Avoid Plant Injury During Construction

Whether you're planning an addition or preparing to build your dream home on the "perfect" lot, you should know that construction can kill trees. The good news is that construction doesn't have to have such a devastating effect if you are willing to plan and be realistic.

By realistic, I mean that you have to face the fact that with virtually any type of construction project, some closed in trees will have to be removed. Once you've accepted this unpleasant fact, you can move on to deciding which trees to save and how they should be protected.

Construction generally causes two types of damage to existing trees. Type one is the most obvious-heavy equipment can damage bark, break branches, roll over roots and compact soil. The second type of damage is a little subtler.

When any area is developed, there are changes in the water table. Streets are dropped below grade to aid run off. Sewers are dug even deeper, further dropping the water table. Frequently, the soil dug up from many feet below ground level is placed over existing topsoil, altering the trees' ability to get air, water, and nutrients and give off carbon dioxide.

Trees adjacent to construction can be damaged just by the pounding of the equipment, wheels, piles of lumber, paint solvents, etc. In addition, when trees are cut down to make way for streets, many of the trees left standing are buffeted by the wind, deprived of the protection fo the other trees. In addition, the remaining trees no longer are shaded by the other trees that had protected them from summer's heat, nor do they benefit from the extra falling leaves that had protected their roots from freezing and drying in the winter.

Damage doesn't stop with the completion of the street, however. Construction crews and subcontractors clean their equipment and burn their trash in what will soon be your yard. All this debris contributes to the subtle damage that can kill a tree over time.

But before you begin thinking your trees are doomed, let me tell you how to save them. First, realize you can't save them all. Get a professional horticulturist or arborist to advise you which trees are worth saving. Then, work with your builder, letting him know which trees you expect to have living for the next century or so. Next, fence in those trees. Snow fence works well, as does chicken wire. Use heavy corner posts with yellow paint as a marker. Explain to the builder that you don't want any burning or cleaning of equipment near the trees. Finally, assign a value to each tree and sign an agreement with your builder that the designated trees are to be protected. At the closing, the builder will owe you the value of any tree that is obviously damaged or destroyed. Be sure to check each tree carefully since it can take three to five years for a mistreated tree to succumb to damage.

There are other steps to consider, as well. If the lot must be graded and the grading will cover a portion of the tree trunk, you should keep all personnel and equipment away from the trunk and off roots, clear to the drip line of the tree. Another option is to build an aeration system for the tree.

This involves building a well around the tree and placing perforated drain tile on the existing grade level exiting through the wall. A return pipe is also put in place from the root zone to the surface on the far end to allow respiration. A six-inch deep layer of gravel over the tile and roots out to the drip line is also a good idea.

One last consideration is to simply remove the trees that seem imperiled and plant new ones where you want/need them when construction is over. I recommend that you consider this option before spending a great deal extra for a wooded lot that eventually can't be saved. Be sure to call for a consult before construction or even while considering which lot to buy.