, an archipelago in Oceania, you can admire thirteen of the nineteen araucaria species on Earth.

Mathieu Lanteigne-Cauvier
Scientific writer
Trees Inside Out

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