How to generate and interpret fire characteristics charts for the U.S. fire danger rating system

Treesearch

Faith Ann Heinsch; Patricia L. Andrews; Deb Tirmenstein

2017-01-01

The fire characteristics chart is a graphical method of presenting U.S. National Fire Danger Rating System (NFDRS) indexes and components as well as primary surface or crown fire behavior characteristics. Computer software has been developed to produce fire characteristics charts for both fire danger and fire behavior in a format suitable for inclusion in reports and...

Numerical modeling of laboratory-scale surface-to-crown fire transition

NASA Astrophysics Data System (ADS)

Castle, Drew Clayton

Understanding the conditions leading to the transition of fire spread from a surface fuel to an elevated (crown) fuel is critical to effective fire risk assessment and management. Surface fires that successfully transition to crown fires can be very difficult to suppress, potentially leading to damages in the natural and built environments. This is relevant to chaparral shrub lands which are common throughout parts of the Southwest U.S. and represent a significant part of the wildland urban interface. The ability of the Wildland-Urban Interface Fire Dynamic Simulator (WFDS) to model surface-to-crown fire transition was evaluated through comparison to laboratory experiments. The WFDS model is being developed by the U.S. Forest Service (USFS) and the National Institute of Standards and Technology. The experiments were conducted at the USFS Forest Fire Laboratory in Riverside, California. The experiments measured the ignition of chamise (Adenostoma fasciculatum) crown fuel held above a surface fire spreading through excelsior fuel. Cases with different crown fuel bulk densities, crown fuel base heights, and imposed wind speeds were considered. Cold-flow simulations yielded wind speed profiles that closely matched the experimental measurements. Next, fire simulations with only the surface fuel were conducted to verify the rate of spread while factors such as substrate properties were varied. Finally, simulations with both a surface fuel and a crown fuel were completed. Examination of specific surface fire characteristics (rate of spread, flame angle, etc.) and the corresponding experimental surface fire behavior provided a basis for comparison of the factors most responsible for transition from a surface fire to the raised fuel ignition. The rate of spread was determined by tracking the flame in the Smokeview animations using a tool developed for tracking an actual flame in a video. WFDS simulations produced results in both surface fire spread and raised fuel bed ignition which closely matched the trends reported in the laboratory experiments.

The use of fuel breaks in landscape fire management

USGS Publications Warehouse

Agee, James K.; Bahro, Berni; Finney, Mark A.; Omi, Philip N.; Sapsis, David B.; Skinner, Carl N.; Van Wagtendonk, Jan W.; Weatherspoon, C. Phillip

2000-01-01

Shaded fuelbreaks and larger landscape fuel treatments, such as prescribed fire, are receiving renewed interest as forest protection strategies in the western United States. The effectiveness of fuelbreaks remains a subject of debate because of differing fuelbreak objectives, prescriptions for creation and maintenance, and their placement in landscapes with differing fire regimes. A well-designed fuelbreak will alter the behavior of wildland fire entering the fuel-altered zone. Both surface and crown fire behavior may be reduced. Shaded fuelbreaks must be created in the context of the landscape within which they are placed. No absolute standards for fuelbreak width or fuel reduction are possible, although recent proposals for forested fuelbreaks suggest 400 m wide bands where surface fuels are reduced and crown fuels are thinned. Landscape-level treatments such as prescribed fire can use shaded fuelbreaks as anchor points, and extend the zone of altered fire behavior to larger proportions of the landscape. Coupling fuelbreaks with area-wide fuel treatments can reduce the size, intensity, and effects of wildland fires.

Toward improving our application and understanding of crown fire behavior

Treesearch

Martin E. Alexander; Miguel G. Cruz; Nicole M. Vaillant

2014-01-01

The suggestion has been made that most wildland fire operations personnel base their expectations of how a fire will behave largely on experience and, to a lesser extent, on guides to predicting fire behavior (Burrows 1984). Experienced judgment is certainly needed in any assessment of wildland fire potential but it does have its limitations. The same can be said for...

Putting out fire with gasoline: pitfalls in the silvicultural treatment of canopy fuels

Treesearch

Christopher R. Keyes; J. Morgan Varner

2007-01-01

There is little question that forest stand structure is directly related to fire behavior, and that canopy fuel structure may be altered using silvicultural methods to successfully modify forest fire behavior and reduce susceptibility to crown fire initiation and spread. Silvicultural treatments can remediate hazardous stand structures that have developed as a result...

[Vertical distribution of fuels in Pinus yunnanensis forest and related affecting factors].

PubMed

Wang, San; Niu, Shu-Kui; Li, De; Wang, Jing-Hua; Chen, Feng; Sun, Wu

2013-02-01

In order to understand the effects of fuel loadings spatial distribution on forest fire kinds and behaviors, the canopy fuels and floor fuels of Pinus yunnanensis forests with different canopy density, diameter at breast height (DBH), tree height, and stand age and at different altitude, slope grade, position, and aspect in Southwest China were taken as test objects, with the fuel loadings and their spatial distribution characteristics at different vertical layers compared and the fire behaviors in different stands analyzed. The relationships between the fuel loadings and the environmental factors were also analyzed by canonical correspondence analysis (CCA). In different stands, there existed significant differences in the vertical distribution of fuels. Pinus yunnanensis-Qak-Syzygium aromaticum, Pinus yunnanensis-oak, and Pinus yunnanensis forests were likely to occur floor fire but not crown fire, while Pinus yunnanensis-Platycladus orientalis, Pinus yunnanensis-Keteleeria fortune, and Keteleeria fortune-Pinus yunnanensis were not only inclined to occur floor fire, but also, the floor fire could be easily transformed into crown fire. The crown fuels were mainly affected by the stand age, altitude, DBH, and tree height, while the floor fuels were mainly by the canopy density, slope grade, altitude, and stand age.

Fuels planning: science synthesis and integration; forest structure and fire hazard fact sheet 02: fire hazard

Treesearch

Rocky Mountain Research Station USDA Forest Service

2004-01-01

Fire hazard reflects the potential fire behavior and magnitude of effects as a function of fuel conditions. This fact sheet discusses crown fuels, surface fuels, and ground fuels and their contribution and involvement in wildland fire.Other publications in this series...

Fire behavior in masticated fuels: a review

Treesearch

Jesse K. Kreye; Nolan W. Brewer; Penelope Morgan; J. Morgan Varner; Alistair M.S. Smith; Chad M. Hoffman; Roger D. Ottmar

2014-01-01

Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity, but fuel models do not exist for predicting fire behavior in these fuel types. Recent fires burning in masticated fuels have behaved in unexpected and contradictory ways, likely...

Surface fire intensity influences simulated crown fire behavior in lodgepole pine forests with recent mountain pine beetle-caused tree mortality

Treesearch

Chad M. Hoffman; Penelope Morgan; William Mell; Russell Parsons; Eva Strand; Steve Cook

2013-01-01

Recent bark beetle outbreaks have had a significant impact on forests throughout western North America and have generated concerns about interactions and feedbacks between beetle attacks and fire. However, research has been hindered by a lack of experimental studies and the use of fire behavior models incapable of accounting for the heterogeneous fuel complexes. We...

Do mountain pine beetle outbreaks change the probability of active crown fire in lodgepole pine forests?

Treesearch

W. Matt Jolly; Russell Parsons; J. Morgan Varner; Bret W. Butler; Kevin C. Ryan; Corey L. Gucker

2012-01-01

An expansive mountain pine beetle (MPB) epidemic is currently impacting North American forests (Raffa et al. 2008). As beetle-attacked trees die, lose their needles, and eventually fall to the ground, there are substantial changes in stand structure. These fuel changes likely affect both surface and crown fire behavior, but there is not yet a consensus among experts...

Extreme Fire Severity Patterns in Topographic, Convective and Wind-Driven Historical Wildfires of Mediterranean Pine Forests

PubMed Central

Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

2014-01-01

Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme severity wildfires. PMID:24465492

Extreme fire severity patterns in topographic, convective and wind-driven historical wildfires of Mediterranean pine forests.

PubMed

Lecina-Diaz, Judit; Alvarez, Albert; Retana, Javier

2014-01-01

Crown fires associated with extreme fire severity are extremely difficult to control. We have assessed fire severity using differenced Normalized Burn Ratio (dNBR) from Landsat imagery in 15 historical wildfires of Pinus halepensis Mill. We have considered a wide range of innovative topographic, fuel and fire behavior variables with the purposes of (1) determining the variables that influence fire severity patterns among fires (considering the 15 wildfires together) and (2) ascertaining whether different variables affect extreme fire severity within the three fire types (topographic, convective and wind-driven fires). The among-fires analysis showed that fires in less arid climates and with steeper slopes had more extreme severity. In less arid conditions there was more crown fuel accumulation and closer forest structures, promoting high vertical and horizontal fuel continuity and extreme fire severity. The analyses carried out for each fire separately (within fires) showed more extreme fire severity in areas in northern aspects, with steeper slopes, with high crown biomass and in climates with more water availability. In northern aspects solar radiation was lower and fuels had less water limitation to growth which, combined with steeper slopes, produced more extreme severity. In topographic fires there was more extreme severity in northern aspects with steeper slopes and in areas with more water availability and high crown biomass; in convection-dominated fires there was also more extreme fire severity in northern aspects with high biomass; while in wind-driven fires there was only a slight interaction between biomass and water availability. This latter pattern could be related to the fact that wind-driven fires spread with high wind speed, which could have minimized the effect of other variables. In the future, and as a consequence of climate change, new zones with high crown biomass accumulated in non-common drought areas will be available to burn as extreme severity wildfires.

Characterizing crown fuel distribution for conifers in the interior western United States

Treesearch

Seth Ex; Frederick W. Smith; Tara Keyser

2015-01-01

Canopy fire hazard evaluation is essential for prioritizing fuel treatments and for assessing potential risk to firefighters during suppression activities. Fire hazard is usually expressed as predicted potential fire behavior, which is sensitive to the methodology used to quantitatively describe fuel profiles: methodologies that assume that fuel is distributed...

What kind of cutting and thinning can prevent crown fires?

Treesearch

Mick Harrington

2008-01-01

Many land managers are attempting to lessen the probability of severe wildfire behavior and impacts, especially near communities, by manipulating canopy and surface fuel characteristics. Various interest groups have questioned the value of fuels treatments. In reality, apart from fire exposure when a real fire went through a treated stand, effectiveness of fuel...

Characterizing fire behavior from laboratory burns of multi-aged, mixed-conifer masticated fuels in the western United States

Treesearch

Faith Ann Heinsch; Pamela G. Sikkink; Helen Y. Smith; Molly L. Retzlaff

2018-01-01

Mastication is the process of chipping or shredding components of the tree canopy or above-ground vegetation to reduce the canopy, alter fire spread rates, and reduce crown fire potential. Mastication as a fuel treatment, either alone or in combination with prescribed fire, has been the subject of much research. This research has shown that modeling expected fire...

Effectiveness of mechanical thinning and prescribed burning on fire behavior in Pinus nigra forests in NE Spain.

PubMed

Piqué, Míriam; Domènech, Rut

2018-03-15

Fuel treatments can mitigate present and future impacts of climate change by reducing fire intensity and severity. In recent years, Pinus nigra forests in the Mediterranean basin have been dramatically affected by the new risk of highly intense and extreme fires and its distribution area has been reduced. New tools are necessary for assessing the management of these forests so they can adapt to the challenges to come. Our main goal was to evaluate the effects of different fuel treatments on Mediterranean Pinus nigra forests. We assessed the forest response, in terms of forest structure and fire behavior, to different intensities of low thinning treatments followed by different slash prescriptions (resulting in: light thinning and lop and scatter; light thinning and burn; heavy thinning and lop and scatter; heavy thinning and burn; and, untreated control). Treatments that used fire to decrease the resulting slash were the most effective for reducing active crown fires decreasing the rate of spread and flame length more than 89%. Low thinning had an effect on torching potential, but there was no difference between intensities of thinning. Only an outcoming crown fire could spread actively if it was sustained by a high-enough constant wind speed and enough surface fuel load. Overall, treatments reduce fire intensity and treated areas have a more homogenous fire behavior response than untreated areas. This provides opportunities to extinguish the fire and reduce the probability of trees dying from the fire. It would be helpful to include ecological principles and fire behavior criteria in silvicultural treatment guidelines in order to perform more efficient management techniques in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

Changes in canopy fuels and fire behavior after ponderosa pine restoration treatments: A landscape perspective

Treesearch

J. P. Roccaforte; P. Z. Fule

2008-01-01

(Please note, this is an abstract only) We modeled crown fire behavior and assessed changes in canopy fuels before and after the implementation of restoration treatments in a ponderosa pine landscape at Mt. Trumbull, Arizona. We measured 117 permanent plots before (1996/1997) and after (2003) thinning and burning treatments. The plots are evenly distributed across the...

An investigation of crown fuel bulk density effects on the dynamics of crown fire initiation in shrublands

Treesearch

Watcharapong Tachajapong; Jesse Lozano; Shankar Mahalingam; Xiangyang Zhou; David R. Weise

2008-01-01

Crown fire initiation is studied by using a simple experimental and detailed physical modeling based on Large Eddy Simulation (LES). Experiments conducted thus far reveal that crown fuel ignition via surface fire occurs when the crown base is within the continuous flame region and does not occur when the crown base is located in the hot plume gas region of the surface...

Incorporating field wind data into FIRETEC simulations of the International Crown Fire Modeling Experiment (ICFME): preliminary lessons learned

Treesearch

Rodman Linn; Kerry Anderson; Judith Winterkamp; Alyssa Broos; Michael Wotton; Jean-Luc Dupuy; Francois Pimont; Carleton Edminster

2012-01-01

Field experiments are one way to develop or validate wildland fire-behavior models. It is important to consider the implications of assumptions relating to the locality of measurements with respect to the fire, the temporal frequency of the measured data, and the changes to local winds that might be caused by the experimental configuration. Twenty FIRETEC simulations...

Experimental and numerical modeling of shrub crown fire initiation

Treesearch

Watcharapong Tachajapong; Jesse Lozano; Shakar Mahalingam; Xiangyang Zhou; David Weise

2009-01-01

The transition of fire from dry surface fuels to wet shrub crown fuels was studied using laboratory experiments and a simple physical model to gain a better understanding of the transition process. In the experiments, we investigated the effects of varying vertical distances between surface and crown fuels (crown base height), and of the wind speed on crown fire...

Simulated western spruce budworm defoliation reduces torching and crowning potential: A sensitivity analysis using a physics-based fire model

Treesearch

Gregory M. Cohn; Russell A. Parsons; Emily K. Heyerdahl; Daniel G. Gavin; Aquila Flower

2014-01-01

The widespread, native defoliator western spruce budworm (Choristoneura occidentalis Freeman) reduces canopy fuels, which might affect the potential for surface fires to torch (ignite the crowns of individual trees) or crown (spread between tree crowns). However, the effects of defoliation on fire behaviour are poorly understood. We used a physics-based fire model to...

Estimating canopy fuels in conifer forests

Treesearch

Joe H. Scott; Elizabeth D. Reinhardt

2002-01-01

Crown fires occur in a variety of coniferous forest types (Agee 1993), including some that are not historically prone to crown fire, such as ponderosa pine (Mutch and others 1993). The head fire spread rate of a crown fire is usually several times faster than that of a surface fire burning under the same conditions, which leads to a significant increase in the number...

Wind tunnel experiments to study chaparral crown fires

Treesearch

Jeanette Cobian-Iñiguez; AmirHessam Aminfar; Joey Chong; Gloria Burke; Albertina Zuniga; David R. Weise; Marko Princevac

2017-01-01

The present protocol presents a laboratory technique designed to study chaparral crown fire ignition and spread. Experiments were conducted in a low velocity fire wind tunnel where two distinct layers of fuel were constructed to represent surface and crown fuels in chaparral. Chamise, a common chaparral shrub, comprised the live crown layer. The dead fuel surface layer...

Fuel and fire behavior prediction in big sagebrush

Treesearch

James K. Brown

1982-01-01

Relationships between height of big sagebrush and crown area, fuel loading, bulk density, size distribution of foliage and stemwood, and fraction dead stemwood are presented. Based upon these relationships, modeled rate-of-fire spread and fireline intensity are shown for sagebrush ranging in height from 20 to 120 em and in coverage from 10 to 40 percent. Verification...

Predicting mortality of ponderosa pine regeneration after prescribed fire in the Black Hills, South Dakota, USA

Treesearch

Mike Battaglia; Frederick W. Smith; Wayne D. Shepperd

2009-01-01

Reduction of crown fire hazard in Pinus ponderosa forests in the Black Hills, SD, often focuses on the removal of overstorey trees to reduce crown bulk density. Dense ponderosa pine regeneration establishes several years after treatment and eventually increases crown fire risk if allowed to grow. Using prescribed fire to control this regeneration is...

Influence of bark beetle-caused mortality on fuel loadings and crown fire hazard in southwestern ponderosa pine stands

Treesearch

Chad M. Hoffman; Joel D. McMillin; Carolyn Hull Sieg; Peter Z. Fule

2012-01-01

Bark beetles (Coleoptera: Scolytinae) are important biotic agents of conifer mortality in forests of western North America (Furniss and Carolin 1977) and play an important role in the disturbance ecology of these ecosystems (Fettig and others 2007). Bark beetle outbreaks affect subsequent fire behavior in part by influencing the spatial...

Modelling available crown fuel for Pinus pinaster Ait. stands in the "Cazorla, Segura and Las Villas Natural Park" (Spain).

PubMed

Molina, Juan Ramón; Rodríguez y Silva, Francisco; Mérida, Enrique; Herrera, Miguel Ángel

2014-11-01

One of the main limiting aspects in the application of crown fire models at landscape scale has been the uncertainty derived to describe canopy fuel stratum. Available crown fuel and canopy bulk density are essential in order to simulate crown fire behaviour and are of potential use in the evaluation of silvicultural treatments. Currently, the more accurate approach to estimate these parameters is to develop allometric models from common stand inventory data. In this sense, maritime pine (Pinus pinaster Aiton) trees were destructively sampled in the South of the Iberian Peninsula, covering natural and artificial stands. Crown fine fuel was separated into size classes and allometric equations that estimate crown fuel load by biomass fractions were developed. Available crown fuel was determined according to the fuel load differences between un-burned and burned trees with similar characteristics. Taking our destructive post-fire inventory into account, available crown fuel was estimated as the sum of needles biomass, 87.63% of the twigs biomass and 62.79% of the fine branches biomass. In spite of the differences between natural and artificial stands, generic models explained 82% (needles biomass), 89% (crown fuel), 92% (available crown fuel) and 94% (canopy bulk density) of the observed variation. Inclusion of the fitted models in fire management decision-making can provide a decision support system for assessing the potential crown fire of different silvicultural alternatives. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synergistic interactions between leaf beetle herbivory and fire enhance tamarisk (Tamarix spp.) mortality

USGS Publications Warehouse

Drus, Gail M.; Dudley, Tom L.; Antonio, Carla M.; Even, Thomas J.; Brooks, Matt L.; Matchett, J.R.

2014-01-01

The combined effects of herbivory and fire on plant mortality were investigated using prescribed burns of tamarisk (Tamarix ramosissima Lebed) exposed to herbivory by the saltcedar leaf beetle (Chrysomelidae: Diorhabda carinulata Desbrocher). Tamarix stands in the Humboldt Sink (NV, USA) were divided into three treatments: summer burn (August 2006), fall burn (October 2006) and control (unburned), and litter depth was manipulated to vary fire intensity within burn seasons. A gradient of existing herbivory impact was described with three plant condition metrics prior to fire: reduced proportions of green canopy, percent root crown starch sampled at the height of the growing season (August 2006), and percent root crown starch measured during dormancy (December 2006). August root crown starch concentration and proportion green canopy were strongly correlated, although the proportion green canopy predicted mortality better than August root crown starch. December root crown starch concentration was more depleted in unburned trees and in trees burned during the summer than in fall burn trees. Mortality in summer burned trees was higher than fall burned trees due to higher fire intensity, but December root crown starch available for resprouting in the spring was also lower in summer burned trees. The greatest mortality was observed in trees with the lowest December root crown starch concentration which were exposed to high fire intensity. Disproportionate changes in the slope and curvature of prediction traces as fire intensity and December starch reach reciprocal maximum and minimum levels indicate that beetle herbivory and fire intensity are synergistic.

Uncertainty in Wildfire Behavior

NASA Astrophysics Data System (ADS)

Finney, M.; Cohen, J. D.

2013-12-01

The challenge of predicting or modeling fire behavior is well recognized by scientists and managers who attempt predictions of fire spread rate or growth. At the scale of the spreading fire, the uncertainty in winds, moisture, fuel structure, and fire location make accurate predictions difficult, and the non-linear response of fire spread to these conditions means that average behavior is poorly represented by average environmental parameters. Even more difficult are estimations of threshold behaviors (e.g. spread/no-spread, crown fire initiation, ember generation and spotting) because the fire responds as a step-function to small changes in one or more environmental variables, translating to dynamical feedbacks and unpredictability. Recent research shows that ignition of fuel particles, itself a threshold phenomenon, depends on flame contact which is absolutely not steady or uniform. Recent studies of flame structure in both spreading and stationary fires reveals that much of the non-steadiness of the flames as they contact fuel particles results from buoyant instabilities that produce quasi-periodic flame structures. With fuel particle ignition produced by time-varying heating and short-range flame contact, future improvements in fire behavior modeling will likely require statistical approaches to deal with the uncertainty at all scales, including the level of heat transfer, the fuel arrangement, and weather.

Fire structures pine serotiny at different scales.

PubMed

Hernández-Serrano, Ana; Verdú, Miguel; González-Martínez, Santiago C; Pausas, Juli G

2013-12-01

Serotiny (delayed seed release with the consequent accumulation of a canopy seedbank) confers fitness benefits in environments with crown-fire regimes. Thus, we predicted that serotiny level should be higher in populations recurrently subjected to crown-fires than in populations where crown-fires are rare. In addition, under a high frequency of fires, space and resources are recurrently available, permitting recruitment around each mother to follow the seed rain shadow. Thus, we also predicted spatial aggregation of serotiny within populations. We compared serotiny, considering both the proportion and the age of serotinous cones, in populations living in contrasting fire regimes for two iconic Mediterranean pine species (Pinus halepensis, P. pinaster). We framed our results by quantitatively comparing the strength of the fire-serotiny relationship with previous studies worldwide. For the two species, populations living under high crown-fire recurrence regimes had a higher serotiny level than those populations where the recurrence of crown-fires was low. For P. halepensis (the species with higher serotiny), populations in high fire recurrence regimes had higher fine-scale spatial aggregation of serotiny than those inhabiting low fire recurrence systems. The strength of the observed fire-serotiny relationship in P. halepensis is among the highest in published literature. Fire regime shapes serotiny level among populations, and in populations with high serotiny, recurrent fires maintain a significant spatial structure for this trait. Consequently, fire has long-term evolutionary implications at different scales, emphasizing its prominent role in shaping the ecology of pines.

Using stand-level optimization to reduce crown fire hazard

Treesearch

David H. Graetz; John Sessions; Steven L. Garman

2007-01-01

This study evaluated the ability to generate prescriptions for a wide variety of stands when the goal is to reduce crown fire potential. Forest managers charged with reducing crown fire potential while providing for commodity and ecological production have been hampered by the complexity of possible management options. A program called Stand-Level Optimization with...

Development of post-fire crown damage mortality thresholds in ponderosa pine

Treesearch

James F. Fowler; Carolyn Hull Sieg; Joel McMillin; Kurt K. Allen; Jose F. Negron; Linda L. Wadleigh; John A. Anhold; Ken E. Gibson

2010-01-01

Previous research has shown that crown scorch volume and crown consumption volume are the major predictors of post-fire mortality in ponderosa pine. In this study, we use piecewise logistic regression models of crown scorch data from 6633 trees in five wildfires from the Intermountain West to locate a mortality threshold at 88% scorch by volume for trees with no crown...

Experimental modeling of crown fire initiation in open and closed shrubland systems

Treesearch

W. Tachajapong; S. Lozano; S. Mahalingam; D.R. Weise

2014-01-01

The transition of surface fire to live shrub crown fuels was studied through a simplified laboratory experiment using an open-topped wind tunnel. Respective surface and crown fuels used were excelsior (shredded Populus tremuloides wood) and live chamise (Adenostoma fasciculatum, including branches and foliage). A high crown fuel...

Mechanical mastication as a fuels treatment in southeastern forests

Treesearch

Jesse K. Kreye; J. Morgan Varner; Leda N. Kobziar

2016-01-01

Mastication is an increasingly common fuels treatment that redistributes ‘‘ladder’’ fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity. Despite its widespread adoption, it remains unclear how mastication impacts fuels, fire behavior, or plant communities  across Southeastern forest ecosystems. We evaluated these...

[Influence of coping material selection and porcelain firing on marginal and internal fit of computer-aided design/computer- aided manufacturing of zirconia and titanium ceramic implant-supported crowns].

PubMed

Cuiling, Liu; Liyuan, Yang; Xu, Gao; Hong, Shang

2016-06-01

This study aimed to investigate the influence of coping material and porcelain firing on the marginal and internal fit of computer-aided design/computer-aided manufacturing (CAD/CAM) of zirconia ceramic implant- and titanium ceramic implant-supported crowns. Zirconia ceramic implant (group A, n = 8) and titanium metal ceramic implant-supported crowns (group B, n = 8) were produced from copings using the CAD/CAM system. The marginal and internal gaps of the copings and crowns were measured by using a light-body silicone replica technique combined with micro-computed tomography scanning to obtain a three-dimensional image. Marginal gap (MG), horizontal marginal discrepancy (HMD), and axial wall (AW) were measured. Statistical analyses were performed using SPSS 17.0. Prior to porcelain firing, the measurements for MG, HMD, and AW of copings in group A were significantly larger than those in group B (P < 0.05). After porcelain firing, the measurements for MG of crowns in group A were smaller than those in group B (P < 0.05), whereas HMD and AW showed no significant difference between the two groups (P > 0.05). Porcelain firing significantly reduced MG (P < 0.05) in group A but significantly increased MG, HMD, and AW in group B (P < 0.05) HMD and AW were not influenced by porcelain firing in group A (P > 0.05). The marginal fits of CAD/CAM zirconia ceramic implant-supported crowns were superior to those of CAD/CAM titanium ceramic-supported crowns. The fits of both the CAD/CAM zirconia ceramic implant- and titanium ceramic implant-supported crowns were obviously influenced by porcelain firing.

Critical mass flux for flaming ignition of wood as a function of external radiant heat flux and moisture content

Treesearch

S. McAllister; M. Finney; J. Cohen

2011-01-01

Extreme weather often contributes to crown fires, where the fire spreads from one tree crown to the next as a series of piloted ignitions. An important aspect in predicting crown fires is understanding the ignition of fuel particles. The ignition criterion considered in this work is the critical mass flux criterion - that a sufficient amount of pyrolysis gases must be...

Critical mass flux for flaming ignition of dead, dry wood as a function of exernal radiant heat flux

Treesearch

Sara McAllister; Mark Finney; Jack Cohen

2010-01-01

Extreme weather often contributes to crown fires, where the fire spreads from one tree crown to the next as a series of piloted ignitions. An important aspect in predicting crown fires is understanding the ignition of fuel particles. The ignition criterion considered in this work is the critical mass flux criterion - that a sufficient amount of pyrolysis gases must be...

[Influence of different designs and porcelain/glaze firing on the marginal and internal fit of implant-supported zirconia crowns].

PubMed

Cuiling, Liu; Xu, Gao; Yuping, Qi; Liyuan, Yang

2016-02-01

This study investigated the influence of different designs and porcelain/glaze firing on the marginal and internal fit of three kinds of computer aided design/computer aided manufacturing (CAD/CAM) zirconia ceramic implant-supported crowns. Three groups of zirconia ceramic implant-supported crowns with different designs were produced from copings by using a Cercon CAD/CAM system (n = 8). The first two groups comprised double-layer crowns (zirconia coping + veneer) with regular (Group A) and full circumferential zirconia-collar marginal designs (Group B). The third group was composed of anatomic single-layer zirconia crowns without cores (Group C). Initially, the marginal and internal gaps of the copings and crowns were individually replicated by light-body silicon and then measured by micro-computed tomography scanning before and after porcelain/glaze firing. Five measurements were employed: vertical marginal gap (MG); horizontal marginal discrepancy (HMD); chamfer area (CA); axial wall (AW); and axial-occlusal transition area (AOT). Statistical analyses were performed by SPSS 17.0. HMD measurements in Group A were statistically higher than those in Groups B and C (P < 0.05), regardless of whether the values were obtained before or after porcelain/glaze firing. By contrast, the HIMD measurements in Groups B and C showed no significant difference (P > 0.05). Moreover, no differences were noted in MG, CA, AW, and AOT among the three groups (P > 0.05). All the measurements in the three groups showed no significant change after porcelain/glaze firing (P > 0.05), except for MG in Group A, which significantly decreased (P < 0.05). The marginal fits of the double-layer crowns with full circumferential zirconia-collar and the anatomic single-layer zirconia crowns were superior to that of the double-layer crowns with regular margins. The MG of the crowns with regular margins was obviously influenced by porcelain firing.

Seasonal Fluctuation in Moisture Content of Pine Foliage

Treesearch

Von J. Johnson

1966-01-01

Green or living fuels, particularly pine crowns, are commonly consumed by forest fires burning hot, windy weather. In some cases the pine crown fire has been known to burn ahead of surface-burning fire for some distance before dropping to the ground.

Using High Spatial Resolution Satellite Imagery to Map Forest Burn Severity Across Spatial Scales in a Pine Barrens Ecosystem

NASA Technical Reports Server (NTRS)

Meng, Ran; Wu, Jin; Schwager, Kathy L.; Zhao, Feng; Dennison, Philip E.; Cook, Bruce D.; Brewster, Kristen; Green, Timothy M.; Serbin, Shawn P.

2017-01-01

As a primary disturbance agent, fire significantly influences local processes and services of forest ecosystems. Although a variety of remote sensing based approaches have been developed and applied to Landsat mission imagery to infer burn severity at 30 m spatial resolution, forest burn severity have still been seldom assessed at fine spatial scales (less than or equal to 5 m) from very-high-resolution (VHR) data. We assessed a 432 ha forest fire that occurred in April 2012 on Long Island, New York, within the Pine Barrens region, a unique but imperiled fire-dependent ecosystem in the northeastern United States. The mapping of forest burn severity was explored here at fine spatial scales, for the first time using remotely sensed spectral indices and a set of Multiple Endmember Spectral Mixture Analysis (MESMA) fraction images from bi-temporal - pre- and post-fire event - WorldView-2 (WV-2) imagery at 2 m spatial resolution. We first evaluated our approach using 1 m by 1 m validation points at the sub-crown scale per severity class (i.e. unburned, low, moderate, and high severity) from the post-fire 0.10 m color aerial ortho-photos; then, we validated the burn severity mapping of geo-referenced dominant tree crowns (crown scale) and 15 m by 15 m fixed-area plots (inter-crown scale) with the post-fire 0.10 m aerial ortho-photos and measured crown information of twenty forest inventory plots. Our approach can accurately assess forest burn severity at the sub-crown (overall accuracy is 84% with a Kappa value of 0.77), crown (overall accuracy is 82% with a Kappa value of 0.76), and inter-crown scales (89% of the variation in estimated burn severity ratings (i.e. Geo-Composite Burn Index (CBI)). This work highlights that forest burn severity mapping from VHR data can capture heterogeneous fire patterns at fine spatial scales over the large spatial extents. This is important since most ecological processes associated with fire effects vary at the less than 30 m scale and VHR approaches could significantly advance our ability to characterize fire effects on forest ecosystems.

Using high spatial resolution satellite imagery to map forest burn severity across spatial scales in a Pine Barrens ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Ran; Wu, Jin; Schwager, Kathy L.

As a primary disturbance agent, fire significantly influences local processes and services of forest ecosystems. Although a variety of remote sensing based approaches have been developed and applied to Landsat mission imagery to infer burn severity at 30 m spatial resolution, forest burn severity have still been seldom assessed at fine spatial scales (≤ 5 m) from very-high-resolution (VHR) data. Here we assessed a 432 ha forest fire that occurred in April 2012 on Long Island, New York, within the Pine Barrens region, a unique but imperiled fire-dependent ecosystem in the northeastern United States. The mapping of forest burn severitymore » was explored here at fine spatial scales, for the first time using remotely sensed spectral indices and a set of Multiple Endmember Spectral Mixture Analysis (MESMA) fraction images from bi-temporal — pre- and post-fire event — WorldView-2 (WV-2) imagery at 2 m spatial resolution. We first evaluated our approach using 1 m by 1 m validation points at the sub-crown scale per severity class (i.e. unburned, low, moderate, and high severity) from the post-fire 0.10 m color aerial ortho-photos; then, we validated the burn severity mapping of geo-referenced dominant tree crowns (crown scale) and 15 m by 15 m fixed-area plots (inter-crown scale) with the post-fire 0.10 m aerial ortho-photos and measured crown information of twenty forest inventory plots. Our approach can accurately assess forest burn severity at the sub-crown (overall accuracy is 84% with a Kappa value of 0.77), crown (overall accuracy is 82% with a Kappa value of 0.76), and inter-crown scales (89% of the variation in estimated burn severity ratings (i.e. Geo-Composite Burn Index (CBI)). Lastly, this work highlights that forest burn severity mapping from VHR data can capture heterogeneous fire patterns at fine spatial scales over the large spatial extents. This is important since most ecological processes associated with fire effects vary at the < 30 m scale and VHR approaches could significantly advance our ability to characterize fire effects on forest ecosystems.« less

Using high spatial resolution satellite imagery to map forest burn severity across spatial scales in a Pine Barrens ecosystem

DOE PAGES

Meng, Ran; Wu, Jin; Schwager, Kathy L.; ...

2017-01-21

As a primary disturbance agent, fire significantly influences local processes and services of forest ecosystems. Although a variety of remote sensing based approaches have been developed and applied to Landsat mission imagery to infer burn severity at 30 m spatial resolution, forest burn severity have still been seldom assessed at fine spatial scales (≤ 5 m) from very-high-resolution (VHR) data. Here we assessed a 432 ha forest fire that occurred in April 2012 on Long Island, New York, within the Pine Barrens region, a unique but imperiled fire-dependent ecosystem in the northeastern United States. The mapping of forest burn severitymore » was explored here at fine spatial scales, for the first time using remotely sensed spectral indices and a set of Multiple Endmember Spectral Mixture Analysis (MESMA) fraction images from bi-temporal — pre- and post-fire event — WorldView-2 (WV-2) imagery at 2 m spatial resolution. We first evaluated our approach using 1 m by 1 m validation points at the sub-crown scale per severity class (i.e. unburned, low, moderate, and high severity) from the post-fire 0.10 m color aerial ortho-photos; then, we validated the burn severity mapping of geo-referenced dominant tree crowns (crown scale) and 15 m by 15 m fixed-area plots (inter-crown scale) with the post-fire 0.10 m aerial ortho-photos and measured crown information of twenty forest inventory plots. Our approach can accurately assess forest burn severity at the sub-crown (overall accuracy is 84% with a Kappa value of 0.77), crown (overall accuracy is 82% with a Kappa value of 0.76), and inter-crown scales (89% of the variation in estimated burn severity ratings (i.e. Geo-Composite Burn Index (CBI)). Lastly, this work highlights that forest burn severity mapping from VHR data can capture heterogeneous fire patterns at fine spatial scales over the large spatial extents. This is important since most ecological processes associated with fire effects vary at the < 30 m scale and VHR approaches could significantly advance our ability to characterize fire effects on forest ecosystems.« less

Effects of prescribed fire on fuels, vegetation, and Golden-cheeked Warbler (Setophaga chrysoparia) demographics in Texas juniper-oak woodlands

Treesearch

Jennifer L. Reidy; Frank R., III Thompson; Carl Schwope; Scott Rowin; James M. Mueller

2016-01-01

The Golden-cheeked Warbler (Setophaga chrysoparia) is an endangered songbird that breeds in mature juniper-oak woodlands restricted to Central Texas. This habitat is increasingly susceptible to crown fire due to climate change, land use change, and fire suppression. Prescribed fire is a potential tool to reduce the risk of crown fire and may be a...

The influence of prefire tree growth and crown condition on postfire mortality of sugar pine following prescribed fire in Sequoia National Park

USGS Publications Warehouse

Nesmith, Jonathan C. B.; Das, Adrian J.; O'Hara, Kevin L.; van Mantgem, Phillip J.

2015-01-01

Tree mortality is a vital component of forest management in the context of prescribed fires; however, few studies have examined the effect of prefire tree health on postfire mortality. This is especially relevant for sugar pine (Pinus lambertiana Douglas), a species experiencing population declines due to a suite of anthropogenic factors. Using data from an old-growth mixed-conifer forest in Sequoia National Park, we evaluated the effects of fire, tree size, prefire radial growth, and crown condition on postfire mortality. Models based only on tree size and measures of fire damage were compared with models that included tree size, fire damage, and prefire tree health (e.g., measures of prefire tree radial growth or crown condition). Immediately following the fire, the inclusion of different metrics of prefire tree health produced variable improvements over the models that included only tree size and measures of fire damage, as models that included measures of crown condition performed better than fire-only models, but models that included measures of prefire radial growth did not perform better. However, 5 years following the fire, sugar pine mortality was best predicted by models that included measures of both fire damage and prefire tree health, specifically, diameter at breast height (DBH, 1.37 m), crown scorch, 30-year mean growth, and the number of sharp declines in growth over a 30-year period. This suggests that factors that influence prefire tree health (e.g., drought, competition, pathogens, etc.) may partially determine postfire mortality, especially when accounting for delayed mortality following fire.

Critical mass flux for flaming ignition of dead, dry wood as a function of external radiant heat flux and oxidizer flow velocity

Treesearch

Sara McAllister; Mark Finney; Jack Cohen

2010-01-01

Extreme weather often contributes to crown fires, where the fire spreads from one tree crown to the next as a series of piloted ignitions. An important aspect in predicting crown fires is understanding the ignition of fuel particles. The ignition criterion considered in this work is the critical mass flux criterion – that a sufficient amount of pyrolysis gases must be...

Effect of Crystallization Firing on Marginal Gap of CAD/CAM Fabricated Lithium Disilicate Crowns.

PubMed

Gold, Steven A; Ferracane, Jack L; da Costa, Juliana

2018-01-01

To evaluate the marginal gaps of CAD/CAM (CEREC 3) produced crowns made from leucite-reinforced glass-ceramic (IPS Empress CAD) blocks (LG), and lithium-disilicate (IPS e.max CAD) blocks before (LD-B), and after (LD-A) crystallization firing. A human molar tooth (#19) was mounted with adjacent teeth on a typodont and prepared for a full-coverage ceramic crown. The typodont was assembled in the mannequin head to simulate clinical conditions. After tooth preparation 15 individual optical impressions were taken by the same operator using titanium dioxide powder and a CEREC 3 camera per manufacturer's instructions. One operator designed and machined the crowns in leucite-reinforced glass-ceramic blocks (n = 5) and lithium-disilicate blocks (n = 10) using the CEREC 3 system. The crowns were rigidly seated on the prepared tooth, and marginal gaps (μm) were measured with an optical microscope (500×) at 12 points, 3 on each of the M, B, D, and L surfaces of the leucite-reinforced glass-ceramic crowns and the lithium-disilicate crowns before and after crystallization firing. Results were analyzed by two-way ANOVA followed by a Tukey's post hoc multiple comparison test (α = 0.05). The overall mean marginal gaps (μm) for the crowns evaluated were: LG = 49.2 ± 5.5, LD-B = 42.9 ± 12.2, and LD-A = 57.2 ± 16.0. The marginal gaps for LG and LD-B were not significantly different, but both were significantly less than for LD-A. The type of ceramic material did not affect the marginal gap of CAD/CAM crowns. The crystallization firing process required for lithium-disilicate crowns resulted in a significant increase in marginal gap size, likely due to shrinkage of the ceramic during the crystallization process. The marginal gap of CAD/CAM-fabricated lithium disilicate crowns increases following crystallization firing. The marginal gap still remains within clinically acceptable parameters. © 2017 by the American College of Prosthodontists.

Crown physiology and growth of sapling longleaf pine after fire

Treesearch

Mary Anne Sword Sayer; Eric A. Kuehler

2005-01-01

Fire affects foliage and thus, whole-crown C fixation potential. When repeated throughout a rotation, therefore, fire has a potential impact on stemwood growth and C allocation among the foliage, stem and roots. Depending on frequency and intensity, prescribed fire causes foliage damage that may lead to a long-term reduction in stand growth. Past research, however, is...

Wildfire spread, hazard and exposure metric raster grids for central Catalonia.

PubMed

Alcasena, Fermín J; Ager, Alan A; Salis, Michele; Day, Michelle A; Vega-Garcia, Cristina

2018-04-01

We provide 40 m resolution wildfire spread, hazard and exposure metric raster grids for the 0.13 million ha fire-prone Bages County in central Catalonia (northeastern Spain) corresponding to node influence grid (NIG), crown fraction burned (CFB) and fire transmission to residential houses (TR). Fire spread and behavior data (NIG, CFB and fire perimeters) were generated with fire simulation modeling considering wildfire season extreme fire weather conditions (97 th percentile). Moreover, CFB was also generated for prescribed fire (Rx) mild weather conditions. The TR smoothed grid was obtained with a geospatial analysis considering large fire perimeters and individual residential structures located within the study area. We made these raster grids available to assist in the optimization of wildfire risk management plans within the study area and to help mitigate potential losses from catastrophic events.

ASTER Views California Crown Fire

NASA Image and Video Library

2010-08-03

NASA Terra spacecraft captured this image of the wildfire near Palmdale, Calif. on August 1, 2010 called the Crown fire. The burned areas appear in shades of gray in this simulated natural color image.

Characterization of convective heating in full scale wildland fires

Treesearch

Bret Butler

2010-01-01

Data collected in the International Crown Fire modeling Experiment during 1999 are evaluated to characterize the magnitude and duration of convective energy heating in full scale crown fires. To accomplish this objective data on total and radiant incident heat flux, air temperature, and horizontal and vertical gas velocities were evaluated. Total and radiant energy...

Quercus kelloggii (Newb.) sprout response to fire severity in northern California

Treesearch

Justin S. Crotteau; Martin W. Ritchie; J. Morgan Varner; John-Pascal Berrill

2015-01-01

We counted seedlings and assessed crown characteristics and abundance of fire-induced stump sprout regeneration in California black oak (Quercus kelloggii) 11 to 12 years after wildfire. Regeneration was examined across three levels of burn severity (low, moderate, and high) according to the Composite Burn Index. Fire severity affected crown width...

A strategic assessment of crown fire hazard in Montana: potential effectiveness and costs of hazard reduction treatments.

Treesearch

Carl E. Fiedler; Charles E. Keegan; Christopher W. Woodall; Todd A. Morgan

2004-01-01

Estimates of crown fire hazard are presented for existing forest conditions in Montana by density class, structural class, forest type, and landownership. Three hazard reduction treatments were evaluated for their effectiveness in treating historically fire-adapted forests (ponderosa pine (Pinus ponderosa Dougl. ex Laws.), Douglas-fir (...

Effect of a Spaced Thinning in Mature Lodgepole Pine on Within-Stand Microclimate and Fine Fuel Moisture Content

Treesearch

R. J. Whitehead; G. L. Russo; B. C. Hawkes; S. W. Taylor; B. N. Brown; H. J. Barclay; R. A. Benton

2006-01-01

Thinning mature forest stands to wide spacing is prescribed to reduce crown bulk density and likelihood of severe crown fire behaviour. However, it may adversely affect surface fuel load, moisture content and within-stand wind, which influence surface fire behaviour and crowning potential. Comparison of a mature lodgepole pine (Pinus contorta Dougl....

Surface fire effects on conifer and hardwood crowns--applications of an integral plume model

Treesearch

Matthew Dickinson; Anthony Bova; Kathleen Kavanagh; Antoine Randolph; Lawrence Band

2009-01-01

An integral plume model was applied to the problems of tree death from canopy injury in dormant-season hardwoods and branch embolism in Douglas fir (Pseudotsuga menziesii) crowns. Our purpose was to generate testable hypotheses. We used the integral plume models to relate crown injury to bole injury and to explore the effects of variation in fire...

Modification of VanWagner's canopy fire propagation model

Treesearch

James Dickinson; Andrew Robinson; Richy Harrod; Paul Gessler; Alistair Smith

2007-01-01

The conditions necessary for the combustion of canopy fuels are not well known but are assumed to be highly influenced by the volume through which the canopy fuels are dispersed, known as canopy bulk density (CBD). Propagating crown fire is defined as a continuous wall of flame from the bottom to the top of the canopy, implying crown fire propagation is actually...

Effects of Sudden Oak Death on the crown fire ignition potential of tanoak (Lithocarpus densiflorus)

Treesearch

Howard Kuljian; J. Morgan Varner

2010-01-01

In the face of the sudden oak death (SOD) epidemic, decreasing foliar moisture content (FMC) of tanoak (Lithocarpus densiflorus) has land managers, fire managers, and property owners concerned with the increased possibility of crown fire in affected areas. A need exists to link local SOD-affected foliar moisture content (FMC) values and current FMC...

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, U.S.A.

PubMed

Fraver, Shawn; Jain, Theresa; Bradford, John B; D'Amato, Anthony W; Kastendick, Doug; Palik, Brian; Shinneman, Doug; Stanovick, John

2011-09-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and wildfire-provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions.

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, USA

USGS Publications Warehouse

Fraver, S.; Jain, T.; Bradford, J.B.; D'Amato, A.W.; Kastendick, D.; Palik, B.; Shinneman, D.; Stanovick, J.

2011-01-01

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances-blowdown, salvage logging, and ildfire- provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire-severity assessments (tree-crown and forest-floor characteristics) to compare post-wildfire conditions among three treatment combinations (Blowdown-Salvage-Fire, Blowdown-Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree-crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest-floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post-disturbance management prescriptions. ?? 2011 by the Ecological Society of America.

Postfire survival and flushing in three Sierra Nevada conifers with high initial crown scorch

Treesearch

C. Hanson; M. North

2009-01-01

With growing debate over the impacts of post-fire salvage logging in conifer forests of the western USA, managers need accurate assessments of tree survival when significant proportions of the crown have been scorched. The accuracy of fire severity measurements will be affected if trees that initially appear to be fire-killed prove to be viable after longer observation...

Wind Tunnel Experiments to Study Chaparral Crown Fires.

PubMed

Cobian-Iñiguez, Jeanette; Aminfar, AmirHessam; Chong, Joey; Burke, Gloria; Zuniga, Albertina; Weise, David R; Princevac, Marko

2017-11-14

The present protocol presents a laboratory technique designed to study chaparral crown fire ignition and spread. Experiments were conducted in a low velocity fire wind tunnel where two distinct layers of fuel were constructed to represent surface and crown fuels in chaparral. Chamise, a common chaparral shrub, comprised the live crown layer. The dead fuel surface layer was constructed with excelsior (shredded wood). We developed a methodology to measure mass loss, temperature, and flame height for both fuel layers. Thermocouples placed in each layer estimated temperature. A video camera captured the visible flame. Post-processing of digital imagery yielded flame characteristics including height and flame tilt. A custom crown mass loss instrument developed in-house measured the evolution of the mass of the crown layer during the burn. Mass loss and temperature trends obtained using the technique matched theory and other empirical studies. In this study, we present detailed experimental procedures and information about the instrumentation used. The representative results for the fuel mass loss rate and temperature filed within the fuel bed are also included and discussed.

Influence of Crown Biomass Estimators and Distribution on Canopy Fuel Characteristics in Ponderosa Pine Stands of the Black Hills

Treesearch

Tara Keyser; Frederick Smith

2009-01-01

Two determinants of crown fire hazard are canopy bulk density (CBD) and canopy base height (CBH). The Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS) is a model that predicts CBD and CBH. Currently, FFE-FVS accounts for neither geographic variation in tree allometries nor the nonuniform distribution of crown mass when one is estimating CBH and CBD...

The potential for LiDAR technology to map fire fuel hazard over large areas of Australian forest.

PubMed

Price, Owen F; Gordon, Christopher E

2016-10-01

Fuel load is a primary determinant of fire spread in Australian forests. In east Australian forests, litter and canopy fuel loads and hence fire hazard are thought to be highest at and beyond steady-state fuel loads 15-20 years post-fire. Current methods used to predict fuel loads often rely on course-scale vegetation maps and simple time-since-fire relationships which mask fine-scale processes influencing fuel loads. Here we use Light Detecting and Remote Sensing technology (LiDAR) and field surveys to quantify post-fire mid-story and crown canopy fuel accumulation and fire hazard in Dry Sclerophyll Forests of the Sydney Basin (Australia) at fine spatial-scales (20 × 20 m cell resolution). Fuel cover was quantified in three strata important for crown fire propagation (0.5-4 m, 4-15 m, >15 m) over a 144 km(2) area subject to varying fire fuel ages. Our results show that 1) LiDAR provided a precise measurement of fuel cover in each strata and a less precise but still useful predictor of surface fuels, 2) cover varied greatly within a mapped vegetation class of the same fuel age, particularly for elevated fuel, 3) time-since-fire was a poor predictor of fuel cover and crown fire hazard because fuel loads important for crown fire propagation were variable over a range of fire fuel ages between 2 and 38 years post-fire, and 4) fuel loads and fire hazard can be high in the years immediately following fire. Our results show the benefits of spatially and temporally specific in situ fuel sampling methods such as LiDAR, and are widely applicable for fire management actions which aim to decrease human and environmental losses due to wildfire. Copyright © 2016 Elsevier Ltd. All rights reserved.

An algorithm of the wildfire classification by its acoustic emission spectrum using Wireless Sensor Networks

NASA Astrophysics Data System (ADS)

Khamukhin, A. A.; Demin, A. Y.; Sonkin, D. M.; Bertoldo, S.; Perona, G.; Kretova, V.

2017-01-01

Crown fires are extremely dangerous as the speed of their distribution is dozen times higher compared to surface fires. Therefore, it is important to classify the fire type as early as possible. A method for forest fires classification exploits their computed acoustic emission spectrum compared with a set of samples of the typical fire acoustic emission spectrum stored in the database. This method implies acquisition acoustic data using Wireless Sensors Networks (WSNs) and their analysis in a central processing and a control center. The paper deals with an algorithm which can be directly implemented on a sensor network node that will allow reducing considerably the network traffic and increasing its efficiency. It is hereby suggested to use the sum of the squares ratio, with regard to amplitudes of low and high frequencies of the wildfire acoustic emission spectrum, as the indicator of a forest fire type. It is shown that the value of the crown fires indicator is several times higher than that of the surface ones. This allows classifying the fire types (crown, surface) in a short time interval and transmitting a fire type indicator code alongside with an alarm signal through the network.

Mapping forest canopy fuels in Yellowstone National Park using lidar and hyperspectral data

NASA Astrophysics Data System (ADS)

Halligan, Kerry Quinn

The severity and size of wildland fires in the forested western U.S have increased in recent years despite improvements in fire suppression efficiency. This, along with increased density of homes in the wildland-urban interface, has resulted in high costs for fire management and increased risks to human health, safety and property. Crown fires, in comparison to surface fires, pose an especially high risk due to their intensity and high rate of spread. Crown fire models require a range of quantitative fuel parameters which can be difficult and costly to obtain, but advances in lidar and hyperspectral sensor technologies hold promise for delivering these inputs. Further research is needed, however, to assess the strengths and limitations of these technologies and the most appropriate analysis methodologies for estimating crown fuel parameters from these data. This dissertation focuses on retrieving critical crown fuel parameters, including canopy height, canopy bulk density and proportion of dead canopy fuel, from airborne lidar and hyperspectral data. Remote sensing data were used in conjunction with detailed field data on forest parameters and surface reflectance measurements. A new method was developed for retrieving Digital Surface Model (DSM) and Digital Canopy Models (DCM) from first return lidar data. Validation data on individual tree heights demonstrated the high accuracy (r2 0.95) of the DCMs developed via this new algorithm. Lidar-derived DCMs were used to estimate critical crown fire parameters including available canopy fuel, canopy height and canopy bulk density with linear regression model r2 values ranging from 0.75 to 0.85. Hyperspectral data were used in conjunction with Spectral Mixture Analysis (SMA) to assess fuel quality in the form of live versus dead canopy proportions. Severity and stage of insect-caused forest mortality were estimated using the fractional abundance of green vegetation, non-photosynthetic vegetation and shade obtained from SMA. Proportion of insect attack was estimated with a linear model producing an r2 of 0.6 using SMA and bark endmembers from image and reference libraries. Fraction of red attack, with a possible link to increased crown fire risk, was estimated with an r2 of 0.45.

Fire treatment effects on vegetation structure, fuels, and potential fire severity in western U.S. forests

USGS Publications Warehouse

Stephens, S.L.; Moghaddas, J.J.; Edminster, C.; Fiedler, C.E.; Haase, S.; Harrington, M.; Keeley, J.E.; Knapp, E.E.; Mciver, J.D.; Metlen, K.; Skinner, C.N.; Youngblood, A.

2009-01-01

Abstract. Forest structure and species composition in many western U.S. coniferous forests have been altered through fire exclusion, past and ongoing harvesting practices, and livestock grazing over the 20th century. The effects of these activities have been most pronounced in seasonally dry, low and mid-elevation coniferous forests that once experienced frequent, low to moderate intensity, fire regimes. In this paper, we report the effects of Fire and Fire Surrogate (FFS) forest stand treatments on fuel load profiles, potential fire behavior, and fire severity under three weather scenarios from six western U.S. FFS sites. This replicated, multisite experiment provides a framework for drawing broad generalizations about the effectiveness of prescribed fire and mechanical treatments on surface fuel loads, forest structure, and potential fire severity. Mechanical treatments without fire resulted in combined 1-, 10-, and 100-hour surface fuel loads that were significantly greater than controls at three of five FFS sites. Canopy cover was significantly lower than controls at three of five FFS sites with mechanical-only treatments and at all five FFS sites with the mechanical plus burning treatment; fire-only treatments reduced canopy cover at only one site. For the combined treatment of mechanical plus fire, all five FFS sites with this treatment had a substantially lower likelihood of passive crown fire as indicated by the very high torching indices. FFS sites that experienced significant increases in 1-, 10-, and 100-hour combined surface fuel loads utilized harvest systems that left all activity fuels within experimental units. When mechanical treatments were followed by prescribed burning or pile burning, they were the most effective treatment for reducing crown fire potential and predicted tree mortality because of low surface fuel loads and increased vertical and horizontal canopy separation. Results indicate that mechanical plus fire, fire-only, and mechanical-only treatments using whole-tree harvest systems were all effective at reducing potential fire severity under severe fire weather conditions. Retaining the largest trees within stands also increased fire resistance. ?? 2009 by the Ecological Society of America.

Evaluation of sampling strategies to estimate crown biomass

Treesearch

Krishna P Poudel; Hailemariam Temesgen; Andrew N Gray

2015-01-01

Depending on tree and site characteristics crown biomass accounts for a significant portion of the total aboveground biomass in the tree. Crown biomass estimation is useful for different purposes including evaluating the economic feasibility of crown utilization for energy production or forest products, fuel load assessments and fire management strategies, and wildfire...

