Academic literature on the topic 'Crown fire'
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Journal articles on the topic "Crown fire":
1
Ex, Seth, Frederick W. Smith, and Tara L. Keyser. "Characterizing crown fuel distribution for conifers in the interior western United States." Canadian Journal of Forest Research 45, no. 7 (July 2015): 950–57. http://dx.doi.org/10.1139/cjfr-2014-0503.
Abstract:
Canopy fire hazard evaluation is essential for prioritizing fuel treatments and for assessing potential risk to firefighters during suppression activities. Fire hazard is usually expressed as predicted potential fire behavior, which is sensitive to the methodology used to quantitatively describe fuel profiles: methodologies that assume that fuel is distributed uniformly throughout crowns have been shown to predict less severe fire behavior than those that assume more realistic nonuniform fuel distributions. We used crown fuel data from seven interior western United States conifer species to characterize within-crown fuel distributions. Fuel was shifted upward and concentrated in crowns in crowded stands compared with crowns in open stands, which suggests that the vertical distribution of fuel is shaped by foliage concentration in favorable light environments near the top of crowns and echoes the predictable relationship between crown ratio and stand density. However, unlike crown ratio, the relationship between within-crown foliage distribution and stand density was independent of the shade tolerance of a species. This implies that there is a general relationship between stand density and within-crown fuel distribution for conifers and that species differences in fuel profiles related to shade tolerance are expressed primarily in the relationship between stand density and crown ratio.
2
Rodríguez y Silva, Francisco, Mercedes Guijarro, Javier Madrigal, Enrique Jiménez, Juan R. Molina, Carmen Hernando, Ricardo Vélez, and Jose A. Vega. "Assessment of crown fire initiation and spread models in Mediterranean conifer forests by using data from field and laboratory experiments." Forest Systems 26, no. 2 (July 24, 2017): e02S. http://dx.doi.org/10.5424/fs/2017262-10652.
Abstract:
Aims of study: To conduct the first full-scale crown fire experiment carried out in a Mediterranean conifer stand in Spain; to use different data sources to assess crown fire initiation and spread models, and to evaluate the role of convection in crown fire initiation.Area of study: The Sierra Morena mountains (Coordinates ETRS89 30N: X: 284793-285038; Y: 4218650-4218766), southern Spain, and the outdoor facilities of the Lourizán Forest Research Centre, northwestern Spain.Material and methods: The full-scale crown fire experiment was conducted in a young Pinus pinea stand. Field data were compared with data predicted using the most used crown fire spread models. A small-scale experiment was developed with Pinus pinaster trees to evaluate the role of convection in crown fire initiation. Mass loss calorimeter tests were conducted with P. pinea needles to estimate residence time of the flame, which was used to validate the crown fire spread model.Main results: The commonly used crown fire models underestimated the crown fire spread rate observed in the full-scale experiment, but the proposed new integrated approach yielded better fits. Without wind-forced convection, tree crowns did not ignite until flames from an intense surface fire contacted tree foliage. Bench-scale tests based on radiation heat flux therefore offer a limited insight to full-scale phenomena.Research highlights: Existing crown fire behaviour models may underestimate the rate of spread of crown fires in many Mediterranean ecosystems. New bench-scale methods based on flame buoyancy and more crown field experiments allowing detailed measurements of fire behaviour are needed.
3
Cohn, Gregory M., Russell A. Parsons, Emily K. Heyerdahl, Daniel G. Gavin, and Aquila Flower. "Simulated western spruce budworm defoliation reduces torching and crowning potential: a sensitivity analysis using a physics-based fire model." International Journal of Wildland Fire 23, no. 5 (2014): 709. http://dx.doi.org/10.1071/wf13074.
Abstract:
The widespread, native defoliator western spruce budworm (Choristoneura occidentalis Freeman) reduces canopy fuels, which might affect the potential for surface fires to torch (ignite the crowns of individual trees) or crown (spread between tree crowns). However, the effects of defoliation on fire behaviour are poorly understood. We used a physics-based fire model to examine the effects of defoliation and three aspects of how the phenomenon is represented in the model (the spatial distribution of defoliation within tree crowns, potential branchwood drying and model resolution). Our simulations suggest that fire intensity and crowning are reduced with increasing defoliation compared with un-defoliated trees, regardless of within-crown fuel density, but torching is only reduced with decreasing crown fuel density. A greater surface fire intensity was required to ignite the crown of a defoliated compared with an un-defoliated tree of the same crown base height. The effects of defoliation were somewhat mitigated by canopy fuel heterogeneity and potential branchwood drying, but these effects, as well as computational cell size, were less pronounced than the effect of defoliation itself on fire intensity. Our study suggests that areas heavily defoliated by western spruce budworm may inhibit the spread of crown fires and promote non-lethal surface fires.
4
Raymond, Crystal L., and David L. Peterson. "Fuel treatments alter the effects of wildfire in a mixed-evergreen forest, Oregon, USA." Canadian Journal of Forest Research 35, no. 12 (December 1, 2005): 2981–95. http://dx.doi.org/10.1139/x05-206.
Abstract:
We had the rare opportunity to quantify the relationship between fuels and fire severity using prefire surface and canopy fuel data and fire severity data after a wildfire. The study area is a mixed-evergreen forest of southwestern Oregon with a mixed-severity fire regime. Modeled fire behavior showed that thinning reduced canopy fuels, thereby decreasing the potential for crown fire spread. The potential for crown fire initiation remained fairly constant despite reductions in ladder fuels, because thinning increased surface fuels, which contributed to greater surface fire intensity. Thinning followed by underburning reduced canopy, ladder, and surface fuels, thereby decreasing surface fire intensity and crown fire potential. However, crown fire is not a prerequisite for high fire severity; damage to and mortality of overstory trees in the wildfire were extensive despite the absence of crown fire. Mortality was most severe in thinned treatments (80%100%), moderate in untreated stands (53%54%), and least severe in the thinned and underburned treatment (5%). Thinned treatments had higher fine-fuel loading and more extensive crown scorch, suggesting that greater consumption of fine fuels contributed to higher tree mortality. Fuel treatments intended to minimize tree mortality will be most effective if both ladder and surface fuels are treated.
5
Ritter, Scott M., Chad M. Hoffman, Mike A. Battaglia, Rodman Linn, and William E. Mell. "Vertical and Horizontal Crown Fuel Continuity Influences Group-Scale Ignition and Fuel Consumption." Fire 6, no. 8 (August 18, 2023): 321. http://dx.doi.org/10.3390/fire6080321.
Abstract:
A deeper understanding of the influence of fine-scale fuel patterns on fire behavior is essential to the design of forest treatments that aim to reduce fire hazard, enhance structural complexity, and increase ecosystem function and resilience. Of particular relevance is the impact of horizontal and vertical forest structure on potential tree torching and large-tree mortality. It may be the case that fire behavior in spatially complex stands differs from predictions based on stand-level descriptors of the fuel distribution and structure. In this work, we used a spatially explicit fire behavior model to evaluate how the vertical and horizontal distribution of fuels influences the potential for fire to travel from the surface into overstory tree crowns. Our results support the understanding that crown fuels (e.g., needles and small-diameter branchwood) close to the surface can aid in this transition; however, we add important nuance by showing the interactive effect of overstory horizontal fuel connectivity. The influence of fuels low in the canopy space was overridden by the effect of horizontal connectivity at surface fire-line intensities greater than 1415 kW/m. For example, tree groups with vertically continuous fuels and limited horizontal connectivity sustained less large-tree consumption than tree groups with a significant vertical gap between the surface and canopy but high-canopy horizontal connectivity. This effect was likely the result of reduced net vertical heat transfer as well as decreased horizontal heat transfer, or crown-to-crown spread, in the upper canopy. These results suggest that the crown fire hazard represented by vertically complex tree groups is strongly mediated by the density, or horizontal connectivity, of the tree crowns within the group, and therefore, managers may be able to mitigate some of the torching hazard associated with vertically heterogenous tree groups.
