The net economic contribution of trees is coming to be better quantified
and appreciated with the use of computer-assisted methodologies.
It is now possible to calculate an approximate economic impact of
tree resources on a community-wide metropolitan and even global
Recently, researchers from around the globe developed an estimate
of the economic contribution of the planet’s natural systems.
This particular study placed the net economic worth of the environmental
services provided by the world’s forest biome at $4.7 trillion
A comprehensive study at the metropolitan level modeled the projected
costs and benefits of planting and maintaining 95,000 trees around
the Chicago area over a 30-year period. The researchers projected
that the value of the air pollution attenuation, energy-saving,
hydrologic and other benefits provided by trees would exceed the
costs to plant and maintain them by an average of nearly three-to-one.
It was estimated that investments in trees yield an average net
present value (benefits less costs) of $402 per tree planted and
to have an average payback period of between 8 and 19 years (depending
on location, species and discount-rate assumption).
However, planned urban forests are not without costs. Planting
and maintaining trees requires an investment of not only monetary
resources but human resources as well. It should be noted that without
proper planning and maintenance, trees can have negative impacts:
uprooted sidewalks, leaf collection in such areas as streets and
culverts, disrupted utilities and tree damage. These effects all
incur costs to the community and private landowners. However, the
costs of planting new trees and maintaining existing trees are tangible
and the benefits of trees are often diffused and enjoyed as “public
goods” by society at large.
Click here for a worksheet
authored by Brian Kane of the University of Massachusetts and Jeff
Kirwan of Virginia Tech. This worksheet is meant for demonstration