About Trees: Protect prized trees when adding pool

My daughter, son-in-law and their children are excited about the construction of a pool in their backyard. It's finally happening, after much deliberation and discussion.

>One of the big points of discussion has been about the impact such a project would have on a large, mature and beautiful water oak in their backyard.

Being the tree guy they know best, I was invited into the discussion about how to accomplish the goal of a pool without incurring damage to this central and irreplaceable tree. It is the same question I have gotten many times over the years from clients and property owners.

No two situations or properties are the same. Lot sizes and dimensions always vary.

Then there's the issue of the species and size/age of the tree or trees. Some types tolerate stress and mechanical damage far better than others.

And, generally, larger trees require a much more protected and undisturbed root-soil area before and during construction in order to reasonably expect a good outcome three years later.

The awareness by the contractor and his crew regarding the importance of establishing and maintaining a Tree Protection Zone is critical. This is the area under or near the tree where additional compaction or disturbance of the soil and roots could damage the tree.

The perennial question always seems to be: "How close can we get and get away with it?"

The general rule is somewhere around the drip line, which is the radial distance from the trunk outward to the ends of the limbs. Of course, tree roots often extend well beyond the drip line, but if no other damage has recently occurred or is anticipated, this may be a reasonable point to work with. Can you get closer? Well, yes, sometimes.

If time is available before the beginning of digging and construction, it can often be helpful to prep the patient for the coming disturbance by a careful partial pruning of the roots the season before. Root pruning can serve one or more purposes.

First, surgically severing approximately 50 percent of the tree roots extending across the protection zone and into the construction area will permit a head start on root regrowth.

Secondly, and especially when digging has to be closer in toward the trunk, root pruning can prevent the ripping and tearing of larger roots by a backhoe.

A continuous or interrupted trench to a depth of 15 inches is usually sufficient in Memphis' clay soil.

There are other factors as well. An assessment of tree health is important. What is the season or time of year for the beginning of work? How will adequate irrigation be accomplished during the stress period?

So with a lot of planning, some adjustments and some prudent preparation, we think we will have a success at my daughter's house.
