morton tree talk » More on the Value of Trees

Science and factoids about the Arboretum

More on the Value of Trees

Planting trees is a great investment for the future. They grow more beautiful and valuable over time. Trees bring a great return on investment. The U.S. Forest Service has determined the average community’s tree benefit-cost ratio.

Typical Benefits		Typical Costs
Energy	$43,000	Planting	$21,000
CO2	9,000	Pruning	37,000
Air Quality	9,000	Removal/disposal	8,000
Runoff	46,000	Irrigation	6,000
Aesthetic	118,000	Sidewalk repair	1,000
		Litter	3,000
		Admin	1,000
Total	$225,000	Total	$83,000

In 40 years, the average tree returns $2.70 in benefits for every $1 of community investment. And trees improve the quality of the urban environment.

The environmental benefits depend on healthy trees:

Large healthy trees remove 60-70 times more pollution than small trees.

Large healthy trees sequester up to 1,000 more CO₂than small trees.

Trees require quality care to remain healthy.

Forestry program needs continued advocacy and support.

The Chicago Urban Forest Climate Project (U.S. Forest Service 1991) was a three-year study of the environmental impacts of the urban forest of the Chicago region. It found that the estimated 50.8 million trees in Cook and DuPage counties combined contributed the following benefits:

1. Trees store an estimated 6.1 million tons of carbon. Further studies led to the estimate that 100 mature trees remove five tons of CO₂from the atmosphere per year, which is equivalent to emissions from one car in a year.

2. The trees in our region remove these pollutants from our air:

17 tons of CO

93 tons of SO₂

98 tons of NO₂

210 tons of O₃

224 tons of particulate matter <10 microns (PM 10)

3. The estimated value of this pollution removal in 1991 was $9.2 million.

4. Localized air quality improvement could be 5-10% with high tree cover.

5. The U.S. Forest Service estimates 100 trees remove 1,000 lbs. of pollutants per year, worth about $4,500 in emission credits (in the Central Valley of California).

6. Optimally placed landscape shade trees could reduce local cooling energy use for 1.3%, cooling energy use by 7%, and peak cooling energy use by 6%.

7. Increasing the region’s tree canopy by 10% could reduce total heating and cooling energy by 5-10%.

8. Reduced air-conditioning demands avoids CO₂ generated from “peak” energy production, which is usually coal generated in Illinois.

9. The U.S. Forest Service estimates 100 mature trees intercept about 250,000 gallons of rainfall per year in their crowns, reducing runoff of polluted stormwater.

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