Build a House Without Destroying the Forest

In your mind, what is the ideal lot for a new house? Fifty years ago, most people would have replied: a piece of flat land devoid of any vegetation other than a vast green lawn. Today, though, most people would prefer a wooded lot with a bit more character: a slope, a rock face or even multiple levels. New owners want to feel like they’re surrounded by nature, even in the suburbs… and no longer feel the need to have to keep an eye on everything their neighbors do.

Unfortunately, the buyer of a “wooded lot” is often disappointed with the long-term results: after 5 to 10 years, the beautiful forest surrounding his new home is often dead or dying. What happened?

There are three main problems that cause the decline of residential woodlots: poor tree selection, lack of attention during construction and excessive interference in the forest after construction.

Pick and Choose the Trees to Maintain

Whether you like it or not, it is almost never possible to keep all the trees when building a house on a wooded lot. Not only will the trees closest to the construction site be severely damaged (broken branches, scraped trunks, root compression, etc.) by the passage of heavy machinery necessary for construction, but the very fact of installing a house in what was previously a dense forest weakens the surrounding trees.

Remember that forest trees grew up in an environment protected from the elements by their neighbors. They grow taller and thinner, with weaker trunks, than trees growing out in the open. When suddenly exposed to strong and drying winds by a large gash in the forest, not to mention the inevitable change in soil moisture levels that follow construction, they tend to either snap or to slowly die back over the years that follow construction.

To protect the woodland as you build on a private lot, it’s best to carefully choose which trees to maintain.

Since large trees are the first to suffer from disturbance, it is preferable to sacrifice them from the start if they are growing near the house (few large trees will survive if they are less than 5 feet/1.5 m from a foundation that is being installed, even when great care is taken). This is especially true if they are species that simply don’t recover well from root disturbance or branch damage, such as sugar maples (Acer saccharum), black walnuts (Juglans nigra) or white oaks (Quercus alba). Instead, in such spots, it’s best to preserve younger trees: they adapt better to change.

In areas well away from the damage of heavy machinery, it’s much easier to keep larger trees healthy… provided they’re not expected to put up with any radical changes. To ensure they don’t, consider installing a transition zone of saplings, shrubs and perennials that will act as a buffer between the newly stripped portion of the lot and the original forest.

If you have difficulty choosing the trees you should keep, consult a certified arborist. An expert will be able to tell you if there are frail, diseased or poorly placed trees that could be more easily sacrificed and also to recommend any pruning that will be needed on the remaining trees in order to reduce damage during construction. It’s much easier on a tree to have a branch carefully removed by an expert than violently ripped off by a bulldozer!

ProtectIng the Remaining Trees

Once you’ve chosen which trees you intend to keep, you have to protect them from heavy machinery. Work with your contractor to delineate a “construction zone”, an “access zone” and a “parking area” with a bright colored safety fence. In other words, give the contractor the space they need to do their work while making it perfectly clear where machinery is not allowed. Hang strands of orange safety tape from any overhanging branches both sides agree can be preserved.

Make sure too that the contractor understands that it’s also forbidden to pile soil on top of tree roots, even temporarily. As harmless as this may seem, it severely compacts the soil and also reduces air circulation to the roots. The result is often the slow decline of the impacted trees over many years.

In addition, cover the access and parking zones with a thick, coarse organic mulch: a layer of chipped branches at least 6 inches (15 cm) thick. This can make an enormous difference in avoiding soil compression, even under the weight of the heavy machinery, plus it protects trees against the slow death of their roots due to asphyxiation.

Sensible Maintenance

When construction is over, remove the protective mulch while leaving the forest humus in place as much as possible.

And don’t rush in to instill sod in the wooded sector. This a real no-no: not only do lawn grasses not grow well in the shade of trees, meaning you’re wasting your time, but covering the roots of the trees with a new layer of soil to allow for the installation of a lawn causes tremendous disturbance to their roots and will also destroy the complex web of soil microbes that allows the forest’s survival. Let the forest take care of itself as much as possible, limiting your interventions mostly to installing the transition zone between the forest and the house or lawn.

Adding a mulch-covered path or two that meanders through the forest does little harm, however, and allows you to enjoy your wooded lot. Feel free to add a few shade plants – ferns, hostas, native plants, etc. – on either side to add interest. If you do this gradually, over several years, the forest will cope perfectly with the change.

In planting a little in accessible spots and otherwise letting the forest grow on its own elsewhere, you’ll reach a balance that ensures the forest will remain healthy with little effort on your part.

Finally, don’t remove fall leaves from the forest but rather let them build up at will. They are the source of the rich humus that guarantees the woodland’s survival.

The “nearly natural” garden that results from only minimal planting and maintenance in the tree root zone will create, in the decades to come, a nice complicity between the natural forest and your beautification goals: complicity that will guarantee the short-, medium- and long-term survival of your beautiful wooded lot.