Browsing by Author "Hoffman, Chad, advisor"
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Item Open Access Advancing prescribed fire science through numerical simulation and improved reporting practices(Colorado State University. Libraries, 2022) Bonner, Sophie R., author; Hoffman, Chad, advisor; Linn, Rodman, committee member; Tinkham, Wade, committee member; Rocca, Monique, committee memberPlanning a prescribed burn that is safe and effective relies on land managers understanding how a complex suite of interactions between the burning environment (e.g., fuels, fire weather, and topography) and ignition factors influence fire behavior and effects. As the field of prescribed fire science has grown, more questions have arisen regarding how the spatial structure of forests and the ignition pattern affect the ecological outcomes of these burns. Advancing our understanding of these factors is crucial to provide managers with quality, evidence-based science that can inform prescribed fire planning. In this two-part thesis, my objectives were: i) to evaluate reporting quality in recent prescribed fire literature and suggest minimum reporting standards for future prescribed fire experiments, and ii) to explore the potential effects of complex forest fuel structures and ignition patterns on fire behavior and the resultant ecological effects during prescribed burns. In Chapter 1, I present results from a literature review of reporting standards from over 200 prescribed fire experiments conducted from 2016 to 2020. My results suggest substantial shortcomings in the reporting of critical data that limit the utility of prescribed fire research. Specifically, I found that specific information on burning conditions such as fuel moisture (22%), quantitative fuel loads (36%), fire weather (53%), and fire behavior (30%) were often not reported by the authors. Further, I found that only 54% of the studies provided descriptions of the ignition characteristics. Given these common deficiencies, suggested minimum reporting standards are proposed for future prescribed fire experiments which can be used to increase the quality, applicability, and reproducibility of prescribed fire science, facilitate future research syntheses, and foster actionable science. In Chapter 2, I evaluate how forest structural complexity and ignition pattern impact crown damage during simulated prescribed fires in longleaf pine (Pinus palustris) dominated forests of the southeastern United States. My results show that - regardless of forest structure – using a strip-head ignition pattern consistently produced more crown damage than spot-head or alternative spot-head ignition patterns. In terms of forest structure, I found forests with greater structural complexity resulted in more crown damage than less complex forests. More specifically, I observed forests with more aggregated horizontal spatial patterns, greater vertical complexity, and moderate to high amounts of canopy cover to produce more severe fire behavior than regularly spaced, single-story forests with sparse canopy cover. These findings suggest that managers need to consider a forest's structure and their choice of ignition pattern when planning prescribed burns to ensure they meet ecological objectives.Item Open Access Causes, consequences, and management of tree spatial patterns in fire-frequent forests(Colorado State University. Libraries, 2022) Ziegler, Justin Paul, author; Hoffman, Chad, advisor; Ocheltree, Troy, committee member; Redmond, Miranda, committee member; Rocca, Monique, committee memberIncreasingly, restoration treatments are being implemented to dually meet wildland fire hazard reduction alongside ecological objectives. Restoration treatments however deviate from conventional fuels treatments by emphasizing the re-creation of forest structure present prior to EuroAmerican settlement, notably the retention of single and grouped trees interspersed between canopy openings. As these historical forests persisted over cycles of fire returns, it is assumed that restoring these historical complex tree spatial patterns will, in turn, restore historical ecological processes. This includes more benign fire behavior that results in only partial tree mortality, allowing persistent and partial retention of forest cover over cycles of fire return. The qualitative description of historical forest structure, lacks, however, a clear process-based explanation detailing the interactions of heterogeneous forest structures and fire. While fires were historically frequent, it is unclear what role fire played in the genesis and maintenance of tree spatial patterns. If models of tree spatial dynamics can be improved and the interactions between tree spatial patterns and fire can be elucidated, forest managers will have an improved understanding of the implications of restoration-based fuels hazard reduction treatments both during fire-free periods and during fire events. The aims of this dissertation were to: 1) explore the causes of tree spatial patterns in dry fire-frequent forests; 2) investigate the consequences of tree spatial patterns on potential fire behavior and