Explainer

# Stopping By Woods

## Tiger Woods’ car crash caused \$200 worth of damage to a tree. How do you measure that?

Tiger Woods’ car crash last week caused \$3,200 in property damage —\$3,000 to a fire hydrant and \$200 to a neighbor’s tree, the Florida Highway Patrol announced Wednesday. How do you assess monetary damages to a tree?

It depends on its size. The simplest way to measure a small tree’s value is to calculate how much it costs to replace. That’s the price of a suitable substitute from a nearby nursery plus transport and labor costs. Dollar amounts vary depending on the species. A 3-foot Japanese Maple, for example, costs about \$200 in Illinois, whereas you can purchase a spruce for \$1.

If a tree is decades-old and massive, calculating its cost is more complicated. The most straightforward way is the “trunk formula method,” as laid out by the Council of Tree and Landscape Appraisers’ Guide for Plant Appraisal. This formula incorporates the tree’s size, species, location, and condition. You start with the tree’s species rating—a number between zero and 100 that’s based on all kinds of factors, from the tree’s rarity to its gender to the quality of its wood. A female Ginkgo tree, for example, is cheaper than a male, because its seeds smell like vomit. (The ratings are set by regional plant-appraisal committees made up of tree growers, consulting arborists, and other specialists.) You then multiply the species rating by the tree’s cost per square inch, which varies by region—for instance, urban trees cost more per square inch than rural trees—and add on the cost of replacing it to get the tree’s “basic value.” Lastly, you factor in its condition and location—again, a rating between zero and 100—to get its full value.

The trunk formula method is helpful if your neighbor cuts down your entire tree, thinking it was on his property. But it’s less useful if someone—the pro golfer next door, say—merely scratches up the tree. In that case, the damages assessed are just the cost of repair. You can’t “fix” a tree, exactly. But a landscaper can clean it up to make it look more aesthetically pleasing. (See a picture of the damage here.)

Another appraisal method is to figure out the value a tree adds to a piece of property. To calculate that, an appraiser compares nearby properties that have trees to similar properties without them. The price difference is the value of the trees. Aesthetics and rarity matter, too. If a house looks out onto a single, gorgeous Maplewood, that increases its value. And a single tree is worth more than one tree in a forest of thousands. Appraisers might also calculate the value of a tree as the amount of income it could generate for its owner were it converted to timber.