Some tree roots spread wide, don’t go deep

LITTLE ROCK — Q: When large deciduous trees were felled intact by recent storms, I was surprised to see only a small disk of surface roots and a thin plate of soil. What happened to the root balls and deep taproots?

A: “The vast majority of temperate forest trees do not have taproots or even very deep roots at all,” said Melanie Sifton, vice president for horticulture at the Brooklyn Botanic Garden.

In fact, she said, for most trees, the roots are concentrated in the top foot or two of soil.

The root system is more likely to expand horizontally, forming a flat, platelike mass far out beyond the tree’s canopy, or leafy zone.

Tree root systems are often categorized into three main types: plate- or surface-root systems, heart-root systems and taproot systems.

“While many temperate oak species are generally considered to have taproot systems,” Sifton said, “American elm trees, for example, are notorious for their shallow plate roots.”

Root patterns are also heavily influenced by the soil and the available underground space, she said.

To grow trees that will weather storms for many years, Sifton suggested, “give them a wide and deep space to put down roots and protect their root zones from damage and compaction.”