Protecting Trees During Construction
In order to preserve mature trees during construction, a careful plan must be created to protect their trunks and root systems from construction site injury.
Before construction begins, do an inventory of the trees, noting their present condition. Donít try to save an unsafe, unhealthy tree. After the inventory, a firm decision can be made about what trees are to be saved, and the location of the house, pavement, utilities can be determined. Draw up a plan which confines the sidewalks, driveway, construction vehicle access, utility trenches, grade changes and work areas to the smallest area possible. Any trees that remain within this area should be removed before construction begins. Be realistic; it is not possible to save every tree. Lastly, all of the contractors must guarantee to respect the tree protection zones throughout each phase of the construction, no exceptions.
Because most tree roots are concentrated in the upper 6 to 18 inches of soil, excavation, foot or vehicle traffic, material storage, contamination, and grade changes can all cause serious damage. Thus, the secret to protecting a tree during construction is to protect its root system. A treeís roots extend out horizontally from the trunk toward the outer edges of the canopy, or even farther. This, then, is the zone that must be protected during construction. First, fence the area off to shield the soil around the tree from any disturbance; additionally this protects the trunk from mechanical damage. Apply at least 4 inches of mulch over this entire area. The mulch will create a forest floor environment that will help protect the root zone. As the mulch decomposes, it will recycle nutrients naturally. Add more mulch as necessary. This protective zone is an absolutely no disturbance zone.
All dead wood in the tree should be pruned out, and the tree should be thinned in order to reduce the amount of leaves and branches that the tree must support while under stressed conditions.
Before, during, and after construction, the tree should be watered to a depth of 12 inches during periods of low rainfall, since the shallow tree roots are very sensitive to drought stress. Watering regularly after construction will help the tree recover from construction shock. Donít fertilize the trees as long as growth continues and there are no apparent nutrient deficiencies. Fertilizing could encourage excessive top growth and create additional stress for the tree.
After the construction is finished, continue to monitor the health of the mature trees. Let each tree recover at its own pace. Even with the best protection, a tree may take 3 to 5 years to recover from construction shock. For more information about protecting trees during construction, please call the Extension Office.