Getting to the Root of the Problem
Tree roots are often the most overlooked, neglected, and abused component of the tree’s anatomy. Tree root problems are a major part of a tree’s health.
In the mid-Atlantic region, tree roots are located mostly in the top six to ten inches of soil. This is due to the abundance of clay and rock. Because there is not a deep layer of topsoil, roots will “pancake” out horizontally rather than grow downward. Believe it or not, roots can often extend two to four times the diameter of the tree’s drip line (the area below the canopy, or branches, of the tree).
Functions of Tree Roots
Tree roots perform critical functions. They provide structural stability by keeping tons of trunk and canopy upright. They also absorb the necessary water, nutrients, and oxygen that every living cell and tissue within the tree must have in order to survive and function. Clearly, without a healthy root system, the tree cannot be healthy.
Roots provide stability to trees. They spider-web out into the soil as they attach to rocks, crevices, and whatever else they can in order to hold the rest of the tree upright. Considering how much stress is caused by the force of heavy winds that can catch thick canopies like a sail, it is amazing that roots are able to keep trees upright. This ability is greatly reduced in cut, diseased, or damaged roots.
If we take a good look at how roots grow naturally in the forest, we can begin to see why they have such a hard time in urban environments.
Soil conditions in the forest are significantly better. Leaves and twigs are allowed to decay where they fall, recycling nutrients and organic matter back into the soil. Therefore, over time, topsoil tends to become deep and rich. The forest floor is alive with microorganisms, earthworms, and mycorrhizae (a symbiotic root fungus that increases root absorption). The physical structure of the soil also allows oxygen into open-pore space where it can be absorbed easily by roots.
Trees growing in groups, as we see in the forest, often share resources. Their roots live in a symbiotic relationship, and they are able to share water and nutrients.
Trees Growing in Urban Environments
Urban trees tend to grow by themselves, with their root systems covered by a thick and unyielding layer of grass that competes for available water and nutrients. Soil conditions are harsh and hardly conducive to healthy root growth and function. Compaction squeezes out open-pore space, thereby reducing available oxygen and water levels. Leaves and twigs are removed so they are unable to add organic matter back into the soil.
In fact, during new construction, topsoil is usually removed, and the original grading is drastically changed. Everything from soil ecosystems to water flow is affected. Additionally, grading often removes large portions of root systems.
Tree Root Problems
As vital as they are to the health and survival of trees, roots are often the victims of mostly unintended but sometimes severe abuse. They may be forced to grow in a space that is far too confined for the size of the tree. They are often cut, compacted, drowned, starved, and poisoned; damaged by lawn mowers, weed whackers, cars, and construction crews; and otherwise abused in the urban setting.
Tree root diseases that include Armillaria (also known as shoestring root rot), other forms of root rot, vascular wilts, and various pathogens can cause considerable damage to roots. Because they exist mostly below ground, these problems can be hard to see and diagnose. Severe cases can sometimes be seen above ground.
Tools such as the Air-Spade are now available to help the arborist expose and view the root system without causing damage to it. The Air-Spade also allows poor, compacted soil to be replaced with nutrient- and mineral-rich organic soil amendments.
Tree root problems are sometimes caused by improper planting. Root girdling, which may be caused by burlap that was left around the root ball or by soil added during planting, can eventually choke off a treeʼs vascular system by causing roots to grow in a circular pattern around the root ball. Additionally, planting a tree too deep often makes it hard for new roots to grow into the surrounding soil. Deep planting can result in roots growing from the side of the trunk rather than from the root flare.
Mulching Your Trees
A two- to three-inch layer of wood-chip mulch spread out over the tree root system can have many advantages, but only if it’s applied correctly. Mulch should never come into contact with the trunk and should not be piled up “volcano” style. Wood-chip mulch is the recommended mulch to use because it breaks down naturally and controls weeds better.
Double-shredded mulch can glaze over, which creates an impermeable barrier that prevents water from reaching the roots below. Wood-chip mulch protects roots from mechanical damage from lawn mowers, regulates soil temperatures, and holds moisture in the root zone. Spread it over the root system as far as practical. Try to go as far as the drip line of the canopy, and you’ll go a long way toward alleviating the competition problem created by sod over the root system.
To care for your trees from root to canopy, contact Growing Earth Tree Care today.