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1
Mondal, Nandita, und Raman Sukumar. „Characterising weather patterns associated with fire in a seasonally dry tropical forest in southern India“. International Journal of Wildland Fire 23, Nr. 2 (2014): 196. http://dx.doi.org/10.1071/wf13002.
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Anthropogenic fires in seasonally dry tropical forests are a regular occurrence during the dry season. Forest managers in India, who presently follow a fire suppression policy in such forests, would benefit from a system of assessing the potential risk to fire on a particular day. We examined the relationship between weather variables (seasonal rainfall, relative humidity, temperature) and days of fire during the dry seasons of 2004–2010, based on MODIS fire incident data in the seasonally dry tropical forests of Mudumalai in the Western Ghats, southern India. Logistic regression analysis showed that high probabilities of a fire day, indicating successful ignition of litter and grass fuel on the forest floor, were associated with low levels of early dry season rainfall, low daily average relative humidity and high daily average temperatures. These weather conditions are representative of low moisture levels of fine fuels, suggesting that the occurrence of fire is moderated by environmental conditions that reduce the flammability of fine fuels in the dry tropics. We propose a quantitative framework for assessing risk of a fire day to assist forest managers in anticipating fire occurrences in this seasonally dry tropical forest, and possibly for those across South Asia.
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Kovalyshyn, V., V. Marych, B. Gusar, V. Navalianyi und Ya Fedyuk. „JUSITFICATION OF DRY CHEMICAL POWDERS TESTING PROCEDURE“. Fire Safety, Nr. 33 (03.03.2019): 53–59. http://dx.doi.org/10.32447/20786662.33.2018.07.
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The analysis of the problem of extinguishing fires of magnesium and its alloys is carried out. The urgency of studying the problem is confirmed by the fact that during the extinguishing of class D fires there are factors that can complicate the quenching process. Often, these metals actively react with water, which leads to an even greater spread of the fire and even an explosion. Therefore, special fire extinguishers, which have passed the proper test, are more effective in locating the fire and prevent the burning of the powder to form the "tongues" of the flame. In Ukraine, there is no method for testing the effectiveness of fire extinguishants of special purpose for the extinguishing of class D fires. The normative documents have been analyzed, which specify the procedures for testing extinguishing fire-extinguishing special-purpose fire extinguishing class D. Specifically: the methods are described in the international standard ISO 7165: 2017 «Fire fighting – Portable fire extinguishers – Performance and construction» and GOST 53280.5-2009 Fire fighting systems automatic. Extinguishing agents.
Both methods have a number of shortcomings that need to be addressed when creating a Ukrainian fire test method for extinguishing fire extinguishing class D, namely: the dimensions of the metal frame made of sheet steel with a side (500 ± 10) mm, height (150 ± 5) mm for testing with magnesium chips are small; Not specified quantity of gasoline necessary for the rise of magnesium; The gas or oxygen torch used to dissolve magnesium does not provide full-value combustion throughout the area, but only creates separate cells of ignition.
A draft methodology has been developed that determines the fire-extinguishing efficiency of powdered powders used in Ukraine. The required amount of fuel for burning magnesium and its alloys is determined. It was ascertained that for the firing of magnesium chips it is necessary to use at least 127 grams of gasoline of the mark A 92.
Key words: test method, fire extinguishers of special purpose, extinguishing of fires of magnesium alloys
3
Wanthongchai, Kobsak, Johann G. Goldammer und Jürgen Bauhus. „Effects of fire frequency on prescribed fire behaviour and soil temperatures in dry dipterocarp forests“. International Journal of Wildland Fire 20, Nr. 1 (2011): 35. http://dx.doi.org/10.1071/wf08098.
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This study investigated how fire frequencies and fuel loads influence fire behaviour and soil heating in dry dipterocarp forests of the Huai Kha Khaeng Wildlife Sanctuary, Thailand. Fire behaviour and soil temperatures during burning were measured on a series of plots with different past fire frequencies ranging from unburned control, to rarely, infrequently and frequently burned, representing fire occurrences in 0, 1, 2 and 7 out of the past 10 years respectively. The pre-burning loads of fine fuel including grasses, herbs, shrubs, seedlings, saplings and litters increased with the length of the previous fire-free interval. The rate of spread, flame height, fireline intensity and maximum soil temperatures at any soil depths were not significantly different between the past burning regimes, so fires were classed as low-intensity and low-severity surface fire. The longest duration of heating with temperatures >60°C at ground level occurred at the rarely burned site (~14 min), followed by the infrequently burned site (~12 min) and the frequently burned site (~8 min). However, the duration of heating above any given critical temperature threshold at 2- and 5-cm soil depths was less than 1 min across all regimes. From a fuel management perspective, there does not appear to be a need to carry out prescribed burns more frequently than every 6–7 years, because fine fuel loads did not continue to accumulate substantially beyond 7 years after a fire.
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Perry, Justin J., Garry D. Cook, Erin Graham, C. P. (Mick) Meyer, Helen T. Murphy und Jeremy VanDerWal. „Regional seasonality of fire size and fire weather conditions across Australia's northern savanna“. International Journal of Wildland Fire 29, Nr. 1 (2020): 1. http://dx.doi.org/10.1071/wf19031.
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Australia’s northern savannas have among the highest fire frequencies in the world. The climate is monsoonal, with a long, dry season of up to 9 months, during which most fires occur. The Australian Government’s Emissions Reduction Fund allows land managers to generate carbon credits by abating the direct emissions of CO2 equivalent gases via prescribed burning that shifts the fire regime from predominantly large, high-intensity late dry season fires to a more benign, early dry season fire regime. However, the Australian savannas are vast and there is significant variation in weather conditions and seasonality, which is likely to result in spatial and temporal variations in the commencement and length of late dry season conditions. Here, we assess the temporal and spatial consistency of the commencement of late dry season conditions, defined as those months that maximise fire size and where the most extreme fire weather conditions exist. The results demonstrate that significant yearly, seasonal and spatial variations in fire size and fire weather conditions exist, both within and between bioregions. The effective start of late dry season conditions, as defined by those months that maximise fire size and where the most extreme fire weather variables exist, is variable across the savannas.
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Srock, Alan, Joseph Charney, Brian Potter und Scott Goodrick. „The Hot-Dry-Windy Index: A New Fire Weather Index“. Atmosphere 9, Nr. 7 (19.07.2018): 279. http://dx.doi.org/10.3390/atmos9070279.
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Fire weather indices are commonly used by fire weather forecasters to predict when weather conditions will make a wildland fire difficult to manage. Complex interactions at multiple scales between fire, fuels, topography, and weather make these predictions extremely difficult. We define a new fire weather index called the Hot-Dry-Windy Index (HDW). HDW uses the basic science of how the atmosphere can affect a fire to define the meteorological variables that can be predicted at synoptic-and meso-alpha-scales that govern the potential for the atmosphere to affect a fire. The new index is formulated to account for meteorological conditions both at the Earth’s surface and in a 500-m layer just above the surface. HDW is defined and then compared with the Haines Index (HI) for four historical fires. The Climate Forecast System Reanalysis (CFSR) is used to provide the meteorological data for calculating the indices. Our results indicate that HDW can identify days on which synoptic-and meso-alpha-scale weather processes can contribute to especially dangerous fire behavior. HDW is shown to perform better than the HI for each of the four historical fires. Additionally, since HDW is based on the meteorological variables that govern the potential for the atmosphere to affect a fire, it is possible to speculate on why HDW would be more or less effective based on the conditions that prevail in a given fire case. The HI, in contrast, does not have a physical basis, which makes speculation on why it works or does not work difficult because the mechanisms are not clear.
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Braithwaite, Richard W. „Effects of fire regimes on lizards in the wet-dry tropics of Australia“. Journal of Tropical Ecology 3, Nr. 3 (August 1987): 265–75. http://dx.doi.org/10.1017/s0266467400002145.
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ABSTRACTA quantitative analysis of the effect of fire regime on the abundance of common lizard species and genera and the species richness of two lizard groups in Kakadu National Park (12° S) is presented. A surprising range of relationships between species abundance and components of fire regimes was revealed. Carlia amax, Heteronotia binoei and Carlia gracilis appear to be fire-sensitive, Diporiphora bilineata and Carlia triacantha are favoured by early hot fires, Cryptoblepharus plagiocephalus seems relatively unaffected, Carlia foliorum seems very tolerant of fires, while Ctenotus and Sphenomorphus spp. are favoured by low intensity, patchy fires with high intensity spots.Lizard species experiencing the high-frequency fire regimes of the savannas and dry forests of the Australian wet-dry tropics are not able to select habitat at different stages of regeneration after fire but select habitat produced by fires of different types. The implication for management is that no one fire regime is optimal for the fauna as a whole. A range of fire regimes within a park should be maintained in order to retain the whole fauna.
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Oliveira, Sofia L. J., Stefan W. Maier, José M. C. Pereira und Jeremy Russell-Smith. „Seasonal differences in fire activity and intensity in tropical savannas of northern Australia using satellite measurements of fire radiative power“. International Journal of Wildland Fire 24, Nr. 2 (2015): 249. http://dx.doi.org/10.1071/wf13201.