6
McCaskill, George. "The Hungry Bob Fire & Fire Surrogate Study: A 20-Year Evaluation of the Treatment Effects." Forests 10, no. 1 (December 28, 2018): 15. http://dx.doi.org/10.3390/f10010015.
Abstract:
The Hungry Bob fuels reduction project was part of a 12-site National Fire and Fire Surrogate (FFS) network of experiments conducted across the United States from the late 1990s through the early 2000s to determine the regional differences in applying alternative fuel-reduction treatments to forests. The Hungry Bob project focused on restoration treatments applied in low elevation, dry second-growth ponderosa pine (Pinus ponderosa subsp. ponderosa (Douglas ex C. Lawson) and Douglas-fir (Pseudotsuga menziesii subsp. glauca (Beissn.) Franco forests of northeastern Oregon. Treatments included a single entry thin from below in 1998, a late season burn in 2000, a thin (1999) followed by burning (2000), and a no-treatment control. This paper represents results 20 years after treatments and focuses on the treatment effects upon tree diameter growth, crown health, and ladder fuel conditions within the dry eastside stands. The Thin + Burn units produced the best diameter growth in ponderosa pine trees, whereas the Thin units had the best growth for Douglas-fir. The Burn treatment did not improve diameter growth over the Controls. The Thin + Burn treatments also produced trees with the highest tree crown ratios. The Burn unit trees had lower crown ratios compared to the Control trees. The crown reduction (reduction in tree crown ratio since 2004) was largest in the Burn-only units and smallest in the Thin + Burn units. Finally, the heights to the lower tree crowns were highest in the Thin + Burn trees and lowest in the Burn unit trees. Based upon the 20-year responses, the Thin + Burn treatments produced the best conditions for stand growth, while limiting fire stress upon residual tree crowns. It also proved most effective at reducing ladder fuels as represented by higher tree crown heights.
7
Cruz, Miguel G., Martin E. Alexander, and Ronald H. Wakimoto. "Development and testing of models for predicting crown fire rate of spread in conifer forest stands." Canadian Journal of Forest Research 35, no. 7 (July 1, 2005): 1626–39. http://dx.doi.org/10.1139/x05-085.
Abstract:
The rate of spread of crown fires advancing over level to gently undulating terrain was modeled through nonlinear regression analysis based on an experimental data set pertaining primarily to boreal forest fuel types. The data set covered a significant spectrum of fuel complex and fire behavior characteristics. Crown fire rate of spread was modeled separately for fires spreading in active and passive crown fire regimes. The active crown fire rate of spread model encompassing the effects of 10-m open wind speed, estimated fine fuel moisture content, and canopy bulk density explained 61% of the variability in the data set. Passive crown fire spread was modeled through a correction factor based on a criterion for active crowning related to canopy bulk density. The models were evaluated against independent data sets originating from experimental fires. The active crown fire rate of spread model predicted 42% of the independent experimental crown fire data with an error lower then 25% and a mean absolute percent error of 26%. While the models have some shortcomings and areas in need of improvement, they can be readily utilized in support of fire management decision making and other fire research studies.
8
Karna, Yogendra K., Trent D. Penman, Cristina Aponte, and Lauren T. Bennett. "Assessing Legacy Effects of Wildfires on the Crown Structure of Fire-Tolerant Eucalypt Trees Using Airborne LiDAR Data." Remote Sensing 11, no. 20 (October 20, 2019): 2433. http://dx.doi.org/10.3390/rs11202433.
Abstract:
The fire-tolerant eucalypt forests of south eastern Australia are assumed to fully recover from even the most intense fires; however, surprisingly, very few studies have quantitatively assessed that recovery. The accurate assessment of horizontal and vertical attributes of tree crowns after fire is essential to understand the fire’s legacy effects on tree growth and on forest structure. In this study, we quantitatively assessed individual tree crowns 8.5 years after a 2009 wildfire that burnt extensive areas of eucalypt forest in temperate Australia. We used airborne LiDAR data validated with field measurements to estimate multiple metrics that quantified the cover, density, and vertical distribution of individual-tree crowns in 51 plots of 0.05 ha in fire-tolerant eucalypt forest across four wildfire severity types (unburnt, low, moderate, high). Significant differences in the field-assessed mean height of fire scarring as a proportion of tree height and in the proportions of trees with epicormic (stem) resprouts were consistent with the gradation in fire severity. Linear mixed-effects models indicated persistent effects of both moderate and high-severity wildfire on tree crown architecture. Trees at high-severity sites had significantly less crown projection area and live crown width as a proportion of total crown width than those at unburnt and low-severity sites. Significant differences in LiDAR -based metrics (crown cover, evenness, leaf area density profiles) indicated that tree crowns at moderate and high-severity sites were comparatively narrow and more evenly distributed down the tree stem. These conical-shaped crowns contrasted sharply with the rounded crowns of trees at unburnt and low-severity sites and likely influenced both tree productivity and the accuracy of biomass allometric equations for nearly a decade after the fire. Our data provide a clear example of the utility of airborne LiDAR data for quantifying the impacts of disturbances at the scale of individual trees. Quantified effects of contrasting fire severities on the structure of resprouter tree crowns provide a strong basis for interpreting post-fire patterns in forest canopies and vegetation profiles in Light Detection and Ranging (LiDAR) and other remotely-sensed data at larger scales.
9
Cruz, Miguel G., Bret W. Butler, and Martin E. Alexander. "Predicting the ignition of crown fuels above a spreading surface fire. Part II: model evaluation." International Journal of Wildland Fire 15, no. 1 (2006): 61. http://dx.doi.org/10.1071/wf05045.
Abstract:
A crown fuel ignition model (CFIM) describing the temperature rise and subsequent ignition of the lower portion of tree crowns above a spreading surface fire was evaluated through a sensitivity analysis, comparison against other models, and testing against experimental fire data. Results indicate that the primary factors influencing crown fuel ignition are those determining the depth of the surface fire burning zone and the vertical distance between the ground/surface fuel strata and the lower boundary of the crown fuel layer. Intrinsic crown fuel properties such as fuel particle surface area-to-volume ratio and foliar moisture content were found to have a minor influence on the process of crown fuel ignition. Comparison of model predictions against data collected in high-intensity experimental fires and predictions from other models gave encouraging results relative to the validity of the model system.
10
Putnam, T., and B. W. Butler. "Evaluating fire shelter performance in experimental crown fires." Canadian Journal of Forest Research 34, no. 8 (August 1, 2004): 1600–1615. http://dx.doi.org/10.1139/x04-091.
Abstract:
Fire shelters are critical safety items required for use by most wildland firefighters in the United States. Most testing of fire shelters, clothing and other personal protective equipment (PPE) has been limited to prescribed fires or laboratory based studies. This study reports results from experiments where lined and unlined stainless steel or aluminum and glass fabric shelters were tested under high intensity crown fire conditions in and adjacent to experimental burn plots. Firefighter clothing and standard (pre-2003) fire shelters were also tested. Measured shelter surface and air temperatures and thermal impact on firefighter personal protective equipment were used to deduce the survivability of shelter designs and deployment location. Multiple glass and aluminum layered shelters show more promise than stainless steel shelters for improving overall fire shelter survivability. Data collected outside the burn plots generally indicate decreased heating as distance from forest edge increases, supporting the importance of maximizing distance from vegetation for survivability. It is recommended that common experiment protocols be adopted so that future research into fire shelter and PPE performance builds on work-to-date and provides a common basis from which analyses can be completed.
