As cities expand, wooded lands and property with mature trees are being developed into commercial and residential sites.
Unfortunately, construction can be deadly to nearby trees. In most cases, trees don’t die immediately. Several years later, as symptom development occurs in the declining trees, most people don’t associate it with the previous construction.
However, it is possible to preserve trees on building sites if the right measures are taken. Trees and their root systems must be protected from damage during construction. Roots absorb the water and nutrients that are essential to tree health. Damage to roots can lead to the tree’s death. Compaction of the soil from equipment operation can hinder the tree’s absorption of nutrients.
The most important action is to set up sturdy construction fences around the tree. The fence should be placed at least at the drip line of the tree’s canopy. As a guideline, allow 1 foot from the trunk for each inch of the trunk diameter. Even with this method, 50 percent or more of the roots will be impacted by construction.
No vehicles, building materials, waste or soil should be allowed within the fenced area. No digging, trenching or soil disturbance should be performed in that space.
If construction equipment is allowed to operate close to the fencing, root pruning should be performed. A 4- to 5-inch-deep trench should be dug on the outside of the tree protection zone with an air spade, and then cut the roots cleanly with a saw.
This root-pruning technique will limit extensive damage to the roots.
The next step that will help the survival of a protected tree is irrigation during the construction phase. Stressed trees need plenty of water throughout the process. This means watering each tree about two to three times per week to a soil depth of 4 to 6 inches.
Additionally, an application of 3 inches of organic mulch within the tree protection zone would help maintain soil moisture.
But do not place mulch against tree trunks because it could cause fungus growth to the trunk. If roots are not pruned at the edge of the protection zone, mulch should be placed over any roots that could possibly be driven over to reduce compaction.
Following construction, the fencing can be removed, but irrigation needs to continue. However, the frequency should be reduced while the duration needs to be increased, to ensure that the tree receives enough water to maintain moisture in the top 12-18 inches of soil for the next year.
Simply keeping a tree on site does not mean it will survive the construction process. If measures to protect the tree cannot be taken, the most practical approach is to remove the tree before construction.
But, for some of the historical mature trees it is probably worth the effort to preserve some horticultural heritage.
Sheila Dunning is an agent at the University of Florida's Institute of Food and Agricultural Sciences Extension office in Crestview.
This article originally appeared on Crestview News Bulletin: DUNNING: With construction, leaving a tree doesn't ensure its survival