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Earth observation sensors play an important role in quantifying the energy released by fires and capturing their spatial and temporal dynamics. Using estimates of MODIS-derived fire radiative power (FRP) we characterised bushfire activity and intensity in tropical savannas of northern Australia, by season and vegetation type, over the period 2004–2012. Our results indicate that fire activity was highest in the Northern Territory and lowest in Queensland. Mean daily number of fire detections was almost twice as high in the late dry season (August–November) compared to the early dry season (May–July). Fire season was bimodal with fire activity peaks in May and October. Median fire intensity was lower for early dry season fires (29 MW) than late dry season fires (56 MW), and was positively correlated with the number of fire detections. Vegetation types with sparse canopy structure showed lower fire activity and higher intensity. Remote sensing of FRP provides frequent estimates of fire intensity over broad areas, allowing the comparison of this key fire behaviour metric across ecosystems and throughout the fire season. FRP estimates may also be used to draw inferences regarding fire effects, once the complexity and ecosystem-specificity of the relationships between fire intensity and fire severity is acknowledged.
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Prior, Lynda D., Grant J. Williamson und David M. J. S. Bowman. „Impact of high-severity fire in a Tasmanian dry eucalypt forest“. Australian Journal of Botany 64, Nr. 3 (2016): 193. http://dx.doi.org/10.1071/bt15259.
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Dry eucalypt forests are believed to be highly fire tolerant, but their response to fire is not well quantified. We measured the effect of high-severity fires in dry eucalypt forest in the Tasmanian Midlands, the driest region on the island. We compared stand structures and fuel loads in long-unburnt (>15 years since fire) and recently burnt (<5 years since fire) sites that had been completely defoliated. Even in unburnt plots, 37% of eucalypt stems and 56% of acacia stems ≥5 cm in diameter were dead, possibly because of antecedent drought. The density of live eucalypt stems was 37% lower overall in burnt than in unburnt plots, compared with 78% lower for acacias. Whole-plant mortality caused by fire was estimated at 25% for eucalypt trees and 33% for acacias. Fire stimulated establishment of both eucalypt and acacia seedlings, although some seedlings and saplings were present in long-unburnt plots. The present study confirmed that eucalypts in dry forests are more tolerant of fire than the obligate seeder eucalypts in wet forests. However, there were few live mature stems remaining in some burnt plots, suggesting that dry eucalypt forests could be vulnerable to increasingly frequent, severe fires.
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Price, Owen F., Jeremy Russell-Smith und Felicity Watt. „The influence of prescribed fire on the extent of wildfire in savanna landscapes of western Arnhem Land, Australia“. International Journal of Wildland Fire 21, Nr. 3 (2012): 297. http://dx.doi.org/10.1071/wf10079.
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Fire regimes in many north Australian savanna regions are today characterised by frequent wildfires occurring in the latter part of the 7-month dry season. A fire management program instigated from 2005 over 24 000 km2 of biodiversity-rich Western Arnhem Land aims to reduce the area and severity of late dry-season fires, and associated greenhouse gas emissions, through targeted early dry-season prescribed burning. This study used fire history mapping derived mostly from Landsat imagery over the period 1990–2009 and statistical modelling to quantify the mitigation of late dry-season wildfire through prescribed burning. From 2005, there has been a reduction in mean annual total proportion burnt (from 38 to 30%), and particularly of late dry-season fires (from 29 to 12.5%). The slope of the relationship between the proportion of early-season prescribed fire and subsequent late dry-season wildfire was ~–1. This means that imposing prescribed early dry-season burning can substantially reduce late dry-season fire area, by direct one-to-one replacement. There is some evidence that the spatially strategic program has achieved even better mitigation than this. The observed reduction in late dry-season fire without concomitant increase in overall area burnt has important ecological and greenhouse gas emissions implications. This efficient mitigation of wildfire contrasts markedly with observations reported from temperate fire-prone forested systems.
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Roos, Christopher I., und Andrew C. Scott. „A comparison of charcoal reflectance between crown and surface fire contexts in dry south-west USA forests“. International Journal of Wildland Fire 27, Nr. 6 (2018): 396. http://dx.doi.org/10.1071/wf17139.
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The historical and modern importance of crown fires in ponderosa pine and dry mixed-conifer forests of the south-west USA has been much debated. The microscopic reflectance of charcoal in polished blocks under oil shows promise as a semiquantitative proxy for fire severity using charcoal from post-fire landscapes. We measured the reflectance of 33 modern charcoal samples to evaluate (1) whether charcoal reflectance can distinguish between crown fires and surface fires in these forests; and (2) whether surface fires with masticated fuels burn with severities similar to surface fires in grass, litter and duff fuels. The charcoal analysed was primarily collected after wildland fires under two different conditions: (l) wildfires with moderate to high severity and crown fire behaviour (n = 17), and (2) prescribed fires with low to moderate severity but no crown fire behaviour (n = 16). Statistical analysis indicates that charcoal reflectance produced in crown fires significantly differs from surface fire charcoal, particularly surface fire charcoal formed in grass, duff and litter fuels. However, charcoal produced from surface fires in masticated fuels is indistinguishable from crown fire charcoal, suggesting that fires in areas that have experienced in situ mastication may have soil impacts similar to crown fires.
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Heyerdahl, Emily K., Ken Lertzman und Carmen M. Wong. „Mixed-severity fire regimes in dry forests of southern interior British Columbia, Canada“. Canadian Journal of Forest Research 42, Nr. 1 (Januar 2012): 88–98. http://dx.doi.org/10.1139/x11-160.
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Historical fire severity is poorly characterized for dry forests in the interior west of North America. We inferred a multicentury history of fire severity from tree rings in Douglas-fir ( Pseudotsuga menziesii var. glauca (Beissn.) Franco) – ponderosa pine ( Pinus ponderosa Douglas ex P. Lawson & C. Lawson) forests in the southern interior of British Columbia, Canada. In 2 ha plots distributed systematically over 1105 ha, we determined the dates of fire scars, indicators of low-severity fire, from 125 trees and inferred dates of even-aged cohorts, potential indicators of high-severity fire, from establishment dates of 1270 trees. Most (76%) of the 41 plots contained fire-scarred trees with a mean plot-composite fire scar interval of 21 years (1700–1900). Most (76%) also contained one or two cohorts. At the plot scale, we inferred that the fire regime at most plots was of mixed severity through time (66%) and at the remaining plots of low (20%), high (10%), or unknown (4%) severity through time. We suggest that across our study area, the fire regime was mixed severity over the past several centuries, with low-severity fires most common and often extensive but small, high-severity disturbances also occasionally occurred. Our results present strong evidence for the importance of mixed-severity fire regimes in which low-severity fires dominate in interior Douglas-fir – ponderosa pine forests in western Canada.
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Kovalev, O. O., A. Y. Kalinovsky und O. G. Polivanov. „DEVELOPMENT OF INDIVIDUAL ASPECTS OF CONTAINER METHOD OF FIRE EXTINGUISHING“. Fire Safety, Nr. 34 (19.07.2019): 35–42. http://dx.doi.org/10.32447/10.32447/20786662.34.2019.06.
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Currently, the creation of fundamentally new technical means of fire extinguishing and the development of new methods for delivering fire extinguishing substances to a remote distance when extinguishing complex fires is the actual scientific and technical problem. The fire fighting equipment currently used in the territorial divisions of the SES of Ukraine does not allow delivering of fire extinguishing substances at a distance of 100 m and more. Existing fire fighting equipment is designed to deliver water, aqueous solutions and foams at a distance of up to 100 meters, as well as dry chemicals at a distance of up to 70 meters. Today various researchers are developing technical means and methods for remote delivery of such fire extinguishing agents as aerosol-forming compounds, dry chemical powders, fire extinguishing freons, solid carbon dioxide and organometallic compounds. At the same time, the use of the considered fire extinguishing agents did not become widespread in the fire and rescue units due to insufficient development of technical means and methods of delivery. To solve the problem of delivering fire extinguishing substances to a remote distance while extinguishing complex fires, it was proposed to use a barrelled fire extinguishing system, which ensures high-precision delivery by throwing the containers filled with extinguishing agent directly into the combustion zone along the ballistic trajectory. The analysis of various fire extinguishing substances and compositions for use in containers showed that to achieve the highest efficiency of fire extinguishing, it is advisable to use dry chemical powders. As a result of the study of the use of dry chemical powders as container fillers, the mechanics of the fire extinguishing action of dry chemical compositions after releasing from the container by excessive pressure, created by detonation products of explosives, was investigated. A method for determining the total mass of dry chemical powder and the required number of containers filled with dry chemical powder for extinguishing class A and B fires has been developed. Keywords
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Murphy, Brett P., und Jeremy Russell-Smith. „Fire severity in a northern Australian savanna landscape: the importance of time since previous fire“. International Journal of Wildland Fire 19, Nr. 1 (2010): 46. http://dx.doi.org/10.1071/wf08202.
