Urban Trees

Urban trees in parks, natural areas, street-side, and on private lands combined with other GSI elements provide excellent opportunities to mitigate the effects of stormwater runoff. In collaboration with The Evergreen College, and Washington State Department of Ecology, phase I of this research focused on mature common native evergreen and deciduous trees based on the physio-climatic conditions of the Pacific Northwest. Phase II is focused on individual younger trees that tend to typify the type of trees growing in the urban environment.

Tree study at The Evergreen State College

Instruments were installed at 64 trees in two locations around the Olympia Area to determine transpiration rates of four species: Douglas-fir, western red cedar, bigleaf maple, and red alder. All 64 trees had instruments to measure sap flux, 36 measured canopy interception, and 24 measured stem flow.