Growth Reponse of Loblolly Pine to Intermediate Treatment of Fire, Herbicide, and Fertilizer: Preliminary Results

Treesearch

L.M. Marino; B.P. Oswald; K.W. Farrish; H.M. Williams; Daniel R. Unger

2002-01-01

Crown area is an important factor in determining stem development. This study examined the changes in stem diameter per unit area of crown due to treatment with fire, herbicide, fertilizer, and tree-thinning practice. The experimental sites were mid-rotation loblolly pine (Pinus taeda) plantations that were thinned one year before treatment. Site 1...

Effects of bark beetle attack on canopy fuel flammability and crown fire potential in lodgepole pine and Engelmann spruce forests

Treesearch

Wesley G. Page; Martin E. Alexander; Michael J. Jenkins

2015-01-01

Large wildland fires in conifer forests typically involve some degree of crowning, with their initiation and propagation dependent upon several characteristics of the canopy fuels. Recent outbreaks of mountain pine beetle (Dendroctonus ponderosae Hopkins) in lodgepole pine (Pinus contorta Dougl. var. latifolia E ngelm.) forests and spruce beetle (Dendroctonus...

Simulations of Forest Fires by the Cellular Automata Model "ABBAMPAU"

NASA Astrophysics Data System (ADS)

di Gregorio, S.; Bendicenti, E.

2003-04-01

Forest fires represent a serious environmental problem, whose negative impact is becoming day by day more worrisome. Forest fires are very complex phenomena; that need an interdisciplinary approach. The adopted method to modelling involves the definition of local rules, from which the global behaviour of the system can emerge. The paradigm of Cellular Automata was applied and the model ABBAMPAU was projected to simulate the evolution of forest fires. Cellular Automata features (parallelism and a-centrism) seem to match the system "forest fire"; the parameters, describing globally a forest fire, i.e. propagation rate, flame length and direction, fireline intensity, fire duration time et c. are mainly depending on some local characteristics i.e. vegetation type (live and dead fuel), relative humidity, fuel moisture, heat, territory morphology (altitude, slope), et c.. The only global characteristic is given by wind velocity and direction, but wind velocity and direction is locally altered according to the morphology; therefore wind has also to be considered at local level. ABBAMPAU accounts for the following aspects of the phenomenon: effects of combustion in surface and crown fire inside the cell, crown fire triggering off; surface and crown fire spread, determination of the local wind rate and direction. A validation of ABBAMPAU was tested on a real case of forest fire, in the territory of Villaputzu, Sardinia island, August 22nd, 1998. First simulations account for the main characteristics of the phenomenon and agree with the observations. The results show that the model could be applied for the forest fire preventions, the productions of risk scenarios and the evaluation of the forest fire environmental impact.

Wildland Fire Forecasting: Predicting Wildfire Behavior, Growth, and Feedbacks on Weather

NASA Astrophysics Data System (ADS)

Coen, J. L.

2005-12-01

Recent developments in wildland fire research models have represented more complex of fire behavior. The cost has been to increase the computational requirements. When operational constraints are included, such as the need to produce such forecasts faster than real time, the challenge becomes a balance of how much complexity (with corresponding gains in realism) and accuracy can be achieved in producing the quantities of interest while meeting the specified operational constraints. Current field tools are calculator or Palm-Pilot based algorithms such as BEHAVE and BEHAVE Plus that produce timely estimates of instantaneous fire spread rates, flame length, and fire intensity at a point using readily estimated inputs of fuel model, terrain slope, and atmospheric wind speed at a point. At the cost of requiring a PC and slower calculation, FARSITE represents two-dimensional fire spread and adds capabilities including a parameterized representation of crown fire ignition, This work describes how a coupled atmosphere-fire model previously used as a research tool has been adapted for production of real-time forecasts of fire growth and its interactions with weather over a domain focusing on Colorado during summer 2004. The coupled atmosphere-wildland fire-environment (CAWFE) model composed of a 3-dimensional atmospheric prediction model that has been two-way coupled with an empirical fire spread model. The models are connected in that atmospheric conditions (and fuel conditions influenced by the atmosphere) affect the rate and direction of fire propagation, which releases sensible and latent heat (i.e. thermal and water vapor fluxes) to the atmosphere that in turn alter the winds and atmospheric structure around the fire. Thus, it can represent time and spatially-varying weather and the fire feedbacks on the atmospheric which are at the heart of sudden changes in fire behavior and examples of extreme fire behavior such as blow ups, which are now not predictable with current tools. Thus, although this work shows that is it possible to perform more detailed simulations in real time, fire behavior forecasting remains a challenging problem. This is due to challenges in weather prediction, particularly at fine spatial and temporal scales considered "nowcasting" (0-6 hrs), uncertainties in fire behavior even with known meteorological conditions, limitations in quantitative datasets on fuel properties such as fuel loading, and verification. This work describes efforts to advance these capabilities with input from remote sensing data on fuel characteristics and dynamic steering and object-based verification with remotely sensed fire perimeters.

Fuel buildup and potential fire behavior after stand-replacing fires, logging fire-killed trees and herbicide shrub removal in Sierra Nevada forests

USGS Publications Warehouse

McGinnis, Thomas W.; Keeley, Jon E.; Stephens, Scott L.; Roller, Gary B.

2010-01-01

Typically, after large stand-replacing fires in mid-elevation Sierra Nevada forests, dense shrub fields occupy sites formerly occupied by mature conifers, until eventually conifers overtop and shade out shrubs. Attempting to reduce fuel loads and expedite forest regeneration in these areas, the USDA Forest Service often disrupts this cycle by the logging of fire-killed trees, replanting of conifers and killing of shrubs. We measured the effects of these treatments on live and dead fuel loads and alien species and modeled potential fire behavior and fire effects on regenerating forests. Sampling occurred in untreated, logged and herbicide-treated stands throughout the Sierra Nevada in four large fire areas 4–21 years after stand-replacing fires. Logging fire-killed trees significantly increased total available dead fuel loads in the short term but did not affect shrub cover, grass and forb cover, alien species cover or alien species richness. Despite the greater available dead fuel loads, fire behavior was not modeled to be different between logged and untreated stands, due to abundant shrub fuels in both logged and untreated stands. In contrast, the herbicide treatment directed at shrubs resulted in extremely low shrub cover, significantly greater alien species richness and significantly greater alien grass and forb cover. Grass and forb cover was strongly correlated with solar radiation on the ground, which may be the primary reason that grass and forb cover was higher in herbicide treated stands with low shrub and tree cover. Repeat burning exacerbated the alien grass problem in some stands. Although modeled surface fire flame lengths and rates of spread were found to be greater in stands dominated by shrubs, compared to low shrub cover conifer plantations, surface fire would still be intense enough to kill most trees, given their small size and low crown heights in the first two decades after planting.

Broadleaf deciduous forest counterbalanced the direct effect of climate on Holocene fire regime in hemiboreal/boreal region (NE Europe)

NASA Astrophysics Data System (ADS)

Feurdean, Angelica; Veski, Siim; Florescu, Gabriela; Vannière, Boris; Pfeiffer, Mirjam; O'Hara, Robert B.; Stivrins, Normunds; Amon, Leeli; Heinsalu, Atko; Vassiljev, Jüri; Hickler, Thomas

2017-08-01

Disturbances by fire are essential for the functioning of boreal/hemiboreal forests, but knowledge of long-term fire regime dynamics is limited. We analysed macrocharcoal morphologies and pollen of a sediment record from Lake Lielais Svētiņu (eastern Latvia), and in conjunction with fire traits analysis present the first record of Holocene variability in fire regime, fuel sources and fire types in boreal forests of the Baltic region. We found a phase of moderate to high fire activity during the cool and moist early (mean fire return interval; mFRI of ∼280 years; 11,700-7500 cal yr BP) and the late (mFRI of ∼190 years; 4500-0 cal yr BP) Holocene and low fire activity (mFRI of ∼630 years) during the Holocene Thermal Optimum (7500-4500 cal yr BP). Charcoal morphotypes and the pollen record show the predominance of frequent surface fires, occasionally transitioning to the crown during Pinus sylvestris-Betula boreal forests and less frequent surface fires during the dominance of temperate deciduous forests. In contrast to the prevailing opinion that fires in boreal forests are mostly low to moderate severity surface fires, we found evidence for common occurrence of stand-replacing crown fires in Picea abies canopy. Our results highlight that charcoal morphotypes analysis allows for distinguishing the fuel types and surface from crown fires, therefore significantly advancing our interpretation of fire regime. Future warmer temperatures and increase in the frequency of dry spells and abundant biomass accumulation can enhance the fire risk on the one hand, but will probably promote the expansion of broadleaf deciduous forests to higher latitudes, on the other hand. By highlighting the capability of broadleaf deciduous forests to act as fire-suppressing landscape elements, our results suggest that fire activity may not increase in the Baltic area under future climate change.

Numerical simulation of crown fire hazard following bark beetle-caused mortality in lodgepole pine forests

Treesearch

Chad Hoffman; Russell Parsons; Penny Morgan; Ruddy Mell

2010-01-01

The purpose of this study is to investigate how varying amounts of MPB-induced tree mortality affects the amount of crown fuels consumed and the fire intensity across a range of lodgepole pine stands of different tree density and spatial arrangements during the early stages of a bark beetle outbreak. Unlike past studies which have relied on semi-empirical or empirical...

Historical, observed, and modeled wildfire severity in montane forests of the Colorado Front Range.

PubMed

Sherriff, Rosemary L; Platt, Rutherford V; Veblen, Thomas T; Schoennagel, Tania L; Gartner, Meredith H

2014-01-01

Large recent fires in the western U.S. have contributed to a perception that fire exclusion has caused an unprecedented occurrence of uncharacteristically severe fires, particularly in lower elevation dry pine forests. In the absence of long-term fire severity records, it is unknown how short-term trends compare to fire severity prior to 20th century fire exclusion. This study compares historical (i.e. pre-1920) fire severity with observed modern fire severity and modeled potential fire behavior across 564,413 ha of montane forests of the Colorado Front Range. We used forest structure and tree-ring fire history to characterize fire severity at 232 sites and then modeled historical fire-severity across the entire study area using biophysical variables. Eighteen (7.8%) sites were characterized by low-severity fires and 214 (92.2%) by mixed-severity fires (i.e. including moderate- or high-severity fires). Difference in area of historical versus observed low-severity fire within nine recent (post-1999) large fire perimeters was greatest in lower montane forests. Only 16% of the study area recorded a shift from historical low severity to a higher potential for crown fire today. An historical fire regime of more frequent and low-severity fires at low elevations (<2260 m) supports a convergence of management goals of ecological restoration and fire hazard mitigation in those habitats. In contrast, at higher elevations mixed-severity fires were predominant historically and continue to be so today. Thinning treatments at higher elevations of the montane zone will not return the fire regime to an historic low-severity regime, and are of questionable effectiveness in preventing severe wildfires. Based on present-day fuels, predicted fire behavior under extreme fire weather continues to indicate a mixed-severity fire regime throughout most of the montane forest zone. Recent large wildfires in the Front Range are not fundamentally different from similar events that occurred historically under extreme weather conditions.

Historical, Observed, and Modeled Wildfire Severity in Montane Forests of the Colorado Front Range

PubMed Central

Sherriff, Rosemary L.; Platt, Rutherford V.; Veblen, Thomas T.; Schoennagel, Tania L.; Gartner, Meredith H.

2014-01-01

Large recent fires in the western U.S. have contributed to a perception that fire exclusion has caused an unprecedented occurrence of uncharacteristically severe fires, particularly in lower elevation dry pine forests. In the absence of long-term fire severity records, it is unknown how short-term trends compare to fire severity prior to 20th century fire exclusion. This study compares historical (i.e. pre-1920) fire severity with observed modern fire severity and modeled potential fire behavior across 564,413 ha of montane forests of the Colorado Front Range. We used forest structure and tree-ring fire history to characterize fire severity at 232 sites and then modeled historical fire-severity across the entire study area using biophysical variables. Eighteen (7.8%) sites were characterized by low-severity fires and 214 (92.2%) by mixed-severity fires (i.e. including moderate- or high-severity fires). Difference in area of historical versus observed low-severity fire within nine recent (post-1999) large fire perimeters was greatest in lower montane forests. Only 16% of the study area recorded a shift from historical low severity to a higher potential for crown fire today. An historical fire regime of more frequent and low-severity fires at low elevations (<2260 m) supports a convergence of management goals of ecological restoration and fire hazard mitigation in those habitats. In contrast, at higher elevations mixed-severity fires were predominant historically and continue to be so today. Thinning treatments at higher elevations of the montane zone will not return the fire regime to an historic low-severity regime, and are of questionable effectiveness in preventing severe wildfires. Based on present-day fuels, predicted fire behavior under extreme fire weather continues to indicate a mixed-severity fire regime throughout most of the montane forest zone. Recent large wildfires in the Front Range are not fundamentally different from similar events that occurred historically under extreme weather conditions. PMID:25251103

Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds

PubMed Central

Vaughn, Nicholas R.; Asner, Gregory P.; Smit, Izak P. J.; Riddel, Edward S.

2015-01-01

Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50–450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques. PMID:26660502

Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

PubMed

Vaughn, Nicholas R; Asner, Gregory P; Smit, Izak P J; Riddel, Edward S

2015-01-01

Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

Effects of prescribed fire on wintering, bark-foraging birds in northern Arizona

Treesearch

Theresa L. Pope

2006-01-01

Forest management practices of the past century have led to an increase in unnatural and destructive crown fires in ponderosa pine (Pinus ponderosa) forests of the southwest. To combat large fires, forest managers are attempting to simulate past fire regimes of low-intensity surface fires using prescribed fire. While there have been many studies...

Variation in fire regimes of the Rocky Mountains: implications for avian communities and fire management

Treesearch

Victoria A. Saab; Hugh D. W. Powell; Natasha B. Kotliar; Karen R. Newlon

2005-01-01

Information about avian responses to fire in the U.S. Rocky Mountains is based solely on studies of crown fires. However, fire management in this region is based primarily on studies of low-elevation ponderosa pine (Pinus ponderosa) forests maintained largely by frequent understory fires. In contrast to both of these trends, most Rocky Mountain...

Seedbed Requirements For Regenerating Table Mountain Pine With Prescribed Fire

Treesearch

Thomas A. Waldrop; Helen H. Mohr; Patrick H. Brose; Richard B. Baker

1999-01-01

High-intensity, stand-replacement fires have been recommnded to regenerate stands of Table Mountain pine (Pinus pungens Lamb.) because its seeds require mineral soil to germinate and seedlings are intolerant of shade. Early prescribed fire efforts resulted in poor regeneration success where crown fires created seedbeds with abundant insolation....

Estimating canopy bulk density and canopy base height for interior western US conifer stands

Treesearch

Seth A. Ex; Frederick W. Smith; Tara L. Keyser; Stephanie A. Rebain

2016-01-01

Crown fire hazard is often quantified using effective canopy bulk density (CBD) and canopy base height (CBH). When CBD and CBH are estimated using nonlocal crown fuel biomass allometries and uniform crown fuel distribution assumptions, as is common practice, values may differ from estimates made using local allometries and nonuniform...

Estimating forest canopy bulk density using six indirect methods

Treesearch

Robert E. Keane; Elizabeth D. Reinhardt; Joe Scott; Kathy Gray; James Reardon

2005-01-01

Canopy bulk density (CBD) is an important crown characteristic needed to predict crown fire spread, yet it is difficult to measure in the field. Presented here is a comprehensive research effort to evaluate six indirect sampling techniques for estimating CBD. As reference data, detailed crown fuel biomass measurements were taken on each tree within fixed-area plots...

Range expansion of invasive shrubs: implication for crown fire risk in forestlands of the southern USA.

PubMed

Wang, Hsiao-Hsuan; Wonkka, Carissa L; Grant, William E; Rogers, William E

2016-01-01

Non-native plant invasions and changing management activities have dramatically altered the structure and composition of forests worldwide. Invasive shrubs and fire suppression have led to increased densification and biomass accumulation in forest ecosystems of the southeastern USA. Notably, Chinese and European privets are rapid growing, shade-tolerant shrubs which number among the most aggressive invasive species in these forests. Privet encroachment has caused losses of native diversity, alteration of ecosystem processes and changes in community structure. The latter has become manifest through decreases in fine herbaceous fuels concurrent with increases in coarse woody fuels in forest understoreys. These alterations in fuel structure will potentially lead to less frequent, but more severe forest fires, which threaten important forest resources during extreme weather conditions. Drawing on extensive data sets compiled by the US Forest Service, we integrated statistical forecasting and analytical techniques within a spatially explicit, agent-based, simulation framework to predict potential range expansion of Chinese and European privet (Ligustrum sinenseandL. vulgare) and the associated increase in crown fire risk over the next two decades in forestlands of Mississippi and Alabama. Our results indicate that probability of invasion is positively associated with elevation, adjacency (within 300 m) to water bodies, mean daily maximum temperature, site productivity and private land ownership, and is negatively associated with slope, stand age, artificial regeneration, distance to the nearest road and fire disturbance. Our projections suggest the total area invaded will increase from 1.36 to ≈31.39% of all forestlands in Mississippi and Alabama (≈7 million hectares) and the annual frequency of crown fires in these forestlands will approximately double within the next two decades. Such time series projections of annual range expansions and crown fire frequency should provide land managers and restoration practitioners with an invasion chronology upon which to base proactive management plans. Published by Oxford University Press on behalf of the Annals of Botany Company.

Range expansion of invasive shrubs: implication for crown fire risk in forestlands of the southern USA

PubMed Central

Wang, Hsiao-Hsuan; Wonkka, Carissa L.; Grant, William E.; Rogers, William E.

2016-01-01

Non-native plant invasions and changing management activities have dramatically altered the structure and composition of forests worldwide. Invasive shrubs and fire suppression have led to increased densification and biomass accumulation in forest ecosystems of the southeastern USA. Notably, Chinese and European privets are rapid growing, shade-tolerant shrubs which number among the most aggressive invasive species in these forests. Privet encroachment has caused losses of native diversity, alteration of ecosystem processes and changes in community structure. The latter has become manifest through decreases in fine herbaceous fuels concurrent with increases in coarse woody fuels in forest understoreys. These alterations in fuel structure will potentially lead to less frequent, but more severe forest fires, which threaten important forest resources during extreme weather conditions. Drawing on extensive data sets compiled by the US Forest Service, we integrated statistical forecasting and analytical techniques within a spatially explicit, agent-based, simulation framework to predict potential range expansion of Chinese and European privet (Ligustrum sinense and L. vulgare) and the associated increase in crown fire risk over the next two decades in forestlands of Mississippi and Alabama. Our results indicate that probability of invasion is positively associated with elevation, adjacency (within 300 m) to water bodies, mean daily maximum temperature, site productivity and private land ownership, and is negatively associated with slope, stand age, artificial regeneration, distance to the nearest road and fire disturbance. Our projections suggest the total area invaded will increase from 1.36 to ≈31.39% of all forestlands in Mississippi and Alabama (≈7 million hectares) and the annual frequency of crown fires in these forestlands will approximately double within the next two decades. Such time series projections of annual range expansions and crown fire frequency should provide land managers and restoration practitioners with an invasion chronology upon which to base proactive management plans. PMID:26903488

Vegetation and soil effects from prescribed, wild, and combined fire events along a ponderosa pine and grassland mosaic

Treesearch

Theresa Jain; Molly Juillerat; Jonathan Sandquist; Mike Ford; Brad Sauer; Robert Mitchell; Scott McAvoy; Justin Hanley; Jon David

2007-01-01

We describe the efficacy of prescribed fires after two wildfires burned through and around these fires located in eastern Montana within the Missouri River Breaks. The objectives of the prescribed fires were to decrease tree density and favor increased herbaceous cover, thus decreasing the potential for crown fire. Our objective was to evaluate post-fire tree density,...

Correlations between tree crown condition and shade tolerance, crown form, and light availability

Treesearch

KaDonna C. Randolph

2007-01-01

Individual tree crown condition is the result of a combination of many factors including genetic traits, growing site characteristics, and past and present external stresses (e.g., drought, insect outbreaks, fire, etc.). Shade tolerance and the extent to which terminal buds control the length and orientation of lateral branches (epinastic control) are the two primary...

Estimation of crown cover in interior ponderosa pine stands: Effects of thinning and prescribed fire

Treesearch

Nicholas Vaughn; Martin W. Ritchie

2005-01-01

We evaluated the relationship between crown cover measured with a vertical sight tube and stand basal area per acre in treated (thinned, burned, and thinned and burned) and untreated interior ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in northeastern California. Crown cover was significantly related to basal area at the plot level and...

Mathematical modeling of forest fire initiation in three dimensional setting

Treesearch

Valeriy Perminov

2007-01-01

In this study, the assignment and theoretical investigations of the problems of forest fire initiation were carried out, including development of a mathematical model for description of heat and mass transfer processes in overterrestrial layer of atmosphere at crown forest fire initiation, taking into account their mutual influence. Mathematical model of forest fire...

Increased fire frequency promotes stronger spatial genetic structure and natural selection at regional and local scales in Pinus halepensis Mill

PubMed Central

González-Martínez, Santiago C.; Navascués, Miguel; Burgarella, Concetta; Mosca, Elena; Lorenzo, Zaida; Zabal-Aguirre, Mario; Vendramin, Giovanni G.; Verdú, Miguel; Pausas, Juli G.

2017-01-01

Background and Aims The recurrence of wildfires is predicted to increase due to global climate change, resulting in severe impacts on biodiversity and ecosystem functioning. Recurrent fires can drive plant adaptation and reduce genetic diversity; however, the underlying population genetic processes have not been studied in detail. In this study, the neutral and adaptive evolutionary effects of contrasting fire regimes were examined in the keystone tree species Pinus halepensis Mill. (Aleppo pine), a fire-adapted conifer. The genetic diversity, demographic history and spatial genetic structure were assessed at local (within-population) and regional scales for populations exposed to different crown fire frequencies. Methods Eight natural P. halepensis stands were sampled in the east of the Iberian Peninsula, five of them in a region exposed to frequent crown fires (HiFi) and three of them in an adjacent region with a low frequency of crown fires (LoFi). Samples were genotyped at nine neutral simple sequence repeats (SSRs) and at 251 single nucleotide polymorphisms (SNPs) from coding regions, some of them potentially important for fire adaptation. Key Results Fire regime had no effects on genetic diversity or demographic history. Three high-differentiation outlier SNPs were identified between HiFi and LoFi stands, suggesting fire-related selection at the regional scale. At the local scale, fine-scale spatial genetic structure (SGS) was overall weak as expected for a wind-pollinated and wind-dispersed tree species. HiFi stands displayed a stronger SGS than LoFi stands at SNPs, which probably reflected the simultaneous post-fire recruitment of co-dispersed related seeds. SNPs with exceptionally strong SGS, a proxy for microenvironmental selection, were only reliably identified under the HiFi regime. Conclusions An increasing fire frequency as predicted due to global change can promote increased SGS with stronger family structures and alter natural selection in P. halepensis and in plants with similar life history traits. PMID:28159988

Grizzly Gulch Fire, South Dakota

NASA Technical Reports Server (NTRS)

2002-01-01

Burning next door to the South Dakota towns of Deadwood and Lead, the Grizzly Gulch fire forced the evacuation of many residents in the first week of July, 2002. In addition, smoke closed many of the roads in the area. At the time the fire's behavior was extreme, with 'torching, spotting, and running.' In other words, the fire was primarily burning along the ground, with entire trees occasionally erupting into flame (torching). At the same time, burning embers were being thrown ahead of the fire (spotting). In some areas the fire was spreading from the crown of one tree to another (running). (This glossary of fire terms has a good list of definitions) The above image shows the fire on the morning of July 1, 2002. Actively burning areas, concentrated on the east (right) side of the fire, are colored red and orange. Dark red areas indicate burn scars, while forest and other vegetation appears green. The exposed rock of the Homestake gold mine, now the National Underground Science Laboratory, is pinkish-brown. The total extent of the fire is oulined in yellow. The image was acquired by the Enhanced Thematic Mapper plus (ETM+) aboard the Landsat 7 satellite. More news about current wildfires in the United States is available from the National Fire Information Center. Image provided by the USGS EROS Data Center Satellite Systems Branch.

Influence of herbivory on regrowth of riparian shrubs following a wildland fire

Treesearch

Kathleen A. Dwire; Sandra E. Ryan; Laura J. Shirley; Danna Lytjen; Nick Otting; Mark K. Dixon

2006-01-01

Streamside vegetation frequently regenerates faster than upland vegetation following wildland fire and contributes to the recovery of riparian and stream ecosystems. Limited data are available, however, on the post-fire growth of riparian species and the influence of herbivory on regeneration. To determine post-fire regrowth of riparian vegetation, height, crown area,...

Fuels planning: science synthesis and integration; forest structure and fire hazard fact sheet 04: role of silviculture in fuel treatments

Treesearch

Rocky Mountain Research Station USDA Forest Service

2004-01-01

The principal goals of fuel treatments are to reduce fireline intensities, reduce the potential for crown fires, improve opportunities for successful fire suppression, and improve forest resilience to forest fires. This fact sheet discusses thinning, and surface fuel treatments, as well as challenges associated with those treatments.

Two keys for appraising forest fire fuels.

Treesearch

George R. Fahnestock

1970-01-01

This is an attempt to characterize forest fire fuels in a new way. The immediate purpose is to provide means for recognizing and tentatively evaluating, in the field, the fire spread potential and the crowning potential of fuels on the basis of readily observed characteristics without need for prior technical knowledge of vegetation or experience with fire. The medium...

Varied ecosystems need different fire protection

USGS Publications Warehouse

Gutsell, Sheri L.; Johnson, Edward A.; Miyanishi, Kiyoko; Keeley, Jon E.; Dickinson, Matthew; Bridge, Simon R. J.

2001-01-01

Covington states in his Commentary1 that the open ponderosa pine forests of the western United States are "in widespread collapse" because fire suppression by humans has eliminated the low-intensity surface fire regime that maintained the open, park-like structure of these forests. He fears this will lead to an "unprecedented" crown fire regime that will eliminate forests.

Are Crown Fires Necessary For Table Mountain Pine?

Treesearch

Thomas A. Waldrop; Patrick H. Brose; Nicole Turrill Welch; Helen H. Mohr; Ellen A. Gray; Frank H. Tainter; Lisa E. Ellis

2003-01-01

Ridgetop pine communities of the southern Appalachian Mountains have historically been maintained by lightning- and human-caused fires. Because of fire supression for several decades, these stands are entering later seral stages. Such stands typically have an overstory of Table Mountain Pine (Pinus pungens) that is being replaced by shade tolerant...

Optimal Seedbed Requirements For Regenerating Table Mountain Pine

Treesearch

Helen H. Mohr; Thomas A. Waldrop; Victor B. Shelburne

2002-01-01

High-intensity, stand replacement fires have been recommended to regenerate stands of Table Mountain pine (Pinus pungens Lamb.) because its seeds require mineral soil to germinate and seedlings are intolerant of shade. Recent prescribed fires have resulted in poor regeneration, even though crown fires created seedbeds with abundant insolation and...

Influence of surface treatment on the in-vitro fracture resistance of zirconia-based all-ceramic anterior crowns.

PubMed

Schmitter, M; Lotze, G; Bömicke, W; Rues, S

2015-12-01

The purpose of this study was to assess the effect of surface treatment on the fracture resistance of zirconia-based all-ceramic anterior crowns. Sixty-four zirconia-based all-ceramic anterior crowns, veneered by use of a press-on technique, were produced. For 48 crowns intraoral adjustment was simulated (A-group), 16 crowns remained unadjusted (WA-group). The adjusted area was then treated in three ways: 1. no further surface treatment; 2. polishing, with irrigation, using polishers interspersed with diamond grit for ceramics; and 3. polishing and glaze firing. Half of the specimens were loaded until fracture in an universal testing device without artificial ageing; the other crowns underwent thermocycling and chewing simulation before ultimate-load testing. Explorative statistical analysis was performed by use of non-parametric and parametric tests. In addition, fracture-strength tests according to ISO 6872 were performed for veneer ceramic subjected to the different surface treatments. Finite element analysis was also conducted for the crowns, and surface roughness was measured. Crowns in the A-group were more sensitive to aging than crowns in the WA-group (p=0.038). Although both polishing and glaze firing slightly improved the fracture resistance of the specimens, the fracture resistance in the WA-group (initial fracture resistance (IFR): 652.0 ± 107.7N, remaining fracture resistance after aging (RFR): 560.6 ± 233.3N) was higher than the fracture resistance in the A-group (polished: IFR: 477.9 ± 108.8N, RFR: 386.0 ± 218.5N; glaze firing: IFR: 535.5 ± 128.0N, RFR: 388.6 ± 202.2N). Surface roughness without adjustment was Ra=0.1 μm; for adjustment but without further treatment it was Ra=1.4 μm; for adjustment and polishing it was Ra=0.3 μm; and for adjustment, polishing, and glazing it was Ra=0.6 μm. Stress distributions obtained by finite element analysis in combination with fracture strength tests showed that fractures most probably originated from the occlusal surface. To improve fracture resistance and reduce the incidence of failure, extensive occlusal adjustment of veneered anterior zirconia restorations should be avoided. Neither polishing nor glazing could restore the fracture resistance to the level maintained with unadjusted crowns. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Estimating ladder fuels: a new approach combining field photography with LiDAR

Treesearch

Heather Kramer; Brandon Collins; Frank Lake; Marek Jakubowski; Scott Stephens; Maggi Kelly

2016-01-01

Forests historically associated with frequent fire have changed dramatically due to fire suppression and past harvesting over the last century. The buildup of ladder fuels, which carry fire from the surface of the forest floor to tree crowns, is one of the critical changes, and it has contributed to uncharacteristically large and severe fires. The abundance of ladder...

Management of fire regime, fuels, and fire effects in southern California chaparral: lessons from the past and thoughts for the future

Treesearch

Susan G. Conard; David R. Weise

1998-01-01

Chaparral is an intermediate fire-return interval (FRI) system, which typically bums with high-intensity crown fires. Although it covers only perhaps 10% of the state of California, and smaller areas in neighboring states, its importance in terms of fire management is disproportionately large, primarily because it occurs in the wildland-urban interface through much of...

Vegetation and topographical correlates of fire severity from two fires in the Klamath-Siskiyou region of Oregon and California

Treesearch

John D. Alexander; Nathaniel E. Seavy; C Ralph; Bill Hogoboom

2006-01-01

We used vegetation data collected in areas before they were burned by the 2500 ha Quartz fire in southern Oregon and the 50 600 ha Big Bar complex in northern California to evaluate the ability of vegetation and topographic characteristics to predict patterns of fire severity. Fire severity was characterized as high, moderate, or low based on crown scorch and...

Fall rates of prescribed fire-killed ponderosa pine. Forest Service research paper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrington, M.G.

1996-05-01

Fall rates of prescribed fire-killed ponderosa pine were evaluated relative to tree and fire damage characteristics. High crown scorch and short survival time after fire injury were factors leading to a high probability of early tree fall. The role of chemical defense mechanisms is discussed. Results apply to prescribed-fire injured, second-growth ponderosa pine less than 16 inches diameter at breast height.

Evaluation of the composite burn index for assessing fire severity in Alaskan black spruce forests

Treesearch

Eric S. Kasischke; Merritt R. Turetsky; Roger D. Ottmar; Nancy H.F. French; Elizabeth E. Hoy; Evan S. Kane

2008-01-01

We evaluated the utility of the composite burn index (CBI) for estimating fire severity in Alaskan black spruce forests by comparing data from 81 plots located in 2004 and 2005 fire events. We collected data to estimate the CBI and quantify crown damage, percentage of trees standing after the fire, depth of the organic layer remaining after the fire, depth of burning...

Fuel deposition rates of montane and subalpine conifers in the central Sierra Nevada, California, USA

USGS Publications Warehouse

van Wagtendonk, J.W.; Moore, P.E.

2010-01-01

Fire managers and researchers need information on fuel deposition rates to estimate future changes in fuel bed characteristics, determine when forests transition to another fire behavior fuel model, estimate future changes in fuel bed characteristics, and parameterize and validate ecosystem process models. This information is lacking for many ecosystems including the Sierra Nevada in California, USA. We investigated fuel deposition rates and stand characteristics of seven montane and four subalpine conifers in the Sierra Nevada. We collected foliage, miscellaneous bark and crown fragments, cones, and woody fuel classes from four replicate plots each in four stem diameter size classes for each species, for a total of 176 sampling sites. We used these data to develop predictive equations for each fuel class and diameter size class of each species based on stem and crown characteristics. There were consistent species and diameter class differences in the annual amount of foliage and fragments deposited. Foliage deposition rates ranged from just over 50 g m-2 year-1 in small diameter mountain hemlock stands to ???300 g m-2 year-1 for the three largest diameter classes of giant sequoia. The deposition rate for most woody fuel classes increased from the smallest diameter class stands to the largest diameter class stands. Woody fuel deposition rates varied among species as well. The rates for the smallest woody fuels ranged from 0.8 g m-2 year-1 for small diameter stands of Jeffrey pine to 126.9 g m-2 year-1 for very large diameter stands of mountain hemlock. Crown height and live crown ratio were the best predictors of fuel deposition rates for most fuel classes and species. Both characteristics reflect the amount of crown biomass including foliage and woody fuels. Relationships established in this study allow predictions of fuel loads to be made on a stand basis for each of these species under current and possible future conditions. These predictions can be used to estimate fuel treatment longevity, assist in determining fuel model transitions, and predict future changes in fuel bed characteristics.

Compartmentalization of pathogens in fire-injured trees

Treesearch

Kevin T. Smith

2013-01-01

Wildland fire is an episodic process that greatly influences the composition, structure, and developmental sequence of forests. Most news reports of wildland fire involves blazes fueled by slash, standing dead stems, and snags that reach into tree crowns and burn deeply into the forest floor, causing extensive tree mortality and the eventual replacement of the standing...

Plant functional traits in relation to fire in crown-fire ecosystems

USGS Publications Warehouse

Pausas, Juli G.; Bradstock, Ross A.; Keith, David A.; Keeley, Jon E.

2004-01-01

Disturbance is a dominant factor in many ecosystems, and the disturbance regime is likely to change over the next decades in response to land-use changes and global warming. We assume that predictions of vegetation dynamics can be made on the basis of a set of life-history traits that characterize the response of a species to disturbance. For crown-fire ecosystems, the main plant traits related to postfire persistence are the ability to resprout (persistence of individuals) and the ability to retain a persistent seed bank (persistence of populations). In this context, we asked (1) to what extent do different life-history traits co-occur with the ability to resprout and/or the ability to retain a persistent seed bank among differing ecosystems and (2) to what extent do combinations of fire-related traits (fire syndromes) change in a fire regime gradient? We explored these questions by reviewing the literature and analyzing databases compiled from different crown-fire ecosystems (mainly eastern Australia, California, and the Mediterranean basin). The review suggests that the pattern of correlation between the two basic postfire persistent traits and other plant traits varies between continents and ecosystems. From these results we predict, for instance, that not all resprouters respond in a similar way everywhere because the associated plant traits of resprouter species vary in different places. Thus, attempts to generalize predictions on the basis of the resprouting capacity may have limited power at a global scale. An example is presented for Australian heathlands. Considering the combination of persistence at individual (resprouting) and at population (seed bank) level, the predictive power at local scale was significantly increased.

Validating the Malheur model for predicting ponderosa pine post-fire mortality using 24 fires in the Pacific Northwest, USA

Treesearch

Walter G. Thies; Douglas J. Westlind

2012-01-01

Fires, whether intentionally or accidentally set, commonly occur in western interior forests of the US. Following fire, managers need the ability to predict mortality of individual trees based on easily observed characteristics. Previously, a two-factor model using crown scorch and bole scorch proportions was developed with data from 3415 trees for predicting the...

Increased fire frequency promotes stronger spatial genetic structure and natural selection at regional and local scales in Pinus halepensis Mill.

PubMed

Budde, Katharina B; González-Martínez, Santiago C; Navascués, Miguel; Burgarella, Concetta; Mosca, Elena; Lorenzo, Zaida; Zabal-Aguirre, Mario; Vendramin, Giovanni G; Verdú, Miguel; Pausas, Juli G; Heuertz, Myriam

2017-04-01

The recurrence of wildfires is predicted to increase due to global climate change, resulting in severe impacts on biodiversity and ecosystem functioning. Recurrent fires can drive plant adaptation and reduce genetic diversity; however, the underlying population genetic processes have not been studied in detail. In this study, the neutral and adaptive evolutionary effects of contrasting fire regimes were examined in the keystone tree species Pinus halepensis Mill. (Aleppo pine), a fire-adapted conifer. The genetic diversity, demographic history and spatial genetic structure were assessed at local (within-population) and regional scales for populations exposed to different crown fire frequencies. Eight natural P. halepensis stands were sampled in the east of the Iberian Peninsula, five of them in a region exposed to frequent crown fires (HiFi) and three of them in an adjacent region with a low frequency of crown fires (LoFi). Samples were genotyped at nine neutral simple sequence repeats (SSRs) and at 251 single nucleotide polymorphisms (SNPs) from coding regions, some of them potentially important for fire adaptation. Fire regime had no effects on genetic diversity or demographic history. Three high-differentiation outlier SNPs were identified between HiFi and LoFi stands, suggesting fire-related selection at the regional scale. At the local scale, fine-scale spatial genetic structure (SGS) was overall weak as expected for a wind-pollinated and wind-dispersed tree species. HiFi stands displayed a stronger SGS than LoFi stands at SNPs, which probably reflected the simultaneous post-fire recruitment of co-dispersed related seeds. SNPs with exceptionally strong SGS, a proxy for microenvironmental selection, were only reliably identified under the HiFi regime. An increasing fire frequency as predicted due to global change can promote increased SGS with stronger family structures and alter natural selection in P. halepensis and in plants with similar life history traits. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Space Radar Image of Yellowstone Park, Wyoming

NASA Image and Video Library

1999-05-01

These two radar images show the majestic Yellowstone National Park, Wyoming, the oldest national park in the United States and home to the world's most spectacular geysers and hot springs. The region supports large populations of grizzly bears, elk and bison. In 1988, the park was burned by one of the most widespread fires to occur in the northern Rocky Mountains in the last 50 years. Surveys indicated that 793,880 acres of land burned. Of that, 41 percent was burned forest, with tree canopies totally consumed by the fire; 35 percent was a combination of unburned, scorched and blackened trees; 13 percent was surface burn under an unburned canopy; 6 percent was non-forest burn; and 5 percent was undifferentiated burn. Six years later, the burned areas are still clearly visible in these false-color radar images obtained by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar on board the space shuttle Endeavour. The image at the left was obtained using the L-band radar channel, horizontally received and vertically transmitted, on the shuttle's 39th orbit on October 2, 1994. The area shown is 45 kilometers by 71 kilometers (28 miles by 44 miles) in size and centered at 44.6 degrees north latitude, 110.7 degrees west longitude. North is toward the top of the image (to the right). Most trees in this area are lodge pole pines at different stages of fire succession. Yellowstone Lake appears as a large dark feature at the bottom of the scene. At right is a map of the forest crown, showing its biomass, or amount of vegetation, which includes foliage and branches. The map was created by inverting SIR-C data and using in situ estimates of crown biomass gathered by the Yellowstone National Biological Survey. The map is displayed on a color scale from blue (rivers and lakes with no biomass) to brown (non-forest areas with crown biomass of less than 4 tons per hectare) to light brown (areas of canopy burn with biomass of between 4 and 12 tons per hectare). Yellow indicates areas of canopy burn and mixed burn with a biomass of between 12 to 20 tons per hectare; light green is mixed burn and on-burn forest with a biomass of 20 to 35 tons per hectare; and green is non-burned forest with a biomass of greater than 35 tons per hectare. Forest recovery from the fire seems to depend on fire intensity and soil conditions. In areas of severe canopy burn and poor soil conditions, crown biomass was still low in 1994 (indicated by the brown areas at the center left), whereas in areas of mixed burn with nutrient-rich soils, seen west of Yellowstone Lake, crown biomass has increased significantly in six years (indicated by the yellow and light green areas). Imaging fire-affected regions with spaceborne radar illustrates SIR-C/X-SAR's keen abilities to monitor regrowth after a fire. Knowing the amount of carbon accumulated in the atmosphere by regenerating forest in the 20 to 50 years following a fire disturbance is also a significant factor in understanding the global carbon cycle. Measuring crown biomass is necessary to evaluate the effects of past and future fires in specific regions. http://photojournal.jpl.nasa.gov/catalog/PIA01741

Role of fire in restoration of a ponderosa pine forest, Washington

Treesearch

Richy J. Harrod; Richard W. Fonda; Mara K. McGrath

2007-01-01

Ponderosa pine forests in the Eastern Cascades of Washington support dense, overstocked stands in which crown fires are probable, owing to postsettlement sheep grazing, logging, and fire exclusion. In 1991, the Okanogan-Wenatchee National Forests began to apply long-term management techniques to reverse postsettlement changes in ponderosa pine forests. For 9 years, the...

Tree-centered spot firing - a technique for prescribed burning beneath standing trees.

Treesearch

C. Phillip Weatherspoon; George A. Almond; Carl N. Skinner

1989-01-01

Prescribed burning beneath standing trees normally requires efforts to protect residual trees from excessive fire damage. Damage to both crowns and boles is strongly influenced by flame length, a fire characteristic functionally related to fireline intensity (Albini 1976). In a good prescribed burn, therefore, the prescription specifies desired or maximum flame lengths...

Documenting PyroCb Development on High-Intensity Boreal Fires: Implications for the Arctic Atmosphere

NASA Astrophysics Data System (ADS)

Stocks, B. J.; Fromm, M. D.; Servranckx, R.; Lindsey, D.

2007-12-01

The recent confirmation that smoke from high-intensity boreal forest fires can reach the Upper Troposphere/Lower Stratosphere (UTLS) through pyroconvection and be transported long distances has raised concern over the wider-scale environmental impact of boreal fire smoke. This concern is further elevated as climate change projections indicate a significant increase in the frequency and severity of boreal forest fires over the next century. Smoke in the UTLS is frequently transported to the Arctic and may have important implications for the radiative energy budget in the polar region. Soot deposition from fires may lead to enhanced melting of sea ice and glaciers, and the chemical impact of fire emissions at high altitudes is largely unknown. This knowledge gap will be addressed during the International Polar Year (IPY), as boreal fire emissions will be tracked and documented in detail through aerial, satellite and ground-based measurements, as a key component of the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) and ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) projects to be conducted in 2008. A large fire in the Canadian Northwest Territories burned throughout the month of June 2007, in a remote region where forest fires are not actively suppressed, eventually reaching 90,000 hectares in size. This fire was monitored for blowup one week in advance; it erupted into pyroconvection on June 25, 2007. We present an analysis of this event combining satellite data with ground-based measurements to document the development and impact of this classic pyroCb event. Under extreme fire danger conditions, the fire burned close to 20,000 hectares on that day. Fire behavior was consistent with predictions using the Canadian Fire Behavior Prediction System, with the fire spreading at 2.7 km/hr, consuming 33,000 kg of fuel hourly, generating an energy release rate of ~45,000 kW/m. This constitutes a typical high-intensity boreal crown fire, common across northern Canada every summer, and often capable of producing independent pyroconvection. The June 25 blowup was monitored using OMI AI, CALIPSO, Aqua MODIS, AVHRR and GOES satellite imagery, and these measurements validated the predicted fire behavior, including the development of a convection column that rose 10-11 km and injected smoke within the UTLS. Over subsequent days this smoke spread to Arctic latitudes (70-80 degrees N).

Piloted ignition of live forest fuels

Treesearch

S. McAllister; I. Grenfell; A. Hadlow; W. M. Jolly; M. Finney; J. Cohen

2012-01-01

The most unpredictable and uncontrollable wildfires are those that burn in the crowns of live vegetation. The fuels that feed these crown fires are mostly live, green foliage. Unfortunately, little is known about how live fuels combust. To understand how live fuels burn, piloted ignition experiments were performed with lodgepole pine and Douglas-fir. The thermal...

Ecological restoration of southwestern ponderosa pine ecosystems: A broad perspective

USGS Publications Warehouse

Allen, Craig D.; Savage, Melissa; Falk, Donald A.; Suckling, Kieran F.; Swetnam, Thomas W.; Schulke, Todd; Stacey, Peter B.; Morgan, Penelope; Hoffman, Martos; Klingel, Jon T.

2002-01-01

The purpose of this paper is to promote a broad and flexible perspective on ecological restoration of Southwestern (U.S.) ponderosa pine forests. Ponderosa pine forests in the region have been radically altered by Euro-American land uses, including livestock grazing, fire suppression, and logging. Dense thickets of young trees now abound, old-growth and biodiversity have declined, and human and ecological communities are increasingly vulnerable to destructive crown fires. A consensus has emerged that it is urgent to restore more natural conditions to these forests. Efforts to restore Southwestern forests will require extensive projects employing varying combinations of young-tree thinning and reintroduction of low-intensity fires. Treatments must be flexible enough to recognize and accommodate: high levels of natural heterogeneity; dynamic ecosystems; wildlife and other biodiversity considerations; scientific uncertainty; and the challenges of on-the-ground implementation. Ecological restoration should reset ecosystem trends toward an envelope of “natural variability,” including the reestablishment of natural processes. Reconstructed historic reference conditions are best used as general guides rather than rigid restoration prescriptions. In the long term, the best way to align forest conditions to track ongoing climate changes is to restore fire, which naturally correlates with current climate. Some stands need substantial structural manipulation (thinning) before fire can safely be reintroduced. In other areas, such as large wilderness and roadless areas, fire alone may suffice as the main tool of ecological restoration, recreating the natural interaction of structure and process. Impatience, overreaction to crown fire risks, extractive economics, or hubris could lead to widespread application of highly intrusive treatments that may further damage forest ecosystems. Investments in research and monitoring of restoration treatments are essential to refine restoration methods. We support the development and implementation of a diverse range of scientifically viable restoration approaches in these forests, suggest principles for ecologically sound restoration that immediately reduce crown fire risk and incrementally return natural variability and resilience to Southwestern forests, and present ecological perspectives on several forest restoration approaches.

Fire management of California shrubland landscapes

USGS Publications Warehouse

Keeley, Jon E.

2002-01-01

Fire management of California shrublands has been heavily influenced by policies designed for coniferous forests, however, fire suppression has not effectively excluded fire from chaparral and coastal sage scrub landscapes and catastrophic wildfires are not the result of unnatural fuel accumulation. There is no evidence that prescribed burning in these shrublands provides any resource benefit and in some areas may negatively impact shrublands by increasing fire frequency. Therefore, fire hazard reduction is the primary justification for prescription burning, but it is doubtful that rotational burning to create landscape age mosaics is a cost effective method of controlling catastrophic wildfires. There are problems with prescription burning in this crown-fire ecosystem that are not shared by forests with a natural surface-fire regime. Prescription weather conditions preclude burning at rotation intervals sufficient to effect the control of fires ignited under severe weather conditions. Fire management should focus on strategic placement of prescription burns to both insure the most efficient fire hazard reduction and to minimize the amount of landscape exposed to unnaturally high fire frequency. A major contributor to increased fire suppression costs and increased loss of property and lives is the continued urban sprawl into wildlands naturally subjected to high intensity crown fires. Differences in shrubland fire history suggest there may be a need for different fire management tactics between central coastal and southern California. Much less is known about shrubland fire history in the Sierra Nevada foothills and interior North Coast Ranges, and thus it would be prudent to not transfer these ideas too broadly across the range of chaparral until we have a clearer understanding of the extent of regional variation in shrubland fire regimes.

Fire management of California shrubland landscapes.

PubMed

Keeley, Jon E

2002-03-01

Fire management of California shrublands has been heavily influenced by policies designed for coniferous forests, however, fire suppression has not effectively excluded fire from chaparral and coastal sage scrub landscapes and catastrophic wildfires are not the result of unnatural fuel accumulation. There is no evidence that prescribed burning in these shrublands provides any resource benefit and in some areas may negatively impact shrublands by increasing fire frequency. Therefore, fire hazard reduction is the primary justification for prescription burning, but it is doubtful that rotational burning to create landscape age mosaics is a cost effective method of controlling catastrophic wildfires. There are problems with prescription burning in this crown-fire ecosystem that are not shared by forests with a natural surface-fire regime. Prescription weather conditions preclude burning at rotation intervals sufficient to effect the control of fires ignited under severe weather conditions. Fire management should focus on strategic placement of prescription burns to both insure the most efficient fire hazard reduction and to minimize the amount of landscape exposed to unnaturally high fire frequency. A major contributor to increased fire suppression costs and increased loss of property and lives is the continued urban sprawl into wildlands naturally subjected to high intensity crown fires. Differences in shrubland fire history suggest there may be a need for different fire management tactics between central coastal and southern California. Much less is known about shrubland fire history in the Sierra Nevada foothills and interior North Coast Ranges, and thus it would be prudent to not transfer these ideas too broadly across the range of chaparral until we have a clearer understanding of the extent of regional variation in shrubland fire regimes.

Repeated Stand-Replacing Crown Fires Affect Seed Morphology and Germination in Aleppo pine.

PubMed

Saracino, Antonio; Bellino, Alessandro; Allevato, Emilia; Mingo, Antonio; Conti, Stefano; Rossi, Sergio; Bonanomi, Giuliano; Carputo, Domenico; Mazzoleni, Stefano

2017-01-01

Post-fire reproductive niche of Aleppo pine ( Pinus halepensis ) is deeply interlaced with fire products. Indeed, the high pH and low osmotic potentials of ash beds under burnt crowns constitute the main constraints to seed germination. In this study, we aim to investigate whether fire recurrence, through the physico-chemical constraints imposed by the ash beds, affects the reproduction ability of P. halepensis at the germination stage. To this aim, Aleppo pine seeds were collected in neighboring even-aged stands subjected to 0, 1, or 2 fires (namely fire cohorts), and seed morphology and germination performance, in terms of cumulative germination and germination kinetics, were studied under increasing osmotic potentials (from 0.0 to -1.2 MPa) and pH (from 6 to 11). Besides fire history, the role of ontogenetic age of mother plants on seed morphology and germination was also investigated. Differences in seed morphology among the three cohorts have been highlighted in a multivariate context, with anisotropic enlargement of the seeds produced by pine stands experiencing repeated fires. The patterns of seed germination varied primarily in relation to the fire cohort, with seeds from the pine stand experiencing repeated fires exhibiting enhanced tolerance to pH stress. Conversely, germination performances under osmotic constraints mainly depends on tree ontogenetic stage, with an involvement of fire history especially in the timing of seed germination. Our results suggest that, at least in the short term, fire recurrence does not constrain the reproduction ability of Aleppo pine. These results highlight the need for further research to elucidate the mechanisms behind these responses to recurrent fires.

An investigation of surface and crown fire dynamics in shrub fuels

Treesearch

Jesse Sandoval Lozano

2011-01-01

Fires burn large areas in California and around the world annually. California experiences numerous wildland fires that affect the lives of thousands of citizens every year. In 2000 the U.S. census bureau reported that 33.8 million people resided in California. The last census in 2010 showed California population had grown to 37.3 million people. As a consequence of...

Early dynamics of table mountain pine stands following stand-replacement prescribed fires of varying intensity

Treesearch

Thomas A. Waldrop; Helen H. Mohr; Patrick H. Brose

2006-01-01

Interest in using stand-replacement prescribed fires to regenerate stands of Table Mountain pine (Pinus pungens Lamb.) has increased in the past decade, but the type and intensity of fire needed to achieve success have been undefined. In an earlier paper, we concluded from first-year results that flames must reach into the crowns to kill most...

Fire Monitoring: Effects of Scorch in Louisiana's Pine Forests

Treesearch

James D. Haywood; Mary Anne Sword; Finis L. Harris

2004-01-01

Frequent growing-season burning is essential for restoring longleaf pine (Pinus palustris Mill.) plant communities to open parklike landscapes. However, fire can be a destructive force, reducing productivity and causing mortality among overstory longleaf pine trees. On two central Louisiana sites, severe crown scorch reduced longleaf pine diameter...

Foliar Moisture Contents of North American Conifers

Treesearch

Christopher R. Keyes

2006-01-01

Foliar moisture content (FMC) is a primary factor in the canopy ignition process as surface fire transitions to crown fire. In combination with measured stand data and assumed environmental conditions, reasonable estimates of foliar moisture content are necessary to determine and justify silvicultural targets for canopy fuels management strategies. FMC values reported...

Corona Borealis

NASA Astrophysics Data System (ADS)

Murdin, P.

2000-11-01

(the Northern Crown; abbrev. CrB, gen. Coronae Borealis; area 179 sq. deg.) A northern constellation which lies between Boötes and Hercules, and culminates at midnight in mid-May. It represents the crown that in Greek mythology was made by Hephaestus, god of fire, and worn by Princess Ariadne of Crete. Its brightest stars were cataloged by Ptolemy (c. AD 100-175) in the Almagest....

Trend of mountain big Sagebrush crown cover and ground cover on burned sites, Uinta Mountains and West Tavaputs Plateau, Utah

Treesearch

Sherel Goodrich; Allen Huber; Brian Monroe

2008-01-01

Photography and notes on file at the Supervisors Office, Ashley National Forest make it possible to date many fires in mountain big sagebrush (Artemisia tridentata ssp. vaseyana) communities on this National Forest. Crown cover of mountain big sagebrush and other shrubs was measured in repeat visits to many burned sites. Burned...

Repeated Stand-Replacing Crown Fires Affect Seed Morphology and Germination in Aleppo pine

PubMed Central

Saracino, Antonio; Bellino, Alessandro; Allevato, Emilia; Mingo, Antonio; Conti, Stefano; Rossi, Sergio; Bonanomi, Giuliano; Carputo, Domenico; Mazzoleni, Stefano

2017-01-01

Post-fire reproductive niche of Aleppo pine (Pinus halepensis) is deeply interlaced with fire products. Indeed, the high pH and low osmotic potentials of ash beds under burnt crowns constitute the main constraints to seed germination. In this study, we aim to investigate whether fire recurrence, through the physico-chemical constraints imposed by the ash beds, affects the reproduction ability of P. halepensis at the germination stage. To this aim, Aleppo pine seeds were collected in neighboring even-aged stands subjected to 0, 1, or 2 fires (namely fire cohorts), and seed morphology and germination performance, in terms of cumulative germination and germination kinetics, were studied under increasing osmotic potentials (from 0.0 to −1.2 MPa) and pH (from 6 to 11). Besides fire history, the role of ontogenetic age of mother plants on seed morphology and germination was also investigated. Differences in seed morphology among the three cohorts have been highlighted in a multivariate context, with anisotropic enlargement of the seeds produced by pine stands experiencing repeated fires. The patterns of seed germination varied primarily in relation to the fire cohort, with seeds from the pine stand experiencing repeated fires exhibiting enhanced tolerance to pH stress. Conversely, germination performances under osmotic constraints mainly depends on tree ontogenetic stage, with an involvement of fire history especially in the timing of seed germination. Our results suggest that, at least in the short term, fire recurrence does not constrain the reproduction ability of Aleppo pine. These results highlight the need for further research to elucidate the mechanisms behind these responses to recurrent fires. PMID:28713415

Coexistence of Trees and Grass: Importance of climate and fire within the tropics

NASA Astrophysics Data System (ADS)

Shuman, J. K.; Fisher, R.; Koven, C.; Knox, R. G.; Andre, B.; Kluzek, E. B.

