RES
ArboristSite Operative
I have always wondered why the manuals tell you to make the felling notch 1/3 the diameter of the tree and not more. When you make the notch the weight of tree above the notch is supported by the uncut lower portion. Therefore an overturning moment is created to cause the tree to fall towards the notch. When you begin cutting the opposite side and reach 1/3 that overturning moment no longer exists. From that point on the moment begins to turn the tree back towards the cutting side. It would seem to me that it would be better to make the notch 1/2 the diameter to avoid this from happening. The 1/3 notch seems to work. The only explanation that I would have is that when you make the notch, the overturning moment causes the flexible tree to shift its weight towards the notch. This is enough to cause the tree to fall towards the notch, even though the back cut is bigger.