Dissertations / Theses on the topic "Crown fire":
1
Page, Wesley G. "Bark Beetle-Induced Changes to Crown Fuel Flammability and Crown Fire Potential." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/2081.
Abstract:
Recent outbreaks of mountain pine beetle (Dendroctonus ponderosae Hopkins) in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forests and spruce beetle (Dendroctonus rufipennis Kirby) in Engelmann spruce (Picea engelmannii Parry ex Engelm.) forests have affected vast areas across western North America. The highlevels of tree mortality associated with these outbreaks have raised concerns amongst fire managers and wildland firefighters about the effects of the tree mortality on fire behavior, particularly crown fire behavior, as crown fires hinder the ability of firefighters to conduct safe and effective fire suppression operations. Current information regarding crown fire dynamics in recently attacked forests is limited to results obtained from simulations employing either inappropriate and/or unvalidated fire behavior models
based on inadequate descriptions of crown fuel flammability. The purpose of this research was to measure and characterize the changes in crown fuel flammability caused y recent bark beetle attack and to describe the implications of these changes on crown fire potential in affected forests.
Results indicated that bark beetle attack causes a significant decline in moisture content and change in chemical composition in lodgepole pine and Engelmann spruce tree foliage, which substantially increases foliage flammability. Additionally, it was found that conventional models used to predict the moisture content of fine, dead surface fuels were inappropriate for predicting the moisture content of foliage on mountain pine beetle-attacked lodgepole pine trees during the red stage. Therefore, calibrated operational models and models based on diffusion theory were developed and evaluated that could accurately predict hourly fluctuations in moisture content. The implications of these changes on crown fire potential are dependent upon a host of site specific factors including outbreak duration, severity, and the specific stand characteristics. Based on our results, we believe that current fire behavior models, including popular semi-empirical and physics-based models, are currently inadequate for accurately predicting crown fire potential in forests recently attacked by bark beetles. In order to make significant progress in our understanding of crown fire potential in recently attacked forests, a substantial effort to document wildfire behavior in the field and/or to conduct experimental fires is needed.
2
Botequim, Brigite Roxo. "Tools to support design of fire-resistant landscapes in Portuguese ecosystems." Doctoral thesis, ISA/UL, 2015. http://hdl.handle.net/10400.5/9257.
Abstract:
Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de AgronomiaForests are a key element in the Portuguese landscape. Moreover, fire hazard is a central challenge at national context. How can appropriate management potentially change fire behaviour, fire damage and the difficulty of fire suppression? What are the causal relationships between fire proneness, stand structure and forest stand composition? The common objective of the doctoral research among the five studies is to address the above issues based on principles of creating fire-resistant forests, underlying factors and implications for active forest management, while sustaining effective fire prevention levels. The ultimate goal is to provide forest managers and policy makers with tools to support their decisions, and more effectively align management policies, plans, and practices across fire-prone landscapes. The first research phase aims, across a range of scales from the individual tree to the stand level, respectively: (i) modelling the annual probability of wildfire occurrence of pure and even-aged eucalypt stands; (ii) developing a shrub biomass accumulation model, and (iii) a post-fire mortality model at stand level and the individual tree survival probability to mitigate damage in any forest stand structure. The second phase introduces fire behavior modeling coupled with common stand variables as a tool to (iv) assess potential crown fire occurrence through stand structure/stand composition, and (v) draw guidelines that express the difficulty of fire suppression in those fire-prone forest stands. The accuracy of the research findings can provide an interesting insight to support hazard-reduction silvicultural practices in Portuguese ecosystems
3
Deane, McKenna Daniel C. "Managing for Multiple Objectives in Southwestern Forests: Evaluating the Trade-offs between Enhancing Mexican Spotted Owl Nest Habitat and Mitigating Potential Crown Fire." DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/6878.
Abstract:
The Forest Inventory and Analysis (FIA), the United States’ forest census, measured sixty-six Mexican spotted owl nest stands in order gain insight into the structure and composition of the nest habitat of this threatened species. I used these data, along with the greater FIA database and the Forest Vegetation Simulator to explore questions surrounding the management of Mexican spotted owl habitat, specifically how to balance the objective of sustaining and enhancing nest habitat in face of increasing forest fire size and severity in the Southwest. My research consisted of three studies. The first study quantified the structure and composition of the Mexican spotted owl nest stands and scrutinized current evaluation criteria of nest habitat. The second study estimated how much of the Southwestern landscape is at risk to high-severity crown fire and how much of the landscape is suitable Mexican spotted owl nest habitat. The third study modeled forest dynamics and silvicultural intervention in potential Mexican spotted owl nest stands. The purpose of this research is to assist in management of Southwestern forests in order to decrease fire size and severity while sustaining and enhancing current and future Mexican spotted owl nest habitat.
4
Lacy, Philip Alan Physical Environmental & Mathematical Sciences Australian Defence Force Academy UNSW. "Burning Under Young Eucalypts." Awarded by:University of New South Wales - Australian Defence Force Academy. Physical, Environmental & Mathematical Sciences, 2009. http://handle.unsw.edu.au/1959.4/43663.
Abstract:
Fuels management in eucalyptus plantations is essential to minimise the impact of wildfire. Prescribed burning has the potential to reduce the fuel hazard in plantations, but is not routinely conducted due to concerns relating to tree damage. Through a series of experimental burns, the issues of tree damage are addressed and minimum tree sizes are recommended that are capable of withstanding the effects of low to moderate intensity fires. Data was collected between 2005 and 2007 over six sites, two species, and three age classes. Tree response results came from multiple measurements of over 1700 individual trees. The fuel characteristics commonly found in sub-tropical eucalypt plantations from age four to eleven are described and quantified. These fuel characteristics are related to fire behaviour and new fire behaviour models, specific to young eucalypt plantations, are presented. The fuel characteristics that most influence fire behaviour in young eucalypt plantations are fuel load, fuel height, and fuel moisture content. These characteristics can be used to predict the rate of spread of a plantation fire under benign wind conditions. A novel technique for assessing the extent of stem damage in eucalypts is developed and described. This technique enables immediate assessment of stem damage following fire; previous assessment techniques recommend waiting a considerable period of time (up to 2 years) until dead bark dropped off and fire scars were evident. This new assessment technique is likely to be suitable for post-fire assessment of any eucalypt species and will provide forest managers with the capability of deciding whether to leave a stand to ???grow-on??? or commence recovery operations. Minimum stem sizes recommended to ensure no long-term damage are between 5 ??? 8 cm DBH (diameter at breast height, i.e. 1.3m above ground level) for Eucalyptus dunnii (Dunn???s white gum) and 5 ??? 13 cm DBH for Corymbia spp. (spotted gum) depending on the quantity of fuel around the stem. Stem sizes vary between species because of the variation in bark thickness between species. This thesis provides all the necessary information to conduct prescribed burning operations in young eucalypt plantations.
5
Arantes, Carolina de Silvério. "O processo de nucleação em ambiente savânico do cerrado." Universidade Federal de Uberlândia, 2016. https://repositorio.ufu.br/handle/123456789/13286.
