Agenda Package - City of Vernon

American Forests: Setting Urban Tree Canopy Goals
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While each of these three surveys brought to the public's attention the alarming decline of
our nation's public trees, none of them was able to quantify the extent of a city's street tree
population at that time. Even more enlightening of these early surveys, was the inability to
quantify a community's entire urban forest population. Since only about 10% of an urban
forest is composed of street trees, we were missìng most of the story.
Today, thanks to researchers and Geographic Information Systems computer technology, we
know so much more aboutthe extent, composition, ecological and economic benefits of the
urban forest. In fact, many people now broaden the term, urban forests to urban
ecosystems recognizing the complex ecological interactions between trees and other
landcover, soils, air, water, and people.
American Forests has conducted more than 40 Urban Ecosystem Analyses in regions around
the country. Reports can be viewed at:
http=/ /www.americanforests.orglresources/urbanforests/analysis.php Satellite
and aerial imagery not only allow us to accurate[y quantify the extent of the forest and other
landcovers, but by comparing recent with historic imagery, we can also see how urban
landcover has changed over time. Based on current landcover pércentages in urban areas
across the country and in our judgment, reasonable increases, American Forests has
developed suggested tree canopy guidelines as a stafting point for communities to set their
own goals. While the goals listed below provide genera! guidelines, each community
must measure their current canopy cover and then develop tree cover targets
based on their unique mix of climate, geography, land cover, and tand use
patterns.
Why Set Tree Canopy Goals?
Tree cover in urban areas east of the Mississippi has declined by about 3070 over the last 20
years while the foot print of the urban areas has increased by 21o/o. With this decline in tree
cover/ significant air and water management costs have increased.
Tree cover is directly related to environmental quality. Maintaining a robust enough tree
cover to function as green infrastructure reduces the need and expense of buifding
infrastructure to manage air and water resources. Local agencies can use CITYgreen
software to calculate the environmental and economic values of the ecosystem services that
trees provide. American Forests' intent is to help communities calculate the value of their
trees so that city leaders can make better decisions about integrating "green" into their
urban infrastructure.
For metropolitan areas east of the Mississippi and in the Pacific Northwest:
Average tree cover counting all zones
Suburban residential zones
Urban residential zones
Central business districts
40o/o
50o/o
25o/o
L5o/o
For metropolitan areas in the Southwest and dry West:
Average tree cover counting all zones
Suburban residential zones
Urban residential zones
Central business districts
25o/o
35o/o
18%
9o/o
http://www.americanforests.org/resources/urbanforests/treedeficit.php
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