2017-12-01

Tropical forests are characterized by transition zones where dominance shifts between trees and grasses with some areas exhibiting bistability of the two. The cause of this transition and bistability has been linked to the interacting effects of climate, vegetation structure and fire behavior. Utilizing the Functionally Assembled Terrestrial Ecosystem Simulator (FATES), a demographic vegetation model, and the CESM ESM, we explore the coexistence of trees and grass across the tropics with an active fire regime. FATES has been updated to use a fire module based on Spitfire. FATES-Spitfire tracks fire ignition, spread and impact based on fuel state and combustion. Fire occurs within the model with variable intensity that kills trees according to the combined effects of cambial damage and crown scorch due to flame height and fire intensity. As a size-structured model, FATES allows for variable mortality based on the size of tree cohorts, where larger trees experience lower morality compared to small trees. Results for simulation scenarios where vegetation is represented by all trees, all grass, or a combination of competing trees and grass are compared to assess changes in biomass, fire regime and tree-grass coexistence. Within the forest-grass transition area there is a critical time during which grass fuels fire spread and prevents the establishment of trees. If trees are able to escape mortality a tree-grass bistable area is successful. The ability to simulate the bistability and transition of trees and grass throughout the tropics is critical to representing vegetation dynamics in response to changing climate and CO2.

The effect of porcelain firing and type of finish line on the marginal fit of zirconia copings.

PubMed

Vojdani, Mahroo; Safari, Anahita; Mohaghegh, Mina; Pardis, Soheil; Mahdavi, Farideh

2015-06-01

Although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. The purpose of this study was to evaluate the marginal fit of zirconia CAD/CAM ceramic crowns before and after porcelain firing. The influence of finish line configuration on the marginal fit was also evaluated. Twenty standardized zirconia CAD/CAM copings were fabricated for chamfer and shoulder finish line designs (n=10). The marginal fit of specimens was measured on 18 points, marked on the master metal die by using a digital microscope. After the crowns were finalized by porcelain veneering, the measurements of marginal fit were performed again. The means and standard deviations were calculated and data were analyzed using student's t-test and paired t-test (α=0.05). There were significant differences between marginal fit of chamfer and shoulder finish line groups before and after porcelain firing (p= 0.014 and p= 0.000, respectively). The marginal gap of copings with shoulder finish line was significantly smaller than those with chamfer configuration (p= 0.000), but there were no significant differences between the two marginal designs, after porcelain firing (p= 0.341). Porcelain veneering was found to have a statistically significant influence on the marginal fit of zirconia CAD/CAM crowns. Both margin configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.

A 6 year longitudinal study of post-fire woody carbon dynamics in California's forests

Treesearch

Bianca N.I. Eskelson; Vicente J. Monleon; Jeremy S. Fried

2016-01-01

We examined the dynamics of aboveground forest woody carbon pools — live trees, standing dead trees, and down wood—during the first 6 years following wildfire across a wide range of conditions, which are characteristic of California forest fires. From repeated measurements of the same plots, we estimated change in woody carbon pools as a function of crown fire severity...

Intensifying postfire weather and biological invasion drive species loss in a Mediterranean-type biodiversity hotspot.

PubMed

Slingsby, Jasper A; Merow, Cory; Aiello-Lammens, Matthew; Allsopp, Nicky; Hall, Stuart; Kilroy Mollmann, Hayley; Turner, Ross; Wilson, Adam M; Silander, John A

2017-05-02

Prolonged periods of extreme heat or drought in the first year after fire affect the resilience and diversity of fire-dependent ecosystems by inhibiting seed germination or increasing mortality of seedlings and resprouting individuals. This interaction between weather and fire is of growing concern as climate changes, particularly in systems subject to stand-replacing crown fires, such as most Mediterranean-type ecosystems. We examined the longest running set of permanent vegetation plots in the Fynbos of South Africa (44 y), finding a significant decline in the diversity of plots driven by increasingly severe postfire summer weather events (number of consecutive days with high temperatures and no rain) and legacy effects of historical woody alien plant densities 30 y after clearing. Species that resprout after fire and/or have graminoid or herb growth forms were particularly affected by postfire weather, whereas all species were sensitive to invasive plants. Observed differences in the response of functional types to extreme postfire weather could drive major shifts in ecosystem structure and function such as altered fire behavior, hydrology, and carbon storage. An estimated 0.5 °C increase in maximum temperature tolerance of the species sets unique to each survey further suggests selection for species adapted to hotter conditions. Taken together, our results show climate change impacts on biodiversity in the hyperdiverse Cape Floristic Region and demonstrate an important interaction between extreme weather and disturbance by fire that may make flammable ecosystems particularly sensitive to climate change.

Landscape Scale Influences of Forest Area and Housing Density on House Loss in the 2009 Victorian Bushfires

PubMed Central

Price, Owen; Bradstock, Ross

2013-01-01

Previous investigations into the factors associated with house loss in wildfires have focused on the house construction and its immediate environment (e.g. gardens). Here, we examine how nearby native forest and other houses can influence house loss. Specifically, we used a sample of 3500 houses affected by the Victorian bushfires of February 7th 2009 to explore how the amount of forest, proportion of forest burned by crown fire and the number of nearby houses affected house loss and how far from the house this influence was exerted. These fires were the most destructive in Australian history and so represent the extreme of fire risk. Using generalized linear modeling we found that the probability of house loss increased with forest extent and the proportion burnt by crown fire and this relationship was strongest for forest measured 1 km from the houses. Houses were more likely to be destroyed if there were other houses within 50 m and if they were on a slope. A model containing these variables predicted house loss with 72% accuracy. Our findings have three important implications: i) management to change the occurrence of crown fire will be effective in reducing house loss; ii) this management may be required up to 1 km away from houses in some situations (a much larger zone than is currently used); iii) high density of houses may increase risk of loss. Given the potentially large width of this management zone and the hazard from nearby houses, it may be more sensible to concentrate on modification of buildings to reduce their vulnerability. PMID:24009753

The efficacy of fuel treatment in mitigating property loss during wildfires: Insights from analysis of the severity of the catastrophic fires in 2009 in Victoria, Australia.

PubMed

Price, Owen F; Bradstock, Ross A

2012-12-30

Treatment of fuel (e.g. prescribed fire, logging) in fire-prone ecosystems is done to reduce risks to people and their property but effects require quantification, particularly under severe weather conditions when the destructive potential of fires on human infrastructure is maximised. We analysed the relative effects of fuel age (i.e. indicative of the effectiveness of prescribed fire) and logging on remotely sensed (SPOT imagery) severity of fires which occurred in eucalypt forests in Victoria, Australia in 2009. These fires burned under the most severe weather conditions recorded in Australia and caused large losses of life and property. Statistical models of the probability of contrasting extremes of severity (crown fire versus fire confined to the understorey) were developed based on effects of fuel age, logging, weather, topography and forest type. Weather was the primary influence on severity, though it was reduced at low fuel ages in Moderate but not Catastrophic, Very High or Low fire-weather conditions. Probability of crown fires was higher in recently logged areas than in areas logged decades before, indicating likely ineffectiveness as a fuel treatment. The results suggest that recently burnt areas (up to 5-10 years) may reduce the intensity of the fire but not sufficiently to increase the chance of effective suppression under severe weather conditions. Since house loss was most likely under these conditions (67%), effects of prescribed burning across landscapes on house loss are likely to be small when weather conditions are severe. Fuel treatments need to be located close to houses in order to effectively mitigate risk of loss. Copyright © 2012 Elsevier Ltd. All rights reserved.

Fire and longleaf pine physiology - Does timing affect response? In: Proc

Treesearch

Mary Anne Sword Sayer; James D. Haywood

2009-01-01

Southern pines vary in their response to the loss of leaf area by crown scorch. We hypothesize that they tolerate crown scorch by at least three recovery mechanisms, but the function of these mechanisms is season-dependent. Using sapling longleaf pine as a model and experimental results from central Louisiana, U.S.A., our objective is to present examples recovery from...

Variation in Surface and Crown Fire Hazard With Stand Age in Managed Coastal Western Hemlock Zone Forests in Southwestern British Columbia

Treesearch

Michael C. Feller; Stefanie L. Pollock

2006-01-01

Surface and crown fuels were measured in 186 stands ranging in age from 0 years after clearcutting to old-growth forests > 300 years old in Douglas-fir (Pseudotsuga menziesii) – western hemlock (Tsuga heterophylla) – western redcedar (Thuja plicata) – dominated forests in southwestern British Columbia. Indexes...

An assessment of factors associated with damage to tree crowns from the 1987 wildfires in northern California

Treesearch

C. Phillip Weatherspoon; Carl N. Skinner

1995-01-01

Relationships between (1) degree of damage caused by the 1987 fires in northern California and (2) prior management activities, fuelbed characteristics, and site/stand factors were studied on the Hayfork Ranger District of the Shasta-Trinity National Forests. Postfire aerial photography was used to assess scorch and consumption of tree crowns (the selected measure of...

Post-Disturbance Plant Community Dynamics following a Rare Natural-Origin Fire in a Tsuga canadensis Forest

PubMed Central

Murray, Bryan D.; Holmes, Stacie A.; Webster, Christopher R.; Witt, Jill C.

2012-01-01

Opportunities to directly study infrequent forest disturbance events often lead to valuable information about vegetation dynamics. In mesic temperate forests of North America, stand-replacing crown fire occurs infrequently, with a return interval of 2000–3000 years. Rare chance events, however, may have profound impacts on the developmental trajectories of forest ecosystems. For example, it has been postulated that stand-replacing fire may have been an important factor in the establishment of eastern hemlock (Tsuga canadensis) stands in the northern Great Lakes region. Nevertheless, experimental evidence linking hemlock regeneration to non-anthropogenic fire is limited. To clarify this potential relationship, we monitored vegetation dynamics following a rare lightning-origin crown fire in a Wisconsin hemlock-hardwood forest. We also studied vegetation in bulldozer-created fire breaks and adjacent undisturbed forest. Our results indicate that hemlock establishment was rare in the burned area but moderately common in the scarified bulldozer lines compared to the reference area. Early-successional, non-arboreal species including Rubus spp., Vaccinium angustifolium, sedges (Carex spp.), grasses, Epilobium ciliatum, and Pteridium aquilinium were the most abundant post-fire species. Collectively, our results suggest that competing vegetation and moisture stress resulting from drought may reduce the efficacy of scarification treatments as well as the usefulness of fire for preparing a suitable seedbed for hemlock. The increasing prevalence of growing-season drought suggests that silvicultural strategies based on historic disturbance regimes may need to be reevaluated for mesic species. PMID:22928044

Fuels planning: science synthesis and integration; forest structure and fire hazard fact sheet 06: Guide to fuel treatments in dry forests of the Western United States: assessing forest structure and fire hazard

Treesearch

Rocky Mountain Research Station USDA Forest Service

2005-01-01

The Guide to Fuel Treatments analyzes a range of potential silvicultural thinnings and surface fuel treatments for 25 representative dry-forest stands in the Western United States. The guide provides quantitative guidelines and visualization for treatment based on scientific principles identified for reducing potential crown fires. This fact sheet identifies the...

Climate effects on fire regimes and tree recruitment in Black Hills ponderosa pine forests.

PubMed

Brown, Peter M

2006-10-01

Climate influences forest structure through effects on both species demography (recruitment and mortality) and disturbance regimes. Here, I compare multi-century chronologies of regional fire years and tree recruitment from ponderosa pine forests in the Black Hills of southwestern South Dakota and northeastern Wyoming to reconstructions of precipitation and global circulation indices. Regional fire years were affected by droughts and variations in both Pacific and Atlantic sea surface temperatures. Fires were synchronous with La Niñas, cool phases of the Pacific Decadal Oscillation (PDO), and warm phases of the Atlantic Multidecadal Oscillation (AMO). These quasi-periodic circulation features are associated with drought conditions over much of the western United States. The opposite pattern (El Niño, warm PDO, cool AMO) was associated with fewer fires than expected. Regional tree recruitment largely occurred during wet periods in precipitation reconstructions, with the most abundant recruitment coeval with an extended pluvial from the late 1700s to early 1800s. Widespread even-aged cohorts likely were not the result of large crown fires causing overstory mortality, but rather were caused by optimal climate conditions that contributed to synchronous regional recruitment and longer intervals between surface fires. Synchronous recruitment driven by climate is an example of the Moran effect. The presence of abundant fire-scarred trees in multi-aged stands supports a prevailing historical model for ponderosa pine forests in which recurrent surface fires affected heterogenous forest structure, although the Black Hills apparently had a greater range of fire behavior and resulting forest structure over multi-decadal time scales than ponderosa pine forests of the Southwest that burned more often.

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure

PubMed Central

Miquelajauregui, Yosune; Cumming, Steven G.; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity. PMID:26919456

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure.

PubMed

Miquelajauregui, Yosune; Cumming, Steven G; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity.

Patterns in woody vegetation structure across African savannas

NASA Astrophysics Data System (ADS)

Axelsson, Christoffer R.; Hanan, Niall P.

2017-07-01

Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP) modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs), which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality), soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (< 200 mm yr-1) to the wettest (1200-1400 mm yr-1) end, mean estimates of crown size, crown density, and woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand content suggesting that maximal savanna tree sizes do not occur in either coarse sands or heavy clays. When examining the occurrence of PVPs, we found that the same factors that contribute to the formation of PVPs also correlate with higher levels of woody plant aggregation elsewhere in savannas and that rainfall seasonality plays a key role for the underlying processes.

Temperate and boreal forest mega-fires: characteristics and challenges

USGS Publications Warehouse

Stephens, Scott L.; Burrows, Neil; Buyantuyev, Alexander; Gray, Robert W.; Keane, Robert E.; Kubian, Rick; Liu, Shirong; Seijo, Francisco; Shu, Lifu; Tolhurst, Kevin G.; Van Wagtendonk, Jan W.

2014-01-01

Mega-fires are often defined according to their size and intensity but are more accurately described by their socioeconomic impacts. Three factors – climate change, fire exclusion, and antecedent disturbance, collectively referred to as the “mega-fire triangle” – likely contribute to today's mega-fires. Some characteristics of mega-fires may emulate historical fire regimes and can therefore sustain healthy fire-prone ecosystems, but other attributes decrease ecosystem resiliency. A good example of a program that seeks to mitigate mega-fires is located in Western Australia, where prescribed burning reduces wildfire intensity while conserving ecosystems. Crown-fire-adapted ecosystems are likely at higher risk of frequent mega-fires as a result of climate change, as compared with other ecosystems once subject to frequent less severe fires. Fire and forest managers should recognize that mega-fires will be a part of future wildland fire regimes and should develop strategies to reduce their undesired impacts.

Physiological and Growth Responses of Midrotation Loblolly Pine to Treatments of Fire, Herbicide, and Fertilizer

Treesearch

Emily J. Goodwin; Lisa M. Marino McInnis; Hans M. Williams; Brian P. Oswald; Kenneth W. Farrish

2004-01-01

The objectives of this study were to examine the effects of fertilizer and understory vegetation control (herbicide and prescribed fire) on mature tree physiology and to link observed physiological responses with tree growth. Photosynthetic rate (photosynthesis), transpiration, stomatal conductance, stem diameter, and crown area were measured in two midrotation...

Five southern California oaks: identification and postfire management

Treesearch

Timothy R. Plumb; Anthony P. Gomez

1983-01-01

Oak trees in California are subject to periodic burning by fire, but their trunks and crowns vary in tolerance to fire. And once burned, oaks are difficult to identify by species. Fifteen oak species grow in California. This report provides keys to identifying five species of southern California oaks: coast live oak (Quercus agrifolia Née...

Fire, ice, and metabolism

Treesearch

Kevin T. Smith

2015-01-01

Evaluation of tree injury often begins with a loss assessment. For winter storm injury, percent crow loss or branch breakage is often estimated. For injury from fire or some mechanical source to the lower trunk, the height and width of the killed vascular cambium and resulting scar are often measured. Both crown breakage and stem wounds provide the opportunity for...

Thinning – a tool for restoration of California's Southern Sierra Nevada blue oak woodlands

Treesearch

Richard B. Standiford; Ralph L. Phillips; Neil K. McDougald

2015-01-01

Fire frequency on a blue oak (Quercus douglasii) dominated rangeland in California's southern Sierra Nevada foothills was approximately every 10 years until 1965, followed by a 30 year period of fire exclusion. This resulted in a dense tree overstory with small diameters, high crown cover, poor acorn and forage production, and limited...

The Effect of Porcelain Firing and Type of Finish Line on the Marginal Fit of Zirconia Copings

PubMed Central

Vojdani, Mahroo; Safari, Anahita; Mohaghegh, Mina; Pardis, Soheil; Mahdavi, Farideh

2015-01-01

Statement of the Problem Although all-ceramic restorations are broadly used, there is a lack of information concerning how their fit is affected by fabrication procedure and marginal configuration. Purpose The purpose of this study was to evaluate the marginal fit of zirconia CAD/CAM ceramic crowns before and after porcelain firing. The influence of finish line configuration on the marginal fit was also evaluated. Materials and Method Twenty standardized zirconia CAD/CAM copings were fabricated for chamfer and shoulder finish line designs (n=10). The marginal fit of specimens was measured on 18 points, marked on the master metal die by using a digital microscope. After the crowns were finalized by porcelain veneering, the measurements of marginal fit were performed again. The means and standard deviations were calculated and data were analyzed using student’s t-test and paired t-test (α=0.05). Results There were significant differences between marginal fit of chamfer and shoulder finish line groups before and after porcelain firing (p= 0.014 and p= 0.000, respectively). The marginal gap of copings with shoulder finish line was significantly smaller than those with chamfer configuration (p= 0.000), but there were no significant differences between the two marginal designs, after porcelain firing (p= 0.341). Conclusion Porcelain veneering was found to have a statistically significant influence on the marginal fit of zirconia CAD/CAM crowns. Both margin configurations showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy. PMID:26046107

Climatic stress increases forest fire severity across the western United States

USGS Publications Warehouse

van Mantgem, Philip J.; Nesmith, Jonathan C. B.; Keifer, MaryBeth; Knapp, Eric E.; Flint, Alan; Flint, Lorraine

2013-01-01

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire).

Numerical study of propagation of forest fires in the presence of fire breaks using an averaged setting

NASA Astrophysics Data System (ADS)

Marzaeva, S. I.; Galtseva, O. V.

2018-05-01

The forest fires spread in the pine forests have been numerically simulated using a three-dimensional mathematical model. The model was integrated with respect to the vertical coordinate because horizontal sizes of forest are much greater than the heights of trees. In this paper, the assignment and theoretical investigations of the problems of crown forest fires spread pass the firebreaks were carried out. In this context, a study ( mathematical modeling) of the conditions of forest fire spreading that would make it possible to obtain a detailed picture of the change in the temperature and component concentration fields with time, and determine as well as the limiting condition of fire propagation in forest with these fire breaks.

Estimating canopy bulk density and canopy base height for conifer stands in the interior Western United States using the Forest Vegetation Simulator Fire and Fuels Extension.

Treesearch

Seth Ex; Frederick Smith; Tara Keyser; Stephanie Rebain

2017-01-01

The Forest Vegetation Simulator Fire and Fuels Extension (FFE-FVS) is often used to estimate canopy bulk density (CBD) and canopy base height (CBH), which are key indicators of crown fire hazard for conifer stands in the Western United States. Estimated CBD from FFE-FVS is calculated as the maximum 4 m running mean bulk density of predefined 0.3 m thick canopy layers (...

Forty Years Of Prescribed Burning On The Santee Fire Plots: Effects On Understory Vegetation

Treesearch

David L. White; Thomas A. Waldrop; Steven M. Jones

1990-01-01

The effects of 43 years of repeated prescribed burning on crown cover, species composition, species richness, and diversity in the lower understory strata of the Santee Fire Plots were examined. Five study treatments, installed in 1946, include an unburned control, periodic winter and summer bums, and annual winter and summer bums. Understory cover has not changed in...

Fuels planning: science synthesis and integration; forest structure and fire hazard fact sheet 05: fuel treatment principles for complex landscapes

Treesearch

Rocky Mountain Research Station USDA Forest Service

2004-01-01

Appropriate types of thinning and surface fuel treatments are clearly useful in reducing surface and crown fire hazards under a wide range of fuels and topographic situations. This paper provides well-established scientific principles and simulation tools that can be used to adjust fuel treatments to attain specific risk levels.

Influence of repeated prescribed fire and herbicide application on the fine root biomass of young longleaf pine

Treesearch

Mary Anne Sword Sayer; Eric A. Kuehler

2010-01-01

Photosynthate from mature foliage provides the energy source necessary for longleaf pine (Pinus palustris Mill.) root system expansion. Crown scorch caused by repeated prescribed fire could decrease this energy and, in turn, reduce new root production. We conducted a study to assess the root biomass of restored longleaf pine saplings in response to...

Estimation of Forest Fuel Load from Radar Remote Sensing

NASA Technical Reports Server (NTRS)

Saatchi, Sassan; Despain, Don G.; Halligan, Kerry; Crabtree, Robert

2007-01-01

Understanding fire behavior characteristics and planning for fire management require maps showing the distribution of wildfire fuel loads at medium to fine spatial resolution across large landscapes. Radar sensors from airborne or spaceborne platforms have the potential of providing quantitative information about the forest structure and biomass components that can be readily translated to meaningful fuel load estimates for fire management. In this paper, we used multifrequency polarimetric synthetic aperture radar imagery acquired over a large area of the Yellowstone National Park (YNP) by the AIRSAR sensor, to estimate the distribution of forest biomass and canopy fuel loads. Semi-empirical algorithms were developed to estimate crown and stem biomass and three major fuel load parameters, canopy fuel weight, canopy bulk density, and foliage moisture content. These estimates when compared directly to measurements made at plot and stand levels, provided more than 70% accuracy, and when partitioned into fuel load classes, provided more than 85% accuracy. Specifically, the radar generated fuel parameters were in good agreement with the field-based fuel measurements, resulting in coefficients of determination of R(sup 2) = 85 for the canopy fuel weight, R(sup 2)=.84 for canopy bulk density and R(sup 2) = 0.78 for the foliage biomass.

Marginal Fit Comparison of CAD/CAM Crowns Milled from Two Different Materials.

PubMed

Azarbal, Atousa; Azarbal, Mohsen; Engelmeier, Robert L; Kunkel, Thomas C

2018-06-01

To evaluate the marginal fit of CAD/CAM copings milled from hybrid ceramic (Vita Enamic) blocks and lithium disilicate (IPS e.max CAD) blocks, and to evaluate the effect of crystallization firing on the marginal fit of lithium disilicate copings. A standardized metal die with a 1-mm-wide shoulder finish line was imaged using the CEREC AC Bluecam. The coping was designed using CEREC 3 software. The design was used to fabricate 15 lithium disilicate and 15 hybrid ceramic copings. Design and milling were accomplished by one operator. The copings were seated on the metal die using a pressure clamp with a uniform pressure of 5.5 lbs. A Macroview Microscope (14×) was used for direct viewing of the marginal gap. Four areas were imaged on each coping (buccal, distal, lingual, mesial). Image analysis software was used to measure the marginal gaps in μm at 15 randomly selected points on each of the four surfaces. A total of 60 measurements were made per specimen. For lithium disilicate copings the measurements for marginal gap were made before and after crystallization firing. Data were analyzed using paired t-test and Kruskal-Wallis test. The overall mean difference in marginal gap between the hybrid ceramic and crystallized lithium disilicate copings was statistically significant (p < 0.01). Greater mean marginal gaps were measured for crystallized lithium disilicate copings. The overall mean difference in marginal gap before and after firing (precrystallized and crystallized lithium disilicate copings) showed an average of 62 μm increase in marginal gap after firing. This difference was also significant (p < 0.01). A significant difference exists in the marginal gap discrepancy when comparing hybrid ceramic and lithium disilicate CAD/CAM crowns. Also crystallization firing can result in a significant increase in the marginal gap of lithium disilicate CAD/CAM crowns. © 2017 by the American College of Prosthodontists.

Forest Management Shifts in the Western US and Potential Impacts on the Carbon Balance

NASA Astrophysics Data System (ADS)

Law, B. E.; Jones, M. O.; Yang, Z.; Berner, L. T.

2015-12-01

Forest harvest regimes are changing as land managers cope with fires, drought, and insect damage. Thinning on public lands, typically focused on removal of small trees that could act as fuel ladders, is increasing to reduce risk of crown fires and reduce competition for water in crowded stands. On private lands, drought and wildfires could lead to further shortening of harvest cycles (e.g. from 80 to 45 years) or thinning. To examine the effects of potential changes in management regimes vs climate on carbon processes in forests of Oregon, California and Washington, we used data from ancillary plots, inventories, and satellites to parameterize and test the CLM4.5 model. We first examined contemporary biomass loss over the western US to determine the baseline conditions prior to implementing harvest scenarios. Annual biomass mortality from fires and insects increased significantly (1996-2011), and mortality from insects was about twice that of fires. California, Oregon and Idaho were most impacted by fire-related biomass mortality, whereas Colorado, Montana and Washington were most impacted by insects. Harvest scenarios implemented in CLM4.5 include two thinning scenarios to reduce crown fire risk and drought stress, and a salvage scenario to remove trees remaining after recent beetle or fire related mortality; taking into account our previous work showing 70 - 85 % of salvaged biomass is removed and the remainder is left on-site. We simulated the effect of treatments on current and future net ecosystem carbon balance. Challenges of regional modeling of management effects on carbon and other important considerations are addressed.

Fire severity and ecosytem responses following crown fires in California shrublands

USGS Publications Warehouse

Keeley, J.E.; Brennan, T.; Pfaff, A.H.

2008-01-01

Chaparral shrublands burn in large high-intensity crown fires. Managers interested in how these wildfires affect ecosystem processes generally rely on surrogate measures of fire intensity known as fire severity metrics. In shrublands burned in the autumn of 2003, a study of 250 sites investigated factors determining fire severity and ecosystem responses.Using structural equation modeling we show that stand age, prefire shrub density, and the shortest interval of the prior fire history had significant direct effects on fire severity, explaining >50% of the variation in severity.Fire severity per se is of interest to resource managers primarily because it is presumed to be an indicator of important ecosystem processes such as vegetative regeneration, community recovery, and erosion. Fire severity contributed relatively little to explaining patterns of regeneration after fire. Two generalizations can be drawn: fire severity effects are mostly short-lived, i.e., by the second year they are greatly diminished, and fire severity may have opposite effects on different functional types.Species richness exhibited a negative relationship to fire severity in the first year, but fire severity impacts were substantially less in the second postfire year and varied by functional type. Much of this relationship was due to alien plants that are sensitive to high fire severity; at all scales from 1 to 1000 m2, the percentage of alien species in the postfire flora declined with increased fire severity. Other aspects of disturbance history are also important determinants of alien cover and richness as both increased with the number of times the site had burned and decreased with time since last fire.A substantial number of studies have shown that remote-sensing indices are correlated with field measurements of fire severity. Across our sites, absolute differenced normalized burn ratio (dNBR) was strongly correlated with field measures of fire severity and with fire history at a site but relative dNBR was not. Despite being correlated with fire severity, absolute dNBR showed little or no relationship with important ecosystem responses to wildfire such as shrub resprouting or total vegetative regeneration. These findings point to a critical need for further research on interpreting remote sensing indices as applied to postfire management of these shrublands.

Fire severity and ecosytem responses following crown fires in California shrublands.

PubMed

Keeley, Jon E; Brennan, Teresa; Pfaff, Anne H

2008-09-01

Chaparral shrublands burn in large high-intensity crown fires. Managers interested in how these wildfires affect ecosystem processes generally rely on surrogate measures of fire intensity known as fire severity metrics. In shrublands burned in the autumn of 2003, a study of 250 sites investigated factors determining fire severity and ecosystem responses. Using structural equation modeling we show that stand age, prefire shrub density, and the shortest interval of the prior fire history had significant direct effects on fire severity, explaining > 50% of the variation in severity. Fire severity per se is of interest to resource managers primarily because it is presumed to be an indicator of important ecosystem processes such as vegetative regeneration, community recovery, and erosion. Fire severity contributed relatively little to explaining patterns of regeneration after fire. Two generalizations can be drawn: fire severity effects are mostly shortlived, i.e., by the second year they are greatly diminished, and fire severity may have opposite effects on different functional types. Species richness exhibited a negative relationship to fire severity in the first year, but fire severity impacts were substantially less in the second postfire year and varied by functional type. Much of this relationship was due to alien plants that are sensitive to high fire severity; at all scales from 1 to 1000 m2, the percentage of alien species in the postfire flora declined with increased fire severity. Other aspects of disturbance history are also important determinants of alien cover and richness as both increased with the number of times the site had burned and decreased with time since last fire. A substantial number of studies have shown that remote-sensing indices are correlated with field measurements of fire severity. Across our sites, absolute differenced normalized burn ratio (dNBR) was strongly correlated with field measures of fire severity and with fire history at a site but relative dNBR was not. Despite being correlated with fire severity, absolute dNBR showed little or no relationship with important ecosystem responses to wildfire such as shrub resprouting or total vegetative regeneration. These findings point to a critical need for further research on interpreting remote sensing indices as applied to postfire management of these shrublands.

Influences of stand structure and fuel treatments on wildfire severity at Blacks Mountain Experimental Forest, northeastern California

Treesearch

Julie N. Symons; Dean H. K. Fairbanks; Carl N. Skinner

2008-01-01

This study utilizes forest stand structures and fuel profiles to evaluate the influence of different types of silvicultural treatments on fire severity in the Blacks Mountain Experimental Forest (BMEF), located within Lassen National Forest of northeastern California. We compare the severity of fire, assessed based on tree crown and bole scorch on 100 ha experimental...

Seasonal variation in surface fuel moisture between unthinned and thinned mixed conifer forest, northern California, USA

Treesearch

Becky L. Estes; Eric E. Knapp; Carl N. Skinner; Fabian C. C. Uzoh

2012-01-01

Reducing stand density is often used as a tool for mitigating the risk of high-intensity crown fires. However, concern has been expressed that opening stands might lead to greater drying of surface fuels, contributing to increased fire risk. The objective of this study was to determine whether woody fuel moisture differed between unthinned and thinned mixed-conifer...

Surgical Tooth Implants, Combat and Field.

DTIC Science & Technology

1979-12-01

conventional dental materials, usually gold. Roots are produced by grinding bisque fired alumina stock on a computer controlled milling machine. This...post and core and crown) are conventional dental materials, usually gold. Roots are produced by grinding bisque fired alumina stock on a computer...of dental implants have evolved. These devices are designed to be rigidly affixed by bone ingrowth and provide minimization of stress usually by

Climatic stress increases forest fire severity across the western United States.

PubMed

van Mantgem, Phillip J; Nesmith, Jonathan C B; Keifer, MaryBeth; Knapp, Eric E; Flint, Alan; Flint, Lorriane

2013-09-01

Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our findings support recent physiological evidence showing that both drought and heating from fire can impair xylem conductivity. Warming trends have been linked to increasing probabilities of severe fire weather and fire spread; our results suggest that warming may also increase forest fire severity (the number of trees killed) independent of fire intensity (the amount of heat released during a fire). Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Examining fire-induced forest changes using novel remote sensing technique: a case study in a mixed pine-oak forest

NASA Astrophysics Data System (ADS)

Meng, R.; Wu, J.; Zhao, F. R.; Cook, B.; Hanavan, R. P.; Serbin, S.

2017-12-01

Fire-induced forest changes has long been a central focus for forest ecology and global carbon cycling studies, and is becoming a pressing issue for global change biologists particularly with the projected increases in the frequency and intensity of fire with a warmer and drier climate. Compared with time-consuming and labor intensive field-based approaches, remote sensing offers a promising way to efficiently assess fire effects and monitor post-fire forest responses across a range of spatial and temporal scales. However, traditional remote sensing studies relying on simple optical spectral indices or coarse resolution imagery still face a number of technical challenges, including confusion or contamination of the signal by understory dynamics and mixed pixels with moderate to coarse resolution data (>= 30 m). As such, traditional remote sensing may not meet the increasing demand for more ecologically-meaningful monitoring and quantitation of fire-induced forest changes. Here we examined the use of novel remote sensing technique (i.e. airborne imaging spectroscopy and LiDAR measurement, very high spatial resolution (VHR) space-borne multi-spectral measurement, and high temporal-spatial resolution UAS-based (Unmanned Aerial System) imagery), in combination with field and phenocam measurements to map forest burn severity across spatial scales, quantify crown-scale post-fire forest recovery rate, and track fire-induced phenology changes in the burned areas. We focused on a mixed pine-oak forest undergoing multiple fire disturbances for the past several years in Long Island, NY as a case study. We demonstrate that (1) forest burn severity mapping from VHR remote sensing measurement can capture crown-scale heterogeneous fire patterns over large-scale; (2) the combination of VHR optical and structural measurements provides an efficient means to remotely sense species-level post-fire forest responses; (3) the UAS-based remote sensing enables monitoring of fire-induced forest phenology changes at unprecedented temporal and spatial resolutions. This work provides the methodological approach monitor fire-induced forest changes in a spatially explicit manner across scales, with important implications for fire-related forest management and for constraining/benchmarking process models.

A landscape perspective for forest restoration

USGS Publications Warehouse

Sisk, Thomas D.; Savage, Melissa; Falk, Donald A.; Allen, Craig D.; Muldavin, Esteban; McCarthy, Patrick

2005-01-01

Forest managers throughout the West are anxiously seeking solutions to the problem of “large crown fires” - destructive blazes atypical of many forest types in the region. These wildfires have created a crisis mentality in management that has focused on rigid prescriptions for fuels reduction, rather than the restoration of diverse, resilient, and self-regulating forest ecosystems. Now, as we shape our responses to the threat of larger and more frequent crown fires, we are in danger of missing the forest for the trees.

Long-Term Effects of Season of Prescribed Burn on the Fine-Root Growth, Root Carbohydrates, and Foliar Dynamics of Mature Longleaf Pine

Treesearch

Eric A. Kuehler; Mary Anne Sword Sayer; James D. Haywood; C. Dan Andries

2004-01-01

Depending on the season and intensity of fire, as well as the phenology of foliage and new root growth, fire may damage foliage, and subsequently decrease whole-crown carbon fixation and allocation to the root system. In central Louisiana the authors investigated how season of prescribed burning affects fine-root dynamics, root carbohydrate relations, and leaf area...

Effects of season on ignition of live wildland fuels using the forced ignition and flame spread test apparatus

Treesearch

S. McAllister; D. R. Weise

2017-01-01

An understanding of what variables affect the ignition of live wildland fuels is crucial to predicting crown fire spread, the most poorly understood type of wildland fire. Ignition tests were performed over the course of an entire year for ten species (three species in year one, seven in year two) to evaluate seasonal changes in flammability. Ignition delay and mass...

Above-ground biomass and structure of pristine Siberian Scots pine forests as controlled by competition and fire.

PubMed

Wirth, C; Schulze, E-D; Schulze, W; von Stünzner-Karbe, D; Ziegler, W; Miljukova, I M; Sogatchev, A; Varlagin, A B; Panvyorov, M; Grigoriev, S; Kusnetzova, W; Siry, M; Hardes, G; Zimmermann, R; Vygodskaya, N N

1999-10-01

The study presents a data set of above-ground biomass (AGB), structure, spacing and fire regime, for 24 stands of pristine Siberian Scots pine (Pinus sylvestris) forests with lichens (n = 20) or Vaccinium/mosses (n = 4) as ground cover, along four chronosequences. The stands of the "lichen" site type (LT) were stratified into three chronosequences according to stand density and fire history. Allometric equations were established from 90 sample trees for stem, coarse branch, fine branch, twig and needle biomass. The LT stands exhibited a low but sustained biomass accumulation until a stand age of 383 years. AGB reached only 6-10 kg dw  m -2 after 200 years depending on stand density and fire history compared to 20 kg dw  m -2 in the "Vaccinium" type (VT) stands. Leaf area index (LAI) in the LT stands remained at 0.5-1.5 and crown cover was 30-60%, whereas LAI reached 2.5 and crown cover was >100% in the VT stands. Although nearest-neighbour analyses suggested the existence of density-dependent mortality, fire impact turned out to have a much stronger effect on density dynamics. Fire scar dating and calculation of mean and initial fire return intervals revealed that within the LT stands differences in structure and biomass were related to the severity of fire regimes, which in turn was related to the degree of landscape fragmentation by wetlands. Self-thinning analysis was used to define the local carrying capacity for biomass. A series of undisturbed LT stands was used to characterise the upper self-thinning boundary. Stands that had experienced a moderate fire regime were positioned well below the self-thinning boundary in a distinct fire-thinning band of reduced major axis regression slope -0.26. We discuss how this downward shift resulted from alternating phases of density reduction by fire and subsequent regrowth. We conclude that biomass in Siberian Scots pine forests is strongly influenced by fire and that climate change will affect ecosystem functions predominantly via changes in fire regimes.

The national Fire and Fire Surrogate study: Effects of fuel reduction methods on forest vegetation structure and fuels

USGS Publications Warehouse

Schwilk, D.W.; Keeley, J.E.; Knapp, E.E.; Mciver, J.; Bailey, J. D.; Fettig, C.J.; Fiedler, C.E.; Harrod, R.J.; Moghaddas, J.J.; Outcalt, K.W.; Skinner, C.N.; Stephens, S.L.; Waldrop, T.A.; Yaussy, D.A.; Youngblood, A.

2009-01-01

Changes in vegetation and fuels were evaluated from measurements taken before and after fuel reduction treatments (prescribed fire, mechanical treatments, and the combination of the two) at 12 Fire and Fire Surrogate (FFS) sites located in forests with a surface fire regime across the conterminous United States. To test the relative effectiveness of fuel reduction treatments and their effect on ecological parameters we used an informationtheoretic approach on a suite of 12 variables representing the overstory (basal area and live tree, sapling, and snag density), the understory (seedling density, shrub cover, and native and alien herbaceous species richness), and the most relevant fuel parameters for wildfire damage (height to live crown, total fuel bed mass, forest floor mass, and woody fuel mass). In the short term (one year after treatment), mechanical treatments were more effective at reducing overstory tree density and basal area and at increasing quadratic mean tree diameter. Prescribed fire treatments were more effective at creating snags, killing seedlings, elevating height to live crown, and reducing surface woody fuels. Overall, the response to fuel reduction treatments of the ecological variables presented in this paper was generally maximized by the combined mechanical plus burning treatment. If the management goal is to quickly produce stands with fewer and larger diameter trees, less surface fuel mass, and greater herbaceous species richness, the combined treatment gave the most desirable results. However, because mechanical plus burning treatments also favored alien species invasion at some sites, monitoring and control need to be part of the prescription when using this treatment. ?? 2009 by the Ecological Society of America.

Characterization of the humic substances isolated from postfire soils of scotch pine forest in Togljatty city, Samara region by the 13C-NMR spectroscopy

NASA Astrophysics Data System (ADS)

Maksimova, Ekaterina; Abakumov, Evgeny

2016-04-01

Postpyrogenic soil dynamics is an informative tool for studying of soil elementary processes in extreme temperature conditions and for predicting of short time environmental changes in conditions of catastrophic landscape changes. Soil organic matter (SOM) system evolution is the most rapid process of postpyrogenic soil development. In this relation the evaluation of humus accumulation rates and humification trend were conducted with use of the classical chemical and modern spectroscopy methods. Soil restoration after spontaneous forest fires near Togljatty city (Samara region, Russia) was abandoned in 2010, and further monitoring over the next four years was organized to evaluate the speed of biogenic processes and humus accumulation dynamics. Three key soil plots were studied for estimating SOM quality changes under the forest fire effect: surface forest fire, crown forest fire and control. Total carbon and nitrogen content as well as Cha/Cfa ratios (content of humic acids/ content of fulvic acids), were estimated to assess the dynamics of soil restoration. Humic acid powders were extracted and analyzed by elemental composition and 13C-NMR spectroscopy to assess changes in humic substance structure and composition. The data obtained indicate that burning of a forest floor and sod (humic) horizon led to humus losses and decreases in total carbon stocks. As a result of the fires, the content of humic acids in the pyrogenic horizon increased, leading alterations of humus type. Greater increases in the degree of organic matter humification were observed for surface fires than crown fires. It was shown that the humus molecular composition was substantially affected by the wildfires. The data show an increase in aromaticity, a loss of oxygen-containing groups and dehydrogenation of humic acids. Humic acids in the soils of the control plots and after wildfires were significantly different, especially in the ratios of hydrogen, oxygen and carbon. The increase in the degree of humic acid aromatization was confirmed by the hydrogen/carbon ratio. Investigation of the humic acids' molecular structure by 13C-NMR showed a relative increase in aromatic compounds and decrease in aliphatic ones. In general, crown and surface fires plots are not very different in terms of 13C-NMR spectra of humic acids, however humic acids of control plot have essential differences from pyrogenic ones. This study was a contribution to the Russian foundation for basic research, project for young scientists No.14-04-32132 and 15-34-20844.

Estimation of forest fuel load from radar remote sensing

USGS Publications Warehouse

Saatchi, S.; Halligan, K.; Despain, Don G.; Crabtree, R.L.

2007-01-01

Understanding fire behavior characteristics and planning for fire management require maps showing the distribution of wildfire fuel loads at medium to fine spatial resolution across large landscapes. Radar sensors from airborne or spaceborne platforms have the potential of providing quantitative information about the forest structure and biomass components that can be readily translated to meaningful fuel load estimates for fire management. In this paper, we used multifrequency polarimetric synthetic aperture radar (SAR) imagery acquired over a large area of the Yellowstone National Park by the Airborne SAR sensor to estimate the distribution of forest biomass and canopy fuel loads. Semiempirical algorithms were developed to estimate crown and stem biomass and three major fuel load parameters, namely: 1) canopy fuel weight; 2) canopy bulk density; and 3) foliage moisture content. These estimates, when compared directly to measurements made at plot and stand levels, provided more than 70% accuracy and, when partitioned into fuel load classes, provided more than 85% accuracy. Specifically, the radar-generated fuel parameters were in good agreement with the field-based fuel measurements, resulting in coefficients of determination of R2 = 85 for the canopy fuel weight, R 2 = 0.84 for canopy bulk density, and R2 =0.78 for the foliage biomass. ?? 2007 IEEE.

Little evidence for fire-adapted plant traits in Mediterranean climate regions.

PubMed

Bradshaw, S Don; Dixon, Kingsley W; Hopper, Stephen D; Lambers, Hans; Turner, Shane R

2011-02-01

As climate change increases vegetation combustibility, humans are impacted by wildfires through loss of lives and property, leading to an increased emphasis on prescribed burning practices to reduce hazards. A key and pervading concept accepted by most environmental managers is that combustible ecosystems have traditionally burnt because plants are fire adapted. In this opinion article, we explore the concept of plant traits adapted to fire in Mediterranean climates. In the light of major threats to biodiversity conservation, we recommend caution in deliberately increasing fire frequencies if ecosystem degradation and plant extinctions are to be averted as a result of the practice. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

Modelling the vertical distribution of canopy fuel load using national forest inventory and low-density airbone laser scanning data.

PubMed

González-Ferreiro, Eduardo; Arellano-Pérez, Stéfano; Castedo-Dorado, Fernando; Hevia, Andrea; Vega, José Antonio; Vega-Nieva, Daniel; Álvarez-González, Juan Gabriel; Ruiz-González, Ana Daría

2017-01-01

The fuel complex variables canopy bulk density and canopy base height are often used to predict crown fire initiation and spread. Direct measurement of these variables is impractical, and they are usually estimated indirectly by modelling. Recent advances in predicting crown fire behaviour require accurate estimates of the complete vertical distribution of canopy fuels. The objectives of the present study were to model the vertical profile of available canopy fuel in pine stands by using data from the Spanish national forest inventory plus low-density airborne laser scanning (ALS) metrics. In a first step, the vertical distribution of the canopy fuel load was modelled using the Weibull probability density function. In a second step, two different systems of models were fitted to estimate the canopy variables defining the vertical distributions; the first system related these variables to stand variables obtained in a field inventory, and the second system related the canopy variables to airborne laser scanning metrics. The models of each system were fitted simultaneously to compensate the effects of the inherent cross-model correlation between the canopy variables. Heteroscedasticity was also analyzed, but no correction in the fitting process was necessary. The estimated canopy fuel load profiles from field variables explained 84% and 86% of the variation in canopy fuel load for maritime pine and radiata pine respectively; whereas the estimated canopy fuel load profiles from ALS metrics explained 52% and 49% of the variation for the same species. The proposed models can be used to assess the effectiveness of different forest management alternatives for reducing crown fire hazard.

Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists

PubMed Central

Naumova, Ella A.; Schneider, Stephan; Arnold, Wolfgang H.; Piwowarczyk, Andree

2017-01-01

Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM) crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU)), a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE)) and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS)) were cemented on human molars. The crown and antagonists were subjected to simulated chewing. 3D data sets, before and after the chewing simulation, were generated and matched. Occlusal surface roughness, vertical and volume loss of the crowns and antagonists were analyzed. Results: Crown roughness was significantly different between the LU and VE groups after chewing simulation. Crown vertical loss differed in all groups. The highest crown volume loss was found in the LU group, and the lowest in the VE group. Comparisons between the LU and VE groups and the LU and VS groups were significantly different. The highest antagonist volume loss was reached in the VE group, the lowest was in the LU group. Conclusion: Roughness increased after chewing simulation. LU crowns are the most natural antagonist-friendly; these were the most susceptible to vertical and volume loss. Of the tested materials, the VE crowns are the most stable regarding occlusion. PMID:28772602

Space Radar Image of Yellowstone Park, Wyoming

NASA Technical Reports Server (NTRS)

1994-01-01

These two radar images show the majestic Yellowstone National Park, Wyoming, the oldest national park in the United States and home to the world's most spectacular geysers and hot springs. The region supports large populations of grizzly bears, elk and bison. In 1988, the park was burned by one of the most widespread fires to occur in the northern Rocky Mountains in the last 50 years. Surveys indicated that 793,880 acres of land burned. Of that, 41 percent was burned forest, with tree canopies totally consumed by the fire; 35 percent was a combination of unburned, scorched and blackened trees; 13 percent was surface burn under an unburned canopy; 6 percent was non-forest burn; and 5 percent was undifferentiated burn. Six years later, the burned areas are still clearly visible in these false-color radar images obtained by the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar on board the space shuttle Endeavour. The image at the left was obtained using the L-band radar channel, horizontally received and vertically transmitted, on the shuttle's 39th orbit on October 2, 1994. The area shown is 45 kilometers by 71 kilometers (28 miles by 44 miles) in size and centered at 44.6 degrees north latitude, 110.7 degrees west longitude. North is toward the top of the image (to the right). Most trees in this area are lodge pole pines at different stages of fire succession. Yellowstone Lake appears as a large dark feature at the bottom of the scene. At right is a map of the forest crown, showing its biomass, or amount of vegetation, which includes foliage and branches. The map was created by inverting SIR-C data and using in situ estimates of crown biomass gathered by the Yellowstone National Biological Survey. The map is displayed on a color scale from blue (rivers and lakes with no biomass) to brown (non-forest areas with crown biomass of less than 4 tons per hectare) to light brown (areas of canopy burn with biomass of between 4 and 12 tons per hectare). Yellow indicates areas of canopy burn and mixed burn with a biomass of between 12 to 20 tons per hectare; light green is mixed burn and on-burn forest with a biomass of 20 to 35 tons per hectare; and green is non-burned forest with a biomass of greater than 35 tons per hectare. Forest recovery from the fire seems to depend on fire intensity and soil conditions. In areas of severe canopy burn and poor soil conditions, crown biomass was still low in 1994 (indicated by the brown areas at the center left), whereas in areas of mixed burn with nutrient-rich soils, seen west of Yellowstone Lake, crown biomass has increased significantly in six years (indicated by the yellow and light green areas). Imaging fire-affected regions with spaceborne radar illustrates SIR-C/X-SAR's keen abilities to monitor regrowth after a fire. Knowing the amount of carbon accumulated in the atmosphere by regenerating forest in the 20 to 50 years following a fire disturbance is also a significant factor in understanding the global carbon cycle. Measuring crown biomass is necessary to evaluate the effects of past and future fires in specific regions. Spaceborne Imaging Radar-C and X-Synthetic Aperture Radar (SIR-C/X-SAR) are part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm), and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes that are caused by nature and those changes that are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.V.(DLR), the major partner in science, operations and data processing of X-SAR.

FireStem2D – A Two-Dimensional Heat Transfer Model for Simulating Tree Stem Injury in Fires

PubMed Central

Chatziefstratiou, Efthalia K.; Bohrer, Gil; Bova, Anthony S.; Subramanian, Ravishankar; Frasson, Renato P. M.; Scherzer, Amy; Butler, Bret W.; Dickinson, Matthew B.

2013-01-01

FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by resolving stem moisture loss, temperatures through the stem, degree of bark charring, and necrotic depth around the stem. We present the results of numerical parameterization and model evaluation experiments for FireStem2D that simulate laboratory stem-heating experiments of 52 tree sections from 25 trees. We also conducted a set of virtual sensitivity analysis experiments to test the effects of unevenness of heating around the stem and with aboveground height using data from two studies: a low-intensity surface fire and a more intense crown fire. The model allows for improved understanding and prediction of the effects of wildland fire on injury and mortality of trees of different species and sizes. PMID:23894599

Optimizing prescribed fire allocation for managing fire risk in central Catalonia.

PubMed

Alcasena, Fermín J; Ager, Alan A; Salis, Michele; Day, Michelle A; Vega-Garcia, Cristina

2018-04-15

We used spatial optimization to allocate and prioritize prescribed fire treatments in the fire-prone Bages County, central Catalonia (northeastern Spain). The goal of this study was to identify suitable strategic locations on forest lands for fuel treatments in order to: 1) disrupt major fire movements, 2) reduce ember emissions, and 3) reduce the likelihood of large fires burning into residential communities. We first modeled fire spread, hazard and exposure metrics under historical extreme fire weather conditions, including node influence grid for surface fire pathways, crown fraction burned and fire transmission to residential structures. Then, we performed an optimization analysis on individual planning areas to identify production possibility frontiers for addressing fire exposure and explore alternative prescribed fire treatment configurations. The results revealed strong trade-offs among different fire exposure metrics, showed treatment mosaics that optimize the allocation of prescribed fire, and identified specific opportunities to achieve multiple objectives. Our methods can contribute to improving the efficiency of prescribed fire treatment investments and wildfire management programs aimed at creating fire resilient ecosystems, facilitating safe and efficient fire suppression, and safeguarding rural communities from catastrophic wildfires. The analysis framework can be used to optimally allocate prescribed fire in other fire-prone areas within the Mediterranean region and elsewhere. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling the vertical distribution of canopy fuel load using national forest inventory and low-density airbone laser scanning data

PubMed Central

Castedo-Dorado, Fernando; Hevia, Andrea; Vega, José Antonio; Vega-Nieva, Daniel; Ruiz-González, Ana Daría

2017-01-01

The fuel complex variables canopy bulk density and canopy base height are often used to predict crown fire initiation and spread. Direct measurement of these variables is impractical, and they are usually estimated indirectly by modelling. Recent advances in predicting crown fire behaviour require accurate estimates of the complete vertical distribution of canopy fuels. The objectives of the present study were to model the vertical profile of available canopy fuel in pine stands by using data from the Spanish national forest inventory plus low-density airborne laser scanning (ALS) metrics. In a first step, the vertical distribution of the canopy fuel load was modelled using the Weibull probability density function. In a second step, two different systems of models were fitted to estimate the canopy variables defining the vertical distributions; the first system related these variables to stand variables obtained in a field inventory, and the second system related the canopy variables to airborne laser scanning metrics. The models of each system were fitted simultaneously to compensate the effects of the inherent cross-model correlation between the canopy variables. Heteroscedasticity was also analyzed, but no correction in the fitting process was necessary. The estimated canopy fuel load profiles from field variables explained 84% and 86% of the variation in canopy fuel load for maritime pine and radiata pine respectively; whereas the estimated canopy fuel load profiles from ALS metrics explained 52% and 49% of the variation for the same species. The proposed models can be used to assess the effectiveness of different forest management alternatives for reducing crown fire hazard. PMID:28448524

Biomechanical validation of an artificial tooth–periodontal ligament–bone complex for in vitro orthodontic load measurement

PubMed Central

Xia, Zeyang; Chen, Jie

2014-01-01

Objectives To develop an artificial tooth–periodontal ligament (PDL)–bone complex (ATPBC) that simulates clinical crown displacement. Material and Methods An ATPBC was created. It had a socket hosting a tooth with a thin layer of silicon mixture in between for simulating the PDL. The complex was attached to a device that allows applying a controlled force to the crown and measuring the resulting crown displacement. Crown displacements were compared to previously published data for validation. Results The ATPBC that had a PDL made of two types of silicones, 50% gasket sealant No. 2 and 50% RTV 587 silicone, with a thickness of 0.3 mm, simulated the PDL well. The mechanical behaviors (1) force-displacement relationship, (2) stress relaxation, (3) creep, and (4) hysteresis were validated by the published results. Conclusion The ATPBC simulated the crown displacement behavior reported from biological studies well. PMID:22970752

Fire Behavior (FB)

Treesearch

Robert E. Keane

2006-01-01

The Fire Behavior (FB) method is used to describe the behavior of the fire and the ambient weather and fuel conditions that influence the fire behavior. Fire behavior methods are not plot based and are collected by fire event and time-date. In general, the fire behavior data are used to interpret the fire effects documented in the plot-level sampling. Unlike the other...

Micromorphological characteristics of sandy forest soils recently impacted by wildfires in Russia

NASA Astrophysics Data System (ADS)

Maksimova, Ekaterina; Abakumov, Evgeny

2017-04-01

Two fire-affected soils were studied using micromorphological methods. The objective of the paper is to assess and compare fire effects on the micropedological organisation of soils in a forest-steppe zone of central Russia (Volga Basin, Togliatti city). Samples were collected in the green zone of Togliatti city. The results showed that both soils were rich in quartz and feldspar. Mica was highly present in soils affected by surface fires, while calcium carbonates were identified in the soils affected by crown fires. The type of plasma is humus-clay, but the soil assemblage is plasma-silt with a prevalence of silt. Angular and subangular grains are the most dominant soil particulates. No evidence of intensive weathering was detected. There was a decrease in the porosity of soils affected by fires as a consequence of soil pores filled with ash and charcoal.

Ecological effects of large fires on US landscapes: benefit or catastrophe?

USGS Publications Warehouse

Keane, Robert E.; Agee, James K.; Fule, Peter; Keeley, Jon E.; Key, Carl H.; Kitchen, Stanley G.; Miller, Richard; Schulte, Lisa A.

