Construction damage of trees is one of the leading causes of structural failure and death of mature trees in the landscape. Proper planning and management of site conditions can improve tree survival and help identify trees that either should not be saved due to prior health problems, or will suffer too much damage from construction activities to be maintained in the long term landscape. Soil structure, root depth, existing infrastructure and weather conditions all play a role in tree conservation management decisions. Land managers can use these resources to identify problem areas and develop design and "best management" solutions for construction impact issues.
Roots of mature trees extend far beyond the extent of the branch tips (drip line). With adequate soil, tree roots may extend as far as 2 1/2 times the diameter of the drip line. The majority of nutrient absorbing roots exist in the upper 12 to 16 inches of soil.
During construction, tree conservation efforts require that a large portion of the tree's root system, the critical root zone (CRZ), be protected for all trees to survive. Consider removing trees that have sustained CRZ loss in excess of 30%. Tree species, health, structure, soil type, vegetation competition, proximity to structures, future planned impacts, and planned maintenance all contribute to the determination of which trees should be removed and how remaining trees can be protected.
Trees may not die immediately, but could decline over several years. With this delay in symptom development, you may not associate the loss of the tree with construction.
The Sustainable Community Forestry Staff can provide assistance by identifying trees that should remain on construction sites, offering technical assistance with tree protection methods, and referring developers to educational programs offered in Georgia.
How to Conserve Natural Resources on Construction Sites (publication)