Browsing by Author "Hoffman, Chad, committee member"
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Item Open Access Analyzing risk-related information seeking behavioral intention and risk perception of wildfires: the High Park Fire Burn Area(Colorado State University. Libraries, 2019) Mokry, Melissa M., author; Trumbo, Craig, advisor; Kim, Jangyul, committee member; Abrams, Katie, committee member; Hoffman, Chad, committee member; Schumacher, Russ, committee memberThis study assessed risk-related information seeking behavioral intention and dual-process risk perception within the context of wildfires. Particularly, the study focused on utilizing a combined risk-related information seeking model with concepts originating from the planned risk information seeking model (PRISM), a framework of risk information seeking (FRIS), and the risk information seeking and processing model (RISP). The key concepts utilized included: past risk-related information seeking, self-efficacy, response efficacy, dual-process risk perception (affective and cognitive risk perception, perceived hazard knowledge, information needs, and behavioral intention. A survey (N=432; 60.8% response rate) was disseminated to the High Park Fire Burn Area, west of Fort Collins, Colorado which experienced a wildfire in 2012. The survey revealed the importance of including dual-process risk perception in risk-related information seeking models and highlighted its influence on past risk-related information seeking and risk-related information seeking behavioral intention. Response efficacy was correlated with self-efficacy, following suit to other risk-related information seeking studies. Cognitive risk perception was correlated with affective risk perception, suggesting a bi-directional relationship between the two concepts. Individuals were more likely to seek wildfire information in the past if they did not have enough knowledge about the hazard. Moreover, individuals are more likely to base their risk perception on their emotions, particularly when facing a wildfire. The results from the survey revealed that the exploratory path had a better model fit than the confirmatory path model, yet both provided important findings related to risk-related information seeking behavioral intention and dual-process risk perception. This study reaffirmed the need for theoretical improvement related to current information needs, particularly in relation with perceived hazard knowledge and risk-related information seeking behavioral intention. There were inconsistencies with current information needs throughout the study, following suit with the literature and calls for further refinement of the concept. Implications and future research efforts are also noted and discussed such as the importance of tailored messaging and a communication campaign.Item Open Access Building capacity and integrating training, education and experience: the Fire Learning Network's Prescribed Burn Training Exchanges(Colorado State University. Libraries, 2014) Spencer, Andrew G., author; Schultz, Courtney, advisor; Hoffman, Chad, committee member; Kaiser, Leann, committee memberPrescribed fire is an important tool for forest and rangeland management, but there are barriers to its use, including a lack of qualified personnel with the necessary ecological knowledge and operational expertise. In order to implement prescribed fire across landscapes containing a variety of ownerships, these personnel should be from both federal agencies and non-federal organizations. Further, fire science educators have suggested that in order to prepare the next generation of fire professionals, three components--training, education, and experience--must be integrated in a professional development triangle. However, recognized needs for professional development and increased use of fire are not being met. The Prescribed Burn Training Exchange model from the Fire Learning Network incorporates the three components of the professional development triangle while fostering collaboration between nongovernmental organizations, private contractors, landowners, and government agencies. This study evaluated the training model and assessed outcomes using surveys, interviews, focus groups, and participant observation. I found that the participants are very satisfied with the flexible model across disparate training needs and experience levels. The results suggest that the training model is a valuable addition to prescribed fire education opportunities, can be implemented by other organizations, and therefore can serve to increase the capacity for fire management.Item Open Access Conifer regeneration and fuels treatment longevity in dry mixed-conifer forests of the Colorado Front Range(Colorado State University. Libraries, 2018) Fialko, Katie, author; Ex, Seth, advisor; Fornwalt, Paula, committee member; Hoffman, Chad, committee member; Rocca, Monique, committee memberThroughout much of the western United States, wildfires have been increasing in size and severity. To prevent negative impacts to communities and ecosystems, costly fuels reduction treatments are being applied to dry, mixed-conifer forests in Colorado and throughout the southern