2008-01-01

The perception is that today’s large fires are an ecological catastrophe because they burn vast areas with high intensities and severities. However, little is known of the ecological impacts of large fires on both historical and contemporary landscapes. The present paper presents a review of the current knowledge of the effects of large fires in the United States by important ecosystems written by regional experts. The ecosystems are (1) ponderosa pine–Douglas-fir, (2) sagebrush–grasslands, (3) piñon–juniper, (4) chaparral, (5) mixed-conifer, and (6) spruce–fir. This review found that large fires were common on most historical western US landscapes and they will continue to be common today with exceptions. Sagebrush ecosystems are currently experiencing larger, more severe, and more frequent large fires compared to historical conditions due to exotic cheatgrass invasions. Historical large fires in south-west ponderosa pine forest created a mixed severity mosaic dominated by non-lethal surface fires while today’s large fires are mostly high severity crown fires. While large fires play an important role in landscape ecology for most regions, their importance is much less in the dry piñon–juniper forests and sagebrush–grasslands. Fire management must address the role of large fires in maintaining the health of many US fire-dominated ecosystems.

Examining the relative effects of fire weather, suppression and fuel treatment on fire behaviour--a simulation study.

PubMed

Penman, T D; Collins, L; Price, O F; Bradstock, R A; Metcalf, S; Chong, D M O

2013-12-15

Large budgets are spent on both suppression and fuel treatments in order to reduce the risk of wildfires. There is little evidence regarding the relative contribution of fire weather, suppression and fuel treatments in determining the risk posed from wildfires. Here we undertake a simulation study in the Sydney Basin, Australia, to examine this question using a fire behaviour model (Phoenix Rapidfire). Results of the study indicate that fire behaviour is most strongly influenced by fire weather. Suppression has a greater influence on whether a fire reaches 5 ha in size compared to fuel treatments. In contrast, fuel treatments have a stronger effect on the fire size and maximum distance the fire travels. The study suggests that fire management agencies will receive additional benefits from fuel treatment if they are located in areas which suppression resources can respond rapidly and attempt to contain the fires. No combination of treatments contained all fires, and the proportion of uncontained fires increased under more severe fire weather when the greatest number of properties are lost. Our study highlights the importance of alternative management strategies to reduce the risk of property loss. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Feeding behavior and diet of free ranging black crowned night herons on a catfish aquaculture facility in Mississippi

USDA-ARS?s Scientific Manuscript database

The impacts of many species of piscivorous birds on aquaculture are well documented in the southeastern United States; however, specific studies of black-crowned night heron (Nycticorax nycticorax) in these areas are lacking. It was observed that black-crowned night herons opportunistically exploit ...

Hard Evidence for Melaleuca Biocontrol

USDA-ARS?s Scientific Manuscript database

The population dynamics of a cohort of Melaleuca quinquenervia were monitored over a 5-y period in a cypress-pine wetland while subjected to two levels of herbivory. The trees were recruited during 1998-1999 after a destructive crown fire. Half of 26 experimental plots were sprayed every 4-6 weeks...

Restoring productivity to cogograss-infested land through reforestation

Treesearch

W.H. Faircloth; M.G. Patterson; James H. Miller; D.H. Teem

2004-01-01

Cogongrass (Imperata cylindrica) is an invasive grass that is rapidly colonizing the Gulf coastal plain, with potential to spread well into the interior of the Southeastern U.S. Cogongrass is particularly harmful to forested land. In such situations, cogongrass hinders plantation establishment, may contribute to crowning fires in young stands,...

Effects of ecosystem-based management treatments

Treesearch

Michael G. Harrington; Carl E. Fiedler; Stephen F. Arno; Ward W. McCaughey; Leon J. Theroux; Clinton E. Carlson; Kristin L. Zouhar; Thomas H. DeLuca; Donald J. Bedunah; Dayna M. Ayers; Elizabeth A. Beringer; Sallie J. Hejl; Lynn Bacon; Robert E. Benson; Jane Kapler Smith; Rick Floch

1999-01-01

The prescribed burn treatments were applied to reduce pre-existing and new slash fuel loadings, reduce understory tree density to lower crown fire potential, stimulate vigor of decadent understory vegetation, produce mineral seedbeds for seral species establishment, and increase availability of mineral nutrients. To test the feasibility of prescribed burning under a...

Estimation of wildfire size and risk changes due to fuels treatments

USGS Publications Warehouse

Cochrane, M.A.; Moran, C.J.; Wimberly, M.C.; Baer, A.D.; Finney, M.A.; Beckendorf, K.L.; Eidenshink, J.; Zhu, Z.

2012-01-01

Human land use practices, altered climates, and shifting forest and fire management policies have increased the frequency of large wildfires several-fold. Mitigation of potential fire behaviour and fire severity have increasingly been attempted through pre-fire alteration of wildland fuels using mechanical treatments and prescribed fires. Despite annual treatment of more than a million hectares of land, quantitative assessments of the effectiveness of existing fuel treatments at reducing the size of actual wildfires or how they might alter the risk of burning across landscapes are currently lacking. Here, we present a method for estimating spatial probabilities of burning as a function of extant fuels treatments for any wildland fire-affected landscape. We examined the landscape effects of more than 72 000 ha of wildland fuel treatments involved in 14 large wildfires that burned 314 000 ha of forests in nine US states between 2002 and 2010. Fuels treatments altered the probability of fire occurrence both positively and negatively across landscapes, effectively redistributing fire risk by changing surface fire spread rates and reducing the likelihood of crowning behaviour. Trade offs are created between formation of large areas with low probabilities of increased burning and smaller, well-defined regions with reduced fire risk.

Retrospective Study of Retention of Stainless Steel Crowns and Pre-veneered Crowns on Primary Anterior Teeth.

PubMed

Lopez-Loverich, Angela M; Garcia, Maria Minerva; Donly, Kevin J

2015-01-01

The purpose of this retrospective chart review was to explore the retention of anterior pre-veneered stainless steel crowns (NuSmile) and conventional stainless steel crowns (3M ESPE) placed on primary anterior teeth. Records for children were reviewed over four years using the electronic record system axiUm. Data collected included child's age at time of crown placement, date of placement, tooth number, type of crown, patient behavior, treatment environment, provider type, crown presence, absence, and cementation success or failure at subsequent recall visits. A total of 637 anterior crowns in children treated with either or both crown types met this study's inclusion criteria. Of these crowns, 483 were NuSmile Signature crowns and 154 were stainless steel crowns. There was a nine percent failure rate for the NuSmile Signature crowns and a seven percent failure rate for the stainless steel crowns. There was no statistically significant difference in crown retention rates between the two groups (P<0.05). A full-coverage restoration that can follow the lifespan of the primary anterior dentition in high-risk children is needed. The results from this study indicate good crown retention rates for both crown types with no statistically significant difference between them (P<0.05).

Using Airborne LIDAR Data for Assessment of Forest Fire Fuel Load Potential

NASA Astrophysics Data System (ADS)

İnan, M.; Bilici, E.; Akay, A. E.

2017-11-01

Forest fire incidences are one of the most detrimental disasters that may cause long terms effects on forest ecosystems in many parts of the world. In order to minimize environmental damages of fires on forest ecosystems, the forested areas with high fire risk should be determined so that necessary precaution measurements can be implemented in those areas. Assessment of forest fire fuel load can be used to estimate forest fire risk. In order to estimate fuel load capacity, forestry parameters such as number of trees, tree height, tree diameter, crown diameter, and tree volume should be accurately measured. In recent years, with the advancements in remote sensing technology, it is possible to use airborne LIDAR for data estimation of forestry parameters. In this study, the capabilities of using LIDAR based point cloud data for assessment of the forest fuel load potential was investigated. The research area was chosen in the Istanbul Bentler series of Bahceköy Forest Enterprise Directorate that composed of mixed deciduous forest structure.

Preliminary results of fire behavior in maquis fuels under varying weather and slope conditions in turkey

Treesearch

Bulent Saglam; Ertugrul Bilgili; Omer Kucuk; Bahar Dinc Durmaz; Ismail Baysal

2007-01-01

The prediction of fire behavior is of vital importance to all fire management planning and decisionmaking processes including fire prevention, presuppression planning, and fire use. The effect of slope on fire behavior is well acknowledged, yet its effect on fire behavior is not well accounted for. Determining the effects of slope on fire behavior under field...

Potential climate change impacts on fire intensity and key wildfire suppression thresholds in Canada

NASA Astrophysics Data System (ADS)

Wotton, B. M.; Flannigan, M. D.; Marshall, G. A.

2017-09-01

Much research has been carried out on the potential impacts of climate change on forest fire activity in the boreal forest. Indeed, there is a general consensus that, while change will vary regionally across the vast extent of the boreal, in general the fire environment will become more conducive to fire. Land management agencies must consider ways to adapt to these new conditions. This paper examines the impact of that changed fire environment on overall wildfire suppression capability. We use multiple General Circulation Models and carbon emission pathways to generate future fire environment scenarios for Canada’s forested region. We then use these scenarios with the Canadian Forest Fire Behaviour Prediction System and spatial coverages of the current forest fuel composition across the landscape to examine potential variation in key fire behaviour outputs that influence whether fire management resources can effectively suppress fire. Specifically, we evaluate how the potential for crown fire occurrence and active growth of fires changes with the changing climate. We also examine future fire behaviour through the lens of operational fire intensity thresholds used to guide decisions about resources effectiveness. Results indicate that the proportion of days in fire seasons with the potential for unmanageable fire will increase across Canada’s forest, more than doubling in some regions in northern and eastern boreal forest.

Late Holocene geomorphic record of fire in ponderosa pine and mixed-conifer forests, Kendrick Mountain, northern Arizona, USA

USGS Publications Warehouse

Jenkins, S.E.; Hull, Sieg C.; Anderson, D.E.; Kaufman, D.S.; Pearthree, P.A.

2011-01-01

Long-term fire history reconstructions enhance our understanding of fire behaviour and associated geomorphic hazards in forested ecosystems. We used 14C ages on charcoal from fire-induced debris-flow deposits to date prehistoric fires on Kendrick Mountain, northern Arizona, USA. Fire-related debris-flow sedimentation dominates Holocene fan deposition in the study area. Radiocarbon ages indicate that stand-replacing fire has been an important phenomenon in late Holocene ponderosa pine (Pinus ponderosa) and ponderosa pine-mixed conifer forests on steep slopes. Fires have occurred on centennial scales during this period, although temporal hiatuses between recorded fires vary widely and appear to have decreased during the past 2000 years. Steep slopes and complex terrain may be responsible for localised crown fire behaviour through preheating by vertical fuel arrangement and accumulation of excessive fuels. Holocene wildfire-induced debris flow events occurred without a clear relationship to regional climatic shifts (decadal to millennial), suggesting that interannual moisture variability may determine fire year. Fire-debris flow sequences are recorded when (1) sufficient time has passed (centuries) to accumulate fuels; and (2) stored sediment is available to support debris flows. The frequency of reconstructed debris flows should be considered a minimum for severe events in the study area, as fuel production may outpace sediment storage. ?? IAWF 2011.

Biological and geophysical feedbacks with fire in the Earth system

NASA Astrophysics Data System (ADS)

Archibald, S.; Lehmann, C. E. R.; Belcher, C. M.; Bond, W. J.; Bradstock, R. A.; Daniau, A.-L.; Dexter, K. G.; Forrestel, E. J.; Greve, M.; He, T.; Higgins, S. I.; Hoffmann, W. A.; Lamont, B. B.; McGlinn, D. J.; Moncrieff, G. R.; Osborne, C. P.; Pausas, J. G.; Price, O.; Ripley, B. S.; Rogers, B. M.; Schwilk, D. W.; Simon, M. F.; Turetsky, M. R.; Van der Werf, G. R.; Zanne, A. E.

2018-03-01

Roughly 3% of the Earth’s land surface burns annually, representing a critical exchange of energy and matter between the land and atmosphere via combustion. Fires range from slow smouldering peat fires, to low-intensity surface fires, to intense crown fires, depending on vegetation structure, fuel moisture, prevailing climate, and weather conditions. While the links between biogeochemistry, climate and fire are widely studied within Earth system science, these relationships are also mediated by fuels—namely plants and their litter—that are the product of evolutionary and ecological processes. Fire is a powerful selective force and, over their evolutionary history, plants have evolved traits that both tolerate and promote fire numerous times and across diverse clades. Here we outline a conceptual framework of how plant traits determine the flammability of ecosystems and interact with climate and weather to influence fire regimes. We explore how these evolutionary and ecological processes scale to impact biogeochemical and Earth system processes. Finally, we outline several research challenges that, when resolved, will improve our understanding of the role of plant evolution in mediating the fire feedbacks driving Earth system processes. Understanding current patterns of fire and vegetation, as well as patterns of fire over geological time, requires research that incorporates evolutionary biology, ecology, biogeography, and the biogeosciences.

Fire in the west: It's no simple story

USGS Publications Warehouse

Betancourt, Julio L.; Swetnam, Thomas W.; Allen, Craig D.; Savage, Melissa

2003-01-01

As scientists who have long grappled with the complexities of fire history in the West, we take issue with Ray Ring’s overreaching storyline that the recent spate of stand-replacing forest fires reflects wholly natural processes operating across all Western landscapes (HCN, 5/26/03: A losing battle). Ring further asserts that the main driver of recent crown fires must be climatic change, and not the extraordinary fuel accumulations of the 20th century. If we want to cope with huge wildfires over the long term, Ring concludes, we should focus less on thinning our forests and more on cutting greenhouse gas emissions to curtail global warming. We appreciate that Ring’s simple storyline was meant to be provocative. We insist, however, that the circumstances driving Western wildfires are actually quite varied and complex, involving interactions between climate and fuels.

Tree mortality following prescribed fire and a storm surge event in Slash Pine (pinus elliottii var. densa) forests in the Florida Keys, USA

USGS Publications Warehouse

Sah, Jay P.; Ross, Michael S.; Snyder, James R.; Ogurcak, Danielle E.

2010-01-01

In fire-dependent forests, managers are interested in predicting the consequences of prescribed burning on postfire tree mortality. We examined the effects of prescribed fire on tree mortality in Florida Keys pine forests, using a factorial design with understory type, season, and year of burn as factors. We also used logistic regression to model the effects of burn season, fire severity, and tree dimensions on individual tree mortality. Despite limited statistical power due to problems in carrying out the full suite of planned experimental burns, associations with tree and fire variables were observed. Post-fire pine tree mortality was negatively correlated with tree size and positively correlated with char height and percent crown scorch. Unlike post-fire mortality, tree mortality associated with storm surge from Hurricane Wilma was greater in the large size classes. Due to their influence on population structure and fuel dynamics, the size-selective mortality patterns following fire and storm surge have practical importance for using fire as a management tool in Florida Keys pinelands in the future, particularly when the threats to their continued existence from tropical storms and sea level rise are expected to increase.

A numerical solution of the problem of crown forest fire initiation and spread

NASA Astrophysics Data System (ADS)

Marzaeva, S. I.; Galtseva, O. V.

2018-05-01

Mathematical model of forest fire was based on an analysis of known experimental data and using concept and methods from reactive media mechanics. The study takes in to account the mutual interaction of the forest fires and three-dimensional atmosphere flows. The research is done by means of mathematical modeling of physical processes. It is based on numerical solution of Reynolds equations for chemical components and equations of energy conservation for gaseous and condensed phases. It is assumed that the forest during a forest fire can be modeled as a two-temperature multiphase non-deformable porous reactive medium. A discrete analog for the system of equations was obtained by means of the control volume method. The developed model of forest fire initiation and spreading would make it possible to obtain a detailed picture of the variation in the velocity, temperature and chemical species concentration fields with time. Mathematical model and the result of the calculation give an opportunity to evaluate critical conditions of the forest fire initiation and spread which allows applying the given model for of means for preventing fires.

Fire behavior, fuel treatments, and fire suppression on the Hayman Fire - Part 2: Description and interpretations of fire behavior

Treesearch

Mark A. Finney; Charles W. McHugh; Roberta Bartlette; Kelly Close; Paul Langowski

2003-01-01

This report summarizes the progress of the Hayman Fire, its behavior, and the influence of environmental conditions. Data were obtained from narratives from fire behavior analysts assigned to the fire management teams, discussions with fire management staff, meteorology from local weather stations and Bradshaw and others (2003), photographs, satellite imagery, and...

State of Fire Behavior Models and their Application to Ecosystem and Smoke Management Issues: Special Session Summary Report

DTIC Science & Technology

2013-10-24

advance fire science: (1) fire behavior, (2) ecological effects of fire, (3) carbon accounting , (4) emissions characterization, and (5) fire plume...relates to smoke management. 3) Carbon accounting in forest management and prescribed fire programs (including tradeoffs such as prescribed burning...carbon accounting , 4) emissions characterization and 5) fire plume dispersion. 1) Fire behavior. Better characterization of wildland fire behavior is

Integrating stand density management with fuel reduction

Treesearch

Joseph W. Sherlock

2007-01-01

The widespread effort to reduce fuel hazards in western forested ecosystems places significant emphasis on surface and small ladder fuels. Changes in canopy density, for purposes of either reducing potential crown fire impacts or insect/pathogen-related mortality, are less frequently considered. Providing a sound basis for treating more than surface and small ladder...

Best predictors for postfire mortality of ponderosa pine trees in the Intermountain West

Treesearch

Carolyn Hull Sieg; Joel D. McMillin; James F. Fowler; Kurt K. Allen; Jose F. Negron; Linda L. Wadleigh; John A. Anhold; Ken E. Gibson

2006-01-01

Numerous wildfires in recent years have highlighted managers' needs for reliable tools to predict postfire mortality of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) trees. General applicability of existing mortality models is uncertain, as researchers have used different sets of variables. We quantified tree attributes, crown and bole fire...

Forestry timber typing. Tanana demonstration project, Alaska ASVT. [Alaska

NASA Technical Reports Server (NTRS)

Morrissey, L. A.; Ambrosia, V. G.

1982-01-01

The feasibility of using LANDSAT digital data in conjunction with topographic data to delineate commercial forests by stand size and crown closure in the Tanana River basin of Alaska was tested. A modified clustering approach using two LANDSAT dates to generate an initial forest type classification was then refined with topographic data. To further demonstrate the ability of remotely sensed data in a fire protection planning framework, the timber type data were subsequently integrated with terrain information to generate a fire hazard map of the study area. This map provides valuable assistance in initial attack planning, determining equipment accessibility, and fire growth modeling. The resulting data sets were incorporated into the Alaska Department of Natural Resources geographic information system for subsequent utilization.

[Effects of fire recurrence on fire behaviour in cork oak woodlands (Quercus suber L.) and Mediterranean shrublands over the last fifty years].

PubMed

Schaffhauser, Alice; Pimont, François; Curt, Thomas; Cassagne, Nathalie; Dupuy, Jean-Luc; Tatoni, Thierry

2015-12-01

Past fire recurrence impacts the vegetation structure, and it is consequently hypothesized to alter its future fire behaviour. We examined the fire behaviour in shrubland-forest mosaics of southeastern France, which were organized along a range of fire frequency (0 to 3-4 fires along the past 50 years) and had different time intervals between fires. The mosaic was dominated by Quercus suber L. and Erica-Cistus shrubland communities. We described the vegetation structure through measurements of tree height, base of tree crown or shrub layer, mean diameter, cover, plant water content and bulk density. We used the physical model Firetec to simulate the fire behaviour. Fire intensity, fire spread, plant water content and biomass loss varied significantly according to fire recurrence and vegetation structure, mainly linked to the time since the last fire, then the number of fires. These results confirm that past fire recurrence affects future fire behaviour, with multi-layered vegetation (particularly high shrublands) producing more intense fires, contrary to submature Quercus woodlands that have not burnt since 1959 and that are unlikely to reburn. Further simulations, with more vegetation scenes according to shrub and canopy covers, will complete this study in order to discuss the fire propagation risk in heterogeneous vegetation, particularly in the Mediterranean area, with a view to a local management of these ecosystems. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

Numerical investigation of aggregated fuel spatial pattern impacts on fire behavior

DOE PAGES

Parsons, Russell A.; Linn, Rodman Ray; Pimont, Francois; ...

2017-06-18

Here, landscape heterogeneity shapes species distributions, interactions, and fluctuations. Historically, in dry forest ecosystems, low canopy cover and heterogeneous fuel patterns often moderated disturbances like fire. Over the last century, however, increases in canopy cover and more homogeneous patterns have contributed to altered fire regimes with higher fire severity. Fire management strategies emphasize increasing within-stand heterogeneity with aggregated fuel patterns to alter potential fire behavior. Yet, little is known about how such patterns may affect fire behavior, or how sensitive fire behavior changes from fuel patterns are to winds and canopy cover. Here, we used a physics-based fire behavior model,more » FIRETEC, to explore the impacts of spatially aggregated fuel patterns on the mean and variability of stand-level fire behavior, and to test sensitivity of these effects to wind and canopy cover. Qualitative and quantitative approaches suggest that spatial fuel patterns can significantly affect fire behavior. Based on our results we propose three hypotheses: (1) aggregated spatial fuel patterns primarily affect fire behavior by increasing variability; (2) this variability should increase with spatial scale of aggregation; and (3) fire behavior sensitivity to spatial pattern effects should be more pronounced under moderate wind and fuel conditions.« less

Numerical investigation of aggregated fuel spatial pattern impacts on fire behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons, Russell A.; Linn, Rodman Ray; Pimont, Francois

Here, landscape heterogeneity shapes species distributions, interactions, and fluctuations. Historically, in dry forest ecosystems, low canopy cover and heterogeneous fuel patterns often moderated disturbances like fire. Over the last century, however, increases in canopy cover and more homogeneous patterns have contributed to altered fire regimes with higher fire severity. Fire management strategies emphasize increasing within-stand heterogeneity with aggregated fuel patterns to alter potential fire behavior. Yet, little is known about how such patterns may affect fire behavior, or how sensitive fire behavior changes from fuel patterns are to winds and canopy cover. Here, we used a physics-based fire behavior model,more » FIRETEC, to explore the impacts of spatially aggregated fuel patterns on the mean and variability of stand-level fire behavior, and to test sensitivity of these effects to wind and canopy cover. Qualitative and quantitative approaches suggest that spatial fuel patterns can significantly affect fire behavior. Based on our results we propose three hypotheses: (1) aggregated spatial fuel patterns primarily affect fire behavior by increasing variability; (2) this variability should increase with spatial scale of aggregation; and (3) fire behavior sensitivity to spatial pattern effects should be more pronounced under moderate wind and fuel conditions.« less

Defining pyromes and global syndromes of fire regimes.

PubMed

Archibald, Sally; Lehmann, Caroline E R; Gómez-Dans, Jose L; Bradstock, Ross A

2013-04-16

Fire is a ubiquitous component of the Earth system that is poorly understood. To date, a global-scale understanding of fire is largely limited to the annual extent of burning as detected by satellites. This is problematic because fire is multidimensional, and focus on a single metric belies its complexity and importance within the Earth system. To address this, we identified five key characteristics of fire regimes--size, frequency, intensity, season, and extent--and combined new and existing global datasets to represent each. We assessed how these global fire regime characteristics are related to patterns of climate, vegetation (biomes), and human activity. Cross-correlations demonstrate that only certain combinations of fire characteristics are possible, reflecting fundamental constraints in the types of fire regimes that can exist. A Bayesian clustering algorithm identified five global syndromes of fire regimes, or pyromes. Four pyromes represent distinctions between crown, litter, and grass-fueled fires, and the relationship of these to biomes and climate are not deterministic. Pyromes were partially discriminated on the basis of available moisture and rainfall seasonality. Human impacts also affected pyromes and are globally apparent as the driver of a fifth and unique pyrome that represents human-engineered modifications to fire characteristics. Differing biomes and climates may be represented within the same pyrome, implying that pathways of change in future fire regimes in response to changes in climate and human activity may be difficult to predict.

Defining pyromes and global syndromes of fire regimes

PubMed Central

Archibald, Sally; Lehmann, Caroline E. R.; Gómez-Dans, Jose L.; Bradstock, Ross A.

2013-01-01

Fire is a ubiquitous component of the Earth system that is poorly understood. To date, a global-scale understanding of fire is largely limited to the annual extent of burning as detected by satellites. This is problematic because fire is multidimensional, and focus on a single metric belies its complexity and importance within the Earth system. To address this, we identified five key characteristics of fire regimes—size, frequency, intensity, season, and extent—and combined new and existing global datasets to represent each. We assessed how these global fire regime characteristics are related to patterns of climate, vegetation (biomes), and human activity. Cross-correlations demonstrate that only certain combinations of fire characteristics are possible, reflecting fundamental constraints in the types of fire regimes that can exist. A Bayesian clustering algorithm identified five global syndromes of fire regimes, or pyromes. Four pyromes represent distinctions between crown, litter, and grass-fueled fires, and the relationship of these to biomes and climate are not deterministic. Pyromes were partially discriminated on the basis of available moisture and rainfall seasonality. Human impacts also affected pyromes and are globally apparent as the driver of a fifth and unique pyrome that represents human-engineered modifications to fire characteristics. Differing biomes and climates may be represented within the same pyrome, implying that pathways of change in future fire regimes in response to changes in climate and human activity may be difficult to predict. PMID:23559374

Primary incisor restoration using resin-veneered stainless steel crowns.

PubMed

Croll, T P

1998-01-01

The restoration of primary incisors with extensive caries lesions is a clinical challenge of severe dimensions. Not only are these teeth difficult to restore, but the patient's behavior can affect the treatment negatively. Requirements for an acceptable restoration include natural color; durability; adhesive cementation that is biocompatible with the pulp; easily and rapidly placed; requires only one treatment visit. Compared to other options, stainless steel crowns are the easiest to place. The most attractive restoration for these cases today is the adhesively bonded resin-composite crown, made by using acetate crown-form matrices, but this is being surpassed by the stainless steel crown forms (3M Unitek) that can be preveneered. This article describes a step-by-step method of placing preveneered stainless steel crowns for primary incisors.

From open to closed canopy: A century of change in Douglas-fir forest, Orcas Island, Washington

USGS Publications Warehouse

Peterson, D.L.; Hammer, R.D.

2001-01-01

During the past century, forest structure on south-facing slopes of Mount Constitution, Orcas Island, Washington, has changed from open-grown Douglas-fir (Pseudotsuga menziesii) mixed with prairie to primarily closed canopy forest. Density of open-grown Douglas-fir was approximately 7 stems/ha in the 19th century, while current density of trees in closed-canopy mature forest is 426 stems/ha. Trees occur at intermediate densities in areas of transition from savanna-like stands to closed canopy. Analysis of fire scars indicates that at least seven fires have occurred on Mount Constitution since 1736, but only one fire has occurred since 1893, which suggests that the recent increase in stem density has been caused primarily by fire exclusion. The high stem densities currently found in this landscape put the relict (120-350+ years old) Douglas-fir at risk from contemporary fires, which would likely be high-intensity crown fires. Given the transition of forests on Orcas Island during the 20th century to closed canopy structure, undisturbed open-grown coniferous forest is now extremely rare in the San Juan Islands.

A comparison of charcoal measurements for reconstruction of Mediterranean paleo-fire frequency in the mountains of Corsica

NASA Astrophysics Data System (ADS)

Leys, Bérangère; Carcaillet, Christopher; Dezileau, Laurent; Ali, Adam A.; Bradshaw, Richard H. W.

2013-05-01

Fire-history reconstructions inferred from sedimentary charcoal records are based on measuring sieved charcoal fragment area, estimating fragment volume, or counting fragments. Similar fire histories are reconstructed from these three approaches for boreal lake sediment cores, using locally defined thresholds. Here, we test the same approach for a montane Mediterranean lake in which taphonomical processes might differ from boreal lakes through fragmentation of charcoal particles. The Mediterranean charcoal series are characterized by highly variable charcoal accumulation rates. Results there indicate that the three proxies do not provide comparable fire histories. The differences are attributable to charcoal fragmentation. This could be linked to fire type (crown or surface fires) or taphonomical processes, including charcoal transportation in the catchment area or in the sediment. The lack of correlation between the concentration of charcoal and of mineral matter suggests that fragmentation is not linked to erosion. Reconstructions based on charcoal area are more robust and stable than those based on fragment counts. Area-based reconstructions should therefore be used instead of the particle-counting method when fragmentation may influence the fragment abundance.

Under-burning and dwarf mistletoe: Scorch 'n' toe

Treesearch

David A. Conklin; Brian W. Geils

2008-01-01

Relatively little quantitative information has been available on the effects of low-intensity fire (under-burning) on dwarf mistletoe. Here we summarize results from six operational prescribed under-burns in second-growth ponderosa pine in New Mexico (Conklin and Geils, in press). For 1585 trees on 14 plots, crown scorch, bole char, and DMR were significant predictors...

FUEL3-D: A Spatially Explicit Fractal Fuel Distribution Model

Treesearch

Russell A. Parsons

2006-01-01

Efforts to quantitatively evaluate the effectiveness of fuels treatments are hampered by inconsistencies between the spatial scale at which fuel treatments are implemented and the spatial scale, and detail, with which we model fire and fuel interactions. Central to this scale inconsistency is the resolution at which variability within the fuel bed is considered. Crown...

Preparation Ferrule Design Effect on EndoCrown Fracture Resistance

DTIC Science & Technology

2016-05-01

Resistance Major Michael L. Einhorn APPROVED: Dean, Air Force Postgraduate Dental School II Acknowledgements: Special thanks to Col Howard Roberts...permission of the copyright owner. Signature Printed Name USAF Postgraduate Dental School Keesler AFB, MS Uniformed Services University -iv...Glaze spray, lvoclar-Vivadent) were applied with crystallization firing accomplished following manufacturer recommendations in a dental laboratory

Quantifying Ladder Fuels: A New Approach Using LiDAR

Treesearch

Heather Kramer; Brandon Collins; Maggi Kelly; Scott Stephens

2014-01-01

We investigated the relationship between LiDAR and ladder fuels in the northern Sierra Nevada, California USA. Ladder fuels are often targeted in hazardous fuel reduction treatments due to their role in propagating fire from the forest floor to tree crowns. Despite their importance, ladder fuels are difficult to quantify. One common approach is to calculate canopy base...

Tree Mortality following Prescribed Fire and a Storm Surge Event in Slash Pine ( Pinus elliottii var. densa ) Forests in the Florida Keys, USA

DOE PAGES

Sah, Jay P.; Ross, Michael S.; Snyder, James R.; ...

2010-01-01

In fire-dependent forests, managers are interested in predicting the consequences of prescribed burning on postfire tree mortality. We examined the effects of prescribed fire on tree mortality in Florida Keys pine forests, using a factorial design with understory type, season, and year of burn as factors. We also used logistic regression to model the effects of burn season, fire severity, and tree dimensions on individual tree mortality. Despite limited statistical power due to problems in carrying out the full suite of planned experimental burns, associations with tree and fire variables were observed. Post-fire pine tree mortality was negatively correlated withmore » tree size and positively correlated with char height and percent crown scorch. Unlike post-fire mortality, tree mortality associated with storm surge from Hurricane Wilma was greater in the large size classes. Due to their influence on population structure and fuel dynamics, the size-selective mortality patterns following fire and storm surge have practical importance for using fire as a management tool in Florida Keys pinelands in the future, particularly when the threats to their continued existence from tropical storms and sea level rise are expected to increase.« less

Forest fire effects on transpiration: process modeling of sapwood area reduction

NASA Astrophysics Data System (ADS)

Michaletz, Sean; Johnson, Edward

2010-05-01

Transpiration is a hydrological process that is strongly affected by forest fires. In crown fires, canopy fine fuels (foliage, buds, and small branches) combust, which kills individual trees and stops transpiration of the entire stand. In surface fires (intensities ≤ 2500 kW m-1), however, effects on transpiration are less predictable becuase heat transfer from the passing fireline can injure or kill fine roots, leaves, and sapwood; post-fire transpiration of forest stands is thus governed by fire effects on individual tree water budgets. Here, we consider fire effects on cross-sectional sapwood area. A two-dimensional model of transient bole heating is used to estimate radial isotherms for a range of fireline intensities typical of surface fires. Isotherms are then used to drive three processes by which heat may reduce sapwood area: 1) necrosis of living cells in contact with xylem conduits, which prevents repair of natural embolism; 2) relaxation of viscoelastic conduit wall polymers (cellulose, hemicelloluse, and lignin), which reduces cross-sectional conduit area; and 3) boiling of metastable water under tension, which causes conduit embolism. Results show that these processes operate on different time scales, suggesting that fire effects on transpiration vary with time since fire. The model can be linked with a three-dimensional physical fire spread model to predict size-dependent effects on individual trees, which can be used to estimate scaling of individual tree and stand-level transpiration.

The role of fuels for understanding fire behavior and fire effects

Treesearch

E. Louise Loudermilk; J. Kevin Hiers; Joseph J. O' Brien

2018-01-01

Fire ecology, which has emerged as a critical discipline, links the complex interactions that occur between fire regimes and ecosystems. The ecology of fuels, a first principle in fire ecology, identifies feedbacks between vegetation and fire behavior-a cyclic process that starts with fuels influencing fire behavior, which in turn governs patterns of postfire...

Influence of the veneer-framework interface on the mechanical behavior of ceramic veneers: a nonlinear finite element analysis.

PubMed

Lazari, Priscilla Cardoso; Sotto-Maior, Bruno Salles; Rocha, Eduardo Passos; de Villa Camargos, Germana; Del Bel Cury, Altair Antoninha

2014-10-01

The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures. The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions. The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework. Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used. Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Spatio-Temporal Analysis of Forest Fire Risk and Danger Using LANDSAT Imagery.

PubMed

Saglam, Bülent; Bilgili, Ertugrul; Dincdurmaz, Bahar; Kadiogulari, Ali Ihsan; Kücük, Ömer

2008-06-20

Computing fire danger and fire risk on a spatio-temporal scale is of crucial importance in fire management planning, and in the simulation of fire growth and development across a landscape. However, due to the complex nature of forests, fire risk and danger potential maps are considered one of the most difficult thematic layers to build up. Remote sensing and digital terrain data have been introduced for efficient discrete classification of fire risk and fire danger potential. In this study, two time-series data of Landsat imagery were used for determining spatio-temporal change of fire risk and danger potential in Korudag forest planning unit in northwestern Turkey. The method comprised the following two steps: (1) creation of indices of the factors influencing fire risk and danger; (2) evaluation of spatio-temporal changes in fire risk and danger of given areas using remote sensing as a quick and inexpensive means and determining the pace of forest cover change. Fire risk and danger potential indices were based on species composition, stand crown closure, stand development stage, insolation, slope and, proximity of agricultural lands to forest and distance from settlement areas. Using the indices generated, fire risk and danger maps were produced for the years 1987 and 2000. Spatio-temporal analyses were then realized based on the maps produced. Results obtained from the study showed that the use of Landsat imagery provided a valuable characterization and mapping of vegetation structure and type with overall classification accuracy higher than 83%.

Fire danger and fire behavior modeling systems in Australia, Europe, and North America

Treesearch

Francis M. Fujioka; A. Malcolm Gill; Domingos X. Viegas; B. Mike Wotton

2009-01-01

Wildland fire occurrence and behavior are complex phenomena involving essentially fuel (vegetation), topography, and weather. Fire managers around the world use a variety of systems to track and predict fire danger and fire behavior, at spatial scales that span from local to global extents, and temporal scales ranging from minutes to seasons. The fire management...

Aids to determining fuel models for estimating fire behavior

Treesearch

Hal E. Anderson

1982-01-01

Presents photographs of wildland vegetation appropriate for the 13 fuel models used in mathematical models of fire behavior. Fuel model descriptions include fire behavior associated with each fuel and its physical characteristics. A similarity chart cross-references the 13 fire behavior fuel models to the 20 fuel models used in the National Fire Danger Rating System....

Climatic and weather factors affecting fire occurrence and behavior

Treesearch

Randall P. Benson; John O. Roads; David R. Weise

2009-01-01

Weather and climate have a profound influence on wildland fire ignition potential, fire behavior, and fire severity. Local weather and climate are affected by large-scale patterns of winds over the hemispheres that predispose wildland fuels to fire. The characteristics of wildland fuels, especially the moisture content, ultimately determine fire behavior and the impact...

Fire Behavior System for the Full Range of Fire Management Needs

Treesearch

Richard C. Rothermel; Patricia L. Andrews

1987-01-01

An "integrated fire behavior/fire danger rating system" should be "seamless" to avoid requiring choices among alternate, independent systems. Descriptions of fuel moisture, fuels, and fire behavior should be standardized, permitting information to flow easily through the spectrum of fire management needs. The level of resolution depends on the...

Modelling global CO2 emissions into the atmosphere from crown, ground, and peat fires

NASA Astrophysics Data System (ADS)

Eliseev, Alexey V.; Mokhov, Igor I.; Chernokulsky, Alexander V.

2015-04-01

The scheme for natural fires implemented in the climate model (CM) developed at the A.M. Obukhov Institute of Atmospheric Physics (IAP RAS) is extended by a module accounting for ground and peat fires. With the IAP RAS CM, the simulations are performed for 1700-2300 in accordance with the CMIP5 (Coupled Models Intercomparison Project, phase 5) protocol. The modelled present-day burnt area, BA, and the corresponding CO2 emissions into the atmosphere E agree with the GFED-3.1 estimates at most regions. In the 21st century, under the RCP (Representative Concentration Pathways) scenarios, the global BA increases by 10-41% depending on scenario, and E increases by 11-39%. Under the mitigation scenario RCP 2.6, both BA and E slightly decrease in the 22nd-23rd centuries. For scenarios RCP 4.5, RCP 6.0, and RCP 8.5, they continue to increase in these two centuries. All these changes are mostly due to changes in natural fires activity in the boreal regions. Ground and peat fires contribute significantly to the total emissions of CO2 from natural fires (20-25% at the global scale depending on scenario and calendar year). Peat fires markedly intensify interannual variability of regional CO2 emissions from natural fires.

Determination of pumper truck intervention ratios in zones with high fire potential by using geographical information system

NASA Astrophysics Data System (ADS)

Aricak, Burak; Kucuk, Omer; Enez, Korhan

2014-01-01

Fighting forest fires not only depends on the forest type, topography, and weather conditions, but is also closely related to the technical properties of fire-fighting equipment. Firefighting is an important part of fire management planning. However, because of the complex nature of forests, creating thematic layers to generate potential fire risk maps is difficult. The use of remote sensing data has become an efficient method for the discrete classification of potential fire risks. The study was located in the Central District of the Kastamonu Regional Forest Directorate, covering an area of 24,320 ha, 15,685 ha of which is forested. On the basis of stand age, crown closure, and tree species, the sizes and distributions of potential fire risk zones within the study area were determined using high-resolution GeoEye satellite imagery and geographical information system data. The status of pumper truck intervention in zones with high fire risk and the sufficiency of existing forest roads within an existing forest network were discussed based on combustible matter characteristics. Pumper truck intervention was 83% for high-risk zones, 79% for medium-risk zones, and 78% for low-risk zones. A pumper truck intervention area map along existing roads was also created.

Influences of coupled fire-atmosphere interaction on wildfire behavior

NASA Astrophysics Data System (ADS)

Linn, R.; Winterkamp, J.; Jonko, A. K.; Runde, I.; Canfield, J.; Parsons, R.; Sieg, C.

2017-12-01

Two-way interactions between fire and the environment affect fire behavior at scales ranging from buoyancy-induced mixing and turbulence to fire-scale circulations that retard or increase fire spread. Advances in computing have created new opportunities for the exploration of coupled fire-atmosphere behavior using numerical models that represent interactions between the dominant processes driving wildfire behavior, including convective and radiative heat transfer, aerodynamic drag and buoyant response of the atmosphere to heat released by the fire. Such models are not practical for operational, faster-than-real-time fire prediction due to their computational and data requirements. However, they are valuable tools for exploring influences of fire-atmosphere feedbacks on fire behavior as they explicitly simulate atmospheric motions surrounding fires from meter to kilometer scales. We use the coupled fire-atmosphere model FIRETEC to gain new insights into aspects of fire behavior that have been observed in the field and laboratory, to carry out sensitivity analysis that is impractical through observations and to pose new hypotheses that can be tested experimentally. Specifically, we use FIRETEC to study the following multi-scale coupled fire-atmosphere interactions: 1) 3D fire-atmosphere interaction that dictates multi-scale fire line dynamics; 2) influence of vegetation heterogeneity and variability in wind fields on predictability of fire spread; 3) fundamental impacts of topography on fire spread. These numerical studies support new conceptual models for the dominant roles of multi-scale fluid dynamics in determining fire spread, including the roles of crosswind fire line-intensity variations on heat transfer to unburned fuels and the role of fire line depth expansion in upslope acceleration of fires.

The effect of salvage logging on surface fuel loads and fuel moisture in beetle-infested lodgepole pine forests

Treesearch

Paul R. Hood; Kellen N. Nelson; Charles C. Rhoades; Daniel B. Tinker

2017-01-01

Widespread tree mortality from mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) outbreaks has prompted forest management activities to reduce crown fire hazard in the Rocky Mountain region. However, little is known about how beetle-related salvage logging and biomass utilization options affect woody surface fuel loads and fuel moisture dynamics. We compared...

Effects of seasonal prescribved fires on residual overstory trees in oak-dominate shelterwood stands

Treesearch

Patrick H. Brose; David H. Van Lear

1999-01-01

A study was initiated in 1994 to evaluate the degree of bole damage and crown decline residual overstory trees would experience because of prescribed burning of shelterwood stands. Three oak-dominated shelterwood stands, partially harvested 2 to 4 yr earlier, were divided into four treatments (unburned control, spring burn, summer burn, and winter burn). Fifteen...

The effects of sudden oak death on foliar moisture content and crown fire potential in tanoak

Treesearch

H. Kuljian; J.M. Varner

2010-01-01

The introduction of non-native pathogens can have profound effects on forest ecosystems resulting in loss of species, changes in species composition, and altered fuel structure. The introduction of Phytophthora ramorum, the pathogen recognized as causing Sudden Oak Death (SOD), leads to rapid decline and mortality of tanoak (Lithocarpus densiflorus) in forests of...

Midstory reduction treatments with a Woodgator T-5

Treesearch

Dana Mitchell; Bob Rummer

2001-01-01

Many stands in the Southern U.S. have developed an increased amount of non-commercial midstory and understory components. Managers may not be able to prescribe burn these stands, due to smoke management concerns or risk of fire climbing into the crowns of the overstory trees. A variety of machines have been designed to mulch, shred, or chop standing vegetation to clear...

Fuel reduction in residential and scenic forests: A comparison of three treatments in a western Montana ponderosa pine stand

Treesearch

Joe H. Scott

1998-01-01

Three contrasting thinning treatments to reduce fire hazard were implemented in a 100-year-old ponderosa pine/Douglas-fir (Pinus ponderosa/Pseudotsuga menzesii) stand on the Lolo National Forest, MT. All treatments included a commercial thinning designed to reduce crown fuels and provide revenue to offset costs. The treatments are...

Volume and crown characteristics of juvenile loblolly pine grown at various ratios of between and within row spacings

Treesearch

John R. Britt; Jason P. Reynolds

2013-01-01

In plantation forestry, several silvicultural treatments can be row oriented. When rows are treated individually, planting trees in wider rows may result in lower silvicultural treatment cost, facilitate future operations, such as thinning and fire fighting, and provide a longer period with open canopy conditions. All these scenarios could provide benefit to landowners...

Mulching fuels treatments promote understory plant communities in three Colorado, USA, coniferous forest types

Treesearch

Paula J. Fornwalt; Monique E. Rocca; Michael Battaglia; Charles C. Rhoades; Michael G. Ryan

2017-01-01

Mulching fuels treatments have been increasingly implemented by forest managers in the western USA to reduce crown fire hazard. These treatments use heavy machinery to masticate or chip unwanted shrubs and small-diameter trees and broadcast the mulched material on the ground. Because mulching treatments are relatively novel and have no natural analog, their ecological...

Fire effects on tree overstories in the oak savannas of the Southwestern Borderlands Region

Treesearch

Peter F. Ffolliott; Gerald J. Gottfried; Cody L. Stropki; Hui Chen; Daniel G. Neary

2011-01-01

Effects of cool-season and warm-season prescribed burning treatments and a wildfire on tree overstories in oak savannas on the Cascabel Watersheds of the Southwestern Borderlands Region are reported in this paper. Information on the initial survival, levels of crown damage, species compositions and densities, annual growth rates, and basal sprouting following these...

Fire as a Removal Mechanism of Pyrogenic Carbon in Soils: Effects of Fire Characteristics and Pyrogenic Carbon Properties

NASA Astrophysics Data System (ADS)

Santin, C.; Doerr, S.; Merino, A.

2016-12-01

Pyrogenic carbon (PyC) produced during vegetation fires represents one of the most degradation resistant organic carbon pools and has important implications for the global carbon cycle. Its long-term fate in the environment and the processes leading to its degradation are the subject of much debate. Its consumption in subsequent fires is usually highlighted in the literature as a possible major abiotic loss mechanism of PyC in soils. However, the only two studies that have empirically tested this hypothesis found only minor losses of existing PyC, suggesting that subsequent fire is not a major cause of PyC loss (Santin et al. 2013 median mass losses <15% in an experimental boreal forest fire and Saiz et al. 2014 average mass losses <8% in a prescribed fire in an open savannah woodland). Here we present new empirical data obtained in i) a high-intensity crown fire; ii) a surface low-intensity fire, and iii) a smouldering wildfire in boreal forests and show that the actual PyC combustion during subsequent fires is very variable and depends on both the characteristics of the fire and on the properties of the PyC. References- Saiz G, Goodrick I, Wurster C, Zimmermann MPN, Bird MI (2014) Charcoal recombustion efficiency in tropical savannas. Geoderma, 219, 40-45. - Santin C, Doerr SH, Preston C, Bryant R (2013) Consumption of residual pyrogenic carbon by wildfire. International Journal of Wildland Fire, 22, 1072-1077.

Developing custom fire behavior fuel models from ecologically complex fuel structures for upper Atlantic Coastal Plain forests

Treesearch

Bernard R. Parresol; Joe H. Scott; Anne Andreu; Susan Prichard; Laurie Kurth

2012-01-01

Currently geospatial fire behavior analyses are performed with an array of fire behavior modeling systems such as FARSITE, FlamMap, and the Large Fire Simulation System. These systems currently require standard or customized surface fire behavior fuel models as inputs that are often assigned through remote sensing information. The ability to handle hundreds or...

Changes in fire weather distributions: effects on predicted fire behavior

Treesearch

Lucy A. Salazar; Larry S. Bradshaw

1984-01-01

Data that represent average worst fire weather for a particular area are used to index daily fire danger; however, they do not account for different locations or diurnal weather changes that significantly affect fire behavior potential. To study the effects that selected changes in weather databases have on computed fire behavior parameters, weather data for the...

Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

PubMed

Brondani, Lucas Pradebon; Pereira-Cenci, Tatiana; Wandsher, Vinicius Felipe; Pereira, Gabriel Kalil; Valandro, Luis Felipe; Bergoli, César Dalmolin

2017-04-10

Resin cements are often used for single crown cementation due to their physical properties. Self-adhesive resin cements gained widespread due to their simplified technique compared to regular resin cement. However, there is lacking clinical evidence about the long-term behavior of this material. The aim of this prospective clinical trial was to assess the survival rates of metal-ceramic crowns cemented with self-adhesive resin cement up to six years. One hundred and twenty-nine subjects received 152 metal-ceramic crowns. The cementation procedures were standardized and performed by previously trained operators. The crowns were assessed as to primary outcome (debonding) and FDI criteria. Statistical analysis was performed using Kaplan-Meier statistics and descriptive analysis. Three failures occurred (debonding), resulting in a 97.6% survival rate. FDI criteria assessment resulted in scores 1 and 2 (acceptable clinical evaluation) for all surviving crowns. The use of self-adhesive resin cement is a feasible alternative for metal-ceramic crowns cementation, achieving high and adequate survival rates.

Clinical Performance of Pedo Jacket Crowns in Maxillary Anterior Primary Teeth.

PubMed

Castro, Aimee; Badr, Sherine B Y; El-Badrawy, Wafa; Kulkarni, Gajanan

2016-09-15

To assess the clinical performance of Pedo Jacket crowns for restoration of carious primary anterior teeth. A total of 129 carious primary incisors and canines of 48 children younger than 71 months of age- were restored with Pedo Jacket crowns and resin-modified glass ionomer cementation. They were assessed for: ease of use; presence of recurrent decay; wear; partial or complete loss of the crown; color stability; gingival health; and overall clinical success over a 12-month follow-up. The patient's behavior at the restorative appointment during crown placement was also assessed. An overall clinical success of 89.5 percent of the teeth in 87.3 percent of the children was seen one year later. The crowns were easy to use, even in uncooperative children. The color stability, wear, plaque accumulation, and gingival health were acceptable. Discoloration, wear, or complete loss of the crown were found in 13.1 percent, 5.4 percent, and 7.6 percent of children, respectively. Although not statistically significant, failures were associated with poor patient cooperation at the time of crown placement, poor oral hygiene, or operator error. Pedo Jacket crowns are a viable treatment alternative for carious maxillary primary anterior teeth.

Three-year clinical evaluation of two ceramic crown systems: a preliminary study.

PubMed

Etman, Maged K; Woolford, M J

2010-02-01

The clinical performance and failure mechanisms of recently introduced ceramic crown systems used to restore posterior teeth have not been adequately examined. The purpose of this prospective clinical study was to evaluate and compare the clinical performance of 2 new ceramic crown systems with that of metal ceramic crowns using modified United States Public Health Services (USPHS) criteria. Ninety posterior teeth requiring crown restorations in 48 patients were randomized into 3 equal groups (n=30) for which different crown systems were used: an experimental hot-pressed glass ceramic based on a modified lithium disilicate ceramic (IPS e.max Press), an alumina-coping-based ceramic (Procera AllCeram), and a metal ceramic (Simidur S 2 veneered with IPS Classic Porcelain). The crowns were assessed over 3 years using the modified USPHS criteria. Crowns that developed visible cracks were sectioned and removed, and the surfaces were analyzed using a scanning electron microscope (SEM). The data were analyzed using the Kruskal-Wallis nonparametric statistical test, followed by the Mann-Whitney test with Bonferroni correction (alpha=.05). USPHS evaluation showed that the IPS e.max Press and metal ceramic crowns experienced fewer clinical changes than Procera AllCeram. Visible roughness, wear, and deformity were noticed in occlusal contact areas of Procera AllCeram crowns. SEM images showed well defined wear facets in both ceramic crown systems. Kruskal-Wallis tests showed a significant difference (P<.05) in Alpha scores among the 3 crown systems. Mann-Whitney tests showed significant differences among groups. IPS e.max Press crowns demonstrated clinical behavior comparable to Procera AllCeram and metal ceramic crowns, but the wear resistance of this crown type was superior to the Procera AllCeram crowns, according to modified USPHS criteria.

CAD/CAM glass ceramics for single-tooth implant crowns: a finite element analysis.

PubMed

Akça, Kvanç; Cavusoglu, Yeliz; Sagirkaya, Elcin; Aybar, Buket; Cehreli, Murat Cavit

2013-12-01

To evaluate the load distribution of CAD/CAM mono-ceramic crowns supported with single-tooth implants in functional area. A 3-dimensional numerical model of a soft tissue-level implant was constructed with cement-retained abutment to support glass ceramic machinable crown. Implant-abutment complex and the retained crown were embedded in a Ø 1.5 × 1.5 cm geometric matrix for evaluation of mechanical behavior of mono-ceramic CAD/CAM aluminosilicate and leucite glass crown materials. Laterally positioned axial load of 300 N was applied on the crowns. Resulting principal stresses in the mono-ceramic crowns were evaluated in relation to different glass ceramic materials. The highest compressive stresses were observed at the cervical region of the buccal aspect of the crowns and were 89.98 and 89.99 MPa, for aluminosilicate and leucite glass ceramics, respectively. The highest tensile stresses were observed at the collar of the lingual part of the crowns and were 24.54 and 25.39 MPa, respectively. Stresses induced upon 300 N static loading of CAD/CAM aluminosalicate and leucite glass ceramics are below the compressive strength of the materials. Impact loads may actuate the progress to end failure of mono-ceramic crowns supported by metallic implant abutments.

Introduction-2nd Fire Behavior and Fuels Conference: The fire environment-innovations, management, and policy

Treesearch

Wayne Cook; Bret W. Butler

2007-01-01

The 2nd Fire Behavior and Fuels Conference: Fire Environment -- Innovations, Management and Policy was held in Destin, FL, March 26-30, 2007. Following on the success of the 1st Fire Behavior and Fuels Conference, this conference was initiated in response to the needs of the National Wildfire Coordinating Group -- Fire Environment Working Team.

A comparison of geospatially modeled fire behavior and fire management utility of three data sources in the southeastern United States

Treesearch

LaWen T. Hollingsworth; Laurie L. Kurth; Bernard R. Parresol; Roger D. Ottmar; Susan J. Prichard

2012-01-01

Landscape-scale fire behavior analyses are important to inform decisions on resource management projects that meet land management objectives and protect values from adverse consequences of fire. Deterministic and probabilistic geospatial fire behavior analyses are conducted with various modeling systems including FARSITE, FlamMap, FSPro, and Large Fire Simulation...

Employing Numerical Weather Models to Enhance Fire Weather and Fire Behavior Predictions

Treesearch

Joseph J. Charney; Lesley A. Fusina

2006-01-01

This paper presents an assessment of fire weather and fire behavior predictions produced by a numerical weather prediction model similar to those used by operational weather forecasters when preparing their forecasts. The PSU/NCAR MM5 model is used to simulate the weather conditions associated with three fire episodes in June 2005. Extreme fire behavior was reported...

Changes to Cretaceous surface fire behaviour influenced the spread of the early angiosperms.

