Answer: Tree root systems cover more area than one might expect -- usually extending out in an irregular pattern 2 to 3 times larger than the crown area. However, on a dry weight basis, the "root to shoot" ratio is around 20 to 80%, making the top four to five times heavier than the roots.
The type of roots formed initially is specific to a given species; with age the initial root form is often modified by the growing environment. Such thing as soil hard-pans, water tables, texture, structure, and degree of compaction all influence the mature root form. There are three basic classes of tree root systems:
Tap root (hickory, walnut, butternut, white oak, hornbeam),
Heart root (red oak, honey locust, basswood, sycamore, pines), and Flat root (birch, fir, spruce, sugar maple, cottonwood, silver maple, hackberry).
Most tree roots do not penetrate very deeply into the soil. Unless the topsoil is bare or unprotected, trees will concentrate most of their absorbing roots in the top 6 to 18 inched of soil, where water, nutrients, and oxygen can be found.
Hope this answers your question!
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