Determining a tree's value
September 7, 2009 · 2:14 PM
By Dennis Tompkins
For The Courier-Herald
Trees have value. A large tree in a nice landscape may be worth thousands of dollars. This does not mean a homeowner could sell a tree for these prices, but there are situations where estimated values come into play.
Certified arborists are often asked to value trees that are involved in disputes, have been damaged by accidents or were intentionally cut or mutilated.
Two methods are used in valuing trees in a landscape situation: a replacement value or a “trunk formula” method. Timber values may be used in a true forest environment.
If a landscape tree is of replaceable size, a value can be estimated by nurseries that specialize in obtaining and planting appropriate sized trees. Conifers more than 25 feet tall have been successfully transplanted.
Trunk Formula Method:
When trees are too large to be replaced, arborists will use a “trunk formula” method whereby a tree’s value is based on its diameter, species, condition and location within a landscape.
To visualize the process, assume a tree in your yard is equivalent to a used car that is compared to a brand new car at the factory or a perfect tree in a highly maintained landscape. Such a “used tree” must be discounted to a value as it exists in its current environment.
The first step is to determine a “basic value” from a table of trunk areas based upon a tree’s diameter measured at 4.5 feet above the ground. This value is then adjusted according to tree species.
For example, northwest arborists have determined that a Douglas fir is worth 75 percent of the basic value compared to 40 percent for a black cottonwood. Species ratings are based upon a tree’s hardiness, ornamental features, structural stability, maintenance requirements and other factors.
A condition rating or discount is based upon close inspection of a tree’s roots, trunk, branches and foliage. A well maintained, healthy tree may be rated at 70 to 90 percent. One that has a multitude of problems may be rated at 40 percent or less.
The location adjustment considers the general site, placement and contribution of a tree to a landscape. A tree that is a focal point in a well-maintained neighborhood is worth more than a tree located in a more natural environment. A single specimen has a higher value than if located among a group of trees.
Oftentimes the process is initiated by an attorney who calls and states that a client’s tree was cut or mutilated by a neighbor, construction crew or a tree service. The damage may involve a certain portion or an entire tree. The final value estimate will be based upon the percentage of a tree that was damaged.
A Douglas fir with a diameter of 18 inches that is in good condition, is located in a nice neighborhood and is important to the landscape may be valued at $5,000 or more. A 24-inch tree may increase to more than $9,000.
A low-growing but small-diameter Japanese lace leaf maple that is several years old, has many intricate twisted branches and is a prominent feature of a landscape may also be worth several thousand dollars.
There have been well publicized incidences where the removal of trees on public property in Seattle and the mutilation of dozens of trees in Lacey by a tree service have resulted in settlements of several thousand dollars by the responsible parties.
Should a landscape tree be cut?
Now, understanding that trees do have value, a homeowner may view a questionable tree from a different perspective.
Obviously, the answer depends upon several factors other than its potential landscape value. Safety is a prime concern. Any tree that has a potential manmade target and is in good condition will generally be safe for several years.
A tree that has some defect such as multiple tops, a crook in the trunk or visible decay ideally should be inspected by a professional. Certified arborists trained in hazard tree assessments are excellent sources for such evaluations.
Do note that it is important that a hazard tree assessment not be unduly influenced by someone who also is interested in selling tree removal services.
Dennis Tompkins is a certified arborist, certified hazard tree assessor and Master Gardener from the Bonney Lake-Sumner area. He provides small tree pruning, pest diagnosis, hazard tree evaluations, tree appraisals and other services for homeowners and businesses. Contact him at 253 863-7469 or email at firstname.lastname@example.org. Website: evergreenarborist.com.