The wildland fire risk in Arizona is increasing due to shifting land uses, growing residential communities, and changing climate. As the fire hazard increases, land managers and fire educators are faced with educating wildland-urban interface residents about their risk to influence homeowner behavior. To determine how homeowners perceive their risk and what information they use to make decisions about risk and mitigation, this study surveyed residents in previously identified high risk areas in Arizona in three different vegetation types. Results show that ponderosa pine residents are more savvy about their risk and more active in mitigating that risk. Grassland and desert scrub residents consistently report a lower perceived risk to wildland fire than their forest counterparts and perform less mitigation. Results suggest that grassland and desert scrub communities may benefit from the production and dissemination of fire-related materials detailing risk specific to these areas.

Wildfires pose a growing threat for communities along the wildland-urban interface (WUI) around the world driven by a changing climate and expanding urban areas. One of the primary mechanisms by which fires can spread in the WUI are firebrands, airborne embers capable of acting as ignition sources carried in the airstream. Many studies have been conducted on the generation and transport of firebrands, but limited work has been conducted to quantify the heat transfer of firebrand piles to surfaces. A series of three studies are presented here exploring the heat transfer, burning, and material ignition of firebrands. In the first study, the differences between firebrands from structure and vegetation sources was compared. It was found that an ash layer in the vegetation firebrands reduced the heat and mass transfer. In the second study, impact of the surface geometries that firebrands accumulate on was explored. It was found that wall and corner configurations reduced the heat transfer the most and caused piles to burn from the wall surfaces outwards. Flat plate and decking configurations had the highest heat flux due to the lack of flow obstruction. In the final study, a framework was developed for predicting the material ignition resistance reliability exposed to a smoldering firebrand pile. The exposure was based on empirical relations for the heat flux from piles as a function of pile height, porosity, and wind speed. Cone calorimeter data was used to generate material thermal and ignition properties. With these inputs, the framework was used to predict the potential for material ignition thus circumventing the need for costly firebrand tests. This collection of studies provides evidence of the factors that drive firebrand burning behavior and heat transfer and links those aspects to the potential for ignition of construction materials. / Doctor of Philosophy / Wildland-urban interface (WUI) fires pose a growing threat for communities around the world driven by a changing climate and expanding urban areas. A particularly dangerous way that fires can spread long distances is via firebrands, burning particles that splinter off of trees or buildings that can be blown long distances by the wind. These firebrands can land onto surfaces like buildings and ignite those surfaces, causing new fires called spot fires. The science behind how firebrands ignite new surfaces is not well-developed, and there is no broad tool that can be used to predict whether a material or a building will ignite given certain conditions. The research presented here aims to address that lack of understanding by approaching the problem systematically, breaking down the individual driving elements of firebrand burning. First, the difference in heat transfer and burning behavior between firebrands from structures and from vegetation was explored. Second, the impact of various surface geometries was explored. The surface geometry of where the firebrands accumulate also influences the heat transfer of the firebrands. Finally, a framework for predicting the material reliability of materials to firebrand exposure is presented. Experimental correlations for firebrand burning based on pile parameters were generated and used to predict the heat fluxes from piles. The framework used material ignition data from cone calorimeter experiments to predict how materials would respond under thermal exposure. The framework compares the predicted exposure with the material ignition data to calculate the reliability. This collection of studies provides insight on the many factors that drive firebrand burning behavior and heat transfer and links those aspects to the ignition of materials.

Wildfire can be an extremely destructive force, especially when it reaches our nation's ever-increasing wildland-urban interface (WUI) area. To address this issue, state and federal agencies and cooperative education programs have begun to promote homeowner responsibility and wildfire vulnerability minimization practices as a means for WUI residents to take a proactive approach to protecting their homes from wildfire. This research provides resource managers with a new understanding of the processes through which WUI residents receive, interpret, and reconstruct wildfire messages, which will allow them to better assess their wildfire education programs. Results from this study suggest that WUI residents negotiate meanings for wildfire messages by externalizing and/or internalizing the hazard and its solution, and that these interpretations are strongly related to residents' behavioral response. This study also reveals significant discrepancies between WUI residents' central values and program goals; whereas fire programs generally highlight risk to homes and structures in the WUI, residents were typically far more concerned with their homes' contents and the environments within which their homes are situated. The insights provided by this study will increase program managers' ability to remedy these discrepancies and improve the effectiveness of wildfire vulnerability minimization programs and messages. / Master of Science

"The Wildland/Urban Interface, in which homes are intermingled with forested areas, presents unique challenges to fire protection and fire prediction, owing to the different fuel loads, conditions, and terrain. Computer models that predict fire spread through such an area require data for multiple scales, from crown fire spread to the heat release rates and ignition conditions for individual trees, as well as an understanding of fire behavior and spread. This discussion investigates a means by which fire behavior for Douglas-fir trees can be determined from quantifiable characteristics, such as height and moisture content. Mass, flame height, peak heat release rate, and total energy can be estimated from these simple measurements. A time scale of 60 seconds, combined with a peak heat release rate estimated from tree size characteristics, provides an approximation of total energy that is within 11% of measured values. Pre-heating of trees with a low (2.5 kW/m2) radiant heat flux did not have a noticeable impact on the resulting heat release rate. In addition, fire spread between trees was highly dependent on the presence of ambient wind; in the absence of wind or wind-borne embers, the trees were very resistant to ignition even when in close proximity (3 spacing). With the addition of wind, the fire would spread, although the heat release rates were dramatically reduced for trees of sufficiently high moisture content (< 70%)."

