Climate change is causing increases in the frequency, severity, and extent of fires in the boreal forest, which in turn is expected to change historical cycles of permafrost response and recovery to disturbance. A review of recent literature (forming part of this thesis) shows that there are disparities in current knowledge of post-fire permafrost response. First, the majority of studies on permafrost-fire interactions have been conducted in Alaska, leaving regional gaps for the boreal forest across Canada. Second, there are limited direct measurements of certain variables which affect post-fire permafrost dynamics. These include snow depth, burn severity, and soil moisture, as well as ground ice content and quantified subsidence and thermokarst development. Third, the majority of post-fire permafrost studies address near-surface impacts, neglecting permafrost conditions at depth. Finally, there is a lack of long-term information and regional investigations over a broad range of environmental conditions, particularly how permafrost responds across a variety of ground ice contents. This thesis addresses these knowledge gaps through in-situ measurements and analysis of permafrost conditions following fires occurring over the last half century and in particular in 2014 and 2015, along a 650 km latitudinal transect spanning the discontinuous zones, from isolated patches (57.8°N) to extensive discontinuous permafrost (63.1°N), in northwest Canada. A variety of monitoring techniques were used to evaluate permafrost change, including ground and air temperature measurements, direct current electrical resistivity tomography (ERT) surveys, measurements of frost table depth, snow depth, organic layer thickness, burn severity, and ground subsidence. Samples of frozen and unfrozen soil were collected by coring or pit digging, and laboratory analyses conducted to establish soil characteristics. Laboratory experiments were also performed to establish a relationship between resistivity and temperature, and to generate a threshold between frozen and unfrozen soil that could assist in the interpretation of ERT surveys. A total of 68 sites along the Mackenzie Highway in northern Alberta and southern Northwest Territories (NWT) were examined to evaluate permafrost change due to climate warming and forest fire since an initial survey in 1962. The transect extends through the isolated patches and sporadic discontinuous permafrost zones, including 11 sites which burned at various times between 1971 and 2012. Overall, there has been significant permafrost degradation, especially at sites with thin organic layers and coarse-grained soils. This occurred preferentially at the southern end of the transect, where nearly 2°C of climate warming has occurred, such that even undisturbed sites experienced degradation. However, permafrost has persisted at about half of the sites where black spruce (Picea mariana) canopies with organic layers generally >40 cm thick overlie fine-grained sediments. Permafrost even persisted at the majority of burned sites, but greater frost table depths were observed at those which were burned in 2012. A second transect was established to examine permafrost change following the abnormally severe fire year of 2014 (and more limited fires in 2015) that affected sites across a wide range of conditions in the southern NWT. Eleven monitoring sites were established in the sporadic and extensive discontinuous zones between 2015 and 2016, and annual field surveys were conducted through to 2019, including the first repeat ERT surveys conducted following fire. Permafrost change occurred at all sites, including unburned ones, indicating the ongoing impacts of climate change in the region. Snow-depth days, maximum snow depth, and the nival offset were all greater at burned sites. Permafrost change was more pronounced at burned sites, with greater relative decreases in average apparent resistivity and increases in frost table depths and ground temperatures, particularly at sites with low gravimetric moisture content, coarse soil textures, and organic layers <40 cm thick. These changes are pronounced in the near surface (<5 m depth), with deeper permafrost appearing relatively unaffected within the 5-year post-fire time-frame. The field observations indicate that permafrost can still persist following fire at a significant percentage of locations in the discontinuous zone. However, slow degradation is occurring at both burned and unburned sites due to the warming climate, and particularly at dry sites with coarse-grained soils and thin organic layers. Post-fire permafrost change is evident at sites which burned in the last 10 years, but over the long-term, frozen ground appears resilient to fire, with characteristics like active layer thickness returning to pre-fire levels. Similarly, cold permafrost on the taiga shield is resilient to fire, even with thin residual organic layers. At high ice-content sites, however, where ground subsidence and thermokarst develop, water inundation and permafrost thaw can occur, particularly in areas which have been severely burned. This thesis underlines, therefore, the importance of monitoring and modelling a variety of landscape types to establish post-fire permafrost impacts and temperature trajectory, and more specifically the effects of heterogeneity of drainage conditions, substrate, and organic layer thicknesses on the fate of permafrost in the boreal forest.

