For the past 18 months, TerraFuture's research team has been conducting the most granular analysis of Portland's urban tree canopy ever attempted. Using a combination of LiDAR data from the Oregon Department of Geology, Sentinel-2 satellite imagery, and on-the-ground surveys by 84 trained volunteers, we have mapped canopy coverage at a resolution of 1 square meter across the entire Portland metropolitan area.
The results tell a story that is both encouraging and deeply concerning.
The Big Picture
Portland's overall urban tree canopy covers approximately 31.2 percent of the city's land area, which places it above the national average of 27 percent for cities of comparable size. However, that aggregate figure conceals enormous disparities at the neighborhood level.
Our analysis identified a 47-percentage-point gap between the most canopied neighborhood, Eastmoreland at 58.3 percent coverage, and the least canopied, Lents at 11.6 percent coverage. This gap is not random. When we overlaid canopy data with census tract demographics, the correlation between lower household income and reduced tree canopy was striking, with an r-squared value of 0.74.
Heat Vulnerability Connection
The canopy data becomes particularly significant when cross-referenced with temperature data from the 2021 heat dome event, during which Portland reached 116 degrees Fahrenheit. Neighborhoods with less than 15 percent canopy coverage experienced peak temperatures averaging 8.3 degrees higher than neighborhoods with greater than 40 percent coverage.
During that event, Multnomah County recorded 69 heat-related deaths. Our spatial analysis shows that 72 percent of those fatalities occurred in census tracts falling in the bottom quartile for tree canopy coverage. This is not a coincidence. It is a measurable public health crisis with a clear environmental driver.
The Planting Gap
Portland has committed to reaching 33.3 percent canopy coverage by 2035 under its Urban Forest Action Plan. Our data suggests the city is currently losing canopy at a rate of approximately 0.4 percent per year due to development, disease, and storm damage, while replanting efforts are adding roughly 0.25 percent annually. At this rate, the city will fall short of its target by an estimated 3.8 percentage points.
More critically, 81 percent of new tree plantings over the past five years have occurred in neighborhoods that already exceed 25 percent canopy coverage. The neighborhoods that need trees most are receiving the fewest.
The data makes the case clearly: we are planting trees where trees already exist, and the communities bearing the greatest heat burden are being left behind.
What Our Data Recommends
Based on this analysis, TerraFuture is proposing a targeted canopy equity initiative focused on 12 priority neighborhoods where coverage falls below 15 percent and heat vulnerability scores are in the top decile. Our modeling suggests that planting 8,000 trees in these areas over the next five years would reduce peak summer temperatures by 2.1 to 3.4 degrees Fahrenheit and prevent an estimated 12 to 18 heat-related hospitalizations annually.
The cost of such an initiative, approximately 4.2 million dollars including planting, establishment care, and monitoring, represents a fraction of the healthcare costs associated with heat-related illness in these communities, which we estimate at 6.8 million dollars annually.
Open Data Commitment
In keeping with TerraFuture's commitment to transparency, we are publishing the complete canopy dataset, methodology documentation, and analysis code on our open data portal. We believe this data belongs to the community and should inform planning decisions at every level.
We are also partnering with Portland State University's Toulan School of Urban Studies to integrate this data into their graduate planning curriculum, ensuring the next generation of urban planners understands the relationship between tree canopy, heat vulnerability, and environmental justice.
The trees are not just an amenity. They are infrastructure, and the data shows we need to invest in them accordingly.
