View Mobile Site

Getting to the root of the matter

Posted: June 8, 2012 5:06 p.m.
Updated: June 11, 2012 5:00 a.m.


The most unseen and albeit most important part of a tree are its roots. Without roots trees would not be able to stand up much less stay alive and growing.

In general, trees have two types of roots: woody and fibrous. Woody roots can grow very large, live for the lifetime of the tree and are responsible for structural stability as well as nutrient and water transportation to other tree parts. The woody roots contain lignin which makes them strong and dense to keep a multi-ton tree upright. They also, like the tree trunk, grow in diameter in each year forming growth rings. For the most part, roots occupy the upper 12 to 18 inches of soil or less, so when you see roots of a mature tree ‘coming up’ out of the ground it’s a good sign and means they are growing to keep the tree grounded.

Fibrous roots are very small and temporary and generally occupy the upper 6 to 12 inches of soil or less. They may only live for a few months and the tree is always growing more. Don’t think that because they are small, they are not important. These hair-like roots are responsible for water and nutrient absorption and transportation and gas exchange. Without the fibrous roots the tree would be dehydrated, malnourished and eventually die.

I share this tree biology and anatomy 101 because if you have a tree in your yard it’s important for you to know the four limiting factors to root growth and why it matters. A healthy root system grows where there is (1) oxygen, (2) water, (3) nutrients and (4) space. If one or more of these qualities are lacking a tree will become stressed, unhealthy, prone to insect pests and disease, develop branch dieback and eventually slide into an irreversible decline to death -- how depressing. On the flip side, if all of these components are in adequate quantities for a particular tree species, it is healthy and grows great.

So where do roots find these factors needed for growth? In general it’s the soil, but many times the answer lies in the space next to walls or other infrastructure or underneath sidewalks, curbs and pavement. This soil-to-hardscape interface tends to be well aerated, the soil is less compacted and water readily seeps in -- providing a good environment for root growth.

By now you may be thinking, OK get to the point! Hang on here it comes…. Such was the case of a home here in the city where several mature live oak trees grow. Their woody roots expanded in diameter over the course of decades under an historic brick wall until the wall not only cracked in several places but was heaved up and is now leaning.

It was evident upon inspection of the site, that tree roots were the cause of the wall damage, but which roots and exactly where were they? The trees were about 2 to 3 feet away from the wall, too narrow a space to trench, which is not ideal as it would damaged all of the roots. A wonderful alternative to trenching roots is to excavate the soil by using an air spade. This relatively new arboricultural tool can be used for a variety of purposes such as soil de-compaction and aeration, soil amendment, excavation to examine for root rot, new tree planting and more. The uses are limited only by ones imagination.

Sox & Freeman Tree Expert Company in Columbia was called to perform root excavation using the air spade method. Amazingly enough, the air spade pulverizes and blows out the soil without damaging the roots. This allows a thorough look at the specific woody roots growing underneath the wall. Once identified, the roots measuring 4 inches in diameter and larger were cut to prevent any further damage to the wall.

Will cutting those particular roots kill the trees? No. Will the roots grow back? Fibrous roots will sprout out along the edges of what was cut but the root will not ‘turn back into’ what it was. Will cutting the roots structurally compromise the trees? Not likely. According to Dr. Kim Coder with the University of Georgia, a general rule of thumb regarding woody roots is not to cut more than four roots that are 4 inches in diameter or larger.

As with trees and utility line conflicts, tree root and hardscape conflicts exist anywhere the two meet. Short of tearing down the historic wall, which the homeowner was not going to do, or cutting down the trees, which the city was not going to do, this seemed like the best compromise for the situation at hand.


Interested in viewing premium content?

A subscription is required before viewing this article and other premium content.

Already a registered member and have a subscription?

If you have already purchased a subscription, please log in to view the full article.

Are you registered, but do not have a subscription?

If you are a registed user and would like to purchase a subscription, log in to view a list of available subscriptions.

Interested in becoming a registered member and purchasing a subscription?

Join our community today by registering for a FREE account. Once you have registered for a FREE account, click SUBSCRIBE NOW to purchase access to premium content.

Membership Benefits

  • Instant access to creating Blogs, Photo Albums, and Event listings.
  • Email alerts with the latest news.
  • Access to commenting on articles.

Contents of this site are © Copyright 2014 Chronicle Independent All rights reserved. Privacy policy and Terms of service

Powered by
Morris Technology
Please wait ...