PubMed

Belcher, Claire M; Hudspith, Victoria A

2017-02-01

Angiosperms evolved and diversified during the Cretaceous period. Early angiosperms were short-stature weedy plants thought to have increased fire frequency and mortality in gymnosperm forest, aiding their own expansion. However, no explorations have considered whether the range of novel fuel types that diversified throughout the Cretaceous also altered fire behaviour, which should link more strongly to mortality than fire frequency alone. We measured ignitability and heat of combustion in analogue Cretaceous understorey fuels (conifer litter, ferns, weedy and shrubby angiosperms) and used these data to model palaeofire behaviour. Variations in ignition, driven by weedy angiosperms alone, were found to have been a less important feedback to changes in Cretaceous fire activity than previously estimated. Our model estimates suggest that fires in shrub and fern understories had significantly greater fireline intensities than those fuelled by conifer litter or weedy angiosperms, and whilst fern understories supported the most rapid fire spread, angiosperm shrubs delivered the largest amount of heat per unit area. The higher fireline intensities predicted by the models led to estimates of enhanced scorch of the gymnosperm canopy and a greater chance of transitioning to crown fires. Therefore, changes in fire behaviour driven by the addition of new Cretaceous fuel groups may have assisted the angiosperm expansion. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Trends and Variability of Global Fire Emissions Due To Historical Anthropogenic Activities

NASA Astrophysics Data System (ADS)

Ward, Daniel S.; Shevliakova, Elena; Malyshev, Sergey; Rabin, Sam

2018-01-01

Globally, fires are a major source of carbon from the terrestrial biosphere to the atmosphere, occurring on a seasonal cycle and with substantial interannual variability. To understand past trends and variability in sources and sinks of terrestrial carbon, we need quantitative estimates of global fire distributions. Here we introduce an updated version of the Fire Including Natural and Agricultural Lands model, version 2 (FINAL.2), modified to include multiday burning and enhanced fire spread rate in forest crowns. We demonstrate that the improved model reproduces the interannual variability and spatial distribution of fire emissions reported in present-day remotely sensed inventories. We use FINAL.2 to simulate historical (post-1700) fires and attribute past fire trends and variability to individual drivers: land use and land cover change, population growth, and lightning variability. Global fire emissions of carbon increase by about 10% between 1700 and 1900, reaching a maximum of 3.4 Pg C yr-1 in the 1910s, followed by a decrease to about 5% below year 1700 levels by 2010. The decrease in emissions from the 1910s to the present day is driven mainly by land use change, with a smaller contribution from increased fire suppression due to increased human population and is largest in Sub-Saharan Africa and South Asia. Interannual variability of global fire emissions is similar in the present day as in the early historical period, but present-day wildfires would be more variable in the absence of land use change.

Quaternary Charcoal Records from Western North and South America: Linkages to Fire, Climate, and Vegetation Change

NASA Astrophysics Data System (ADS)

Whitlock, C.; Marlon, J.; Bartlein, P.

2006-12-01

Particulate charcoal preserved in lake sediments has become an important tool for examining the long-term role of fire as an ecosystem process. The record of microscopic charcoal (100 micron diameter or less) offers information on regional burning patterns, whereas macroscopic particles travel less far and are used to infer local fire history. Reconstruction of past fire activity is based on observations of modern charcoal production, transport, and deposition; modeling; and information on current fire regimes. Approaches and statistics used to interpret charcoal records generally focus on (1) quantifying charcoal content in contiguous samples, (2) determining an appropriate age model, (3) converting raw data to charcoal accumulation rates, and (4) extracting fire signal from noise. Detection of signal in charcoal time series is based on knowledge of recent fires provided by dendrochronological and documentary data. Additional paleofire information is obtained from stratigraphic changes in charcoal composition, pollen assemblages adapted to fire, and other paleoenvironmental proxy. Fire-history studies from western North and South America provide examples of Holocene fire-history reconstructions at spatial scales ranging from watershed to regional. Individual sites show dramatic shifts from crown to surface fire regimes associated with major changes in vegetation. Networks of records reveal regional variations in fire activity and vegetation that are attributed to insolation- driven shifts in atmospheric circulation and changes in short-term climate variability. A global database of paleofire records under development offers an opportunity to consider continental-scale fire patterns and their broad consequences for vegetation dynamics, biogeochemical cycling, and atmospheric chemistry.

Predicting fire behavior in U.S. Mediterranean ecosystems

Treesearch

Frank A. Albini; Earl B. Anderson

1982-01-01

Quantification and methods of prediction of wildland fire behavior are discussed briefly and factors of particular relevance to the prediction of fire behavior in Mediterranean ecosystems are reviewed. A computer-based system which uses relevant fuel information and current weather data to predict fire behavior is in operation in southern California. Some of the...

Fires and fuels: Vegetation change over time in the Zuni Mountains, New Mexico

NASA Astrophysics Data System (ADS)

Wylie, Luke Anthony

The Zuni Mountains are a region that has been dramatically changed by human interference. Anthropogenically, fire suppression practices have allowed a buildup of fuels and caused a change in the fire-adapted ponderosa pine ecosystem such that the new ecosystem now incorporates many fire-intolerant species. As a result, the low-severity fires that the ecosystem once depended on to regenerate the forest are much reduced, and these low-severity fires are now replaced by crown-level infernos that threaten the forest and nearby towns. In order to combat these effects, land managers are implementing fuel reduction practices and are striving to better understand the local ecosystem. In this study, a predictive fire spread model (FARSITE) was implemented to predict spatio-temporal distribution of fire in the Zuni Mountains based on change in vegetation types that are most prone to fire. Using Landsat imagery and historical fire spread data from 2001 to 2014, the following research questions were investigated: (1) What variables are responsible for fire spread in the Zuni Mountains, New Mexico? (2) Which areas are prone to destructive and canopy level fires? and (3) How have the fuel model types that are most conducive to fire spread changed in the past twenty years? The utilization of spatial modeling and remote sensing to understand the interaction of meteorological variables and vegetation in predicting fire spread in this region is a novel approach. This study showed that (i) fires are more likely to occur in the valleys and high elevation grassland areas of the Zuni Mountains, (ii) certain vegetation types including grass and shrub lands in the area present a greater danger to canopy fire than others, and (iii) that these vegetation types have changed in the past sixteen years.

BehavePlus fire modeling system: Past, present, and future

Treesearch

Patricia L. Andrews

2007-01-01

Use of mathematical fire models to predict fire behavior and fire effects plays an important supporting role in wildland fire management. When used in conjunction with personal fire experience and a basic understanding of the fire models, predictions can be successfully applied to a range of fire management activities including wildfire behavior prediction, prescribed...

Observations on heat tolerance of southern pine needles. U.S

Treesearch

Ralph M. Nelson

1952-01-01

When forest fires burn through southern pine stands, effects on tree crowns range from no observable injury to complete browning and even total con­ sumption of all needles. Mortality and loss of growth that may follow are largely determined by the extent of damage to the foliage, particularly to the buds and twigs. Height of scorch line, as marked by yellowing or...

Holocene Vegetation and Fire Dynamics on the Chilcotin Plateau, BC, Canada

NASA Astrophysics Data System (ADS)

Brown, K. J.; Hebda, R.; Hawkes, B.

2014-12-01

The Chilcotin Plateau is a high elevation plateau in the west central interior of British Columbia, Canada. It is characterised by a continental climate and located in a rainshadow setting. Pine-dominated forests dominate. The region is prone to frequent fires and mountain pine beetle outbreaks. Several surface sediment cores and an overlapping Livingstone sediment core were collected from centrally-located Scum Lake and analysed for pollen, charcoal and insect remains. During the early-Holocene warm-dry interval, a non-arboreal vegetation community dominated by grass and sage dominated and surface fire disturbance was frequent. Model predictions suggest that non-arboreal vegetation may expand in this region in the future, suggesting that the fire regime will likewise change as in the early-Holocene. In the mid-Holocene, pine, possibly Pinus ponderosa, increased in abundance, suggesting that a surface fire regime persisted at that time. Pinus contorta pollen increased in the late-Holocene, representing the establishment of the modern forest and mixed/crown fire regime. Fire return intervals typically ranged between 20-100 years, consistent with tree-ring based observation (40-70 years). Analyses of the surface cores revealed that identifiable mountain pine beetle remains were rare, suggesting that alternative approaches may be required to assess to insect disturbance through time.

Impact of a community based fire prevention intervention on fire safety knowledge and behavior in elementary school children

PubMed Central

Hwang, V; Duchossois, G P; Garcia‐Espana, J F; Durbin, D R

2006-01-01

The objective of this study was to determine the impact of a community based fire prevention intervention directed only to parents on the fire safety knowledge and behavior in elementary school children. This was a prospective, quasi‐randomized controlled study in which third and fourth grade students from two elementary schools in an urban, poor, minority community completed knowledge/behavior surveys at baseline and following completion of the intervention. The intervention group received an in‐home visit from fire department personnel who installed free lithium smoke detectors and provided a fire escape plan. After accounting for a small difference in baseline summary scores of knowledge and behavior between the control and intervention groups, this study found a modest improvement in fire safety behavior among children whose families received a fire prevention intervention reflecting a change in household fire safety practices. However, there was no significant change in fire safety knowledge. PMID:17018679

Electron spin resonance and electron spin echo modulation of n-doxylstearic acid and N,N,N',N'-tetramethylbenzidine photoionization in sodium versus lithium dodecyl sulfate micellar solutions: effect of 15-crown-5 and 18-crown-6 ether addition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baglioni, P.; Rivara-Minten, E.; Kevan, L.

1988-08-11

Electron spin echo modulation and electron spin resonance spectra of photogenerated N,N,N',N'-tetramethylbenzidine (TMB) cation radical and n-doxylstearic acids (n-DSA) in frozen micellar solutions of sodium and lithium dodecyl sulfate containing 15-crown-5 and 18-crown-6 ethers in D/sub 2/O have been studied as a function of crown ether concentration. Modulation effects due to N-DSA with water deuteriums give direct evidence that both crown ethers are mainly located at the micellar interface and that this causes a decrease of the hydration of the micellar interface. Crown ether complexation constants for sodium and lithium micellar counterions are reported and show that 18-crown-6 > 15-crown-5more » for sodium counterion and 15-crown-5 > 18-crown-6 for lithium counterion. Modulation effects from TMB/sup +/ interaction with water deuteriums indicate that the TMB molecule moves toward the micelle interfacial region when sodium or lithium cations are complexed by crown ethers. The TMB/sup +/ yield upon TMB photoionization increases by about 10% with crown ether addition for SDS and LDS micellar systems, but it is greater if the absolute values for the LDS system are compared to those for the SDS micellar system. This behavior correlates with the strength of TMB/sup +/-water interactions and suggests that the main factor in the photoionization efficiency is the photocation-water interaction.« less

Charts for interpreting wildland fire behavior characteristics

Treesearch

Patricia L. Andrews; Richard C. Rothermel

1982-01-01

The fire characteristics chart is proposed as a graphical method ofpresenting two primary characteristics of fire behavior – spread rate and intensity. Its primary use is communicating and interpreting either site-specific predictions of fire behavior or National Fire-Danger Rating System (NFDRS) indexes and components. Rate of spread, heat per unit area, flame length...

In-situ characterization of wildland fire behavior

Treesearch

Bret Butler; D. Jimenez; J. Forthofer; Paul Sopko; K. Shannon; Jim Reardon

2010-01-01

A system consisting of two enclosures has been developed to characterize wildand fire behavior: The first enclosure is a sensor/data logger combination that measures and records convective/radiant energy released by the fire. The second is a digital video camera housed in a fire proof enclosure that records visual images of fire behavior. Together this system provides...

75 FR 58347 - Information Collection; Overcoming Barriers to Wildland Fire Defensible Space Behaviors

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-24

... Information Collection; Overcoming Barriers to Wildland Fire Defensible Space Behaviors AGENCY: Forest Service... new information collection, Overcoming Barriers to Wildland Fire Defensible Space Behaviors. DATES... time, Monday through Friday. SUPPLEMENTARY INFORMATION: Title: Overcoming Barriers to Wildland Fire...

An experimental demonstration of stem damage as a predictor of fire-caused mortality for ponderosa pine

USGS Publications Warehouse

van Mantgem, P.; Schwartz, M.

2004-01-01

We subjected 159 small ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) to treatments designed to test the relative importance of stem damage as a predictor of postfire mortality. The treatments consisted of a group with the basal bark artificially thinned, a second group with fuels removed from the base of the stem, and an untreated control. Following prescribed burning, crown scorch severity was equivalent among the groups. Postfire mortality was significantly less frequent in the fuels removal group than in the bark removal and control groups. No model of mortality for the fuels removal group was possible, because dead trees constituted <4% of subject trees. Mortality in the bark removal group was best predicted by crown scorch and stem scorch severity, whereas death in the control group was predicted by crown scorch severity and bark thickness. The relative lack of mortality in the fuels removal group and the increased sensitivity to stem damage in the bark removal group suggest that stem damage is a critical determinant of postfire mortality for small ponderosa pine.

Fire-mediated disruptive selection can explain the reseeder-resprouter dichotomy in Mediterranean-type vegetation.

PubMed

Altwegg, Res; De Klerk, Helen M; Midgley, Guy F

2015-02-01

Crown fire is a key selective pressure in Mediterranean-type plant communities. Adaptive responses to fire regimes involve trade-offs between investment for persistence (fire survival and resprouting) and reproduction (fire mortality, fast growth to reproductive maturity, and reseeding) as investments that enhance adult survival lower growth and reproductive rates. Southern hemisphere Mediterranean-type ecosystems are dominated by species with either endogenous regeneration from adult resprouting or fire-triggered seedling recruitment. Specifically, on nutrient-poor soils, these are either resprouting or reseeding life histories, with few intermediate forms, despite the fact that the transition between strategies is evolutionarily labile. How did this strong dichotomy evolve? We address this question by developing a stochastic demographic model to assess determinants of relative fitness of reseeders, resprouters and hypothetical intermediate forms. The model was parameterised using published demographic data from South African protea species and run over various relevant fire regime parameters facets. At intermediate fire return intervals, trade-offs between investment in growth versus fire resilience can cause fitness to peak at either of the extremes of the reseeder-resprouter continuum, especially when assuming realistic non-linear shapes for these trade-offs. Under these circumstances, the fitness landscape exhibits a saddle which could lead to disruptive selection. The fitness gradient between the peaks was shallow, which may explain why this life-history trait is phylogenetically labile. Resprouters had maximum fitness at shorter fire-return intervals than reseeders. The model suggests that a strong dichotomy in fire survival strategy depends on a non-linear trade-off between growth and fire persistence traits.

Stochastic representation of fire behavior in a wildland fire protection planning model for California.

Treesearch

J. Keith Gilless; Jeremy S. Fried

1998-01-01

A fire behavior module was developed for the California Fire Economics Simulator version 2 (CFES2), a stochastic simulation model of initial attack on wildland fire used by the California Department of Forestry and Fire Protection. Fire rate of spread (ROS) and fire dispatch level (FDL) for simulated fires "occurring" on the same day are determined by making...

Modeling aeolian transport in response to succession, disturbance and future climate: Dynamic long-term risk assessment for contaminant redistribution

USGS Publications Warehouse

Breshears, D.D.; Kirchner, T.B.; Whicker, J.J.; Field, J.P.; Allen, Craig D.

2012-01-01

Aeolian sediment transport is a fundamental process redistributing sediment, nutrients, and contaminants in dryland ecosystems. Over time frames of centuries or longer, horizontal sediment fluxes and associated rates of contaminant transport are likely to be influenced by succession, disturbances, and changes in climate, yet models of horizontal sediment transport that account for these fundamental factors are lacking, precluding in large part accurate assessment of human health risks associated with persistent soil-bound contaminants. We present a simple model based on empirical measurements of horizontal sediment transport (predominantly saltation) to predict potential contaminant transport rates for recently disturbed sites such as a landfill cover. Omnidirectional transport is estimated within vegetation that changes using a simple Markov model that simulates successional trajectory and considers three types of short-term disturbances (surface fire, crown fire, and drought-induced plant mortality) under current and projected climates. The model results highlight that movement of contaminated soil is sensitive to vegetation dynamics and increases substantially (e.g., > fivefold) when disturbance and/or future climate are considered. The time-dependent responses in horizontal sediment fluxes and associated contaminant fluxes were sensitive to variability in the timing of disturbance, with longer intervals between disturbance allowing woody plants to become dominant and crown fire and drought abruptly reducing woody plant cover. Our results, which have direct implications for contaminant transport and landfill management in the specific context of our assessment, also have general relevance because they highlight the need to more fully account for vegetation dynamics, disturbance, and changing climate in aeolian process studies.

Fire weather and fire behavior in the 1966 loop fire

Treesearch

C.M. Countryman; M.A. Fosberg; R.C. Rothermel; M.J. Schroeder

1968-01-01

Southern California regularly experiences a wind condition known as the Santa Ana winds. This paper describes the phenomenon and the effects it had on fire behavior during the 1966 Loop Fire in the Angeles National Forest, which claimed the lives of 12 fire fighters.

Fire behavior, fuel treatments, and fire suppression on the Hayman Fire - Part 4: Relation of roads to burn severity

Treesearch

Charles W. McHugh; Mark A. Finney

2003-01-01

Effects of roads on fire behavior intensity and severity can be studied directly or indirectly. A direct study of road effects would include uses by fire suppression, burnout operations, and delay of fire progress at the roadside. Interpretations after the fire burns are easily confounded by the unknown nature of suppression activities and fire arrival time, and fire...

Bald Mountain Fire, Eagle Cap Wilderness Area, Wallowa-Whitman National Forest, FARSITE analysis

Treesearch

LaWen Hollingsworth

2012-01-01

While the Near Term Fire Behavior analysis option in WFDSS is similar to FARSITE, the advantage of using FARSITE lies in the ability to use gridded winds which produces more reliable fire behavior results in complex terrain. A couple of FARSITE simulations were completed to evaluate fire growth and fire behavior in relation to the values, notably Red's Horse Ranch...

Fuel type characterization and potential fire behavior estimation in Sardinia and Corsica islands

NASA Astrophysics Data System (ADS)

Bacciu, V.; Pellizzaro, G.; Santoni, P.; Arca, B.; Ventura, A.; Salis, M.; Barboni, T.; Leroy, V.; Cancellieri, D.; Leoni, E.; Ferrat, L.; Perez, Y.; Duce, P.; Spano, D.

2012-04-01

Wildland fires represent a serious threat to forests and wooded areas of the Mediterranean Basin. As recorded by the European Commission (2009), during the last decade Southern Countries have experienced an annual average of about 50,000 forest fires and about 470,000 burned hectares. The factor that can be directly manipulated in order to minimize fire intensity and reduce other fire impacts, such as three mortality, smoke emission, and soil erosion, is wildland fuel. Fuel characteristics, such as vegetation cover, type, humidity status, and biomass and necromass loading are critical variables in affecting wildland fire occurrence, contributing to the spread, intensity, and severity of fires. Therefore, the availability of accurate fuel data at different spatial and temporal scales is needed for fire management applications, including fire behavior and danger prediction, fire fighting, fire effects simulation, and ecosystem simulation modeling. In this context, the main aims of our work are to describe the vegetation parameters involved in combustion processes and develop fire behavior fuel maps. The overall work plan is based firstly on the identification and description of the different fuel types mainly affected by fire occurrence in Sardinia (Italy) and Corsica (France) Islands, and secondly on the clusterization of the selected fuel types in relation to their potential fire behavior. In the first part of the work, the available time series of fire event perimeters and the land use map data were analyzed with the purpose of identifying the main land use types affected by fires. Thus, field sampling sites were randomly identified on the selected vegetation types and several fuel variables were collected (live and dead fuel load partitioned following Deeming et al., (1977), depth of fuel layer, plant cover, surface area-to-volume ratio, heat content). In the second part of the work, the potential fire behavior for every experimental site was simulated using BEHAVE fire behavior prediction system (Andrews, 1989) and experimental fuel data. Fire behavior was simulated by setting different weather scenarios representing the most frequent summer meteorological conditions. The simulation outputs (fireline intensity, rate of spread, flame length) were then analyzed for clustering the different fuel types in relation to their potential fire behavior. The results of this analysis can be used to produce fire behavior fuel maps that are important tools in evaluating fire hazard and risk for land management planning, locating and rating fuel treatments, and aiding in environmental assessments and fire danger programs modeling. This work is supported by FUME Project FP7-ENV-2009-1, Grant Agreement Number 243888 and Proterina-C Project, EU Italia-Francia Marittimo 2007-2013 Programme.

Fatigue Resistance of CAD/CAM Resin Composite Molar Crowns

PubMed Central

Shembish, Fatma A.; Tong, Hui; Kaizer, Marina; Janal, Malvin N.; Thompson, Van P.; Opdam, Niek J.; Zhang, Yu

2016-01-01

Objective To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. Methods Fully anatomically shaped monolithic resin composite molar crowns (Lava Ultimate, n = 24) and leucite reinforced glass-ceramic crowns (IPS Empress CAD, n = 24) were fabricated using CAD/CAM systems. Crowns were cemented on aged dentin-like resin composite tooth replicas (Filtek Z100) with resin-based cements (RelyX Ultimate for Lava Ultimate or Multilink Automix for IPS Empress). Three step-stress profiles (aggressive, moderate and mild) were employed for the accelerated sliding-contact mouth-motion fatigue test. Twenty one crowns from each group were randomly distributed among these three profiles (1:2:4). Failure was designated as chip-off or bulk fracture. Optical and electronic microscopes were used to examine the occlusal surface and subsurface damages, as well as the material microstructures. Results The resin composite crowns showed only minor occlusal damage during mouth-motion step-stress fatigue loading up to 1700 N. Cross-sectional views revealed contact-induced cone cracks in all specimens, and flexural radial cracks in 2 crowns. Both cone and radial cracks were relatively small compared to the crown thickness. Extending these cracks to the threshold for catastrophic failure would require much higher indentation loads or more loading cycles. In contrast, all of the glass-ceramic crowns fractured, starting at loads of approximately 450 N. Significance Monolithic CAD/CAM resin composite crowns endure, with only superficial damage, fatigue loads 3 – 4 times higher than those causing catastrophic failure in glass-ceramic CAD crowns. PMID:26777092

Fire Technology Abstracts, volume 4, issue 1, August, 1981

NASA Astrophysics Data System (ADS)

Holtschlag, L. J.; Kuvshinoff, B. W.; Jernigan, J. B.

This bibliography contains over 400 citations with abstracts addressing various aspects of fire technology. Subjects cover the dynamics of fire, behavior and properties of materials, fire modeling and test burns, fire protection, fire safety, fire service organization, apparatus and equipment, fire prevention, suppression, planning, human behavior, medical problems, codes and standards, hazard identification, safe handling of materials, insurance, economics of loss and prevention, and more.

Stem sapwood permeability in relation to crown dominance and site quality in self-thinning fire-origin lodgepole pine stands.

PubMed

Reid, Douglas E B; Silins, Uldis; Lieffers, Victor J

2003-08-01

Stem sapwood hydraulic permeability, tree leaf area, sapwood basal area, earlywood to latewood ratio of annual rings, radial variation in hydraulic permeability and stem hydraulic capacity were examined in dominant (D), codominant (CD) and suppressed (SP) lodgepole pine (Pinus contorta Dougl. ex Loud.) trees growing on medium and poor sites. Hydraulic permeability on a sapwood area basis (ks) was lower in suppressed trees (0.71 x 10(-12) m2) compared to dominants (1.97 x 10(-12) m2) and codominants (1.79 x 10(-12) m2), and higher on medium than on poor sites. The leaf/sapwood area ratio (S) varied with crown dominance position (D > CD > SP) but not by site type. Leaf specific conductivity (kL) did not vary between crown classes or site types. The relationship between leaf area and stem hydraulic supply capacity (Q*) was strong, but differed among crown classes. Dominant trees and trees from the medium sites had a greater proportion of earlywood in outer rings of sapwood than suppressed trees. Sapwood permeability declined from the cambium to the sapwood-heartwood boundary in all samples, but the decline was more gradual in dominant trees compared to codominant and suppressed trees; differences in the radial variation in sapwood permeability may be related to differences in S. Sapwood permeability is positively related to crown dominance, whereas subdominant (CD and SP) trees have greater Q* in relation to leaf area, leading us to propose that this may give subdominant trees a survival advantage, slowing self-thinning.

Diurnal behavior and activity budget of the golden-crowned flying fox (Acerodon jubatus) in the Subic bay forest reserve area, the Philippines.

PubMed

Hengjan, Yupadee; Iida, Keisuke; Doysabas, Karla Cristine C; Phichitrasilp, Thanmaporn; Ohmori, Yasushige; Hondo, Eiichi

2017-10-07

Acerodon jubatus (the Golden-Crowned flying fox) is an endemic species in the Philippines, which was suspected to be a host of the Reston strain of the Ebola virus. As nocturnal animals, the flying foxes spend daytime at the roosting site, which they use for self-maintenance and reproduction. To understand the variation in diurnal behavior and time allocation for various activities in the Golden-Crowned flying fox, we investigated their daytime behavior and activity budget using instantaneous scan sampling and all occurrence focal sampling. Data collection was performed from 07:00 to 18:00 hr during January 8-17, 2017. The most frequent activity was sleeping (76.3%). The remaining activities were wing flapping (5.0%), self-grooming (4.2%), hanging relaxation (3.4%), wing spread (2.9%), movement (2.4%), mating/courtship (2.4%), aggression (1.9%), hanging alert (1.2%), excretion (0.1%) and scent marks (0.05%). The frequency of sleeping, wing flapping, self-grooming, hanging relaxation, aggression, mating/courtship and movement behaviors changed with the time of the day. Females allocated more time for resting than males, while males spent more time on the activities that helped enhance their mating opportunities, for example, movement, sexual activity and territorial behavior.

Diurnal behavior and activity budget of the golden-crowned flying fox (Acerodon jubatus) in the Subic bay forest reserve area, the Philippines

PubMed Central

HENGJAN, Yupadee; IIDA, Keisuke; DOYSABAS, Karla Cristine C.; PHICHITRASILP, Thanmaporn; OHMORI, Yasushige; HONDO, Eiichi

2017-01-01

Acerodon jubatus (the Golden-Crowned flying fox) is an endemic species in the Philippines, which was suspected to be a host of the Reston strain of the Ebola virus. As nocturnal animals, the flying foxes spend daytime at the roosting site, which they use for self-maintenance and reproduction. To understand the variation in diurnal behavior and time allocation for various activities in the Golden-Crowned flying fox, we investigated their daytime behavior and activity budget using instantaneous scan sampling and all occurrence focal sampling. Data collection was performed from 07:00 to 18:00 hr during January 8–17, 2017. The most frequent activity was sleeping (76.3%). The remaining activities were wing flapping (5.0%), self-grooming (4.2%), hanging relaxation (3.4%), wing spread (2.9%), movement (2.4%), mating/courtship (2.4%), aggression (1.9%), hanging alert (1.2%), excretion (0.1%) and scent marks (0.05%). The frequency of sleeping, wing flapping, self-grooming, hanging relaxation, aggression, mating/courtship and movement behaviors changed with the time of the day. Females allocated more time for resting than males, while males spent more time on the activities that helped enhance their mating opportunities, for example, movement, sexual activity and territorial behavior. PMID:28804092

Gis-Based Multi-Criteria Decision Analysis for Forest Fire Risk Mapping

NASA Astrophysics Data System (ADS)

Akay, A. E.; Erdoğan, A.

2017-11-01

The forested areas along the coastal zone of the Mediterranean region in Turkey are classified as first-degree fire sensitive areas. Forest fires are major environmental disaster that affects the sustainability of forest ecosystems. Besides, forest fires result in important economic losses and even threaten human lives. Thus, it is critical to determine the forested areas with fire risks and thereby minimize the damages on forest resources by taking necessary precaution measures in these areas. The risk of forest fire can be assessed based on various factors such as forest vegetation structures (tree species, crown closure, tree stage), topographic features (slope and aspect), and climatic parameters (temperature, wind). In this study, GIS-based Multi-Criteria Decision Analysis (MCDA) method was used to generate forest fire risk map. The study was implemented in the forested areas within Yayla Forest Enterprise Chiefs at Dursunbey Forest Enterprise Directorate which is classified as first degree fire sensitive area. In the solution process, "extAhp 2.0" plug-in running Analytic Hierarchy Process (AHP) method in ArcGIS 10.4.1 was used to categorize study area under five fire risk classes: extreme risk, high risk, moderate risk, and low risk. The results indicated that 23.81 % of the area was of extreme risk, while 25.81 % was of high risk. The result indicated that the most effective criterion was tree species, followed by tree stages. The aspect had the least effective criterion on forest fire risk. It was revealed that GIS techniques integrated with MCDA methods are effective tools to quickly estimate forest fire risk at low cost. The integration of these factors into GIS can be very useful to determine forested areas with high fire risk and also to plan forestry management after fire.

Relative impact of weather vs. fuels on fire regimes in coastal California

Treesearch

Jon E. Keeley

2008-01-01

Extreme fire weather is of over riding importance in determining fire behavior in coastal chaparral and on these landscapes fire suppression policy has not resulted in fire exclusion. There is regional variation in foehn winds, which are most important in southern California. Under these severe fire weather conditions fuel age does not constrain fire behavior. As a...

Performance of fire behavior fuel models developed for the Rothermel Surface Fire Spread Model

Treesearch

Robert Ziel; W. Matt Jolly

2009-01-01

In 2005, 40 new fire behavior fuel models were published for use with the Rothermel Surface Fire Spread Model. These new models are intended to augment the original 13 developed in 1972 and 1976. As a compiled set of quantitative fuel descriptions that serve as input to the Rothermel model, the selected fire behavior fuel model has always been critical to the resulting...

Standard fire behavior fuel models: a comprehensive set for use with Rothermel's surface fire spread model

Treesearch

Joe H. Scott; Robert E. Burgan

2005-01-01

This report describes a new set of standard fire behavior fuel models for use with Rothermel's surface fire spread model and the relationship of the new set to the original set of 13 fire behavior fuel models. To assist with transition to using the new fuel models, a fuel model selection guide, fuel model crosswalk, and set of fuel model photos are provided.

Estimating fire behavior with FIRECAST: user's manual

Treesearch

Jack D. Cohen

1986-01-01

FIRECAST is a computer program that estimates fire behavior in terms of six fire parameters. Required inputs vary depending on the outputs desired by the fire manager. Fuel model options available to users are these: Northern Forest Fire Laboratory (NFFL), National Fire Danger Rating System (NFDRS), and southern California brushland (SCAL). The program has been...

Modeling the effects of vegetation heterogeneity on wildland fire behavior

NASA Astrophysics Data System (ADS)

Atchley, A. L.; Linn, R.; Sieg, C.; Middleton, R. S.

2017-12-01

Vegetation structure and densities are known to drive fire-spread rate and burn severity. Many fire-spread models incorporate an average, homogenous fuel density in the model domain to drive fire behavior. However, vegetation communities are rarely homogenous and instead present significant heterogeneous structure and fuel densities in the fires path. This results in observed patches of varied burn severities and mosaics of disturbed conditions that affect ecological recovery and hydrologic response. Consequently, to understand the interactions of fire and ecosystem functions, representations of spatially heterogeneous conditions need to be incorporated into fire models. Mechanistic models of fire disturbance offer insight into how fuel load characterization and distribution result in varied fire behavior. Here we use a physically-based 3D combustion model—FIRETEC—that solves conservation of mass, momentum, energy, and chemical species to compare fire behavior on homogenous representations to a heterogeneous vegetation distribution. Results demonstrate the impact vegetation heterogeneity has on the spread rate, intensity, and extent of simulated wildfires thus providing valuable insight in predicted wildland fire evolution and enhanced ability to estimate wildland fire inputs into regional and global climate models.

High-fire-risk behavior in critical fire areas

Treesearch

William S. Folkman

1977-01-01

Observations of fire-related behavior of wildland visitors were made in three types of areas-wilderness, established campground, and built-up commercial and residential areas-within the San Bernardino National Forest, California. Interviews were conducted with all persons so observed. Types of fire-related behavior differed markedly from one area to another, as did the...

Repetitive deliberate fires: Development and validation of a methodology to detect series.

PubMed

Bruenisholz, Eva; Delémont, Olivier; Ribaux, Olivier; Wilson-Wilde, Linzi

2017-08-01

The detection of repetitive deliberate fire events is challenging and still often ineffective due to a case-by-case approach. A previous study provided a critical review of the situation and analysis of the main challenges. This study suggested that the intelligence process, integrating forensic data, could be a valid framework to provide a follow-up and systematic analysis provided it is adapted to the specificities of repetitive deliberate fires. In this current manuscript, a specific methodology to detect deliberate fires series, i.e. set by the same perpetrators, is presented and validated. It is based on case profiles relying on specific elements previously identified. The method was validated using a dataset of approximately 8000 deliberate fire events collected over 12 years in a Swiss state. Twenty possible series were detected, including 6 of 9 known series. These results are very promising and lead the way to a systematic implementation of this methodology in an intelligence framework, whilst demonstrating the need and benefit of increasing the collection of forensic specific information to strengthen the value of links between cases. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Fractographic study of the behavior of different ceramic veneers on full coverage crowns in relation to supporting core materials

PubMed Central

Agustín-Panadero, Rubén; Román-Rodriguez, Juan L.; Solá-Ruíz, María F.; Granell-Ruíz, María; Fons-Font, Antonio

2013-01-01

Objectives: To observe porcelain veneer behavior of zirconia and metal-ceramic full coverage crowns when subjected to compression testing, comparing zirconia cores to metal cores. Study Design: The porcelain fracture surfaces of 120 full coverage crowns (60 with a metal core and 60 with a zirconia core) subjected to static load (compression) testing were analyzed. Image analysis was performed using macroscopic processing with 8x and 12x enlargement. Five samples from each group were prepared and underwent scanning electron microscope (SEM) analysis in order to make a fractographic study of fracture propagation in the contact area and composition analysis in the most significant areas of the specimen. Results: Statistically significant differences in fracture type (cohesive or adhesive) were found between the metal-ceramic and zirconia groups: the incidence of adhesive fracture was seen to be greater in metal-ceramic groups (92%) and cohesive fracture was more frequent in zirconium oxide groups (72%). The fracture propagation pattern was on the periphery of the contact area in the full coverage crown restorations selected for fractographic study. Conclusions: The greater frequency of cohesive fracture in restorations with zirconia cores indicates that their behavior is inadequate compared to metal-ceramic restorations and that further research is needed to improve their clinical performance. Key words:Zirconia, zirconium oxide, fractography, composition, porcelain veneers, fracture, cohesive, adhesive. PMID:24455092

Responses of nestling black-crowned night herons (Nycticorax nycticorax) to aquatic and terrestrial recreational activities: a manipulative study

Treesearch

Esteban Fernandez-Juricic; Patrick A. Zollner; Cherie LeBlanc Fisher; Lynne M. Westphal

2007-01-01

We assessed the effects of the presence and the frequency of canoe and pedestrian disturbance during two breeding seasons on multiple behavioral responses (scanning, freezing, grooming, sleeping, moving, wing-raising, and standing-up) of Black-crowned Night Heron ( Nycticorax nycticorax ) nestlings in a breeding colony in southeast Chicago. Short-...

Fire danger index efficiency as a function of fuel moisture and fire behavior.

PubMed

Torres, Fillipe Tamiozzo Pereira; Romeiro, Joyce Machado Nunes; Santos, Ana Carolina de Albuquerque; de Oliveira Neto, Ricardo Rodrigues; Lima, Gumercindo Souza; Zanuncio, José Cola

2018-08-01

Assessment of the performance of forest fire hazard indices is important for prevention and management strategies, such as planning prescribed burnings, public notifications and firefighting resource allocation. The objective of this study was to evaluate the performance of fire hazard indices considering fire behavior variables and susceptibility expressed by the moisture of combustible material. Controlled burns were carried out at different times and information related to meteorological conditions, characteristics of combustible material and fire behavior variables were recorded. All variables analyzed (fire behavior and fuel moisture content) can be explained by the prediction indices. The Brazilian EVAP/P showed the best performance, both at predicting moisture content of the fuel material and fire behavior variables, and the Canadian system showed the best performance to predicting the rate of spread. The coherence of the correlations between the indices and the variables analyzed makes the methodology, which can be applied anywhere, important for decision-making in regions with no records or with only unreliable forest fire data. Copyright © 2018 Elsevier B.V. All rights reserved.

A ballistic evaluation of the impact resistance of spectacle lens materials.

PubMed

Oliver, A L; Chou, B R

1993-10-01

The impact resistance of chemically and thermally hardened glass lenses of 2.2- and 3.0-mm thicknesses was evaluated using a ballistic test. Each lens was edged and mounted into a spectacle frame, which was placed on a standard headform. A 6.5-mm steel ball was fired from an air gun at the center of the lens at increasing speeds until the lens broke. The multiple impact data were used to plot cumulative breakage curves. We found that heat-treated photochromic glass and heat-treated crown glass fail at similar missile speeds and that chemical treating considerably improves the impact resistance of crown glass but not of photochromic glass. The poorer performance of photochromic lenses indicates that they should not be prescribed when optimal impact protection is required. Plastic lenses show superior performance.

WRF-Fire: coupled weather-wildland fire modeling with the weather research and forecasting model

Treesearch

Janice L. Coen; Marques Cameron; John Michalakes; Edward G. Patton; Philip J. Riggan; Kara M. Yedinak

2012-01-01

A wildland fire behavior module (WRF-Fire) was integrated into the Weather Research and Forecasting (WRF) public domain numerical weather prediction model. The fire module is a surface fire behavior model that is two-way coupled with the atmospheric model. Near-surface winds from the atmospheric model are interpolated to a finer fire grid and used, with fuel properties...

Temporal scaling behavior of forest and urban fires

NASA Astrophysics Data System (ADS)

Wang, J.; Song, W.; Zheng, H.; Telesca, L.

2009-04-01

It has been found that many natural systems are characterized by scaling behavior. In such systems natural factors dominate the event dynamics. Forest fires in different countries have been found to exhibit frequency-size power law over many orders of magnitude and with similar value of parameters. But in countries with high population density such as China and Japan, more than 95% of the forest fire disasters are caused by human activities. Furthermore, with the development of society, the wildland-urban interface (WUI) area is becoming more and more populated, and the forest fire is much connected with urban fire. Therefore exploring the scaling behavior of fires dominated by human-related factors is very challenging. The present paper explores the temporal scaling behavior of forest fires and urban fires in Japan with mathematical methods. Two factors, Allan factor (AF) and Fano factor (FF) are used to investigate time-scaling of fire systems. It is found that the FF for both forest fires and urban fires increases linearly in log-log scales, and this indicates that it behaves as a power-law for all the investigated timescales. From the AF plot a 7 days cycle is found, which indicates a weekly cycle. This may be caused by human activities which has a weekly periodicity because on weekends people usually have more outdoor activities, which may cause more hidden trouble of fire disasters. Our findings point out that although the human factors are the main cause, both the forest fires and urban fires exhibit time-scaling behavior. At the same time, the scaling exponents for urban fires are larger than forest fires, signifying a more intense clustering. The reason may be that fires are affected not only by weather condition, but also by human activities, which play a more important role for urban fires than forest fires and have a power law distribution and scaling behavior. Then some work is done to the relative humidity. Similar distribution law characterizes the relative humidity. The AF plot and FF plot of relative humidity validate the existence of a strong link between weather and fires, and it is very likely that the daily humidity cycle determines the daily fire periodicity.

Ecological forestry in the Southeast: Understanding the ecology of fuels

Treesearch

R.J. Mitchell; J.K. Hiers; J. O’Brien; G. Starr

2009-01-01

Fire is a dominant disturbance within many forested ecosystems worldwide. Understanding the complex feedbacks among vegetation as a fuel for fire, the effects of fuels on fire behavior, and the impact of fire behavior on future vegetation are critical for sustaining biodiversity in fire-dependent forests. Nonetheless, understanding in fire ecology has been limited in...

An Overview of FlamMap Fire Modeling Capabilities

Treesearch

Mark A. Finney

2006-01-01

Computerized and manual systems for modeling wildland fire behavior have long been available (Rothermel 1983, Andrews 1986). These systems focus on one-dimensional behaviors and assume the fire geometry is a spreading line-fire (in contrast with point or area-source fires). Models included in these systems were developed to calculate fire spread rate (Rothermel 1972,...

Fire effects on basal area, tiller production, and mortality of the C4 Bunchgrass, Purple Threeawn

USDA-ARS?s Scientific Manuscript database

Fire behavior associated with wild and prescribed fires is variable, but plays a vital role in how a plant responds to fire. The relationship of fire behavior to rangeland plant community response has not been investigated, with a few exceptions, until recently. Fire is an important ecological pro...

Sensitivity of fire behavior simulations to fuel model variations

Treesearch

Lucy A. Salazar

1985-01-01

Stylized fuel models, or numerical descriptions of fuel arrays, are used as inputs to fire behavior simulation models. These fuel models are often chosen on the basis of generalized fuel descriptions, which are related to field observations. Site-specific observations of fuels or fire behavior in the field are not readily available or necessary for most fire management...

Solution Focused Empathy Training Groups for Students with Fire-Setting Behaviors

ERIC Educational Resources Information Center

Froeschle, Janet G.

2006-01-01

Fire-setting students are those who intentionally or unintentionally set one or more fires due to curiosity, stress, a need for attention, or due to criminal delinquency. This article describes the nature of fire-setting behaviors, discusses the profile and risk factors associated with the behavior, and outlines a group program using empathy…

[Research on the aging of all-ceramics restoration materials].

PubMed

Zhang, Dongjiao; Chen, Xinmin

2011-10-01

All-ceramic crowns and bridges have been widely used for dental restorations owing to their excellent functionality, aesthetics and biocompatibility. However, the premature clinical failure of all-ceramic crowns and bridges may easily occur when they are subjected to the complex environment of oral cavity. In the oral environment, all-ceramic materials are prone to aging. Aging can lead all-ceramic materials to change color, to lower bending strength, and to reduce anti-fracture toughness. There are many factors affecting the aging of the all-ceramic materials, for example, the grain size, the type of stabilizer, the residual stress and the water environment. In order to analyze the aging behavior, to optimize the design of all-ceramic crowns and bridges, and to evaluate the reliability and durability, we review in this paper recent research progress of aging behavior for all-ceramics restoration materials.

Uncertainty and risk in wildland fire management: A review

Treesearch

Matthew P. Thompson; Dave E. Calkin

2011-01-01

Wildland fire management is subject to manifold sources of uncertainty. Beyond the unpredictability of wildfire behavior, uncertainty stems from inaccurate/missing data, limited resource value measures to guide prioritization across fires and resources at risk, and an incomplete scientific understanding of ecological response to fire, of fire behavior response to...

How did prefire treatments affect the Biscuit Fire?

Treesearch

Crystal Raymond; David L. Peterson

2005-01-01

Most scientific literature supports forest thinning to reduce the severity of wildland fires, but the effectiveness of thinning in modifying fire behavior has not been well documented. The Biscuit Fire of 2002 offered a great opportunity to study the effects of mechanical thinning on fire behavior during a megafire.

Monthly fire behavior patterns

Treesearch

Mark J. Schroeder; Craig C. Chandler

1966-01-01

From tabulated frequency distributions of fire danger indexes for a nationwide network of 89 stations, the probabilities of four types of fire behavior ranging from 'fire out' to 'critical' were calculated for each month and are shown in map form.

Fire behavior, fuel treatments, and fire suppression on the Hayman Fire - Part 1: Fire weather, meteorology, and climate

Treesearch

Larry Bradshaw; Roberta Bartlette; John McGinely; Karl Zeller

2003-01-01

The Hayman Fire in June 2002 was heavily influenced by antecedent regional weather conditions, culminating in a series of daily weather events that aligned to produce widely varying fire behavior. This review of weather conditions associated with the Hayman Fire consists of two parts: 1) A brief overview of prior conditions as described by a regional climate review and...

Fire technology abstracts, volume 4. Cumulative indexes

NASA Astrophysics Data System (ADS)

1982-03-01

Cumulative subject, author, publisher, and report number indexes referencing articles, books, reports, and patents are provided. The dynamics of fire, behavior and properties of materials, fire modeling and test burns, fire protection, fire safety, fire service organization, apparatus and equipment, fire prevention suppression, planning, human behavior, medical problems, codes and standards, hazard identification, safe handling of materials, and insurance economics of loss and prevention are among the subjects covered.

Field procedures for verification and adjustment of fire behavior predictions

Treesearch

Richard C. Rothermel; George C. Rinehart

1983-01-01

The problem of verifying predictions of fire behavior, primarily rate of spread, is discussed in terms of the fire situation for which predictions are made, and the type of fire where data are to be collected. Procedures for collecting data and performing analysis are presented for both readily accessible fires where data should be complete, and for inaccessible fires...

BehavePlus fire modeling system, version 5.0: Design and Features

Treesearch

Faith Ann Heinsch; Patricia L. Andrews

2010-01-01

The BehavePlus fire modeling system is a computer program that is based on mathematical models that describe wildland fire behavior and effects and the fire environment. It is a flexible system that produces tables, graphs, and simple diagrams. It can be used for a host of fire management applications, including projecting the behavior of an ongoing fire, planning...

Simulation of quaking aspen potential fire behavior in Northern Utah, USA

Treesearch

R. Justin DeRose; A. Joshua Leffler

2014-01-01

Current understanding of aspen fire ecology in western North America includes the paradoxical characterization that aspen-dominated stands, although often regenerated following fire, are “fire-proof”. We tested this idea by predicting potential fire behavior across a gradient of aspen dominance in northern Utah using the Forest Vegetation Simulator and the Fire and...

An evaluation of The Great Escape: can an interactive computer game improve young children's fire safety knowledge and behaviors?

PubMed

Morrongiello, Barbara A; Schwebel, David C; Bell, Melissa; Stewart, Julia; Davis, Aaron L

2012-07-01

Fire is a leading cause of unintentional injury and, although young children are at particularly increased risk, there are very few evidence-based resources available to teach them fire safety knowledge and behaviors. Using a pre-post randomized design, the current study evaluated the effectiveness of a computer game (The Great Escape) for teaching fire safety information to young children (3.5-6 years). Using behavioral enactment procedures, children's knowledge and behaviors related to fire safety were compared to a control group of children before and after receiving the intervention. The results indicated significant improvements in knowledge and fire safety behaviors in the intervention group but not the control. Using computer games can be an effective way to promote young children's understanding of safety and how to react in different hazardous situations.

A mixed integer program to model spatial wildfire behavior and suppression placement decisions

Treesearch

Erin J. Belval; Yu Wei; Michael Bevers

2015-01-01

Wildfire suppression combines multiple objectives and dynamic fire behavior to form a complex problem for decision makers. This paper presents a mixed integer program designed to explore integrating spatial fire behavior and suppression placement decisions into a mathematical programming framework. Fire behavior and suppression placement decisions are modeled using...

Fire weather and behavior of the Little Sioux fire.

Treesearch

Rodney W. Sando; Donald A. Haines

1972-01-01

In mid-May 1971, a northern Minnesota fire burned almost 15,000 acres of forest land. The extreme fire behavior it exhibited was the product of a number of described features. This paper documents the attendant fuel and weather conditions.

Digital evaluation of the fit of zirconia-reinforced lithium silicate crowns with a new three-dimensional approach.

PubMed

Zimmermann, Moritz; Valcanaia, Andre; Neiva, Gisele; Mehl, Albert; Fasbinder, Dennis

2017-11-30

Several methods for the evaluation of fit of computer-aided design/computer-assisted manufacture (CAD/CAM)-fabricated restorations have been described. In the study, digital models were recorded with an intraoral scanning device and were measured using a new three-dimensional (3D) computer technique to evaluate restoration internal fit. The aim of the study was to evaluate the internal adaptation and fit of chairside CAD/CAM-fabricated zirconia-reinforced lithium silicate ceramic crowns fabricated with different post-milling protocols. The null hypothesis was that different post-milling protocols did not influence the fitting accuracy of zirconia-reinforced lithium silicate restorations. A master all-ceramic crown preparation was completed on a maxillary right first molar on a typodont. Twenty zirconia-reinforced lithium silicate ceramic crowns (Celtra Duo, Dentsply Sirona) were designed and milled using a chairside CAD/CAM system (CEREC Omnicam, Dentsply Sirona). The 20 crowns were randomly divided into two groups based on post-milling protocols: no manipulation after milling (Group MI) and oven fired-glazing after milling (Group FG). A 3D computer method was used to evaluate the internal adaptation of the crowns. This was based on a subtractive analysis of a digital scan of the crown preparation and a digital scan of the thickness of the cement space over the crown preparation as recorded by a polyvinylsiloxane (PVS) impression material. The preparation scan and PVS scan were matched in 3D and a 3D difference analysis was performed with a software program (OraCheck, Cyfex). Three areas of internal adaptation and fit were selected for analysis: margin (MA), axial wall (AX), and occlusal surface (OC). Statistical analysis was performed using 80% percentile and one-way ANOVA with post-hoc Scheffé test (P = .05). The closest internal adaptation of the crowns was measured at the axial wall with 102.0 ± 11.7 µm for group MI-AX and 106.3 ± 29.3 µm for group FG-AX. The largest internal adaptation of the crowns was measured for the occlusal surface with 258.9 ± 39.2 µm for group MI-OC and 260.6 ± 55.0 µm for group FG-OC. No statistically significant differences were found for the post-milling protocols (P > .05). The 3D difference pattern was visually analyzed for each area with a color-coded scheme. Post-milling processing did not affect the internal adaptation of zirconia-reinforced lithium silicate crowns fabricated with a chairside CAD/CAM technique. The new 3D computer technique for the evaluation of fit of restorations may be highly promising and has the opportunity to be applied to clinical studies.

A grass-fire cycle eliminates an obligate-seeding tree in a tropical savanna.

PubMed

Bowman, David M J S; MacDermott, Harry J; Nichols, Scott C; Murphy, Brett P

2014-11-01

A grass-fire cycle in Australian tropical savannas has been postulated as driving the regional decline of the obligate-seeding conifer Callitris intratropica and other fire-sensitive components of the regional flora and fauna, due to proliferation of flammable native grasses. We tested the hypothesis that a high-biomass invasive savanna grass drives a positive feedback process where intense fires destroy fire-sensitive trees, and the reduction in canopy cover facilitates further invasion by grass. We undertook an observational and experimental study using, as a model system, a plantation of C. intratropica that has been invaded by an African grass, gamba (Andropogon gayanus) in the Northern Territory, Australia. We found that high grass biomass was associated with reduced canopy cover and restriction of foliage to the upper canopy of surviving stems, and mortality of adult trees was very high (>50%) even in areas with low fuel loads (1 t·ha(-1)). Experimental fires, with fuel loads >10 t·ha(-1), typical of the grass-invasion front, caused significant mortality due to complete crown scorch. Lower fuel loads cause reduced canopy cover through defoliation of the lower canopy. These results help explain how increases in grass biomass are coupled with the decline of C. intratropica throughout northern Australia by causing a switch from litter and sparse perennial grass fuels, and hence low-intensity surface fires, to heavy annual grass fuel loads that sustain fires that burn into the midstorey. This study demonstrates that changes in fuel type can alter fire regimes with substantial knock-on effects on the biota.

A grass–fire cycle eliminates an obligate-seeding tree in a tropical savanna

PubMed Central

Bowman, David M J S; MacDermott, Harry J; Nichols, Scott C; Murphy, Brett P

2014-01-01

A grass–fire cycle in Australian tropical savannas has been postulated as driving the regional decline of the obligate-seeding conifer Callitris intratropica and other fire-sensitive components of the regional flora and fauna, due to proliferation of flammable native grasses. We tested the hypothesis that a high-biomass invasive savanna grass drives a positive feedback process where intense fires destroy fire-sensitive trees, and the reduction in canopy cover facilitates further invasion by grass. We undertook an observational and experimental study using, as a model system, a plantation of C. intratropica that has been invaded by an African grass, gamba (Andropogon gayanus) in the Northern Territory, Australia. We found that high grass biomass was associated with reduced canopy cover and restriction of foliage to the upper canopy of surviving stems, and mortality of adult trees was very high (>50%) even in areas with low fuel loads (1 t·ha−1). Experimental fires, with fuel loads >10 t·ha−1, typical of the grass-invasion front, caused significant mortality due to complete crown scorch. Lower fuel loads cause reduced canopy cover through defoliation of the lower canopy. These results help explain how increases in grass biomass are coupled with the decline of C. intratropica throughout northern Australia by causing a switch from litter and sparse perennial grass fuels, and hence low-intensity surface fires, to heavy annual grass fuel loads that sustain fires that burn into the midstorey. This study demonstrates that changes in fuel type can alter fire regimes with substantial knock-on effects on the biota. PMID:25505543

Evaluating potential fire behavior in lodgepole pine-dominated forests after a mountain pine beetle epidemic in north-central Colorado

Treesearch

Jennifer G. Klutsch; Mike A. Battaglia; Daniel R. West; Sheryl L. Costello; Jose F. Negron

2011-01-01

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...

Viscoelastic finite element analysis of residual stresses in porcelain-veneered zirconia dental crowns.

PubMed

Kim, Jeongho; Dhital, Sukirti; Zhivago, Paul; Kaizer, Marina R; Zhang, Yu

2018-06-01

The main problem of porcelain-veneered zirconia (PVZ) dental restorations is chipping and delamination of veneering porcelain owing to the development of deleterious residual stresses during the cooling phase of veneer firing. The aim of this study is to elucidate the effects of cooling rate, thermal contraction coefficient and elastic modulus on residual stresses developed in PVZ dental crowns using viscoelastic finite element methods (VFEM). A three-dimensional VFEM model has been developed to predict residual stresses in PVZ structures using ABAQUS finite element software and user subroutines. First, the newly established model was validated with experimentally measured residual stress profiles using Vickers indentation on flat PVZ specimens. An excellent agreement between the model prediction and experimental data was found. Then, the model was used to predict residual stresses in more complex anatomically-correct crown systems. Two PVZ crown systems with different thermal contraction coefficients and porcelain moduli were studied: VM9/Y-TZP and LAVA/Y-TZP. A sequential dual-step finite element analysis was performed: heat transfer analysis and viscoelastic stress analysis. Controlled and bench convection cooling rates were simulated by applying different convective heat transfer coefficients 1.7E-5 W/mm 2 °C (controlled cooling) and 0.6E-4 W/mm 2 °C (bench cooling) on the crown surfaces exposed to the air. Rigorous viscoelastic finite element analysis revealed that controlled cooling results in lower maximum stresses in both veneer and core layers for the two PVZ systems relative to bench cooling. Better compatibility of thermal contraction coefficients between porcelain and zirconia and a lower porcelain modulus reduce residual stresses in both layers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fire behavior simulation in Mediterranean forests using the minimum travel time algorithm

Treesearch

Kostas Kalabokidis; Palaiologos Palaiologou; Mark A. Finney

2014-01-01

Recent large wildfires in Greece exemplify the need for pre-fire burn probability assessment and possible landscape fire flow estimation to enhance fire planning and resource allocation. The Minimum Travel Time (MTT) algorithm, incorporated as FlamMap's version five module, provide valuable fire behavior functions, while enabling multi-core utilization for the...

Appraising fuels and flammability in western aspen: a prescribed fire guide

Treesearch

James K. Brown; Dennis G. Simmerman

1986-01-01

Describes a method for appraising fuels and fire behavior potential in aspen forests to guide the use of prescribed fire and the preparation of fire prescriptions. Includes an illustrated classification of aspen fuels; appraisals of fireline intensity, rate of spread, adjective ratings for fire behavior and probability of burn success; and evaluations of seasonal...

Davis Fire: Fire behavior and fire effects analysis

Treesearch

LaWen T. Hollingsworth

2010-01-01

The Davis Fire presents an interesting example of fire behavior in subalpine fir, partially dead lodgepole pine with multiple age classes, and moist site Douglas-fir vegetation types. This has been summer of moderate temperatures and intermittent moisture that has kept live herbaceous and live woody moistures fairly high and dead fuel moistures at a moderate level....

Fatigue behavior of resin-modified monolithic CAD-CAM RNC crowns and endocrowns.

