Marianne Ophardt

Garden Tips: From millions to billions: the value of a city’s trees

Trees provide a great deal of value to communities — beauty, shade, quality of life. Computer software called i-Tree allows cities to now place a monetary value on their trees.
Trees provide a great deal of value to communities — beauty, shade, quality of life. Computer software called i-Tree allows cities to now place a monetary value on their trees.

If you have trees in your yard, you no doubt know the benefits and drawbacks of trees. On the benefit side, trees provide cooling shade. When strategically placed they can significantly reduce heating and cooling costs. Trees protect the environment, reduce stress, improve our overall health and provide us with beauty. It is also well documented that healthy, mature trees in a nicely landscaped yard can increase a home’s property value by as much as 20 percent.

Disadvantages of trees include the time and expense involved in raking leaves, properly pruning trees to maintain their health and beauty, and mitigating problems caused by the surface roots of large shade trees.

While I think the benefits and beauty of trees far outweigh their drawbacks, more objective people may not perceive their intrinsic value. They want to know the measurable dollar value of trees. After all, every year cities spend taxpayer dollars to plant and maintain trees in parks and along city streets. Is this investment worth it? Urban foresters, horticulturists, environmentalists and economists have been endeavoring for over 30 years to answer that question with research and hard data.

For example, David Nowack, a U. S. Forest Service scientist, has spent his career researching city trees and developing ways to assess their value and develop tools to help cities better plan, manage and assess their urban forests. One of the many results of his research has been i-Tree, a computer software suite that provides cities and towns with different analysis tools to help monetize the value of their urban forests and aid them in the management of their trees.

This software helps city staff establish a tree inventory. Tree inventories enable staff to track tree health and schedule needed maintenance tasks, including pruning and pest management. They can use the inventories to guide them in the selection of new trees to ensure a diversity of species. Inventories are important tools in documenting the dollar value that urban forests provide to cities with their contributions in improving air quality, managing stormwater and saving energy.

Nowack led the use of i-Tree software to analyze the value of city trees in Austin, Texas. City officials found that Austin’s trees represent a physical asset of $16 billion (for roughly 33.8 million trees). Those trees save the city $19 million every year in reduced building energy use. They also quantified the city’s savings of $5 million in reduced carbon emissions and a reduction in air pollutants worth $3 million. An analysis of the urban forest in Portland revealed that the city’s street trees have a capital value of $1.1 billion, pointing out why it is well worth spending $4.6 million every year to maintain them.

However, we are not in Austin or Portland. Our local cities have also been using i-Tree or similar software programs to establish tree inventories, manage their street and park trees, plan for the future, and document the value of our local cities’ trees. In 2000, Walla Walla, a city that “takes great pride in their community trees” and has a tree as part of their city logo, documented the value of their city trees at $13.3 million. It is currently working on updating that value. The city of Richland’s software indicates that the value of its trees is $1.7 million based solely on total appraised value as determined by the trees’ species, size, location and condition.

Trees are an investment in our cities’ present and future. Congratulations to all of our local cities for recognizing the value of urban forests and wisely utilizing tax dollars to protect them.

ARBOR DAY

Cities around the country honor the value of city trees with Arbor Day celebrations and tree plantings during the month of April. Some local cities have already held their celebrations, but those who have not invite you to join them in observing Arbor Day. Upcoming Arbor Day events:

City of Pasco, 9:30 a.m. April 18, with the Boys & Girls Club, at 18th and Sylvester near the Edgar Brown Stadium entrance

City of Walla Walla, 10:00 a.m. April 25, at Berney Elementary, 1718 Pleasant St.

City of Richland, 2:30 p.m. April 27, at the new city hall, Jadwin and Swift

Marianne C. Ophardt is a retired horticulturist for Washington State University Benton County Extension.

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