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Using a detailed fire history collected over a 10-year period throughout a savanna landscape in northern Australia, we have addressed the question of whether fire severity, inferred from a semiquantitative fire severity index, increases with time since previous fire. There was a clear trend of fires becoming much more severe with increasing time since previous fire. Between 1 and 5 years following a fire, the probability of a subsequent fire being classified as ‘severe’ increased from 3 to 8% for early dry-season fires, and from 21 to 43% for late dry-season fires. It was clear that the strong increase in fire severity was not confined to the first 2–3 years following the previous fire, as previously suspected. These findings highlight the difficulty of reducing both fire frequency and severity in northern Australian savanna landscapes, as they imply that a negative feedback process exists between the two; that is, reducing fire frequency is likely to increase the severity of fires that do occur.
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Harley, Grant L., Emily K. Heyerdahl, James D. Johnston und Diana L. Olson. „Riparian and adjacent upland forests burned synchronously during dry years in eastern Oregon (1650–1900 CE), USA“. International Journal of Wildland Fire 29, Nr. 7 (2020): 602. http://dx.doi.org/10.1071/wf19101.
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Riparian forests link terrestrial and freshwater communities and therefore understanding the landscape context of fire regimes in these forests is critical to fully understanding the landscape ecology. However, few direct studies of fire regimes exist for riparian forests, especially in the landscape context of adjacent upland forests or studies of long-term climate drivers of riparian forest fires. We reconstructed a low-severity fire history from tree rings in 38 1-ha riparian plots and combined them with existing fire histories from 104 adjacent upland plots to yield 2633 fire scars sampled on 454 trees. Historically (1650–1900), low-severity fires burned more frequently in upland than in riparian plots, but this difference was not significant (P=0.15). During more than half of the fire years at both sites, fires were extensive and burned synchronously in riparian and upland plots, and climate was significantly dry during these years. However, climate was not significantly dry when fires burned in only one plot type. Historically, entire riparian zones likely burned in these two study sites of the Blue Mountains during dry years. This study suggests that riparian and upland forests could be managed similarly, especially given the projected increases to fire frequency and intensity from impending climate change.
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Chen, Feng, Zhaofei Fan, Shukui Niu und Jingming Zheng. „The Influence of Precipitation and Consecutive Dry Days on Burned Areas in Yunnan Province, Southwestern China“. Advances in Meteorology 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/748923.
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Precipitation is among the more limiting meteorological factors affecting the occurrence and extent of forest fire. We examined the correlation between burned area of individual wildfires and the rainfall amounts occurring on the day of the burn and the number of consecutive dry days for a range of limiting daily rainfall amounts (0–6mm) used to define a “dry” day. Daily threshold rainfall levels that most significantly affected area burned were determined for each ecoregion in Yunnan province, a major fire-prone area, in southwestern China. Results showed that the burned area of a wildfire decreased exponentially with increasing rainfall amounts on the day of burning. Burned area was also positively correlated to the number of consecutive dry days prior to burning. The threshold rainfall value providing the highest correlation between burned area and the number of consecutive dry days prior to a burn varied between ecoregions. Consecutive dry days with rainfall less than the specified threshold predominantly affected large fires (>100 ha) rather than more frequently occurring small fires. These results will help forest managers evaluate regionalfire danger indices for forest fire prevention, particularly for catastrophic forest wildfires causing significant economic losses and threats to human life and environment.
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Wotton, B. Mike, James S. Gould, W. Lachlan McCaw, N. Phillip Cheney und Stephen W. Taylor. „Flame temperature and residence time of fires in dry eucalypt forest“. International Journal of Wildland Fire 21, Nr. 3 (2012): 270. http://dx.doi.org/10.1071/wf10127.
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Temperature profiles of flames were measured using arrays of thermocouples on towers located in experimental bushfires of varying intensity, carried out in dry eucalypt forest of different fuel age and structure. In-fire video of flame-front passage and time series data from very fine exposed thermocouples were used to estimate the duration of passage of the main flaming front in these experimental fires. Flame temperature measured at points within the flame was found to vary with height; maximum flame temperature was greater in the tall shrub fuel than in the low shrub fuel sites. A model to estimate flame temperature at any height within a flame of a specific height was developed. The maximum flame temperature observed was ~1100°C near the flame base and, when observation height was normalised by flame height, flame temperature exponentially decreased to the visible flame tip where temperatures were ~300°C. Maximum flame temperature was significantly correlated with rate of spread, fire intensity, flame height and surface fuel bulk density. Average flame-front residence time for eucalypt forest fuels was 37 s and did not vary significantly with fine fuel moisture, fuel quantity or bulk density.
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Wolfe, Brett T., Gabriel E. Saldaña Diaz und Skip J. Van Bloem. „Fire resistance in a Caribbean dry forest: inferences from the allometry of bark thickness“. Journal of Tropical Ecology 30, Nr. 2 (06.02.2014): 133–42. http://dx.doi.org/10.1017/s0266467413000904.
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Abstract:Trees’ resistance to fire-induced mortality increases with bark thickness, which varies widely among species and generally increases with stem diameter. Because dry forests are more fire-prone than wetter forests, bark may be thicker in these forests. However, where disturbances such as hurricanes suppress stem diameter, trees may not obtain fire-resistant bark thickness. In two hurricane-prone Caribbean dry-forest types in Puerto Rico—deciduous forest and scrub forest—we measured bark thickness on 472 stems of 25 species to test whether tree species obtain bark thicknesses that confer fire resistance, whether bark is thicker in the fire-prone scrub forest than in the deciduous forest, and how bark thickness in Caribbean dry forest compares with other tropical ecosystems. Only 5% of stems within a deciduous-forest stand had bark thickness that would provide < 50% probability of top-kill during low-intensity fire. In contrast, thicker-barked trees dominated the scrub forest, suggesting that fires influenced it. Compared with trees of similar diameter in other regions of the tropics, bark in Caribbean dry forest was thinner than in savanna, similar to other seasonally dry forests, and thicker than moist-to-wet forests. Dry-forest species appear to invest more in fire-resistance than species from wetter forests. However, Caribbean dry forests remain highly vulnerable to fire because the trees rarely reach large enough diameters to be fire resistant.
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Johnson, Lane, und Ellis Margolis. „Surface Fire to Crown Fire: Fire History in the Taos Valley Watersheds, New Mexico, USA“. Fire 2, Nr. 1 (14.03.2019): 14. http://dx.doi.org/10.3390/fire2010014.
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Tree-ring fire scars, tree ages, historical photographs, and historical surveys indicate that, for centuries, fire played different ecological roles across gradients of elevation, forest, and fire regimes in the Taos Valley Watersheds. Historical fire regimes collapsed across the three watersheds by 1899, leaving all sites without fire for at least 119 years. Historical photographs and quaking aspen (Populus tremuloides Michx.) ages indicate that a high-severity fire historically burned at multiple high-elevation subalpine plots in today’s Village of Taos Ski Valley, with large high-severity patches (>640 ha). Low-severity, frequent (9–29-year median interval) surface fires burned on the south aspects in nearby lower elevation dry conifer forests in all watersheds. Fires were associated with drought during the fire year. Widespread fires commonly burned synchronously in multiple watersheds during more severe drought years, preceded by wet years, including fire in all three watersheds in 1664, 1715, and 1842. In contrast, recent local “large” wildfires have only burned within single watersheds and may not be considered large in a historical context. Management to promote repeated low-severity fires and the associated open stand structures is within the historical range of variability in the dry conifer forests of these watersheds. In the high-elevation, subalpine forests, different management approaches are needed, which balance ecological and socioeconomic values while providing public safety.
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Belhadj-Khedher, Chiraz, Taoufik El-Melki und Florent Mouillot. „Saharan Hot and Dry Sirocco Winds Drive Extreme Fire Events in Mediterranean Tunisia (North Africa)“. Atmosphere 11, Nr. 6 (03.06.2020): 590. http://dx.doi.org/10.3390/atmos11060590.
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With hot and dry summers, the Mediterranean basin is affected by recurrent fires. While drought is the major driver of the seasonal and inter-annual fire distribution in its northern and mildest climate conditions, some extreme fire events are also linked to extreme winds or heat waves. The southern part of the Mediterranean basin is located at the driest range of the Mediterranean bioclimate and is influenced by Saharan atmospheric circulations, leading to extreme hot and dry episodes, called Sirocco, and potentially acting as a major contributor to fire hazard. The recently created fire database for Tunisia was used to investigate the ±10-day pre- and post-fire timeframe of daily weather conditions associated with fire events over the 1985–2006 period. Positive anomalies in minimum and maximum temperatures, negative anomalies in air relative humidity, and a preferential south-eastern wind during fire events were identified, which were characteristic of Sirocco winds. +7 °C anomalies in air temperature and −30% in relative air humidity were the critical thresholds for the most extreme fire conditions. In addition, meteorological anomalies started two days before fire events and lasted for three days after for large fires >400 ha, which suggests that the duration of the Sirocco event is linked with fire duration and final fire size. Lastly, the yearly number of intense Sirocco events better explained the inter-annual variability of burned area over the 1950–2006 period than summer drought based on Standardized Precipitation Evaporation Index (SPEI) indices.
