This thesis analyses the relationship between the increasingly important sovereign CDS spreads and exchange rates, from a macroeconomic perspective. It attempts to address an existing gap in the empirical literature, which to date has paid limited attention to the role of exchange rates in influencing sovereign CDS spreads, and vice versa. In exploring the relationship between sovereign CDS markets and foreign exchange markets, I find relatively strong evidence of a causal relationship between these two variables. In a longer-term cointegrating relationship, I find that sovereign CDS spreads have different impacts (positive or negative) on exchange rates depending on the structural characteristics of the domestic export sectors of the countries studied. Turning to the second moment of exchange rates and sovereign CDS spreads, I examine the relationship between the volatility of sovereign CDS spreads and the volatility of exchange rates for developed economies (proxied by an index containing 10 Eurozone countries) and emerging economies (proxied by Brazil and Russia). My findings point to different mechanisms of transmission between sovereign CDS markets and foreign exchange markets with regard to developed and emerging economies: for developed economies, exchange rates affect sovereign CDS spreads through the volatility, whilst in emerging economies the exchange rates affect sovereign CDS spreads at the price level. To further analyse the determinants of sovereign CDS spreads, I incorporate additional macroeconomic fundamentals in addition to exchange rates into a model to explain sovereign CDS spreads. The results show that sovereign CDS spreads are indeed driven by most macroeconomic fundamentals. However, these results do not hold during periods of economic turmoil, in which the rising risk aversion of investors becomes a principal influence behind the sovereign CDS spreads. As changes in exchange rates are able to capture changes to risk aversion through trading in foreign exchange markets, the exchange rate retains its explanatory power to sovereign CDS spreads in ‘normal’ as well as ‘crisis’ conditions. Overall, the study provides strong support for the claim that exchange rates are an important determinant of sovereign CDS spreads, in addition to the interest rate which is highlighted in the literature review. The exchange rate – as an important fundamental indicator – can reflect the general domestic economic status, the relative international competitiveness of countries, as well as capture changes in risk aversion among investors. Therefore, using exchange rates to explain sovereign CDS spreads can help to account for both domestic and international dimensions of the ‘health’ of an economy as well as changes in investors’ attitudes.

For roughly the past 200 years land-managers have used the practice of “muirburning” to manipulate the structure of heather (Calluna vulgaris) to create a patchwork of habitat structures able to provide forage and nesting sites for red grouse (Lagopus lagopus scoticus) as well as grazing for sheep (Ovis aries) and red deer (Cervus elaphus). This thesis investigates both the behaviour and impact of management fires in recognition of the need to develop multi-aim land management practices that ensure both continued productivity and protection of biodiversity in the face of climatic and environmental change. Fuel structure and loading are crucial controlling factors on both fire behaviour and impact governing both rate of spread and heat release to the ground surface. A visual obstruction method is developed that estimates total and fine fuel loading as well as the structure of the heather canopy. In order to adequately understand fire impact a dimensional analysis approach is taken to estimating the mass of burnt heather stems. Experiments at a number of spatial and temporal scales relate variation in heather fuel moisture content to stand structure and variation in weather conditions. Monitoring shows moisture contents to be relatively stable temporally, but spatially variable. Periods of extreme low moisture contents in early spring are associated with frozen ground, winter cuticle damage and physiological drought. Such conditions may have contributed to the large number of wildfires in 2003. A replicated plot design was used to investigate the effect of weather conditions and fuel loading on fire behaviour. An empirical approach is taken to fire behaviour modelling with equations describing rate of spread and fireline intensity being developed on the basis of fuel structure descriptors and windspeed. The theoretical negative correlation between fuel bed density and rate of spread is demonstrated to hold true for heather stands, while the impact of heterogeneity in fuel bed structure is also investigated. Redundancy Analysis is used to investigate the influence of multiple predictors on a number of aspects of fire behaviour including: rate of spread, fireline intensity, flame length and ground surface heating. Data from this and previous studies are used to ground-truth a number of fire behaviour prediction systems including BehavePlus and the Canadian Fire Behaviour Prediction System. Finally linkages between fire behaviour, fire severity and heather regeneration are investigated. A number of proxy measures of ‘Immediate Severity’ are tested and used to examine the influence of fires on plant regeneration. The post-fire development of stands is shown to relate primarily to stand age and structure before burning, and to post-fire substrates rather than variation in fire behaviour and severity.

