The trees planted along city streets do a whole lot more than just look pretty, and the work they do now has a monetary value.
Researchers at the University of California, Davis and the USDA Forest Service analyzed data collected on 929,823 trees from 50 cities across the state. They looked at everything from carbon storage to rainfall retention in an effort to put a monetary value on the ecological services that city trees provide residents.
So what exactly is the value of the services provided to us by California's 9.1 million city trees? About $1 billion, or a value of about $110.63 per tree. In other words, city trees provide a wonderful return on investment. The researchers report:
The state’s street trees remove 567,748 t CO2 (92,253 t se) annually, equivalent to taking 120,000 cars off the road ... Given an average annual per tree management cost of $19.00, $5.82 in benefit is returned for every $1 spent. Management implications could include establishing an aggressive program to plant the 16 million vacant sites and replace removed trees, while restricting planting of overabundant species.
The numbers underscore the importance of planting trees, especially of planting diverse species of trees, and prove to city managers that it is worth the expense and effort of planting and maintenance when it comes to making a city a healthier, more beautiful place. And it also illustrates why organizations like Friends of the Urban Forest are so important to cities.