Abstract:
Fundação de Amparo a Pesquisa do Estado de Minas GeraisNucleation process occurs naturally at savannic areas as of the changes promoted by scattered trees that facilitate the colonization of crown area by new individuals and species, including species typical of forest environment. This process can be influenced by several factors such as the physical characteristics of the nuclei, the species of nucleus and the response of nuclei and colonizers to fire. The aim of this study was to describe the nucleation process in savannic environment of Cerrado, from: the description of the environmental changes promoted by nuclei at crown area and the influence of these changes, as well as the physical parameters (crown area and distance from forest formation) of nuclei, in the structure and composition of the community colonizing nuclei (Chapter 1); the analysis of the influence of fire on the structure, composition, functional diversity and resilience of the community colonizing nuclei (Chapter 2); and the description of the influence of the difference in the species of nucleator in the structure, composition, functional diversity and response to fire of communities colonizing the three species of nuclei. Scattered trees at savannic environments of Cerrado act as nucleating, favoring the crown area colonization by a denser and more diverse community, especially by those species typical of forest environment. The fire alters the structure and composition of the community colonizing the nuclei, which has become less dense and more diverse than the community colonizing this environment before the fire, as well as increasing functional diversity based on richness and the occurrence of resprount among individuals colonizing the community after the fire. The larger the capacity of the nucleator, regardless of species, of generating greater shading, higher humidity and higher nutrient availability, denser and more diverse the community colonizing the nuclei will be.
A nucleação ocorre de forma natural nas áreas savânicas a partir das modificações promovidas pelos indivíduos arbóreos que facilitam a colonização do ambiente abaixo da copa por novos indivíduos e espécies, incluindo espécies típicas de ambiente florestal. Este processo pode ser influenciado por vários fatores como, as características físicas do indivíduo nucleador, a espécie nucleadora e a resposta dos indivíduos nucleadores e colonizadores ao fogo. O objetivo deste estudo foi descrever o processo de nucleação em ambiente savânico do Cerrado, a partir da: descrição das modificações ambientais promovidas pelos indivíduos nucleadores na área da copa e a influência destas modificações, bem como dos parâmetros físicos dos núcleos (área da copa e distância até a formação florestal), na estrutura e composição da comunidade colonizadora dos núcleos (Capítulo 1); análise da influência do fogo na estrutura, composição, diversidade funcional e resiliência da comunidade colonizadora dos núcleos (Capítulo 2); e descrição da influência da diferença das espécies nucleadoras na estrutura, composição, diversidade funcional e resposta ao fogo das comunidades colonizadoras das três espécies nucleadoras. Os indivíduos arbóreos do cerrado sentido restrito atuam como nucleadores favorecendo a colonização da área da copa por uma maior densidade e diversidade de espécies, especialmente aquelas típicas de ambiente florestal. A ocorrência de fogo altera a estrutura e composição desta comunidade colonizadora dos núcleos, que se apresenta menos densa e com maior riqueza que a comunidade colonizadora deste ambiente antes do fogo, além de aumentando a diversidade funcional baseada na riqueza e a ocorrência de rebrota entre os indivíduos que compõem a comunidade após o fogo. Quanto maior for a capacidade do indivíduo nucleador, independente da espécie, de gerar maior sombreamento, maior umidade e maior disponibilidade de nutrientes, mais densa e mais diversa será a comunidade colonizadora deste núcleo.
Doutor em Ecologia e Conservação de Recursos Naturais
6
Jamaladdeen, Rawaa. "Investigation on Wildfire Flashovers in the Mediterranean Climate Regions with Emphasis on VOCs Contributions." Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2023. http://www.theses.fr/2023ESMA0015.
Abstract:
Cette thèse apporte des réponses aux demandes de la communauté des pompiers d'étudier les facteurs probables responsables de l'intensification des régimes de feux de forêt jusqu'aux flashovers en utilisant des approches expérimentales numériques et thermochimiques. Le modèle numérique est un modèle de dispersion de gaz validant les données expérimentales des essais en soufflerie pour résoudre la controverse quant à savoir si les accumulations de composés organiques volatils (COV) dans des topographies confinées finissent par induire des incendies de forêt. Il comprend un front de feu se propageant calculé à l'aide du modèle semi-empirique de feu de surface en régime permanent de Rothermel et de la transition de Van Wagner vers les critères de comportement des feux de cime, avec un taux instable intégré d'émissions de COV simulant ceux évoluant à partir de la combustion de la végétation dans le front de feu. Pour synchroniser nos travaux avec les données de terrain, des expériences thermochimiques ont été menées sur diverses espèces de végétation méditerranéenne afin d'examiner leurs taux d'émission de COV dans des conditions environnementales normales et stressantes, car elles pourraient finir par définir différents scénarios d'inflammabilité lors d'incendies de forêt. Premièrement, deux espèces d'arbustes méditerranéens : Cistus albidus et Rosmarinus officinalis sont explorées pour leurs émissions de COV et leurs changements physiologiques après avoir été soumises à des stress abiotiques (sécheresse et chaleur), à l'aide d'analyses par chromatographie en phase gazeuse par pyrolyse et par spectrométrie de masse (Py-GC/MS). Deux autres espèces forestières méditerranéennes : Quercus suber L. et Cupressus sempervirens horizontalis L. ont été étudiées pour leurs caractéristiques d'inflammabilité distinctives à l'aide d'analyses thermogravimétriques et thermiques différentielles (TG/DTA), couplées à une analyse Py-GC/MS pour identifier les gaz émis. lors des pics exothermiques. Cette étape vise à mieux comprendre les descripteurs d'inflammabilité de ces espèces dans le cadre d'une stratégie de gestion forestière plus efficace par laquelle, en favorisant la plantation de certaines espèces moins inflammables dans les mesures sylvicoles, on pourrait protéger d'autres espèces plus inflammables mais économiquement précieuses, des dangers des incendies de forêt et leurs comportements extrêmes. Les espèces de la végétation méditerranéenne sont d'importants émetteurs de COV, en particulier lorsqu'ils sont provoqués par des stress externes lors d'incendies de forêt. Cependant, certains COV biogènes (COBV), plus particulièrement les sesquiterpènes, ne sont pas encore complètement couverts pour leurs caractéristiques d'inflammabilité, telles que leurs limites inférieure et supérieure d'inflammabilité, leur auto-inflammation, températures, points d'éclair, etc. Une telle lacune scientifique qu'il a fallu enrichir en étudiant les limites d'inflammabilité du β-Caryophyllène, l'un des plus importants sesquiterpènes émis par la végétation méditerranéenne. Des tests préliminaires pour mesurer les pressions de vapeur du β-Caryophyllène sont menés en vue d'expérimenter ses limites d'inflammabilité dans une bombe sphérique comme plans futurs. Les travaux de cette thèse doivent être considérés comme la première étape d'une approche plus globale qui devrait fournir aux personnels opérationnels de lutte contre les incendies un outil d'aide à la décision complet, capable de façonner leurs stratégies de gestion forestière pour protéger les milieux naturels et les pompiers des dangers des comportements extrêmes des incendies de forêtRequests from the firefighting communities are increasing urging the scientific communities to create operational protective and preventive tools that help them understand extreme wildfire behaviors considering not only the atmospheric conditions but also topography, and vegetation characteristics. Thus, our objective was to provide answers to such requests by investigating the probable factors responsible for intensifying wildfire regimes to flashovers using numerical, and thermobiochemical experimental approaches. The numerical model is a gas dispersion model validating experimental data from wind tunnel tests to resolve the controversy of whether or not the volatile organic compounds (VOCs) accumulations in confined topographies end up inducing wildfire flashovers. It comprises a propagating fire front calculated using the Rothermel semi-empirical steady-state surface fire model, and Van Wagner transition to crown fire behavior criteria, with an integrated unsteady rate of VOC emissions simulating the ones evolving from the vegetation burning in the firefront. To synchronize our work with field input, thermochemical experiments were conducted on various Mediterranean vegetation species to examine their VOC emission rates in normal and stressful environmental conditions as they may end up defining different flammability scenarios in wildfires. First, two Mediterranean shrub species: Cistus albidus and Rosmarinus officinalis are explored for their VOC emissions and physiological changes after being subjected to abiotic stresses (drought and heat), using pyrolysis-gas chromatography and mass spectrometry (Py-GC/MS) analyses. Two other Mediterranean forest species: Quercus suber L. and Cupressus sempervirens horizontalis L. were investigated for their distinctive flammability characteristics using thermo-gravimetric and differential thermal analyses (TG/DTA), coupled with Py-GC/MS analysis to identify the gases emitted during the exo-thermic peaks. This step aims to better understand the flammability descriptors of these species as a part of a more efficient forest management strategy by which, favoring the plantation of certain lesser flammable species in silviculture measures may protect other more flammable but economically valuable species, from the dangers of wildfires and their extreme behaviors. Mediterranean vegetation species are important VOC emitters especially when provoked by external stresses during wildfires however, some biogenic VOCs (BVOCs), more particularly sesquiterpenes, are still not thoroughly covered for their flammability characteristics, such as their lower and upper flammability limits, auto-ignition temperatures, flashpoints, etc. Such a scientific lack we found it necessary to enrich by studying the flammability limits of β-Caryophyllene, one of the most important sesquiterpenes emitted from Mediterranean vegetation. Preliminary tests for measuring the vapor pressures of β-Caryophyllene are conducted in preparation for experimenting its flammability limits in a spherical bomb as future plans. The work in this thesis should be considered as the first step in a more global approach that should provide operational firefighting staff, with a comprehensive decision-making tool capable of shaping their forest management strategies from wildfire characteristics themselves and protecting wildlands and firefighters equally from the dangers and extreme behaviors of wildfire flashovers
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Gupta, Indra. "Use of crown length to define stem form : segmented taper equation /." Thesis, Connect to this title online; UW restricted, 1986. http://hdl.handle.net/1773/5593.
