x, 81 p. : ill (some col.) / This study investigates how two major groups of forest pests in North America, defoliating insects and bark beetles, influenced subsequent wildfire severity in the Booth and Bear Complex Fires. A secondary goal is to ascertain whether high-resolution plot-based vegetation data are better predictors of fire severity than lower resolution historical vegetation data. General Additive Models were used with an information-theoretic approach to determine the importance of forest insect outbreaks as predictors of fire severity. The models indicate that pest outbreaks were not significant predictors of fire severity and that high-resolution plot-based vegetation data are not superior to lower resolution historical vegetation data. Elevation and weather conditions were the most important controls of severity, while low-resolution vegetation data, slope and topographic position were of secondary importance. These results suggest defoliating insect outbreaks do not appreciably increase fire severity, though this finding should be verified in the context provided by other fires. / Committee in charge: Dr. Dan Gavin, Chairperson; Dr. Andrew Marcus, Member

The effectiveness of harvesting slash treatments are questionable when wild fires, fuelled by post harvesting slash, burn out of control. In order to quantify effectiveness of various slash treatments, fire behaviour in Pinus patula and Eucalyptus macarthurii compartments in the Highveld area (Piet Retief) of Mpumalanga, South Africa, were assessed after application of five different post-harvesting slash treatments. Treatments included mulching, chopper rolling, windrowing, removal of slash (inter-windrowing) and broadcasting. Independent fuel and environmental variables were measured prior and during application of fire to the study areas and effects on fire behaviour were compared afterwards. Dependant fire behaviour variables such as the rate of spread, fire temperature and flame height were measured in respective slash treatment plots and compared. Results of the study indicated that fire behaviour assessed in mulched areas in both the P. patula and E. macarthurii compartments were significantly less intense when compared to fire behaviour in chopper roll, broadcast and windrow treatments. Fire behaviour in mulched plots compared favourably with areas where harvesting slash was removed (inter-windrow treatment). Comparisons between fuel loads of different treatments also indicated accelerated mineralization of organic material in mulched areas. Mulching of harvesting slash seems to be an effective method to restrict fire behaviour in post-harvesting compartments and should be considered as part of a fire management strategy.

Firebrands, small pieces of burning vegetation or debris generated by fires, are one of the primary ways wildfires ignite structures. Due to their small size, firebrands can be carried several kilometers by high winds before landing on combustible surfaces such as decks or roofs and potentially igniting homes. Until recently, little has been known about the heat transfer capabilities of firebrands to the surfaces on which they land. Understanding the heat transfer from firebrands is an essential step in engineering for greater fire resilience. In the first phase of this research, heat transfer from individual firebrands to horizontal surfaces was investigated using oak firebrands made from commercially available lumber. The firebrand shape, wind speed, and wind direction were varied to see how these variables affect the heat transfer. A method of inverse heat transfer analysis based on infrared thermographs was used to measure distributed heat fluxes from firebrands to the surfaces through time. This measurement technique provided spatial resolutions of < 0.5 mm, approximately 10 times higher than previous experiments in this field. Results showed that localized heat transfer was significantly higher than had previously been reported, reaching as high as 80 kW/m2 in some cases. It was also found that wind speed, wind direction, and firebrand shape all affected the heat transfer from individual firebrands. Firebrands have also been shown to accumulate in piles on decks or roofs creating complex systems that have different ignition capabilities than individual firebrands. Potentially many factors could influence the heat transfer from firebrand piles including wood moisture content, wood type (hardwood or softwood), wood density, wood state (live, dead, or artificial), wind speed, pile mass, firebrand diameter, and firebrand length. The second phase of this research used the same method of high-resolution heat transfer measurement to assess which of these factors significantly impacted the heat transfer from firebrand piles. Design of experiments was used to develop the test matrices and a rigorous statistical framework was employed to evaluate results at the α=0.05 level. It was found that wind speed, firebrand length, and an interaction between firebrand length and diameter were important. Additionally, it was found that there was a difference between the heat transfer from piles made with artificial and real firebrands, suggesting that using dowels as surrogate firebrands may produce higher heat fluxes than expected from real firebrands. Pile mass did not appear to significantly impact the heat flux from firebrand piles. The last phase of this research developed a simple engineering model to predict the ignition of common building materials by firebrand piles. The model used time-varying heat transfer data from firebrand pile tests and material properties developed by testing on select building materials in a cone calorimeter. The model predicted the surface temperature rise of the material due to an exposure heat flux with ignition being predicted when the surface temperature exceeded the ignition temperature of the material. The model was used to predict ignition for a number of pile/fuel combinations and experiments were run to validate the predictions. It was found that the model did an excellent job in predicting ignition for materials which did not melt. Together this research provides an important step in understanding heat transfer from firebrands and firebrand piles, predicting ignition, and engineering for greater fire resilience. / Master of Science / Uncontrolled wildfires burning close to human civilizations result in hundreds of deaths, the destruction of thousands of structures, and billions of dollars in economic damages each year. One of the primary ways wildfires ignite structures is through firebrands: small pieces of burning vegetation or debris generated by the fire. These firebrands can be carried great distance by strong winds, eventually landing on decks or roofs and potentially igniting homes. Until recently, little has been known about the heat transfer from firebrands to the surfaces on which they land. Understanding firebrand heat transfer will allow building materials to be selected that are resistant to ignition by firebrands and reduce the number of structures destroyed by wildfires. In the first phase of this research, heat transfer from individual firebrands was investigated. The firebrand shape, wind speed, and wind direction were varied to see how these variables affect the heat transfer. A high-resolution measurement technique was used, allowing heat transfer to be measured with approximately 10 times higher resolution than previous experiments. Results showed that localized heat transfer was significantly higher than had previously been reported and indicated that wind speed, wind direction, and firebrand shape all affected the heat transfer from individual firebrands. Firebrands have also been shown to accumulate in piles on decks or roofs creating complex systems that have different ignition capabilities than individual firebrands. Potentially many factors could influence the heat transfer from firebrand piles including wood moisture content, wood type (hardwood or softwood), wood density, wood state (live, dead, or artificial), wind speed, pile mass, firebrand diameter, and firebrand length. It was found that wind speed, firebrand length, and an interaction between firebrand length and diameter were important. Additionally, it was found that there was a difference between the heat transfer from piles made with artificial and real firebrands. The last phase of this research developed a simple engineering model to predict the ignition of common building materials by firebrand piles. The model used time-varying heat transfer data, and material properties developed by experimental testing. The model was used to predict ignition of select building materials with different firebrand piles, and experiments were run to validate the predictions. It was found that the model did an excellent job in predicting ignition for materials which did not melt.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 25, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dissertation advisor: Dr. Richard P. Guyette. Vita. Includes bibliographical references.