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Castellanos, P., K. F. Boersma und G. R. van der Werf. „Satellite observations indicate substantial spatiotemporal variability in biomass burning NO<sub>x</sub> emission factors for South America“. Atmospheric Chemistry and Physics 14, Nr. 8 (17.04.2014): 3929–43. http://dx.doi.org/10.5194/acp-14-3929-2014.
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Abstract. Biomass burning is an important contributor to global total emissions of NOx (NO+NO2). Generally bottom-up fire emissions models calculate NOx emissions by multiplying fuel consumption estimates with static biome-specific emission factors, defined in units of grams of NO per kilogram of dry matter consumed. Emission factors are a significant source of uncertainty in bottom-up fire emissions modeling because relatively few observations are available to characterize the large spatial and temporal variability of burning conditions. In this paper we use NO2 tropospheric column observations from the Ozone Monitoring Instrument (OMI) from the year 2005 over South America to calculate monthly NOx emission factors for four fire types: deforestation, savanna/grassland, woodland, and agricultural waste burning. In general, the spatial patterns in NOx emission factors calculated in this work are consistent with emission factors derived from in situ measurements from the region but are more variable than published biome-specific global average emission factors widely used in bottom-up fire emissions inventories such as the Global Fire Emissions Database (GFED). Satellite-based NOx emission factors also indicate substantial temporal variability in burning conditions. Overall, we found that deforestation fires have the lowest NOx emission factors, on average 30% lower than the emission factors used in GFED v3. Agricultural fire NOx emission factors were the highest, on average a factor of 1.8 higher than GFED v3 values. For savanna, woodland, and deforestation fires, early dry season NOx emission factors were a factor of ~1.5–2 higher than late dry season emission factors. A minimum in the NOx emission factor seasonal cycle for deforestation fires occurred in August, the time period of severe drought in South America in 2005, supporting the hypothesis that prolonged dry spells may lead to an increase in the contribution of smoldering combustion from large-diameter fuels, offsetting the higher combustion efficiency of dryer fine fuels. We evaluated the OMI-derived NOx emission factors with SCIAMACHY NO2 tropospheric column observations and found improved model performance in regions dominated by fire emissions.
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Husar, B., V. Kovalyshyn, V. Marych, R. Lozynskyi und P. Pastukhov. „COMBINED EXTINGUISHING OF CLASS D, CLASS A AND CLASS B FIRES“. Fire Safety 35 (26.02.2020): 30–34. http://dx.doi.org/10.32447/20786662.35.2019.05.
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The scope of magnesium and aluminium and their alloys in industry, construction and life are expanding over time. As a rule, there are no clean fires of class D, which include combustion of magnesium, aluminium and their alloys. The problem is that the temperature of combustion of magnesium and its alloys can rise above 2800 Celsius degree. Magnesium burns even in the atmosphere of nitrogen and carbon dioxide and such fire is very difficult to extinguish. When water contacts the magnesium or other light metals, the area of fire expands.
The main purpose of this work is to study the combined extinguishing of light metals fires, Class A fires and class B fires with a special dry chemical powder and high resistance foaming agent.
The problem of extinguishing fires at objects with the using of light metals (magnesium, aluminium) and their alloys has been explored. Class D fires usually lead to class A and class B fires. They occur at high temperatures, and may cause explosions. Scenarios for the development of fires can be as follows: burning of light metals or solid combustible materials ad initium and light metal fire that requires combined extinguishing methods afterwards. Dry chemical powder formulation for extinguishing class A, B, D and and electrical installations under voltage, which includes: sodium chloride, blast furnace slag, ammophos, aerosol has been developed. Testing of this powder has been carried out in the laboratory using chips of magnesium and aluminium alloys. The combustion area in all experiments has been equal to 2.85 × 10-2 sq. m. The quality of the powder has been evaluated by the intensity of the D class fire and the extinguishing time of the B class fier. Dry chemical powder KM-2 has been tested for extinguishing fires 21B, 1A. and for magnesium alloy chips fires. Combined extinguishing tests were conducted on class D, class A and class B fires in field conditions. Method of combined extinguishing with the dry chemical powder followed by covering the entire burning area with high-expansion foam has been proposed (the fire with total area of 2.5 square meters has been extinguished for 45 s). Extinguishing methods have been tested on model fires. Safety measures for light metal extinguishing have been developed.
Conclusions: formulation for universal KM 2 dry chemical powder for extinguishing class D, A, B fires, which consists of sodium chloride, ammophos, slag, aerosil, has been developed. Successful extinguishing of class D and B fires has been carried out succesfully; technology of combined fire fighting D and A has been substantiated.
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Price, Owen F., Andrew C. Edwards und Jeremy Russell-Smith. „Efficacy of permanent firebreaks and aerial prescribed burning in western Arnhem Land, Northern Territory, Australia“. International Journal of Wildland Fire 16, Nr. 3 (2007): 295. http://dx.doi.org/10.1071/wf06039.
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We investigated the efficacy of firebreaks in the prevention of wildfires in the Arnhem Land Plateau, a vast, rugged and sparsely populated region with high biodiversity value and frequent wildfires. A total of 623 events where a fire met a permanent firebreak (cliffs, stream order, tracks and roads) in different fire seasons were compiled. Cliffs were more effective than streams at stopping fires, which were more effective than roads. Larger streams were more effective than small ones. The largest streams stop 75% of early dry season fires, but there are no firebreak types with more than 50% likelihood of stopping a late dry season fire. Geographic Information System (GIS) surfaces of the relative density of the three firebreak features in the landscape were randomly sampled and compared with the total number of fires and late dry season fires using generalised linear modelling. Several of the density variables were weakly but significantly related to fire frequency, and it appears that late dry season fires are influenced by features at a larger scale (16-km radius) than total fires (4 km). The Aerial Prescribed Burning program for 2004 was studied to identify how effective it was at stopping subsequent wildfires by dividing ignition lines into 137 5-km sections. Only 20% of sections achieved a 100% burn and where gaps occurred, a subsequent fire was 88% likely to penetrate the line. Firebreaks are not certain instruments for fire management in this area.
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Myerscough, Peter J., und Peter J. Clarke. „Burnt to blazes: landscape fires, resilience and habitat interaction in frequently burnt coastal heath“. Australian Journal of Botany 55, Nr. 2 (2007): 91. http://dx.doi.org/10.1071/bt06114.
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Four fires burned vegetation on a sand plain on a 4-km stretch of Pleistocene beach ridges between 1980–1981 and 1998. Fires of 1980–81 and 1991 burned the whole area. Those of 1994 and 1998 burned only parts of it. Cover of individual species and bare ground was scored on permanent plots at intervals between 1990 and 1996. Ordination and generalised linear model analysis of the data showed strong spatial variation between dry and wet heaths, four transects and plots within transects. This was strictly conserved through time, owing to the rapid regrowth of abundant resprouting species, most of which, after 1 year, showed little change in cover with increasing time-since-fire. Vegetation of the dry and wet heaths showed no detectable convergence or divergence in similarity with time-since-fire or variation of interval between fires. Changes with time-since-fire were found, and some change with the length of fire interval, owing to variation in cover of obligate-seeder species, which increased steadily with time up to 10 years since fire, and showed some decrease when fire interval decreased to 3.75 years. At 10 years since fire, obligate-seeder species reached ~25% of the totalled cover scores for all species, with 75% from resprouting species. Dry and wet heath were broadly similar in their general pattern of regrowth after fire, but in dry heath bare ground was more slowly covered than in wet heath, and wet heath had a higher cover of monocotyledons, especially restiads and sedges. Wet heath was more flammable than dry heath in the patchy fire of 1998. The heaths observed appeared highly resilient to recent fire regimes. Resprouting species always dominated their canopy; none of their obligate-seeding species formed a dominant overstorey canopy.
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Price, Owen, Jeremy Russell-Smith und Andrew Edwards. „Fine-scale patchiness of different fire intensities in sandstone heath vegetation in northern Australia“. International Journal of Wildland Fire 12, Nr. 2 (2003): 227. http://dx.doi.org/10.1071/wf03040.
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We assessed the extent of burning and rockiness in 3712 5 × 5 m quadrats along 9.2 km of transects sampling five different fires in sandstone heaths where contemporary fire regimes are thought to be reducing the populations of many plants. All fires were patchy, with means of 64% burnt for early dry season and 84% for late dry season fires. Rockiness was strongly related to the presence of unburned patches, and some late dry season fires leave no patches in the absence of rocks. Half of the unburned patches were 10 m or less in length and of the 83 patches identified only three were still detectable when data were amalgamated into quadrats of 500 m2. Thus, very few patches could be recognised from satellite images. The results suggest that fires are much more patchy than satellite-derived fire maps indicate. This has important implications for understanding how populations of fire sensitive plants will respond to different fire regimes.
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Sherriff, Rosemary L., und Thomas T. Veblen. „Variability in fire - climate relationships in ponderosa pine forests in the Colorado Front Range“. International Journal of Wildland Fire 17, Nr. 1 (2008): 50. http://dx.doi.org/10.1071/wf07029.
