scholarly journals New In-Flame Flammability Testing Method Applied to Monitor Seasonal Changes in Live Fuel

Fire ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 1
Author(s):  
Oleg M. Melnik ◽  
Stephen A. Paskaluk ◽  
Mark Y. Ackerman ◽  
Katharine O. Melnik ◽  
Dan K. Thompson ◽  
...  
Keyword(s):  
Flame Front ◽  
Energy Release ◽  
Energy Content ◽  
Oxygen Deficiency ◽  
Fire Behavior ◽  
Crown Fire ◽  
Dominant Component ◽  
Oxygen Consumption Calorimetry ◽  
Methane Flame ◽  
Fire Flame

Improving the accuracy of fire behavior prediction requires better understanding of live fuel, the dominant component of tree crowns, which dictates the consumption and energy release of the crown fire flame-front. Live fuel flammability is not well represented by existing evaluation methods. High-flammability live fuel, e.g., in conifers, may maintain or increase the energy release of the advancing crown fire flame-front, while low-flammability live fuel, e.g., in boreal deciduous stands, may reduce or eventually suppress flame-front energy release. To better characterize these fuel–flame-front interactions, we propose a method for quantifying flammability as the fuel’s net effect on (contribution to) the frontal flame energy release, in which the frontal flame is simulated using a methane diffusion flame. The fuel’s energy release contribution to the methane flame was measured using oxygen consumption calorimetry as the difference in energy release between the methane flame interacting with live fuel and the methane flame alone. In-flame testing resulted in fuel ignition and consumption comparable to those in wildfires. The energy release contribution of live fuel was significantly lower than its energy content measured using standard methods, suggesting better sensitivity of the proposed metric to water content- and oxygen deficiency-associated energy release reductions within the combustion zone.

scholarly journals Needle Senescence Affects Fire Behavior in Aleppo Pine (Pinus halepensis Mill.) Stands: A Simulation Study

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1054 ◽  
Author(s):  
Rodrigo Balaguer-Romano ◽  
Rubén Díaz-Sierra ◽  
Javier Madrigal ◽  
Jordi Voltas ◽  
Víctor Resco de Dios
Keyword(s):  
Mediterranean Basin ◽  
Fire Behavior ◽  
Western Mediterranean ◽  
Aleppo Pine ◽  
Fire Season ◽  
Burned Area ◽  
Crown Fire ◽  
Wind Speeds ◽  
Western Mediterranean Basin ◽  
Needle Senescence

Research Highlights: Pre-programmed cell death in old Aleppo pine needles leads to low moisture contents in the forest canopy in July, the time when fire activity nears its peak in the Western Mediterranean Basin. Here, we show, for the first time, that such needle senescence may increase fire behavior and thus is a potential mechanism explaining why the bulk of the annual burned area in the region occurs in early summer. Background and Objectives: The brunt of the fire season in the Western Mediterranean Basin occurs at the beginning of July, when live fuel moisture content is near its maximum. Here, we test whether a potential explanation to this conundrum lies in Aleppo pine needle senescence, a result of pre-programmed cell death in 3-years-old needles, which typically occurs in the weeks preceding the peak in the burned area. Our objective was to simulate the effects of needle senescence on fire behavior. Materials and Methods: We simulated the effects of needle senescence on canopy moisture and structure. Fire behavior was simulated across different phenological scenarios and for two highly contrasting Aleppo pine stand structures, a forest, and a shrubland. Wildfire behavior simulations were done with BehavePlus6 across a wide range of wind speeds and of dead fine surface fuel moistures. Results: The transition from surface to passive crown fire occurred at lower wind speeds under simulated needle senescence in the forest and in the shrubland. Transitions to active crown fire only occurred in the shrubland under needle senescence. Maximum fire intensity and severity were always recorded in the needle senescence scenario. Conclusions: Aleppo pine needle senescence may enhance the probability of crown fire development at the onset of the fire season, and it could partly explain the concentration of fire activity in early July in the Western Mediterranean Basin.

