PURPOSE OF THIS URBAN TREE CANOPY ASSESSMENT

The City of Salem is located within Marion County and Polk County in northwest Oregon. The study area for this assessment is the Salem City Limits and the Urban Growth Boundary (UGB) of Salem (excluding Keizer). The Study Area totaled nearly 61 square miles or 38,740 acres of which 37,644 are land acres. Across the City, trees along streets, in parks, yards, and natural areas constitute a valuable urban and community forest. This resource is a critical element of the region’s green infrastructure, contributing to environmental quality, public health, water supply, local economies, and aesthetics.

The primary goal of this assessment was to provide a baseline and benchmark of the City’s tree canopy, interpret the results across a range of geographic boundaries, and evaluate how the City’s canopy has changed since 2009, when the last urban tree canopy assessment was conducted. For purposes of this study, the Universal Transverse Mercator (UTM) coordinate system was used for all area (acres) calculations. Every coordinate system is an attempt to accurately represent the earth in two dimensions which causes some level of distortion in shape, size, direction, and distance. The exact area of the official UGB will differ slightly depending on which coordinate system was used. The total area of the UGB in NAD 1983 UTM Zone 10 (used in this study) is 38,740 acres compared to 38,764 using the NAD 1983 Oregon Lambert Conic Conformal coordinate system which is commonly used in other studies in the City of Salem.

URBAN TREE CANOPY IN SALEM

Land cover results of this study indicated that in 2018, 24% of the Salem UGB was tree canopy (or 9,202 acres of the 38,740 total acres); 22% was non-canopy vegetation (8,650 acres), 11% was soil/dry vegetation (4,433 acres), 40% was impervious (15,359 acres); and 3% was water (1,097 acres). Urban tree canopy (UTC) and possible planting area (PPA) results are based on land area which is equal to the total area minus water area (38,740 – 1,097 = 37,644 acres).Trees on tree farms and orchards were removed from the overall canopy cover due to their agricultural and transitional nature (98 acres). The resulting UTC cover was 24% (9,104 acres), 34% (12,763 acres) was suitable for future tree plantings, and 42% (15,778 acres) was unsuitable due to its current land use or other constraint. In further dividing the City’s urban tree canopy, 11% was overhanging impervious surfaces, and 89% of all canopy was overhanging pervious surfaces. Salem gained 5% (1,992 acres) urban tree canopy since
2009.

Fill out the form to access the full Urban Tree Canopy Assessment