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Bulldozing has been mentioned as a threat to tree roots. Not only the blade and crushing treads are to be feared. The machine's mere weight can so impact the soil that it becomes impervious to air and moisture. And in grading, any overlay of soil more than three or four inches deep is likely to suffocate the sturdiest root systems. A Canadian doctor named Locke used to ascribe most human ailments to deformations of the feet, brought on by wearing badly designed shoes. Some dendrologists similarly believe that more tree ailments than we suspect are caused by root deformations. Commonest of these, and easiest to discover and correct, are so-called "girdling" roots, where one crosses and constricts another close to the trunk, or constricts the trunk itself. The effect on the tree's circulation is precisely that of a tourniquet around your leg, or a noose at your neck. Any home owner with a pick and shovel can expose such conditions for himself. When they are not visible above ground, their presence can be suspected wherever one side of a trunk comes up straight out of the ground without the flare of buttress roots. For a typical case of detection and exposure, see Photos. 3, 4, 5. |
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