Plans to preserve trees during construction should coincide with your initial planning of the structure. Before you build, consider the trees that are important to you and keep them in mind when you locate the building, garage, and driveway. Make sure to identify tree species on your lot before beginning to build. Knowing which species thrive in shade, or which species can withstand root cutting or insects and disease can help guide your decisions about which trees to remove or save. Also consider the vigor and health of individual trees when you decide which trees to save. It is best to save trees in good health. If you have difficulty determining the health of a tree, a certified arborist can help you.
While branches and bark may break and tear during construction, the greatest damage to trees will occur at the roots. Roots are responsible for nutrient and water uptake, as well as storing energy and anchoring the plant. Therefore, it is essential to prevent root damage when building. Before construction, calculate the "Protected Root Zone" and place a physical barrier around this zone for each tree you wish to save. The "Protected Root Zone" is the portion of the root system directly below the branches of the tree, also known as the "dripline." For more information on this, as well as information on other methods to preserve trees during construction, please visit Protecting Trees From Construction Damage, A Homeowner's Guide.
Information taken from "Protecting Trees From Construction Damage, A Homeowner's Guide" and from Tree City USA Bulletin No. 7: "How to Save Trees During Construction"