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Mårtensson, Charlie, and Jacob Brännström. "Simulating Effects of Agent Velocity Changes on Crowd Behavior During Fire Emergency Evacuations." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302345.
Abstract:
Fire emergencies are both deadly and difficult to accurately model in real life. Computer-simulated crowds provide a way to observe the possible outcome of a fire emergency evacuation without endangering real human subjects. However, many previous studies in this area do not account for the fact that evacuating people will not move at a constant velocity, but rather speed up to attempt to evade danger. The aim of this study is to explore how agents increasing their velocity when in close proximity to a fire threat affects the results of a simulated emergency evacuation from a classroom environment. Using the game engine Unity3D, simulations were conducted of evacuations from three different classrooms of varying size, accommodating a small, medium, and large number of seats, and a corresponding number of agents. A fire object, which could either remain stationary or propagate through the room, was placed in one of two different locations in each room: near the exit and in a corner far from the exits. For each possible configuration, simulations were run both with and without the ability for agents to dynamically increase their velocity. The evacuation times and number of fatalities were noted. The experiment showed that allowing agents to speed up when in proximity to a threat led to shorter evacuation times and fewer fatalities compared to when the agents were limited to moving at a constant velocity. This is at odds with real-life data, which has shown that attempts to move faster can result in slower evacuations due to crowding behavior. The discrepancy is likely a result of unrealistic modeling of the interpersonal friction, i.e. pushing behavior, between agents. However, clear differences were observed compared to the experiments with constant velocity, which showcases the importance of continuing this overlooked research area in the pursuit of creating true-to-life emergency simulations.Eldsvådor är både livsfarliga och svåra att modellera i verkliga livet. Med hjälp av datorsimulerade folkmassor kan resultatet av en evakuering under eldsvåda observeras utan att försätta försökspersoner i fara. Mycket av den tidigare forskningen inom området räknar dock inte med faktumet att evakuerande människor inte rör sig med konstant hastighet, utan att de i själva verket springer för att fly undan fara. Syftet med denna studie är att undersöka hur resultatet av en simulerad evakuering från en klassrumsmiljö påverkas av att agenter kan öka sin hastighet i närheten av en eldsvåda. Spelmotorn Unity3D användes för att köra simulerade evakueringar från tre olika klassrum, med litet, mellanstort och stort antal sittplatser och motsvarande antal agenter. Ett eldobjekt, som antingen kunde förbli orörligt eller sprida sig genom rummet, placerades på två olika platser i varje rum: nära utgången respektive i ett hörn långt bort från utgången. För var och en av dessa konfigurationer kördes simulationer både med och utan möjligheten för agenter att dynamiskt öka sin hastighet. Evakueringstiden och antalet dödsfall noterades. Experimentet visade att möjligheten för agenter att röra sig snabbare i närheten av ett hot ledde till kortare evakueringstider och färre döda, jämfört med när agenterna begränsades till konstant hastighet. Detta står i motsägelse till data från verkliga livet, som visar att försök att röra sig snabbare vid flykt kan leda till långsammare evakueringar till följd av trängsel. Avvikelsen beror sannolikt på brister i modelleringen av friktion och knuffande beteende mellan agenter. Tydliga skillnader observerades dock gentemot experimenten med konstant hastighet, vilket tyder på vikten av vidare forskning i detta förbisedda område i strävan att skapa verklighetstrogna simuleringar av nödsituationer.
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Farrell, Bethany Megan. "Gems for Her Crown: The Stained Glass Drum Oculi of Santa Maria del Fiore." Master's thesis, Temple University Libraries, 2013. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/233293.
Abstract:
Art HistoryM.A.
The literature on the stained glass windows installed in the eight oculi of the drum of Santa Maria del Fiore are mainly found in the monographs of the four artists that provided the cartoons--Donatello, Lorenzo Ghiberti, Paolo Uccello, and Andrea del Castagno. Few studies have focused on the program in its entirety. This thesis will attempt to provide a more thorough understanding of the program. Analysis of the primary documents reveals how the windows functioned as part of the building and its liturgical and public life. In particular, the central argument is that Donatello's Coronation of the Virgin was a substitute for an altarpiece and the seven other windows act as subsidiary scenes that reinforce the primary window and its political and theological agenda.
Temple University--Theses
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Jaganathan, Sivakumar. "ON THE INCORPORATION OF THE PERSONALITY FACTORS INTO CROWD SIMULATION." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4113.
Abstract:
Recently, a considerable amount of research has been performed on simulating the collective behavior of pedestrians in the street or people finding their way inside a building or a room. Comprehensive reviews of the state of the art can be found in Schreckenberg and Deo (2002) and Batty, M., DeSyllas, J. and Duxbury, E. (2003). In all these simulation studies, one area that is lacking is accounting for the effects of human personalities on the outcome. As a result, there is a growing emphasis on researching the effects of human personalities and adding the results to the simulations to make them more realistic. This research investigated the possibility of incorporating personality factors into the crowd simulation model. The first part of this study explored the extraction of quantitative crowd motion from videos and developed a method to compare real video with the simulation output video. Several open source programs were examined and modified to obtain optical flow measurements from real videos captured at sporting events. Optical flow measurements provide information such as crowd density, average velocity with which individuals move in the crowd, as well as other parameters. These quantifiable optical flow calculations provided a strong method for comparing simulation results with those obtained from video footage captured in real life situations. The second part of the research focused on the incorporation of the personality factors into the crowd simulation. Existing crowd models such as HelbingU-Molnár-Farkas-Vicsek (HMFV) do not take individual personality factors into account. The most common approach employed by psychologists for studying personality traits is the Big Five factors or dimensions of personality (NEO: Neuroticism, Extroversion, Openness, Agreeableness and Conscientiousness). iii In this research forces related to the personality factors were incorporated into the crowd simulation models. The NEO-based forces were incorporated into an existing HMFV simulated implemented in the MASON simulation framework. The simulation results were validated using the quantification procedures developed in the first phase. This research reports on a major expansion of a simulation of pedestrian motion based on the model (HMFV) by Helbing, D., I. J. Farkas, P. Molnár, and T. Vicsek (2002). Example of actual behavior such as a crowd exiting church after service were simulated using NEO-based forces and show a striking resemblance to actual behavior as rated by behavior scientists.Ph.D.
