Submission Title

Growth and Survival of Western Red-Cedar Seedlings in Forest Park

Location

Jereld R. Nicholson Library: Grand Avenue

Subject Area

Environmental Studies: Science Focus

Description

In 2005, western red-cedar (Thuja plicata) seedlings were planted in Forest Park in Portland, Oregon to ascertain whether mammalian predation had a role in low seedling recruitment in the park. Nine study sites, three in each section (city, middle, and far) of the park were located along an urban-rural land use gradient. At each site, 27 seedlings were planted. Each tree was randomly assigned to one of three groups: deer exclusion, rodent exclusion, or control. Each was measured prior to installation of exclusion devices (March 2005). Tree height, width, basal diameter, percent of branches grazed and mortality rate has been measured annually. All trees were remeasured in the summer of 2015. Trees grew better in the far section of the park in terms of increased height and basal area. Grazing was highest in the middle and far sections. Tree mortality was lowest in the far section and highest in the city. Our findings suggest factors related to urbanization are impacting seedling survival in Forest Park.

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Growth and Survival of Western Red-Cedar Seedlings in Forest Park

Jereld R. Nicholson Library: Grand Avenue

In 2005, western red-cedar (Thuja plicata) seedlings were planted in Forest Park in Portland, Oregon to ascertain whether mammalian predation had a role in low seedling recruitment in the park. Nine study sites, three in each section (city, middle, and far) of the park were located along an urban-rural land use gradient. At each site, 27 seedlings were planted. Each tree was randomly assigned to one of three groups: deer exclusion, rodent exclusion, or control. Each was measured prior to installation of exclusion devices (March 2005). Tree height, width, basal diameter, percent of branches grazed and mortality rate has been measured annually. All trees were remeasured in the summer of 2015. Trees grew better in the far section of the park in terms of increased height and basal area. Grazing was highest in the middle and far sections. Tree mortality was lowest in the far section and highest in the city. Our findings suggest factors related to urbanization are impacting seedling survival in Forest Park.