The human risk as a spatial component using Newton?s Gravity model is explored for the first time in this research along with fuels and road density variables to predict the fire occurrences for Southeast Mississippi fire district. The fire risk map indicated that fires occur in clusters and are dependent on fire size and distance from roads. The results proved that fire size increases as fire locations increase. Fire locations decrease significantly beyond 160 meters with increasing road distance. The Gravity model proved to be a better estimator of fire risk while a similar road density model proved to be better in very low and medium fire risk zones. Compared to road density, the gravity model significantly proved a better estimate of very low fire risk for all seasons and summer low fire risk. For all other fire risks, though, gravity model showed better results no significant differences were observed.

A novel approach for modeling anthropogenically-initiated wildfire ignition was developed that significantly advances the theoretical knowledge of human-wildfire interactions. Gravity interaction models that are commonly used for economic analyses associated with business competition were combined with fluid dynamics models that mimic human movement patterns to predict the probability of anthropogenically-initiated wildfire. Herein, a combined gravity interaction and fluid dynamics models is developed and validated for wildfire potential prediction against historic and current wildfire data. The study identified population centers and transportation corridors, in particular: proximity to railroads and roads; traffic volume; and density of the corridors as the most influential factors for wildfire ignition. The population centers are identified as global influencing factors, and are modeled as the gravity term. The transportation corridors are identified as local influencing factors, and are modeled using fluid flow analogy as diffusion and convection terms. An analytic convection diffusion model (CDM) model is derived and the model coefficients calibrated using historic wildfire data. The model is implemented in GIS, and applied for the prediction of wildfire potential prediction in southeastern Mississippi. The model shows a correlation of R2=0.87 against winter historic data, whereas the Gravity model with a fuel component shows only R2=0.75 correlations. The improved predictions using the proposed CDM model is due to its capability to predict both the global and the local measure of incendiary activity patterns within a single dynamic equation. The CDM model can be used as a standalone model that can predict the wildfire potential in a region. It can also be combined with the fuel layer and meteorological conditions to obtain spatio-temporal variation of wildfire risks, which would provide a decision support system for wildfire mitigation and land use planning and development. The CDM model will help fire managers better plan wildfire mitigation (fuel reduction) strategies and effectively stage equipment and personnel geographically in areas of drought that are coincident with high ignition probability. Land use and transportation managers will gain better understanding of the changes in wildfire risk pattern due to urban fringe development.

For two fire seasons in Nordegg, Alberta, a system of in-stand weather stations were arranged along a north and south aligned valley and combined with collection of destructive fine fuel moisture content data in order to quantify variations due to differences in slope and aspect. South-facing sites were found to be slightly warmer (1.5°C), less humid (5%) and received on average 20% more solar radiation than the north-facing sites during the peak burning period of the day. Based on these weather observations a difference of 1 or 2 % moisture content between north and south sites was predicted using existing theoretical relationships. A corresponding difference in observed moisture content was not identified, due to the low transmittance recorded at the in-stand sites (<10% of open solar radiation measurements), variation amongst destructive samples and logistical limits on the number of replicates collected.

For two fire seasons in Nordegg, Alberta, a system of in-stand weather stations were arranged along a north and south aligned valley and combined with collection of destructive fine fuel moisture content data in order to quantify variations due to differences in slope and aspect. South-facing sites were found to be slightly warmer (1.5°C), less humid (5%) and received on average 20% more solar radiation than the north-facing sites during the peak burning period of the day. Based on these weather observations a difference of 1 or 2 % moisture content between north and south sites was predicted using existing theoretical relationships. A corresponding difference in observed moisture content was not identified, due to the low transmittance recorded at the in-stand sites (<10% of open solar radiation measurements), variation amongst destructive samples and logistical limits on the number of replicates collected.