PubMed

Rocca, G T; Sedlakova, P; Saratti, C M; Sedlacek, R; Gregor, L; Rizcalla, N; Feilzer, A J; Krejci, I

2016-12-01

To evaluate the influence of different types of modifications with resin on fatigue resistance and failure behavior of CAD-CAM resin nano ceramic (RNC) restorations for maxillary first premolars. Sixty standardized resin composite root dies received CAD-CAM RNC endocrowns (n=30) and crowns (n=30) (Lava Ultimate, 3M Espe). Restorations were divided into six groups: full anatomic endocrowns (group A) and crowns (group D), buccal resin veneered endocrowns (group B) and crowns (group E) and buccal resin veneered endocrowns (group C) and crowns (group F) with a central groove resin filling. A nano-hybrid resin composite was used to veneer the restorations (Filtek Supreme, 3M Espe). All specimens were first submitted to thermo-mechanical cyclic loading (1.7Hz, 49N, 600000 cycles, 1500 thermo-cycles) and then submitted to cyclic isometric stepwise loading (5Hz) until completion of 105000 cycles or failure after 5000 cycles at 200N, followed by 20000 cycles at 400N, 600N, 800N, 1000N and 1200N. In case of fracture, fragments were analyzed using SEM and modes of failure were determined. Results were statistically analyzed by Kaplan-Meier life survival analysis and log rank test (p=0.05). The differences in survival between groups were not statistically significant, except between groups D and F (p=0.039). Endocrowns fractured predominantly with a mesio-distal wedge-opening fracture (82%). Partial cusp fractures were observed above all in crowns (70%). Analysis of the fractured specimens revealed that the origin of the fracture was mainly at the occlusal contact points of the stepwise loading. Veneering of CAD-CAM RNC restorations has no influence on their fatigue resistance except when monolithic crowns are modified on their occlusal central groove. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Pre-outbreak forest conditions mediate the effects of spruce beetle outbreaks on fuels in subalpine forests of Colorado.

PubMed

Mietkiewicz, Nathan; Kulakowski, Dominik; Veblen, Thomas T

2018-03-01

Over the past 30 years, forest disturbances have increased in size, intensity, and frequency globally, and are predicted to continue increasing due to climate change, potentially relaxing the constraints of vegetation properties on disturbance regimes. However, the consequences of the potentially declining importance of vegetation in determining future disturbance regimes are not well understood. Historically, bark beetles preferentially attack older trees and stands in later stages of development. However, as climate warming intensifies outbreaks by promoting growth of beetle populations and compromising tree defenses, smaller diameter trees and stands in early stages of development now are being affected by outbreaks. To date, no study has considered how stand age and other pre-outbreak forest conditions mediate the effects of outbreaks on surface and aerial fuel arrangements. We collected fuels data across a chronosequence of post-outbreak sites affected by spruce beetle (SB) between the 1940s and the 2010s, stratified by young (<130 yr) and old (>130 yr) post-fire stands. Canopy and surface fuel loads were calculated for each tree and stand, and available crown fuel load, crown bulk density, and canopy bulk densities were estimated. Canopy bulk density and density of live canopy individuals were reduced in all stands affected by SB, though foliage loss was proportionally greater in old stands as compared to young stands. Fine surface fuel loads in young stands were three times greater shortly (<30 yr) following outbreak as compared to young stands not affected by outbreak, after which the abundance of fine surface fuels decreased to below endemic (i.e., non-outbreak) levels. In both young and old stands, the net effect of SB outbreaks during the 20th and 21st centuries reduced total canopy fuels and increased stand-scale spatial heterogeneity of canopy fuels following outbreak. Importantly, the decrease in canopy fuels following outbreaks was greater in young post-fire stands than in older stands, suggesting that SB outbreaks may more substantially reduce risk of active crown fire when they affect stands in earlier stages of development. The current study shows that the effects of SB outbreaks on forest structure and on fuel profiles are strongly contingent on pre-outbreak conditions as determined by pre-outbreak disturbance history. © 2018 by the Ecological Society of America.

Effect of the infrastructure material on the failure behavior of prosthetic crowns.

PubMed

Sonza, Queli Nunes; Della Bona, Alvaro; Borba, Márcia

2014-05-01

To evaluate the effect of infrastructure (IS) material on the fracture behavior of prosthetic crowns. Restorations were fabricated using a metal die simulating a prepared tooth. Four groups were evaluated: YZ-C, Y-TZP (In-Ceram YZ, Vita) IS produced by CAD-CAM; IZ-C, In-Ceram Zirconia (Vita) IS produced by CAD-CAM; IZ-S, In-Ceram Zirconia (Vita) IS produced by slip-cast; MC, metal IS (control). The IS were veneered with porcelain and resin cemented to fiber-reinforced composite dies. Specimens were loaded in compression to failure using a universal testing machine. The 30° angle load was applied by a spherical piston, in 37°C distilled water. Fractography was performed using stereomicroscope and SEM. Data were statistically analyzed with Anova and Student-Newman-Keuls tests (α=0.05). Significant differences were found between groups (p=0.022). MC showed the highest mean failure load, statistically similar to YZ-C. There was no statistical difference between YZ-C, IZ-C and IZ-S. MC and YZ-C showed no catastrophic failure. IZ-C and IZ-S showed chipping and catastrophic failures. The fracture behavior is similar to reported clinical failures. Considering the ceramic systems evaluated, YZ-C and MC crowns present greater fracture load and a more favorable failure mode than In-Ceram Zirconia crowns, regardless of the fabrication type (CAD-CAM or slip-cast). Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The effectiveness and limitations of fuel modeling using the fire and fuels extension to the Forest Vegetation Simulator

Treesearch

Erin K. Noonan-Wright; Nicole M. Vaillant; Alicia L. Reiner

2014-01-01

Fuel treatment effectiveness is often evaluated with fire behavior modeling systems that use fuel models to generate fire behavior outputs. How surface fuels are assigned, either using one of the 53 stylized fuel models or developing custom fuel models, can affect predicted fire behavior. We collected surface and canopy fuels data before and 1, 2, 5, and 8 years after...

BEHAVE: fire behavior prediction and fuel modeling system-BURN Subsystem, part 1

Treesearch

Patricia L. Andrews

1986-01-01

Describes BURN Subsystem, Part 1, the operational fire behavior prediction subsystem of the BEHAVE fire behavior prediction and fuel modeling system. The manual covers operation of the computer program, assumptions of the mathematical models used in the calculations, and application of the predictions.

Temporal and spatial variations in microclimate influence the larval foraging behaviors and performance of a conifer-feeding sawfly.

PubMed

Johns, R C; Boone, J; Leggo, J J; Smith, S; Carleton, D; Quiring, D T

2012-06-01

Herbivorous insects are often exposed to broad temporal and spatial variations in microclimate conditions within their host plants and have adapted a variety of behaviors, such as avoidance or basking, to either offset or benefit from such variation. Field experiments were carried out to investigate the influence of daily and intratree variations in microclimate on the behaviors (feeding, resting, dispersal, and hiding) and associated performance of late-instar larvae of the yellowheaded spruce sawfly, Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae) within crowns of 1.25-1.5 m tall black spruce (Picea mariana [Miller] Britton Sterns Poggenburg); late instars feed on developing shoots of young spruce and are often exposed to microclimatic extremes with unknown effects on performance. Larvae fed diurnally from just after dawn (0800 h) until dusk (2000 h) and rested throughout the night, with brief periods of dispersal occurring in the morning and evening. Neither larval behavior nor abiotic conditions differed significantly between the upper and lower crowns of trees. Temperature, humidity, and solar insolation all explained >90% of variation in feeding; however, sunrise and sunset were the most likely cues influencing diurnal behavior. Most larvae (94%) fed on the bottom, shaded side of shoots, and field experiments indicated that this behavior is adaptive with respect to microclimate, probably reducing hygrothermal stress. Thus, behavioral adaptations by P. alaskensis to daily and within-shoot microclimatic variation may reduce the risk of hygrothermal stress during dispersal or feeding, while still allowing larvae to feed on the preferred and highly nutritious upper crown foliage of young spruce.

A population model of chaparral vegetation response to frequent wildfires.

PubMed

Lucas, Timothy A; Johns, Garrett; Jiang, Wancen; Yang, Lucie

2013-12-01

The recent increase in wildfire frequency in the Santa Monica Mountains (SMM) may substantially impact plant community structure. Species of Chaparral shrubs represent the dominant vegetation type in the SMM. These species can be divided into three life history types according to their response to wildfires. Nonsprouting species are completely killed by fire and reproduce by seeds that germinate in response to a fire cue, obligate sprouting species survive by resprouting from dormant buds in a root crown because their seeds are destroyed by fire, and facultative sprouting species recover after fire both by seeds and resprouts. Based on these assumptions, we developed a set of nonlinear difference equations to model each life history type. These models can be used to predict species survivorship under varying fire return intervals. For example, frequent fires can lead to localized extinction of nonsprouting species such as Ceanothus megacarpus while several facultative sprouting species such as Ceanothus spinosus and Malosma (Rhus) laurina will persist as documented by a longitudinal study in a biological preserve in the SMM. We estimated appropriate parameter values for several chaparral species using 25 years of data and explored parameter relationships that lead to equilibrium populations. We conclude by looking at the survival strategies of these three species of chaparral shrubs under varying fire return intervals and predict changes in plant community structure under fire intervals of short return. In particular, our model predicts that an average fire return interval of greater than 12 years is required for 50 % of the initial Ceanothus megacarpus population and 25 % of the initial Ceanothus spinosus population to survive. In contrast, we predict that the Malosma laurina population will have 90 % survivorship for an average fire return interval of at least 6 years.

Flame retardants in UK furniture increase smoke toxicity more than they reduce fire growth rate.

PubMed

McKenna, Sean T; Birtles, Robert; Dickens, Kathryn; Walker, Richard G; Spearpoint, Michael J; Stec, Anna A; Hull, T Richard

2018-04-01

This paper uses fire statistics to show the importance of fire toxicity on fire deaths and injuries, and the importance of upholstered furniture and bedding on fatalities from unwanted fires. The aim was to compare the fire hazards (fire growth and smoke toxicity) using different upholstery materials. Four compositions of sofa-bed were compared: three meeting UK Furniture Flammability Regulations (FFR), and one using materials without flame retardants intended for the mainland European market. Two of the UK sofa-beds relied on chemical flame retardants to meet the FFR, the third used natural materials and a technical weave in order to pass the test. Each composition was tested in the bench-scale cone calorimeter (ISO 5660) and burnt as a whole sofa-bed in a sofa configuration in a 3.4 × 2.25 × 2.4 m 3 test room. All of the sofas were ignited with a No. 7 wood crib; the temperatures and yields of toxic products are reported. The sofa-beds containing flame retardants burnt somewhat more slowly than the non-flame retarded EU sofa-bed, but in doing so produced significantly greater quantities of the main fire toxicants, carbon monoxide and hydrogen cyanide. Assessment of the effluents' potential to incapacitate and kill is provided showing the two UK flame retardant sofa-beds to be the most dangerous, followed by the sofa-bed made with European materials. The UK sofa-bed made only from natural materials (Cottonsafe ® ) burnt very slowly and produced very low concentrations of toxic gases. Including fire toxicity in the FFR would reduce the chemical flame retardants and improve fire safety. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Assessment of the FARSITE model for predicting fire behavior in the Southern Appalachian Mountains

Treesearch

Ross J. Phillips; Thomas A. Waldrop; Dean M. Simon

2006-01-01

Fuel reduction treatments are necessary in fire-adapted ecosystems where fire has been excluded for decades and the potential for severe wildfire is high. Using the Fire Area Simulator, FARSITE, we examined the spatial and temporal effects of these treatments on fire behavior in the Southern Appalachian Mountains. With measurements from temperature sensors during...

An uncommon case of random fire-setting behavior associated with Todd paralysis: a case report.

PubMed

Kanehisa, Masayuki; Morinaga, Katsuhiko; Kohno, Hisae; Maruyama, Yoshihiro; Ninomiya, Taiga; Ishitobi, Yoshinobu; Tanaka, Yoshihiro; Tsuru, Jusen; Hanada, Hiroaki; Yoshikawa, Tomoya; Akiyoshi, Jotaro

2012-08-31

The association between fire-setting behavior and psychiatric or medical disorders remains poorly understood. Although a link between fire-setting behavior and various organic brain disorders has been established, associations between fire setting and focal brain lesions have not yet been reported. Here, we describe the case of a 24-year-old first time arsonist who suffered Todd's paralysis prior to the onset of a bizarre and random fire-setting behavior. A case of a 24-year-old man with a sudden onset of a bizarre and random fire-setting behavior is reported. The man, who had been arrested on felony arson charges, complained of difficulties concentrating and of recent memory disturbances with leg weakness. A video-EEG recording demonstrated a close relationship between the focal motor impairment and a clear-cut epileptic ictal discharge involving the bilateral motor cortical areas. The SPECT result was statistically analyzed by comparing with standard SPECT images obtained from our institute (easy Z-score imaging system; eZIS). eZIS revealed hypoperfusion in cingulate cortex, basal ganglia and hyperperfusion in frontal cortex,. A neuropsychological test battery revealed lower than normal scores for executive function, attention, and memory, consistent with frontal lobe dysfunction. The fire-setting behavior and Todd's paralysis, together with an unremarkable performance on tests measuring executive function fifteen months prior, suggested a causal relationship between this organic brain lesion and the fire-setting behavior. The case describes a rare and as yet unreported association between random, impulse-driven fire-setting behavior and damage to the brain and suggests a disconnection of frontal lobe structures as a possible pathogenic mechanism.

Prevalence and correlates of fire-setting in the United States: results from the National Epidemiological Survey on Alcohol and Related Conditions.

PubMed

Vaughn, Michael G; Fu, Qiang; Delisi, Matt; Wright, John Paul; Beaver, Kevin M; Perron, Brian E; Howard, Matthew O

2010-01-01

Fire-setting is a serious and costly form of antisocial behavior. Our objective in this study was to examine the prevalence and correlates of intentional fire-setting behavior in the United States. Data were derived from a nationally representative sample of US residents 18 years and older. Structured psychiatric interviews (N = 43,093) were completed by trained lay interviewers between 2001 and 2002. Fire-setting as well as mood, anxiety, substance use, and personality disorders of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition were assessed with the Alcohol Use Disorder and Associated Disabilities Interview Schedule (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) version. The prevalence of lifetime fire-setting in the US population was 1.0%. Respondents who were men, white, 18 to 35 years old, born in the United States, and living in the western region of the United States had significantly higher rates of fire-setting than their counterparts. Fire-setting was significantly associated with a wide range of antisocial behaviors. Multivariate logistic regression analyses identified strong associations between lifetime alcohol and marijuana use disorders, conduct disorder, antisocial and obsessive-compulsive personality disorders, and family history of antisocial behavior. Intentional illicit fire-setting behavior is associated with a broad array of antisocial behaviors and psychiatric comorbidities. Given the substantial personal and social costs related to arson, prevention and treatment interventions targeting fire-setters potentially could save lives and property. 2010 Elsevier Inc. All rights reserved.

Does fire severity influence shrub resprouting after spring prescribed burning?

NASA Astrophysics Data System (ADS)

Fernández, Cristina; Vega, José A.; Fonturbel, Teresa

2013-04-01

Prescribed burning is commonly used to reduce the risk of severe wildfire. However, further information about the associated environmental effects is required to help forest managers select the most appropriate treatment. To address this question, we evaluated if fire severity during spring prescribed burning significantly affects the resprouting ability of two common shrub species in shrubland under a Mediterranean climate in NW Spain. Fire behaviour and temperatures were recorded in tagged individuals of Erica australis and Pterospartum tridentatum during prescribed burning. The number and length of resprouted shoots were measured three times (6, 12 and 18 months) after the prescribed burning. The influence of a series of fire severity indicators on some plant resprouting vigour parameters was tested by canonical correlation analysis. Six months and one year after prescribed burning, soil burn severity (measured by the absolute reduction in depth of the organic soil layer, maximum temperatures in the organic soil layer and the mineral soil surface during burning and the post-fire depth of the organic soil layer) reduced the resprouting vigour of E. australis and P. tridentatum. In contrast, direct measurements of fire effects on plants (minimum branch diameter, duration of temperatures above 300 °C in the shrub crown and fireline intensity) did not affect the post-fire plant vigour. Soil burn severity during spring prescribed burning significantly affected the short-term resprouting vigour in a mixed heathland in Galicia. The lack of effects eighteen months after prescribed burning indicates the high resilience of these species and illustrates the need to conciliate fire prevention and conservation goals.

Variation in fire regimes of the Rocky Mountains: Implications for avian communities and fire management

USGS Publications Warehouse

Saab, Victoria A.; Powell, Hugo D.W.; Kotliar, Natasha B.; Newlon, Karen R.; Saab, Victoria A.; Powell, Hugo D.W.

2005-01-01

Information about avian responses to fire in the U.S. Rocky Mountains is based solely on studies of crown fires. However, fire management in this region is based primarily on studies of low-elevation ponderosa pine (Pinus ponderosa) forests maintained largely by frequent understory fires. In contrast to both of these trends, most Rocky Mountain forests are subject to mixed severity fire regimes. As a result, our knowledge of bird responses to fire in the region is incomplete and skewed toward ponderosa pine forests. Research in recent large wildfires across the Rocky Mountains indicates that large burns support diverse avifauna. In the absence of controlled studies of bird responses to fire, we compared reproductive success for six cavity-nesting species using results from studies in burned and unburned habitats. Birds in ponderosa pine forests burned by stand-replacement fire tended to have higher nest success than individuals of the same species in unburned habitats, but unburned areas are needed to serve species dependent upon live woody vegetation, especially foliage gleaners. Over the last century, fire suppression, livestock grazing, and logging altered the structure and composition of many low-elevation forests, leading to larger and more severe burns. In higher elevation forests, changes have been less marked. Traditional low-severity prescribed fire is not likely to replicate historical conditions in these mixed or high-severity fire regimes, which include many mixed coniferous forests and all lodgepole pine (Pinus contorta) and spruce-fi r (Picea-Abies) forests. We suggest four research priorities: (1) the effects of fire severity and patch size on species’ responses to fire, (2) the possibility that postfire forests are ephemeral sources for some bird species, (3) the effect of salvage logging prescriptions on bird communities, and (4) experiments that illustrate bird responses to prescribed fire and other forest restoration methods. This research is urgent if we are to develop fire management strategies that reduce fire risk and maintain habitat for avifauna and other wildlife of the Rocky Mountains.

Variation in fire regimes of the rocky mountains: Implications for avian communities and fire management

USGS Publications Warehouse

Saab, V.A.; Powell, Hugo D.W.; Kotliar, N.B.; Newlon, K.R.

2005-01-01

Information about avian responses to fire in the U.S. Rocky Mountains is based solely on studies of crown fires. However, fire management in this region is based primarily on studies of low-elevation ponderosa pine (Pinus ponderosa) forests maintained largely by frequent understory fires. In contrast to both of these trends, most Rocky Mountain forests are subject to mixed severity fire regimes. As a result, our knowledge of bird responses to fire in the region is incomplete and skewed toward ponderosa pine forests. Research in recent large wildfires across the Rocky Mountains indicates that large burns support diverse avifauna. In the absence of controlled studies of bird responses to fire, we compared reproductive success for six cavity-nesting species using results from studies in burned and unburned habitats. Birds in ponderosa pine forests burned by stand-replacement fire tended to have higher nest success than individuals of the same species in unburned habitats, but unburned areas are needed to serve species dependent upon live woody vegetation, especially foliage gleaners. Over the last century, fire suppression, livestock grazing, and logging altered the structure and composition of many low-elevation forests, leading to larger and more severe burns. In higher elevation forests, changes have been less marked. Traditional low-severity prescribed fire is not likely to replicate historical conditions in these mixed or high-severity fire regimes, which include many mixed coniferous forests and all lodgepole pine (Pinus contorta) and spruce-fir (Picea-Abies) forests. We suggest four research priorities: (1) the effects of fire severity and patch size on species' responses to fire, (2) the possibility that postfire forests are ephemeral sources for some bird species, (3) the effect of salvage logging prescriptions on bird communities, and (4) experiments that illustrate bird responses to prescribed fire and other forest restoration methods. This research is urgent if we are to develop fire management strategies that reduce fire risk and maintain habitat for avifauna and other wildlife of the Rocky Mountains.

Fire-induced changes in boreal forest canopy volume and soil organic matter from multi-temporal airborne lidar

NASA Astrophysics Data System (ADS)

Alonzo, M.; Cook, B.; Andersen, H. E.; Babcock, C. R.; Morton, D. C.

2016-12-01

Fire in boreal forests initiates a cascade of biogeochemical and biophysical processes. Over typical fire return intervals, net radiative forcing from boreal forest fires depends on the offsetting impacts of greenhouse gas emissions and post-fire changes in land surface albedo. Whether boreal forest fires warm or cool the climate over these multi-decadal intervals depends on the magnitude of fire emissions and the time scales of decomposition, albedo changes, and forest regrowth. Our understanding of vegetation and surface organic matter (SOM) changes from boreal forest fires is shaped by field measurements and moderate resolution remote sensing data. Intensive field plot measurements offer detailed data on overstory, understory, and SOM changes from fire, but sparse plot data can be difficult to extend across the heterogeneous boreal forest landscape. Conversely, satellite measurements of burn severity are spatially extensive but only provide proxy measures of fire effects. In this research, we seek to bridge the scale gap between existing intensive and extensive methods using a combination of airborne lidar data and time series of Landsat data to evaluate pre- and post-fire conditions across Alaska's Kenai Peninsula. Lidar-based estimates of pre-fire stand structure and composition were essential to characterize the loss of canopy volume from fires between 2001 and 2014, quantify transitions from live to dead standing carbon pools, and isolate vegetation recovery following fire over 1 to 13 year time scales. Results from this study demonstrate the utility of lidar for estimating pre-fire structure and species composition at the scale of individual tree crowns. Multi-temporal airborne lidar data also provide essential insights regarding the heterogeneity of canopy and SOM losses at a sub-Landsat pixel scale. Fire effects are forest-structure and species dependent with variable temporal lags in carbon release due to delayed mortality (>5 years post fire) and standing dead trees. Establishing the spatial and temporal scales of canopy structural change will aid in constraining estimates of net radiative forcing from both carbon release and albedo in the years following fire.

Validation of BEHAVE fire behavior predictions in oak savannas using five fuel models

Treesearch

Keith Grabner; John Dwyer; Bruce Cutter

1997-01-01

Prescribed fire is a valuable tool in the restoration and management of oak savannas. BEHAVE, a fire behavior prediction system developed by the United States Forest Service, can be a useful tool when managing oak savannas with prescribed fire. BEHAVE predictions of fire rate-of-spread and flame length were validated using four standardized fuel models: Fuel Model 1 (...

Fire behavior sensor package remote trigger design

Treesearch

Dan Jimenez; Jason Forthofer; James Reardon; Bret Butler

2007-01-01

Fire behavior characteristics (such as temperature, radiant and total heat flux, 2- and 3-dimensional velocities, and air flow) are extremely difficult to measure insitu. Although insitu sensor packages are capable of such measurements in realtime, it is also essential to acquire video documentation as a means of better understanding the fire behavior data recorded by...

The simulation of surface fire spread based on Rothermel model in windthrow area of Changbai Mountain (Jilin, China)

NASA Astrophysics Data System (ADS)

Yin, Hang; Jin, Hui; Zhao, Ying; Fan, Yuguang; Qin, Liwu; Chen, Qinghong; Huang, Liya; Jia, Xiang; Liu, Lijie; Dai, Yuhong; Xiao, Ying

2018-03-01

The forest-fire not only brings great loss to natural resources, but also destructs the ecosystem and reduces the soil fertility, causing some natural disasters as soil erosion and debris flow. However, due to the lack of the prognosis for forest fire spreading trend in forest fire fighting, it is difficult to formulate rational and effective fire-fighting scheme. In the event of forest fire, achieving accurate judgment to the fire behavior would greatly improve the fire-fighting efficiency, and reduce heavy losses caused by fire. Researches on forest fire spread simulation can effectively reduce the loss of disasters. The present study focused on the simulation of "29 May 2012" wildfire in windthrow area of Changbai Mountain. Basic data were retrieved from the "29 May 2012" wildfire and field survey. A self-development forest fire behavior simulated program based on Rothermel Model was used in the simulation. Kappa coefficient and Sørensen index were employed to evaluate the simulation accuracy. The results showed that: The perimeter of simulated burned area was 4.66 km, the area was 56.47 hm2 and the overlapped burned area was 33.68 hm2, and the estimated rate of fire spread was 0.259 m/s. Between the simulated fire and actual fire, the Kappa coefficient was 0.7398 and the Sørensen co-efficient was 0.7419. This proved the application of Rothermel model to conduct fire behavior simulation in windthrow meadow was feasible. It can achieve the goal of forecasting for the spread behavior in windthrow area of Changbai Mountain. Thus, our self-development program based on the Rothermel model can provide a effective forecast of fire spread, which will facilitate the fire suppression work.

Report of the Army Scientific Advisory Panel Ad Hoc Group on Fire Suppression

DTIC Science & Technology

1975-07-01

initially should be provided a nucleus of a seven- person technical staff composed of one 0-6 combat arme officer as Director, two senior behavioral ...If the suppressee perceives the fire as being reactive to his own behavior then the personal danger factor will be reinforced,1 Fire...that is not periodic hut also not reactive to his behavior may be like periodic fire in its personal threat except more difficult to

Ion pair recognition by Zn-porphyrin/crown ether conjugates: visible sensing of sodium cyanide.

PubMed

Kim, Yeon-Hwan; Hong, Jong-In

2002-03-07

Synthesis and complexation behavior of ditopic neutral receptors composed of both a Lewis-acidic binding site (zinc porphyrin moiety) and a Lewis-basic binding site (crown ether moiety) are reported; the receptors bound only NaCN in a ditopic fashion with a color change, and in contrast other sodium salts bound to the receptors in a monotopic fashion without a color change.

Red-cockaded woodpecker foraging behavior

Treesearch

D. Craig Rudolph; Richard N. Conner; Richard R. Schaefer; Nancy E. Koerth

2007-01-01

We studied Red-cockaded Woodpeckers (Picoides borealis) to examine the effect of status and gender on foraging behavior. Foraging behavior of breeding pairs extended beyond separation by foraging height to include zones (bole, trunk in crown, primary limb, secondary limb) of the tree used and foraging methods (scaling, probing, excavating). Helper...

Fire in Mediterranean climate ecosystems: a comparative overview

USGS Publications Warehouse

Keeley, Jon E.

2012-01-01

Four regions of the world share a similar climate and structurally similar plant communities with the Mediterranean Basin. These five areas, known collectively as "mediterranean-type climate (MTC) regions", are dominated by evergreen sclerophyllous-leaved shrublands, semi-deciduous scrub, and woodlands, all of which are prone to widespread crown fires. Summer droughts produce an annual fire hazard that contributes to a highly predictable fire regime. Fire has been an important factor driving the convergence of these systems and is reflected in plant traits such as lignotubers in resprouting shrubs and delayed reproduction that restricts recruitment to a postfire pulse of seedlings. On fertile soils where postfire resprouting is very rapid, opportunities for postfire seedling recruitment are limited and thus these woody taxa have not opted for delaying reproduction. Such fire-independent recruitment is widespread in the floras of MTC regions of the Mediterranean Basin and California and postfire seeding tends to dominate at the more arid end of the gradient. Due to very different geological histories in South Africa and Western Australia, substrates are nutrient poor and thus postfire resprouters do not pose a similar competitive challenge to seedlings and thus postfire seeding is very widespread in these floras. Although circumstantial evidence suggests that the MTC region of Chile had fire-prone landscapes in the Tertiary, these were lost with the late Miocene completion of the Andean uplift, which now blocks summer lightning storms from moving into the region. Today these five regions pose a significant fire management challenge due to the annual fire hazard and metropolitan centers juxtaposed with highly flammable vegetation. This challenge varies across the five MTC landscapes as a function of differences in regional fuel loads and population density.

Fires and Smoke Observed from the Earth Observing System MODIS Instrument: Products, Validation, and Operational Use

NASA Technical Reports Server (NTRS)

Kaufman, Y. J.; Ichoku, C.; Giglio, L.; Korontzi, S.; Chu, D. A.; Hao, W. M.; Justice, C. O.; Lau, William K. M. (Technical Monitor)

2001-01-01

The MODIS sensor, launched on NASA's Terra satellite at the end of 1999, was designed with 36 spectral channels for a wide array of land, ocean, and atmospheric investigations. MODIS has a unique ability to observe fires, smoke, and burn scars globally. Its main fire detection channels saturate at high brightness temperatures: 500 K at 4 microns and 400 K at 11 microns, which can only be attained in rare circumstances at the I kin fire detection spatial resolution. Thus, unlike other polar orbiting satellite sensors with similar thermal and spatial resolutions, but much lower saturation temperatures (e.g. AVHRR and ATSR), MODIS can distinguish between low intensity ground surface fires and high intensity crown forest fires. Smoke column concentration over land is for the first time being derived from the MOMS solar channels, extending from 0.41 microns to 2.1 microns. The smoke product has been provisionally validated both globally and regionally over southern Africa and central and south America. Burn scars are observed from MODIS even in the presence of smoke, using the 1.2 to 2.1 micron channels. MODIS burned area information is used to estimate pyrogenic emissions. A wide range of these fire and related products and validation are demonstrated for the wild fires that occurred in northwestern United States in the summer of 2000. The MODIS rapid response system and direct broadcast capability is being developed to enable users to obtain and generate data in near real time. It is expected that health and land management organizations will use these systems for monitoring the occurrence of fires and the dispersion of smoke within two to six hours after data acquisition.

Firing patterns transition and desynchronization induced by time delay in neural networks

NASA Astrophysics Data System (ADS)

Huang, Shoufang; Zhang, Jiqian; Wang, Maosheng; Hu, Chin-Kun

2018-06-01

We used the Hindmarsh-Rose (HR) model (Hindmarsh and Rose, 1984) to study the effect of time delay on the transition of firing behaviors and desynchronization in neural networks. As time delay is increased, neural networks exhibit diversity of firing behaviors, including regular spiking or bursting and firing patterns transitions (FPTs). Meanwhile, the desynchronization of firing and unstable bursting with decreasing amplitude in neural system, are also increasingly enhanced with the increase of time delay. Furthermore, we also studied the effect of coupling strength and network randomness on these phenomena. Our results imply that time delays can induce transition and desynchronization of firing behaviors in neural networks. These findings provide new insight into the role of time delay in the firing activities of neural networks, and can help to better understand the firing phenomena in complex systems of neural networks. A possible mechanism in brain that can cause the increase of time delay is discussed.

Fire-danger rating and observed wildfire behavior in the Northeastern United States.

Treesearch

Donald A. Haines; William A. Main; Albert J. Simard

1986-01-01

Compares the 1978 National Fire-Danger Rating System and its 20 fuel models, along with other danger rating systems, with observed fire behavior and rates the strengths and weaknesses of models and systems.

Development of a model to predict ash transport and water pollution risk in fire-affected environments

NASA Astrophysics Data System (ADS)

Neris, Jonay; Elliot, William J.; Doerr, Stefan H.; Robichaud, Peter R.

2017-04-01

An estimated that 15% of the world's population lives in volcanic areas. Recent catastrophic erosion events following wildfires in volcanic terrain have highlighted the geomorphological instability of this soil type under disturbed conditions and steep slopes. Predicting the hydrological and erosional response of this soils in the post-fire period is the first step to design and develop adequate actions to minimize risks in the post-fire period. In this work we apply, for the first time, the Water Erosion Prediction Project model for predicting erosion and runoff events in fire-affected volcanic soils in Europe. Two areas affected by wildfires in 2015 were selected in Tenerife (Spain) representative of different fire behaviour (downhill surface fire with long residence time vs uphill crown fire with short residence time), severity (moderate soil burn severity vs light soil burn severity) and climatic conditions (average annual precipitation of 750 and 210 mm respectively). The actual erosion processes were monitored in the field using silt fences. Rainfall and rill simulations were conducted to determine hydrologic, interrill and rill erosion parameters. The soils were sampled and key properties used as model input, evaluated. During the first 18 months after the fire 7 storms produced runoff and erosion in the selected areas. Sediment delivery reached 5.4 and 2.5 Mg ha-1 respectively in the first rainfall event monitored after the fire, figures comparable to those reported for fire-affected areas of the western USA with similar climatic conditions but lower than those showed by wetter environments. The validation of the WEPP model using field data showed reasonable estimates of hillslope sediment delivery in the post-fire period and, therefore, it is suggested that this model can support land managers in volcanic areas in Europe in predicting post-fire hydrological and erosional risks and designing suitable mitigation treatments.

First application of the WEPP model to predict runoff and erosion risk in fire-affected volcanic areas in Europe

NASA Astrophysics Data System (ADS)

Neris, Jonay; Robichaud, Peter R.; Elliot, William J.; Doerr, Stefan H.; Notario del Pino, Jesús S.; Lado, Marcos

2017-04-01

An estimated that 15% of the world's population lives in volcanic areas. Recent catastrophic erosion events following wildfires in volcanic terrain have highlighted the geomorphological instability of this soil type under disturbed conditions and steep slopes. Predicting the hydrological and erosional response of this soils in the post-fire period is the first step to design and develop adequate actions to minimize risks in the post-fire period. In this work we apply, for the first time, the Water Erosion Prediction Project model for predicting erosion and runoff events in fire-affected volcanic soils in Europe. Two areas affected by wildfires in 2015 were selected in Tenerife (Spain) representative of different fire behaviour (downhill surface fire with long residence time vs uphill crown fire with short residence time), severity (moderate soil burn severity vs light soil burn severity) and climatic conditions (average annual precipitation of 750 and 210 mm respectively). The actual erosion processes were monitored in the field using silt fences. Rainfall and rill simulations were conducted to determine hydrologic, interrill and rill erosion parameters. The soils were sampled and key properties used as model input, evaluated. During the first 18 months after the fire 7 storms produced runoff and erosion in the selected areas. Sediment delivery reached 5.4 and 2.5 Mg ha-1 respectively in the first rainfall event monitored after the fire, figures comparable to those reported for fire-affected areas of the western USA with similar climatic conditions but lower than those showed by wetter environments. The validation of the WEPP model using field data showed reasonable estimates of hillslope sediment delivery in the post-fire period and, therefore, it is suggested that this model can support land managers in volcanic areas in Europe in predicting post-fire hydrological and erosional risks and designing suitable mitigation treatments.

Synchronization transition of a coupled system composed of neurons with coexisting behaviors near a Hopf bifurcation

NASA Astrophysics Data System (ADS)

Jia, Bing

2014-05-01

The coexistence of a resting condition and period-1 firing near a subcritical Hopf bifurcation point, lying between the monostable resting condition and period-1 firing, is often observed in neurons of the central nervous systems. Near such a bifurcation point in the Morris—Lecar (ML) model, the attraction domain of the resting condition decreases while that of the coexisting period-1 firing increases as the bifurcation parameter value increases. With the increase of the coupling strength, and parameter and initial value dependent synchronization transition processes from non-synchronization to compete synchronization are simulated in two coupled ML neurons with coexisting behaviors: one neuron chosen as the resting condition and the other the coexisting period-1 firing. The complete synchronization is either a resting condition or period-1 firing dependent on the initial values of period-1 firing when the bifurcation parameter value is small or middle and is period-1 firing when the parameter value is large. As the bifurcation parameter value increases, the probability of the initial values of a period-1 firing neuron that lead to complete synchronization of period-1 firing increases, while that leading to complete synchronization of the resting condition decreases. It shows that the attraction domain of a coexisting behavior is larger, the probability of initial values leading to complete synchronization of this behavior is higher. The bifurcations of the coupled system are investigated and discussed. The results reveal the complex dynamics of synchronization behaviors of the coupled system composed of neurons with the coexisting resting condition and period-1 firing, and are helpful to further identify the dynamics of the spatiotemporal behaviors of the central nervous system.

Influence of the preparation design and artificial aging on the fracture resistance of monolithic zirconia crowns.

PubMed

Mitov, Gergo; Anastassova-Yoshida, Yana; Nothdurft, Frank Phillip; von See, Constantin; Pospiech, Peter

2016-02-01

The aim of this study was to evaluate the fracture resistance and fracture behavior of monolithic zirconia crowns in accordance with the preparation design and aging simulation method. An upper first molar was prepared sequentially with three different preparation designs: shoulderless preparation, 0.4 mm chamfer and 0.8 mm chamfer preparation. For each preparation design, 30 monolithic zirconia crowns were fabricated. After cementation on Cr-Co alloy dies, the following artificial aging procedures were performed: (1) thermal cycling and mechanical loading (TCML): 5000 cycles of thermal cycling 5℃-55℃ and chewing simulation (1,200,000 cycles, 50 N); (2) Low Temperature Degradation simulation (LTD): autoclave treatment at 137℃, 2 bar for 3 hours and chewing simulation; and (3) no pre-treatment (control group). After artificial aging, the crowns were loaded until fracture. The mean values of fracture resistance varied between 3414 N (LTD; 0.8 mm chamfer preparation) and 5712 N (control group; shoulderless preparation). Two-way ANOVA analysis showed a significantly higher fracture loads for the shoulderless preparation, whereas no difference was found between the chamfer preparations. In contrast to TCML, after LTD simulation the fracture strength of monolithic zirconia crowns decreased significantly. The monolithic crowns tested in this study showed generally high fracture load values. Preparation design and LTD simulation had a significant influence on the fracture strength of monolithic zirconia crowns.

Caudate neuronal recording in freely behaving animals following acute and chronic dose response methylphenidate exposure

PubMed Central

Claussen, Catherine M; Dafny, Nachum

2016-01-01

The misuse and abuse of the psychostimulant, methylphenidate (MPD) the drug of choice in the treatment of attention deficit hyperactivity disorder (ADHD) has seen a sharp uprising in recent years among both youth and adults for its cognitive enhancing effects and for recreational purposes. This uprise in illicit use has lead to many questions concerning the long term consequences of MPD exposure. The objective of this study was to record animal behavior concomitantly with the caudate nucleus (CN) neuronal activity following acute and repetitive (chronic) dose response exposure to methylphenidate (MPD). A saline control and three MPD dose (0.6, 2.5, and 10.0 mg/kg) groups were used. Behaviorally, the same MPD dose in some animals following chronic MPD exposure elicited behavioral sensitization and other animals elicited behavioral tolerance. Based on this finding, the CN neuronal population recorded from animals expressing behavioral sensitization were also evaluated separately from CN neurons recorded from animals expressing behavioral tolerance to chronic MPD exposure, respectively. Significant differences in CN neuronal population responses between the behaviorally sensitized and the behaviorally tolerant animals was observed for the 2.5 and 10.0 mg/kg MPD exposed groups. For 2.5 mg/kg MPD, behaviorally sensitized animals responded by decreasing their firing rates while behaviorally tolerant animals showed mainly an increase in their firing rates. The CN neuronal responses recorded from the behaviorally sensitized animals following 10.0 mg/kg MPD responded by increasing their firing rates whereas the CN neuronal recordings from the behaviorally tolerant animals showed that approximately half decreased their firing rates in response to 10.0 mg/kg MPD exposure. The comparison of percentage change in neuronal firing rates showed that the behaviorally tolerant animals trended to exhibit increases in their neuronal firing rates at ED1 following initial MPD exposure and oppositely at ED10 MPD rechallenge. While the behaviorally sensitized animals in general increased in their percentage change of firing rats were observed following acute 10.0 mg/kg MPD and the behaviorally sensitized 10.0 mg/kg MPD animals and a robust increase in neuronal firing rates at ED1 and ED10 rechallenge. These results suggest the need to first individually analyze animal behavioral activity, and than to evaluate the neuronal responses to the drug based on the animals behavioral response to chronic MPD exposure. PMID:26101057

Fire behavior in northern Rocky Mountain forests

Treesearch

J. S. Barrows

1951-01-01

Knowledge of fire behavior is an essential requirement for firefighters. Successful fire control operations depend, first of all, upon the ability of the protection forces to judge where and when fires will start and how they will behave once ignition takes place. Every member of the firefighting team from ranger to smokechaser must be able to make reliable estimates...

BEHAVE: fire behavior prediction and fuel modeling system - BURN subsystem, Part 2

Treesearch

Patricia L. Andrews; Carolyn H. Chase

1989-01-01

This is the third publication describing the BEHAVE system of computer programs for predicting behavior of wildland fires. This publication adds the following predictive capabilities: distance firebrands are lofted ahead of a wind-driven surface fire, probabilities of firebrands igniting spot fires, scorch height of trees, and percentage of tree mortality. The system...

Modeling fuels and fire effects in 3D: Model description and applications

Treesearch

Francois Pimont; Russell Parsons; Eric Rigolot; Francois de Coligny; Jean-Luc Dupuy; Philippe Dreyfus; Rodman R. Linn

2016-01-01

Scientists and managers critically need ways to assess how fuel treatments alter fire behavior, yet few tools currently exist for this purpose.We present a spatially-explicit-fuel-modeling system, FuelManager, which models fuels, vegetation growth, fire behavior (using a physics-based model, FIRETEC), and fire effects. FuelManager's flexible approach facilitates...

Chapter 2: Fire and Fuels Extension: Model description

Treesearch

Sarah J. Beukema; Elizabeth D. Reinhardt; Julee A. Greenough; Donald C. E. Robinson; Werner A. Kurz

2003-01-01

The Fire and Fuels Extension to the Forest Vegetation Simulator is a model that simulates fuel dynamics and potential fire behavior over time, in the context of stand development and management. Existing models are used to represent forest stand development (the Forest Vegetation Simulator, Wykoff and others 1982), fire behavior (Rothermel 1972, Van Wagner 1977, and...

Research efforts on fuels, fuel models, and fire behavior in eastern hardwood forests

Treesearch

Thomas A. Waldrop; Lucy Brudnak; Ross J. Phillips; Patrick H. Brose

2006-01-01

Although fire was historically important to most eastern hardwood systems, its reintroduction by prescribed burning programs has been slow. As a result, less information is available on these systems to fire managers. Recent research and nationwide programs are beginning to produce usable products to predict fuel accumulation and fire behavior. We introduce some of...

Fire fighting aboard ships. Volume 1: Hazard analysis and behavior of combustible materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stavitskiy, M.G.; Kortunov, M.F.; Sidoryuk, V.M.

1983-01-01

The volume zeros in on fire hazards on ships afloat or under construction/repair. It examines fire hazards peculiar to ships carrying particular cargoes, such as dry-cargo ships, tankers, and factory and fishing vessels. This volume examines specific features of fire-fighting equipment, along with the thermal behavior of materials used in shipbuilding.

Potential fire behavior in pine flatwood forests following three different fuel reduction techniques

Treesearch

Patrick Brose; Dale Wade

2002-01-01

A computer modeling study to determine the potential fire behavior in pine flatwood forests following three fuel hazard reduction treatments: herbicide, prescribed fire and thinning was conducted in Florida following the 1998 wildfire season. Prescribed fire provided immediate protection but this protection quickly disappeared as the rough recovered. Thinning had a...

Measuring fire behavior with photography

Treesearch

Hubert B. Clements; Darold E. Ward; Carl W. Adkins

1983-01-01

Photography is practical for recording and measuring some aspects of forest fire behavior if the scale and perspective can be determined. This paper describes a photogrammetric method for measuring flame height and rate of spread for fires on flat terrain. The flames are photographed at known times with a camera in front of the advancing fire. Scale and perspective of...

Failure probability of three designs of zirconia crowns

PubMed Central

Ramos, G. Freitas; Monteiro, E. Barbosa Carmona; Bottino, M.A.; Zhang, Y.; de Melo, R. Marques

2015-01-01

Objectives This study utilized a 2-parameter Weibull analysis for evaluation of lifetime of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. Methods Sixty first molars were selected and prepared for full-coverage crowns with three different designs(n = 20): Traditional –crowns with zirconia framework covered with feldspathic porcelain; Modified– crowns partially covered with veneering porcelain; and Monolithic–full-contour zirconia crowns. All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100N, 3Hz) with a piston with hemispherical tip (Ø=6 mm) until the specimens failed or up to 2×106 cycles. Every 500,000 cycles intervals, the fatigue tests were interrupted, and stereomicroscopy (10 X) was used to inspect the specimens for damage. We performed Weibull analysis of interval data to calculate the number of failures in each interval. Results The types and number of failures according to the groups were: cracking (Traditional-13, Modified-6) and chipping (Traditional-4) of the feldspathic porcelain, followed by delamination (Traditional-1) at the veneer/core interface and debonding (Monollithic-2) at the cementation interface. Weibull parameters (beta, scale; and eta, shape), with a two-sided confidence interval of 95%, were: Traditional – 1.25 and 0.9 × 106cycles; Modified– 0.58 and 11.7 × 106 cycles; and Monolithic – 1.05 and 16.5 × 106 cycles. Traditional crowns showed greater susceptibility to fatigue, the Modified group presented higher propensity to early failures, and the Monolithic group showed no susceptibility to fatigue. The Modified and Monolithic groups presented the highest number of crowns with no failures after the fatigue test. Conclusions The three crown designs presented significantly different behaviors under fatigue. The Modified and the Monolithic groups presented less probability to failure after 2×106cycles. PMID:26509988

Spatially explicit measurements of forest structure and fire behavior following restoration treatments in dry forests

Treesearch

Justin Paul Ziegler; Chad Hoffman; Michael Battaglia; William Mell

2017-01-01

Restoration treatments in dry forests of the western US often attempt silvicultural practices to restore the historical characteristics of forest structure and fire behavior. However, it is suggested that a reliance on non-spatial metrics of forest stand structure, along with the use of wildland fire behavior models that lack the ability to handle complex structures,...

Modeling fire behavior on tropical islands with high-resolution weather data

Treesearch

John W. Benoit; Francis M. Fujioka; David R. Weise

2009-01-01

In this study, we consider fire behavior simulation in tropical island scenarios such as Hawaii and Puerto Rico. The development of a system to provide real-time fire behavior prediction in Hawaii is discussed. This involves obtaining fuels and topography information at a fine scale, as well as supplying daily high-resolution weather forecast data for the area of...

Resistance is not futile: The response of hardwoods to fire-caused wounding

Treesearch

Elaine Kennedy Sutherland; Kevin Smith

2000-01-01

Fires wound trees; but not all of them, and not always. Specific fire behavior and differences among tree species and individual trees produce variable patterns of wounding and wound response. Our work focuses on the relationships between fire behavior and tree biology to better understand how hardwood trees resist injury to the lower stem and either survive or succumb...

Exposure to fire setting behavior on YouTube.

PubMed

Thomas, Meara; Mackay, Sherri; Salsbury, Debbie

2012-07-01

This study is a preliminary examination of fire setting behaviors on YouTube. Data are based on a 1 day search of YouTube. Results indicate YouTube is replete with inappropriate models of fire setting. The findings have potential implications for intervention with fire setting youth. Copyright © 2012 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Building Fire Behavior Analyst (FBAN) capability and capacity: Lessons learned From Victoria, Australia's Bushfire Behavior Predictive Services Strategy

Treesearch

K. E. Gibos; A. Slijepcevic; T. Wells; L. Fogarty

2015-01-01

Wildland fire managers must frequently make meaning from chaos in order to protect communities and infrastructure from the negative impacts of fire. Fire management personnel are increasingly turning to science to support their experience-based decision-making processes and to provide clear, confident leadership for communities frequently exposed to risk from wildfire...

Mastication and prescribed fire influences on tree mortality and predicted fire behavior in ponderosa pine

Treesearch

Alicia L. Reiner; Nicole M. Vaillant; Scott N. Dailey

2012-01-01

The purpose of this study was to provide land managers with information on potential wildfire behavior and tree mortality associated with mastication and masticated/fire treatments in a plantation. Additionally, the effect of pulling fuels away from tree boles before applying fire treatment was studied in relation to tree mortality. Fuel characteristics and tree...

Utilization of remote sensing techniques for the quantification of fire behavior in two pine stands

Treesearch

Eric V. Mueller; Nicholas Skowronski; Kenneth Clark; Michael Gallagher; Robert Kremens; Jan C. Thomas; Mohamad El Houssami; Alexander Filkov; Rory M. Hadden; William Mell; Albert Simeoni

2017-01-01

Quantification of field-scale fire behavior is necessary to improve the current scientific understanding of wildland fires and to develop and test relevant, physics-based models. In particular, detailed descriptions of individual fires are required, for which the available literature is limited. In this work, two such field-scale experiments, carried out in pine stands...

A tale of two fires: The relative effectiveness of past wildfires in mitigating wildfire behavior and effects

Treesearch

Robert W. Gray; Susan J. Prichard

2015-01-01

The incidence of large, costly landscape-scale fires in western North America is increasing. To combat these fires, researchers and managers have expressed increased interest in investigating the effectiveness of past, stand-replacing wildfires as bottom-up controls on fire spread and severity. Specifically, how effective are past wildfires in mitigating the behavior...

Prioritizing forest fuels treatments based on the probability of high-severity fire restores adaptive capacity in Sierran forests.

PubMed

Krofcheck, Daniel J; Hurteau, Matthew D; Scheller, Robert M; Loudermilk, E Louise

2018-02-01

In frequent fire forests of the western United States, a legacy of fire suppression coupled with increases in fire weather severity have altered fire regimes and vegetation dynamics. When coupled with projected climate change, these conditions have the potential to lead to vegetation type change and altered carbon (C) dynamics. In the Sierra Nevada, fuels reduction approaches that include mechanical thinning followed by regular prescribed fire are one approach to restore the ability of the ecosystem to tolerate episodic fire and still sequester C. Yet, the spatial extent of the area requiring treatment makes widespread treatment implementation unlikely. We sought to determine if a priori knowledge of where uncharacteristic wildfire is most probable could be used to optimize the placement of fuels treatments in a Sierra Nevada watershed. We developed two treatment placement strategies: the naive strategy, based on treating all operationally available area and the optimized strategy, which only treated areas where crown-killing fires were most probable. We ran forecast simulations using projected climate data through 2,100 to determine how the treatments differed in terms of C sequestration, fire severity, and C emissions relative to a no-management scenario. We found that in both the short (20 years) and long (100 years) term, both management scenarios increased C stability, reduced burn severity, and consequently emitted less C as a result of wildfires than no-management. Across all metrics, both scenarios performed the same, but the optimized treatment required significantly less C removal (naive=0.42 Tg C, optimized=0.25 Tg C) to achieve the same treatment efficacy. Given the extent of western forests in need of fire restoration, efficiently allocating treatments is a critical task if we are going to restore adaptive capacity in frequent-fire forests. © 2017 John Wiley & Sons Ltd.

Postfire Forest Recovery in California's National Forests

NASA Astrophysics Data System (ADS)

Welch, K.; Young, T.; Safford, H.

2012-12-01

Due to fire suppression policies and other management practices over the last century, many low- to mid-elevation forest types in the Sierra Nevada have accumulated high fuel loads that promote stand-replacing high-intensity fires. Current and future projected trends in climate are predicted to increase the occurrence of such fires. We established over 1,000 plots in a range of elevations, environments, forest types, climate zones and fire severity classes to provide insight into the factors that promote natural tree regeneration after wildfires, the limiting factors in species establishment, and the differences in post-fire responses of conifers and hardwoods. We employed a standardized protocol that measured site characteristics, seedling densities, and woody plant growth. Preliminary results reveal that fire severity generally has a unimodal relationship with rates of natural regeneration, although effects of site and local environment act to modulate the shape of the relationship. Above low to moderate severities, natural regeneration rates of all tree species decrease with increasing severity, possibly due to a combination of factors including seed mortality, increasing distance to the nearest living seed tree, and more severe microclimatic conditions. Though hardwoods (oaks) are able to both seed and resprout from top-killed root crowns in a postfire environment, conifers still have the numerical advantage over hardwoods through seeding alone. We did not find evidence that shrubs have a strong either facilitative or competitive effect on conifer seedling establishment or growth in the first five years of forest recovery. Understanding forest recovery and regeneration processes after high severity fires is critical to appropriately applying management strategies on National Forest lands.

Using behavioral science to improve fire escape behaviors in response to a smoke alarm.

PubMed

Thompson, N J; Waterman, M B; Sleet, D A

2004-01-01

Although the likelihood of fire-related death in homes with smoke alarms is about one-half that in homes without alarms, alarm effectiveness is limited by behavior. Only 16% of residents of homes with alarms have developed and practiced plans for escape when the alarm sounds. We reviewed literature to identify behavioral constructs that influence smoke alarm use. We then convened experts in the behavioral aspects of smoke alarms who reviewed the constructs and determined that the appropriate areas for behavioral focus were formulating, practicing, and implementing escape plans should an alarm sound. They subsequently identified important behaviors to be addressed by burn-prevention programs and incorporated the constructs into a behavioral model for use in such programs. Finally, we organized the available literature to support this model and make programmatic recommendations. Many gaps remain in behavioral research to improve fire escape planning and practice. Future research must select the target behavior, apply behavioral theories, and distinguish between initiation and maintenance of behaviors associated with planning, practicing, and implementing home fire escape plans.

Fire history and fire-climate relationships in upper elevation forests of the southwestern United States

NASA Astrophysics Data System (ADS)

Margolis, Ellis Quinn

Fire history and fire-climate relationships of upper elevation forests of the southwestern United States are imperative for informing management decisions in the face of increased crown fire occurrence and climate change. I used dendroecological techniques to reconstruct fires and stand-replacing fire patch size in the Madrean Sky Islands and Mogollon Plateau. Reconstructed patch size (1685-1904) was compared with contemporary patch size (1996-2004). Reconstructed fires at three sites had stand-replacing patches totaling > 500 ha. No historical stand-replacing fire patches were evident in the mixed conifer/aspen forests of the Sky Islands. Maximum stand-replacing fire patch size of modern fires (1129 ha) was greater than that reconstructed from aspen (286 ha) and spruce-fir (521 ha). Undated spruce-fir patches may be evidence of larger (>2000ha) stand-replacing fire patches. To provide climatological context for fire history I used correlation and regionalization analyses to document spatial and temporal variability in climate regions, and El-Nino Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO) teleconnections using 273 tree-ring chronologies (1732-1979). Four regions were determined by common variability in annual ring width. The component score time series replicate spatial variability in 20th century droughts (e.g., 1950's) and pluvials (e.g., 1910's). Two regions were significantly correlated with instrumental SOI and AMO, and three with PDO. Sub-regions within the southwestern U.S. varied geographically between the instrumental (1900-1979) and the pre-instrumental periods (1732-1899). Mapped correlations between ENSO, PDO and AMO, and tree-ring indices illustrate detailed sub-regional variability in the teleconnections. I analyzed climate teleconnections, and fire-climate relationships of historical upper elevation fires from 16 sites in 8 mountain ranges. I tested for links between Palmer Drought Severity Index and tree-ring reconstructed ENSO, PDO and AMO phases (1905-1978 and 1700-1904). Upper elevation fires (115 fires, 84 fire years, 1623-1904) were compared with climate indices. ENSO, PDO, and AMO affected regional PDSI, but AMO and PDO teleconnections changed between periods. Fire occurrence was significantly related to inter-annual variability in PDSI, precipitation, ENSO, and phase combinations of ENSO and PDO, but not AMO (1700-1904). Reduced upper elevation fire (1785-1840) was coincident with a cool AMO phase.