effects; 3) determine how alternate silvicultural strategies targeted at manipulation of tree spatial patterns can influence fire behavior and effects. In Chapter 2, I explored spatial patterns of tree regeneration over 44 years in absence of fire. In cooler periods, regeneration preferred clustering in openings, including openings following overstory mortality and away from overstory trees. Mortality risk of regeneration was heightened nearer overstory trees. In warmer periods, these trends reversed, likely because of a 'nurse effect' from the overstory. In anticipation of climate change, these results suggest silviculturists may benefit by capturing regeneration mortality in within openings while keeping regeneration near the overstory. In Chapter 3, I found that regenerating trees also form heterogeneous patterns following stand-replacing fires. In these sparse, early seral forests, all species were spatially aggregated, partly attributable to the influence of topography and beneficial interspecific attractions between ponderosa pine and other species. Results from this study suggest that scale-dependent, and often facilitatory, rather than competitive, processes act on regenerating trees. In Chapter 4, I studied the interaction between fire and tree spatial patterns, both historically and in modern forests. Tree mortality in the historical period was clustered and density-dependent because tree mortality was greater among small trees, which tended to be assembled in tightly spaced clusters. Tree mortality in the contemporary period was widespread, except for dispersed large trees, because most trees were a part of large, interconnected tree groups. Postfire tree patterns in the historical period, unlike the contemporary period, were within the historical range of variability found for the western United States. This divergence suggests that decades of forest dynamics without significant disturbances have altered the historical means of pyric pattern maintenance. In Chapter 5, I examined how fuels treatment designs with different manipulations of tree spatial patterns may influence treatment effectiveness. I simulated fires on hypothetical cuttings which manipulated the arrangement of crown fuels horizontally and vertically, either increasing the distance between tree crowns or not, and either removing small trees or not. All cutting methods reduced fire behavior and severity, but the results confirm possible tradeoffs between ecological restoration and hazard reduction; treatments that separated tree crowns reduced severity the most because these treatments reduced crown fire spread. But these can easily be overcome where restoration treatments incorporate small tree removal, because this action limits crown fire initiation. Managers could also incorporate managed fires to reduce surface fuel loads and use more aggressive cuttings to further gains in hazard reduction, regardless of cutting method used.Item Open Access Comparing crown fire predictions in ponderosa pine stands among four fire behavior models(Colorado State University. Libraries, 2024) Ney, Jacob, author; Hoffman, Chad, advisor; Linn, Rodman, committee member; Fischer, Emily, committee memberFire and land managers commonly use fire behavior modeling systems to support their planning and decision-making process. Fire modeling systems have been increasingly used across the western United States to plan fuel treatments that reduce hazard fuels, especially as a drier climate has resulted in more frequent high severity wildfire. Given differences in model types, approaches, assumptions, and sensitivity to various input parameters, modeling systems can produce different predictions and lead to different management decisions. Variability arising from model selection results in increased uncertainty within the decision-making framework. Multi-model comparisons help identify areas of model agreement and disagreement, reduce uncertainty associated with management decisions, and identify directions for future experimentation. Here, I compare predictions of fire type and crown fire rate of spread (ROS) among four modeling systems that represent a range of model types and complexities—Wildland-urban interface Fire Dynamics Simulator (WFDS), QUIC-Fire, a Rothermel-based modeling framework, and Crown Fire Initiation and Spread (CFIS). Comparisons (n = 297) were made based on a range of forest structure and environmental conditions representative of treated and untreated ponderosa pine forest stands in the southern Rocky Mountains. All four models predicted crown fire occurrence for 71% of simulations in total. WFDS, QUIC-Fire, and CFIS agreed on fire type more than 65% of the time. Rothermel predicted crown fire for 41% of simulations with ROS predictions 45% lower than the other models. Models tended to agree on crown fire occurrence in scenarios with a low canopy base height and greater surface and canopy fuel loading, indicating lower uncertainty in predicted fire behavior among models when fuel hazard is greatest. Differences among model predictions were more evident in scenarios with greater canopy base heights, moderate surface and