GIS in Action 2024

A climate resilient city means understanding our most important environmental assets: trees. The Urban Forestry division of Portland Parks and Recreation (Urban Forestry) has been analyzing the urban forest through tree inventories and aerial imagery analysis for over a decade. This data is used to inform policy, direct tree planting efforts to help populations vulnerable to urban heat island effects. Through a regional partnership administered by Oregon Metro (Metro), the City of Portland has access to higher quality remote sensed data like LiDAR. For the LiDAR flights that took place in 2014 and 2019, Metro’s GIS staff took the raw data and generated a tree canopy raster for the region. Metro’s methodology included shape-based data cleanup and shadow removal. Discovering the comparability between the datasets from the different years was also an important part of the data processing. With the canopy datasets created by Metro publicly accessible, Urban Forestry was able to analyze Portland’s tree canopy even further by identifying canopy cover citywide as well as across local authoritative boundaries. Many of the analyses on canopy cover were made into maps and aggregated into a public tool called Tree Canopy Explorer PDX. When opportunities for interagency collaboration occur, more informed decision making can happen; just as the discussions between Metro and the Urban Forestry on the LiDAR derived canopy data helped make the Tree Canopy Explorer tool possible.