The Magic of Maples

Vancouver is the land of the giant evergreen tree. Our Douglas-firs, Hemlocks, and Cedars. They dominate our forest, towering over and casting such a deep shade that few plants can grow below. There is really only one deciduous tree species that can compete. This is our national tree, a Canadian icon, the Maple Tree.

There is an important distinction to make between coniferous, needle-leaf trees (Gymnosperms, which means ‘naked seeds’, think trees with cones!) and broadleaf trees (Angiosperms, ‘covered seeds’, think apples, cherries, or nuts). We often think of both of these groups under the same classification of “trees”. When really, Gymnosperms vs Angiosperms is like Insects vs Mammals. While they both have wood and leaves, the structure of the wood and leaves is actually radically different between the two groups. It can be misleading to talk of both as trees because they are so fundamentally different.

Gymnosperms are almost twice the age of Angiosperms in evolutionary time. Gymnosperms are ancient dinosaur trees, while Angiosperms really only came into their own with the rise of the mammals and extinction of dinosaurs. Douglas-firs are ancient elders and Maples are punk kids encroaching on their territory. Gymnosperms were used to a world of less CO2 and less water, so learned to grow as efficient as possible. With a wood structure that uses as little water as possible and needle-leaves that are durable and last for multiple years. Angiosperms are short-lived, flamboyant showboats in comparison. They often lose and regrow their leaves every fall, requiring a large amount of water and CO2 for this incredible production. They also spent a lot of energy on beautiful flowers and tasty carbohydrates (fruit!) to attract animals and insects for pollen and seed spreading.

When you walk in the woods though, the easiest difference to see between the two is how angiosperms are sun-chasers, putting branches out in every direction, grabbing as much sun energy as possible. Gymnosperms trunks grow straight and true with small branches, their more efficient wood structure meaning they need less sun.

Often on my tree walks I focus on the identifying the three main gymnosperm trees of Pacific Spirit Park (Douglas-fir, Cedar, Hemlock). People learn to identify these trees by their bark and it quickly becomes easy to tell which is which. So then I try and make it a bit harder and point to a new tree and watch as they struggle to guess what it is. It’s bark looks a bit like Douglas-fir, no wait more like a Hemlock. Hmmm. They get stuck, doubting themselves. Then I encourage them to look up. And quickly they see how this tree has huge branches growing out to side near the top of the trunk, it is not a straight and true gymosperm. It is the only tree that can compete with the dense shade of the gymosperms. It is a Maple. One of of biggest native maple species. The Bigleaf maple.

Maples! What incredible trees. They do a few things really well. They have wide leaves, where other broadleaf trees mainly have leaves longer then they are wide, maples the opposite. Wide leaves gives them the ability to grow better in the shade, spreading to catch more sun.

Maples also have more long pointed edges, ‘drip tips’ then other trees do. Using the all-important and almost paradoxical feature of water know as cohesion (where water molecules will stick together, and stick together better on smaller surfaces), these tips allow Maples to hold water on ther leaves during rain and release it slowly. As any hardcore Vancouverite walker can attest, Maples are a great tree to take cover under during a rainstorm, but a terrible one to be under just after the rain has finished.

Maples leaves also have an incredible ability to change their size and thickness based on their location on the tree to fully exploit the level they get. It gives them great shade tolerance. Next time you are walking past a Maple, look at how the leaf stems (the petiole) of leaves vary. Stems can be super long, or very short, depending how much they need to reach to view the sun.

I could keep going with the fascinating properties of maples! But just one more; their wood. Maples produce some of the strongest wood in North American. (There are always exceptions in botany though. The Silver Maple, grows quick and massive, but it’s wood is weak it dies young and falls over, was a popular street tree until these was realized. Their are now a number of massive silver maple stumps in Vancouver neighbourhoods). Our world-famous Sugar Maple, on our flag and known for Maple syrup, was also know as Rock Maple for the strength of its wood.

Our biggest native BC Maple, the BigLeaf Maple, the one that can compete with the evergreens, was known by Indigenous tribes as the “Paddle Tree”. Paddles were an all important tool for coastal tribes. Getting paddle wood from Douglas-fir or cedar was a weaker paddle, one that would soon bend and warp under the tension of human and water resistance. Bigleaf Maple wood, would not bend, it was renowned for its strength. It still is! Bigleaf Maple Trees still get poached – harvested illegally – in the West Coast because it’s strong wood is unique in our forests.

Bigleaf Maple is fitting named so because of it’s massive leaves. One of the, if not the, biggest leaves in Canada. I’ve seen leaf stems as long as arms on them. These giant leaves let them reach over the conifers to steal the sun. The deep lobes in the leaves allowing them to bend away from the sun and wind when it gets to extreme that high up in the canopy. The strong wood of the Bigleaf allowing them to put out massive branches that also out-shade smaller conifers.

These massive Bigleaf branches are often covered with moss and ferns, creating it’s only environment, a forest in the air. It’s become a big new area of scientific exploration, these canopy forests, a whole world existing unknown above our heads. You won’t see as much moss or ferns on conifers, their straight trunks means water runs off to quickly and they don’t get enough sun. The deep curves, the sideways-growing of maple branches shows the strength of their wood and creates homes for these canopy species.

In last couple decades it was also discovered that Big Leaf Maple produces aerial roots. Small roots that grow out of the trunk and into the moss and fern ecosystem, allowing maples to capture some of water and nutrients that are held there. It’s a symbiosis, they exist together and support each other.

Bigleaf maple isn’t the only native maple you will find in Pacific Spirit Park forest. Far below the canopy of bigleaf you’ll find the underappreciated Vine Maple. Vine Maple are a small tree that has evolved to become an expert in living in shade. It does what i like to call ‘aerial acrobatics’ where it will grow sideways and trunks doing 180 turns, all to get whatever piece of sun it can. Often other bigger trees will fall on the Vine Maple and its trunks will be forced down the ground, where it will grow out some roots, reestablish itself, and then keep growing sideways.

As you can probably guess from this. Vine Maples have extremely strong wood. Stronger even then the Bigleaf. So much so Vine Maple was known for being used by indigenous tribes for tools we now use metal for, like nails. Vine Maple wood is so strong, that it is too strong to be used in wood construction, well, that combined with the fact the trees are so small and so you don’t get long planks of wood like you do with bigleaf.

This ability to put out roots from the trunk, known as layering, make Vine Maples become maze like in how they grow through the forest. Often you think you are looking at separate trees and then you realize their is a branch between them (Branch? Trunk? No real difference for Vine Maples) and they are the same tree.

The most fascinating part of the Vine Maples, their distinguishing feature, is that their bark is green. Their bark can photosynthesize just like their leafs can. This what really makes them forest floor experts. It’s why they can grow sideways and still survive. They use every ounce of sun they can find.

I hope I’ve convinced you now what incredible species Maples are! I encourage you to walk through PSP and follow the twists and bends of Vine Maple. To look up into the canopy and try catch a BigLeaf Maple and look at the moss forest growing on it.

There’s more to know with Maples. Lately PSP has seen an invasion of European maples which have been widely planted as street trees. These maples, the Norway and Sycamore Maple, are adaptable, hardy species that are starting to replace Bigleaf and Vine in the more open areas of the forest. Norway and Sycamore are generalist species that are better adapted to high temperatures cause by climate change. Plus they have an incredible seed source of well water street trees.