http://hdl.handle.net/1957/7863 Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/9168 Title: Variations in gravel bed composition of small streams in the Oregon Coast Range <br/> <br/>Abstract: A study of the temporal and spatial variability of stream gravel bed composition and the factors affecting the amount of fine sediment within the bed was conducted in the streams of the Oregon Coast Range. Streambed samples were obtained by frozen core techniques and the amount of sediment smaller than 1.0 mm in diameter was expressed as a percentage by weight of the total sample. The amount of fine sediment in stream gravel beds was found to be highly variable in time and space. Temporal variability in percent fines was caused by flushing of fines from the gravel beds during high streamfiow events. This flushing of fine sediment seemed to occur randomly during winter freshets. Seven of 13 total streambed sample locations on five small streams showed trends of decreasing amounts of fine sediment during the winter high streamflow season. The percent fines within the stream bed was also found to display large variation (a) between streams, (b) between locations in the same stream, and (c) between locations in the same riff 1. Bed samples were collected on 21 watersheds in the Coast Range during the summer of 1978. The amount of fine sediment averaged 19.4% and ranged from 10.6% to 29.4%. Comparisons between locations on the same stream showed bed composition to be highly variable. Approximately 75% of the bed composition comparisons were significantly different at the 95% confidence level. One gravel bed was sampled on a 1.2 by 1.2 m grid design and significant (95% confidence level) changes in percent fines were found to exist both perpendicular and parallel to the stréamflow in this small area of the stream. Regression analysis on the samples collected on the 21 streams indicated that the amount of fine sediment in the bed is influenced by the slope, area, relief, and land use characteristics of the watershed. Within a single stream, however, regression analysis indicated that gravel bed composition was dependent on sinuosity and ankful1 stage. These two variables suggest that the intrusion of fines into the stream bed is influenced locally by hydraulic conditions within the channel. Regression analysis and field observations suggest that the amount of fine sediment in stream gravel beds might be increased by road construction and logging operations. However, increases in levels of bed fines after disturbance should be temporary due to the flushing of fines with high flows. <br/> <br/>Description: Graduation date: 1980; Presentation date: 1979-05-29 http://hdl.handle.net/1957/9167 Title: A mechanized harvesting system simulation : input, output, limitations and capabilities <br/> <br/>Abstract: This study concerns the use of a discrete-event simulation model for analyzing the production of a mechanized forest harvest system. The simulation models a field collection data set of a harvester-forwarder system which was previously collected by the Forest Engineering Department of Oregon State University. The computer software consisted of the statistical package Statgraphics and the simulation package Promodel PC. Special emphasis is given to the use of statistical distributions and linear regressions as simulation input data. The simulation model was built in productive machine time. Input quality and output capabilities of the simulation language Promodel PC produced realistic output of weekly predicted production of the system. Also, linear regressions of average yarding distance and unloading time of the forwarder estimated the production of the harvest system. The unloading time regression was used to develop a cost evaluation of the possibility of adding a loader to the harvest system. Group and ungroup" functions of Promodel PC are powerful tools for generating a simulation model of a harvest system. These functions allow an easy programming transition despite the different system products. On the other hand, animation produced more model building difficulties than output benefits. It is advisable for future field studies to be designed in a different manner. Variables should be collected according to the input needs of the simulation model. <br/> <br/>Description: Graduation date: 1995; Presentation date: 1994-07-22 http://hdl.handle.net/1957/9098 Title: Assessing the sustainability of management practices for planted forests across an environmental gradient in New Zealand <br/> <br/>Abstract: Sustainable management of planted forests requires maintenance of soil function to promote 1) root growth; 2) storage and cycling of water and nutrients; 3) optimal gas exchange; and 4) biological activity. Soil quality measurements can be used to monitor short- and long-term changes in these soil functions, allowing managers to track sustainability elements over