A leaning tree presents a significant risk during felling because its center of gravity is biased, making its movement highly unpredictable. Gravity creates immense tension on the side opposite the lean and compression on the side of the lean. This bias means the tree may split upward prematurely—a dangerous event known as a “barber chair”—or fall immediately without warning or control once cutting begins. Felling a leaning tree is an advanced procedure requiring specialized knowledge and equipment. Any large or severely leaning tree should be handled exclusively by professional logging services.
Essential Safety and Site Assessment
Preparation for felling a leaning tree begins with rigorous adherence to safety standards and a thorough assessment of the environment. Personal protective equipment (PPE) is mandatory, including a hard hat, hearing protection, safety glasses, and chainsaw-resistant leg protection, such as chaps. The immediate area around the tree’s base must be cleared of brush, rocks, and debris to ensure stable footing and prevent tripping during the cutting process.
Determining the true direction of the lean is a crucial preparatory step, as it may differ from the desired direction of fall. This assessment can be done visually by stepping back a distance equal to the tree’s height, or more precisely using a plumb line or a level held against the trunk. Once the intended direction of fall is established, two clear escape routes must be planned and cleared. Each route should be positioned at a 45-degree angle away from the line of fall and extend for at least 15 to 20 feet. These routes allow for rapid, safe retreat immediately after the final cut.
Specialized Tools and Techniques for Directional Control
Successfully directing a tree against its natural lean requires mechanical aids to overcome the existing gravitational force. Felling wedges are fundamental tools, providing a lifting force that helps shift the tree’s center of gravity toward the desired direction of fall. These plastic or aluminum wedges are driven into the back cut, applying pressure to the wood fibers and creating torque that pivots the tree around the hinge.
For trees with a significant lean, mechanical pulling systems are often necessary to apply tension before the final cut. This involves securing a strong rope or cable high up on the trunk, ideally at least two-thirds of the way up the tree’s height, and connecting it to a winch or specialized felling jack. Attaching the system high on the trunk maximizes leverage, allowing a smaller applied force to generate greater felling force. This manipulation maintains the center of gravity over the notch, providing directional control despite the tree’s bias.
Detailed Steps for Making the Felling Cuts
Felling a leaning tree safely requires the use of an open-face notch, which provides superior directional control. This notch is created by making a sloping cut followed by a horizontal cut on the side facing the intended fall direction. The angle of the open-face notch should be 70 degrees or greater, ensuring the hinge remains intact until the tree is almost on the ground.
The notch depth should be 20% to 25% of the tree’s diameter. The hinge wood—the uncut fibers between the notch and the back cut—should be uniformly thick, typically 10% of the diameter. The hinge acts as a pivot and steering mechanism. For a leaning tree, maintaining a precise, intact hinge is critical to prevent the trunk from splitting vertically, which causes a “barber chair.”
Bore Cutting Method
The most specialized technique for a leaning tree is the bore cutting method, used to create the back cut. This technique involves plunging the nose of the saw bar into the center of the tree, starting slightly behind the intended hinge line and running parallel to the horizontal notch cut. The safest way to bore is by using the bottom quadrant of the bar tip to minimize the risk of kickback.
The bore cut is advanced through the trunk, leaving the hinge wood intact at the front and a small section of holding wood, or “back strap,” at the rear. This establishes the hinge before the tree’s weight is fully transferred. Wedges can then be inserted and secured into the bore cut opening before the final fibers are cut. Once the wedges are in place, the saw is used to cut the remaining back strap, and the wedges are driven further, forcing the tree to pivot and fall under controlled tension.
Contingency Planning and Dealing with Hang-Ups
A contingency plan is necessary for the high-risk event where the tree becomes lodged in another tree, creating a “hang-up” or “widowmaker.” If the tree becomes lodged, the immediate action is to disengage the chainsaw and retreat rapidly along one of the two pre-cleared 45-degree escape routes. Never turn your back on the tree as you retreat, and continue to monitor it for movement.
A hung tree is dangerous because it can drop or roll without warning. Attempting to dislodge it by cutting the supporting tree, cutting the hung tree at the base, or climbing the hung tree are strictly prohibited practices. The only safe methods involve applying mechanical force from a distance.
Safe methods include using a tractor or winch with a long cable attached high on the trunk to pull it free. Alternatively, specific rolling tools, such as a cant hook, can be used to rotate the lodged trunk off its support point. This must be done while working from the butt end of the tree to maintain a safe position. If a hung tree cannot be safely brought down, the area must be clearly marked and cordoned off until a professional arborist can remove the hazard.