Doctoral Dissertation Research: Fluvial Wood Presence and Dynamics Over a Thirty-Year Interval in Forested Watersheds

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This doctoral dissertation research project seeks to examine both the presence and transport of wood since logging ceased in the early 1980s by analyzing changes in fluvial wood and accompanying parameters within multiple Oregon Coast Range watersheds through the recreation of a field dataset first collected in 1978 by Marston.The cessation is attributed to increased forest conservation and management due to the designation of the Northern Spotted Owl as an endangered species and the implementation of Northwest Forest Plan regulations. The effects of this forest conservation and subsequent afforestation on the river systems are currently unclear. Thirty years later, the researcher expects that some of this fluvial wood has moved, some has remained, and some new wood has been imported. This study seeks to answer three research questions based on the comparison of the two field datasets. (1) How have the volume, size, and type of fluvial wood changed in Oregon Coast Range watersheds between 1978 and 2010? (2) What stream channel morphology changes have occurred due to fluvial wood in these watersheds since 1978? (3) How have the effects of afforestation changed the landscape of fluvial wood since 1978? The fourth research question regards the use of remotely sensed data to determine the presence of fluvial wood in forested watersheds as an alternative to the current labor intensive field collection methods. (4) Can fluvial wood be detected through airborne LiDAR data analysis coupled with ground-reference data, and how can these techniques be used to better monitor fluvial wood changes and better test fluvial theory?The results of this project will provide insight into fluvial wood characteristics in the Oregon Coast Range on a basin and inter-basin scale. This is a distinctive opportunity to examine the dynamics of wood in rivers over a thirty year interval to reveal the process of afforestation that has occurred in the study area. The results will also provide understanding into some less obvious impacts of clear cut harvesting, such as changes in tree species that significantly alter the types and volumes of wood in the rivers. There is an urgent need for research in watershed-scale river restoration efforts globally. Researchers worldwide might very well embrace the key component of restoration which this work renders which is, quantifying stream health through inventory of river complexity. An important contribution to achieving watershed-scale fluvial wood research is the examination of using LiDAR data for wood identification. Success of this technique in such an extremely wooded environment will determine the extents that LiDAR imagery may be used for wood detection. The support of this research through a Doctoral Dissertation Research Improvement award will enable a promising student to establish a strong environmental research career.