Root zones are a critical area of concern with the preservation of trees on a construction site. Since roots are essential to both the stability and the health of a tree, it’s important to avoid damaging to them.
New construction threatens existing root zones in several ways. Physical damage from construction equipment is an obvious threat. Additionally, soil problems can develop from either the removal of topsoil or its contamination from construction products. Finally, changes in grade may influence the movement of water by either channeling water to or away from the roots, changing the whole dynamics of water availability.
Tree protection fencing with clear signage can help minimize problems caused by construction equipment. Root pruning can be done along the limits of clearing to make clean cuts rather than letting bulldozers rip and tear at the roots. If some roots will be under a pathway of construction equipment, a temporary layer of wood chip mulch up to a foot thick can help disperse the heavy weight.
Silt fencing should be installed around the limits of clearing to avoid the movement of soil into the preservation area. Also, dirt should never be piled over the root zone.
Water flow is an often overlooked consequence of new construction. Grade changes can have a dramatic impact on the quantity of water available to trees. Too little and the roots can’t absorb enough to sustain cell viability. Too much and the ground becomes saturated, crowding out oxygen from open pore space, essentially suffocating the tree.
The goal of the arborist working with a contractor to protect the trees on site is to minimize the impact of the construction process on the tree. The earlier he is called into the project, the more successful the outcome.Paul Martin