Davey Tree Expert Company has a
calculator on their website where individuals can calculate the annual dollar value of all the benefits the trees on their property provide -- to them and to the community at large!
For example, the 39 inch bur oak provides nearly $400 worth of benefits annually, including more than $195 in stormwater management by eliminating over 7,000 gallons of stormwater runoff every year! Without that tree, all of that rain water would flow rapidly to the street, helping to overwhelm the stormsewers.
Now, when I add up the stormwater caught by all of my trees: three bur oaks, one white oak, a cottonwood, two maples, two pears, and two honey locusts, the stormwater savings alone of these trees amounts to nearly $2000 a year, or 65,000 gallons of stormwater that is intercepted rather than running off into the stormsewers!
- Intercepting and holding rain on leaves, branches and bark
- Increasing infiltration and storage of rainwater through the tree's root system
- Reducing soil erosion by slowing rainfall before it strikes the soil
And you know what, the trees cost us virtually nothing. Sure, we rake the leaves in the fall (which is good exercise, by the way), and pick up branches after a windstorm, but the annual cost is minimal.
This kind of information makes me think that more communities could invest in promoting city trees as part of their stormwater management program rather than (or in addition to) expanding their stormsewer systems. I would guess that it is much less expensive to manage 7,000 gallons of water with a mature tree than by building more stormsewers.
According to
American Forests: As communities grow, trees are removed to make way for impervious surfaces such as parking lots, roads and buildings. Our studies show that impervious surfaces have increased by 20% over the past 2 decades in urban areas. Constructed stormwater facilities are created to compensate for the tree loss. These facilities are expensive to build and maintain. The cost has been calculated to be in excess of $100 billion nationally.