Q. How do I avoid tree damage during construction?
A. As cities and suburbs expand, wooded lands are being developed into commercial and residential sites. Homes are constructed in the midst of trees to take advantage of the aesthetic and environmental value of the wooded lots. Wooded properties can be worth as much as twenty percent more than those without trees, and people value the opportunity to live among trees.
Unfortunately, the process involved with construction can be deadly to the nearby tree. Further, unless the damage is extreme, the 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 the construction.
It is possible to preserve trees on building sites if the right measures are taken. The most important step is to hire a professional arborist during the planning stage. An arborist can help you decide which trees can be saved, and can work with the builder to protect the trees throughout each construction phase.
Q. How are trees damages during construction?
A. Physical injury to the trunk and crown – Construction equipment can injure the above-ground portion of a tree by breaking branches, tearing the bark and wounding the trunk. These injuries are permanent, and if extensive, can be fatal.
Cutting of roots – The digging and trenching that are necessary to construct a house and install underground utilities will likely sever a portion of the roots of many trees in the area. It is easy to appreciate the potential for damage if you understand where roots grow. the roots of a mature tree extend far from the trunk of the tree. In fact, roots typically will be found growing a distance of 1-3 times the height of the tree. The amount of damage a tree can suffer from root loss depends, in part, upon how close to the tree a cut is made. Severing one major root can cause the loss of 5-20 percent of the root system.
Another problem that may result from root loss due to digging and trenching is that the potential for the trees to fall over is increased. the roots play a critical role in anchoring a tree. If the major support roots are cut, one side of a tree may fall or blow over.
Soil Compaction – An ideal soil for root growth and development is about 50 percent pore space. These pores, the spaces between soil particles, are filled with water and air. The heavy equipment used in construction compacts the soil, and can dramatically reduce the amount of pore space. This not only inhibits root growth and penetration, but also decreases oxygen in the soil that is essential to the growth and function of the roots.
Smothering roots by adding soil – Most people are surprised to learn that 90 percent of the fine roots that absorb water and minerals are in the upper 6 -12 inches of soil. Roots require space, air and water. Roots will grow best where these requirements are met, which is usually very near the soil surface. Piling soil over the root system or increasing the grade will smother the roots. It only takes a few inches of added soil to kill a sensitive, mature tree.
Exposure to the elements – Trees in a forest situation grow as a community, protecting each other from the elements. The trees grow tall, with long, straight trunks and high canopies. Removal of neighboring trees, or opening and sharing canopies of trees will expose the remaining trees to sunlight and wind. The higher levels of sunlight may cause sunscald on the trunks and branches. Also, the remaining trees will be more prone to breaking from wind or ice loading.