canopy fuel levels, and at lower windspeeds. These results suggest that uncertainty introduced by model selection is likely greatest for designing and evaluation of fuel treatments, and that further research on fire behavior in treated forests stands is needed.Item Open Access Complex interactions between dwarf mistletoe, fuel loading, and fire in the lodgepole pine dominated forests of central Colorado(Colorado State University. Libraries, 2016) Ritter, Scott, author; Hoffman, Chad, advisor; Ex, Seth, committee member; Stewart, Jane, committee member; Zimmerman, Tom, committee memberLodgepole pine dwarf mistletoe (Arceuthobium americanum Nutt. ex Engelm) is an obligate hemiparsite that infects lodgepole pine (Pinus contorta Dougl. Ex. Loud) throughout the large majority of lodgepole pine’s range. Lodgepole pine dwarf mistletoe increases mortality rates, alters tree biomass distributions, and slows overall tree growth, which results in substantial losses to stand productivity and wood quality. In lodgepole pine dominated forests, dwarf mistletoe and wildfire are fundamental disturbances that may interact with each other in complex ways. This interaction is bidirectional as wildfire can either positively or negatively affect post-fire dwarf mistletoe populations, and pre-fire dwarf mistletoe populations may influence wildfire severity. Though it has long been assumed that dwarf mistletoe increases potential wildfire severity in lodgepole pine forests through modifications to the fuels complex, empirical data to support this conclusion is lacking. The overall goal of this project was to enhance the understanding of both sides of the fire-dwarf mistletoe interaction through a combination of long-term post-fire data, forest measurements, and simulation of dwarf mistletoe impacts and intensification. Chapter one provides background into dwarf mistletoe biology and pathology, and reviews the existing literature on interactions between fire and dwarf mistletoe. The second chapter documents the results of research into the influence of dwarf mistletoe infestation level on stand structure and fuel parameters that influence potential fire behavior. To evaluate the relationship between infestation severity and stand structure and forest fuels plots were randomly located within stands containing a range of dwarf mistletoe infestation severities. Of primary interest were impacts to canopy base height and the loading of fuels both on the forest floor and in the canopy. Chapter three is a case study documenting the impact of three prescribed crown fires on dwarf mistletoe populations thirty years post-fire. These fires burned across a range of mortality levels allowing for a detailed evaluation of the influence of fire severity on dwarf mistletoe populations. This chapter combines field measurements with forest growth and yield simulations from the United States Forest Service’s Forest Vegetation Simulator to understand longer-term impacts to both the dwarf mistletoe population and stand productivity. Field data from randomly located plots indicate that dwarf mistletoe may have conflicting impacts on parameters influencing crown fire potential and wildfire severity. This finding suggests that the impact of dwarf mistletoe infestation of potential wildfire severity may not conform to the positive linear relationship assumed by many forest pathologists. Infestation level was found to have a strong positive relationship with the loading of surface fuels of all sizes, and was negatively related to canopy base height, and calculated canopy fuel load and canopy bulk density. Impacts to stand structure include significant reductions to live basal area and average tree size, and significant increases to the density and basal area of standing dead trees. The results from the long-term post-fire data set provide experimental evidence showing that fire severity negatively influences future dwarf mistletoe populations, and that long-term population reductions are possible without complete stand replacement. Over multiple fire cycles, feedbacks between fire and dwarf mistletoe may enhance heterogeneity in burn patterns, infestation severity, and stand structures across the landscape.Item Open Access Horizontal and vertical forest complexity interact to influence potential fire behavior(Colorado State University. Libraries, 2022) Ritter, Scott Michael, author; Hoffman, Chad, advisor; Battaglia, Michael, committee member; Mell, William, committee member; Ex, Seth, committee member; Jathar, Shantanu, committee memberWildland fire behavior is a dynamic process controlled by complex interactions among fuels, weather, and topography. There is significant need to better understand the role of fuels and, particularly, complex arrangements of fuels, on potential fire behavior and effects as a there is a growing emphasis on forest treatments that emulate the heterogenous structures of historical forest ecosystems. Ideally such treatments are intended to reduce fire hazard while concurrently improving resilience to a wide range of disturbance agents and restoring the natural ecosystem dynamics that maintained these forest