Other
Engineering and Computer Science
Modeling and Simulation PhD
Books on the topic "Crown fire":
1
Annandale, David. Crown fire. Winnipeg: Ravenstone, 2003.
2
Tyers, Kathy. Crown of fire. Minneapolis, Minn: Bethany House Publishers, 2000.
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Greenwood, Ed. Crown of fire. Renton, WA: Wizards of the Coast, 2002.
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Greenwood, Ed. Crown of fire. Lake Geneva, WI: TSR, 1994.
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Parshall, Craig. Crown of fire. Eugene, Or: Harvest House Publishers, 2005.
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Greenwood, Ed. Crown of fire. Lake Geneva, Wisc: TSR, 1994.
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Property Advisers to the Civil Estate., ed. CFS[Crown Fire Standards]. London: PACE, 1997.
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Scott, Joe H. Assessing crown fire potential by linking models of surface and crown fire behavior. [Fort Collins, CO]: U.S. Dept. of Agriculture, Forest Service, Rocky Mountain Research Station, 2001.
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Scott, Joe H. Assessing crown fire potential by linking models of surface and crown fire behavior. [Fort Collins, CO]: U.S. Dept. of Agriculture, Forest Service, Rocky Mountain Research Station, 2001.
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Wright, N. T. The crown and the fire. London: SPCK, 1992.
Book chapters on the topic "Crown fire":
1
Xanthopoulos, Gavriil, and Miltiadis Athanasiou. "Crown Fire." In Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires, 1–15. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-319-51727-8_13-1.
2
Xanthopoulos, Gavriil, and Miltiadis Athanasiou. "Crown Fire." In Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires, 183–97. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-52090-2_13.
3
Perminov, Valeriy. "Numerical Solution of the Crown Forest Fires Spread Taking into Account Fire Barriers and Breaks." In Recent Developments in the Field of Non-Destructive Testing, Safety and Materials Science, 155–64. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99060-2_14.
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Karabyn, Oksana, Olga Smotr, Andrij Kuzyk, Igor Malets, and Vasy Karabyn. "Mathematical and Computer Model of the Tree Crown Ignition Process from a Mobile Grassroots Fire." In Lecture Notes in Data Engineering, Computational Intelligence, and Decision Making, 148–59. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-16203-9_9.
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Alexander, Martin E., Miguel G. Cruz, and Stephen W. Taylor. "Crown Scorch Height." In Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires, 1–7. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-51727-8_72-1.
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Alexander, Martin E., Miguel G. Cruz, and Stephen W. Taylor. "Crown Scorch Height." In Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires, 197–201. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-52090-2_72.
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Weise, David R., Jeanette Cobian-Iñiguez, and Marko Princevac. "Surface to Crown Transition." In Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires, 1–5. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-51727-8_24-1.
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Weise, David R., Jeanette Cobian-Iñiguez, and Marko Princevac. "Surface to Crown Transition." In Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires, 988–92. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-52090-2_24.
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Guijt, C. B., S. Verhoeven, and J. M. Greer. "Bonded repairs for C-5A fuselage crown cracking." In Fibre Metal Laminates, 477–97. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0995-9_31.
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Grishin, A. M. "Interaction of Shock Waves with Tree Crowns and the Front of Crown Forest Fires." In Shock Waves @ Marseille III, 411–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-642-78835-2_70.
Conference papers on the topic "Crown fire":
1
Perminov, Valeriy. "Mathematical Modeling of Crown Forest Fire Initiation and Spread." In 2009 International Conference on Computational Intelligence, Modelling and Simulation. IEEE, 2009. http://dx.doi.org/10.1109/cssim.2009.56.
2
Konovalov, V., J. L. Dupuy, F. Pimont, D. Morvan, and R. R. Linn. "Assessment of the plume theory predictions of crown scorch or crown fire initiation using transport models." In CMEM 2009. Southampton, UK: WIT Press, 2009. http://dx.doi.org/10.2495/cmem090531.
3
Dahale, Ambarish R., Selina Dover, Babak Shotorban, and Shankar Mahalingam. "Effects of Crown Fuel Bulk Density Distribution and Thermophoresis of Soot Particles on Wildland Fires." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62324.
Abstract:
The roles of two physical effects in wildfire are explored through simulations in this study. They are the spatial variation of the bulk density of crown fuel and the thermophoresis forces acting on the produced soot particles. The spatial variation of crown fuel bulk density is modeled as a function of shrub height. This function is available from experimental measurements carried out on Chamise, as crown fuel, in a previous study. In the current study, it is shown that flame spread rate and crown fire initiation are two global parameters considerably affected when the spatial variation of the bulk density is taken into account. Also, it is indicated that thermophoresis forces on soot particles have a significant impact on the evolution of solid- and gas-phase temperature in the upper region of crown fuel; however, other fire propagation characteristics are not considerably affected by these forces. In the simulations, turbulence is modeled with the large eddy simulation and radiation is modeled with the discrete ordinate method. Mass, momentum, and energy transfer between gas and solid-fuel phases are modeled through coupling terms.
4
Perminov, Valeriy, and Elina Soprunenko. "Numerical solution of crown forest fire initiation and spread problem." In 2016 11th International Forum on Strategic Technology (IFOST). IEEE, 2016. http://dx.doi.org/10.1109/ifost.2016.7884279.
5
Li, Yanxi, Gengke Lai, and Xingwen Quan. "A Physical Method for Crown Foliage Fuel Load Retrieval from Landsat Data: Toward Crown Fire Danger Assessment." In IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium. IEEE, 2022. http://dx.doi.org/10.1109/igarss46834.2022.9883232.
6
Pacaldo, Renato S., Miraç Aydın, and Randell Keith Amarille. "Soil CO2 Effluxes in Post-fire and Undisturbed Pinus nigra Forests: A Soil Moisture Manipulation Study." In 3rd International Congress on Engineering and Life Science. Prensip Publishing, 2023. http://dx.doi.org/10.61326/icelis.2023.41.
Abstract:
Climate change impacts are driving hydrological extremes and frequent occurrences of forest fires. Whether these impacts result in dramatic changes in the soil CO2 efflux (FCO2) remains poorly understood. This study seeks to understand the changes in the soil FCO2 in recently burned forest (post-fire) and an undisturbed black pine (Pinus nigra, Arnold) forest in Türkiye. A field experiment in a three-way factorial randomized complete block design experiment was established with four replications and three factors; shaded (west) and exposed (east), types of forest fires (surface, crown, and control) and soil moisture regimes (dry, wet, and control). A dynamic survey chamber soil respiration machinery (LI-8100A) was employed to measure simultaneously the soil Fco2, the soil temperature, and the soil moisture for a total duration of one-year. The soil FCO2 showed significant differences among treatments (p<0.0001), time (p<0.0001), and moisture regimes (p<0.0001), but not with the interaction effects between treatment and time (p = 0.0058), aspects (p = 0.95410), and types of forest fires (p = 0.0059). A dry soil in the crown fire site situated in the exposed aspect exhibited a significantly different and lowest soil FCO2 compared to other treatments. No statistically significant differences in the FCO2 in the wet soil were detected among treatments. The soil and air temperatures showed a strongly positive correlation (r = 0.78), suggesting that a near-surface air temperature provides a good approximation of the soil temperature. This piece of information is a vital input for the projection of future trajectory of soil CO2 emissions and conservation of C stocks in the forest fire and undisturbed forests.
