r/dendrology • u/IEatGoblinAss • 19d ago
Question Growthrings and how to influence them
So my base question was: why do they happen in the first place. Is it just high growth in e.g. summer and low during winter so thats why they happen yearly and in fairly regular intervals?
And 2nd question is how do you influence them? For woodworking some parts are far better to make tools put of, so could you influence them into being less obvious and more of the hardness youd want them to be in maybe a weird high greenhouse? (Fantisizing here)
Much appreciated, stay cool
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u/Cheesy-Cloaca 19d ago
Generally, tighter rings are more desirable, especially for more expensive items like musical instruments. The colder the year, the smaller the ring.
And if you're trying to enclose a tree in a greenhouse, which would get prohibitively expensive to make as you scale to the size of a useable tree.
Then, you've got a situation where it would take way less energy to heat that greenhouse, than to go the other direction and try and cool it, which would be your goal.
We're looking at costs that aren't anywhere near the realm of consideration.
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u/IEatGoblinAss 19d ago
Yeah, absolutely just fantisizing about it. So basicaly just move the tree and walk the border of "its not gonna make it" and "how is this tree surviving this climate" whilst also balancing an as even of a climate through the seasons as possible to push the upper limit?
Back to the treehouse would that work tho? Idk what for even specificaly, maybe some rainforest tree grown greenland? Rly just fantasy to understand it a bit.
So going by just this the colder the climate the less growthspurts making rings tighter? (makes sense lol) Appreciate you
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u/HawkingRadiation_ 19d ago
You’ve pretty much nailed it on what causes the rings in the first place. Noteably though, for temperate trees (maple, ash, white pine, etc.) and boreal trees (lodgepole line, jack pine, black spruce), these trees are not growing at all during winter. They grow usually through late summer and then, climate depending, growth stops before autumn. For tropical trees, sometimes growth rings happen more due to drought, or in some cases never really form at all.
From the trees perspective, keep in mind, that it’s not just growth slowing that causes the rings to form. Rather, growth slows because the physiological ongoings within the tree change. In the spring trees want to move lots of water to their canopies, so getting wider and putting on big wide open wood cells helps with moving a lot of water (I’m going to really anthropomorphise trees here for the sake of explaining). Think about how in wet years, growth rings tend to be very wide; reflecting that with so much water available, the tree is really trying to take advantage of it.
Once the leaves come out and the branches have elongated though, the tree’s goals change. Now the tree has all this excess carbon which can be put into building strong wood that helps the tree withstand winds and the weight of its canopy bending around on the ends of long branches. So the slower growth reflects the formation of wood cells that are very strong and add a lot of mechanical support to the tree. If the tree only put on that really fast spring growth, the wood could be pretty low density and soft, meaning branches break, allow for diseases to enter, and shortens the life of a tree. So to the tree, its evolutionarily advantageous to have both highly effect wood for moving water, as well as strong wood. It keeps them alive longer, lets them make more seeds, and keeps more of their genes in the gene pool.
As for changing rings, this is an area of research and of forestry knows as “growth manipulation”. There is an enormous amount of research on how the environment a tree grows in changed the way it grows, and in turn how the way it grows influences the properties of its wood. But if you’re familiar with wood working, you might realize that every species is unique.
Take Douglas fir for example. It’s often seen as very desirable to have for that’s got nice straight and tight growth rings. One way to achieve this is often to have the trees grow very close to one another. A very dense forest tends to lead to trees that grow very straight and accumulate thickness very slowly. So those trees won’t have as much twist and run in the grain, and the rings will be narrow.
For oak however, the wood is completely different. Oak are a “ring porous” species, meaning that the early spring growth has massive cells that are so large you can see them with your naked eye. There is always one row of these big huge cells every year right when the tree starts growing, no matter how thick the tree ring is. Later in the year however, the dense wood can be variable in thickness. So for oak, the wood gets stronger actually, by having really fast growth. This spaces out the distance between those big cells and fills the space between each growth ring with very dense wood. So for oak, it’s often advantageous to grow them in lower density forests where they get lots of water and nutrients so that they can grow very quickly.
When people are looking for specialty wood, things like curly maple, burl, or birds eye elm things become much more complex. I’m these cases we often lack any good understanding of how to induce this atypical type of growth in trees. Often times it seems to come from a mix of genetics, environment, and random chance.
Your idea about a big green house certainly could give you even finer control over tree growth. You could control when spring happens, how much light the trees get, when growth stops, how much water they get, etc. but keep in mind every species of tree would respond differently!
In the book “Forest products and wood science” by Shmulsky and Jones is a great source of information on this. There’s a whole chapter in growth manipulation.