structures. One way to evaluate how the complex forest structures created by these treatments will influence fire behavior are modeling approaches that account for dynamic interactions between fire, fuels, and wind. These physical fire models build from computational fluid dynamics methods to include processes of heat transfer, vegetative fuel dehydration and pyrolysis, and gas phase ignition and combustion. In this work, several aspects of horizontal and vertical forest structure were evaluated to understand how spatial complexity influences fire behavior, with a particular emphasis on the transition of a surface fire into tree crowns. I used a combination of spatially explicit field data and a physics-based wildfire model, the Wildland-Urban Interface Fire Dynamics Simulator (WFDS), to deepen our fundamental understanding of fire behavior, inform the design of forest treatments that aim to achieve a variety of ecological and social objectives, and develop hypotheses related to the pattern-process feedbacks that contributed to the maintenance of resilient forests across millennia. Chapter 2 presents a simulation study focused on the relationship between horizontal forest structure and surface to crown heat transfer and crown fire initiation. The results indicated that relative to larger 7- and 19-tree groups, isolated individual trees and 3-tree groups had greater convective cooling and reduced canopy heat flux. Because isolated individuals and 3-tree groups were exposed to less thermal energy, they required a greater surface fireline intensity to initiate torching and had less crown consumption than trees within larger groups. Similarly, I found that increased crown separation distance between trees reduced the net heat flux leading to reduced ignition potential. These findings identify the potential physical mechanisms responsible for supporting the complex forest structures typical of high-frequency fire regimes and may be useful for managers designing fuel hazard reduction and ecological restoration treatments. Chapter 3 extends chapter 2 by investigating how different levels and types of vertical heterogeneity influence crown fire transition and canopy consumption within tree groups. These results show the importance of fuel stratum gap (or canopy base height) on vertical fire propagation, however vertical fire propagation was mediated by the level of horizontal connectivity in the upper crown layers. This suggests that the fuel stratum gap cannot fully characterize the torching hazard. The results also indicate that as the surface fire line intensity increases, the influence of horizontal connectivity on canopy consumption is amplified. At the scale of individual tree groups, the perceived hazard of small, understory trees and vertical fuel continuity may be offset by lower horizontal continuity (or canopy bulk density) within the midstory and overstory crown layers. Chapter 4 compares outcomes from four real-world forest treatments that cover a range of potential treatment approaches to evaluate their impacts of forest spatial pattern and potential fire behavior. My results indicate that restoration treatments created greater vertical and horizontal structural complexity than the fuel hazard reduction treatments but resulted in similar reductions to potential fire severity. However, the restoration treatments did increase the surface fire rate of spread which suggests some potential fire behavior tradeoffs among treatment approaches. Overall, these results suggest the utility of restoration treatments in achieving a wide range of management objectives, including fire hazard reduction, and that they can be used in concert with traditional fuel hazard reduction treatments to reduce landscape scale fire risk. Together this work shows that tree spatial pattern can significantly influence crown fire initiation and canopy consumption through alterations to net heat transfer and feedbacks among closely spaced trees. At the scale of the tree group these results suggest that larger tree groups may sustain higher levels of canopy consumption and mortality as they are easier to ignite and, in cases with small separation between crowns, can sustain horizontal spread resulting in density-depended crown damage. These findings carry over to vertically complex groups where the spatial relationship between small, understory trees and larger, overstory trees has a large impact on the ability of fire to be carried vertically. Further, in these vertically complex groups reducing the density (and/or increasing the horizontal separation) of the overstory trees, resulted in lower rates of crown fuel consumption, therefore, mitigating some of the "laddering" effect caused by the presence of small understory trees. These complex interactions between vertical and horizontal aspects of stand structure were born out in my evaluation of the measured forest treatments, where similar crown fire behavior reductions were observed across various stand structures. Overall, this work shows that forest managers can apply treatments to achieve a wide range of ecological benefits while simultaneously increasing fire resistance