Rockies. The objective of this project was to make inferences about treatment longevity by determining how site, treatment, and vegetation characteristics of treated areas influence the abundance and composition of conifer regeneration, which can serve as fuels to initiate a high severity wildfire. Thinning and mastication treatments ranging in age from 5-14 years old on north and south aspects were examined. Time since treatment and residual overstory density and composition, along with aspect, had the greatest influence on the abundance of Douglas-fir and ponderosa pine regeneration in fuels treatments. Conifer regeneration did not vary by mastication vs thinning treatment type. Although Douglas-fir advance regeneration abundance decreased over time since treatment, it comprised 50% of all regeneration observed. This is a concern because advance regeneration will reduce treatment longevity more than the gradual accumulation of post treatment seedlings, and because it has the potential to release. Post treatment Douglas-fir regeneration was positively related to Douglas-fir residual overstory density but had no relationship with time since treatment. Post treatment ponderosa pine regeneration, however, increased with time since treatment and was negatively related to total residual overstory density. These findings indicate that while Douglas-fir regeneration may belimited by the lack of residual Douglas-fir in the overstory to provide a seed source, treatments are effectively acting as shelterwood regeneration treatments to increase the abundance of ponderosa pine. Lastly, average abundance of all conifer regeneration was five times greater on north aspects than on south aspects. Forest managers implementing future fuels reduction treatments, or planning the re-treatment of existing units, should monitor advance regeneration for potential release, anticipate a greater post treatment regeneration response on north aspects, and possibly expect a shift in future stand composition towards ponderosa pine.Item Open Access Develop a multi-periods fuel treatments allocation model to fragment landscape high hazard fuel patches(Colorado State University. Libraries, 2013) Suksavate, Warong, author; Wei, Yu, advisor; Hoffman, Chad, committee member; Kling, Robert, committee memberIncreased forest fuel loading and continuity have led to more large fires that can potentially cause the loss of property, life and forest resources in certain forest ecosystems. Strategically fragmenting landscape fuel patches with the potential of carrying high intensity or crown fires helps mitigate the future fire risks. This research develops a mathematic integer programming model to optimally locate fuel treatment locations across a landscape for multiple decades. Solutions are aimed at strategically fragmenting high fire hazard fuel patches that support high intensity fires or crown fires. This model can be used to schedule treatments in each stand by reacting to fire ignition probability, potential fire damages to wildland urban interface (WUI), streams, lakes, and the cost of fuel treatment. A set of prototype test cases based on artificial data are used to demonstrate the model performance and support preliminary analyses. This theoretical model can be extended to study a variety of fuel treatment related management concerns across space and time when realistic data become available.Item Open Access Dynamics of stress and mortality for grass dominated ecosystems: an interplay of water limitation, heat, and erosion(Colorado State University. Libraries, 2024) Bradfield, Scott J., author; Ocheltree, Troy, advisor; Knapp, Alan, committee member; Augustine, David, committee member; Hoffman, Chad, committee memberGrass dominated systems account for ~40% of the earth's terrestrial surface and typically occur in semi-arid and arid regions. The plant species that grow in these systems are known for their ability to withstand disturbance, including drought, grazing, and fire. While it is understood that the plants in these systems often experience multiple forms of stress in a growing season, interactions among these stress variables are not well represented in the literature. In this research, I sought to determine how combinations of stress variables influence the shortgrass steppe, this includes: long-term grazing, drought, erosion, and temperature. Specifically, I examined (1) how the interaction of long-term grazing and drought influences the recovery of the vegetation on the SGS following single-year and multi-year droughts, (2) how the interaction of grazing and erosion influence mortality following exposure to extreme surface temperatures, and (3) performed a comparative analysis of the microclimate of grass dominated systems in the United States to determine the intensity and frequency of stressful abiotic conditions that the vegetation experiences. First, I quantified the interactive effects of single and multi-year droughts with grazing pressure, because the Bouteloua species that dominate the region have been shown to be tolerant of grazing and drought independently, but the interactive effects of the two have not been well studied. Past research has focused on heavy