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Understanding the interactions of climate variability and wildfire has been a primary objective of recent fire history research. The present study examines the influence of El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) on fire occurrence using fire-scar evidence from 58 sites from the lower ecotone to the upper elevational limits of ponderosa pine (Pinus ponderosa) in northern Colorado. An important finding is that at low v. high elevations within the montane zone, climatic patterns conducive to years of widespread fire are different. Differences in fire–climate relationships are manifested primarily in antecedent year climate. Below ~2100 m, fires are dependent on antecedent moister conditions that favour fine fuel accumulation 2 years before dry fire years. In the upper montane zone, fires are dependent primarily on drought rather than an increase in fine fuels. Throughout the montane zone, fire is strongly linked to variations in moisture availability that in turn is linked to climate influences of ENSO, PDO and AMO. Fire occurrence is greater than expected during the phases of each index associated with drought. Regionally widespread fire years are associated with specific phase combinations of ENSO, PDO and AMO. In particular, the combination of La Niña, negative PDO and positive AMO is highly conducive to widespread fire.
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Castellanos, P., K. F. Boersma und G. R. van der Werf. „Satellite observations indicate substantial spatiotemporal variability in biomass burning NO<sub>x</sub> emission factors for South America“. Atmospheric Chemistry and Physics Discussions 13, Nr. 8 (30.08.2013): 22757–93. http://dx.doi.org/10.5194/acpd-13-22757-2013.
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Abstract. Biomass burning is an important contributor to global total emissions of NOx (NO + NO2). Generally bottom-up fire emissions models calculate NOx emissions by multiplying fuel consumption estimates with static biome specific emission factors, defined in units of grams of NO per kilogram of dry matter consumed. Emission factors are a significant source of uncertainty in bottom-up fire emissions modeling because relatively few observations are available to characterize the large spatial and temporal variability of burning conditions. In this paper we use NO2 tropospheric column observations from the Ozone Monitoring Instrument (OMI) from the year 2005 over South America to calculate monthly NOx emission factors for four fire types: deforestation, savanna/grassland, woodland, and agricultural waste burning. In general, the spatial trends in NOx emission factors calculated in this work are consistent with emission factors derived from in situ measurements from the region, but are more variable than published biome specific global average emission factors widely used in bottom up fire emissions inventories such as the Global Fire Emissions Database (GFED) v3. Satellite based NOx emission factors also indicate substantial temporal variability in burning conditions. Overall, we found that deforestation fires have the lowest NOx emission factors, on average 30 % lower than the emission factors used in GFED v3. Agricultural fire NOx emission factors were the highest, on average a factor of 2 higher than GFED v3 values. For savanna, woodland, and deforestation fires early dry season NOx emission factors were a factor of ~1.5–2.0 higher than late dry season emission factors. A minimum in the NOx emission factor seasonal cycle for deforestation fires occurred in August, the time period of severe drought in South America in 2005. Our results support the hypothesis that prolonged dry spells may lead to an increase in the contribution of smoldering combustion from large diameter fuels to total fire emissions, which would lower the overall modified combustion efficiency (MCE) and NOx emission factor, and offset the higher combustion efficiency of dryer fine fuels. We evaluated the OMI derived NOx emission factors with SCIAMACHY NO2 tropospheric column observations and found improved model performance in regions dominated by fire emissions.
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Eskelson, Bianca N. I., und Vicente J. Monleon. „Post-fire surface fuel dynamics in California forests across three burn severity classes“. International Journal of Wildland Fire 27, Nr. 2 (2018): 114. http://dx.doi.org/10.1071/wf17148.
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Forest wildfires consume fuel and are followed by post-fire fuel accumulation. This study examines post-fire surface fuel dynamics over 9 years across a wide range of conditions characteristic of California fires in dry conifer and hardwood forests. We estimated post-fire surface fuel loadings (Mgha−1) from 191 repeatedly measured United States national inventory plots in dry conifer and hardwood stands of 49 California forest wildfires and identified differences across fire severity classes – low, moderate and high. No significant change in duff load was detected within the first 9 years post-fire across all forest types and fire severities. Litter, 1-h and 10-h fuels exhibited a quadratic trend over time in dry conifer stands, peaking ~6 years after fire, whereas hardwood stands displayed a constant rate of increase in those fuel types. For 100- and 1000-h fuels, the annual rate of change was constant for dry conifer and hardwood stands with differing rates of change across fire severity classes. This study was based on an extensive, spatially balanced sample across burned dry conifer and hardwood forests of California. Therefore, the estimated patterns of fuel accumulation are generally applicable to wildfires within this population.
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Stolle, F., und E. F. Lambin. „Interprovincial and interannual differences in the causes of land-use fires in Sumatra, Indonesia“. Environmental Conservation 30, Nr. 4 (Dezember 2003): 375–87. http://dx.doi.org/10.1017/s0376892903000390.
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Despite the vast destruction caused by recent fires in Sumatra's forested areas, there have been few analyses of their spatial variability and causes. Various combinations of predisposing and land-use factors in space and time may cause fires. For each variable, fire densities were calculated to assess the spatial and temporal association between natural and cultural landscape variables and fire occurrence in four provinces in Sumatra, Indonesia for a non-dry year (1999) and a dry year (1997). This was complemented by a single multivariate logistic regression for the two years over the four provinces with fires as the dependent variable and land use and predisposing factors as independent variables. The provincial analyses showed that fires are determined by multiple, interacting factors and that these factor interactions are not the same in all provinces. In the non-dry year, the factors were only weak determinants of fires and only few determinants were common to all provinces (presence of undisturbed forests, elevation, smallholder area, land allocation to production area). In the dry year, more determinants of fires were found to be common to all provinces (presence of undisturbed forests, elevation, land allocation to production or conversion areas, presence of plantations, distance from roads). This led to the identification of pathways that increased fire probability. The first step was the allocation of land to different land-use types and stakeholders by national policies. If allocated to large-scale landowners, fires were more likely to occur in plantations, especially in the dry year. Logging concessions did not play a major role in increasing the incidence of fire. However the strongest increase in fire probability was outside the areas under use, in undisturbed forests. We conclude that areas not yet used by large-scale landowners were more prone to fire, indicating a serious threat to the remaining forests in this region.
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Нulida, E., Ya Kozak und M. Vasiliev. „THE RESEARCH OF FIRE RESISTANCE LIMIT OF THE TANK STORAGE OF PETROLEUM PRODUCTS“. Fire Safety 37 (06.01.2021): 37–43. http://dx.doi.org/10.32447/20786662.37.2020.06.
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Introduction. Statistical analysis of fires at storage, refining and transportation facilities for oil and petroleum products over the past 20 years shows that out of 200 fires, 92% of them occur in land tanks. In a fire, liquid combustion in the tank is a diffusion combustion of a jet of steam in the air. In the process of burning the liquid in the tank changes the mechanical properties of its metal wall, which affects its fire resistance duration. In the event of a fire in the tank, the drywall may be destroyed. Destruction of dry tank wall can lead to oil spills and cascading fire. Therefore, the main problem is to determine the fire duration before the destruction of the dry wall of the tank, i.e. its fire resistance.Purpose. Develop a method for determining the fire resistance of the dry wall of the storage tank of oil and petroleum products.Methods. To develop a method for determining the fire resistance of storage tank dry wall of oil and petroleum prod-ucts, it is necessary to solve the following problems:1) to determine the temperature effect on sheet material of tank dry wall on its strength;2) to obtain the dependence for determining the duration of time before the occurrence of ultimate destructive stresses of the sheet material of tank dry wall;3) to obtain the dependence for determining the time of fire resistance of tank dry wall of oil and petroleum products in the event of a fire.To solve the first problem, the temperature influence of the sheet steel used to make the tank wall on the yield strength σT was established.To solve the second problem, a dependence was obtained to determine the length of time before the occurrence of critical temperatures at which the destruction of the sheet material of tank dry wall is possible.To solve the third problem, a block diagram of the algorithm for determining the fire resistance of tank dry wall in case of fire was developed, on the basis of which a package of applications was developed.Conclusions and specific suggestions:1. The influence of the temperature of the sheet material of tank dry wall on its strength is established. The research results showed that the temperature of the tank drywall material in the range of 690-710 ºC is critical and it can lead to its destruction.2. The results of the research allowed to obtain the dependence for determining the duration of time to critical temper-atures occurrence at which the destruction of the sheet material of tank dry wall. The results of calculations for the tank RVS-5000 showed that its fire resistance varies within τv = 13…15 minutes. Of course, this value of fire resistance for tank dry wall is very small in terms of the fire extinguishing process. Therefore, it is necessary to develop and implement certain measures to increase the fire resistance of tank dry wall.3. To determine the time of fire resistance of tank dry wall storage of oil and petroleum products in the event of a fire was obtained dependence, which allows to determine the temperature T in ºC from the duration of burning the tank τ per minute, the height of the dry wall h0 in m upper edge. The research results allowed to develop a block diagram of the algorithm for solving this problem, as well as a package of applications based on it, which are written in the C # programming language.
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Нulida, E., Ya Kozak und M. Vasiliev. „THE RESEARCH OF FIRE RESISTANCE LIMIT OF THE TANK STORAGE OF PETROLEUM PRODUCTS“. Fire Safety 37 (06.01.2021): 37–43. http://dx.doi.org/10.32447/20786662.37.2020.06.