Ces travaux de thèse ont porté sur le développement d’un modèle de propagation d’un incendie de forêt et son intégration dans une chaîne opérationnelle d'aide à la lutte tactique. C'est un modèle dont la propagation s'effectue sur un réseau de sites combustibles qui prend en compte les mécanismes principaux de transfert de chaleur radiatifs et convectifs des sites en feu vers les sites sains et l'environnement. Ce modèle tient également compte du relief et des conditions locales de vent et végétation. La simulation « temps réel » a nécessité deux développements distincts. Le premier a consisté à combiner la méthode de Monte Carlo à un algorithme génétique pour créer une base de données des facteurs de vue radiatifs de la flamme sur la végétation environnante, pour une large gamme de propriétés de flammes et de conditions environnementales. Le second repose sur une méthode de suivi du front de feu afin de limiter les données manipulées aux seules données utiles au calcul de sa propagation. La phase de validation a porté sur l’analyse comparative des contours de feux calculés par le modèle avec ceux mesurés lors de deux brûlages dirigés, dont un réalisé en Thaïlande dans le cadre de cette thèse, et ceux mesurés lors du feu de Favone de 2009 en Corse et d'un feu de grande ampleur aux États-Unis. Les temps de calcul sont très inférieurs au temps réel. Le modèle a été ensuite étendu pour permettre une évaluation du risque incendie à l’interface forêt-habitat. Dans le cadre du projet TechForFire, porté par la société NOVELTIS, il a été enfin couplé aux différents modules de la chaîne opérationnelle. La chaîne complète a été validée sur le feu historique de Velaux de 2015. / This thesis work is focused on the development of a wildfire spread model and its integration into a decision-making tool for planning firefighting operations. The fire spread model is based on a network model to represent vegetation distribution on land and considers the main heat transfer mechanisms from burning to unburnt vegetation items (i.e. radiation from the flaming zone and embers, surface convection and wind-driven convection through the fuel bed, and radiative cooling from the heated fuel element to the environment). The effects of local conditions of wind, topography, and vegetation are included. To address the challenge of real-time fire spread simulations, the model is also extended in two ways. First, the Monte Carlo method is used in conjunction with a genetic algorithm to create a database of radiation view factors from the flame to the fuel surface for a wide variety of flame properties and environment conditions. Second, the front-tracking method is introduced in order to reduce the amount of data to store and handle during propagation. The fire spread model is validated against data from different fire scenarios, showing it is capable of capturing the trends observed in experiments in terms of rate of spread, and area and shape of the burn, with reduced computational resources. It is then extended to evaluate fire risk at the wildland fire interface. In the frame of the TechForFire project coordinated by the NOVELTIS company, the new version of the fire spread model is coupled with the other modules of the operational chain. Finally, data from the fire of Velaux in 2015 are used to evaluate the TechForFire solution.

Wildfires are a natural process critical to the health of forests around the world. However, recent decades have witnessed unprecedented wildfire seasons in many forested regions, leading to a range of unprecedented socio-economic, environmental, and human health impacts. Mitigating these impacts relies in part on fire behaviour prediction systems, which provide information to assist operational wildfire managers with addressing wildfire risk and prioritizing wildfire fighting efforts. A key aspect of fire behaviour prediction systems are rate of spread models that rely on observational and experimental fire behaviour data from naturally occurring wildfires and prescribed burns, respectively. Given the challenge with observing and measuring wildfires in situ, rate of spread models typically rely on a small set of data inputs that are not always representative of the range of wildfires occurring in certain forest types. Furthermore, existing fire behaviour models often lack empirical data on forests that have more recently experienced significant compositional shifts due to climate change or various ecological or anthropogenic disturbances. To address these shortcomings, the objective of this thesis is to establish a method of acquiring empirical fire behaviour data to enhance fire behaviour prediction science through two distinct studies. The first evaluates the utility of monophotogrammetry to extract fire behaviour data from oblique aerial wildfire photographs. The results demonstrate how this approach can provide new and accurate fire spread observations to inform fire behaviour prediction or other aspects of wildland fire