and resilience.Item Open Access Impacts of treatments on forest structure and fire behavior in dry western forests(Colorado State University. Libraries, 2014) Ziegler, Justin, author; Hoffman, Chad, advisor; Battaglia, Mike, committee member; Sibold, Jason, committee memberForest managers are increasingly using mechanical treatments in dry forests of the western US in order to produce stands with spatially complex structure while also reducing crown fire potential. However, there has been a lack of evaluation of these treatments on spatial patterns in dry forest types of the western US. In addition, the implications of heterogeneous fuels complexes on fire behavior are not well understood due to a lack of experimental data and the use of semi empirical models which cannot account for the structural complexity of fuel beds. The lack of well quantified studies on changes in spatial heterogeneity and limitations on quantifying the associated fire behavior suggest there are gaps in our knowledge regarding the implications of mechanical fuels treatments. The primary emphasis of this thesis is in Chapter 1. I comprehensively stem-mapped seven 4 ha plots, after treatment in dry, coniferous treated stands across the Southern Rockies and Colorado Plateau. Then, I estimated pre-treatment structure by constructing linear allometric regressions of tree characteristics and applying these to mapped stumps thus producing stem-maps before treatment. To investigate how these treatments altered structural complexity, I used spatial statistical analyses to assess spatial relationships of trees, before and after treatment, occurring at stand and within-stand scales as well as horizontal and vertical dimensions. Then, I assessed the cumulative effects of the reduction and spatial alterations of structure on potential fire behavior, measured by rate of spread, fireline intensity and percent of canopy consumed, across a range of open wind speeds using the Wildland urban-interface Dynamics Simulator (WFDS). WFDS is a physics-based model capable of representing the 3-D complexities of the fuels complex and captures fuel-atmosphere-fire dynamics through space and time. Results from this chapter suggest (1) treatments impact facets of structural complexity in varying ways, though avoided large-scale homogenization of forest structure, (2) within canopy wind speeds increase following treatments and, (3) fire behavior can be altered in two distinct manners following treatments. In most cases, the alterations in the fuels complex coupled with greater within canopy wind speeds resulted in an overall decrease in potential fire behavior and crown fire activity, especially at high open wind velocities. However, in two cases I examined there were increases in fire behavior following mechanical treatments. In these cases the increases were primarily associated with increased surface fire behavior. The results from this chapter suggest that these mechanical treatments may not always enhance, but can promote, a degree of structural complexity, and that mechanical treatments are effective if implemented strategically. Chapter 2 reports on litter bulk density values for use by managers to improve fuel loading assessments. Litter bulk density as a factor, in conjunction with litter depth, is used to estimate litter load necessary for fuel hazard assessments as litter is a primary carrier of fire and its load impacts potential rate of spread, fireline intensity and smoke production. In addition litter load estimation is needed for estimating carbon and wildlife habitat availability. However, available litter bulk density factors are limited by region, forest type, and site history. This chapter uses data collected on litter bulk density in both ponderosa (Pinus ponderosa Lawson) dominated and dry mixed conifer stands throughout the southern Rockies across sites that have been recently mechanically treated and in recently undisturbed sites. Results show litter bulk density was much lower in ponderosa pine forest than mixed conifer, and the impact of treatment was relatively negligible. These results provide managers in the southern Rockies with a regionalized value that may improve accuracy for estimation of litter load.Item Open Access Improving assessments of fuel treatment effects on surface fuels in ponderosa pine forests of the southern Rocky Mountains(Colorado State University. Libraries, 2015) Vakili, Emma, author; Hoffman, Chad, advisor; Dickinson, Yvette, committee member; Keane, Robert, committee member; Rocca, Monique, committee memberFuel hazard reduction treatments have been widely employed in dry forests of the western United States in recent decades in response to the increasing extent and severity of wildfires. In order to design and accurately assess the effects of these fuel hazard reduction treatments, accurate fuel inventories are required. However, obtaining accurate assessments of fuelbeds is complicated by a lack of knowledge about the effects of treatments on surface fuels and their spatial distribution. This thesis focuses on enhancing knowledge of treatment effects on surface fuels in ponderosa pine