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Introduction. Statistical analysis of fires at storage, refining and transportation facilities for oil and petroleum products over the past 20 years shows that out of 200 fires, 92% of them occur in land tanks. In a fire, liquid combustion in the tank is a diffusion combustion of a jet of steam in the air. In the process of burning the liquid in the tank changes the mechanical properties of its metal wall, which affects its fire resistance duration. In the event of a fire in the tank, the drywall may be destroyed. Destruction of dry tank wall can lead to oil spills and cascading fire. Therefore, the main problem is to determine the fire duration before the destruction of the dry wall of the tank, i.e. its fire resistance.Purpose. Develop a method for determining the fire resistance of the dry wall of the storage tank of oil and petroleum products.Methods. To develop a method for determining the fire resistance of storage tank dry wall of oil and petroleum prod-ucts, it is necessary to solve the following problems:1) to determine the temperature effect on sheet material of tank dry wall on its strength;2) to obtain the dependence for determining the duration of time before the occurrence of ultimate destructive stresses of the sheet material of tank dry wall;3) to obtain the dependence for determining the time of fire resistance of tank dry wall of oil and petroleum products in the event of a fire.To solve the first problem, the temperature influence of the sheet steel used to make the tank wall on the yield strength σT was established.To solve the second problem, a dependence was obtained to determine the length of time before the occurrence of critical temperatures at which the destruction of the sheet material of tank dry wall is possible.To solve the third problem, a block diagram of the algorithm for determining the fire resistance of tank dry wall in case of fire was developed, on the basis of which a package of applications was developed.Conclusions and specific suggestions:1. The influence of the temperature of the sheet material of tank dry wall on its strength is established. The research results showed that the temperature of the tank drywall material in the range of 690-710 ºC is critical and it can lead to its destruction.2. The results of the research allowed to obtain the dependence for determining the duration of time to critical temper-atures occurrence at which the destruction of the sheet material of tank dry wall. The results of calculations for the tank RVS-5000 showed that its fire resistance varies within τv = 13…15 minutes. Of course, this value of fire resistance for tank dry wall is very small in terms of the fire extinguishing process. Therefore, it is necessary to develop and implement certain measures to increase the fire resistance of tank dry wall.3. To determine the time of fire resistance of tank dry wall storage of oil and petroleum products in the event of a fire was obtained dependence, which allows to determine the temperature T in ºC from the duration of burning the tank τ per minute, the height of the dry wall h0 in m upper edge. The research results allowed to develop a block diagram of the algorithm for solving this problem, as well as a package of applications based on it, which are written in the C # programming language.
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Russell-Smith, Jeremy, und Andrew C. Edwards. „Seasonality and fire severity in savanna landscapes of monsoonal northern Australia“. International Journal of Wildland Fire 15, Nr. 4 (2006): 541. http://dx.doi.org/10.1071/wf05111.
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Ten years of photo and associated data records from an extensive fire and vegetation effects monitoring programme established in two large north Australian National Parks were used to (1) develop a simple-to-use semiquantitative fire severity index based on observed fire impact on vegetation, particularly leaf-scorch height; and (2) explore relationships between seasonality and fire severity in different landform and vegetation types. Using a three-tiered fire severity scale, data for 719 fires recorded from 178 plots over the period 1995–2004 indicate that the great majority of early dry season (pre-August) fires were of very low severity (fire-line intensities <<1000 kW m–1), whereas fires later in the dry season were typically of substantially greater severity. Similar trends were evident for vegetation occupying all landform types. The utility and limitations of the fire severity index, and implications for ecologic, greenhouse inventory, and remote sensing applications are discussed.
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Yen, Ming-Cheng, und Tsing-Chang Chen. „On the Fire Nature of a Subtropical Maritime Island in East Asia: Taiwan“. Journal of Applied Meteorology 44, Nr. 8 (01.08.2005): 1274–75. http://dx.doi.org/10.1175/jam2278.1.
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Abstract Active wild fires over continental landmasses occur in the warm, dry summer. In contrast, in a study by Yen and Chen it was observed that the fire occurrence in Taiwan exhibits an annual variation with a peak in the cool, dry winter. Analysis of the fire-disaster reports released recently by the National Fire Administration of Taiwan shows that fire-related house damage, property loss, and human casualties, overall, exhibit annual variations in concert with the annual variation in the fire-occurrence frequency. The fire-disaster statistics support Yen and Chen’s observation of the annual variation of the fire-occurrence frequency on a subtropical maritime island.
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Bowman, D. M. J. S., Yue Zhang, Angie Walsh und R. J. Williams. „Experimental comparison of four remote sensing techniques to map tropical savanna fire-scars using Landsat-TM imagery“. International Journal of Wildland Fire 12, Nr. 4 (2003): 341. http://dx.doi.org/10.1071/wf03030.
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A landscape-scale fire experiment, conducted over two consecutive dry seasons in a large tract of tropical savanna in northern Australia, was used to evaluate four methods to map fire scars apparent on Landsat-TM imagery: (i) systematic visual; (ii) semi-automated; (iii) automated; and (iv) change detection. All of the methods showed rapid fading of the fire scars. Overall, the automated and visual methods were able to discriminate burnt areas for longer than the other methods. However, the automated method also falsely identified fire-scars on between 5 and 20% of the unburnt catchments prior to the experimental late dry season fire treatments. One cause of the fading appears related to the increased flushing of tree canopies on burnt areas, although the spatially patchy recovery within and between catchments points to the importance of other factors such as the recovery of the ground layer. It appears that Landsat-TM imagery cannot be used to reliably determine the spatial extent and timing of fires in environments with rapid post-fire recovery, such as tropical savannas, thereby limiting the utility of this data source for fine-scale ecological studies.
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Evans, Jay, und Jeremy Russell-Smith. „Delivering effective savanna fire management for defined biodiversity conservation outcomes: an Arnhem Land case study“. International Journal of Wildland Fire 29, Nr. 5 (2020): 386. http://dx.doi.org/10.1071/wf18126.
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Given the recent history of frequent and extensive late dry season wildfire in Australia’s fire-prone northern savannas, regional conservation-based fire management programs typically aim to mitigate wildfire through the use of strategic prescribed burning during the cooler early dry season. However, it remains unclear as to the extent such environmental management concerns are being addressed by these renewed fire management efforts. This study documents changes in fire regime in the western Arnhem Land region of northern Australia associated with the implementation of active fire management since 2006. Over a 12-year period, the regional fire regime has transitioned from late dry season, wildfire-dominated to being characterised by a majority of fires occurring as small early dry season prescribed burns. Although overall area burnt has not significantly decreased, most ecological threshold metrics have improved, with the exception of those describing the maintenance of longer-unburnt habitat. Challenges involved with defining, delivering, monitoring and evaluating heterogeneity targets are discussed.
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Tollefson, Jeff. „Dry Amazon could see record fire season“. Nature 535, Nr. 7610 (29.06.2016): 18–19. http://dx.doi.org/10.1038/nature.2016.20190.
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Campbell, Ken. „Dry Hydrants Supply Year-Round Fire Protection“. Opflow 20, Nr. 11 (November 1994): 3. http://dx.doi.org/10.1002/j.1551-8701.1994.tb00972.x.
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Rorig, Miriam L., Steven J. McKay, Sue A. Ferguson und Paul Werth. „Model-Generated Predictions of Dry Thunderstorm Potential“. Journal of Applied Meteorology and Climatology 46, Nr. 5 (01.05.2007): 605–14. http://dx.doi.org/10.1175/jam2482.1.
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Abstract Dry thunderstorms (those that occur without significant rainfall at the ground) are common in the interior western United States. Moisture drawn into the area from the Gulfs of Mexico and California is sufficient to form high-based thunderstorms. Rain often evaporates before reaching the ground, and cloud-to-ground lightning generated by these storms strikes dry fuels. Fire weather forecasters at the National Weather Service and the National Interagency Coordination Center try to anticipate days with widespread dry thunderstorms because they result in multiple fire ignitions, often in remote areas. The probability of the occurrence of dry thunderstorms that produce fire-igniting lightning strikes was found to be greater on days with high instability and a deficit of moisture at low levels of the atmosphere. Based on these upper-air variables, an algorithm was developed to estimate the potential of dry lightning (lightning that strikes the ground with little or no rainfall at the surface) when convective storms are expected. In the current study, this algorithm has been applied throughout the western United States, with modeled meteorological variables rather than the observed soundings that have previously been used, to develop a predictive scheme for estimating the risk of dry thunderstorms. Predictions of the risk of dry thunderstorms were generated from real-time forecasts using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) for the summers of 2004 and 2005. During that period, 240 large lightning-caused fires were ignited in the model domain. Of those fires, 40% occurred where the probability of dry lightning was predicted to be equal to or greater than 90% and 58% occurred where the probability was 75% or greater.
