The practice of felling a tree safely and with directional control hinges entirely on the proper execution of the felling cut, which begins with the notch. The notch establishes the hinge and dictates the tree’s trajectory as it falls. Without a correctly cut notch, the tree can fall unpredictably, creating a hazardous situation where the trunk might split, kick back, or fall in an unintended direction.
Essential Safety and Pre-Cut Planning
Before cutting, mandatory personal protective equipment must be secured, including a hard hat, eye protection, and hearing protection. Chainsaw chaps are necessary, constructed with layers designed to stop a running saw on contact and protect the operator’s legs. Sturdy, steel-toed boots provide protection for the feet against dropped logs or falling branches.
The site assessment is the first step in planning the tree’s fall, which involves identifying the tree’s natural lean, the distribution of its canopy weight, and any potential hazards like dead branches or rot. Once the desired direction of fall is determined, a clear escape route must be established and cleared of obstacles. This route should be positioned at a 45-degree angle away from the anticipated direction of the fall to allow a quick and safe retreat immediately after the final cut is made.
Constructing the Conventional Open-Face Notch
The open-face notch is the safest and most commonly recommended technique for directional felling, as it maintains control over the tree for the longest duration of the fall. This notch is defined by its wide opening angle, which should measure between 70 and 90 degrees. This wider angle prevents the notch from closing until the tree is almost on the ground, maximizing the guiding function of the hinge.
The creation of this notch involves two distinct cuts that must meet precisely to form a clean apex. The first cut, the top cut, is made with a downward angle, around 70 degrees, and should extend into the trunk to a depth of 1/5th to 1/3rd of the tree’s diameter. The depth of this cut is directly responsible for establishing the length of the hinge wood that will remain.
The second cut, the bottom cut, is made with an upward angle, around 20 degrees, to meet the top cut exactly at the intended apex. It is crucial that the two cuts meet without crossing or creating a bypass, which would compromise the integrity of the hinge. Once the two cuts meet, the wedge of wood is removed, leaving a clean, wide-open face aimed precisely in the direction of the desired fall. The apex of this notch is the front line of the hinge, and its horizontal alignment across the trunk determines the accuracy of the tree’s trajectory.
Understanding the Humboldt Notch
The Humboldt notch presents a distinct alternative to the open-face notch, primarily differing in its geometry and purpose. In this technique, the bottom cut is angled downward, while the top cut is made horizontally into the tree. This reversed configuration results in a wedge of wood that remains attached to the log rather than the stump.
The main advantage of the Humboldt notch is that it maximizes the value of the butt log, the lowest and often most valuable section of the tree, by leaving the notch wood on the stump. The Humboldt notch is cut to an angle of about 45 degrees and is used on larger trees, particularly when working on steep terrain. However, the narrower angle means the notch closes earlier in the fall, providing less directional control compared to the open-face notch.
The Role of the Hinge and Back Cut
The felling process is completed by the back cut, which works in conjunction with the hinge to control the tree’s descent. The hinge is the uniform strip of uncut wood left between the apex of the notch and the back cut. This wood serves as the mechanical guide, acting like a door hinge to steer the tree precisely along the path established by the notch.
The thickness of the hinge should be 10% of the tree’s diameter at breast height. For example, a 20-inch diameter tree requires a hinge thickness of about two inches. A hinge that is too thin will break prematurely, leading to a loss of control, while one that is too thick may prevent the tree from falling fully.
The back cut is a horizontal cut made on the side of the tree opposite the notch, and it must be level and slightly above the apex of the notch. This slight elevation creates a step, known as the “stump shot,” which helps prevent the butt of the falling tree from kicking back or sliding off the stump toward the operator. Felling wedges are often inserted into the back cut as the saw approaches the hinge to help lift the tree and commit it to the fall direction, allowing the operator to safely retreat along the planned escape route.