cattle grazing but I included a mixture of moderate cattle grazing with prairie dogs, which is more intensive grazing than heavy cattle grazing. I found that the combined stress of multiple years of drought along with high grazing pressure has the potential to increase mortality in these Bouteloua species. Next, I quantified the erosion severity by ranking the amount crown exposure of the Bouteloua species during a drought on the SGS and then determined how erosion influenced bud outgrowth (production of a tiller) during the recovery year. I combined these data with environmental data collected by the National Ecological Organization Network (NEON) to determine the environmental conditions that the meristems of the plants experienced during the drought. My results showed that the temperatures at the surface of the soil, and exposed meristems, frequently reached levels thought to be lethal to plant cells. I acknowledge that it was likely a combination of water deficit and temperature that led to mortality of Bouteloua species that experienced erosion, but the high temperatures alone had the capacity to cause mortality of the meristems. Finally, I compared several near surface micrometeorological variables of grass dominated systems across the United States. Ultimately, I wanted to determine the frequency that these systems experienced temperatures near the surface that would be damaging to plants, if conventional methods for determining heatwaves represents damaging conditions to grassland plants, and what environmental factors lead to potentially damaging surface temperatures. I found that damaging temperatures occur often at arid sites, conventional heatwaves overestimate heat stress in sites that are wet or at higher latitudes, and underestimates heat stress for arid sites.Item Open Access Firefighter observations on mountain pine beetle post-outbreak lodgepole pine fires: expectations, surprises and decision-making(Colorado State University. Libraries, 2014) Moriarty, Kevin, author; Cheng, Antony S., advisor; Hoffman, Chad, committee member; Cottrell, Stuart, committee memberRecent wildfires in mountain pine beetle (Dendrocronas ponderosae; MPB) post-outbreak lodgepole (pinus contorta var. latifolia) stands in the western United States have generated concern among stakeholders and disagreement over predicted fire behavior in the scientific literature. A study was conducted of wildland firefighters' observations of fire behavior in beetle-killed lodgepole pine forests to garner a better understanding of expected vs. observed fire behavior, with a focus on what fire behaviors surprised firefighters. Twelve MPB post-outbreak wildfires and one prescribed fire were identified in northern Colorado and southern Wyoming using USDA aerial surveys, USGS MODIS based perimeter mapping and local knowledge. Twenty-eight wildland firefighter interviews were conducted among 7 different federal, state, county, local and non-profit agencies with a total of 55 observations. Expectations, observations, surprising fire behavior and tactical decisions were categorized using qualitative coding and interpretation. Expectations were greatly based on prior wildland fire experiences rather than the scientific research results. Surprising fire behavior in the red phase included increased fire behavior in moderate conditions, increased spotting, faster crown fire transition and crown fire transition with limited or no ladder fuels. Surprising fire behavior in the grey phase included crown ignition and crown fire propagation. Observations support the increased fire behavior in MPB post-outbreak red phase and diverge from studies predicting reduced crown fire potential in red and mixed phases. Firefighters formed new expectations of active fire behavior potential in all weather conditions and MPB phases. However, respondents concluded that specific conditions of fuel, weather and topography are the main driving forces in fire behavior and MPB influence was limited to distinct events. Firefighters changed tactics by taking more indirect suppression approaches due to fire behavior and tree hazard.Item Open Access Fuel treatment longevity in a dry mixed conifer forest on the Colorado Front Range(Colorado State University. Libraries, 2017) Francis, David, author; Ex, Seth, advisor; Hoffman, Chad, committee member; Martin, Patrick, committee memberHazardous fuel treatments have been occurring on an increasingly large scale throughout the western US in response to uncharacteristically severe wildfires in recent decades. These treatments have been shown to be effective in the short term but how long they remain effective, and the factors that affect this, is less clear. As these treatments are often very expensive to implement, knowing when a treated unit will return to pre-treatment fire risk is of critical importance for prioritization of sites and long-term forest planning. The majority of these treatments have occurred in dry mixed conifer forests as they have been the most affected by fire suppression policies, allowing fuels to accumulate and create high fire risk potential, and are often close to human settlement. We examined treatments that used thinning with and