abstract: C.C. Cragin Reservoir’s location in the Coconino National Forest, Arizona makes it prone to wild fire. This study focused on the potential impacts of such a wild fire on the reservoir’s annual thermal stratification cycle impacts and water quality. The annual thermal stratification cycle impacted the reservoir’s water quality by increasing hypolimnion concentrations of magnesium, iron, turbidity, and specific ultraviolet absorbance (SUVA) values, as well as resulting in the hypolimnion having decreased dissolved oxygen concentrations during stratified months. The scarification process did not affect the dissolved organic carbon (DOC) concentrations in the reservoir or the total/dissolved nitrogen and phosphorous concentrations. Some general water quality trends that emerged were that phosphorous was the limiting nutrient, secchi disk depth and chlorophyll a concentration are inversely related, and no metals were found to be in concentrations that would violate an EPA drinking water maximum contaminant level (MCL). A carbon mass model was developed and parameterized using DOC measurements, and then using historic reservoir storage and weather data, the model simulated DOC concentrations in the reservoir following four hypothetical wild fire events. The model simulated varying initial reservoir storage volumes, initial flush volumes, and flush DOC concentrations, resulting in reservoir DOC concentrations varying from 17.41 mg/L to 8.82 mg/L. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

The forests of south-eastern Australia, having evolved in one of the most fire-prone environments in the world, are characterized by many adaptations to recovery following burning. Thus forest ecosystems are characterized by rapid regenerative capacity, from either seed or re-sprouting, and mechanisms to recover nutrients volatilized, including an abundance of N2 fixing plants in natural assemblages. Soil physical, chemical and biological properties are directly altered during fire due to heating and oxidation of soil organic matter, and after fire due to changes in heat, light and moisture inputs. In natural ecosystems, carbon (C) and nitrogen (N) lost from soil due to fires are recovered through photosynthesis and biological N2 fixation (BNF) by regenerating vegetation and soil microbes. / This study investigated post-fire recovery of soil C and N in four structurally different sub-alpine plant communities (grassland, heathland, Snowgum and Alpine ash) of south-eastern Australia which were extensively burnt by landscape-scale fires in 2003. The amount and isotopic concentration of C and N in soils to a depth of 20 cm from Alpine ash forest were assessed five years after fire in 2008 and results were integrated with measurements taken immediately prior to burning (2002) and annually afterwards. / Because the historical data set, comprised of three soil samplings over the years 2002 to 2005, consisted of soil total C and N values which were determined as an adjunct to 13C and 15N isotopic studies, it was necessary to establish the accuracy of these IRMS-derived measurements prior to further analysis of the dataset. Two well-established and robust methods for determining soil C (total C by LECO and oxidizable C by the Walkley-Black method) were compared with the IRMS total C measurement in a one-off sampling to establish equivalence prior to assembling a time-course change in soil C from immediately pre-fire to five years post-fire. The LECO and IRMS dry combustion measurements were essentially the same (r2 >0.99), while soil oxidizable C recovery by the Walkley-Black method (wet digestion) was 68% compared to the LECO/IRMS measurements of total C. Thus the total C measurement derived from the much smaller sample size (approximately 15 mg) combusted during IRMS are equivalent to LECO measurement which require about 150 mg of sample. / Both total C and N in the soil of Alpine ash forests were significantly higher than soils from Snowgum, heathland and grassland communities. The ratio of soil NH4+ to NO3- concentration was greater for Alpine ash forest and Snow gum woodland but both N-fractions were similar for heathland and grassland soils. The abundance of soil 15N and 13C was significantly depleted in Alpine ash but both isotopes were enriched in the heathland compared to the other ecosystems. Abundance of both 15N and 13C increased with soil depth. / The natural abundance of 15N and 13C in the foliage of a subset of non-N2 fixing and N2 fixing plants was measured as a guide to estimate BNF inputs. Foliage N concentration was significantly greater in N2 fixers than non-N2 fixers while C content and 13C abundance were similar in both functional groups. Abundance of 15N was depleted in the N2 fixing species but was not significantly different from the non-N2 fixers to confidently calculate BNF inputs based on the 15N abundance in the leaves. / The total C pool in soil (to 20 cm depth) had not yet returned to the pre-fire levels in 2008 and it was estimated that such levels of C would be reached in another 6-7 years (about 12 years after the fire). The C and N of soil organic matter were significantly enriched in 15N and 13C isotopes after fire and had not returned to the pre-fire levels five years after the fire. It is concluded that the soil organic N pool can recover faster than the total C pool after the fire in the Alpine ash forests.

