by Julie Fukuda, Botanic Specialist I - Forestry
Following the completion of Portland's Street Tree Inventory in 2016 and embarking on a Park Tree Inventory the following year, we now have a clearer understanding of the extent and condition of Portland’s urban forest within City-owned parks and public rights-of-way. This brings us to a new project which will include trees on other land use types within our city: residential, commercial, industrial, institutional land, as well as publicly-owned land. The Urban Forest Inventory & Analysis (Urban FIA) currently underway in Portland will add valuable inventory data to help us complete the picture of Portland’s tree canopy with sampling across public and private lands.
What is Urban FIA?
Portland’s Urban FIA, a partnership with the US Forest Service Pacific Northwest Research Station, is an extension of the Forest Inventory and Analysis (FIA) which has provided a forest census for the US since 1930. Since 2014 the Urban FIA has combined the traditional rural-focused FIA with methods and protocols used to estimate the quantity, health, composition, and benefits of urban trees, adding new cities each year in pursuit of a cohesive picture of urban forest conditions in the nation. Urban FIA map and program details are available here.
In the summer of 2018, PP&R Urban Forestry staff will collect baseline data in 200 field plots which will be established for long term monitoring. During fall and winter 2018, data analysis will occur using i-Tree, a software tool for analyzing the health, composition and benefits of trees. Reports will be publicly available in traditional formats, as well as via the My City’s Trees Application, an online tool designed for public access to Urban FIA data and customized analyses and reports.
Trained Urban Forestry staff determine tree locations within sample plot boundaries.
How will the study be conducted?
Two hundred randomly generated 1/6-acre sample plots are distributed throughout Portland. Plots are circular and measure 96 feet in diameter. To get an accurate picture of tree distribution across the city, all zoning classes and land use types are included: examples include forested parks, parking lots, back yards, and even open water!
In the spring and summer of 2018, property owners with plots on their land will be contacted by Urban Forestry to request permission to access these sites. Physical access is critically important to obtain the most accurate information: are trees present or absent? This includes not only mature trees but seedlings and saplings too! Other data recorded includes tree species, tree numbers and size, tree crown width and condition, health condition, and information on the land surface conditions and other vegetation coverages within the sample plots. By law the plot location and owner’s name is kept confidential through a non-disclosure agreement. Urban FIA data will be publicly available in summary form only. Information collected as part of this inventory is not used for tax purposes, nor for regulation.
Urban FIA data collection follows standardized protocol developed by the US Forest Service. Urban Forestry staff were trained and certified in these protocols and must adhere to strict quality assurance requirement for data to be included in the study.
Plot areas may encompass streets, sidewalks and multiple properties.
How is the inventory data used and how will Portland benefit?
Over 80% of the U.S. population lives in urban areas and Portland is home for over 60% of our state’s population. In the U.S. urban areas cover about 68 million acres and are increasing. Our city’s population is growing at the rate of approximately 2% per year. PP&R Urban Forestry’s mission is to grow and ensure Portland’s tree canopy for present and future generations. This information will help us fulfill our mission by allowing us to:
- Monitor urban forest conditions continuously over time
- Determine impacts on our forest due to population pressures and changing climate
- Define service levels to meet the needs of all Portland residents
- Quantify monetary benefits trees provide to Portlanders as essential infrastructure
- Plan a resilience response to outbreak of pests and pathogens
- Compare our urban canopy performance with other cities nationwide
Urban Forestry staff attended an Urban FIA training to become certified by the US Forest Service in study protocol. Standardization of procedure allows for comparison with other US cities, nationwide.
Trees in our city play a crucial role in the health and well-being of all who live and work in Portland. In addition to the many environmental services that trees provide, trees also ensure a host of well-researched social, psychological, economic, and public health value to our population. Collecting detailed information on Portland’s trees and implementing a continuous monitoring system helps us manage this important resource for greatest community benefit.
Questions? Please email or call Nik Desai, PP&R Urban Forestry Urban FIA Project Manager