science where databases of such wildfire photos exist. The second study is an empirical wildfire spread analysis in forest stands affected by mountain pine beetle (MPB), and utilizes the method of monoplotting to acquire spread rate data from wildfire photographs of grey-attack MPB-affected forest stands. Results from this study further demonstrate the efficacy of the previously established monoplotting technique while providing novel empirical evidence of fire behaviour in grey attack MPB-affected forest stands. Overall, the research results presented in this thesis demonstrate the potential of monophotogrammetry for the acquisition of fire behaviour data and evaluating the results derived from fire behaviour prediction systems in different ecological contexts. This thesis exhibits the potential for this method to expand into other areas of fire behaviour, such as flame or smoke plume dimensions, spotting, and the relationship between fire behaviour and disturbance events such as pest insect outbreaks. / Graduate / 2023-04-14

Das Amazonasgebiet hat in den letzten Jahrzehnten eine Intensivierung der menschlichen Aktivitäten erfahren, die in Verbindung mit häufigen schweren Dürren die Umwelt anfälliger für Brände gemacht hat. In dieser Dissertation wurden Fernerkundungsdaten analysiert, um die räumlich-zeitliche Verteilung der Feuer in den letzten 20 Jahren im brasilianischen Amazonasgebiet umfassend zu untersuchen und die verschiedenen Brandursachen zu entschlüsseln. (I) Die erste Forschungsarbeit wertete die Verteilung der verbrannten Fläche aus und zeigte, dass die meisten Brände auf bewirtschafteten Weiden und in den immergrünen Tropenwäldern auftraten, was die Behauptung stützt, dass ihr Auftreten stark auf anthropogene Landnutzungsänderungen reagiert. Die Ergebnisse zeigten auch, dass weder Entwaldung noch Walddegradierung mit Waldbränden korrelierte, wohl aber Feuer, die auf Weiden oder Ackerflächen gelegt wurden und in den angrenzenden Wald übergesprungen sind. (II) Die zweite Forschungsarbeit analysierte einzelne Brände, die durch den auf komplexen Netzwerken basierenden FireTracks-Algorithmus identifiziert wurden. Der Algorithmus wurde verwendet, um Feuerregime für sechs verschiedene Landnutzungsklassen zu ermitteln. Die integrierte Größe, Dauer, Intensität und Ausbreitungsrate dieser räumlich-zeitlichen Brandcluster in den verschiedenen Landnutzungstypen zeigte auf, wie seltene Waldbrände, die natürlicherweise nicht in immergrünen tropischen Wäldern vorkommen, sich zu einem Feuerregime entwickelten, das für Savannenbrände typisch ist. (III) Die dritte Forschungsarbeit analysierte extreme, d. h. die intensivsten Einzelfeuer in immergrünen tropischen Wäldern, und zeigte deren großen Anteil an der insgesamt verbrannten Waldfläche. Während der globale Klimawandel das Potenzial hat, die Trockenheit zu verstärken, sind die anthropogenen Ursachen der Waldzerstörung die Zündquellen, die die Verteilung extremer Brände in den empfindlichen tropischen Wäldern bestimmen. / The Amazon region has experienced an intensification of human activities in the last decades, which combined with frequent severe droughts has led to an environment more susceptible to fire. Remotely sensed data is employed to comprehensively analyse the spatio-temporal fire distribution in the Brazilian Legal Amazon over the past 20 years to disentangle the diverse fire drivers in the region. Special focus is given to burned tropical evergreen forests.  (I) The evaluation of the burned area distribution revealed that most of it occurred in pastures and tropical evergreen forests, supporting the claim that fire incidence responds strongly to anthropogenic land-use changes. The results also showed that neither deforestation nor degradation correlated with forest fires, but escaping fires from pastures and agriculture do. (II) The analysis of individual fires identified by the complex networks based FireTracks algorithm led to the characterization of six different land cover-dependent fire regimes (fire size, duration, intensity, and rate of spread), which uncovered how evergreen forest fires have escalated from being naturally rare to showing characteristics more typical of savanna fires. (III) The analysis of extreme (most intense) fires in evergreen forests showed their large contribution to the total forest burned. While global climate change has the potential to increase drought conditions, anthropogenic drivers of forest degradation provide the ignition sources that determine extreme fire distribution in the tropical forests. The findings call for the development of control and monitoring plans to prevent fires from escaping from managed lands into forests, better management techniques to support effective land use and ecosystem management, targeting forest degradation in addition to deforestation, and considering the human factor in fire ignition and spread in Dynamic Global Vegetation Models in order to reduce uncertainty in fire regime projections.