La compensación ambiental se refiere a la provisión adicional de recursos naturales, servicios ecológicos o de bienestar social a través de proyectos de reparación que son equivalentes en magnitud a las pérdidas producidas por daños ambientales. En la Unión Europea, la Directiva de Responsabilidad Medioambiental establece el marco legal para introducir responsabilidad ambiental debido a daños producidos al medio ambiente por actividades industriales. La responsabilidad ambiental establece que los recursos naturales dañados deben devolverse al estado que hubieran tenido de no producirse el daño en cuestión (restauración primaria) así como la provisión de una compensación por pérdidas acumuladas (o pérdidas provisionales) producidas desde el momento en que ha ocurrido el incidente hasta que el medio ambiente ha vuelto a su estado original (restauración compensatoria). Los Análisis de Equivalencia representan un instrumento que se utiliza para determinar la cuantía por daños al medio ambiente. Esta investigación aplica una metodología de análisis de equivalencia conocida como método valor-a-valor como una herramienta para escalar la cantidad de remediación requerida y de esta manera estimar la cantidad de reparación para compensar las pérdidas ambientales producidas tras un incendio forestal ocurrido en el noreste de España. Para efectos del Análisis de Equivalencia de Valor (AEV) se ha diseñado un ejercicio de Valoración Contingente (VC) que estima la media de la cantidad mínima de compensación física requerida para compensar los daños producidos según las preferencias sociales. A continuación, el estudio explora cuestiones que tienen que ver con la localización del proyecto de remediación cuando éste se sitúa a cierta distancia del sitio dañado. Intuitivamente, la idea de que la ubicación de un proyecto de restauración se encuentre alejado de la ubicación inicial (la zona dañada) podría implicar una mayor cantidad de compensación en comparación a un proyecto de reparación localizado más próximo al sitio del daño. Para este fin se ha diseñado un ejercicio adicional que utiliza modelos de elección que permite estimar la cantidad de compensación requerida cuando el proyecto de reparación se localiza en un sitio distinto al de la zona afectada. Finalmente, la última parte de esta investigación explora los efectos en la disposición a pagar de la información proporcionada en el cuestionario relacionada con los pagos de un programa de reparación; específicamente, cómo pagarán por el programa y si los pagos corresponden a valores nominales o reales. Con el fin de analizar este tema la pregunta de valoración toma una forma dicotómica simple en la cual los pagos deben hacerse anualmente, durante diez años, y con incrementos anuales de acuerdo a la inflación. / Environmental compensation implies the provision of additional natural resources, services or social welfare through restoration projects that are scaled to equal the losses due to environmental damage. The Environmental Liability Directive provides legal framework in the European Union for introducing environmental liability due to damages to the environment caused by industrial operators. Environmental liability requires that harmed natural resources be restored to baseline conditions (primary restoration) and compensated for the accumulated losses (interim losses) produced from the time of the incident until the environment reaches baseline conditions (compensatory restoration). Equivalency Analysis is a methodology used to determine compensation for environmental damage. This study uses an Equivalency Analysis (EA) approach namely the value-to-value approach as a tool to scale remediation and to estimate the amount of compensatory restoration to off-set an environmental damage following a wild forest fire in the northeast of Spain. Value Equivalency Analysis (VEA) is undertaken by a Contingent Valuation (CV) exercise to determine the welfare loss from the initial damage and interim loss and then a remediation project that can be established based on that information. The study elicits the minimum amount of compensation required to make individuals as well off as they would be in the baseline situation. After this the study explores remediation located at a geographical distance from the site of damage. In some cases displacement between damaged resources and restored resources is allowed, this study explores whether longer distance from the damaged site could imply a larger amount of compensation to offset the change in natural resource location. For this, an additional exercise was designed to estimate the trade-off rate for compensating in a farther away site using choice experiment techniques. Finally, the last section focuses on the information provided to respondents regarding payments in the survey instrument. This includes informing respondents how they would pay for the restoration program and whether payments correspond to nominal or real values. The survey instrument takes the form of a single bounded dichotomous choice where the payments are to be made every year over a ten year period and they would go up every year according to inflation.