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Schreuder, M. D., M. D. Schaaf, and V. Sandberg. "Evaluation of the FCCS crown fire potential equations in Aleppo pine (Pinus halepensis Mill.) stands in Greece." In FOREST FIRES 2010. Southampton, UK: WIT Press, 2010. http://dx.doi.org/10.2495/fiva100231.
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Pedes, Fabrizio, Bachisio Arca, Pierpaolo Duce, Michele Salis, Andrea Ventura, and Marcello Casula. "Enhancement of the Web-Based Wildfire Simulator for Wind Intensity Model and Crown Fire Modeling." In ICFBR 2022. Basel Switzerland: MDPI, 2022. http://dx.doi.org/10.3390/environsciproc2022017072.
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Platonov, Aleksey, A. Popov, Svetlana Snegireva, and Ekaterina Kantieva. "CHANGE IN THE HYGROSCOPICITY OF PINE CORE WOOD IN A TREE TRUNK DAMAGED BY FIRE." In Modern machines, equipment and IT solutions for industrial complex: theory and practice. FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov, 2021. http://dx.doi.org/10.34220/mmeitsic2021_274-278.
Abstract:
Fires have a significant impact on the structure and physical and mechanical properties of wood. The degree of this effect depends on the type of fire, its intensity and the duration of exposure to high temperature. The greatest impact on the wood occurs with a strong grassroots and general top fire. Gorenje fire is characterized by a high intensity of burning of forest floor and undergrowth, as well as the crown of trees. The effect of the high temperature of the fire on the tree trunk is different. As a result of the destruction of wood, there is a partial blocking of hydroxyl groups in the cellulose molecules and leads to a decrease in the hygroscopicity limit of wood. Of great practical interest is the change in the hygroscopicity of wood damaged by fire. The aim of this study is to determine the changes in the hygroscopicity of the core wood of Scots pine (Pinus sylvestris L.)after damage by a strong grassroots and general high-level fire. The studies were carried out on wood growing on the territory of the UOL in the Voronezh region, on samples of pine core wood cut from the clump, middle and apex parts of the trunk. It was experimentally established that the greatest decrease in the hygroscopicity of pine core wood occurred in the left part of the trunk, and the smallest in the middle part, after fire damage.
10
MIEZĪTE, Olga, Jeļena RŪBA, Lāsma FREIMANE, Imants LIEPA, and Edgars DUBROVSKIS. "THE HEALTH STATUS AND NATURAL REGENERATION OF PINUS SYLVESTRIS L. AFTER THE SURFACE FIRE IN VACCINIOSA FOREST TYPE IN LATVIA." In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.100.
Abstract:
From abiotic factors the most effecting influence on forest ecosystems has fire. Two years after surface fire in the pine stands growing in Vacciniosa forest type. Two PL (hereinafter PL) were installed in medium-aged (49 years old, 2.3 ha) and two PLs - in maturing (96 years old, 2.5 ha) stands. In each PL (20x20 m), the numbering of the trees was carried out and their placement was fixed, as well as the diameter, height and height of the green crown were measured. The sanitary condition of each tree was evaluated. For registration of one-year and two-year seedlings in each sample plot 25 sampling units (1 m2) were used. The similar sampling units were used for evaluation of ground cover (5 in each PL diagonally arranged), the obtained samples were weighed. The purpose of the study was to analyze the health status and natural regeneration of P.sylvestris after the surface fire. The ground vegetation was completely burned out in the medium-aged stand, but in the maturing stand both ground vegetation and organic layer - mosaically. The average burning height of trees in the medium-aged forest stand was 0.6±0.64 m, in the maturing stand - at 2.3±0.34 m. The natural regeneration was not detected in the first year after surface fire in the medium-aged forest (only 58800 one-year seedlings were recorded at the second year after fire), while in the maturing stand it was at this time (46600 one-year and 14200 two-year seedlings). Insect damage and cracked bark was not detected.
Reports on the topic "Crown fire":
1
Scott, Joe H., and Elizabeth D. Reinhardt. Assessing crown fire potential by linking models of surface and crown fire behavior. Ft. Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2001. http://dx.doi.org/10.2737/rmrs-rp-29.
2
Scott, Joe H. Comparison of crown fire modeling systems used in three fire management applications. Ft. Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2006. http://dx.doi.org/10.2737/rmrs-rp-58.
3
Andrews, Patricia L., Faith Ann Heinsch, and Luke Schelvan. How to generate and interpret fire characteristics charts for surface and crown fire behavior. Ft. Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, 2011. http://dx.doi.org/10.2737/rmrs-gtr-253.
4
Fiedler, Carl E., Charles E. Keegan, Christopher W. Woodall, and Todd A. Morgan. A strategic assessment of crown fire hazard in Montana: potential effectiveness and costs of hazard reduction treatments. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 2004. http://dx.doi.org/10.2737/pnw-gtr-622.
5
Rothermel, Richard C. Predicting behavior and size of crown fires in the northern Rocky Mountains. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, 1991. http://dx.doi.org/10.2737/int-rp-438.
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Mason, Richard R., Donald W. Scott, and H. Gene Paul. Forecasting outbreaks of the Douglas-fir tussock moth from lower crown cocoon samples. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 1993. http://dx.doi.org/10.2737/pnw-rp-460.
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Snell, J. A. Kendall, and Timothy A. Max. Estimating the weight of crown segments for old-growth Douglas-fir and western hemlock. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Forest and Range Experiment Station, 1985. http://dx.doi.org/10.2737/pnw-rp-329.
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Maffioli, Alessandro, and Bronwyn H. Hall. Evaluating the Impact of Technology Development Funds in Emerging Economies: Evidence from Latin-America. Inter-American Development Bank, January 2008. http://dx.doi.org/10.18235/0011145.
Abstract:
This working paper surveys impact evaluations of government Technology Development Funds (TDFs) in Argentina, Brazil, Chile and Panama. All the evaluations were done at the recipient (firm) level using data from innovation surveys, industrial surveys, and administrative records of the granting units, together with quasi-experimental econometric techniques to minimize the effects of any selection bias. The surveyed evaluations considered four levels of potential impact: R&D input additionality, behavioural additionality, increases in innovative output, and improvements in performance. The evidence suggests that TDFs do not crowd out private investment and that they positively affect R&D intensity. In addition, participation in TDFs induces a more proactive attitude of beneficiary firms towards innovation activities.
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Ward, Kimiora. Sierra Nevada Network white pine monitoring: 2022 annual report. National Park Service, 2023. http://dx.doi.org/10.36967/2301003.
