Graduate Project
 

A georeferenced digital image analysis of micro-topographic patterns within the Willamette Floodplain Research Natural Area, W. L. Finley National Wildlife Refuge

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https://ir.library.oregonstate.edu/concern/graduate_projects/8c97kr10n

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  • The present day vegetation pattern of the Willamette Valley is a result of a long past of human alteration of the landscape. Beginning with aboriginal burning of the grasslands to present day land uses, the vegetation of the valley has been affected by anthropogenic activity. Wet prairie is a vanishing habitat of the valley as both urban and agricultural development continue to alter the landscape. The W.L. Finley National Wildlife Refuge of the south-central Willamette Valley contains within its boundaries one of the last remaining examples of open wet prairie. In order to maintain the prairie community complex and associated biodiversity of the Willamette Valley Floodplain Research Natural Area, a restoration project in which controlled burning plays a significant role was initiated. As a part of the on-going research a need was felt to develop a baseline data base identifying the spatial distribution of principle features of the research area and to map the vegetationally associated mount-intermound micro-topographic pattern prevalent throughout the refuge. The purpose of this research project was to develop that baseline spatial data base and to investigate the use of digital image processing and analysis as a tool for inventorying micro-topographic features and associated open wet prairie vegetation patterns. This paper is primarily a methodological study of applying geographic techniques to an on-going biogeographical study This study had three objectives: (1) defining the location and boundaries of treatment spaces and sampling plots in a standard geographic coordinate system, (2) delineation of spaces and plots onto a scanned image creating a spatial data base and (3) classification of vegetation and associated microtopography. The aim of this study is to provide an evaluation of appropriate geographic information technology for the planning and analysis of wetland restoration and management. The objectives of this study were met with varying degrees of success. The use of Trimble's Global Positioning System, IDRISI's low-cost image processing/ Geographic Information System software and a small scale, color aerial photograph scanned to a single band, monochromatic digital image were utilized to create a suitable visual and spatial data base. Classification of the image into micro-topographic class was conducted using three strategies. Two standard supervised classification algorithms were compared using signatures generated from the original single band image. The influence of including signatures created from an additional data band based on digital richness of the original image was also examined. Information provided by the single, wide spectral space image was lacking and hampered classification of vegetationally associated micro-topographic patterns. The addition of signatures based on a created Relative Richness band did not appreciably effect classification accuracies. Regardless of classification strategy, insufficient separability of class signatures led to overall classification accuracies of +1- 70%. A high level of misclassification occurred within the intermound region resulting in overrepresentation of the mound micro-topographic pattern. The resulting thematic map was created using signatures generated from the original single band image and maximum likelihood classification routine.
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  • File scanned at 300 ppi (Monochrome, 8-bit Grayscale, 24-bit Color) using ScandAll PRO 1.8.1 on a Fi-6670 in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
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