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Weier, Anna, Ian J. Radford, Sofia L. J. Oliveira und Michael J. Lawes. „Recently but infrequently burnt breeding sites are favoured by threatened Gouldian finches (Erythrura gouldiae)“. International Journal of Wildland Fire 25, Nr. 12 (2016): 1281. http://dx.doi.org/10.1071/wf16105.
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Frequent and extensive fires are becoming increasingly common throughout the tropical savannas of northern Australia. This fire regime has been implicated in both habitat alteration and losses of biodiversity. Granivorous birds are particularly affected because of the effect of fire on grass seed availability. The endemic Gouldian finch (Erythrura gouldiae) has experienced population declines in recent decades, potentially in response to changed fire regimes. Using breeding data from monitored artificial nest-boxes, this study examined the choice of breeding site by Gouldian finches in response to several attributes of the prevailing fire regime. The fire regime was characterised using remote sensing analysis of annual fire scars. Time since last fire and fire frequency were the most useful predictors of breeding site occupancy. Gouldian finches favoured recently burnt sites (previous dry season), but also sites that were infrequently burnt (return time of 2–3 years). Consequently, under the current regime of many frequent fires, Gouldian finches move among breeding sites and display low seasonal site fidelity. Our findings provide support for the notion that the Gouldian finch favours a fine-grain patch-mosaic fire regime and that contemporary large-scale fire regimes are likely contributing to their decline.
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Nielsen, Thomas Theis, und Kjeld Rasmussen. „Utilization of NOAA AVHRR for assessing the determinants of savanna fire distribution in Burkina Faso“. International Journal of Wildland Fire 10, Nr. 2 (2001): 129. http://dx.doi.org/10.1071/wf01015.
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Temporal and spatial patterns of active fires, detected using NOAA AVHRR LAC data, in Burkina Faso are identified and related to vegetation, tree cover and land use classes. Initially, fires are classified into early and late dry season fires (EDSF and LDSF). Early dry season fires are defined as fires occurring earlier than 45 days after the start of the dry season, marked by a levelling out in the post-rainy season temperature increase, determined on the basis of surface temperature data derived from NOAA AVHRR. The date of the start of the dry season, defined in this way, is shown to be a linear function of the latitude. The distribution of fire occurrence are shown to display distinctively different patterns. These distribution patterns are related to information on vegetation class, woody biomass and land use intensity as well as net primary productivity, estimated from NOAA AVHRR rainy season data. It is shown that overall fire frequency and the ratio of early to late dry season fire activity depend strongly on net primary productivity, land use intensity and vegetation class. Late fires tend to occur mainly in agricultural areas, whereas early fires are much more frequent in areas of low land use intensity in the wooded savannas of southern Burkina Faso.
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Burrows, N. D. „Flame residence times and rates of weight loss of eucalypt forest fuel particles“. International Journal of Wildland Fire 10, Nr. 2 (2001): 137. http://dx.doi.org/10.1071/wf01005.
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Shape, size, composition and arrangement of fuel particles within a fuel array significantly affect the way in which wildland fires behave. Australian eucalypt forest fire behaviour models characterise fine fuels according to the quantity burnt in the flaming zone, and the upper size limit for fine fuel particles is somewhat arbitrarily set at 6 mm for the McArthur Forest Fire Danger Meter and 10 mm for the Forest Fire Behaviour Tables for Western Australia. Flame residence time and rate of weight loss during combustion of dry eucalypt leaves and different dimensions of round wood were measured to provide a scientific basis for standardising litter fuel sampling in dry eucalypt forests. Eucalypt leaves burnt at a rate equivalent to a piece of 4 mm diameter round wood, with smaller diameter round wood being the most flammable component of the fuel array. Based on flame residence times of individual fuel particles measured in the laboratory, and eucalypt surface fuel arrays observed in the field, fine litter fuel sampling should be standardised to leaves and round wood less than 6 mm in diameter. This study also enables the determination of the contribution of larger fuel particles to flaming zone combustion and intensity.
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Werner, Patricia A., und Donald C. Franklin. „Resprouting and mortality of juvenile eucalypts in an Australian savanna: impacts of fire season and annual sorghum“. Australian Journal of Botany 58, Nr. 8 (2010): 619. http://dx.doi.org/10.1071/bt10139.
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In northern Australian savannas, canopy tree species often have juvenile tree banks that are composed mainly of small individuals of indeterminate age that have resprouted repeatedly after fire. Little is known about their demography. We report the initial responses (mortality, topkill and resprouting type) of 3133 marked juvenile eucalypts to set fires of different seasons (early dry season, late dry season, wet season, unburnt) in a 32 400 m2 field experiment. Fire treatments were repeated in plots dominated by a native annual grass (sorghum) that becomes senescent before the early dry season and provides the main fuel of savanna fires, and in others with little or no sorghum, but instead other native grasses and forbs that remain green well into the dry season. Most juvenile eucalypts <150 cm high were topkilled but resprouted from underground tissues regardless of fire season or understorey (86–100% vs <5% in unburnt plots). Few saplings 200–500 cm high died or were topkilled, but impacts of fire were harsher in sorghum than in non-sorghum vegetation. The response of eucalypts 150–199 cm high was intermediate, suggesting a ‘tactical’ transition from suppressed persistence to growth toward maturity. Counter-intuitively, genet death of juvenile trees was >22% in the low-intensity early dry season fire in plots with little or no annual sorghum, compared with <2% in all other fire/understorey combinations. We suggest results are related to fire behaviour, seasonal carbohydrate storage dynamics and competition with ground-layer plants.
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Yokelson, R. J., I. R. Burling, S. P. Urbanski, E. L. Atlas, K. Adachi, P. R. Buseck, C. Wiedinmyer, S. K. Akagi, D. W. Toohey und C. E. Wold. „Trace gas and particle emissions from open biomass burning in Mexico“. Atmospheric Chemistry and Physics Discussions 11, Nr. 3 (03.03.2011): 7321–74. http://dx.doi.org/10.5194/acpd-11-7321-2011.
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Abstract. We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NOx, NH3, H2, and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx EF. When considering all fires sampled, the percentage of particles containing soot increased from 15 to 60% as the modified combustion efficiency increased from 0.88 to 0.98. We estimate that about 175 Tg of fuel was consumed by open burning of biomass and garbage and as biofuel (mainly wood cooking fires) in Mexico in 2006. Combining the fuel consumption estimates with our EF measurements suggests that the above combustion sources account for a large fraction of the reactive trace gases and more than 90% of the total primary, fine carbonaceous particles emitted by all combustion sources in Mexico.
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Yokelson, R. J., I. R. Burling, S. P. Urbanski, E. L. Atlas, K. Adachi, P. R. Buseck, C. Wiedinmyer, S. K. Akagi, D. W. Toohey und C. E. Wold. „Trace gas and particle emissions from open biomass burning in Mexico“. Atmospheric Chemistry and Physics 11, Nr. 14 (18.07.2011): 6787–808. http://dx.doi.org/10.5194/acp-11-6787-2011.
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Abstract. We report airborne measurements of emission factors (EF) for trace gases and PM2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF measured late in the African dry season they were at least 1.7 times larger for NOx, NH3, H2, and most non-methane organic compounds. Our measurements suggest that urban deposition and high windspeed may also be associated with significantly elevated NOx EF. When considering all fires sampled, the percentage of particles containing soot increased from 15 to 60 % as the modified combustion efficiency increased from 0.88 to 0.98. We estimate that about 175 Tg of fuel was consumed by open burning of biomass and garbage and as biofuel (mainly wood cooking fires) in Mexico in 2006. Combining the fuel consumption estimates with our EF measurements suggests that the above combustion sources account for a large fraction of the reactive trace gases and more than 90 % of the total primary, fine carbonaceous particles emitted by all combustion sources in Mexico.
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Nicholson, Evelyn, Alan Lill und Alan Andersen. „Do tropical savanna skink assemblages show a short-term response to low-intensity fire?“ Wildlife Research 33, Nr. 4 (2006): 331. http://dx.doi.org/10.1071/wr05067.
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The composition of skink assemblages at a tropical savanna site in northern Australia was documented immediately before and after low-intensity, experimental fires in the early dry season (June), and compared with the composition in neighbouring unburnt plots. The composition of the assemblage of captured skinks was not significantly affected by fire, and no change in total abundance of skinks was recorded. Arthropods constitute the principal food of the skinks and the composition of the captured arthropod samples on the treatment plots was significantly affected by the fires, with spiders, beetles and hemipterans increasing in numbers during the immediate post-fire period. Seasonal changes in captured skink assemblage composition, unrelated to the fire event, occurred between the wet–dry season transition and the early dry season. These changes were associated with variation in four weather variables and were possibly also related to seasonal reproductive activity. Our study demonstrates a high degree of resilience of savanna skinks to individual fire events; however, the longer-term effect of different fire regimes requires further investigation.
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Brockett, B. H., H. C. Biggs und B. W. van Wilgen. „A patch mosaic burning system for conservation areas in southern African savannas“. International Journal of Wildland Fire 10, Nr. 2 (2001): 169. http://dx.doi.org/10.1071/wf01024.