time. I measured selected key soil processes (nitrogen (N) mineralization, decomposition, and soil water dynamics) which regulate soil function during the final year of growth (year 4) on highly stocked plots (40,000 stems ha⁻¹) at ten sites distributed across New Zealand in order to investigate impacts of soil disturbance (low vs. high), fertilization (fertilization vs. none), and tree species selection (Pinus Radiata D.Don vs. Cupressus lusitanica Mill.) on those soil processes. Secondly, I developed a quantitative forest soil quality index (FSQI) that is applicable across the complex environmental gradient in New Zealand. Treatment effects on N mineralization and decomposition were site-specific. Effects of soil disturbance depended on initial soil physical conditions, rainfall patterns, or soil fertility levels. Fertilization effects were most often observed at sites with low fertility. Tree species effects were more pronounced at sites with low rainfall, low soil N, and low sum of bases (Ca, Mg, K, Na). Response of soil water dynamics to treatments was consistent across the gradient. P. radiata had more optimal conditions compared to C.lusitanica, whereas fertilized plots had more days with wet soil conditions and fewer days with dry soil conditions compared to unfertilized plots. These results suggest that site-specific recommendations are necessary for appropriate management of N mineralization and decomposition processes, whereas a more general approach is sufficient when considering soil water dynamics. The FSQI developed through this research was based on sufficiency levels of key soil (A horizon depth, bulk density, C:N ratio, Olsen P) and climate (air temperature) indicators for forest productivity, and provided data for calculation of forest soil quality of both P. radiata and C. lusitanica plantations, with and without fertilization. The final FSQI was correlated with tree growth and soil processes, and provides a useful tool for measuring soil resource sustainability elements in New Zealand. <br/> <br/>Description: Graduation date: 2009 http://hdl.handle.net/1957/8902 Title: Evaluation of a prototype NIR system for Douglas-fir wood density estimation <br/> <br/>Abstract: Forest products companies in the U.S. face vigorous competition from other wood producers around the world and other industries (steel, aluminum, plastics, composites). To be competitive, forest companies need to control costs, sort and allocate logs to the most appropriate markets, and recover more value at time of harvest. Interest in log sorting based on internal wood properties is increasing. Wood properties, such as stiffness and density, are now being considered by log buyers. Assessing these properties in-forest and in real-time will be a challenge for log supply managers. The utility of near infrared (NIR) technology for measuring wood density is showing promise in laboratory conditions. The rationale behind this study was to evaluate NIR under conditions that are similar to field harvesting operations to estimate log density. Douglas-fir wood samples (110 disks) were collected from the McDonald-Dunn forest and processed in the OSU Oak Creek laboratories. Processing conditions were organized to simulate a harvester processor environment by using a chainsaw, and then channeling the chips with a chute to concentrate chips to move past an NIR sensor. This apparatus was intended to mimic a sensor system fitted to a harvester head.. A rugged Prospectra D² NIR sensor was used to collect spectral data. The generated spectra were analyzed in two forms, as raw data (without any transformations) and a transformed data (2nd derivative). Then, four types of calibration models were applied to predict log density: (1) models that used tree parameters only as a predictor (the simple model), (2) models that used NIR absorbance data and Partial Least Squares (PLS) analysis procedures , (3) models that used NIR absorbance data and Multiple Linear Regression (MLR) analysis procedures, and (4) models that used a mix of NIR absorbance data and tree parameter data and MLR analysis procedures. The goal of the models was to use the NIR data to predict the density of the log that has been cut. Model results were also obtained for validation (full cross validation) and calibration sets. Data analysis suggests that correlations for calibration sets (R) were high, but when validation was applied there were large drops in R values. The best fit model was the simple model, the model that did not include NIR data as predictors. Our interpretation of why the simple model was the best fit is that there is great variability of wood characteristics across the stem section, that there was morphological problems associated with how we presented the samples, and that we used a narrower spectral range of NIR compared to the range used in earlier studies. <br/> <br/>Description: Graduation date: 2009