Felling a severely leaning tree sounds safe and easy. After all, what could the tree do other than fall in the direction it leans? In reality, a severe lean in a tree creates unique hazards that could severely compromise the trees stability as you are cutting, creating one of the most dangerous situations imaginable. While this danger can never be fully mitigated, the safest way to fell a severely leaning tree is to plan carefully and cut the tree using a bore cut to mitigate the risks of catastrophes like barber chairs. In this article, we will discuss the step-by-step process of felling these dangerous trees and explain the associated risks, so you can know what you are up against and plan accordingly.
The Dangers of Severe Leans
Severe leans (which I will somewhat arbitrarily define as leans beyond 7°), present great and unpredictable dangers in excess of what could be expected with only a slight lean. The danger comes most notably in the increased likelihood of “barber chairs,” which is when the main stem splits as it is falling. One half remains attached firmly to the stem and acts as a fulcrum while the other half swings back catastrophically toward the feller. You can see a representation of a barber chair in the informational video from WorkSafeBC below.
The specific likelihood of a barber chair varies considerably by lean, species, and the presence of structure-compromising defects like cracks and holes. If a tree is both leaning and defects are present, the risk of a barber chair is high.
Don’t Try to Fell Against the Lean: It’s Too Risky!
If you are reading this article, there is a good chance you might be considered a novice. Thus, given the increased risk of barber chairs and the capacity for unpredictability when felling severely leaning trees, it is not wise to attempt to fell the tree against the lean. Doing so introduces a lot of difficulty into the task and substantially increases the likelihood of things going awry.
While slight lean can be overcome with the use of felling wedges (you can read more about felling a tree against a slight lean here), overcoming severely lean requires the use of pull lines and other advanced techniques. If you need to fell a severely leaning tree against the lean, it is best to hire a professional.
Step 1: Assess the Situation Carefully and Make a Plan
As when felling any tree, it is crucial to carefully assess the situation and determine a plan for felling. Begin by examining the tree and ascertaining its physical condition. Leaning trees are usually more stressed than others, so they have higher rates of defects and rot. Ensure the tree is sound. If the tree is rotten, read our article on felling dead and rotten trees here.
Next, look up in the canopy and check for any hanging branches or crown entanglements. Make an informed judgement of how the presence of these factors affects the safety of the situation.
Once all factors have been identified and considered, determine the best direction of fall. While you should avoid felling against the lean, you can adjust from right to left within about 45 degrees on each side. Just be sure to account for the displacement of the top of the crown from the base when determining whether there is enough of an opening in a given direction for the tree to fall freely. If the crown is displaced 10 feet, you can expect 10 feet of displacement from the expected trajectory.
Finally, it is crucial that clear escape routes are established. These escape routes will allow you to retreat in the event of unplanned movement during felling. These routes should be located 45 degrees off from the opposite direction of felling, as seen below. Clear these paths of any brush and debris.
Step 2: Cut the Notch as You Normally Would
The notch on a severely leaning tree will be no different than on any other tree. Any style of notch can work, but we recommend the open face notch for its increased safety and (possibly) reduced risk of barber chairs. Given enhanced risks, it is beneficial to keep the tree attached to the stem for as long as possible during the fall, and the open face notch accomplishes this.
Step 3: Bore Cut the Tree and Set the Hinge
The key to safely felling a severely leaning tree is the bore cut. A bore cut (also known as a plunge cut) is when you start the back cut from the inside out, using the tip of the bar to essentially drill through the tree. This allows the tree to remain firmly attached to the stump until you are ready to let it fall. The safety offered here is extremely important.
When you are felling a severely leaning tree, gravity is on your side. Usually, this is good, but when the lean is extreme, gravity can be a bit over-zealous. If you use a traditional back cut and come in from behind, gravity may bring the tree down before you are ready, and if it starts to fall while the hinge is still too thick, the tree may split up the stem, resulting in a catastrophic barber chair.
Bore cutting, on the other hand, allows you to carefully set the hinge and take your time with the technical aspects of felling without gravity pulling the trigger before you are ready. The tree remains attached from the back the whole time. While bore cutting does not eliminate the risk of felling a severely leaning tree, it greatly, greatly reduces it.
Unfortunately, bore cutting takes practices and a fair amount of skill. To learn how to properly bore cut and hone those skills, read our article on the subject here.
Step 4: Cut the Back Strap and Be Prepared to Retreat
Once the bore cut is made and the hinge is set to proper thickness, all that remains is to cut the back strap and release the tree, but double check everything first. While the bore cut has reduced your risks, do not get comfortable, there is still much that could go wrong in this final step, so once the final cut is made, retreat slowly toward the escape routes. Do not stand next to the tree as it falls. If it looks like the stem is beginning to split, retreat even further. But in the midst of taking these cautions, don’t forget to enjoy the incomparable satisfaction of watching your tree fall!
While the steps mentioned here are the best practices and will greatly reduce the risks of injury or death, these risks cannot be eliminated. The most important safety tools you possess are your common sense and capacity for humility. Assess the situation rationally and carefully, and be honest about your comfort level. If you aren’t comfortable felling the tree, don’t! It’s not worth it. Build up your skill on trees with lower stakes.
Stay safe and have fun.