Characterizing Canopy Fuels to Predict Fire Behavior in Pitch Pine Stands

2007 ◽  
Vol 24 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Matthew J. Duveneck ◽  
William A. Patterson
Keyword(s):  
Fire Behavior ◽  
Small Diameter ◽  
Basal Area ◽  
Regression Equations ◽  
Crown Fire ◽  
Pinus Rigida ◽  
Canopy Fuels ◽  
Pitch Pine ◽  
Thinning Operations ◽  
Pine Stands

Abstract Destructive sampling of 31 pitch pine (Pinus rigida P. Mill) trees ranging in dbh from 2.7 to 42.5 cm and in height from 4.1 to 23.8 m provided a complete inventory of needles and small-diameter branch weights used to characterize canopy fuels to predict fire behavior in pitch pine stands. Regression equations using dbh as an independent variable predict canopy bulk density with an r2 > 0.93. The results provide managers with a method of evaluating the effectiveness of thinning operations in reducing crown fire potential in well-stocked stands. To demonstrate the application of the method, we calculated the wind speed (Crowning Index [CI]) needed to sustain an active crown fire in thinned and unthinned pitch pine stands in Montague, Massachusetts. Thinning to 2.8 m2/ha basal area increased the CI from 34 to 98 km/hour.

scholarly journals Evaluating Potential Fire Behavior in Lodgepole Pine-Dominated Forests after a Mountain Pine Beetle Epidemic in North-Central Colorado

2011 ◽  
Vol 26 (3) ◽  
pp. 101-109 ◽  
Author(s):  
Jennifer G. Klutsch ◽  
Mike A. Battaglia ◽  
Daniel R. West ◽  
Sheryl L. Costello ◽  
José F. Negrón
Keyword(s):  
Mountain Pine Beetle ◽  
Tree Mortality ◽  
Lodgepole Pine ◽  
Fire Behavior ◽  
Crown Fire ◽  
Tree Species Composition ◽  
Surface Fire ◽  
Mountain Pine ◽  
Pine Beetle ◽  
Fuel Characteristics

Abstract A mountain pine beetle outbreak in Colorado lodgepole pine forests has altered stand and fuel characteristics that affect potential fire behavior. Using the Fire and Fuels Extension to the Forest Vegetation Simulator, potential fire behavior was modeled for uninfested and mountain pine beetle-affected plots 7 years after outbreak initiation and 10 and 80% projected tree fall using measured and projected fuel and stand characteristics. Under 90th percentile weather conditions, uninfested plots exhibited proportionally more crown fire than infested plots. Plots predicted to have crown fire were composed mainly of nonhost conifer species and had a lower and more continuous canopy than infested plots. Where surface fire was predicted to occur, live lodgepole pine was the only conifer present, and plots had significantly lower tree mortality from fire than plots predicted to have crown fire. Mountain pine beetle-induced changes in stand and fuel characteristics resulted in increased intensity of surface fire behavior. Furthermore, with 80% infested tree fall, potential smoke production was predicted to be higher. Tree species composition of stands pre and postbark beetle outbreak is important when identifying mountain pine beetle-caused changes to potential fire behavior.

Simulating fuel treatment effects in dry forests of the western United States: testing the principles of a fire-safe forest

2011 ◽  
Vol 41 (5) ◽  
pp. 1018-1030 ◽  
Author(s):  
Morris C. Johnson ◽  
Maureen C. Kennedy ◽  
David L. Peterson
Keyword(s):  
United States ◽  
Treatment Effects ◽  
Fire Hazard ◽  
Fire Behavior ◽  
Post Treatment ◽  
Western United States ◽  
Crown Fire ◽  
Fuel Treatments ◽  
Dry Forests ◽  
Fuel Treatment

We used the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) to simulate fuel treatment effects on 45 162 stands in low- to midelevation dry forests (e.g., ponderosa pine ( Pinus ponderosa Dougl. ex. P. & C. Laws.) and Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) of the western United States. We evaluated treatment effects on predicted post-treatment fire behavior (fire type) and fire hazard (torching index). FFE-FVS predicts that thinning and surface fuel treatments reduced crown fire behavior relative to no treatment; a large proportion of stands were predicted to transition from active crown fire pre-treatment to surface fire post-treatment. Intense thinning treatments (125 and 250 residual trees·ha–1) were predicted to be more effective than light thinning treatments (500 and 750 residual trees·ha–1). Prescribed fire was predicted to be the most effective surface fuel treatment, whereas FFE-FVS predicted no difference between no surface fuel treatment and extraction of fuels. This inability to discriminate the effects of certain fuel treatments illuminates the consequence of a documented limitation in how FFE-FVS incorporates fuel models and we suggest improvements. The concurrence of results from modeling and empirical studies provides quantitative support for “fire-safe” principles of forest fuel reduction (sensu Agee and Skinner 2005. For. Ecol. Manag. 211: 83–96).

