A Georeferenced Digital Image Analysis of Micro-topographic Patterns within the Willamette Floodplain Research Natural Area, W.L. Finley National Wildlife Refuge by Karen L. Anderson A Research Paper submitted to The Department of Geosciences Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Geography Program February 1996 directed by Dr. Philip L. Jackson ABSTRACT 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 over- representation 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. TABLE OF CONTENTS CHAPTER PAGE ABSTRACT INTRODUCTION Objectives Historical Background 2 STUDY SITE General Setting and Environment 6 Concurrent RNA Ecological Research 8 METHODS General Approach 14 Ground Point Location Determination 15 Data Base Development 17 Rectification and Georeferencing 19 Creation of Vector Files 20 Digital Image Classification 20 Creation of Relative Richness Band 21 Treatment Space Division 22 Development of Training Site Vector Files 23 Development of Training Signatures 25 Application of Classification Routine 25 Maximum Likelihood Classifier 25 Minimum Distance Classifier 26 Cartographic Output 27 RESULTS Global Positioning System 28 Pre-Classification Vegetation Sampling Plot Characteristics 29 Training Site Statistics (signatures) 33 Vegetation Plot and Training Site Histograms 33 Image Classification Accuracy Assessment 37 DISCUSSION Global Positioning System 45 Classification 45 CONCLUSION 54 REFERENCES 56 APPENDICES 58 LIST OF FIGURES FIGURE PAGE Location of the Willamette Floodplain Research Natural Area, 7 W.L. Finley National Wildlife Refuge in reference to the Willamette Valley, Oregon (Streatfeild-Welch 1995). 2 Burn history of research units within the Willamette Floodplain 9 Research Natural Area. 3 Delineation of research units and distribution of permanent vegetation 11 sampling plots overlaid upon an output image of the original single band digital color image. 4 Schematic of a mound associated vegetation plot, digitizing guide 24 lines, and training areas used for signature development. 5 Histograms of digital numbers representing vegetation plots masked 34 from the original single band image. 6 Histograms of digital numbers representing class signatures from 35 training plots masked from the original single band image. 7 Histograms of digital numbers representing class signatures from 36 training plots masked from the Relative Richness pseudo image. 8 Thematic map representing the micro-topographic pattern of the 44 Willamette Floodplain Research Natural Area, W.L. Finley National Wildlife Refuge. LIST OF TABLES TABLE PAGE Research space statistics derived from vegetation sampling plots for 30 the original single band image. 2 Training site statistics from the original single band image. 31 3 Training site statistics from the Relative Richness pseudo image. 32 4 Classification assessment of vegetation plots based upon the size of 38 the training samples by space and topographic class. 5 Plot assessment of classification accuracy of the maximum likelihood 42 routine based training sites form the original image. 6 Percentage of area classed as mound or intermound by 43 space and classification routine. LIST OF APPENDICES APPENDIX PAGE Indigenous uses of plant species found in the Willamette Floodplain 58 Research Natural Area, WI. Finley National Wildlife Refuge. 2 Global Positioning System rover and Community Base-station 59 parameter settings used in this research project. 3 Global Positioning System rover display data recorded before 60 and after each positional reading. 4 Differentially corrected GPS determined UTM locations of the 61 northwest corner for the 38 permanent vegetation plots (1- 2.54 meter accuracy). 5 Differentially corrected GPS determined UTM locations of the 64 northwest corner for the six 1983 research plots (+I 2.54 meter accuracy). 6 Positional Readings of USGS Superstation (El 11). 65 INTRODUCTION The present day vegetation pattern of Oregon's Willamette Valley reflects a history of human manipulation of the natural landscape. Annual burning of prairies by Native Americans, cessation of burning with settlement and the introduction of grazing, logging and agriculture together with the continued expansion of agricultural clearance, alteration of natural drainage patterns, and urbanization profoundly influenced the vegetation composition and structure found in the Willamette Valley. Today, the Willamette Floodplain Research Natural Area in W.L. Finley National Wildlife Refuge protects what is thought to be one of the few remaining examples of relatively unaltered open wet prairie.In the absence of fire and/or grazing the prairie would revert to forest.In order to restore and maintain the disclimax prairie in a condition similar to that at the time of settlement, a rigorous prescribed burning program was initiated in the Research Natural Area in 1990. It is the purpose of this research paper to investigate the use of digital image analysis as a tool for inventorying micro-topographic features and associated open wet prairie vegetation patterns. 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. Objectives As a part of the controlled burning program, long term research is being conducted to assess and document the topographic and ecological conditions of the Willamette Floodplain Research Natural Area (RNA). The objective of this study was to use digital image processing and classification techniques to develop a baseline geographic data base that would: (1) map the boundaries of the RNA and research burn units, (2) map the spatial distribution of permanent vegetation sampling plots within the RNA, and (3) map the vegetationally associated mound-intermound micro-topographic pattern of the RNA. To accomplish these objectives, I gathered spatial data using Global Positioning System (GPS) technology, mapped the spatial data with a computerized Geographic Information System (GIS) and identified and mapped the pattern of the vegetationally associated mound-intermound micro-topography. Mapping of the micro-topographic patterns was conducted using supervised classification techniques with available digital image processing and