Geomorphic response to restoration and disturbance: Grazing, fire, and flooding on the Middle Fork John Day River, OR
Date
2011-03
Authors
Michelsen-Correa, Stephani
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
Salmon habitat restoration is ongoing at a Nature Conservancy preserve on the Middle Fork John Day River in the Columbia River Basin in north-central Oregon. The site has a long history of disturbance including dredge mining upstream, channelization, grazing, logging, fire, and floods. Using historic aerial photos, habitat unit surveys, and cross sectional profiles, this thesis shows how the channel morphology, particularly habitat unit diversity, has changed since 1939, just before placer mining began. Results show that the dominant influence on present day channel morphology is channelization from the 1930's. Other changes including dredge mining in the late 1930's to early 1940's, cessation of cattle grazing in 1991, and a fire followed by a flood in the winter of 1996-1997, had less impact because of the straightened, stabilized channel morphology.
Description
xii, 64 p. : ill. (some col.), maps
Keywords
Oregon, Disturbances, Ecological, Fluvial geomorphology, Restoration ecology -- Oregon -- John Day River, Middle Fork, Geography, Geomorphology, Environmental sciences -- Oregon -- John Day River, Middle Fork, John Day River, Middle Fork (Or.), Ecological disturbances -- Oregon -- John Day River, Middle Fork