Fractography of clinically fractured, implant-supported dental computer-aided design and computer-aided manufacturing crowns

PubMed Central

Lohbauer, Ulrich; Belli, Renan; Cune, Marco S; Schepke, Ulf

2017-01-01

Today, a substantial part of the dental crown production uses computer-aided design and computer-aided manufacturing (CAD/CAM) technology. A recent step in restorative dentistry is the replacement of natural tooth structure with pre-polymerized and machined resin-based methacrylic polymers. Recently, a new CAD/CAM composite was launched for the crown indication in the load-bearing area, but the clinical reality forced the manufacturer to withdraw this specific indication. In parallel, a randomized clinical trial of CAD/CAM composite crowns luted on zirconia implant abutments revealed a high incidence of failure within the first year of service. Fractured crowns of this clinical trial were retrieved and submitted to a fractographic examination. The aim of the case series presented in this article was to identify failure reasons for a new type of CAD/CAM composite crown material (Lava Ultimate; 3M Oral Care, St. Paul, Minnesota, USA) via fractographic examinations and analytical assessment of luting surfaces and water absorption behavior. As a result, the debonding of the composite crowns from the zirconia implant abutments was identified as the central reason for failure. The adhesive interface was found the weakest link. A lack of silica at the zirconia surface certainly has compromised the bonding potential of the adhesive system from the beginning. Additionally, the hydrolytic stress released from swelling of the resin-based crown (water absorption) and transfer to the luting interface further added to the interfacial stress and most probably contributed to a great extend to the debonding failure. PMID:29204275

Fractography of clinically fractured, implant-supported dental computer-aided design and computer-aided manufacturing crowns.

PubMed

Lohbauer, Ulrich; Belli, Renan; Cune, Marco S; Schepke, Ulf

2017-01-01

Today, a substantial part of the dental crown production uses computer-aided design and computer-aided manufacturing (CAD/CAM) technology. A recent step in restorative dentistry is the replacement of natural tooth structure with pre-polymerized and machined resin-based methacrylic polymers. Recently, a new CAD/CAM composite was launched for the crown indication in the load-bearing area, but the clinical reality forced the manufacturer to withdraw this specific indication. In parallel, a randomized clinical trial of CAD/CAM composite crowns luted on zirconia implant abutments revealed a high incidence of failure within the first year of service. Fractured crowns of this clinical trial were retrieved and submitted to a fractographic examination. The aim of the case series presented in this article was to identify failure reasons for a new type of CAD/CAM composite crown material (Lava Ultimate; 3M Oral Care, St. Paul, Minnesota, USA) via fractographic examinations and analytical assessment of luting surfaces and water absorption behavior. As a result, the debonding of the composite crowns from the zirconia implant abutments was identified as the central reason for failure. The adhesive interface was found the weakest link. A lack of silica at the zirconia surface certainly has compromised the bonding potential of the adhesive system from the beginning. Additionally, the hydrolytic stress released from swelling of the resin-based crown (water absorption) and transfer to the luting interface further added to the interfacial stress and most probably contributed to a great extend to the debonding failure.

A system to evaluate fire impacts from simulated fire behavior in Mediterranean areas of Central Chile.

PubMed

Castillo, Miguel E; Molina, Juan R; Rodríguez Y Silva, Francisco; García-Chevesich, Pablo; Garfias, Roberto

2017-02-01

Wildfires constitute the greatest economic disruption to Mediterranean ecosystems, from a socio-economic and ecological perspective (Molina et al., 2014). This study proposes to classify fire intensity levels based on potential fire behavior in different types of Mediterranean vegetation types, using two geographical scales. The study considered >4 thousand wildfires over a period of 25years, identifying fire behavior on each event, based on simulations using "KITRAL", a model developed in Chile in 1993 and currently used in the entire country. Fire intensity values allowed results to be classified into six fire effects categories (levels), each of them with field indicators linking energy values with damage related to burned vegetation and wildland urban interface zone. These indicators also facilitated a preliminary assessment of wildfire impact on different Mediterranean land uses and, are therefore, a useful tool to prioritize future interventions. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydrologic Vulnerability and Risk Assessment Associated With the Increased Role of Fire on Western Landscapes, Great Basin, USA

NASA Astrophysics Data System (ADS)

Williams, C. J.; Pierson, F. B.; Robichaud, P. R.; Spaeth, K. E.; Hardegree, S. P.; Clark, P. E.; Moffet, C. A.; Al-Hamdan, O. Z.; Boll, J.

2010-12-01

Landscape-scale plant community transitions and altered fire regimes across Great Basin, USA, rangelands have increased the likelihood of post-fire flooding and erosion events. These hazards are particularly concerning for western urban centers along the rangeland urban-wildland interface where natural resources, property, and human life are at risk. Extensive conversion of 4-7 million hectares of Great Basin shrub-steppe to cheatgrass-dominated (Bromus tectorum) grasslands has increased the frequency and size of wildland fires within these ecosystems. Fire frequencies have increased by more than an order of magnitude and occur on 3-10 year intervals across much of the cheatgrass-dominated landscape. Extensive tree (Pinus spp. and Juniperus spp.) encroachment into wooded shrub-steppe has increased heavy fuel loads. Ladder fuels in these ecosystems promote rapidly spreading, high-intensity and severe ground-surface-crown fires. These altered fuel structures across much of the historical Great Basin shrub-steppe have initiated an upsurge in large rangeland wildfires and have increased the spatial and temporal vulnerability of these landscapes to amplified runoff and erosion. Resource and infrastructure damages, and loss of life have been reported due to flooding following recent large-scale burning of western rangelands and dry forests. We present a decade of post-fire rangeland hydrologic research that provides a foundation for conceptual modeling of the hydrologic impacts associated with an increased role of rangeland wildfires. We highlight advancements in predictive tools to address this large-scale phenomenon and discuss vital research voids requiring attention. Our geographic emphasis is the Great Basin Region, however, these concepts likely extend elsewhere given the increased role of fire in many geographic regions and across rangeland-to-forest ecotones in the western United States.

Winds, Mountains, and Wildland Fire: Improved Understanding of Coupled Atmosphere-Topography-Fire Interactions Through Large-Eddy Simulation

NASA Astrophysics Data System (ADS)

Munoz-Esparza, D.; Sauer, J.; Linn, R.

2015-12-01

Anomalous and unexpected fire behavior in complex terrain continues to result in substantial loss of property and extremely dangerous conditions for firefighting field personnel. We briefly discuss proposed hypotheses of fire interactions with atmospheric flows over complex terrain that can lead to poorly-understood and potentially catastrophic scenarios. Then, our recent results of numerical investigations via large-eddy simulation of coupled atmosphere-topography-fire phenomenology with the Los Alamos National Laboratory, HiGrad-Firetec model are presented as an example of the potential for increased understanding of these complex processes. This investigation focuses on the influence of downslope surface wind enhancement through stably stratified flow over an isolated hill, and the resulting dramatic changes in fire behavior including spread rate, and intensity. Implications with respect to counter-intuitive fire behavior and extreme fire events are discussed. This work demonstrates a tremendous opportunity to immediately create safer and more effective policy for field personnel through improved predictability of atmospheric conditions over complex terrain

Fuel loads and simulated fire behavior in "old-stage" beetle-infested ponderosa pine of the Colorado Plateau

Treesearch

E. Matthew Hansen; Morris C. Johnson; Barbara J. Bentz; James C. Vandygriff; A. Steven Munson

2015-01-01

Recent bark beetle outbreaks in western North America have led to concerns regarding changes in fuel profiles and associated changes in fire behavior. Data are lacking for a range of infestation severities and time since outbreak, especially for relatively arid cover types. We surveyed fuel loads and simulated fire behavior for ponderosa pine stands of the...

Interactions of landscape disturbances and climate change dictate ecological pattern and process: spatial modeling of wildfire, insect, and disease dynamics under future climates

USGS Publications Warehouse

Loehman, Rachel A.; Keane, Robert E.; Holsinger, Lisa M.; Wu, Zhiwei

2016-01-01

ContextInteractions among disturbances, climate, and vegetation influence landscape patterns and ecosystem processes. Climate changes, exotic invasions, beetle outbreaks, altered fire regimes, and human activities may interact to produce landscapes that appear and function beyond historical analogs.ObjectivesWe used the mechanistic ecosystem-fire process model FireBGCv2 to model interactions of wildland fire, mountain pine beetle (Dendroctonus ponderosae), and white pine blister rust (Cronartium ribicola) under current and future climates, across three diverse study areas.MethodsWe assessed changes in tree basal area as a measure of landscape response over a 300-year simulation period for the Crown of the Continent in north-central Montana, East Fork of the Bitterroot River in western Montana, and Yellowstone Central Plateau in western Wyoming, USA.ResultsInteracting disturbances reduced overall basal area via increased tree mortality of host species. Wildfire decreased basal area more than beetles or rust, and disturbance interactions modeled under future climate significantly altered landscape basal area as compared with no-disturbance and current climate scenarios. Responses varied among landscapes depending on species composition, sensitivity to fire, and pathogen and beetle suitability and susceptibility.ConclusionsUnderstanding disturbance interactions is critical for managing landscapes because forest responses to wildfires, pathogens, and beetle attacks may offset or exacerbate climate influences, with consequences for wildlife, carbon, and biodiversity.

Probability model for analyzing fire management alternatives: theory and structure

Treesearch

Frederick W. Bratten

1982-01-01

A theoretical probability model has been developed for analyzing program alternatives in fire management. It includes submodels or modules for predicting probabilities of fire behavior, fire occurrence, fire suppression, effects of fire on land resources, and financial effects of fire. Generalized "fire management situations" are used to represent actual fire...

Forest-fire models

Treesearch

Haiganoush Preisler; Alan Ager

2013-01-01

For applied mathematicians forest fire models refer mainly to a non-linear dynamic system often used to simulate spread of fire. For forest managers forest fire models may pertain to any of the three phases of fire management: prefire planning (fire risk models), fire suppression (fire behavior models), and postfire evaluation (fire effects and economic models). In...

Integrating fire behavior models and geospatial analysis for wildland fire risk assessment and fuel management planning

Treesearch

Alan A. Ager; Nicole M. Vaillant; Mark A. Finney

2011-01-01

Wildland fire risk assessment and fuel management planning on federal lands in the US are complex problems that require state-of-the-art fire behavior modeling and intensive geospatial analyses. Fuel management is a particularly complicated process where the benefits and potential impacts of fuel treatments must be demonstrated in the context of land management goals...

Fuels and predicted fire behavior in the southern Appalachian Mountains and fire and fire surrogate treatments

Treesearch

Thomas Waldrop; Ross J. Phillips; Dean A. Simon

2010-01-01

This study tested the success of fuel reduction treatments for mitigating wildfire behavior in an area that has had little previous research on fire, the southern Appalachian Mountains. A secondary objective of treatments was to restore the community to an open woodland condition. Three blocks of four treatments were installed in a mature hardwood forest in western...

Fuel and fire behavior in high-elevation five-needle pines affected by mountain pine beetle

Treesearch

Michael J. Jenkins

2011-01-01

Bark beetle-caused tree mortality in conifer forests affects the quantity and quality of forest fuels and has long been assumed to increase fire hazard and potential fire behavior. In reality, bark beetles and their effects on fuel accumulation and subsequent fire hazard have only recently been described. We have extensively sampled fuels in three conifer forest types...

Numerical Field Model Simulation of Full Scale Fire Tests in a Closed Spherical/Cylindrical Vessel.

DTIC Science & Technology

1987-12-01

the behavior of an actual fire on board a ship. The computer model will be verified by the experimental data obtained in Fire-l. It is important to... behavior in simulations where convection is important. The upwind differencing scheme takes into account the unsymmetrical phenomenon of convection by using...TANK CELL ON THE NORTH SIDE) FOR A * * PARTICULAR FIRE CELL * * COSUMS (I,J) = THE ARRAY TO STORE THE SIMILIAR VALUE FOR THE FIRE * * CELL TO THE SOUTH

The compensatory interaction between motor unit firing behavior and muscle force during fatigue

PubMed Central

De Luca, Carlo J.; Kline, Joshua C.

2016-01-01

Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. PMID:27385798

The compensatory interaction between motor unit firing behavior and muscle force during fatigue.

PubMed

Contessa, Paola; De Luca, Carlo J; Kline, Joshua C

2016-10-01

Throughout the literature, different observations of motor unit firing behavior during muscle fatigue have been reported and explained with varieties of conjectures. The disagreement amongst previous studies has resulted, in part, from the limited number of available motor units and from the misleading practice of grouping motor unit data across different subjects, contractions, and force levels. To establish a more clear understanding of motor unit control during fatigue, we investigated the firing behavior of motor units from the vastus lateralis muscle of individual subjects during a fatigue protocol of repeated voluntary constant force isometric contractions. Surface electromyographic decomposition technology provided the firings of 1,890 motor unit firing trains. These data revealed that to sustain the contraction force as the muscle fatigued, the following occurred: 1) motor unit firing rates increased; 2) new motor units were recruited; and 3) motor unit recruitment thresholds decreased. Although the degree of these adaptations was subject specific, the behavior was consistent in all subjects. When we compared our empirical observations with those obtained from simulation, we found that the fatigue-induced changes in motor unit firing behavior can be explained by increasing excitation to the motoneuron pool that compensates for the fatigue-induced decrease in muscle force twitch reported in empirical studies. Yet, the fundamental motor unit control scheme remains invariant throughout the development of fatigue. These findings indicate that the central nervous system regulates motor unit firing behavior by adjusting the operating point of the excitation to the motoneuron pool to sustain the contraction force as the muscle fatigues. Copyright © 2016 the American Physiological Society.

Influence of the preparation design and artificial aging on the fracture resistance of monolithic zirconia crowns

PubMed Central

Anastassova-Yoshida, Yana; Nothdurft, Frank Phillip; von See, Constantin; Pospiech, Peter

2016-01-01

PURPOSE The aim of this study was to evaluate the fracture resistance and fracture behavior of monolithic zirconia crowns in accordance with the preparation design and aging simulation method. MATERIALS AND METHODS An upper first molar was prepared sequentially with three different preparation designs: shoulderless preparation, 0.4 mm chamfer and 0.8 mm chamfer preparation. For each preparation design, 30 monolithic zirconia crowns were fabricated. After cementation on Cr-Co alloy dies, the following artificial aging procedures were performed: (1) thermal cycling and mechanical loading (TCML): 5000 cycles of thermal cycling 5℃–55℃ and chewing simulation (1,200,000 cycles, 50 N); (2) Low Temperature Degradation simulation (LTD): autoclave treatment at 137℃, 2 bar for 3 hours and chewing simulation; and (3) no pre-treatment (control group). After artificial aging, the crowns were loaded until fracture. RESULTS The mean values of fracture resistance varied between 3414 N (LTD; 0.8 mm chamfer preparation) and 5712 N (control group; shoulderless preparation). Two-way ANOVA analysis showed a significantly higher fracture loads for the shoulderless preparation, whereas no difference was found between the chamfer preparations. In contrast to TCML, after LTD simulation the fracture strength of monolithic zirconia crowns decreased significantly. CONCLUSION The monolithic crowns tested in this study showed generally high fracture load values. Preparation design and LTD simulation had a significant influence on the fracture strength of monolithic zirconia crowns. PMID:26949485

Developing custom fire behavior fuel models from ecologically complex fuel structures for upper Atlantic Coastal Plain forests.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parresol, Bernard, R.; Scott, Joe, H.; Andreu, Anne

2012-01-01

Currently geospatial fire behavior analyses are performed with an array of fire behavior modeling systems such as FARSITE, FlamMap, and the Large Fire Simulation System. These systems currently require standard or customized surface fire behavior fuel models as inputs that are often assigned through remote sensing information. The ability to handle hundreds or thousands of measured surface fuelbeds representing the fine scale variation in fire behavior on the landscape is constrained in terms of creating compatible custom fire behavior fuel models. In this study, we demonstrate an objective method for taking ecologically complex fuelbeds from inventory observations and converting thosemore » into a set of custom fuel models that can be mapped to the original landscape. We use an original set of 629 fuel inventory plots measured on an 80,000 ha contiguous landscape in the upper Atlantic Coastal Plain of the southeastern United States. From models linking stand conditions to component fuel loads, we impute fuelbeds for over 6000 stands. These imputed fuelbeds were then converted to fire behavior parameters under extreme fuel moisture and wind conditions (97th percentile) using the fuel characteristic classification system (FCCS) to estimate surface fire rate of spread, surface fire flame length, shrub layer reaction intensity (heat load), non-woody layer reaction intensity, woody layer reaction intensity, and litter-lichen-moss layer reaction intensity. We performed hierarchical cluster analysis of the stands based on the values of the fire behavior parameters. The resulting 7 clusters were the basis for the development of 7 custom fire behavior fuel models from the cluster centroids that were calibrated against the FCCS point data for wind and fuel moisture. The latter process resulted in calibration against flame length as it was difficult to obtain a simultaneous calibration against both rate of spread and flame length. The clusters based on FCCS fire behavior parameters represent reasonably identifiable stand conditions, being: (1) pine dominated stands with more litter and down woody debriscomponents than other stands, (2) hardwood and pine stands with no shrubs, (3) hardwood dominated stands with low shrub and high non-woody biomass and high down woody debris, (4) stands with high grass and forb (i.e., non-woody) biomass as well as substantial shrub biomass, (5) stands with both high shrub and litter biomass, (6) pine-mixed hardwood stands with moderate litter biomass and low shrub biomass, and (7) baldcypress-tupelo stands. Models representing these stand clusters generated flame lengths from 0.6 to 2.3 musing a 30 km h{sub 1} wind speed and fireline intensities of 100-1500 kW m{sub 1} that are typical within the range of experience on this landscape. The fuel models ranked 1 < 2 < 7 < 5 < 4 < 3 < 6 in terms of both flame length and fireline intensity. The method allows for ecologically complex data to be utilized in order to create a landscape representative of measured fuel conditions and to create models that interface with geospatial fire models.« less

Chapter 13 - Conventional fire behavior modeling systems are inadequate for predicting fire behavior in bark beetle-impacted forests (Project INT-EM-F-11-03)

Treesearch

Sharon M. Hood; Robert E. Keane; Helen Y. Smith; Joel Egan; Lisa Holsinger

2018-01-01

Understanding the impacts of mountain pine beetle (MPB; Dendroctonus ponderosae Hopkins) on fire behavior is important from both an ecological and land management viewpoint. However, numerous uncertainties exist in the linkages of MPB-caused treemortality to changes in canopy and surface fuels (e.g., fuel loading, arrangement, and availability) and the...

Burning Down the Silos: Integrating new perspectives from the social sciences into human behavior in fire research.

PubMed

Kuligowski, Erica

2017-01-01

The traditional social science disciplines can provide many benefits to the field of human behavior in fire (HBiF). First, the social sciences delve further into insights only marginally examined by HBiF researchers, in turn, expanding the depth of HBiF research. In this paper, I present examples of studies from the fields of social psychology and sociology that would expand HBiF research into non-engineering or "unobservable" aspects of behavior during a fire event. Second, the social sciences can provide insight into new areas of research; in turn, expanding the scope of HBiF research. In this section, I introduce pre- and post-fire studies and explore potential research questions that fall outside of the response period of a fire, the phase upon which most focus is currently placed. Third, the social sciences elucidate the value of research methods available to study human behavior. Qualitative research methods are specifically highlighted. These three benefits will allow HBiF researchers to collect a wider range of data, further develop and expand current behavioral knowledge, and increase the impact of this research for both social and engineering applications. Finally, I end with a discussion on possible ways to better integrate the social sciences within human behavior in fire.

Differential Activation of Fast-Spiking and Regular-Firing Neuron Populations During Movement and Reward in the Dorsal Medial Frontal Cortex

PubMed Central

Insel, Nathan; Barnes, Carol A.

2015-01-01

The medial prefrontal cortex is thought to be important for guiding behavior according to an animal's expectations. Efforts to decode the region have focused not only on the question of what information it computes, but also how distinct circuit components become engaged during behavior. We find that the activity of regular-firing, putative projection neurons contains rich information about behavioral context and firing fields cluster around reward sites, while activity among putative inhibitory and fast-spiking neurons is most associated with movement and accompanying sensory stimulation. These dissociations were observed even between adjacent neurons with apparently reciprocal, inhibitory–excitatory connections. A smaller population of projection neurons with burst-firing patterns did not show clustered firing fields around rewards; these neurons, although heterogeneous, were generally less selective for behavioral context than regular-firing cells. The data suggest a network that tracks an animal's behavioral situation while, at the same time, regulating excitation levels to emphasize high valued positions. In this scenario, the function of fast-spiking inhibitory neurons is to constrain network output relative to incoming sensory flow. This scheme could serve as a bridge between abstract sensorimotor information and single-dimensional codes for value, providing a neural framework to generate expectations from behavioral state. PMID:24700585

Cork Oak Vulnerability to Fire: The Role of Bark Harvesting, Tree Characteristics and Abiotic Factors

PubMed Central

Catry, Filipe X.; Moreira, Francisco; Pausas, Juli G.; Fernandes, Paulo M.; Rego, Francisco; Cardillo, Enrique; Curt, Thomas

2012-01-01

Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees) that occurred in three southern European countries (Portugal, Spain and France), covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting) were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals) and decreased with increasing bark thickness until cork was 3–4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle) would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems. PMID:22787521

Firefighter attitudes, norms, beliefs, barriers, and behaviors toward post-fire decontamination processes in an era of increased cancer risk.

PubMed

Harrison, Tyler R; Muhamad, Jessica Wendorf; Yang, Fan; Morgan, Susan E; Talavera, Ed; Caban-Martinez, Alberto; Kobetz, Erin

2018-04-01

Firefighters are exposed to carcinogens such as volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) during fires and from their personal protective equipment (PPE). Recent research has shown that decontamination processes can reduce contamination on both gear and skin. While firefighter cultures that honor dirty gear are changing, little is known about current attitudes and behaviors toward decontamination in the fire service. Four hundred eighty-five firefighters from four departments completed surveys about their attitudes, beliefs, perceived norms, barriers, and behaviors toward post-fire decontamination processes. Overall, firefighters reported positive attitudes, beliefs, and perceived norms about decontamination, but showering after a fire was the only decontamination process that occurred regularly, with field decontamination, use of cleansing wipes, routine gear cleaning, and other behaviors all occurring less frequently. Firefighters reported time and concerns over wet gear as barriers to decontamination.

Convection and downbursts

Treesearch

Joseph J. Charney; Brian E. Potter

2017-01-01

Convection and downbursts are connected meteorological phenomena with the potential to affect fire behavior and thereby alter the evolution of a wildland fire. Meteorological phenomena related to convection and downbursts are often discussed in the context of fire behavior and smoke. The physical mechanisms that contribute to these phenomena are interrelated, but the...

Influence of surface finishing on fracture load and failure mode of glass ceramic crowns.

PubMed

Mores, Rafael Tagliari; Borba, Márcia; Corazza, Pedro Henrique; Della Bona, Álvaro; Benetti, Paula

2017-10-01

Ceramic restorations often require adjustments using diamond rotary instruments, which damage the glazed surface. The effect of these adjustments on the fracture behavior of these restorations is unclear. The purpose of this in vitro study was to evaluate the influence of induced surface defects on the fracture load and mode of failure of lithium disilicate-based (LDS) glass ceramic restorations. Premolar crowns were obtained from LDS computer-aided design and computer-aided manufacturing blocks (n=60) and glazed. The crowns were bonded to dentin analog dies and divided into 5 groups (n=12), as follows: glaze; abrasion (diamond rotary instrument 2135); abrasion and reglaze; abrasion and polishing (diamond rotary instrument 2135F, 2135 FF, and polishing devices); and polishing. The topography of the crowns was examined by scanning electron microscopy, and roughness was measured. A compressive load (0.5 mm/min) was applied by a piston to the center of the lingual cusp until fracture. The fracture load was recorded and data were statistically analyzed by ANOVA and the Tukey HSD test (α=.05). Fractured crowns were examined to determine the fracture origin. Polishing and/or reglazing resulted in lower roughness than for the abraded group (P<.05), which did not affect the fracture loads (P=.696). Catastrophic fracture with origin at the intaglio surface was the mode of failure for all the crowns. The experiment design successfully submitted the crowns to a clinical stress state, resulting in a clinically relevant failure. Reglazing or polishing were effective in reducing surface defects. Surface treatments had no effect on the immediate catastrophic failure of LDS crowns. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Evaluation of the onset of failure under mechanical and thermal stresses on luting agent for metal–ceramic and metal crowns by finite element analysis

PubMed Central

Agnihotri, Hema; Bhatnagar, Naresh; Rao, G. Venugopal; Jain, Veena; Parkash, Hari; Kar, Aswini Kumar

2010-01-01

Long-term clinical failures of cemented prosthesis depend, to a large extent, on the integrity of the luting agent. The causative factors that lead to microfracture and, hence, failure of the luting agents are the stresses acting inside the oral cavity. Therefore, the present study was designed to develop an understanding of the relationship between stresses in the tooth and the failure potential of the luting agent. Two-dimensional finite element stress analysis was performed on the mandibular second premolar. The behavior of zinc-phosphate and glass-ionomer were studied under different crowns (metal–ceramic and metal crown) and loading conditions (mechanical force of 450 N acting vertically over the occlusal surface, thermal loads of 60° and 0°C). It was observed from the study that failure threshold of the luting agent was influenced both by the elastic modulus of the luting agent and by the type of the crown. PMID:22114426

Forecasting wildland fire behavior using high-resolution large-eddy simulations

NASA Astrophysics Data System (ADS)

Munoz-Esparza, D.; Kosovic, B.; Jimenez, P. A.; Anderson, A.; DeCastro, A.; Brown, B.

2016-12-01

Wildland fires are responsible for large socio-economic impacts. Fires affect the environment, damage structures, threaten lives, cause health issues, and involve large suppression costs. These impacts can be mitigated via accurate fire spread forecast to inform the incident management team. To this end, the state of Colorado is funding the development of the Colorado Fire Prediction System (CO-FPS). The system is based on the Weather Research and Forecasting (WRF) model enhanced with a fire behavior module (WRF-Fire). Realistic representation of wildland fire behavior requires explicit representation of small scale weather phenomena to properly account for coupled atmosphere-wildfire interactions. Moreover, transport and dispersion of biomass burning emissions from wildfires is controlled by turbulent processes in the atmospheric boundary layer, which are difficult to parameterize and typically lead to large errors when simplified source estimation and injection height methods are used. Therefore, we utilize turbulence-resolving large-eddy simulations at a resolution of 111 m to forecast fire spread and smoke distribution using a coupled atmosphere-wildfire model. This presentation will describe our improvements to the level-set based fire-spread algorithm in WRF-Fire and an evaluation of the operational system using 12 wildfire events that occurred in Colorado in 2016, as well as other historical fires. In addition, the benefits of explicit representation of turbulence for smoke transport and dispersion will be demonstrated.

Forecasting wildland fire behavior using high-resolution large-eddy simulations

NASA Astrophysics Data System (ADS)

Munoz-Esparza, D.; Kosovic, B.; Jimenez, P. A.; Anderson, A.; DeCastro, A.; Brown, B.

2017-12-01

Wildland fires are responsible for large socio-economic impacts. Fires affect the environment, damage structures, threaten lives, cause health issues, and involve large suppression costs. These impacts can be mitigated via accurate fire spread forecast to inform the incident management team. To this end, the state of Colorado is funding the development of the Colorado Fire Prediction System (CO-FPS). The system is based on the Weather Research and Forecasting (WRF) model enhanced with a fire behavior module (WRF-Fire). Realistic representation of wildland fire behavior requires explicit representation of small scale weather phenomena to properly account for coupled atmosphere-wildfire interactions. Moreover, transport and dispersion of biomass burning emissions from wildfires is controlled by turbulent processes in the atmospheric boundary layer, which are difficult to parameterize and typically lead to large errors when simplified source estimation and injection height methods are used. Therefore, we utilize turbulence-resolving large-eddy simulations at a resolution of 111 m to forecast fire spread and smoke distribution using a coupled atmosphere-wildfire model. This presentation will describe our improvements to the level-set based fire-spread algorithm in WRF-Fire and an evaluation of the operational system using 12 wildfire events that occurred in Colorado in 2016, as well as other historical fires. In addition, the benefits of explicit representation of turbulence for smoke transport and dispersion will be demonstrated.

Simulating Fire Disturbance and Plant Mortality Using Antecedent Eco-hydrological Conditions to Inform a Physically Based Combustion Model

NASA Astrophysics Data System (ADS)

Atchley, A. L.; Linn, R.; Middleton, R. S.; Runde, I.; Coon, E.; Michaletz, S. T.

2016-12-01

Wildfire is a complex agent of change that both affects and depends on eco-hydrological systems, thereby constituting a tightly linked system of disturbances and eco-hydrological conditions. For example, structure, build-up, and moisture content of fuel are dependent on eco-hydrological regimes, which impacts fire spread and intensity. Fire behavior, on the other hand, determines the severity and extent of eco-hydrological disturbance, often resulting in a mosaic of untouched, stressed, damaged, or completely destroyed vegetation within the fire perimeter. This in turn drives new eco-hydrological system behavior. The cycles of disturbance and recovery present a complex evolving system with many unknowns especially in the face of climate change that has implications for fire risk, water supply, and forest composition. Physically-based numerical experiments that attempt to capture the complex linkages between eco-hydrological regimes that affect fire behavior and the echo-hydrological response from those fire disturbances help build the understanding required to project how fire disturbance and eco-hydrological conditions coevolve over time. Here we explore the use of FIRETEC—a physically-based 3D combustion model that solves conservation of mass, momentum, energy, and chemical species—to resolve fire spread over complex terrain and fuel structures. Uniquely, we couple a physically-based plant mortality model with FIRETEC and examine the resultant hydrologic impact. In this proof of concept demonstration we spatially distribute fuel structure and moisture content based on the eco-hydrological condition to use as input for FIRETEC. The fire behavior simulation then produces localized burn severity and heat injures which are used as input to a spatially-informed plant mortality model. Ultimately we demonstrate the applicability of physically-based models to explore integrated disturbance and eco-hydrologic response to wildfire behavior and specifically map how fire spread and intensity is affect by the antecedent eco-hydrological condition, which then affects the resulting tree mortality patterns.

Wildfires

MedlinePlus

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Fire behavior and risk analysis in spacecraft

NASA Technical Reports Server (NTRS)

Friedman, Robert; Sacksteder, Kurt R.

1988-01-01

Practical risk management for present and future spacecraft, including space stations, involves the optimization of residual risks balanced by the spacecraft operational, technological, and economic limitations. Spacecraft fire safety is approached through three strategies, in order of risk: (1) control of fire-causing elements, through exclusion of flammable materials for example; (2) response to incipient fires through detection and alarm; and (3) recovery of normal conditions through extinguishment and cleanup. Present understanding of combustion in low gravity is that, compared to normal gravity behavior, fire hazards may be reduced by the absence of buoyant gas flows yet at the same time increased by ventilation flows and hot particle expulsion. This paper discusses the application of low-gravity combustion knowledge and appropriate aircraft analogies to fire detection, fire fighting, and fire-safety decisions for eventual fire-risk management and optimization in spacecraft.

Information-Seeking and Sharing Behaviors among Fire Service Field Staff Instructors: A Qualitative Study

ERIC Educational Resources Information Center

Ruan, Lian J.

2011-01-01

Fire service field staff instructors seek and share information and use information sources during their instructional work of teaching, training and curriculum development. This study is the first attempt to study their information-seeking and sharing behaviors, which have not previously been investigated empirically. Twenty-five fire service…

Fire Return Interval Within the Northern Boundary of the Larch Forest

NASA Technical Reports Server (NTRS)

Kharuk, V. I.; Dvinskaya, M. L.; Ranson, K. J.

2011-01-01

Larch (Larix spp.) dominant forests compose a large proportion of the forests of Russia (i.e., about 40% of forested areas). These forests range from the Yenisei ridge on the west to the Pacific Ocean on the east, and from Lake Baikal on the south to the 73rd parallel in the north. Larch stands comprise the world s northern most forest at Ary-Mas (72 deg 28' N, 102 deg 15' E). Larch dominated forests occupy about 70% of the permafrost areas in Siberia. Larch forms high closure stands as well as open forests, and is found mainly over permafrost, where other tree species barely survive. Wildfires are typical for this territory with the majority occurring as ground fires due to low crown closure. Due to the thin active layer in permafrost soils and a dense lichen-moss cover, ground fires may cause stand mortality. The vast areas of larch-dominant forests is generally considered as a "carbon sink"; however, positive long-term temperature trends at higher latitudes are expected to result in an increase of fire frequency, and thus may convert this area to a source for greenhouse gases. There are recent observations regarding the increase of fire frequency within non-protected territories. Surprisingly, there are few publications on fire chronoseqences for the huge forested territory between the Ural Mountains and the Pacific Ocean. Also there is a general understanding that bimodal (late spring -- early summer and late summer-beginning of fall) fire seasonal distribution in the south becomes uni-modal (late spring -- early summer) in the north. The purpose of this study is to investigate the wildfire history at the northern edge of the zone of larch dominance.

Could managed burning of peatlands lead to carbon storage?

NASA Astrophysics Data System (ADS)

Clay, G.; Worrall, F.

2007-12-01

Peatlands are the UK's largest single terrestrial carbon store with carbon stored in UK peatlands than in forests of Britain and France combined. Unlike most northern peatlands in the peat soils of the UK are heavily managed for recreation and agriculture and due to their proximity to major centres of population are under more anthropogenic pressure than most peatlands. A typical management strategy on UK upland peats is the use of managed fire to restrict vegetation. Fires are used upon a 10-25 year rotation and are described as "cool" as they remove the crown of the vegetation without scorching the litter layer or the underlying soil. In this case the fire destroys primary productivity and limits litter production but produces char. Char is a low volume, highly refractory, high carbon content product while litter is a high volume, decomposable, lower carbon content product. Therefore, the question is if there are fire conditions underwhich the production of char causes more carbon to be stored in the peat than would have been stored if no fire management had been employed. This study uses detailed vegetation studies from a long term monitoring site in order to assess litter and biomass production; in laboratory experimental burns were undertaken in order to assess the amount and controls upon char production and the carbon content of that char. Results of field and laboratory observations are used to model carbon accumulation under s aseries of fire management scenarios and the modelling shows that cools burns at long rotations could lead to higher carbon storage than if no fire had occurred, further than in several cases more carbon accumulation occurred even if less depth of peat was generated.

Could managed burning of peatlands lead to enhanced carbon storage?

NASA Astrophysics Data System (ADS)

Worrall, F.; Clay, G. D.

2009-04-01

Peatlands are the UK's largest single terrestrial carbon store with carbon stored in UK peatlands than in forests of Britain and France combined. Unlike most northern peatlands in the peat soils of the UK are heavily managed for recreation and agriculture and due to their proximity to major centres of population are under more anthropogenic pressure than most peatlands. A typical management strategy on UK upland peats is the use of managed fire to restrict vegetation. Fires are used upon a 10-25 year rotation and are described as "cool" as they are designed to remove the crown of the vegetation without scorching the litter layer or the underlying soil. In this case the fire destroys primary productivity and limits litter production but produces char. Char is a low volume, highly refractory, high carbon content product while litter is a high volume, decomposable, lower carbon content product. Therefore, the question is if there are fire conditions under which the production of char causes more carbon to be stored in the peat than would have been stored if no fire management had been employed. This study combines field studies of recent managed burns and wildfires along with detailed vegetation studies from a long term monitoring site in order to assess litter, biomass and black carbon production. In the laboratory experimental burns were undertaken in order to assess the amount and controls upon char production and the carbon content of that char. Results of field and laboratory observations are used to model carbon accumulation under a series of fire management scenarios and the modelling shows that cools burns at long rotations could lead to higher carbon storage than if no fire had occurred, further in several cases more carbon accumulation occurred even if less depth of peat was generated.

A multi-scale conceptual model of fire and disease interactions in North American forests

NASA Astrophysics Data System (ADS)

Varner, J. M.; Kreye, J. K.; Sherriff, R.; Metz, M.

2013-12-01

One aspect of global change with increasing attention is the interactions between irruptive pests and diseases and wildland fire behavior and effects. These pests and diseases affect fire behavior and effects in spatially and temporally complex ways. Models of fire and pathogen interactions have been constructed for individual pests or diseases, but to date, no synthesis of this complexity has been attempted. Here we synthesize North American fire-pathogen interactions into syndromes with similarities in spatial extent and temporal duration. We base our models on fire interactions with three examples: sudden oak death (caused by the pathogen Phytopthora ramorum) and the native tree tanoak (Notholithocarpus densiflorus); mountain pine beetle (Dendroctonus ponderosae) and western Pinus spp.; and hemlock woolly adelgid (Adelges tsugae) on Tsuga spp. We evaluate each across spatial (severity of attack from branch to landscape scale) and temporal scales (from attack to decades after) and link each change to its coincident effects on fuels and potential fire behavior. These syndromes differ in their spatial and temporal severity, differentially affecting windows of increased or decreased community flammability. We evaluate these models with two examples: the recently emergent ambrosia beetle-vectored laurel wilt (caused by the pathogen Raffaelea lauricola) in native members of the Lauraceae and the early 20th century chestnut blight (caused by the pathogen Cryphonectria parasitica) that led to the decline of American chestnut (Castanea dentata). Some changes (e.g., reduced foliar moisture content) have short-term consequences for potential fire behavior while others (functional extirpation) have more complex indirect effects on community flammability. As non-native emergent diseases and pests continue, synthetic models that aid in prediction of fire behavior and effects will enable the research and management community to prioritize mitigation efforts to realized effects.

Social Desirability and Behavior Rating Scales: An Exploratory Study with the Child Behavior Checklist/4-18

ERIC Educational Resources Information Center

Merydith, Scott P.; Prout, H. Thompson; Blaha, John

2003-01-01

This study investigated the relationship between the Child Behavior Checklist/4-18 (CBCL/4-18) and two modified measures of social desirability, the Marlowe-Crowne Social Desirability Scale and the Edwards Social Desirability Scale with a sample of 65 parents of normal children from grades K-7. Results from correlational and multiple regression…

Relationships between tree size, crown shape, gender segregation and sex allocation in Pinus halepensis, a Mediterranean pine tree.

PubMed

Ne'eman, Gidi; Goubitz, Shirrinka; Werger, Marinus J A; Shmida, Avi

2011-07-01

Sex allocation has been studied mainly in small herbaceous plants but much less in monoecious wind-pollinated trees. The aim of this study was to explore changes in gender segregation and sex allocation by Pinus halepensis, a Mediterranean lowland pine tree, within tree crowns and between trees differing in their size or crown shape. The production of new male and female cones and sex allocation of biomass, nitrogen and phosphorus were studied. The relationship between branch location, its reproductive status and proxies of branch vigour was also studied. Small trees produced only female cones, but, as trees grew, they produced both male and female cones. Female cones were produced mainly in the upper part of the crown, and male cones in its middle and lower parts. Lateral branch density was correlated with the number of male but not female cones; lateral branches were more dense in large than in small trees and even denser in hemispherical trees. Apical branches grew faster, were thicker and their phosphorus concentration was higher than in lateral shoots. Nitrogen concentration was higher in cone-bearing apical branches than in apical vegetative branches and in lateral branches with or without cones. Allocation to male relative to female function increased with tree size as predicted by sex allocation theory. The adaptive values of sex allocation and gender segregation patterns in P. halepensis, in relation to its unique life history, are demonstrated and discussed. Small trees produce only female cones that have a higher probability of being pollinated than the probability of male cones pollinating; the female-first strategy enhances population spread. Hemispherical old trees are loaded with serotinous cones that supply enough seeds for post-fire germination; thus, allocation to males is more beneficial than to females.

Brief communication: Reaction to fire by savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal: Conceptualization of "fire behavior" and the case for a chimpanzee model.

PubMed

Pruetz, Jill D; LaDuke, Thomas C

2010-04-01

The use and control of fire are uniquely human traits thought to have come about fairly late in the evolution of our lineage, and they are hypothesized to correlate with an increase in intellectual complexity. Given the relatively sophisticated cognitive abilities yet small brain size of living apes compared to humans and even early hominins, observations of wild chimpanzees' reactions to naturally occurring fire can help inform hypotheses about the likely responses of early hominins to fire. We use data on the behavior of savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal during two encounters with wildfires to illuminate the similarities between great apes and humans regarding their reaction to fire. Chimpanzees' close relatedness to our lineage makes them phylogenetically relevant to the study of hominid evolution, and the open, hot and dry environment at Fongoli, similar to the savanna mosaic thought to characterize much of hominid evolution, makes these apes ecologically important as a living primate model as well. Chimpanzees at Fongoli calmly monitor wildfires and change their behavior in anticipation of the fire's movement. The ability to conceptualize the "behavior" of fire may be a synapomorphic trait characterizing the human-chimpanzee clade. If the cognitive underpinnings of fire conceptualization are a primitive hominid trait, hypotheses concerning the origins of the control and use of fire may need revision. We argue that our findings exemplify the importance of using living chimpanzees as models for better understanding human evolution despite recently published suggestions to the contrary. (c) 2009 Wiley-Liss, Inc.

Inaja Fire - 1956, Pine Hills Fire - 1967...similar, yet different

Treesearch

Mark J. Schroeder; Bernadine B. Taylor

1968-01-01

Two fires burned in the same area in southern California under nearly similar weather conditions, 11 years apart. Yet the Inaja fire of 1956 was much more disastrous than the Pine Hills fire of 1967. The earlier fire claimed 11 lives, and covered an area five times larger than the 1967 fire. Differences in fuels, topography, fire behavior, fire-control action, and...

An unusual case of random fire-setting behavior associated with lacunar stroke.

PubMed

Bosshart, Herbert; Capek, Sonia

2011-06-15

A case of a 47-year-old man with a sudden onset of a bizarre and random fire-setting behavior is reported. The man, who had been arrested on felony arson charges, complained of difficulties concentrating and of recent memory impairment. Axial T1-weighted magnetic resonance imaging showed a low intensity lacunar lesion in the genu and anterior limb of the left internal capsule. A neuropsychological test battery revealed lower than normal scores for executive functions, attention and memory, consistent with frontal lobe dysfunction. The recent onset of fire-setting behavior and the chronic nature of the lacunar lesion, together with an unremarkable performance on tests measuring executive functions two years prior, suggested a causal relationship between this organic brain lesion and the fire-setting behavior. The present case describes a rare and as yet unreported association between random impulse-driven fire-setting behavior and damage to the left internal capsule and suggests a disconnection of frontal lobe structures as a possible pathogenic mechanism. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Mountain Pine Beetle Dynamics and Reproductive Success in Post-Fire Lodgepole and Ponderosa Pine Forests in Northeastern Utah

PubMed Central

Lerch, Andrew P.; Pfammatter, Jesse A.

2016-01-01

Fire injury can increase tree susceptibility to some bark beetles (Curculionidae, Scolytinae), but whether wildfires can trigger outbreaks of species such as mountain pine beetle (Dendroctonus ponderosae Hopkins) is not well understood. We monitored 1173 lodgepole (Pinus contorta var. latifolia Doug.) and 599 ponderosa (Pinus ponderosa Doug. ex Law) pines for three years post-wildfire in the Uinta Mountains of northeastern Utah in an area with locally endemic mountain pine beetle. We examined how the degree and type of fire injury influenced beetle attacks, brood production, and subsequent tree mortality, and related these to beetle population changes over time. Mountain pine beetle population levels were high the first two post-fire years in lodgepole pine, and then declined. In ponderosa pine, populations declined each year after initial post-fire sampling. Compared to trees with strip or failed attacks, mass attacks occurred on trees with greater fire injury, in both species. Overall, a higher degree of damage to crowns and boles was associated with higher attack rates in ponderosa pines, but additional injury was more likely to decrease attack rates in lodgepole pines. In lodgepole pine, attacks were initially concentrated on fire-injured trees, but during subsequent years beetles attacked substantial numbers of uninjured trees. In ponderosa pine, attacks were primarily on injured trees each year, although these stands were more heavily burned and had few uninjured trees. In total, 46% of all lodgepole and 56% of ponderosa pines underwent some degree of attack. Adult brood emergence within caged bole sections decreased with increasing bole char in lodgepole pine but increased in ponderosa pine, however these relationships did not scale to whole trees. Mountain pine beetle populations in both tree species four years post-fire were substantially lower than the year after fire, and wildfire did not result in population outbreaks. PMID:27783632

Mountain Pine Beetle Dynamics and Reproductive Success in Post-Fire Lodgepole and Ponderosa Pine Forests in Northeastern Utah.

PubMed

Lerch, Andrew P; Pfammatter, Jesse A; Bentz, Barbara J; Raffa, Kenneth F

2016-01-01

Fire injury can increase tree susceptibility to some bark beetles (Curculionidae, Scolytinae), but whether wildfires can trigger outbreaks of species such as mountain pine beetle (Dendroctonus ponderosae Hopkins) is not well understood. We monitored 1173 lodgepole (Pinus contorta var. latifolia Doug.) and 599 ponderosa (Pinus ponderosa Doug. ex Law) pines for three years post-wildfire in the Uinta Mountains of northeastern Utah in an area with locally endemic mountain pine beetle. We examined how the degree and type of fire injury influenced beetle attacks, brood production, and subsequent tree mortality, and related these to beetle population changes over time. Mountain pine beetle population levels were high the first two post-fire years in lodgepole pine, and then declined. In ponderosa pine, populations declined each year after initial post-fire sampling. Compared to trees with strip or failed attacks, mass attacks occurred on trees with greater fire injury, in both species. Overall, a higher degree of damage to crowns and boles was associated with higher attack rates in ponderosa pines, but additional injury was more likely to decrease attack rates in lodgepole pines. In lodgepole pine, attacks were initially concentrated on fire-injured trees, but during subsequent years beetles attacked substantial numbers of uninjured trees. In ponderosa pine, attacks were primarily on injured trees each year, although these stands were more heavily burned and had few uninjured trees. In total, 46% of all lodgepole and 56% of ponderosa pines underwent some degree of attack. Adult brood emergence within caged bole sections decreased with increasing bole char in lodgepole pine but increased in ponderosa pine, however these relationships did not scale to whole trees. Mountain pine beetle populations in both tree species four years post-fire were substantially lower than the year after fire, and wildfire did not result in population outbreaks.

Quantifying post-fire fallen trees using multi-temporal lidar

NASA Astrophysics Data System (ADS)

Bohlin, Inka; Olsson, Håkan; Bohlin, Jonas; Granström, Anders

2017-12-01

Massive tree-felling due to root damage is a common fire effect on burnt areas in Scandinavia, but has so far not been analyzed in detail. Here we explore if pre- and post-fire lidar data can be used to estimate the proportion of fallen trees. The study was carried out within a large (14,000 ha) area in central Sweden burnt in August 2014, where we had access to airborne lidar data from both 2011 and 2015. Three data-sets of predictor variables were tested: POST (post-fire lidar metrics), DIF (difference between post- and pre-fire lidar metrics) and combination of those two (POST_DIF). Fractional logistic regression was used to predict the proportion of fallen trees. Training data consisted of 61 plots, where the number of fallen and standing trees was calculated both in the field and with interpretation of drone images. The accuracy of the best model was tested based on 100 randomly selected validation plots with a size of 25 × 25 m. Our results showed that multi-temporal lidar together with field-collected training data can be used for quantifying post-fire tree felling over large areas. Several height-, density- and intensity metrics correlated with the proportion of fallen trees. The best model combined metrics from both datasets (POST_DIF), resulting in a RMSE of 0.11. Results were slightly poorer in the validation plots with RMSE of 0.18 using pixel size of 12.5 m and RMSE of 0.15 using pixel size of 6.25 m. Our model performed least well for stands that had been exposed to high-intensity crown fire. This was likely due to the low amount of echoes from the standing black tree skeletons. Wall-to-wall maps produced with this model can be used for landscape level analysis of fire effects and to explore the relationship between fallen trees and forest structure, soil type, fire intensity or topography.

Investigation on the preparation and chromatographic behavior of a new para-tert-butylcalix[4]arene-1,2-crown-4 stationary phase for high performance liquid chromatography.

PubMed

Hu, Kai; Zhao, Wenjie; Wen, Fuyong; Liu, Junwei; Zhao, Xiaolan; Xu, Zhanhui; Niu, Bailin; Ye, Baoxian; Wu, Yangjie; Zhang, Shusheng

2011-07-15

In the present work, a new para-tert-butylcalix[4]arene-1,2-crown-4 bonded silica stationary phase (CBS4-4) was synthesized, structurally characterized, and employed to separate polycyclic aromatic hydrocarbons (PAHs), phenols, aromatic amines, benzoic acid and its derivatives. The chromatographic behaviors of the prepared stationary phase were investigated and compared with ODS. The effects of methanol concentrations on the retention index show that CBS4-4 exhibits high selectivity for the above analytes. The separation mechanisms based on the different interactions between calixarene and the analytes were discussed. With the assistance of quantum chemistry calculation, the interaction Gibbs free energy change ΔG(solv) (in the mobile phase) of p, m and o-phenylenediamine positional isomers and para-tert-butylcalix[4]arene-1,2-crown-4 were obtained. The ΔG(solv) values were consistent with the retention behavior of p, m and o-phenylenediamine on the CBS4-4. According to the chromatographic data, it can be concluded that the selectivity of CBS4-4 for analytes is mainly ascribed to hydrophobic interaction, accompanied by other effects such as hydrogen bonding interaction, π-π and inclusion interaction. The CBS4-4 column has been successfully employed for the analysis of benzoic acid in Sprite drink. Copyright © 2011 Elsevier B.V. All rights reserved.

A review of fire interactions and mass fires

Treesearch

Mark A. Finney; Sara S. McAllister

2011-01-01

The character of a wildland fire can change dramatically in the presence of another nearby fire. Understanding and predicting the changes in behavior due to fire-fire interactions cannot only be life-saving to those on the ground, but also be used to better control a prescribed fire to meet objectives. In discontinuous fuel types, such interactions may elicit fire...

FireWorks educational program and its effectiveness

Treesearch

Jane Kapler Smith; Nancy E. McMurray

2004-01-01

FireWorks is an educational program that provides interactive, hands-on activities for studying fire behavior, fire ecology, and human influences on three fire-dependent forest types-ponderosa pine (Pinus ponderosa), interior lodgepolepine (P. contorta var.latifolia), and whitebark pine (P. albicaulis)....

Modeling tree crown dynamics with 3D partial differential equations.

PubMed

Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry

2014-01-01

We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

Selection of fire spread model for Russian fire behavior prediction system

Treesearch

Alexandra V. Volokitina; Kevin C. Ryan; Tatiana M. Sofronova; Mark A. Sofronov

2010-01-01

Mathematical modeling of fire behavior prediction is only possible if the models are supplied with an information database that provides spatially explicit input parameters for modeled area. Mathematical models can be of three kinds: 1) physical; 2) empirical; and 3) quasi-empirical (Sullivan, 2009). Physical models (Grishin, 1992) are of academic interest only because...

Intrapsychic dynamics, behavioral manifestations, and related interventions with youthful fire setters.

PubMed

Williams, Dian L; Clements, Paul T

2007-01-01

Fire setting in youth has often been overlooked and misunderstood as a coping skill for expressing rage. The act of deliberate fire setting, if uninterrupted, may continue throughout an individual's lifetime. Forensic examiners, mental health care providers, and criminal justice professionals can help guide referral and treatment through better understanding of behaviors and intrapsychic dynamics.

Nomographs for estimating surface fire behavior characteristics

Treesearch

Joe H. Scott

2007-01-01

A complete set of nomographs for estimating surface fire rate of spread and flame length for the original 13 and new 40 fire behavior fuel models is presented. The nomographs allow calculation of spread rate and flame length for wind in any direction with respect to slope and allow for nonheading spread directions. Basic instructions for use are included.

Invasive grasses change landscape structure and fire behavior in Hawaii

Treesearch

Lisa M. Ellsworth; Creighton M. Litton; Alexander P. Dale; Tomoaki Miura

2014-01-01

How does potential fire behavior differ in grass-invaded non-native forests vs open grasslands? How has land cover changed from 1950–2011 along two grassland/forest ecotones in Hawaii with repeated fires? A study on non-native forest with invasive grass understory and invasive grassland (Megathyrsus maximus) ecosystems on Oahu, Hawaii, USA was...

Use of Video Modeling to Teach Extinguishing of Cooking Related Fires to Individuals with Moderate Intellectual Disabilities

ERIC Educational Resources Information Center

Mechling, Linda C.; Gast, David L.; Gustafson, Melissa R.

2009-01-01

This study evaluated the effectiveness of video modeling to teach fire extinguishing behaviors to three young adults with moderate intellectual disabilities. A multiple probe design across three fire extinguishing behaviors and replicated across three students was used to evaluate the effectiveness of the video-based program. Results indicate that…

Establishing Fire Safety Skills Using Behavioral Skills Training

ERIC Educational Resources Information Center

Houvouras, Andrew J., IV; Harvey, Mark T.

2014-01-01

The use of behavioral skills training (BST) to educate 3 adolescent boys on the risks of lighters and fire setting was evaluated using in situ assessment in a school setting. Two participants had a history of fire setting. After training, all participants adhered to established rules: (a) avoid a deactivated lighter, (b) leave the training area,…

Fuel treatment longevity in a Sierra Nevada mixed conifer forest

Treesearch

Scott. L. Stephens; Brandon M. Collins; Gary. Roller

2012-01-01

Understanding the longevity of fuel treatments in terms of their ability to maintain fire behavior and effects within a desired range is an important question. The objective of this study was to determine how fuels, forest structure, and predicted fire behavior changed 7-years after initial treatments. Three different treatments: mechanical only, mechanical plus fire,...

Early fire history near Papineau lake, Ontario

Treesearch

Daniel C. Dey; Richard P. Guyette

1996-01-01

Research that defines the role of fire in upland red oak-pine ecosystems in central Ontario is being conducted by the Great Lakes-St. Lawrence Silviculture program. Site-specific fire histories are being developed that document fire frequency, fire behavior, fire effects on forest regeneration and grwoth, and the influnce of human activites on fire disturbances. This...

Forecasting distribution of numbers of large fires

Treesearch

Haiganoush K. Preisler; Jeff Eidenshink; Stephen Howard; Robert E. Burgan

2015-01-01

Systems to estimate forest fire potential commonly utilize one or more indexes that relate to expected fire behavior; however they indicate neither the chance that a large fire will occur, nor the expected number of large fires. That is, they do not quantify the probabilistic nature of fire danger. In this work we use large fire occurrence information from the...

Electric ants: A cross-disciplinary approach to understanding insect behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slowik, T.J.; Thorvilson, H.G.; Green, B.L.

1996-12-31

The response and attraction of the red imported fire ant, Solenopsis invicta, to electrical equipment was examined using an interdisciplinary approach. Entomologists specializing in fire ant behavior combined expertise with electrical engineers to investigate the economically damaging interaction of fire ants with electrical circuitry. Knowledge from the realms of physics, engineering, and biology were integrated in experimentation to test for a fire ant response to electric fields and magnetic fields associated with electrical equipment. It was determined that fire ants react to electrified conductive material and the alternating-current magnetic fields associated with electricity.

