Davey Resource Group

City of Portland, Oregon: The Cost of Managing Street Trees as a Public Asset

In 2008, the City of Portland, Oregon, hired Davey Resource Group (DRG) to undertake a unique urban forestry analysis. Currently in the city, the responsibility of maintenance for Portland's right-of-way (ROW) trees is directed to the owner of the adjacent property, not to the city. Since the city intends to plant an additional 80,000 trees, there became a need to explore ways that would ensure positive support from the community who would be sharing in the associated benefits and maintenance burdens.

Portland asked DRG to provide an initial assessment of the potential investment requirements for complete maintenance of street trees within the public ROW. Key personnel from the City of Portland collaborated with DRG to develop a suitable research method for anticipating potential investment levels associated with caring for the city's street trees. This research involved an investigation of costs and methods of urban forestry programs in other cities as well as an initial assessment of the potential investments required in Portland. Additionally, DRG provided an analysis that examined possible revenue sources for the city to consider that would support the maintenance of its street trees

The City of Portland had previously conducted an assessment of Portland street tree benefits using software models from the iTree suite of tools. (www.itreetools.org). DRG recognized this data as a resource for use in this project and built a cost model that leveraged their existing data and built on previous City research projects. The flexible cost model developed during this assessment provided a powerful tool to help the City of Portland determine practical maintenance schedules based on changing maintenance needs and budgets. By having this initial cost assessment and some comparison data from other cities, the City of Portland was able to demonstrate that although considerable investments are important to support their green infrastructure, the benefits provided by the trees still outweigh those costs.