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Quantifying Urban Forest Structure, Function, and Value

This paper reviews research concerning urban forest structure, function, and value, with emphasis on results from the Chicago Urban Forest Climate Project. In 1991, the $59 million in benefits from its trees in energy savings, air-pollution mitigation, avoided runoff and other benefits far outweighed the $21 million in costs of planting and maintenance. It takes between 9 and 18 years to pay back planting and maintenance costs.
  • During 1991, trees in the Chicago region removed an estimated 5575 metric tons of air pollutants, providing air cleansing worth $9.2 million.
  • In Chicago, the $59 million in benefits from its trees in energy savings, air-pollution mitigation, avoided runoff and other benefits far outweigh the $21 million in costs of planting and maintenance (assuming a 30 year time period, 7% discount and 95,000 trees planted).
  • Trees increase shade and lower summertime air temperatures. Mature trees reduce neighborhood wind speeds. So, increasing tree cover by 10%, or about 3 trees per building lot, will create an annual estimated savings of $50-$90 per lot.
  • The length of time needed to pay back planting and maintenance costs varies with the species planted, planting location, and level of care that trees received. In Chicago, this period ranges from 9 to 18 years.