Sponsor
Portland State University. Department of Geography
First Advisor
Teresa L. Bulman
Term of Graduation
Winter 1994
Date of Publication
1-20-1994
Document Type
Thesis
Degree Name
Master of Science (M.S.) in Geography
Department
Geography
Language
English
Subjects
Riparian ecology -- Oregon -- Johnson Creek, Salmonidae -- Habitat -- Oregon -- Johnson Creek, Nature -- Effect of human beings on -- Oregon -- Johnson Creek
DOI
10.15760/etd.7104
Physical Description
1 online resource (2, viii, 118 pages)
Abstract
Pacific salmon populations in Johnson Creek, Portland, Oregon have been adversely impacted by urbanization, and by residential and agricultural land development. Ecological impacts include loss or depletion of riparian vegetation features which directly influence stream and associated salmonid ecology. This research examines the nearstream riparian zone's contribution to instream habitat complexity for anadromous salmonids in Johnson Creek. Visual surveys were conducted on over half the stream length. Five features were assessed to determine the extent of riparian influenced stream habitat including, overhead enclosure, overhanging vegetation, undercut banks, and large and small woody debris and root wads. The stream survey showed that areas of riparian-influenced habitat are spatially intermittent and present in areas of the least stream disturbance. Suitable riparian habitat is limited to locations where there is minimal riparian disturbance, property management, and channelization. Although salmonid populations have been reduced, insufficient riparian influenced salmonid habitat features are not the primary limiting factor on salmon populations. Other factors such as pollution, sedimentation, hatchery fish introduction, low flows, inadequate food supplies, high stream temperatures, repress wild salmon populations.
Rights
In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
Persistent Identifier
https://archives.pdx.edu/ds/psu/30291
Recommended Citation
Gude, Andrew Greiff, "An Assessment of the Riparian-influenced Salmonid Habitat Features of Johnson Creek, Portland, Oregon" (1994). Dissertations and Theses. Paper 5232.
https://doi.org/10.15760/etd.7104
Plate 1. Zoning map showing areas of diverse land use in the Johnson Creek Basin (City of Portland 1992b, 12).
Gude_Plate2.png (138 kB)
Plate 2. Water quality problems in Johnson Creek Basin (City of Portland 1992b, 16).
Gude_Plate3.png (101628 kB)
Plate 3. The three reaches and nine surveyed sections. The consecutive numbers along the creek indicate river miles (Adapted from U.S. Geological Survey topographical maps for Lake Oswego, Gladstone, Damascus, 1984; and Sandy 1985).
Plate4.TIF (345404 kB)
Plate 4. Location of the Springwater Corridor Trail and areas of significant habitat along Johnson Creek (City of Portland 1992e).
Comments
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