Deciding which trees to harvest and when is an important part of getting what you want from your forest. Following the right guidelines will ensure that you will get what you want now and well into the future.
When my sister and her husband purchased some wooded property in Vernon County a few years ago, they asked me take a look at their woods and give them some advice on how to manage their trees. My first questions to them were “What do you want to get from your forest? Do you want to attract wildlife? Sell timber? Harvest firewood? Enjoy the scenery?” They responded with a resounding “YES!” They also indicated they wanted to do the work themselves, something I often encounter when working with woodland owners.
So we walked their property and I described a number of things they could do to enhance their woodlot and achieve the broad set of goals they identified. They were particularly interested in learning about which trees to cut down and which to leave, so I walked them through some simple guidelines which I will share with you here. For starters, felling trees can be a dangerous operation with unexpected consequences, so wear the proper safety equipment and, if you can, take a chainsaw safety class.
I like to think about reducing competition when deciding which trees to cut and keep. Trees are constantly in competition with each other for space, light, water, and soil nutrients. The less competition the trees you want to keep (also called crop trees) have, the healthier they will be and the more they will grow. For a mature stand of hardwood trees like oak and maple, that might mean felling trees on two sides of the tree you want to keep. This provides growing space for your remaining tree while not making it vulnerable to being knocked over by a strong wind storm or a heavy load of ice and snow. For a fairly dense stand of small to medium sized trees (also called poles), you might want to remove more trees around the trees you want to keep so they reach maturity a bit faster. These strategies are not too difficult to implement, and mimic the kinds of processes that are taking place naturally within a stand of trees.
The hard part of this activity is figuring out which trees to keep and which to cut. To start, think about which species fit with your goals for your woodlot, and favor those when deciding which to keep. That might mean keeping oaks for their acorn production (to attract wildlife) or keeping maples for their fall colors. However, I suggest keeping a few trees of each species, as diversity within your woodlot is always a good thing.
Now that you know which species you are favoring, it is time to decide which trees to remove. Some things to keep in mind are form, health, and function. The form a tree takes can make a big difference in how useful it is in meeting your goals. This is especially true if you are managing for trees to be made into lumber and veneer. If that is your goal, then favoring straight trees with few low branches is the way to go.
Favoring healthy trees over those with some health problems is generally a good strategy to embrace. Unhealthy trees can be easy to recognize at times, but not always. Dead and dieing trees will have few small branches and leaves, might have different kinds of mushrooms growing out of them, and the bark might be falling off. Those are usually the easy ones to recognize. Some characteristics to look for that indicate a tree might not have a long life span include things like a large vertical crack in the stem which can be an indicator of a lightning strike to that tree. Also, if more than half of the branches in the crown of a tree are dead or dieing, then that tree likely will not live very long. Finally, trees can become stressed due to a lack of light, water, and soil nutrients. These trees will have reduced growth (both in height and number of branches) and are susceptible to insect and fungal attacks, and therefore might be a good candidate for removal.
Deciding whether or not to keep a tree due to the function it serves with your forest can sometimes conflict with the health and form characteristics I already mentioned. For example, you might have a very old oak tree with many branches and poor form that would be a good candidate to remove based on health and form criteria. However, that tree might be a great producer of acorns and provides homes for a wide variety of wildlife making it a great fit if your goal is to attract wildlife. Dead trees (or snags) are another example of this conflict. Snags attract insects that can infect your healthy trees, but they also attract woodpeckers and other wildlife that feed off of those insects. Having a bit of variety within your woodlot by including snags and poorly formed trees will help to achieve a wide variety of goals.
When we finished our walk through their woods, my sister and her husband felt better about choosing which trees to harvest and which to leave. They were definitely interested in learning more, so I suggested they visit woodlandinfo.org and view the publications available there and to check out the workshops being offered in their area.
We always recommed working with a forester when you are onsidering a timber harvest. Check out our publications Conducting a Successful Timber Sale and the Sample Timber Sale contract for more information.