Urban forestry describes the installation and management of “street trees” in urban areas, an increasingly popular program across many U.S. cities.

As populations grow, the densification of urban areas is inevitable. Urban forests are a way to help support surrounding ecosystems while also minimizing the impact of expanding urban centers. 

Snoqualmie’s Urban Forestry Program consists of more than 6,000 street trees lining the sidewalks of Snoqualmie Ridge, or about one tree for every two people. In Seattle, approximately 130,000 street trees are planted for its population of almost 600,000 residents, which equates to one tree for every four people.

Benefits of Urban Forestry Programs

Urban forestry programs across the nation provide cities with a number of benefits including:

• Reduction of temperatures by shading streets and buildings
• Reduction of heating and cooling costs for surrounding buildings
• Reduction of the level of pollutants released during high summer temperatures
• Absorption of  “greenhouse” gases
• Release of chemicals that support ozone formation
• Providing wind barriers
• Reduction of water runoff and, hence, reduction of the chance of flooding

Trees not only help make our cities more attractive, but they also provide shade and improve air quality. Increasing tree canopy cover in urban areas absorbs radiation from the sun, decreasing the maximum midday temperatures. By lowering air temperatures, trees can filter out existing harmful particulates from the air, slow down the formation of additional harmful chemicals in the air and, in the warmer seasons, positively contribute to ozone formation.

A mature street tree can remove 50 pounds of harmful air pollutants in a single year, which means the street trees in Snoqualmie have the potential to remove 300,000 pounds of harmful particulates annually. In addition to these benefits, trees also help reduce levels of carbon dioxide in the atmosphere. Research done in 1993 estimated that street trees account for between 350 and 750 million metric tons of carbon storage across the U.S.

Trees also positively impact soils and waters, helping with local flood prevention. Soil management and stormwater detention are currently two of the leading concerns in the Pacific Northwest. Street trees are an effective means of soil management by significantly decreasing stormwater runoff and erosion. In the U.S., a modest planting of street trees in the area can reduce water runoff by as much as 12% in urban areas, saving the city an average of $0.18 per tree per year. If this holds true for Snoqualmie, the trees in the city are freeing up about $1,000 in the annual budget.

In social aspects, studies have shown that urban forests can greatly improve the life and well-being of residents in the area. Reduced stress, improved air quality, noise reduction, and improved real estate values are just a number of social benefits seen with the addition of street trees.

More Information:

Urban Forestry Programs