without follow-up prescribed fire in mixed stands of ponderosa pine and Douglas-fir. These treatments were examined on north and south aspects at times from 3-12 years after treatment. As hypothesized, we found conifer seedlings densities increased with time since treatment. Our data suggest a density of 500 seedlings ha-1 could be observed on southern aspects 10 years post-treatment. North aspects had twice the seedling density of south aspects at 10 years post-treatment, driven by the presence of Douglas-fir. Ponderosa pine seedling density was found to increase as a result of treatment, with the regeneration rate not being significantly affected by aspect or treatment type. In contrast, Douglas-fir regeneration was not promoted through treatment but was most correlated to the amount of Douglas-fir overstory basal area and found mainly on north aspects. We also found that neither fine or coarse surface fuels nor litter or duff depths had begun showing a significant increasing trend a decade after treatment. Conifer regeneration is diminishing the treatment effectiveness within a decade of treatment and will require retreatment in the future to reduce severe fire potential. While ponderosa pine regeneration can be expected to increase as treatments create more favorable establishment conditions, Douglas-fir regeneration can be expected to be higher when more Douglas-fir is left in a stand during treatment. Advance regeneration was also found to comprise a considerable portion of encountered seedlings and should be removed during treatment to increase treatment longevity.Item Open Access Lodgepole pine regeneration after mountain pine beetle and wildfire: a case study in the High Park Fire, CO(Colorado State University. Libraries, 2016) Wright, Micah, author; Rocca, Monique, advisor; Rhoades, Charles, committee member; Hoffman, Chad, committee memberThe 2012 High Park Fire burned over 35,000 hectares, including 5,000 hectares of lodgepole pine (Pinus contorta) forest that had recently been attacked by mountain pine beetle (MPB, Dendroctonus ponderosae). This sequence of events provided an excellent opportunity to investigate the effects of combined disturbance on lodgepole pine regeneration trajectories. I examined the influence of MPB mortality, high canopy fire severity, site characteristics, and post fire mulching treatments on lodgepole pine recovery at both landscape (∼hectare) and fine (∼cm) spatial scales. At the landscape scale, lodgepole pine seedling densities varied from 240 to 470,000 stems/ha. Seedling densities decreased as MPB mortality and high canopy fire severity increased. At the fine scale, lodgepole pine seedling establishment was positively related to local cone abundance and negatively related to high canopy fire severity. Topographic variables such as aspect and elevation did not have a strong influence on seedling density or establishment at either scale, nor did competition from recovering vegetation have an influence at the fine scale where it was considered. In areas with high canopy fire severity, post-fire straw mulching treatments were positively related to seedling establishment, indicating that mulching treatments may have additional benefits beyond erosion control. My research demonstrates that combinations of pre-fire mountain pine beetle mortality and high canopy fire severity can affect lodgepole pine regeneration, and may drive heterogeneity in the post-fire landscape.Item Open Access Survival of the fittest: an examination of the High Park fire news meme lifecycle on news organizations' Facebook and web pages(Colorado State University. Libraries, 2013) Shugarts, Angela, author; Switzer, Jamie, advisor; Seel, Pete, committee member; Hoffman, Chad, committee memberThis study employs a mixed methods content analysis of 14 news organization's Facebook and website posts of the High Park fire news meme to identify the reasons behind how and why news memes propagate within social media and news website environments. This study gauges the feasibility of forecasting the spread of online news content based on specific features including photos, videos, article length, and span of time. News memes are defined as cultural units of information presented as written text, images, or videos whose existence is determined by the frequent behaviors of imitation and transmission, produced by media personnel from news organizations. The field of memetics, social media, and normative theories of the media serve as foundational areas for this study which extends the knowledge of the emerging domain of web memetics, which seeks to identify and track the evolution, spread, and implications of news memes by media personnel. Results show that specific characteristics (i.e. text, links, and photos) contributed to news meme propagation via reader comment contributions and likes. Additionally, results indicate that website environments are more frequent platforms for news memes to exist and thus perhaps more nurturing environments for High Park fire news memes to propagate within.Item Open Access The ecological effects of multiple disturbances on subalpine forest structure and recovery in a changing climate(Colorado State University. Libraries, 