Prediction of crown fire behavior in two stands of jack pine

1993 ◽  
Vol 23 (3) ◽  
pp. 442-449 ◽  
Author(s):  
C.E. Van Wagner
Keyword(s):  
Physical Theory ◽  
Fire Behavior ◽  
Jack Pine ◽  
Published Data ◽  
Critical Surface ◽  
Crown Fire ◽  
Spread Rate ◽  
Empirical Observation ◽  
Surface Fires ◽  
Independent Variable

Published data on two sets of experimental fires in jack pine (Pinusbanksiana Lamb.) forest were subjected to two forms of analysis. The first was a classification into surface fires and two kinds of crown fire, passive and active. In the second, the data were used to develop a model to predict both the spread rate of fire and the degree of crown consumption. The model consists mainly of two limiting equations for spread rate, one for surface fires and the other for full crowning fires; the independent variable is the Canadian Initial Spread Index. A critical surface intensity is first used to distinguish surface fires from crowning fires. A further process then estimates the degree of crowning and places the calculated final spread rate somewhere in the space between the limiting equations. The model inputs include six physical stand properties plus a pre-estimate of surface fuel consumption. It is a blend of physical theory and empirical observation.

scholarly journals Yield of green fodder of annual mixtures with participation of sudanese grass in conditions of Polisya

1970 ◽  
pp. 161-171
Author(s):  
O.V. Vishnevska ◽  
O.V. Markina
Keyword(s):  
Energy Content ◽  
Growth Yield ◽  
Dry Weight ◽  
Component Composition ◽  
Metabolic Energy ◽  
Dominant Component ◽  
Green Fodder ◽  
Digestible Protein ◽  
Fertilization System ◽  
Feed Unit

Purpose. To study the features of the formation, growth, yield and nutritional value of mixtures involving Sudanese grass in the production of green fodder with different component composition and fertilization system. Methods. Field, laboratory, mathematical. Results. According to the results of the studies, it was found that the dominant component of cenoses, the Sudanese grass, forms the height of plants at the level of 87-151 cm, the components of the mixtures – 48,4-95,9 cm. The fertilization system contributed to the linear development of cenosis plants by 9-39% in Sudanese grass and 6-62% in the components of mixtures, compared with the control options. The results of the studies of the cenosis productivity with participation of Sudanese grass, which on the sod-podzolic soils of Polisya amounted to 16,2-44,8 t/ha of greenery, or 3,3-9,1 t/ha of dry weight, the efficiency of the fertilization system was up to 38%. The yield of nutrients was 2.54-7.64 t/ha of feed units and 0.47-1.41 t/ha of digestible protein, the fertilizer system increased the yield of nutrients by 6-72%. The feed unit is provided with digestible protein at the level of 168.7-200.6 g. It was found that the content of exchangeable energy in 1 kg of feed obtained from mixtures is 9.6-10.4 mJ. According to the competitiveness coefficient (K = 1.47-2.74), the optimal fertilization system for these cenoses was selected – N16Р16К16. Conclusions. In terms of productivity (16.2-44.8 t/ha of green, or 3.3-9.1 t/ha of dry, weight) and nutrition (168.7-200.6 g feed unit digestible protein availability, metabolic energy content – 9,6-10,4 mJ per 1 kg of feed), multicomponent cenoses with the participation of Sudanese grass for the production of green feed in the Polisya zone have been developed.

scholarly journals Overstory Longleaf Pines and Hardwoods Create Diverse Patterns of Energy Release and Fire Effects During Prescribed Fire

2021 ◽  
Vol 4 ◽  
Author(s):  
Andrew W. Whelan ◽  
Seth W. Bigelow ◽  
Joseph J. O’Brien
Keyword(s):  
Energy Release ◽  
Longleaf Pine ◽  
Fire Behavior ◽  
Fire Effects ◽  
Additive Models ◽  
Ground Layer ◽  
Neighborhood Models ◽  
Pine Regeneration ◽  
Dormant Season ◽  
Overstory Trees

Litter from pine trees in open woodlands is an important fuel for surface fires, but litter from hardwood species may quell fire behavior. Lower intensity fires favor hardwood over longleaf pine regeneration, and while overstory hardwoods are important sources of food and shelter for many wildlife species, too many could result in canopy closure and a loss of ground layer diversity. Although some researchers have found synergies in fire effects when leaves of different species are combined, field tests of effects of tree guild diversity on fire behavior are lacking from the literature. We used neighborhood modeling to understand how diverse overstory trees in longleaf pine forests affect fire radiative energy density (FRED), and to determine the effect on top-kill of shrub-form hardwood trees. We measured the effects of three guilds of overstory trees (longleaf pine, upland oaks, and mesic oaks) on FRED, and related FRED to post-fire damage in four guilds of understory hardwoods (sandhill oaks, upland oaks, mesic oaks, and fleshy-fruited hardwoods). We found that FRED increased 33–56% near overstory longleaf pine but decreased 23–37% near overstory mesic oaks. Additive models of FRED performed well and no synergies or antagonisms were present. Seventy percent of stems of understory hardwoods survived fire with energy release typical of dormant-season fires in canopy gaps and near overstory mesic oaks. We also found that among understory trees >2 m tall, upland and sandhill oaks were more likely than mesic oaks or fleshy-fruited hardwoods to avoid top-kill. We conclude that neighborhood models provide a method to predict longleaf pine forest structure and composition that allows for the ecological benefits of overstory hardwoods while maintaining ground-layer diversity. To maintain hardwood control, fire practitioners may need to select fire weather conditions to increase fire behavior especially during dormant-season burns.