Fire hazards at the urban-wildland interface: What the public expects

NASA Astrophysics Data System (ADS)

Cortner, Hanna J.; Gardner, Philip D.; Taylor, Jonathan G.

1990-01-01

Urban-wildland issues have become among the most contentious and problematic issues for forest managers. Using data drawn from surveys conducted by the authors and others, this article discusses how public knowledge and perceptions of fire policies and fire hazards change over time, the kinds of policy responses homeowners prefer as a way of preventing fire hazards at the urban-wildland interface, and how citizens view their own obligations as participants in interface issues. These data show that public attitudes toward fire have changed significantly over the past two decades and that educating the public about fire and the managers' use of fire can have positive effects on behavior. Yet, modifying the individual's behavior in regard to interface fire risks must also deal with important issues of individual incentives, the distribution of costs, and unanticipated policy impacts.

Fire hazards at the urban-wildland interface: what the public expects

USGS Publications Warehouse

Cortner, Hanna J.; Gardner, Philip D.; Taylor, Jonathan G.

1990-01-01

Urban-wildland issues have become among the most contentious and problematic issues for forest managers. Using data drawn from surveys conducted by the authors and others, this article discusses how public knowledge and perceptions of fire policies and fire hazards change over time, the kinds of policy responses homeowners prefer as a way of preventing fire hazards at the urban-wildland interface, and how citizens view their own obligations as participants in interface issues. These data show that public attitudes toward fire have changed significantly over the past two decades and that educating the public about fire and the managers' use of fire can have positive effects on behavior. Yet, modifying the individual's behavior in regard to interface fire risks must also deal with important issues of individual incentives, the distribution of costs, and unanticipated policy impacts.

Prevalence and correlates of fire-setting in the United States: results from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC).

PubMed

Blanco, Carlos; Alegría, Analucía A; Petry, Nancy M; Grant, Jon E; Simpson, H Blair; Liu, Shang-Min; Grant, Bridget F; Hasin, Deborah S

2010-09-01

To estimate the prevalence, sociodemographic correlates, comorbidity, and rates of mental health service utilization of fire-setters in the general population. A face-to-face survey of more than 43,000 adults aged 18 years and older residing in households was conducted during the 2001-2002 period. Diagnoses of mood, anxiety, substance use disorders, and personality disorders were based on the Alcohol Use Disorder and Associated Disabilities Interview Schedule-DSM-IV Version (AUDADIS-IV). The prevalence of lifetime fire-setting in the US population was 1.13 (95% CI, 1.0-1.3). Being male, never married, and US-born and having a yearly income over $70,000 were risk factors for lifetime fire-setting, while being Asian or Hispanic and older than 30 years were protective factors for lifetime fire-setting. The strongest associations with fire-setting were with disorders often associated with deficits in impulse control, such as antisocial personality disorder (ASPD) (odds ratio [OR] = 21.8; CI, 6.6-28.5), drug dependence (OR = 7.6; 95% CI, 5.2-10.9), bipolar disorder (OR = 5.6; 95% CI, 4.0-7.9), and pathological gambling (OR = 4.8; 95% CI, 2.4-9.5). Associations between fire-setting and all antisocial behaviors were positive and significant. A lifetime history of fire-setting, even in the absence of an ASPD diagnosis, was strongly associated with substantial rates of Axis I comorbidity, a history of antisocial behavior, a family history of other antisocial behaviors, decreased functioning, and higher treatment-seeking rates. Our findings suggest that fire-setting may be better understood as a behavioral manifestation of a broader impaired control syndrome and part of the externalizing spectrum. Fire-setting and other antisocial behaviors tend to be strongly associated with each other and increase the risk of lifetime and current psychiatric disorders, even in the absence of a DSM-IV diagnosis of ASPD. © Copyright 2010 Physicians Postgraduate Press, Inc.

Characterizing Early Succession Following Wildfires at Different Severities in Boreal Bog and Fen Peatlands

NASA Astrophysics Data System (ADS)

Ernst, E. J.; Bourgeau-Chavez, L. L.; Kane, E. S.; Wagenbrenner, J. W.; Endres, S.

2016-12-01

The Arctic-boreal region is experiencing changes in climate, trending toward warmer summers, resulting in a greater occurrence of wildfires with longer burning periods and higher intensities. Drought-like conditions have dried surface fuels, leading to a higher probability of ignition, even in lowland peatlands. Previous work has been done to characterize post-fire succession rates in Arctic-boreal upland sites, but much less is known of fire effects and early successional dynamics in lowlands. Wildland fires are the number one disturbance in Canada's Northwest Territories (NWT), which characteristically burn at high intensities with large flame fronts, and result in some of the biggest wildfires in the world. Areas surrounding the Great Slave Lake, NWT—including parts of the Taiga Plains, Taiga Shield, and Boreal Plains ecozones—experienced exceptional wildfire activity in 2014 and 2015. We characterized burn severity of the bog and fen peat surface and canopy layers at several burned sites. To determine if the severe ground or crown wildfires were stand-replacing events, we characterized post-fire vegetation in peatlands in 2015 and 2016 based on seedling regeneration. We stratified sites according to estimated water residence times across the three ecozones and made comparisons between data collected at the same sites across years. This work adds much needed context for post-fire succession in boreal peatland ecosystems, as the susceptibility of these systems to burning will continue to increase with a warming climate.

Inferring differential evolutionary processes of plant persistence traits in Northern Hemisphere Mediterranean fire-prone ecosystems

USGS Publications Warehouse

Pausas, J.G.; Keeley, J.E.; Verdu, M.

2006-01-01

1 Resprouting capacity (R) and propagule-persistence (P) are traits that are often considered to have evolved where there are predictable crown fires. Because several indicators suggest a stronger selective pressure for such traits in California than in the Mediterranean Basin, we hypothesize that plant species should have evolved to become R+ and P+ more frequently in California than in the Mediterranean Basin. 2 To test this hypothesis we studied the phylogenetic association between R and P states in both California and the Mediterranean Basin using published molecular phylogenies. 3 The results suggest that R and P evolved differently in the two regions. The occurrence of the states differs significantly between regions for trait P, but not for trait R. The different patterns (towards R+ and P+ in California and towards R+ and P- in the Mediterranean Basin) are reflected in the higher abundance and the wider taxonomic distribution of species with both persistence traits (R+P+ species) in California. 4 The differential acquisition of fire persistence mechanisms at the propagule level (P+) supports the idea that fire selective pressures has been higher in California than in the Mediterranean Basin. 5 Our comparative phylogenetic-informed analysis contributes to an understanding of the differential role of the Quaternary climate in determining fire persistence traits in different Mediterranean-type ecosystems and, thus, to the debate on the evolutionary convergence of traits. ?? 2006 British Ecological Society.

A method for mapping fire hazard and risk across multiple scales and its application in fire management

Treesearch

Robert E. Keane; Stacy A. Drury; Eva C. Karau; Paul F. Hessburg; Keith M. Reynolds

2010-01-01

This paper presents modeling methods for mapping fire hazard and fire risk using a research model called FIREHARM (FIRE Hazard and Risk Model) that computes common measures of fire behavior, fire danger, and fire effects to spatially portray fire hazard over space. FIREHARM can compute a measure of risk associated with the distribution of these measures over time using...

The Cooney Ridge Fire Experiment: An early operation to relate pre-, active, and post-fire field and remotely sensed measurements

Treesearch

Andrew T. Hudak; Patrick H. Freeborn; Sarah A. Lewis; Sharon M. Hood; Helen Y. Smith; Colin C. Hardy; Robert J. Kremens; Bret W. Butler; Casey Teske; Robert G. Tissell; Lloyd P. Queen; Bryce L. Nordgren; Benjamin C. Bright; Penelope Morgan; Philip J. Riggan; Lee Macholz; Leigh B. Lentile; James P. Riddering; Edward E. Mathews

2018-01-01

The Cooney Ridge Fire Experiment conducted by fire scientists in 2003 was a burnout operation supported by a fire suppression crew on the active Cooney Ridge wildfire incident. The fire experiment included measurements of pre-fire fuels, active fire behavior, and immediate post-fire effects. Heat flux measurements collected at multiple scales with multiple ground and...

Environment, behavior and physiology: do birds use barometric pressure to predict storms?

PubMed

Breuner, Creagh W; Sprague, Rachel S; Patterson, Stephen H; Woods, H Arthur

2013-06-01

Severe storms can pose a grave challenge to the temperature and energy homeostasis of small endothermic vertebrates. Storms are accompanied by lower temperatures and wind, increasing metabolic expenditure, and can inhibit foraging, thereby limiting energy intake. To avoid these potential problems, most endotherms have mechanisms for offsetting the energetic risks posed by storms. One possibility is to use cues to predict oncoming storms and to alter physiology and behavior in ways that make survival more likely. Barometric pressure declines predictably before inclement weather, and several lines of evidence indicate that animals alter behavior based on changes in ambient pressure. Here we examined the effects of declining barometric pressure on physiology and behavior in the white-crowned sparrow, Zonotrichia leucophrys. Using field data from a long-term study, we first evaluated the relationship between barometric pressure, storms and stress physiology in free-living white-crowned sparrows. We then manipulated barometric pressure experimentally in the laboratory and determined how it affects activity, food intake, metabolic rates and stress physiology. The field data showed declining barometric pressure in the 12-24 h preceding snowstorms, but we found no relationship between barometric pressure and stress physiology. The laboratory study showed that declining barometric pressure stimulated food intake, but had no effect on metabolic rate or stress physiology. These data suggest that white-crowned sparrows can sense and respond to declining barometric pressure, and we propose that such an ability may be common in wild vertebrates, especially small ones for whom individual storms can be life-threatening events.

Fire behavior modeling-a decision tool

Treesearch

Jack Cohen; Bill Bradshaw

1986-01-01

The usefulness of an analytical model as a fire management decision tool is determined by the correspondence of its descriptive capability to the specific decision context. Fire managers must determine the usefulness of fire models as a decision tool when applied to varied situations. Because the wildland fire phenomenon is complex, analytical fire spread models will...

Domains of Risk in the Developmental Continuity of Fire Setting

ERIC Educational Resources Information Center

McCarty, Carolyn A.; McMahon, Robert J.

2005-01-01

Juvenile fire setting is a serious, dangerous, and costly behavior. The majority of research examining youth fire setting has been cross-sectional. We sought to examine early risk attributes that could differentiate fire setters from non-fire setters, in addition to examining their association with the developmental continuity of fire-setting…

Fire growth maps for the 1988 Greater Yellowstone Area Fires

Treesearch

Richard C. Rothermel; Roberta A Hartford; Carolyn H. Chase

1994-01-01

Daily fire growth maps display the growth of the 1988 fires in the Greater Yellowstone Area. Information and data sources included daily infrared photography flights, satellite imagery, ground and aerial reconnaissance, command center intelligence, and the personal recollections of fire behavior observers. Fire position was digitized from topographic maps using GRASS...

Little Bear Fire Summary Report

Treesearch

Sarah McCaffrey; Melanie Stidham; Hannah. Brenkert-Smith

2013-01-01

In June 2012, immediately after the Little Bear Fire burned outside Ruidoso, New Mexico, a team of researchers interviewed fire managers, local personnel, and residents to understand perceptions of the event itself, communication, evacuation, and pre-fire preparedness. The intensity of fire behavior and resulting loss of 242 homes made this a complex fire with a...

Fire interest and antisociality as risk factors in the severity and persistence of juvenile firesetting.

PubMed

MacKay, Sherri; Henderson, Joanna; Del Bove, Giannetta; Marton, Peter; Warling, Diane; Root, Carol

2006-09-01

In the DSM-IV-TR, firesetting is included as a criterion for the diagnoses of conduct disorder and pyromania. The link between firesetting and antisocial behavior is well established in the empirical literature. Although theoretical models of firesetting often include fire interest as a putative risk factor, there is little research on the role of fire interest in firesetting or on the construct of pyromania. The present study evaluated a sample of children and adolescents referred to an outpatient specialty program for juvenile firesetters with firesetting as the primary presenting problem. By assessing fire interest and antisocial behavior concurrently, the contribution of fire interest to firesetting after controlling for the role of conduct problems was evaluated. Results revealed that fire interest and antisocial behavior were significantly and positively correlated. Moreover, variations in fire interest added to the prediction of firesetting severity at assessment and firesetting recidivism at 18-month follow-up above and beyond what was predicted by antisociality alone. These findings have implications for an empirically derived taxonomy of pathological firesetting.

A clinical evaluation of comprehensive dental treatment for children under general anesthesia.

PubMed

Su, H L; Chen, P S

1992-12-01

The purpose of this study is to evaluate the comprehensive dental treatment for children under general anesthesia. From 1989 to 1991, 57 children with mean age of 3 years 2 months were treated, followed up with a minimal of 1 year. This procedure allows the dentition to be restored in one visit. Further care including preventive options and behavior shaping was provided on a 3-6 months recall schedule. The reasons for general anesthesia are that these children were either unable to accept treatment because of handicaps, extreme fear or young age. Their mean number of decayed tooth was 15 (Standard Deviation, SD = 5) and nearly three quarters of the children were under 6 years old. The most frequent treatment procedures were the extraction of teeth, composite resin restoration and Ni-Cr crown restoration. The Ni-Cr crown (1.7% failure rate) was more successful than the amalgam and composite resin restoration (9.7% failure rate). Pedo-strip crown had the highest failure rate (22%) for anterior teeth restoration. Nineteen children needed retreatment with conventional behavior guide. Six children had new caries and required further treatment. Thirty eight children returned for regular recall during the minimal 1 year follow-up period.

Fire and Smoke Model Evaluation Experiment (FASMEE): Modeling gaps and data needs

Treesearch

Yongqiang Liu; Adam Kochanski; Kirk Baker; Ruddy Mell; Rodman Linn; Ronan Paugam; Jan Mandel; Aime Fournier; Mary Ann Jenkins; Scott Goodrick; Gary Achtemeier; Andrew Hudak; Matthew Dickson; Brian Potter; Craig Clements; Shawn Urbanski; Roger Ottmar; Narasimhan Larkin; Timothy Brown; Nancy French; Susan Prichard; Adam Watts; Derek McNamara

2017-01-01

Fire and smoke models are numerical tools for simulating fire behavior, smoke dynamics, and air quality impacts of wildland fires. Fire models are developed based on the fundamental chemistry and physics of combustion and fire spread or statistical analysis of experimental data (Sullivan 2009). They provide information on fire spread and fuel consumption for safe and...

Response of Bighead Carp and Silver Carp to repeated water gun operation in an enclosed shallow pond

USGS Publications Warehouse

Romine, Jason G.; Jensen, Nathan; Parsley, Michael J.; Gaugush, Robert F.; Severson, Todd J.; Hatton, Tyson W.; Adams, Ryan F.; Gaikowski, Mark P.

2015-01-01

The Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix are nonnative species that pose a threat to Great Lakes ecosystems should they advance into those areas. Thus, technologies to impede Asian carp movement into the Great Lakes are needed; one potential technology is the seismic water gun. We evaluated the efficacy of a water gun array as a behavioral deterrent to the movement of acoustic-tagged Bighead Carp and Silver Carp in an experimental pond. Behavioral responses were evaluated by using four metrics: (1) fish distance from the water guns (D); (2) spatial area of the fish's utilization distribution (UD); (3) persistence velocity (Vp); and (4) number of times a fish transited the water gun array. For both species, average D increased by 10 m during the firing period relative to the pre-firing period. During the firing period, the spatial area of use within the pond decreased. Carp were located throughout the pond during the pre-firing period but were concentrated in the north end of the pond during the firing period, thus reducing their UDs by roughly 50%. Overall, Vp decreased during the firing period relative to the pre-firing period, as fish movement became more tortuous and confined, suggesting that the firing of the guns elicited a change in carp behavior. The water gun array was partially successful at impeding carp movement, but some fish did transit the array. Bighead Carp moved past the guns a total of 78 times during the pre-firing period and 15 times during the firing period; Silver Carp moved past the guns 96 times during the pre-firing period and 13 times during the firing period. Although the water guns did alter carp behavior, causing the fish to move away from the guns, this method was not 100% effective as a passage deterrent.

A tilting wind tunnel for fire behavior studies

Treesearch

David R. Weise

1994-01-01

The combined effects of wind velocity and slope on wildland fire behavior can be studied in the laboratory using a tilting wind tunnel. The tilting wind tunnel requires a commercially available fan to induce wind and can be positioned to simulate heading and backing fires spreading up and down slope. The tunnel is portable and can be disassembled for transport using a...

Photo guide for estimating fuel loading and fire behavior in mixed-oak forests of the Mid-Atlantic Region

Treesearch

Patrick H. Brose

2009-01-01

A field guide of 45 pairs of photographs depicting ericaceous shrub, leaf litter, and logging slash fuel types of eastern oak forests and observed fire behavior of these fuel types during prescribed burning. The guide contains instructions on how to use the photo guide to choose appropriate fuel models for prescribed fire planning.

A simplified test for adhesive behavior in wood sections exposed to fire

Treesearch

E. L. Schaffer

1968-01-01

A relatively simple test procedure was developed to evaluate the behavior of various adhesives near fire-exposed surfaces in laminated constructions. A number of sections cut from laminated blocks were exposed to fire on one surface. After this exposure, the sections were transversely cut, and the gluelines were examined for separation depth. In addition, the cool...

1st Fire Behavior and Fuels Conference: Fuels Management-How to Measure Success

Treesearch

Patricia L. Andrews

2006-01-01

The 1st Fire Behavior and Fuels Conference: Fuels Management -- How to Measure Success was held in Portland, Oregon, March 28-30, 2006. The International Association of Wildland Fire (IAWF) initiated a conference on this timely topic primarily in response to the needs of the U.S. National Interagency Fuels Coordinating Group (http://www.nifc.gov/).

Investigation of firebrand generation from an experimental fire: Development of a reliable data collection methodology

Treesearch

Jan C. Thomas; Eric V. Mueller; Simon Santamaria; Michael Gallagher; Mohamad El Houssami; Alexander Filkov; Kenneth Clark; Nicholas Skowronski; Rory M. Hadden; William Mell; Albert Simeoni

2017-01-01

An experimental approach has been developed to quantify the characteristics and flux of firebrands during a management-scale wildfire in a pine-dominated ecosystem. By characterizing the local fire behavior and measuring the temporal and spatial variation in firebrand collection, the flux of firebrands has been related to the fire behavior for the first time. This...

Photo Series for Estimating Post-Hurricane Residues and Fire Behavior in Southern Pine

Treesearch

Dale D. Wade; James K. Forbus; James M. Saveland

1993-01-01

Following Hurricane Hugo, fuels were sampled on nine 2-acre blocks which were then burned during the spring wildfire season. The study was superimposed on dormant-season fire-interval research plots established in 1958 on the Francis Marion National Forest near Charleston, SC. Photographs of preburn fuel loads, fire behavior, and postburn fuel loads were taken to...

Evaluating potential changes in fire risk from Eucalyptus plantings in the Southern United States

Treesearch

Scott L. Goodrick; John A. Stanturf

2012-01-01

Renewed interest in short-rotation woody crops for bioenergy and bioproducts has prompted a reevaluation of the Eucalyptus species for the southern United States. One question that arises about the potential effects of introducing a nonnative species is what effect will there be on fire behavior. Our approximate answer based on modeling fire behavior...

Landscape variation in tree regeneration and snag fall drive fuel loads in 24-year old post-fire lodgepole pine forests.

PubMed

Nelson, Kellen N; Turner, Monica G; Romme, William H; Tinker, Daniel B

2016-12-01

Escalating wildfire in subalpine forests with stand-replacing fire regimes is increasing the extent of early-seral forests throughout the western USA. Post-fire succession generates the fuel for future fires, but little is known about fuel loads and their variability in young post-fire stands. We sampled fuel profiles in 24-year-old post-fire lodgepole pine (Pinus contorta var. latifolia) stands (n = 82) that regenerated from the 1988 Yellowstone Fires to answer three questions. (1) How do canopy and surface fuel loads vary within and among young lodgepole pine stands? (2) How do canopy and surface fuels vary with pre- and post-fire lodgepole pine stand structure and environmental conditions? (3) How have surface fuels changed between eight and 24 years post-fire? Fuel complexes varied tremendously across the landscape despite having regenerated from the same fires. Available canopy fuel loads and canopy bulk density averaged 8.5 Mg/ha (range 0.0-46.6) and 0.24 kg/m 3 (range: 0.0-2.3), respectively, meeting or exceeding levels in mature lodgepole pine forests. Total surface-fuel loads averaged 123 Mg/ha (range: 43-207), and 88% was in the 1,000-h fuel class. Litter, 1-h, and 10-h surface fuel loads were lower than reported for mature lodgepole pine forests, and 1,000-h fuel loads were similar or greater. Among-plot variation was greater in canopy fuels than surface fuels, and within-plot variation was greater than among-plot variation for nearly all fuels. Post-fire lodgepole pine density was the strongest positive predictor of canopy and fine surface fuel loads. Pre-fire successional stage was the best predictor of 100-h and 1,000-h fuel loads in the post-fire stands and strongly influenced the size and proportion of sound logs (greater when late successional stands had burned) and rotten logs (greater when early successional stands had burned). Our data suggest that 76% of the young post-fire lodgepole pine forests have 1,000-h fuel loads that exceed levels associated with high-severity surface fire potential, and 63% exceed levels associated with active crown fire potential. Fire rotations in Yellowstone National Park are predicted to shorten to a few decades and this prediction cannot be ruled out by a lack of fuels to carry repeated fires. © 2016 by the Ecological Society of America.

Smoke Alarms for People Who Are Deaf or Hard-of-Hearing

MedlinePlus

... motels Expand sub-navigation Hotel fire safety tips Marijuana grow & extraction facilities Nightclubs and other assembly occupancies ... Fire behavior research Fire loss and injury research Benefits of home fire sprinklers Expand sub-navigation Environmental ...

Simulating spatial and temporally related fire weather

Treesearch

Isaac C. Grenfell; Mark Finney; Matt Jolly

2010-01-01

Use of fire behavior models has assumed an increasingly important role for managers of wildfire incidents to make strategic decisions. For fire risk assessments and danger rating at very large spatial scales, these models depend on fire weather variables or fire danger indices. Here, we describe a method to simulate fire weather at a national scale that captures the...

Decision making under uncertainty: Recommendations for the Wildland Fire Decision Support System (WFDSS)

Treesearch

Matthew P. Thompson

2015-01-01

The management of wildfire is a dynamic, complex, and fundamentally uncertain enterprise. Fire managers face uncertainties regarding fire weather and subsequent influence on fire behavior, the effects of fire on socioeconomic and ecological resources, and the efficacy of alternative suppression actions on fire outcomes. In these types of difficult decision environments...

Atmospheric turbulence observations in the vicinity of surface fires in forested environments

Treesearch

Warren E. Heilman; Xindi Bian; Kenneth L. Clark; Nicholas S. Skowronski; John L. Hom; Michael R. Gallagher

2017-01-01

Ambient and fire-induced atmospheric turbulence in the vicinity of wildland fires can affect the behavior of those fires and the dispersion of smoke. The presence of forest overstory vegetation can further complicate the evolution of local turbulence regimes and their interaction with spreading fires and smoke plumes. Previous observational studies of wildland fire...

Decision modeling for analyzing fire action outcomes

Treesearch

Donald MacGregor; Armando Gonzalez-Caban

2008-01-01

A methodology for incident decomposition and reconstruction is developed based on the concept of an "event-frame model." The event-frame model characterizes a fire incident in terms of (a) environmental events that pertain to the fire and the fire context (e.g., fire behavior, weather, fuels) and (b) management events that represent responses to the fire...

Shift in fire-ecosystems and weather changes

Treesearch

Bongani Finiza

2013-01-01

During recent decades too much focus fell on fire suppression and fire engineering methods. Little attention has been given to understanding the shift in the changing fire weather resulting from the global change in weather patterns. Weather change have gradually changed the way vegetation cover respond to fire occurrence and brought about changes in fire behavior and...

Uniform versus Asymmetric Shading Mediates Crown Recession in Conifers

PubMed Central

Schoonmaker, Amanda L.; Lieffers, Victor J.; Landhäusser, Simon M.

2014-01-01

In this study we explore the impact of asymmetrical vs. uniform crown shading on the mortality and growth of upper and lower branches within tree crowns, for two conifer species: shade intolerant lodgepole pine (Pinus contorta) and shade tolerant white spruce (Picea glauca). We also explore xylem hydraulics, foliar nutrition, and carbohydrate status as drivers for growth and expansion of the lower and upper branches in various types of shading. This study was conducted over a two-year period across 10 regenerating forest sites dominated by lodgepole pine and white spruce, in the lower foothills of Alberta, Canada. Trees were assigned to one of four shading treatments: (1), complete uniform shading of the entire tree, (2) light asymmetric shading where the lower 1/4–1/3 of the tree crown was shaded, (3) heavy asymmetric shading as in (2) except with greater light reduction and (4) control in which no artificial shading occurred and most of the entire crown was exposed to full light. Asymmetrical shading of only the lower crown had a larger negative impact on the bud expansion and growth than did uniform shading, and the effect was stronger in pine relative to spruce. In addition, lower branches in pine also had lower carbon reserves, and reduced xylem-area specific conductivity compared to spruce. For both species, but particularly the pine, the needles of lower branches tended to store less C than upper branches in the asymmetric shade, which could suggest a movement of reserves away from the lower branches. The implications of these findings correspond with the inherent shade tolerance and self-pruning behavior of these conifers and supports a carbon based mechanism for branch mortality – mediated by an asymmetry in light exposure of the crown. PMID:25136823

Uniform versus asymmetric shading mediates crown recession in conifers.

PubMed

Schoonmaker, Amanda L; Lieffers, Victor J; Landhäusser, Simon M

2014-01-01

In this study we explore the impact of asymmetrical vs. uniform crown shading on the mortality and growth of upper and lower branches within tree crowns, for two conifer species: shade intolerant lodgepole pine (Pinus contorta) and shade tolerant white spruce (Picea glauca). We also explore xylem hydraulics, foliar nutrition, and carbohydrate status as drivers for growth and expansion of the lower and upper branches in various types of shading. This study was conducted over a two-year period across 10 regenerating forest sites dominated by lodgepole pine and white spruce, in the lower foothills of Alberta, Canada. Trees were assigned to one of four shading treatments: (1), complete uniform shading of the entire tree, (2) light asymmetric shading where the lower 1/4-1/3 of the tree crown was shaded, (3) heavy asymmetric shading as in (2) except with greater light reduction and (4) control in which no artificial shading occurred and most of the entire crown was exposed to full light. Asymmetrical shading of only the lower crown had a larger negative impact on the bud expansion and growth than did uniform shading, and the effect was stronger in pine relative to spruce. In addition, lower branches in pine also had lower carbon reserves, and reduced xylem-area specific conductivity compared to spruce. For both species, but particularly the pine, the needles of lower branches tended to store less C than upper branches in the asymmetric shade, which could suggest a movement of reserves away from the lower branches. The implications of these findings correspond with the inherent shade tolerance and self-pruning behavior of these conifers and supports a carbon based mechanism for branch mortality--mediated by an asymmetry in light exposure of the crown.

The fire environment--innovations, management, and policy; conference proceedings

Treesearch

Bret W. Butler; Wayne Cook

2007-01-01

The International Association of Wildland Fire sponsored the second Fire Behavior and Fuels conference in Destin, Florida. The conference theme was "Fire Environment--Innovations, Management, and Policy." Over 450 attendees participated in presentations on the latest innovations in wildland fire management, examples of successful and maybe not so successful...

Impacts of frequent, acute pulses of corticosterone on condition and behavior of Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii).

PubMed

Busch, D Shallin; Sperry, Todd S; Peterson, Eric; Do, Cam-Tu; Wingfield, John C; Boyd, Ellen H

2008-09-15

Little is known about how frequent, acute stressors affect wild animals. We present two experiments conducted on captive, Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii) that explore how frequent, acute doses of corticosterone (CORT) affect condition and behavior. CORT was administered either once or three times a day to birds in pre-breeding, early-breeding, or late-breeding life-history stages. Two additional groups were included to control for the CORT delivery vehicle, DMSO, and the treatment process. Our results indicate that CORT treatment decreases condition, but that its effects are dependent on frequency and life stage. Specifically, CORT-treated birds delayed the onset of molt and had reduced body mass, flight muscle, and food consumption. CORT treatment did not affect fat stores, bile retention in the gallbladder, or the expression of migratory restlessness behavior. These results increase our understanding of the effects of frequent, acute stressors and the development of chronic stress states.

Resource allocation for wildland fire suppression planning using a stochastic program

Treesearch

Alex Taylor Masarie

2011-01-01

Resource allocation for wildland fire suppression problems, referred to here as Fire-S problems, have been studied for over a century. Not only have the many variants of the base Fire-S problem made it such a durable one to study, but advances in suppression technology and our ever-expanding knowledge of and experience with wildland fire behavior have required almost...

Effectiveness of Fire and Fire Surrogate Treatments For Controlling Wildfire Behavior in Piedmont Forests: A Simulation Study

Treesearch

Helen H. Mohr; Thomas A. Waldrop; Sandra Rideout; Ross J. Phillips; Charles T. Flint

2004-01-01

The need for fuel reduction has increased in United States forests due to decades of fire exclusion. Excessive fuel buildup has led to uncharacteristically severe fires in areas with historically short-interval, low-to-moderate-intensity fire regimes. The National Fire and Fire Surrogate (NFFS) Study compared the impacts of three fuel-reduction treatments on numerous...

Ecological effects of the Hayman Fire - Part 1: Historical (pre-1860) and current (1860-2002) fire regimes

Treesearch

William H. Romme; Thomas T. Veblen; Merrill R. Kaufmann; Rosemary Sherriff; Claudia M. Regan

2003-01-01

To address historical and current fire regimes in the Hayman landscape, we first present the concepts of “historical range of variability” and ”fire regime” to provide the necessary conceptual tools for evaluating fire occurrence, fire behavior, and fire effects. Next we summarize historical (pre-1860) fire frequency and fire effects for the major forest types of the...

The influence of an incomplete fuels treatment on fire behavior and effects in the 2007 Tin Cup Fire, Bitterroot National Forest, Montana

Treesearch

Michael Harrington; Erin Noonan-Wright

2010-01-01

Extensive forested areas have received fuels treatments in recent decades and significant funding is available for additional treatments in an attempt to mitigate undesirable high wildfire intensities and impacts. Fuel treatment successes and failures in moderating fire behavior and effects can be found in quantified and anecdotal reports. Questions remain about the...

Predicting the effect of climate change on wildfire behavior and initial attack success

Treesearch

Jeremy S. Fried; J. Keith Gilless; William J. Riley; Tadashi J. Moody; Clara Simon de Blas; Katharine Hayhoe; Max Mortiz; Scott Stephens; Margaret Torn

2008-01-01

This study focused on how climate change-induced effects on weather will translate into changes in wildland fire severity and outcomes in California, particularly on the effectiveness of initial attack at limiting the number of fires that escape initial attack. The results indicate that subtle shifts in fire behavior of the sort that might be induced by the climate...

Use of models to study forest fire behavior

Treesearch

Wallace L. Fons

1961-01-01

The U.S. Forest Service has started a laboratory study with the ultimate objective of determining model laws for fire behavior. The study includes an examination of the effect of such variables as species of wood, density of wood, moisture content, size of fuel particle, spacing, dimensions of fuel bed, wind, and slope on the rate of spread of fire and the partition of...

Wild Fire Computer Model Helps Firefighters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canfield, Jesse

2012-09-04

A high-tech computer model called HIGRAD/FIRETEC, the cornerstone of a collaborative effort between U.S. Forest Service Rocky Mountain Research Station and Los Alamos National Laboratory, provides insights that are essential for front-line fire fighters. The science team is looking into levels of bark beetle-induced conditions that lead to drastic changes in fire behavior and how variable or erratic the behavior is likely to be.

Wild Fire Computer Model Helps Firefighters

ScienceCinema

Canfield, Jesse

2018-02-14

A high-tech computer model called HIGRAD/FIRETEC, the cornerstone of a collaborative effort between U.S. Forest Service Rocky Mountain Research Station and Los Alamos National Laboratory, provides insights that are essential for front-line fire fighters. The science team is looking into levels of bark beetle-induced conditions that lead to drastic changes in fire behavior and how variable or erratic the behavior is likely to be.

Strategic Placement of Treatments (SPOTS): Maximizing the Effectiveness of Fuel and Vegetation Treatments on Problem Fire Behavior and Effects

Treesearch

Diane M. Gercke; Susan A. Stewart

2006-01-01

In 2005, eight U.S. Forest Service and Bureau of Land Management interdisciplinary teams participated in a test of strategic placement of treatments (SPOTS) techniques to maximize the effectiveness of fuel treatments in reducing problem fire behavior, adverse fire effects, and suppression costs. This interagency approach to standardizing the assessment of risks and...

The effects of raking on sugar pine mortality following prescribed fire in Sequoia and Kings Canyon National Parks, California, USA

USGS Publications Warehouse

Nesmith, Jonathan C. B.; O'Hara, Kevin L.; van Mantgem, Phillip J.; de Valpine, Perry

2010-01-01

Prescribed fire is an important tool for fuel reduction, the control of competing vegetation, and forest restoration. The accumulated fuels associated with historical fire exclusion can cause undesirably high tree mortality rates following prescribed fires and wildfires. This is especially true for sugar pine (Pinus lambertiana Douglas), which is already negatively affected by the introduced pathogen white pine blister rust (Cronartium ribicola J.C. Fisch. ex Rabenh). We tested the efficacy of raking away fuels around the base of sugar pine to reduce mortality following prescribed fire in Sequoia and Kings Canyon national parks, California, USA. This study was conducted in three prescribed fires and included 457 trees, half of which had the fuels around their bases raked away to mineral soil to 0.5 m away from the stem. Fire effects were assessed and tree mortality was recorded for three years after prescribed fires. Overall, raking had no detectable effect on mortality: raked trees averaged 30% mortality compared to 36% for unraked trees. There was a significant effect, however, between the interaction of raking and average pre-treatment forest floor fuel depth: the predicted probability of survival of a 50 cm dbh tree was 0.94 vs. 0.96 when average pre-treatment fuel depth was 0 cm for a raked and unraked tree, respectively. When average pre-treatment forest floor fuel depth was 30 cm, the predicted probability of survival for a raked 50 cm dbh tree was 0.60 compared to only 0.07 for an unraked tree. Raking did not affect mortality when fire intensity, measured as percent crown volume scorched, was very low (0% scorch) or very high (>80% scorch), but the raking treatment significantly increased the proportion of trees that survived by 9.6% for trees that burned under moderate fire intensity (1% to 80% scorch). Raking significantly reduced the likelihood of bole charring and bark beetle activity three years post fire. Fuel depth and anticipated fire intensity need to be accounted for to maximize the effectiveness of the treatments. Raking is an important management option to reduce tree mortality from prescribed fire, but is most effective under specific fuel and burning conditions.

ECKG Kladno project: First IPP in the Czech Republic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rode, J.R.; Tichy, O.J.

1999-07-01

The Energy Center Kladno project is the first independent power producer (IPP) project to be financed in the Czech Republic, one of Europe's most rapidly evolving markets. The total financing is $401 million and is structured in three currencies; Czech crowns, German marks, and US dollars. This paper will focus on: Enhanced technology to meet energy demands; Execution to meet the ambitious; and Overall project status. The coal and gas fired plant will produce a total of 343 MW to provide electricity and heat to the town of Kladno, west of Prague. The new plant will be located within themore » existing ECK facility and the project encompasses demolition, upgrading, and rebuilding. The base load will be from two coal-fired 135 MW circulating fluidized bed (CFB) boilers and peaking capacity from the gas-fired combustion (66 MW) turbine. The CFB's will fire a range of low sulfur brown coal supplied from the local mining company Ceskomoravske Doly (CMD). The new CFB's were designed to meet the overall steam demands specified by ECKG. The CFB's design features include in-furnace heat transfer surface and a split backpass that utilizes a biasing damper to allow for control of both the superheat and reheat steam temperatures. The various CFB auxiliary systems will be discussed in the paper as well as the flue gas particulate collection equipment.« less

Predicting wildfire behavior in black spruce forests in Alaska.

Treesearch

Rodney A. Norum

1982-01-01

The current fire behavior system, when properly adjusted, accurately predicts forward rate of spread and flame length of wildfires in black spruce (Picea mariana (Mill.) B.S.P.) forests in Alaska. After fire behavior was observed and quantified, adjustment factors were calculated and assigned to the selected fuel models to correct the outputs to...

Landslides, forest fires, and earthquakes: examples of self-organized critical behavior

NASA Astrophysics Data System (ADS)

Turcotte, Donald L.; Malamud, Bruce D.

2004-09-01

Per Bak conceived self-organized criticality as an explanation for the behavior of the sandpile model. Subsequently, many cellular automata models were found to exhibit similar behavior. Two examples are the forest-fire and slider-block models. Each of these models can be associated with a serious natural hazard: the sandpile model with landslides, the forest-fire model with actual forest fires, and the slider-block model with earthquakes. We examine the noncumulative frequency-area statistics for each natural hazard, and show that each has a robust power-law (fractal) distribution. We propose an inverse-cascade model as a general explanation for the power-law frequency-area statistics of the three cellular-automata models and their ‘associated’ natural hazards.

Vertical stratification of the nutritional value of fruit: macronutrients and condensed tannins.

PubMed

Houle, Alain; Conklin-Brittain, Nancy L; Wrangham, Richard W

2014-12-01

Competing successfully for the best feeding sites is an important behavioral strategy but little is known about how feeding sites vary nutritionally within a fruit tree. To answer this question we tested how the nutritional value of a fruit is influenced by its ripeness and its height within the tree crown. A complementary objective was to assess the nutritional value of the midripe fruit, a food item rarely mentioned in the literature despite being exploited on a daily basis by many frugivores. We measured how the dry weight of pulp, water content, and concentration of macronutrients and condensed tannins varied within the tree crowns of 15 fruit species. Collections occurred early in the fruiting cycle, so as to assess the amount of food in the tree before its exploitation by primates. We found that (1) the upper crown produced fruit densities 4.2 times higher, and a fruit crop 4.8 times larger, than the lower crown of the same tree; (2) considering only midripe and ripe stages, upper-crown fruits contained 28.6% more dry pulp, 21.1% more water, and 13.5% more sugars per dry matter than lower-crown fruits of the same tree; (3) midripe fruits contained 80% of the concentrations of sugars of ripe fruits, making them a sweeter food item than one would expect from the intermediate color of their epidermis; (4) cellulose, hemicellulose, proteins, and ash proportionally decreased in concentration while dry pulp and sugars increased during ripening; and (5) ripe fruits were usually rare in the tree (<0.5% of all fruit available) compared to midripe fruits (3-8%). Overall, upper-crown feeding sites produced a higher density and quality of food than lower-crown sites of the same tree. Our data therefore provide a clear nutritional explanation for why tree-feeding frugivores compete for the highest feeding sites. © 2014 Wiley Periodicals, Inc.

Fire behavior of transformer dielectric insulating fluids

DOT National Transportation Integrated Search

1980-01-31

This report presents results for the fire behavior of pure and askarel-contaminated fluids which are candidates for use as railroad transformer dielectric insulating fluids. In the study a hydrocarbon and a dimethyl-siloxane fluid were examined. The ...

An Examination of Extreme Fire Behavior and its Impact on Smoke Injection Altitude using Remote Sensing and Meteorological Data

NASA Astrophysics Data System (ADS)

Peterson, D. A.; Hyer, E. J.; Campbell, J. R.; Fromm, M. D.; Hair, J. W.; Butler, C. F.; Fenn, M. A.

2014-12-01

A variety of regional smoke forecasting applications are currently available to identify air quality, visibility, and societal impacts during large fire events. However, these systems typically assume persistent fire activity, and therefore can have large errors before, during, and after short-term periods of extreme fire behavior. This study employs a wide variety of ground, airborne, and satellite observations, including data collected during a major NASA airborne and field campaign, to examine the conditions required for both extreme spread and pyrocumulonimbus (pyroCb) development. Results highlight the importance of upper-level and nocturnal meteorology, as well as the limitations of traditional fire weather indices. Increasing values of fire radiative power (FRP) at the pixel and sub-pixel level are shown to systematically correspond to higher altitude smoke plumes, and an increased probability of injection above the boundary layer. Lidar data collected during the 2013 Rim Fire, one of the most severe fire events in California's history, show that high FRP observed during extreme spread can facilitate long-distance smoke transport, but fails to loft smoke to the altitude of a large pyroCb. The most extreme fire spread was also observed on days without pyroCb activity or significant regional convection. By incorporating additional fire events across North America, conflicting hypotheses surrounding the primary source of moisture during pyroCb development are examined. The majority of large pyroCbs, and therefore the highest direct injection altitude of smoke particles, is shown to occur with conditions very similar to those that produce dry thunderstorms. The current suite of automated forecasting applications predict only general trends in fire behavior, and specifically do not predict (1) extreme fire spread events and (2) injection of smoke to high altitudes. While (1) and (2) are related, results show that they are not predicted by the same set of conditions and variables. The combination of meteorology from numerical forecast models and satellite observations exhibits great potential for improving regional forecasts of fire behavior and smoke production in automated systems, especially in remote areas where detailed observations are unavailable

Application of Argonne's Glass Furnace Model to longhorn glass corporation oxy-fuel furnace for the production of amber glass.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golchert, B.; Shell, J.; Jones, S.

2006-09-06

The objective of this project is to apply the Argonne National Laboratory's Glass Furnace Model (GFM) to the Longhorn oxy-fuel furnace to improve energy efficiency and to investigate the transport of gases released from the batch/melt into the exhaust. The model will make preliminary estimates of the local concentrations of water, carbon dioxide, elemental oxygen, and other subspecies in the entire combustion space as well as the concentration of these species in the furnace exhaust gas. This information, along with the computed temperature distribution in the combustion space may give indications on possible locations of crown corrosion. An investigation intomore » the optimization of the furnace will be performed by varying several key parameters such as the burner firing pattern, exhaust number/size, and the boost usage (amount and distribution). Results from these parametric studies will be analyzed to determine more efficient methods of operating the furnace that reduce crown corrosion. Finally, computed results from the GFM will be qualitatively correlated to measured values, thus augmenting the validation of the GFM.« less

Variability of fire behavior, fire effects, and emissions in Scotch pine forests of central Siberia

Treesearch

D. J. McRae; Susan Conard; G. A. Ivanova; A. I. Sukhinin; Steve Baker; Y. N. Samsonov; T. W. Blake; V. A. Ivanov; A. V. Ivanov; T. V. Churkina; WeiMin Hao; K. P. Koutzenogij; Nataly Kovaleva

2006-01-01

As part of the Russian FIRE BEAR (Fire Effects in the Boreal Eurasia Region) Project, replicated 4-ha experimental fires were conducted on a dry Scotch pine (Pinus sylvestris)/lichen (Cladonia sp.)/feathermoss (Pleurozeum schreberi) forest site in central Siberia. Observations from the initial seven surface fires (2000-2001) ignited under a range of burning...

Effectiveness of Prescribed Fire as a Fuel Treatment in Californian Coniferous Forests

Treesearch

Nicole M. Vaillant; JoAnn Fites-Kaufman; Scott L. Stephens

2006-01-01

Effective fire suppression for the past century has altered forest structure and increased fuel loads. Prescribed fire as a fuels treatment can reduce wildfire size and severity. This study investigates how prescribed fire affects fuel loads, forest structure, potential fire behavior, and modeled tree mortality at 80th, 90th, and 97.5th percentile fire weather...

Continental-scale simulation of burn probabilities, flame lengths, and fire size distribution for the United States

Treesearch

Mark A. Finney; Charles W. McHugh; Isaac Grenfell; Karin L. Riley

2010-01-01

Components of a quantitative risk assessment were produced by simulation of burn probabilities and fire behavior variation for 134 fire planning units (FPUs) across the continental U.S. The system uses fire growth simulation of ignitions modeled from relationships between large fire occurrence and the fire danger index Energy Release Component (ERC). Simulations of 10,...

Progression and Behavior of the Canoe Fire in Coast Redwood

Treesearch

Hugh Scanlon

2007-01-01

Lightning caused fires occur in coast redwood forests, but large fires have been rare since the 1930s. Coast redwood (Sequoia sempervirens) is considered fire resistant. In 2003, the Canoe Fire, a lightning fire started in an old-growth redwood stand in Humboldt Redwoods State Park, burned 5,554 hectares (13,774 acres) before it was contained. Fuel...

Wilderness fire science: A state of knowledge review

Treesearch

James K. Agee

2000-01-01

Wilderness fire science has progressed since the last major review of the topic, but it was significantly affected by the large fire events of 1988. Strides have been made in both fire behavior and fire effects, and in the issues of scaling, yet much of the progress has not been specifically tied to wilderness areas or funding. Although the management of fire in...

Space station internal environmental and safety concerns

NASA Technical Reports Server (NTRS)

Cole, Matthew B.

1987-01-01

Space station environmental and safety concerns, especially those involving fires, are discussed. Several types of space station modules and the particular hazards associated with each are briefly surveyed. A brief history of fire detection and suppression aboard spacecraft is given. Microgravity fire behavior, spacecraft fire detector systems, space station fire suppression equipment and procedures, and fire safety in hyperbaric chambers are discussed.

Value and challenges of conducting rapid response research on wildland fires

Treesearch

L. Lentile; P. Morgan; C. Hardy; A. Hudak; R. Means; R. Ottmar; P. Robichaud; E. Kennedy Sutherland; J. Szymoniak; F. Way; J. Fites-Kaufman; S. Lewis; E. Mathews; H. Shovik; K. Ryan

2007-01-01

Rapid Response Research is conducted during and immediately after wildland fires, in coordination with fire management teams, in order to collect information that can best be garnered in situ and in real-time. This information often includes fire behavior and fire effects data, which can be used to generate practical tools such as predictive fire models for managers....

BehavePlus fire modeling system, version 4.0: User's Guide

Treesearch

Patricia L. Andrews; Collin D. Bevins; Robert C. Seli

2005-01-01

The BehavePlus fire modeling system is a program for personal computers that is a collection of mathematical models that describe fire and the fire environment. It is a flexible system that produces tables, graphs, and simple diagrams. It can be used for a multitude of fire management applications including projecting the behavior of an ongoing fire, planning...

Social compatibility in a newly formed all-male group of white crowned mangabeys (Cercocebus atys lunulatus).

PubMed

Fàbregas, María; Guillén-Salazar, Federico

2007-01-01

Surplus males in primate captive populations are a common problem for zoos. Some captive breeding programs promote all-male groups as an adequate option to house surplus males, but there have been few attempts to assess the feasibility of this management technique across primate species. The present study provides preliminary data regarding social compatibility within a newly formed all-male group of four white crowned mangabeys (Cercocebus atys lunulatus). The study was conducted at the Valencia Zoo (Spain), where data on social behavior were collected over 6 months using continuous focal animal sampling for a total of 87 hr of observation. Results show that low intensity aggressive behaviors (facial threats) were expressed at high rates, whereas physical aggression (fights) rarely occurred. Aggression was more frequent among individuals belonging to the same age-gender class. Regarding affiliative behaviors, every individual actively sought proximity to all other group members through positive approaches, and although not all males carried out social grooming, every male was groomed by at least one group member. Our results suggest that the group was compatible socially because social relationships among the individuals were not neutral, and physical aggression occurred at low rates. The present study provides preliminary data supporting the feasibility of all-male groups as a management option for surplus males in captive populations of white crowned mangabeys. Nevertheless, further studies are needed to be able to generalize both within and across species. Zoo Biol 0:1-7, 2007. (c) 2006 Wiley-Liss, Inc.

Thermocouple Probe Orientation Affects Prescribed Fire Behavior Estimation.

PubMed

Coates, T Adam; Chow, Alex T; Hagan, Donald L; Waldrop, Thomas A; Wang, G Geoff; Bridges, William C; Rogers, Mary-Frances; Dozier, James H

2018-01-01

Understanding the relationship between fire intensity and fuel mass is essential information for scientists and forest managers seeking to manage forests using prescribed fires. Peak burning temperature, duration of heating, and area under the temperature profile are fire behavior metrics obtained from thermocouple-datalogger assemblies used to characterize prescribed burns. Despite their recurrent usage in prescribed burn studies, there is no simple protocol established to guide the orientation of thermocouple installation. Our results from dormant and growing season burns in coastal longleaf pine ( Mill.) forests in South Carolina suggest that thermocouples located horizontally at the litter-soil interface record significantly higher estimates of peak burning temperature, duration of heating, and area under the temperature profile than thermocouples extending 28 cm vertically above the litter-soil interface ( < 0.01). Surprisingly, vertical and horizontal estimates of these measures did not show strong correlation with one another ( ≤ 0.14). The horizontal duration of heating values were greater in growing season burns than in dormant season burns ( < 0.01), but the vertical values did not indicate this difference ( = 0.52). Field measures of fuel mass and depth before and after fire showed promise as significant predictive variables ( ≤ 0.05) for the fire behavior metrics. However, all correlation coefficients were less than or equal to = 0.41. Given these findings, we encourage scientists, researchers, and managers to carefully consider thermocouple orientation when investigating fire behavior metrics, as orientation may affect estimates of fire intensity and the distinction of fire treatment effects, particularly in forests with litter-dominated surface fuels. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Previous fires moderate burn severity of subsequent wildland fires in two large western US wilderness areas

Treesearch

Sean A. Parks; Carol Miller; Cara R. Nelson; Zachary A. Holden

2014-01-01

Wildland fire is an important natural process in many ecosystems. However, fire exclusion has reduced frequency of fire and area burned in many dry forest types, which may affect vegetation structure and composition, and potential fire behavior. In forests of the western U.S., these effects pose a challenge for fire and land managers who seek to restore the ecological...

Short- and long-term effects on fuels, forest structure, and wildfire potential from prescribed fire and resource benefit fire in southwestern forests, USA

Treesearch

Molly E. Hunter; Jose M. Iniguez; Leigh B. Lentile

2011-01-01

Prescribed and resource benefit fires are used to manage fuels in fire-prone landscapes in the Southwest. These practices, however, typically occur under different conditions, potentially leading to differences in fire behavior and effects. The objectives of this study were to investigate the effects of recent prescribed fires, resource benefit fires, and repeated...

Interactions among livestock grazing, vegetation type, and fire behavior in the Murphy Wildland Fire Complex in Idaho and Nevada, July 2007

USGS Publications Warehouse

Launchbaugh, Karen; Brammer, Bob; Brooks, Matthew L.; Bunting, Stephen C.; Clark, Patrick; Davison, Jay; Fleming, Mark; Kay, Ron; Pellant, Mike; Pyke, David A.

2008-01-01

A series of wildland fires were ignited by lightning in sagebrush and grassland communities near the Idaho-Nevada border southwest of Twin Falls, Idaho in July 2007. The fires burned for over two weeks and encompassed more than 650,000 acres. A team of scientists, habitat specialists, and land managers was called together by Tom Dyer, Idaho BLM State Director, to examine initial information from the Murphy Wildland Fire Complex in relation to plant communities and patterns of livestock grazing. Three approaches were used to examine this topic: (1) identify potential for livestock grazing to modify fuel loads and affect fire behavior using fire models applied to various vegetation types, fuel loads, and fire conditions; (2) compare levels of fuel consumed within and among major vegetation types; and (3) examine several observed lines of difference and discontinuity in fuel consumed to determine what factors created these contrasts. The team found that much of the Murphy Wildland Fire Complex burned under extreme fuel and weather conditions that likely overshadowed livestock grazing as a factor influencing fire extent and fuel consumption in many areas where these fires burned. Differences and abrupt contrast lines in the level of fuels consumed were affected mostly by the plant communities that existed on a site before fire. A few abrupt contrasts in burn severity coincided with apparent differences in grazing patterns of livestock, observed as fence-line contrasts. Fire modeling revealed that grazing in grassland vegetation can reduce surface rate of spread and fire-line intensity to a greater extent than in shrubland types. Under extreme fire conditions (low fuel moisture, high temperatures, and gusty winds), grazing applied at moderate utilization levels has limited or negligible effects on fire behavior. However, when weather and fuel-moisture conditions are less extreme, grazing may reduce the rate of spread and intensity of fires allowing for patchy burns with low levels of fuel consumption. The team suggested that targeted grazing to accomplish fuel objectives holds promise but requires detailed planning that includes clearly defined goals for fuel modification and appropriate monitoring to assess effectiveness. It was recommended that a pilot plan be devised to strategically place grazed blocks across a landscape to create fuel-reduction bands capable of influencing fire behavior. Also suggested was the development of a general technical report that highlights information and examples of how livestock grazing influences fire extent, severity, and intensity. Finally, the team encouraged continued research and monitoring of the effects of the Murphy Wildland Fire Complex. Much more can be learned from the effects of this extensive fire complex that may offer insight for future management decisions.

Post-fire vegetation and fuel development influences fire severity patterns in reburns.

PubMed

Coppoletta, Michelle; Merriam, Kyle E; Collins, Brandon M

2016-04-01

In areas where fire regimes and forest structure have been dramatically altered, there is increasing concern that contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire. Our study utilized an extensive set of field plots established following four fires that occurred between 2000 and 2010 in the northern Sierra Nevada, California, USA that were subsequently reburned in 2012. The information obtained from these field plots allowed for a unique set of analyses investigating the effect of vegetation, fuels, topography, fire weather, and forest management on reburn severity. We also examined the influence of initial fire severity and time since initial fire on influential predictors of reburn severity. Our results suggest that high- to moderate-severity fire in the initial fires led to an increase in standing snags and shrub vegetation, which in combination with severe fire weather promoted high-severity fire effects in the subsequent reburn. Although fire behavior is largely driven by weather, our study demonstrates that post-fire vegetation composition and structure are also important drivers of reburn severity. In the face of changing climatic regimes and increases in extreme fire weather, these results may provide managers with options to create more fire-resilient ecosystems. In areas where frequent high-severity fire is undesirable, management activities such as thinning, prescribed fire, or managed wildland fire can be used to moderate fire behavior not only prior to initial fires, but also before subsequent reburns.

Fire safety

Treesearch

Robert H. White; Mark A. Dietenberger

1999-01-01

Fire safety is an important concern in all types of construction. The high level of national concern for fire safety is reflected in limitations and design requirements in building codes. These code requirements are discussed in the context of fire safety design and evaluation in the initial section of this chapter. Since basic data on fire behavior of wood products...

Linking complex forest fuel structure and fire behavior at fine scales

Treesearch

EL Loudermilk; Joseph O' Brien; RJ Mitchell; JK Hiers; WP Cropper; S Grunwald; J Grego; J Fernandez

2012-01-01

Improved fire management of savannas and open woodlands requires better understanding of the fundamental connection between fuel heterogeneity, variation in fire behaviour and the influence of fire variation on vegetation feedbacks. In this study, we introduce a novel approach to predicting fire behaviour at the submetre scale, including measurements of forest...