Homebuilding, 17-year Cicadas, and Tree Preservation

The arrival of 17-year cicadas in the Washington DC area always reminds me how important it is to consider the natural world when building or renovating a house. I have noted greater cicada density in some parts of metro Washington than in others.

What accounts for the difference? Often, you can find more cicadas in areas where there has been little home construction in the past 17 years. When the soil has been disturbed and trees have been removed, cicadas are likely to have been removed as well. Older homes and older neighborhoods are more likely to have lots of cicadas. The bugs may be a bit unnerving looking, but their presence is a sign that nature is in balance with human inhabitants.

Why Preserve Trees?

I like to remind my clients that trees are useful for other reasons than supplying fat and noisy insects every 17 years. Almost any remodeling, construction, or landscaping project looks better with a few trees around it. Mature trees provide a wide variety of other benefits:

• They improve the quality of water, soil, and air and remove pollutants from the air.
• Shade trees help lower home temperatures during hot weather.
• Trees have a positive effect on the image and attractiveness of a property.
• Properties with mature trees sell more quickly and at higher prices, increasing their worth up to 12%.

Home Construction and Tree Preservation

However, home construction and renovation can be hard on trees. Soil compaction from heavy machines or construction material storage decreases soil permeability, lowers oxygen levels, and increases carbon dioxide. Surface grading removes vegetation and topsoil that contain many of the shallow roots a tree needs to absorb nutrients. If tree bark is damaged or removed by equipment, the tree is highly susceptible to root pathogens and fungi. Roots can be cut during the digging process, endangering the tree.

All of these things cause stress, and stressed trees are more susceptible to insects such as bark beetles and borers. No matter how much care you take, some root loss is inevitable. Trees’ ability to tolerate root loss and recover from changes in their environment varies considerably depending on species and age.

Choosing Trees to Preserve

I recommend to my clients that they have the existing trees evaluated by a licensed arborist prior to the start of construction. The arborist will evaluate your trees based on size, species, vigor, cost of preservation, and cost of removal. That helps homeowners determine if preservation is worthwhile and feasible. Certain species are better candidates for preservation than others.

For example, sycamores and white oaks are stronger and live longer than silver maples or cottonwoods; so they are more suitable to preserve. Trees that are sickly, short-lived, or susceptible to pests may not be worth preserving.

The arborist can prepare a tree inventory that provides information about protective measures so contractors and property owners can make informed decisions about which trees to protect.

How to Preserve Trees

Once you have chosen trees for preservation, you need to prepare a plan with specific tree preservation methods. Tree protection guidelines may include: prominently marked protected areas, barricades around preserved trees, preventing traffic or parking in restricted areas, and prohibiting material storage, grading, and dumping chemicals in protected areas. Arborists may also recommend irrigation, fertilizing, pest and disease management, cabling or bracing, or pruning. While some of these measures may sound expensive, remember that preventing damage is less costly than correcting it.

The root zone extends horizontally from the tree for a distance at least equal to the tree’s height. In order to maintain a healthy tree, you want to preserve at least 50 percent of the root system. You can do so by providing a tree protection zone, a fenced area around a tree that may be covered with wood chips. In this zone the soil is protected from compaction, critical roots are not damaged by pruning, trenching, or excessive grade changes, trunk, and branches are protected, and the tree will receive adequate supplies of soil nutrients, air, and water.

When establishing a tree protection zone, construction needs must be considered alongside the needs of the trees. When feasible, the zone should be outside the tree’s dripline. However, construction site space is often limited, and this isn’t always possible.

Here’s the bottom line: if you want to preserve mature trees on your property, you need to be proactive. You need to get expert help in choosing which trees to preserve and how to protect them.

Considering home remodeling in the Washington DC area? Contact Superior Construction!