This study tested the performance of classification, regression, and ordination techniques to evaluate the spatiotemporal dynamics of threats to big sagebrush ecological sites. The research was focused on invasion by annual exotic grasses and encroachment by woodlands. We sought to identify those areas that have had a persistent coverage of cheatgrass (Bromus tectorum) in big sagebrush ecological sites. We took advantage of the contrast in greenness between multi-temporal (within one year) remotely sensed vegetation indices captured in the spring and summer to find a distinct phenological signature that allowed mapping cheatgrass. We utilized support vector machines (SVM) to classify three temporal scenarios for which field data sets were available. SVM performed very well with accuracies of 70% (producer's) and 95% (user's) for the class of interest (presence of cheatgrass). This was the focus of chapter 2. In chapter 3 we report the development of vegetation continuous fields (VCF) for three years of interest 1996, 2001, and 2007 in order to detect active woodland encroachment. We prepared VCF for shrubs, trees, herbaceous vegetation, and bare ground using a suite of remotely sensed spectral reflectance, vegetation indices, and transformations. We compared the performance of multivariate regression trees (MRT) and random forests (RF) to develop the VCF multi-temporal series. RF outperformed MRT in both accuracy and ability to appropriately map the continuum of percent cover across large landscapes. We estimate that 17,570 hectares of big sagebrush lands showed encroachment by woodlands. Our goal in chapter 4 was to develop a similarity index for large rangeland landscapes. Trend assessments field sites and a long-term annual series (1984 - 2008) of remotely sensed imagery were used in conjunction with multidimensional scaling (MDS) to measure ecological distance to undesired states such as invasion by exotic annuals and encroachment by woodlands. In this chapter our units of analysis were soil-mapping units, which were predominantly composed of one ecological site (>60%). Our MDS results show that different ecological sites can be identified in the reduced MDS statistical space. The observed transitions and trajectories of mountain, Wyoming, and basin big sagebrush sites correlated well with the ecological expectation in semiarid lands. We anticipate that managers can use our protocols to update ecological site descriptions and state and transition models from a remotely sensed perspective.

Ce travail est consacré à l’étude expérimentale et numérique de la propagation des feux de végétation à l’échelle du laboratoire. Une méthode de suivi de front de flamme par caméras visibles a été développée pour reconstruire et mesurer les propriétés du front au cours du temps. Les données recueillies comprennent la vitesse de propagation (Rate Of Spread), l’épaisseur du front, les longueurs du contour du front, les profils de hauteur et la puissance du feu. Une campagne expérimentale de 105 expériences de propagation sur de la frisure de bois a été réalisée sur la plateforme PROMETHEI (Plateforme de Recherche Opérationnelle en Métrologie Thermique dédiée aux Essais Incendies) du laboratoire LEMTA. Elle contient notamment une étude de l’effet de la largeur et de la charge sur la dynamique de propagation (sur la vitesse et l’épaisseur). Une base de données (en libre accès sur internet) dédiée aux feux de végétation a été créée et fournit les positions du front de flamme (avant et arrière) pour 85 expériences. Un modèle de propagation Petit Monde à réseau de cellules hexagonales a été également développé en parallèle. Plusieurs approches sont proposées pour déterminer l’évolution de l’état des cellules : la première modélise le transfert radiatif alors que la deuxième se base sur une fonction de distribution identifiée. Un algorithme d’optimisation par essaims particulaires (PSO) est employé pour estimer les différents paramètres du modèle à l’aide des résultats expérimentaux. Le modèle Petit Monde est ensuite comparé à des expériences de propagation comprenant des coupures de combustible ou des rétrécissements/élargissements de la largeur du lit / This work is devoted to the experimental and numerical study of wildland fire spread at laboratory scale. A tracking fire front method using visible cameras was used in order to follow the fire front positions during the propagation and to evaluate some fire front properties. The data include the Rate Of Spread (ROS), the fire front width, the length of fire, the profile of flames and the Heat Release Rate. An experimental campaign of 105 fire spread tests with wood shaving as fuel was conducted on the PROMETHEI plateform (Plateforme de Recherche Opérationnelle en Métrologie Thermique dédiée aux Essais Incendies) of the laboratory LEMTA. This campaign was essentially focused on the effect of the fuel bed width and the fuel loading on the fire dynamics (particularly on the ROS and fire width). An open-source data base provides the positions of the front and backing fire as a function of time. A fire spread model based on the small world concept with a hexagonal cell network was developed. Two approaches were studied: the first one is based on a radiative transfer model for the definition of the cell states and the other one is based on an estimated distribution function. A particle swarm optimization (PSO) algorithm was used for the identification of the different parameters of the model using the experimental results. Then, the model was compared to other experiments included fuel breaks or narrowing/widening of the fuel bed width

