Using baseline information developed for urban foresters to estimate the value of urban tree canopies, Casey Trees and Davey Tree Expert Co. developed a tool to measure the benefit of trees that might be of interest to the home gardener: the Tree Benefit Calculator.
According to the www.treebenefits.com website, “The Tree Benefit Calculator allows anyone to make a simple estimation of the benefits individual street-side trees provide. This tool is based on i-Tree’s street tree assessment tool called STREETS. With inputs of location, species and tree size, users will get an understanding of the environmental and economic value trees provide on an annual basis.
The Tree Benefit Calculator is intended to be simple and accessible. As such, this tool should be considered a starting point for understanding trees’ value in the community, rather than a scientific accounting of precise values. For more detailed information on urban and community forest assessments, visit the i-Tree website.” The calculator estimates the overall annual benefit of a tree, but also breaks it down more specifically into storm water, property value, energy, air quality, and CO2.
I used the tool to see how it would value a large (36-inch diameter) silver maple and Japanese maple with an eight-inch diameter trunk in my front yard and a 48-inch giant sequoia growing in my back yard. Here’s a side-by-side comparison:
| Silver Maple | Giant Sequoia | Japanese Maple | |
| Storm Water (gallons per year) | 3,993 | 6,023 | 507 |
| Property Value | $60 | $0 | $88 |
| Energy (kilowatt hours conserved) | 152 kWh | 136 kWh | 22 kWh |
| CO2 (atmospheric carbon reduction) | 974 lbs | 172 lbs | 183 lbs |
| Overall | $195 | $185 | $106 |
Calculate the annual value of the trees in your garden. The results just might provide a pleasant surprise!