For the many new homeowners on wooded lots in the past five years, you may have a different problem: Trees already damaged or stressed from construction. I will make you this promise, “Help is on the way” (no, I'm not running for office).
Construction damage to trees can include several different things. Direct physical damage to the main trunk, severed roots from excavation, raising or lowering of soil grade around the tree, broken limbs in the crown, and soil compaction in the root zone can all affect tree health.
I want to cover, in some detail, the most overlooked problem in our list above. Soil compaction. At the beginning of the actual building process, the first thing a builder has to do is remove the topsoil from the building site. In a wooded setting, this layer of topsoil has an accumulation of leaves and twigs that are constantly being composted by beneficial fungus and bacteria that are providing nutrients to the trees as well as holding moisture in the tree's root zone. The removal of this layer not only destroys this natural process, but also leaves a bare layer of sand or clay. Soil compaction is not much of a problem in sand, but in clay soils, it is a serious problem. Prolonged truck and equipment traffic over the root zones lead to significant compaction and dramatically reduced water absorption.
Now lets talk remedies for this problem. Mulching as much of the root zone as possible, is one of the most effective treatments. 3 - 4 inches of mulch helps hold moisture and loosen soil as the mulch decays (remember the wooded setting).
Another damaging side effect of compaction is oxygen depletion to the roots. A practice called vertical mulching drills a grid pattern of holes 8 – 12 inches deep in the root zone and back fills them with compost or peat moss to improve water supply and oxygen penetration.
In severe cases, another method available is radial trench aeration. A spoke pattern of trenches going out from the trunk are installed using a specialized air trenching tool which removes soil without harming roots. These trenches are then back filled with topsoil or compost.
We don't want to overlook the obvious in all of this. A regular watering schedule until the tree recovers is a must.
Remember the beneficial fungus and bacteria that exist in woodland topsoils? In recent years, scientists have figured out how to reproduce and replace these organisms in the soil and restore the natural balance that existed prior to construction. A specialized soil inoculation can help remedy this problem.
Broken limbs can be pruned back to the next undamaged limb, and trunk scars can be repaired and treated by a qualified Arborist to ensure proper healing.
As with any health problem, the sooner help and treatment are sought, the better the chances of survival for your trees. Half the battle is knowing that you can do something for your stressed trees, the other half is not waiting.
Russell Hodge is a Certified Arborist and can be reached by e-mail at email@example.com.