The annual cycles of human- and lightning-caused fires create distinct patterns in time and space. Evaluating these patterns reveals intimate relationships between climate, culture, and ecoregions. I used unique graphical visualization techniques to examine a dataset of 516,691 records of human- and lightning-caused fire-start data from the western United States for the 20-year period 1992-2011. Human-caused fires were ignited throughout the year and near human populations, while lightning-caused fires were confined almost exclusively to the summer and were concentrated in less-populated areas. I utilize graphs and maps to demonstrate the benefit of a longer time frame in strengthening the findings and describing the underlying interactions among climate, society, and biogeography. / 2016-01-14

Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 100-112).

Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 84-90). Also available on the World Wide Web.

Strategic management of wildlands for fire is increasingly a mix of traditional firescience, climatology and human perceptions. Not only must managers be expert atmodeling fuels and fire behavior, they must also understand human behavior, and theeffects of climate on landscapes. We hypothiszed that areas in national forests differspatially in their importance to stakeholders, including both the public and landmanagers. That this difference is based upon the inclusion of factors not typically foundin wildland fire models. To test this hypothesis we used a multidimensional approach toassess the spatial variability several factors including recreation, property values and fuelmoisture. This approach combined a geographic information system with the analytichierarchy process to predict and test the current distribution of areas in national forestsimportant to stakeholders.Inclusion of stakeholders appears to improve the validity and useability of aspatial decision support system. Comparing the model created in this dissertation withseveral others demonstrates that it is important to strike the right balance betweenstakeholders and technical experts when designing and creating a model. It is alwaysbeneficial, however, to a significant level of stakeholder involvement.Areas important for fire mitigation efforts depended on the stakeholder oraudience rating the model. Raters from the U.S. Forest Service tended to favor areas withhigh fire probability scores, while those from the Park Service prefered recreation areasand places people value. In both cases, locations people had easy access to, such as alongroads and trails were favored.These results confirmed the hypothesis that areas of importance are differentbased on the individual rating the model. Further testing and refinement of the modelincludes expanding the study area beyond the southwestern United States as wells asobtaining better sources of data with finer spatial resolutions.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 16, 2007) Includes bibliographical references (p. 46-47).

Thesis (Ph.D.)--University of Melbourne, School of Resource Management and Amenity Horticulture, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 373-392).