Forest Park’s “Old-Growth” Site

Report 1: Introduction to Forest Park’s Burlington Location

These series of field reports will be examining old growth forest conditions at Forest Park’s Burlington location. This 30 acre site is located about 13 miles northwest of downtown Portland and 3 miles northwest of the northern contiguous boundary of Forest Park. This section of forest is does not technically meet the definition for an old growth stand because there are too few large trees, snags and downed logs—the stand is also too small in size (Broshot 2007) (Franklin & Dyrness 1988). This stand does contain some of the oldest trees in Forest Park, with some Douglas-fir dated to approximately 445 years old (Broshot 1999). While the stand might not meet the technical definitions for an old-growth stand, it still retains structural and compositional features consistent with old-growth Douglas fir-Western hemlock coastal forest types.

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The location of the Burlington “old-growth” site. The site is managed by Metro and is open to the public. It is within the boundary of the Greater Forest Park Conservation Initiative, which seeks to protect and conserve land surrounding Forest Park.

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During my initial scouting trip to this site I spent time observing the different structural and composition features present in the stand. This included identifying the main tree species: Douglas-fir, Big-leaf Maple, Western hemlock, Western red cedar, Pacific yew and Red alder. There were many very large diameter Douglas-fir trees in this stand. I noted the uneven age classes present, with younger shade-tolerant species established underneath the older Douglas-fir. Also present was downed logs, and snags throughout the stand. I was able to find a Western hemlock seedling growing on a nurse log. There were also numerous Western hemlock saplings growing from old logs and stumps.

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  Mature Douglas fir next to a younger Western red cedar.

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  Western hemlock that established on a stump.

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  Snag with broken top.

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  Downed decomposing log.

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  Western hemlock seedling growing on nurse log.

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  Western hemlock saplings growing under canopy of mature Doug firs.

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I will be investigating shade-tolerant conifer regeneration for my thesis project and will be installing monitoring plots in this “old-growth” section of Forest Park. The data I collect will assist my project, but I also intend to use that data for this field report assignment. The overall goal for this assignment will be to characterize old-growth forest conditions both quantitatively and qualitatively. This will include taking field measurements of tree species, DBH, canopy coverage, course woody debris, seedling counts, substrate and herbaceous and shrub coverage.

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References:

Broshot N (1999) The effects of urbanization and human disturbance upon plant community structure and bird species richness, diversity, and abundance in a natural forested area (Forest Park) in Portland, Oregon. Doctoral dissertation. Portland State University, Portland, OR, p 244

Broshot, N. E. (2007). The influence of urbanization on forest stand dynamics in Northwestern Oregon. Urban ecosystems, 10(3), 285.

Franklin J, Dyrness CT (1988) Natural vegetation of Oregon and Washington. Oregon State University Press, Corvallis, OR, p 452