2020) Schapira, Zoe, author; Stevens-Rumann, Camille, advisor; Hoffman, Chad, committee member; Rocca, Monique, committee memberDue to the shifting global climate, the severity, size, and frequency of climate-driven disturbances are increasing, inevitably causing disturbances to interact in time and space. Bark beetle epidemics and wildfires have historically shaped the disturbance regimes of western North American forests. Their interactive effects on stand dynamics and recovery are inadequately studied in Engelmann spruce (Picea engelmannii)- subalpine fir (Abies lasiocarpa) dominant forests; understanding these interactions is imperative to the management and health of forested ecosystems. Tree seedling densities and species composition, surface fuel loading, and stand structure characteristics were compared across 80 sites that experienced either high tree mortality from epidemic spruce beetle outbreaks (>50% affected basal area), high-severity wildfire (>90% tree mortality), post-outbreak high-severity wildfire (1-3 years post-outbreak), or no disturbance (control) in northern Colorado and southern Wyoming. The beetle-affected sites span multiple years post-outbreak from 1996-2017, ultimately comprising a chronosequence of beetle-affected stands. Structural changes in subalpine stands following spruce beetle outbreaks include species compositional shifts in overstory trees, and significant increases in fuel loading over time-since-outbreak. Tree seedling densities among outbreak and control sites differ significantly from burned areas, indicating that wildfires override the effects of repeated disturbances on regeneration. While a cursory assessment of post-outbreak regeneration based on height resulted in the appearance of consistent and stable forest recovery, subsequent aging techniques shed additional light on the drivers of subalpine tree establishment. Subalpine tree regeneration may remain suppressed in the understory for over a century; post-outbreak recovery dynamics cannot be fully understood through the use of height as a proxy for seedling age. Given the strong correlation between Engelmann spruce and subalpine fir establishment with cool and moist growing conditions, there remains significant uncertainty about post-disturbance recovery and the persistence of spruce-fir forests in a warming and drying world. It is critical to understand post-disturbance fuel dynamics and stand recovery to identify hazards for subsequent fire suppression, implement treatments to enhance forest resilience, and to understand the potential consequences of climate-induced shifts in disturbance regimes on forest health.Item Open Access Unmanned aerial systems for forest structure mapping: assessments of area-based and individual tree monitoring(Colorado State University. Libraries, 2020) Creasy, Matthew, author; Tinkham, Wade T., advisor; Vogeler, Jody, committee member; Hoffman, Chad, committee memberCharacterization of forest structure is important for management-related decision making, especially in the wake of disturbance. Increasingly, observations of forest structure are needed at both finer resolution and across greater extents in order to support managers in meeting spatially explicit objectives. Current methods of acquiring forest measurements can be limited by a combination of time, expense, and either extent or temporal resolution. Drone or UAS-based photogrammetry provides an airborne method of forest structure data acquisition at a significantly lower cost and time commitment when compared to existing methods of such as airborne laser scanning (LiDAR). A growing body of literature confirms UAS-based photogrammetry models can be as detailed as conventional LiDAR models. However, there exists a knowledge gap in best practice for data acquisition parameters and assessment of accurate characterization within forest photogrammetry. The following two chapters utilize large stem mapped sites to fill that knowledge gap by 1) systematically testing the effects of UAS flight speed and altitude on plot-based aboveground biomass modeling through photogrammetry and 2) evaluating several algorithms for detecting individual tree locations and characterizing crown areas. Results show a strong positive relationship between flight altitude and aboveground biomass modeling, with all UAS flights evaluated above 80 m altitude, providing better results (2-24% more variance explained) than contemporary LiDAR modeling strategies. Additionally, results demonstrate that the probability of detecting individual trees decays moving from the dominant overstory to suppressed trees, corresponding to >97% at the top of the canopy and decreasing to 67% for trees in the understory. Our results indicate the potential for UAS photogrammetry to produce highly detailed maps of forest biomass, as well as capture variation of forest structure through the detection of trees and tree groups. Such high-resolution data has the potential to become a much-needed tool for monitoring forest structures to inform spatially explicit management objectives. Additionally, these studies reinforced how UAS photogrammetry can provide low-cost repeat monitoring of forest conditions.