scholarly journals Firefighter Observations of “Surprising” Fire Behavior in Mountain Pine Beetle-Attacked Lodgepole Pine Forests

Fire ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 34 ◽  
Author(s):  
Kevin Moriarty ◽  
Antony S. Cheng ◽  
Chad M. Hoffman ◽  
Stuart P. Cottrell ◽  
Martin E. Alexander
Keyword(s):  
Mountain Pine Beetle ◽  
Lodgepole Pine ◽  
Fire Behavior ◽  
Pine Forests ◽  
Fuel Moisture ◽  
Crown Fire ◽  
Gray Phase ◽  
Mountain Pine ◽  
Pine Beetle ◽  
Moisture Conditions

The recent mountain pine beetle outbreak affecting lodgepole pine forests in the Rocky Mountains has created a novel fire environment for wildland firefighters. This paper presents results from an examination of firefighters’ observations of fire behavior in post-outbreak lodgepole pine forests, with a focus on what they considered surprising from a fire behavior standpoint and how this in turn affected their suppression tactics. The surprises in fire behavior experienced by firefighters during the red phase of post-outbreak forests included an elevated level of fire spread and intensity under moderate weather and fuel moisture conditions, increased spotting, and faster surface-to-crown fire transitions with limited or no ladder fuels. Unexpectedly, during the gray phase in mountain pine beetle-attacked stands, crown ignition and crown fire propagation was observed for short periods of time. Firefighters are now more likely to expect to see active fire behavior in nearly all fire weather and fuel moisture conditions, not just under critically dry and windy situations, and across all mountain pine beetle attack phases, not just the red phase. Firefighters changed their suppression tactics by adopting indirect methods due to the potential fire behavior and tree-fall hazards associated with mountain pine beetle-attacked lodgepole pine forests.

scholarly journals Surface Fire Intensity Influences Simulated Crown Fire Behavior in Lodgepole Pine Forests with Recent Mountain Pine Beetle-Caused Tree Mortality

2013 ◽  
Vol 59 (4) ◽  
pp. 390-399 ◽  
Author(s):  
Chad M. Hoffman ◽  
Penelope Morgan ◽  
William Mell ◽  
Russell Parsons ◽  
Eva Strand ◽  
...  
Keyword(s):  
Mountain Pine Beetle ◽  
Tree Mortality ◽  
Lodgepole Pine ◽  
Fire Behavior ◽  
Pine Forests ◽  
Fire Intensity ◽  
Crown Fire ◽  
Surface Fire ◽  
Mountain Pine ◽  
Pine Beetle

scholarly journals Magnetic reconnection and energy release on the Sun and solar-like stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 191-200
Author(s):  
Lidia van Driel-Gesztelyi
Keyword(s):  
Free Energy ◽  
Magnetic Reconnection ◽  
Energy Release ◽  
Energy Content ◽  
Magnetic Flux Density ◽  
The Sun ◽  
X Rays ◽  
Stellar Flares ◽  
Wide Wavelength Range ◽  
Hot Corona

AbstractMagnetic reconnection is thought to play an important role in liberating free energy stored in stressed magnetic fields. The consequences vary from undetectable nanoflares to huge flares, which have signatures over a wide wavelength range, depending on e.g. magnetic topology, free energy content, total flux, and magnetic flux density of the structures involved. Events of small energy release, which are thought to be the most numerous, are one of the key factors in the existence of a hot corona in the Sun and solar-like stars. The majority of large flares are ejective, i.e. involve the expulsion of large quantities of mass and magnetic field from the star. Since magnetic reconnection requires small length-scales, which are well below the spatial resolution limits of even the solar observations, we cannot directly observe magnetic reconnection happening. However, there is a plethora of indirect evidences from X-rays to radio observations of magnetic reconnection. I discuss key observational signatures of flares on the Sun and solar-paradigm stellar flares and describe models emphasizing synergy between observations and theory.

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