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Environmental, Campaign & Website News > New Study Shows Trees Save Portland Region Millions

New Study Shows Trees Save Portland Region Millions

Date : 24th Oct 2001, Source : Newsgroup

From American Forests

Monday, October 22, 2001

NEWS Contact: Stevin Westcott, 202-955-4500, ext. 234


New Study Shows Trees Save Portland Region Millions

Satellite Analysis Also Shows Dramatic Tree Loss Over 28-Year Period

PORTLAND, OR (October 18, 2001) - At a news conference today in Portland, Oregon, AMERICAN FORESTS ( released a new study showing how the tree canopy of the Willamette/Lower Columbia Region provides hundreds of millions of dollars in environmental and economic benefits such as reducing stormwater runoff, energy usage, and air pollution. The report also shows the area’s tree cover declined by 22% over the past 28 years, costing communities billions of dollars in lost benefits.

The following officials participated in the news conference: Portland Parks Commissioner Jim Francesconi; Brian McNerney, Portland’s City Forester; Gary Moll, Vice President of AMERICAN FORESTS; and Nancy Graybeal, Deputy Regional Forester of the Pacific NW Region, USDA Forest Service. The study was conducted with support from the USDA Forest Service, Washington State Department of Natural Resources, the Oregon Department of Forestry, and officials from the nine cities included in the study as well as Clark County, WA. The following cities in Oregon participated in the study: Albany; Beaverton; Corvallis; Eugene; Portland; Salem; Tualatin; Wilsonville; and Vancouver, Washington.

In the report, called the Regional Ecosystem Analysis (REA) for the Willamette/Lower Columbia Region of Northwestern Oregon and Southwestern Washington State, AMERICAN FORESTS analysts used satellite imagery to document changes in the study area’s tree canopy (a 7-million acre area) between 1972 and 2000. Our analysts found the total average tree cover for the region is 24%--down from 46% in 1972, said Gary Moll of AMERICAN FORESTS, the nation’s oldest nonprofit conservation organization. Despite good faith efforts to manage development, tree-canopy loss is a trend that is occurring in areas across the United States. As populations grow, so do the pressures on natural resources and the number of benefits that are lost.

AMERICAN FORESTS analyzed 63 specific sites, representing a cross-section of land uses such as residential and commercial/industrial by using aerial photography and computer software developed by AMERICAN FORESTS, CITYgreen®. CITYgreen allows users to calculate the benefits trees provide in dollar values. Analysts found the region’s trees are removing 178 million pounds of pollutants annually, a savings valued at $419 million. Sulfur dioxide, carbon monoxide, nitrogen dioxide, ozone, and particulate matter are among the pollutants trees absorb.

This same tree cover is saving communities an estimated $20.2 billion in stormwater management costs (the amount it would cost to build a facility to handle that same quantity of stormwater runoff). Besides reducing the need for stormwater facilities, trees act as filters that help purify water. Water quality is of particular importance in the Pacific Northwest because many communities are under federal mandate to improve aquatic habitats for threatened and endangered salmon species.

Trees (or green infrastructure) help shade and cool residential homes during hot summer months, thereby reducing the amount of electricity needed to run air conditioners. AMERICAN FORESTS’ REA finds trees provide an estimated $1.86 million in annual energy savings for communities in the area. Reducing energy use also reduces the amount of carbon emissions by utility companies. Direct tree shading prevents approximately 140,000 tons of carbon from being emitted into the atmosphere annually.

One of the most interesting findings of the report is that the Portland region is, for the most part, either densely forested (21%) or open/agriculture land (75%). There are few areas with moderate tree cover (4%). Areas with heavy tree cover declined by 56%, whereas areas with light tree canopy grew by 51% during the study period.

Losing tree cover reduces environmental quality and the overall health of a community. If the tree canopy of 1972 had been retained, an estimated 58 million tons of carbon would not have entered the atmosphere. The lost tree cover increased stormwater runoff that costs an estimated $2.4 billion to manage and would have removed 138 million pounds of pollutants annually, valued at $322 million per year.

AMERICAN FORESTS recommends that most regions maintain a 40% average tree cover. If the Portland region met that recommendation, trees would provide about $1.03 billion worth in pollution removal and 146 million tons of carbon would be stored a year.
Lastly, the Regional Ecosystem Analysis recommends specific actions that local decision makers can take to increase the tree canopy of the Willamette/Lower Columbia Region. They include: utilizing CITYgreen and other tools in this study to incorporate a green layer in land development decision-making; encouraging the use of increased tree cover as one strategy for meeting air pollution and stormwater management needs; and continuing to work towards increasing and conserving tree canopy in metropolitan areas.

Development is causing many of our cities to become cities of sidewalks, roads, and buildings (gray infrastructure) by removing trees (green infrastructure). This tree-loss trend has adverse environmental and financial effects and degrades the overall health and quality of urban, suburban, and rural environments. By conducting Regional Ecosystem Analyses in cities across the United States, AMERICAN FORESTS estimates 634 million trees are needed to bring America’s urban areas up to 40% average tree canopy. In recent weeks the organization unveiled a new national campaign called Gray to Green: Reversing the National Urban Tree Deficit that encourages people everywhere to plant trees to help improve the quality of our cities. AMERICAN FORESTS has the ability to conduct a Regional Ecosystem Analysis for any city or region in the continental United States.

Founded in 1875, AMERICAN FORESTS is the oldest national nonprofit citizen conservation organization. AMERICAN FORESTS is a world leader in planting trees for environmental restoration, a pioneer in the science and practice of urban forestry, and a primary communicator of the benefits of trees and forests. AMERICAN FORESTS is on the World Wide Web at

For more information, contact:

Stevin Westcott
Communications Director
American Forests
202-955-4500 ext. 234
Web site:

Document last updated on Wednesday 01 August 2018

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