Abstract:
Five-needle white pines (Family Pinaceae, Genus Pinus, Subgenus Strobus), and in particular whitebark pine (Pinus albicaulis), limber pine (P. flexilis), and foxtail pine (P. balfouriana) are foundation species in upper subalpine and treeline forests of several National Park Service Pacific West Region parks, including Sequoia and Kings Canyon National Parks (SEKI) and Yosemite National Park (YOSE). The Sierra Nevada Network Inventory & Monitoring Program, in collaboration with the Klamath Network, Upper Columbia Basin Network, and Mojave Desert Network have implemented a joint long-term monitoring protocol to assess the current status and future trends in high elevation white pine communities. Key demographic parameters within white pine forest communities will be estimated by monitoring individual trees within permanent plots through time. This report documents the results of the 2022 field season, which was the ninth year of monitoring in SEKI and YOSE. The 2021 goal was to complete the first full measure of the third of three rotating panels (Panel 3) for each species-park population: YOSE-whitebark pine, SEKI-whitebark pine, and SEKI-foxtail pine. Each panel consists of 12 permanent 50 x 50 m (2,500 m2) plots that were randomly selected for each of the three populations. The full sampling array thus includes a total of 36 whitebark pine plots in YOSE, 36 whitebark pine plots in SEKI, and 36 foxtail pine plots in SEKI. Data from plot surveys will be used to characterize white pine forest community dynamics in SEKI and YOSE, including changes in tree species composition, forest structure, forest health, and demographics. Partial measures of Panel 3 were completed in 2017 (11 plots) in Yosemite whitebark pine, in 2017 (9 plots) in SEKI whitebark pine, and in 2014 (7 plots) and 2017-2018 (8, 1 plots) in foxtail pine. In 2022, the first full measure of all Panel 3 plots (and 2nd or 3rd remeasure of most plots) was successfully completed, and installation was completed on four of these plots in SEKI whitebark pine and two in foxtail pine. In total, the crew visited 36 sites during the 2022 field season, all from Panel 3. Within the 36 completed Panel 1 plots, a total of 6,398 trees were measured. Species composition, forest structure, and factors affecting tree health and reproduction including incidence and severity of white pine blister rust (Cronartium ribicola) infection, mountain pine beetle (Dendroctonus ponderosae) infestation, dwarf mistletoe (Arceuthobium spp.) infection, canopy kill, and female cone production were recorded. During the 2022 field season crews continued to count the total number of mature cones per tree for whitebark and foxtail pine, use crown condition codes to assess crown health, and tag individual seedlings to be tracked through time. All three of these procedures started in 2017 and are to be evaluated by each of the three participating networks over several years, to determine whether they should become permanent changes to the monitoring protocol. In YOSE, all 12 Panel 3 whitebark pine plots were measured. A total of 2,720 trees were sampled, which included 977 live whitebark pine trees and 1,605 other live conifers. An additional 135 trees (including 26 whitebark) were recorded as dead. The average number of live whitebark pine trees per plot was 81 (SD = 94). White pine blister rust (WPBR) aecia were observed on five whitebark pine in one plot in YOSE in 2022, and no trees in any plot had inactive cankers showing three or more indicators of WPBR. WPBR had previously been documented in this plot, so the number of plots where rust has ever been observed in Yosemite remains unchanged at six. However, an infection documented in plot 42 in 2021 was not observed again when the plot was resampled in 2022, so it is possible this number should be five. Mountain pine beetle activity was observed on one live whitebark pine and three live and one dead lodgepole pine in YOSE in 2022. Despite documentation of many stands impacted by beetle attack in the field crew notes, the quantified rate of MPB attack was lower than in 2021. Twenty-one percent of live whitebark pine trees produced female cones. Cone-bearing trees averaged 7 (SD = 10) cones/tree. Whitebark pine seedling density averaged 80 (SD = 152) seedlings per hectare. The largest number of whitebark pine seedlings found in a plot was 51 and five of the twelve plots contained whitebark seedlings. All 12 Panel 3 SEKI whitebark pine plots were measured in 2022, and installation was completed on four of these, so this Panel is now fully installed. Within these plots, 2,179 live whitebark pine, 10 live foxtail pine, and 297 other live conifers were sampled (including 5 live western white pine). The average number of live whitebark pine trees per plot was 181 (SD = 125). Although the crew observed white pine blister rust in seven SEKI whitebark Panel 3 plots, no active cankers (aecia) were observed, and no trees displayed 3 of 5 indicators, so no infections were quantified. Mountain pine beetle activity was observed in 18 live and 23 dead whitebark pine and 1 live and one dead lodgepole pine within three plots in SEKI. Dwarf mistletoe was not encountered. Seven percent of live whitebark pine trees produced female cones. Cone-bearing trees averaged 3.7 (SD = 3.6) cones/tree. Whitebark seedling regeneration averaged 700 (SD = 752) seedlings per hectare. The largest number of whitebark seedlings found in a plot was 19, and two of the 12 plots did not contain any whitebark seedlings. In the foxtail pine Panel 3, all 12 plots were measured in 2022, and installation was completed on two of these, so installation of the panel is now complete. Within these plots we measured 309 live foxtail pine, 302 live whitebark pine, and 380 other live conifers, including four live western white pine. An additional 112 dead or recently dead trees and 22 unidentified snags were also measured, 19 of which were foxtail pine. The average number of foxtail pine trees per plot was 26 (SD = 26). No signs of blister rust infection or mistletoe were observed on foxtail pine. Mountain pine beetle activity was observed on one dead foxtail pine, one live whitebark pine, and seven live and one dead lodgepole pines within four plots. Sixty-two percent of the foxtail pine trees produced female cones. Cone-bearing trees averaged 33 (SD = 53) cones/tree. Seven foxtail pine seedlings were recorded within five plots, resulting in an estimated 72 (SD = 98) seedlings per hectare. Eight whitebark pine seedlings and three lodgepole pine seedlings were also found within three additional plots.
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Cytryn, E., Sean F. Brady, and O. Frenkel. Cutting edge culture independent pipeline for detection of novel anti-fungal plant protection compounds in suppressive soils. Israel: United States-Israel Binational Agricultural Research and Development Fund, 2022. http://dx.doi.org/10.32747/2022.8134142.bard.
Abstract:
Fusarium oxysporum spp. causes Panama disease in bananas and crown and root rot in an array of vegetables and field crops, but increased regulations have restricted the use of many conventional chemical pesticides, and there are a limited number of commercially available products effective against them. The soil microbiome represents a largely untapped reservoir of secondary metabolites that can potentially antagonize fungal pathogens. However, most soil bacteria cannot be cultivated using conventional techniques and therefore most of these compounds remain unexplored. The overall goal of this two-year project was to extract and characterize novel secondary metabolites from "unculturable" soil microbiomes that antagonize Fusarium and other fungal plant pathogens. Initially, the Cytryn lab at the Volcani Institute (ARO) identified candidate biosynthetic gene clusters (BGCs) encoding for potentially novel antifungal compounds (specifically non-ribosomal peptides and polyketides) in soil and plant root microbiomes using cutting-edge metagenomic platforms. Next, the Brady lab at Rockefeller University (RU) screened archived soil metagenomic cosmid libraries for these BGCs, and heterologously expressed them in suitable hosts. Finally, the Frenkel and Cytryn labs at ARO assessed the capacity of these heterologous expressed strains to antagonize Fusarium and other fungal plant pathogens. Initially tomato and lettuce were analyzed, and subsequently roots of cucumbers grown in suppressive (biochar amended) soils were targeted. We found that the composition of tomato and lettuce root BGCs are similar to each other, but significantly different from adjacent bulk soil, indicating that root bacteria possess specific secondary metabolites that are potentially associated with rhizosphere competence. BGC linked to known metabolites included various antimicrobial, (e.g., streptazone E, sessilin), antifungal (heat-stable antifungal factor- HSAF, II and ECO-02301), and insecticidal (melingmycin, orfamide A) compounds. However, over 90% of the identified BGCs were moderately to significantly different from those encoding for characterized secondary metabolites, highlighting the profusion of potentially novel secondary metabolites in both root and soil environments. Novel BGCs that were abundant in roots and remotely resembled those of antifungal compounds were transferred to RU for subsequent screening and five were identified in RU soil metagenomic cosmid libraries. Two of these clusters (BARD-1711 BARD-B481) were heterologously-expressed in a Streptomyces albus J1074 strain, and transferred to ARO. The strain harboring BARAD-B481 was found to antagonize Fusarium significantly more than the host strain, indicating that this BGCs product has antifungal activity. Future studies will need to work on chemically characterizing the BARAD-B481 BGC and progress with the above described pipeline for other interesting BGCs.