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Mr. Stout's measurements, ring counts, and other data were illuminating not only to dendrologists. They also contained broad hints for home owners. Most importantly they revealed that the average tree's root-spread is far wider than had been supposed. Instead of approximating their crowns' spread, the roots of Mr. Stout's trees reached out into areas 3.4 to 40.7 times as great as the ground-space under the crowns. (See Photo. 2 and diagrams following p. 48; also diagrams pp. 15Q, 160. Dotted lines show crown areas, as contrasted with root reaches in solid line. Graphs give stem (—0—) and root (—x—) growth data in feet and years. Circles initialed CO, WO, RM, etc., denote neighboring chestnut oak, white oak, red maple, etc.) Eighteen of the trees appeared to have normal root systems; for these, the root-crown ratio averaged 4.5 to 1. Since the Black Rock trees had grown under forest conditions, with their crowns touching, this meant that each tree was competing for sustenance with at least three of its neighbors. Where adjacent trees had been removed by natural death or foresters' thinning, in known years, the trees under study had responded, as shown in growth rings, by quickly extending their roots as well as their branches. Roots were found to vary surprisingly in age. And some of the younger ones were among the longest. "The many-aged nature of the roots," wrote Mr. Stout, ". . . suggests that throughout the life of a root system there is a continuous process in which the old roots die off and new roots emerge. If this is the case, then there would be, coming from the stump and major laterals, waves of new roots that would occupy and reoccupy the soil." |
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