A tree that develops a deep, strong root structure can withstand heavy winds without toppling to the ground. Its roots also help prevent soil erosion, especially along riparian areas that are prone to flooding. The roots of a tree continue to grow throughout the tree's lifespan, always expanding outward and downward in search of what the tree requires to survive. A tree depends on its roots to reach deep into the soil to search for the water and nutrients that it requires to survive.

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Oak trees do not tolerate transplanting well because of their deep root systems.

Tree Types and Their Roots

White oak, hickory, black gum, sassafras, sweet gum, Japanese pagoda, butternut and some pines develop deep taproots. During their first years of life, the trees display remarkably little top growth because all of their energy is focused on creating a deep and diverse root system. The American basswood, American hornbeam, boxelder, chestnut oak and the swampbay magnolia develop deep lateral roots. The lateral roots firmly anchor the tree to the ground.

Spread

A tree's most active roots occur in the top 3 feet of soil; some trees with shallow root systems have their most active roots in the top 12 inches of soil. Trees that develop deep taproots require well-draining soil. Most trees develop the majority of their roots laterally to about three times the tree's branch width, according to the North Carolina State University. In areas that suffer from compacted soil, the tree is often unable to develop a deep root system. Its weak root growth renders the tree unstable.

Taproot

Most trees require soil with adequate nutrients and soil. Trees that have evolved to produce a deep taproot can withstand soil conditions that other trees often fail in. They can tolerate drought and will survive in locations that other tree types often perish in. The taproot grows deep and strong. It does not always grow straight down but may grow in varying directions. The taproot forms small lateral roots off its length.

Planting Site Effects

A tree will adjust its root system to exist in the environment it is planted within. If the soil is rich and moist, the tree will not require a deep root system. In planting locations that often suffer drought conditions, the tree will produce a deep root system as it searches for the water it requires to survive. A tree with a deep taproot does not withstand transplanting well. Any damage to the tap root often causes the tree to die. Tree types that produce deep lateral roots will withstand transplanting well.