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226 pp. / UACE Firewise publications (8 total) / The Living with Wildfire in Arizona educational materials synthesize the most recent scientific and technically known information available on fire ecology for the ecosystems of Arizona, including mixed conifer forests, ponderosa pine forests, pinyon-juniper and oak woodlands, chaparral, grasslands and desert scrub, and riparian areas. The materials are meant to educate homeowners living in the wildland urban interface areas as to the natural function of fire in each ecosystem and what significant changes have impacted fire behavior over time. Information includes the natural role of fire, how and why fire behavior has changed over time, and the role that humans play in affecting that change in protecting themselves and their property.

Non-industrial Private Forests (NIPF) landowners constitute a major component of the forested land portfolio in the Southeastern United States. The lands they possess provide a variety of social benefits but many aspects of how these landowners manage their properties exist. The goal of this research was to determine overall landowner awareness regarding wildfire programs and education and identify interrelationships among management strategies, demographic variables, and experiences. Specifically, it was hypothesized that landowner program awareness, interest in biomass utilization, and wildfire mitigation strategies would be influenced by the type of information they received, management activities, and other factors. Seven logit models were constructed to analyze these interrelationships. Results revealed that the type and quality of information landowners received was important in most cases. Landowners not receiving any information were less likely to take action to prevent or mitigate wildfire damage to their property. Wildfire education was highly valued by participants. Knowledge of existing biomass utilization programs was almost non-existent. However, the desire to obtain information on this topic was high. In general, state agencies were utilized more than federal agencies, and landowners felt that cost-share programs and marketability of removed biomass would encourage participation in wildfire prevention activities.

The majority of the world’s population now lives in urban areas, and the peri-urban has grown simultaneously, creating new Wildland-Urban Interface (WUI) where development comes into contact – and intermingles with – wildlands. WUI has an elevated wildfire risk. This study examines current and future wildfire risk in the Acadian Forest Region, and consists of two papers. The first manuscript of this thesis describes a model to delineate WUI at a site-scale for municipal risk management, using fire behaviour modelling. The second manuscript uses climate and fire behaviour modelling, projecting an increase in fire weather severity in the Acadian Forest Region under climate change, indicating increased future fire susceptibility. Shifts in tree species composition may offset this risk, as tree species become a negative fire risk driver. The relative importance of fire risk drivers was solicited from experts to assess the net impact on fire risk. Together these papers identify an increasing fire risk in the region under climate change, depending on site-level tree species composition dynamics, and an opportunity for municipal management of fire risk. Delineation of WUI and risk management are necessary, given increasing future fire risk and uncertainty under climate change.

Degraded pollinator habitat may have far-reaching consequences for recovery of imperiled flowering plant populations. Studies indicate that broad-spectrum insecticides used in mosquito abatement are detrimental to non-target invertebrates, including pollinators. A decline in efficient pollinators can reduce plant fitness by decreasing reproductive output and constraining genetic diversity, a challenge for rare plants. In 2015, I monitored flower visitation and fruit set of three imperiled plant species throughout protected areas on three islands in The Lower Florida Keys. These islands consist of conservation land fragmented by intermittently dispersed residential neighborhoods that seasonally spray insecticides for mosquito control. Flowers open at treatment sites had decreased flower visitor activity following insecticide applications, but only species that require invertebrate agents for pollen transfer had significantly reduced fruit set. Implications of mosquito insecticides near conservation lands may pose immediate threats to invertebrate pollinators and flowering plants that require pollinators for reproduction, although long-term threats to genetic diversity are unknown for automatic self-pollinating species.

Wildfire hazard is increasing in much of the United States, posing a threat to human communities and natural ecosystem services, especially in areas at the wildland-urban interface. There are steps people can take to reduce wildfire hazard, but often they are not used. Understanding and addressing human perceptions of wildfire risk and of risk-mitigating behaviors requires knowledge of both social and ecological systems. To better understand this complex issue, three types of factors must be addressed: social, cultural, demographic, and biophysical. This dissertation incorporates these three essential factors to intensively investigate the risk perception and behaviors of residents living in wildland-urban interface communities in three states (Arizona, California, and New Mexico). The first study examines the effect that individual risk perceptions have on intention to mitigate wildfire risk by integrating two social-psychological theories, Theory of Planned Behavior and Cultural Theory, to investigate the causal relationship and motivational factors that influence the intention to mitigate wildfire hazard. Results suggest that attitudes toward wildfire mitigation practices and perceived behavioral control play a significant role in the decision process. The effect of an individual’s orientation toward nature is mediated by attitude and perceived behavioral control. It is important that these orientations are taken into consideration when designing strategies to increase incentives to mitigate fire risk. The second study explores the linkage between property owners’ perception of risk and scientifically measurable wildfire risks that vary across hazard zones in the three study locations. Individuals’ perceptions of wildfire can be substantially different from each other and from reality. This study proposes that the perception of risk is formed in a multistage process (individual and community level). Results show that homeowners’ worldview with respect to nature, length of residency, place-based influence, and attitudes about risk factors all are significant predictors for how residents of fire-prone areas perceive their risks. The variance in social and physical vulnerability associated with wildfire can explain, to a certain extent, the variation in individual perceptions of wildfire risk. The perception of risk is consistent with the level of exposure to fire hazards. The third study investigates spatial relationships among social and ecological factors on private property. The biophysical characteristics of individual properties were extracted to observe wildfire risk and incorporated with information about social context from mail surveys. Results demonstrate that mitigation behaviors in the three study communities illustrate a spatial clustering pattern. Moreover, orientations toward nature and physical attributes of property had an impact on decisions to undertake mitigation behaviors.