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.

The topic of this master’s thesis is design of fire fighting and rescue vehicle, more specifically wildland fire apparatus primarily intended for difficult terrain. The main aim of this design is to create functional object fulfilling ergonomic, technical, and aesthetic demands.

Prior to European settlement, black bear (Ursus americanus) were far less abundant in the state of California. Estimates from statewide harvest data indicate the California black bear population has tripled in the last 3 decades. Bears inhabit areas they formally never occurred (e.g., urban environments) and populations that were at historically low densities are now at high densities. Though harvest data are useful and widely used as an index for black bear population size and population demographics statewide, it lacks the ability to produce precise estimates of abundance and density at local scales or account for the numerous bears living in non-hunted areas. As the human population continues to expand into wildlife habitat, we are being forced to confront controversial issues about wildlife management and conservation. Habituated bears living in non-hunted, urban areas have been and continue to be a major concern for wildlife managers and the general public. My objective was to develop DNA-based capture-mark-recapture (CMR) survey techniques in wildland and urban environments in Mono County, California to acquire population size and density at local scales from 2010 to 2012. I also compared population density between the urban and wildland environment. To my knowledge, DNA-based CMR surveys for bears have only been implemented in wildland or rural environments. I made numerous modifications to the techniques used during wildland DNA-based CMR surveys to survey bears in an urban environment. I used a higher density of hair-snares than typically used in wildland studies, non-consumable lures, modified hair-snares for public safety, included the public throughout the entire process, and surveyed in the urban-wildland interface as well as the city center. These methods were efficient and accurate while maintaining human safety. I determined that there is likely a difference in population density between the urban and wildland environments. Population density was 1.6 to 2.5 times higher in the urban study area compared to the wildland study area. Considering the negative impacts urban environments can have on wildland bear populations, this is a serious management concern. The densities I found were similar to those found in other urban and wildland black bear populations. The baseline data acquired from this study can be used as part of a long-term monitoring effort. By surveying additional years, population vital rates such as apparent survival, recruitment, movement, and finite rate of population change can be estimated.

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Wildland fuels and fire behavior have been the focus of numerous studies and models which provide operational support to firefighters. However, fuel and fire complexity in live shrubs has resulted in unexpected and sometimes aggressive fire behavior. The combustion of live fuels was studied and modeled, and the results were assimilated into a shrub-scale fire behavior model which assumes fire spread by flame-fuel overlap. Fire spread models have usually assumed that radiation heat transfer is responsible for driving fire spread, but that assumption is a topic of continuing debate, and appears to contradict some experimental observations. A convection-based shrub-scale fire spread model has been developed, building on a heritage of experiments and modeling previously performed at Brigham Young University. This project has (1) characterized fundamental aspects of fire behavior, (2) integrated the resulting submodels of fire behavior into an existing shrub model framework, and (3) produced shrub-scale fire spread experiments and (4) made model comparisons. This research models fire spread as a convection-driven phenomenon and demonstrates strategies for overcoming some of the challenges associated with this novel approach.

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