As urban areas expand, many residential and commercial sites are being developed in the midst of trees to take advantage of aesthetics and environmental value of wooded lots. Unfortunately, the processes involved with construction can harm trees nearby. In the extreme case, trees may immediately die, or they can decline over a period of years. Taking the right measures to preserve the health of these trees can add value to wooded property.
Trees, like the one at left, can be damaged by physical wounds or environmental changes that impact the trunk, crown, roots, or whole tree. Physical wounds, such as a wound to the trunk or limb that is broken out, are usually apparent; however, less apparent are wounds to the roots caused by trenching, grading and digging. Environmental changes, such as adding fill-dirt over thr roots, paving, or compacting the soil may not be so apparent but can kill a tree over time. The act of removing unwanted trees on wooded lots changes environmental conditions for remaining trees, exposing them to excessive wind and sun which could cause wind-throw or sun-scalding. The ability to repair construction damage is limited.
The single most important measure a homeowner can take is to set up construction fencing (a no disturbance zone) around all trees they want protected. Allow one foot of space for each inch of trunk diameter.
Trenching Damage Demonstration
Eighty-five percent of a tree's root system is within 18-inches of the surface. The tree plots in the demonstration were part of a research project designed to determine the effects of "trenching" too close to shade trees.
For this research there were ten shade tree groves which were "trenched" to simulate a common construction practice. The trenches were 3 feet deep, 6 inches wide, and ran in a straight line between the white poles scattered throughout the site. The groves contained Sugar Maple, Pin Oak, or Ginkgo trees, and there were similar numbers of each species represented within the tests. The amount of tree root damage varied with the distance of the trench from the base of the tree. This treatment was designed to determine the effects of trenching near shade trees and, for the long-term health of the tree, how close is too close to dig a trench.