This can be done to any size tree. When my ancestors were clearing land they would 'ring the trees' with huge cross cut saws. The thing to remember is not only cut all the way through the bark but on some trees you will have to make an inch wide cut, often accomplished with a nice little hatchet otherwise the tree will push sap into the cut and 'heal' itself. The best time for doing this is when the sap is down. If you do it when the tree is green the leaves will brown and look very ugly in a garden until bad weather pulls them off. After the tree dies it will be easier to cut. You will still have a living stump so you will have to cut any new growth before it can become a second tree.
