COS 120-2 - CANCELLED - Quantifying urban forest attributes and ecosystem services to aid in developing sustainable management strategies in two western US cities

Background/Question/Methods

Urban forests provide a wide range of environmental, social, and public health benefits but have often been overlooked in traditional forest inventories. In recognition of the need for data describing urban forest conditions to inform sustainable urban forest management, the USDA Forest Service’s Urban Forest Inventory and Analysis program (Urban FIA) has implemented a long-term monitoring program focused on the urban forest resources of the United States’ most populous cities. Full inventories of the urban forests of San Diego, California and Portland, Oregon were completed in 2017 and 2018, respectively, representing the first two West Coast cities to join the Urban FIA inventory. Inventory data in these cities were collected across both public and private ownerships and describe urban forest attributes including tree species composition, number of trees, tree health, carbon storage and sequestration, and tree biomass. FIA has also partnered with the USDA Forest Service’s i-Tree team to provide estimates of ecosystem services provided by urban forests, including air pollution removal, avoided stormwater runoff, reductions in energy consumption, and associated monetary values.

Results/Conclusions

The most common urban trees (≥ 5.0 inches in diameter) were Phoenix roebelenii, Salix lasiolepis, and Arecastrum romanzoffianum in San Diego, and Acer macrophyllum, Pseudotsuga menziesii, and Thuja occidentalis in Portland. Trees in San Diego were estimated to store about 289,000 tons of carbon and remove about 34,600 tons of carbon and 421 tons of air pollution per year. Portland’s urban trees were estimated to store about 1.6 million tons of carbon and to remove about 51,000 tons of carbon and 500 tons of air pollution per year. The overall compensatory values of San Diego and Portland urban forests were estimated at $4.7 and $5.8 billion, respectively. Each city has unique forest health challenges, including threats from pests and diseases, population growth, drought, and wildfire. Future analyses of city’s urban forests can be used to determine the role that natural and human forces play in shaping forest structure and composition. For now, managers can use the data collected by the Urban FIA program to inform long-term management plans aimed at sustaining a healthy urban tree population and associated ecosystem services for future generations.