sites across Colorado and New Mexico, USA. The primary emphasis is on Chapter 1, which focuses on the spatial distribution of surface fuels and how it is changed by fuel hazard reduction treatments. I found that total surface fuel loads were reduced by ~10% in thinned sites and ~50% in thinned and burned sites. Semivariance following thin and burn treatments was similar to untreated sites and lower than thin-only sites for all fuel components except 1,000-hr fuels, with fuel component semivariance being highly predictable (R2=0.99) from fuel component mean fuel loading. The scale of spatial independence for all fuel components and sites ranged from <1-50 m with the shortest spatial scales occurring for the finest fuel components (i.e. duff, litter, etc.). Mean fuel particle diameter strongly predicted (R2=0.88) the distance needed to achieve sample independence. Incorporating such knowledge of spatial variability into fuel sampling protocols will enhance assessment of wildlife habitat and fire behavior and effects modeling over singular stand-level means. Chapter 2 focuses on the physical characteristics of fuel particles present before and after fuel hazard reduction treatments. I report mean squared diameter (d2) values for downed dead woody surface fuels that can be used to improve fuel loading assessments using the widely applied planar intersect sampling protocol. The planar intersect method requires an approximation of the mean squared diameter (d2) of 1, 10, and 100-hr timelag size classes to create loading estimates for downed dead woody surface fuels. I analyzed woody surface fuels collected throughout the southern Rocky Mountains to create local d2 estimates for untreated, mechanically treated, and mechanically treated and broadcast burned sites. Resulting estimates were up to 38% higher in the 1- and 10-hr classes and 28% lower in the 100-hr classes when compared to previously published values from other regions. The new burned partially harvested values for 1- and 100- hour classes were also roughly 20% lower than in the other stand conditions.Item Open Access Investigating the relationship between horizontal forest structure and fire behavior using a physics-based fire model(Colorado State University. Libraries, 2017) Burke, Conamara S., author; Hoffman, Chad, advisor; Mell, William, committee member; Amidon, Timothy, committee memberSilvicultural treatments are increasingly being implemented across the Western US in fire-prone forests as a way to simultaneously reduce fire hazard while also increasing horizontal structural heterogeneity (tree spatial patterns). However, it is poorly understood how fire behavior is impacted by treatment designs that incorporate tree clumping spatial configurations that mimic patterns found within the historic structural ranges of forests frequented by low to mixed severity fire. The Wildland Urban-Interface Fire Dynamics Simulator (WFDS), a physics-based fire behavior model, was used to better understand the effect that heterogeneous horizontal forest structure has on fire behavior. Fire behavior across seven treated ponderosa pine forests with different spatial patterns were simulated and compared to each other, and to an untreated scenario. All forest simulations were also burned under three different wind speeds and two surface fuel loading levels to better evaluate fuel treatment effectiveness across a range of conditions. Results indicate that the removal of surface fuels in treated stands was the most effective method for reducing the percent of canopy consumption and rates of fire spread, especially under high wind velocity conditions. This study found that variations in horizontal forest structure between treated forest scenarios had a minimal effect on driving differences in fire behavior, thus forest managers should be more concerned with increasing horizontal structural heterogeneity for ecological objectives rather than implementing such treatments to reduce the potential for hazardous fire behavior. Future research should focus on determining how vertical structural complexity interacts with horizontal structure to influence fire behavior.Item Open Access Mapping values at risk, assessing building loss and evaluating stakeholder expectations of wildfire mitigation in the wildland-urban interface(Colorado State University. Libraries, 2020) Caggiano, Michael, author; Hoffman, Chad, advisor; Amidon, Tim, committee member; Cheng, Antony S., committee member; Hawbaker, Todd, committee memberThe Wildland-Urban Interface (WUI) is an area where residential development extends into undeveloped land. When WUI development occurs in hazard-prone fire-adapted ecosystems, wildfires can have detrimental impacts on human communities by destroying buildings and infrastructure. Wildfires that cause substantial building loss are known as WUI disasters because of their high social and economic costs. WUI disasters tend to occur when wildfires ignite under extreme burning conditions and threaten a large number of homes in hazardous conditions relative to firefighting resources. This combination of factors can lead to significant home loss. WUI disasters