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Fire-prone savanna ecosystems in southern African conservation areas are managed by prescribed burning in order to conserve biodiversity. A prescribed burning system designed to maximise the benefits of a diverse fire regime in savanna conservation areas is described. The area burnt per year is a function of the grass fuel load, and the number of fires per year is a function of the percentage area burnt. Fires are point-ignited, under a range of fuel and weather conditions, and allowed to burn out by themselves. The seasonal distribution of planned fires over a year is dependent on the number of fires. Early dry season fires (May–June) tend to be small because fuels have not yet fully cured, while late season fires (August–November) are larger. More fires are ignited in the early dry season, with fewer in the late dry season. The seasonality, area burnt, and fire intensity are spatially and temporally varied across a landscape. This should result in the creation of mosaics, which should vary in extent and existence in time. Envelopes for the accumulated percentage to be burnt per month, over the specified fire season, together with upper and lower buffers to the target area are proposed. The system was formalised after 8 years of development and testing in Pilanesberg National Park, South Africa. The spatial heterogeneity of fire patterns increased over the latter years of implementation. This fire management system is recommended for savanna conservation areas of >20 000 ha in size.
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Woinarski, JCZ, C. Brock, A. Fisher, D. Milne und B. Oliver. „Response of Birds and Reptiles to Fire Regimes on Pastoral Land in the Victoria River District, Northern Territory.“ Rangeland Journal 21, Nr. 1 (1999): 24. http://dx.doi.org/10.1071/rj9990024.
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Birds and reptiles were censused at two sites of contrasting soil texture (clay, loam) on pastoral land in the Victoria River District, Northern Territory. Both sites comprised 16 plots (each of 2.6 ha) subjected to seven different experimental fire regimes (unburnt, burnt in the early dry season at 2, 4 and 6 year intervals, and burnt in the late dry season at 2, 4 and 6 year intervals) beginning five years before sampling (and thus, not all regimes had been operationally distinct between the onset of the experiment and this sampling). The regimes were deconstructed to four fire factors: the imposed regime, the time since last fire, the number of fires since the inception of the experiment, and the number of hot (=late dry season) fires. Of 30 species recorded from at least four plots, 12 were significantly associated with time since last fire. These responses were mostly to the extremes - some species were associated with the most recently burnt areas, and others occurred mainly in the plots which had been unburnt the longest. Longer- term responses to fire regimes were generally less clearcut, possibly because the relatively short duration of the imposed experimental fire treatments had not yet brought about substantial environmental divergence. Key words: fire regime, tropical savannas, birds, reptiles, diversity.
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Williams, RJ, AM Gill und PHR Moore. „Seasonal Changes in Fire Behaviour in a Tropical Savanna in Northern Australia“. International Journal of Wildland Fire 8, Nr. 4 (1998): 227. http://dx.doi.org/10.1071/wf9980227.
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In a landscape-scale experiment, fires were lit in replicate catchments 15-20 km2 in area, either early in the dry season (June) or late in the dry season (September) between 1990 and 1994. For each fire, Byram-intensity was determined in representative one ha areas of Eucalyptus miniata – E. tetrodonta open-forest, with a ground stratum dominated by annual grasses. Fuel weights were measured by harvest, fuel heat content was assumed to be constant, and the rate of spread was determined using electronic timers. Fuels consisted primarily of grass and leaf litter, and ranged from 1.5 to 13 t ha-1; in most years, average fuel loads were 2-4 t ha-1. Rates of spread were generally in the range of 0.2-0.8 ms-1. The mean intensity of early dry season fires (2100 kW m-1) was significantly less than that of the late dry season fires (7700 kW m-1), primarily because, in the late dry season, there was more leaf litter, fuels were drier, and fire weather was more extreme. Crown fires, a feature of forest fires of high intensity in southeastern Australia, were not observed in the Kapalga fires. Fire intensity was a very good predictor of both leaf-char height and leaf-scorch height for fires between 100 kW m-1 and 10,000 kW m-1, the range in which the majority of experimental fires fell.
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Ansley, RJ, DL Jones, TR Tunnell, BA Kramp und PW Jacoby. „Honey Mesquite Canopy Responses to Single Winter Fires: Relation to Herbaceous Fuel, Weather and Fire Temperature“. International Journal of Wildland Fire 8, Nr. 4 (1998): 241. http://dx.doi.org/10.1071/wf9980241.
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Honey mesquite (Prosopis glandulosa Torr.) canopy responses to fire were measured following 20 single winter fires conducted in north Texas. Weather conditions during the fires, understory herbaceous fine fuel (fine fuel) amount and moisture content, fire temperature at 0 cm, 10-30 cm and 1-3 m above ground, and canopy responses were compared. Ten fires occurred on a site where fine fuel was a mixture of cool and warm season grasses (mixed site). The other 10 fires occurred on a site dominated by warm season grasses (warm site). When both sites were included in regressions, peak fire temperature at all heights was positively related to fine fuel amount. Fine fuel amount, fine fuel moisture content, air temperature (AT) and relative humidity (RH) affected fire temperature duration in seconds over 100°C (FTD100) at 1-3 m height, but not at ground level. Mesquite percent above-ground mortality (topkill) increased with increasing fine fuel amount, decreasing fuel moisture content, increasing AT, and decreasing RH. Percent foliage remaining on non-topkilled (NTK) trees was inversely related to fine fuel amount and AT, and positively related to fine fuel moisture content. Effect of fire on mesquite topkill and foliage remaining of NTK trees was strongly affected by RH at the warm site (r2 = 0.92 and 0.82, respectively), but not at the mixed site. This difference was due to RH affecting fuel moisture content (and subsequently fire behavior) to a greater degree at the warm than at the mixed site, because of the lower green tissue content in warm site grasses at the time of burning. Under adequate fine fuel amounts to carry a fire, mesquite canopy responses to fire (i.e., topkill vs, partial canopy defoliation) were largely determined by AT and RH conditions during the fire. This has implications if the management goal is to preserve the mesquite overstory for a savanna result instead of topkilling all trees. Two substudies were conducted during 3 of the fires. Substudy 1 determined mesquite response to fire in 2 plots with different understory herbaceous fuel loads (5,759 vs. 2,547 kg/ha) that were burned under under similar weather conditions. Mesquite topkill was 81% and 11% in the high and low fuel fires, respectively. Under similar weather conditions, fine fuel was an important factor in affecting mesquite responses to fire. However, as demonstrated in the main study, under a variety of weather conditions, AT and RH influenced mesquite response to fire as much or more than did fine fuel. Substudy 2 compared response of mesquite plants with abundant and dry subcanopy fine fuel (3252 kg/ha; fuel moisture 10.4%), or sparse and green subcanopy fuel (1155 kg/ha; fuel moisture 25.9%) to a high intensity fire. All trees were topkilled, including those with low subcanopy fuel, probably from convection heat generated from herbaceous fuel in interspaces between trees. In support of this conclusion, thermocouple data from all 20 fires indicated that canopy responses were more related to fire temperature at 1-3 m than at lower heights. This suggests that the topkill mechanism was due to convective heat within the canopy rather than a girdling effect of fire at stem bases.
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Leng, Ning Bo, Shun Xi Wang und Pei Han. „Development of New Fire Extinguishing Agent for Grassland“. Advanced Materials Research 550-553 (Juli 2012): 62–70. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.62.
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Selecting ammonium dihydrogen phosphate of ultra-fine processing and surface modification as the main agent of fire extinguishing agent, mica powder, activated clay, talc, calcium carbonate as an inert filler, ND1 as additive, developed specifically for the grassland fire characteristics of ultra-fine dry powder fire extinguishing agent grassland; tested the moisture absorption rate, water repellency, bulk density and fluidity and other technical indicators; using quadrat grassed ignition method on new grassland fire extinguishing agent research the fire extinguishing efficiency and cost.
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Melo, Pedro, Javier Sparacino, Daihana Argibay, Vicente Sousa Júnior, Roseli Barros und Giovana Espindola. „Assessing Wildfire Regimes in Indigenous Lands of the Brazilian Savannah-Like Cerrado“. Fire 4, Nr. 3 (05.07.2021): 34. http://dx.doi.org/10.3390/fire4030034.
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The Brazilian savannah-like Cerrado is classified as a fire-dependent biome. Human activities have altered the fire regimes in the region, and as a result, not all fires have ecological benefits. The indigenous lands (ILs) of the Brazilian Cerrado have registered the recurrence of forest fires. Thus, the diagnosis of these events is fundamental to understanding the burning regimes and their consequences. The main objective of this paper is to evaluate the fire regimes in Cerrado’s indigenous lands from 2008 to 2017. We used the Landsat time series, at 30 m spatial resolution, available in the Google Earth Engine platform to delineate the burned areas. We used precipitation data from a meteorological station to define the rainy season (RS), early dry season (EDS), middle dry season (MDS), and late dry season (LDS) periods. During 2008–2017, our results show that the total burned area in the indigenous lands and surrounding area was 2,289,562 hectares, distributed in 14,653 scars. Most fires took place between June and November, and the annual burned area was quite different in the years studied. It was also possible to identify areas with high fire recurrence. The fire regime patterns described here are the first step towards understanding the fire regimes in the region and establishing directions to improve management strategies and guide public policies.