I’ve heard the way to manage timber is to “cut the big old trees and leave the small young trees to grow into big old trees and then do it all over again in about 10 to 20 years or so”.
That method of tending the forest sounds intuitive enough and quite good and reasonable, but unfortunately in our oak and pine forest systems, its just not that simple, and quite frankly, slowly degrades forest production and quality.
In a generally even aged forest (for which most of the central hardwood forest is comprised) its important to understand first, how these 4 concepts below interact:
- How trees grow
- Shade tolerance
- How trees interact with each other
- Tree age
How trees grow – Trees are like factories, where production is dependent on how many workers (leaves) can gather sunlight, convert carbon, and store it in the warehouse (trunk or stem) as wood.
Shade tolerance – Not all trees respond to light and shade the same way throughout their lifespan.
How trees interact with each other – If a tree doesn’t have enough light it will either not grow at all and die, or it will grow slowly and with poor form.
Tree age – Certain species of trees will only live to a certain age range, and must interact with other trees to gain a competitive advantage to become a large productive tree.
If two or more trees start as seedlings with plenty of light, generally a few of those trees gain advantages by either genetic superiority or a localized patch of good soil to get started. Once those few trees gain the advantage, the advantage carries with them through most of their growth and life.
More sunlight means more workers (leaves) to invest in, and therefore bigger roots, more branches to support more leaves, more height, more sunlight to catch, and the process gains traction from there into a big dominant tree.
The trees that don’t gain the competitive advantage early, fall further and further behind and go into survival mode, which means they only invest in enough leaves and growth for the limited light it receives under the shadow of the bigger trees.
For these suppressed trees, this means less branches, smaller root systems, and ultimately a smaller stem. These trees do this and ride it out until they don’t get enough sunlight at all and die, or until they reach the end of their lifespan (maturity) and then die. Often times, these suppressed trees are mistaken for younger trees, and its assumed that if given room to grow, they will grow into a big old tree.
Lets look at a live example:
If a black oak tree can only live 90 – 100 or so years on a fair growing site, then both of these trees only have 10 to 20 years left to occupy the growing space.
There are many factors to discuss here, and many of them to long winded for a blog post, as if this post wasn’t already long winded enough. But a few take home points from all this information would be:
- Don’t assume a small tree is a young tree, and it will grow big if you cut the big tree next to it. Often times, it wont!
- Evaluate which trees to cut in a stand based on their ability to provide the most return and value for you and wildlife in that limited growing space for the long haul.
- In an oak forest, don’t let suppressed trees get to old or die before they are cut. Oak trees can sprout from a cut stump using the existing root system and will contribute as a future tree in the forest. If a tree dies, the root system dies with it. Use that process to your advantage.
- Use a trained forester with experience to help you manage your timber. It pays now and into the future!