Most city trees are transplanted, although there are of course exceptions. A city park created from the original countryside may contain the original trees. A development laid out by a superior builder in conjunction with a landscape architect will contain as many of the original trees as possible. Trees are a valuable asset and take years to reach full growth.
The best size tree for normal transplanting has a trunk diameter of 2 to 3 inches and a height of 10 to 12 feet. Trees of this size are large enough to improve the landscape and to survive the shock of moving. Normally the ball, or roots, measure in feet what the trunk diameter measures in inches. If it is necessary for you to transplant a tree, keep two points in mind:
1. Measure and specify sizes correctly. The size of a tree in indicated by its caliper (diameter of trunk), height, and ball size. Example: a 4 inches caliper 16 feet high and a 4 feet ball size.
2. Estimate the weight of the ball so that you will not be surprised and encounter handling problems. To estimate, square the diameter of the ball, in inches; multiply the result by the depth of the ball, in inches; subtract one-third from this amount, and multiply the result by 0.075.
For example, let us estimate the weight of a 2 feet ball with a 20 inches depth:
242 X 20 = 11,520
11,520 ─ 11,520/3 = 11,520 ─ 3,840 = 7,680
7,680 X .075 = 576 lb
This is no small weight, and when you realize that a 3 feet ball with a 30 inches depth may weight close to a ton, you will appreciate how important it is to have on hand the manpower and equipment to handle the weight.
Sometimes in order to obtain special immediate effect, full-sized trees must be planted. This can be done successfully if the trees are given special handling and if the ball size is kept in proportion to the caliper. For large trees, 6 inches to 10 inches caliper, the ball size should be 6 feet to 10 feet in diameter.
After transplanting, trees should be wrapped to prevent sunburn, and then protected by tree guards. These tree guards may be elaborate wrought-iron constructions or simple wire fencing. The important thing is to guard against vandalism.