Prescribed burns are employed in the southern boreal forest of northwest Ontario, Canada, as a method of re-instating fire in this fire-dependent landscape. They are also used to manage fuel loads associated with tree mortality from defoliating insects and from blow-downs, as well as in-site preparation following harvest. The natural fire season in boreal Canada typically runs from April through September and is most often characterized by stand replacing fires. However, prescribed burns in northwestern Ontario are mostly scheduled for October when fire crews and equipment are available and fire hazard is reduced. In this study, three recent fires: a spring prescribed natural fire, a summer wildfire, and a fall prescribed burn were examined to assess the effect of season on post-fire legacies in red-pine mixedwood stands in Quetico Provincial Park, northwestern Ontario. Legacies were assessed by tree, shrub and herb species composition, and by measurements of structure such as litter depth, basal areas of live trees and coarse woody debris. Tree species diversity was nearly identical. Post-fire stand structure varied widely between the different sites. The spring treatment experienced the least mortality of trees (10% of basal area dead); the summer treatment had the highest mortality (100%); and the fall prescribed burn was intermediate with 49% dead. The effect of the fall burn on the forest was probably more intense than that of a comparable natural fall fire because of the way in which it was managed, thus partly compensating for the late season. <br /><br /> This research suggests that all fires are not equal. Different post-fire structure will have lasting ecological implications such as varying edge to interior ratios, and forest habitats. From a policy perspective this is important because maintaining ecological processes including fire is mandated for some provincial parks. In addition, the new Fire Policy for Ontario has established targets to limit wildfires, and permit ecologically renewing fires, without recognition of the variability of the effects of fire or fire legacies.

Prescribed burns are employed in the southern boreal forest of northwest Ontario, Canada, as a method of re-instating fire in this fire-dependent landscape. They are also used to manage fuel loads associated with tree mortality from defoliating insects and from blow-downs, as well as in-site preparation following harvest. The natural fire season in boreal Canada typically runs from April through September and is most often characterized by stand replacing fires. However, prescribed burns in northwestern Ontario are mostly scheduled for October when fire crews and equipment are available and fire hazard is reduced. In this study, three recent fires: a spring prescribed natural fire, a summer wildfire, and a fall prescribed burn were examined to assess the effect of season on post-fire legacies in red-pine mixedwood stands in Quetico Provincial Park, northwestern Ontario. Legacies were assessed by tree, shrub and herb species composition, and by measurements of structure such as litter depth, basal areas of live trees and coarse woody debris. Tree species diversity was nearly identical. Post-fire stand structure varied widely between the different sites. The spring treatment experienced the least mortality of trees (10% of basal area dead); the summer treatment had the highest mortality (100%); and the fall prescribed burn was intermediate with 49% dead. The effect of the fall burn on the forest was probably more intense than that of a comparable natural fall fire because of the way in which it was managed, thus partly compensating for the late season. <br /><br /> This research suggests that all fires are not equal. Different post-fire structure will have lasting ecological implications such as varying edge to interior ratios, and forest habitats. From a policy perspective this is important because maintaining ecological processes including fire is mandated for some provincial parks. In addition, the new Fire Policy for Ontario has established targets to limit wildfires, and permit ecologically renewing fires, without recognition of the variability of the effects of fire or fire legacies.