annually result in billions of dollars in fire suppression costs and destroy thousands of homes Governments, land managers, and effected stakeholders respond to this threat in numerous ways as they attempt to mitigate the impacts of wildfires and reduce losses in WUI communities. Although wildfire mitigation efforts emphasize the removal of nearby flammable vegetation and the use of nonflammable building materials, one of the critical steps involves developing a map of communities and buildings at risk in the WUI. Despite broad-scale mapping efforts, most WUI maps do not identify building locations at sufficiently fine scales to estimate fire exposure and inform wildfire planning. Defensible space is promoted as the most effective way to reduce home ignition; however, questions remain surrounding its interactions with fire response, and its efficacy under the wide range of potential fire behavior to which homes could be exposed. This dissertation sought to realize three goals: first, it examined the potential of new technologies to map the WUI and the buildings within it at fine scales; second, it evaluated how well existing WUI mapping efforts capture the pattern of building loss observed during WUI disasters; and third, it examined stakeholder perspectives on the efficacy and interactions of defensible space and fire response with regards to protecting homes from WUI disasters. Chapter two evaluates the ability of Object Based Image Analysis to extract WUI building locations from orthoimagery of the wildland-urban interface by testing accuracy and error at multiple scales. I found the approach can extract building locations with high rates of accuracy, and minimal user input. Extracting building locations using this approach can lead to comprehensive datasets of building locations in the WUI, which can be used to create more detailed maps of buildings exposed to wildfires. Such maps have utility for risk mapping, fuel treatment prioritization, and incident management, and can lead to a better understanding regarding the spatial patterns of home loss. Chapter three leverages building location data to quantify the impacts of WUI disasters and evaluate the accuracy of WUI maps. I compare how well existing polygon-based SILVIS WUI maps and point-based WUI maps capture the pattern of building loss and assess building loss in relation to the core components of the WUI definition. Findings can be used to improve existing WUI maps, create point-based WUI maps from building location datasets, identify which homes are most in need of defensible space, and refine risk mapping and identification of wildfire exposure zones. Finally, chapter four assesses stakeholder perspectives regarding the efficacy of defensible space and its interactions with fire response with regards to the stakeholders' ability to protect homes from WUI disasters. This is related to the prior mapping efforts because it speaks to the ways stakeholders co-manage wildfire risk with fire protection authorities, and the actions they take to protect threatened homes mapped using the methods evaluated in chapters one and two. These qualitative methods suggest a wide range in expectations of defensible space efficacy, both in theory and in practice. It is likely that numerous factors reduce the perceived and actual efficacy of defensible space.Item Open Access Simulating cut to length forest treatment effects on fire behavior over steep slopes(Colorado State University. Libraries, 2023) Pittman, Kyle Tait, author; Jathar, Shantanu, advisor; Hoffman, Chad, advisor; Linn, Rod, committee member; Windom, Bret, committee member; Wei, Yu, committee memberThe increase of wildfire size and behavior in many western U.S. forests is due to increased fuel loads resulting from the past century's fire suppression, logging, and grazing policies of the 20th century, along with compounding climactic changes including increased drought and temperatures. Fuel hazard treatments are the key land management tool used to reduce fire intensity and severity however these treatments are often not possible on steep terrain of over 30% slope. Cable tethered cut to length machinery opens new avenues for managers to treat forests in steep slopes, but there is limited data on how effective the treatments will be. I conducted a numerical experiment using the wildfire model, FIRETEC, coupled with the atmospheric dynamics model, HIGRAD, to understand the complex interactions of wind, topography, and fire behaviors of two cut to length forest treatments on slopes of up to 60%. Results show that treatments can effectively reduce some fire behaviors such as heat release and canopy consumption when compared to untreated forests on slopes. However, increased sub canopy wind penetration along the slopes following treatments results in marginal fire severity reduction regarding biomass consumption and variable results on rates of spread. The results of these numerical experiments indicate that CTL treatment can effectively reduce some fire behavior and severity, however the effects were marginal and additional research is needed to better understand treatment's effects.