The Trinitarian Controversy and the Problem of Shallow Roots
by Tom Chantry
I was looking at the enormous Norway Maple in my backyard the other day, and a question occurred. How deep are its roots? Living as we do in the age of Google, I soon found myself reading this fascinating and instructive article on the question of root depth.
Apparently there has been some dispute over the natural root depth of trees. Back in the 1930s, scientists investigated this question by digging out the root systems of large trees. The answer that they reached is one you may have seen in textbooks when you were a kid: that the root system of trees is as extensive as the branch system. Indeed, reports exist of such trees to this day.
However, this was not the end of the question. Many assumed that trees could not be grown in modern cities because the typical soil composition would not allow for the development of such elaborate root systems. It turns out, though, that those 1930s scientists had understandably chosen trees for their study which were planted in easily dug soil such as loess (sediment deposited by wind). The more diggable soil allowed for careful extraction of a tree’s root system. It turns out, though, that in such soil trees tend to grow deeper roots, but that the same variety of trees may also grow tall with roots stretching out horizontally.
Today, urban arborists often explain that trees don’t require deep soil, and common opinion has turned against the old deep-root theory. The correct conclusion, as expressed by James Urban of the American Society of Landscape Architects is this: “Trees are genetically capable of growing deep roots, but root architecture is strongly influenced by soil and climate conditions.” Specifically, soil which is compacted and has poor drainage creates a poor environment for root depth. This does not mean, however, that trees cannot grow, only that they may grow without deep roots.
Yet all may not be well. A tree may look tall, full, and impressive, but its root system may prove insufficient. A tree with shallow, horizontal……
Read the entire article here.