Um die anderen Arten von Veröffentlichungen zu diesem Thema anzuzeigen, folgen Sie diesem Link: Effect of fire.
Zeitschriftenartikel zum Thema „Effect of fire“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit Top-50 Zeitschriftenartikel für die Forschung zum Thema "Effect of fire" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Sehen Sie die Zeitschriftenartikel für verschiedene Spezialgebieten durch und erstellen Sie Ihre Bibliographie auf korrekte Weise.
1
Mathieu, Renaud, Russell Main, David P. Roy, Laven Naidoo und Hannah Yang. „The Effect of Surface Fire in Savannah Systems in the Kruger National Park (KNP), South Africa, on the Backscatter of C-Band Sentinel-1 Images“. Fire 2, Nr. 3 (27.06.2019): 37. http://dx.doi.org/10.3390/fire2030037.
Der volle Inhalt der QuelleAnnotation:
Savannahs are mixed woody-grass communities where low-intensity surface fires are common, affecting mostly the grass layer and rarely damaging trees. We investigated the effect of surface fires in a savannah system in the Kruger National Park, South Africa, on the backscatter of synthetic aperture radar (SAR) C-band Sentinel-1A images. Pre-fire and post-fire dual polarized (VH, VV) C-band backscatter values were examined for 30 burn events. For all events, a systematic backscatter decrease from pre-fire to post-fire conditions was observed, with mean backscatter decreases of 1.61 dB and 0.99 dB for VH and VV, respectively. A total of 90% and 75% of the burn events showed a decrease in VH and VV backscatter greater than 0.43 dB, the overall absolute radiometric of Sentinel-1A products. The VH data were, overall, 1.7 times more sensitive to surface fire effects than the VV data. C-band data are likely sensitive to a reduction in grass biomass typical of surface fires, as well as in grass/soil moisture levels. Early season fires had higher backscatter decreases due to greater early season moisture conditions. For region with more than 30% woody cover, the effect of fire on the C-band backscatter was reduced. Denser woody communities tend to produce lower grass fuel load and less intense surface fires, and limit the penetration of C-band microwaves to the ground where most savannah fires and associated effects occur. This research provides evidence that C-band space-borne SAR is sensitive to the effects of surface-level fires in southern African savannahs. The unique availability of frequent and spatially detailed C-band data from the Sentinel-1 SAR constellation provide new opportunities for burned area mapping and systematic monitoring in savannahs systems, for instance, for fine-scale fire propagation studies.
2
Wotton, B. M., R. S. McAlpine und M. W. Hobbs. „The effect of fire front width on surface fire behaviour“. International Journal of Wildland Fire 9, Nr. 4 (1999): 247. http://dx.doi.org/10.1071/wf00021.
Der volle Inhalt der QuelleAnnotation:
To determine the effect of fire front width on surface fire spread rates, a series of simultaneously ignited experimental fires was carried out in a pine plantation. Fires were ignited in plots with widths ranging from 0.5 m to 10 m and were burned in low wind conditions. Flame lengths were small in all fires, ranging from 20 cm to 60 cm. Since pre-heating of the forest litter from flame radiation is assumed to be an important mechanism in the spread of low intensity, low wind surface fires, it then follows that the width of a flaming front should effect on the heating of the fuel to ignition temperatures. Total flame radiation was also measured at a point 50 cm ahead of the advancing flame front for a number of the fires. Experimental results indicate that a flame radiation measured ahead of the fire stays fairly constant once the flame width is between 2 and 5 m. Theoretical flame radiation calculations confirm this trend. Rates of spread between the 5 and 10 metre width fires also appear to be similar; this indicates that, for the type of fires studied, once flame width is greater than about 2 m, radiation from any extra width of fire front has little effect on spread rate.
3
Oris, France, Hugo Asselin, Adam A. Ali, Walter Finsinger und Yves Bergeron. „Effect of increased fire activity on global warming in the boreal forest“. Environmental Reviews 22, Nr. 3 (September 2014): 206–19. http://dx.doi.org/10.1139/er-2013-0062.
Der volle Inhalt der QuelleAnnotation:
Forest fires are an important disturbance in the boreal forest. They are influenced by climate, weather, topography, vegetation, surface deposits, and human activities. In return, forest fires affect the climate through emission of gases and aerosols, and changes in surface albedo, soil processes, and vegetation dynamics. The net effect of these factors is not yet well established but seems to have caused a negative feedback on climate during the 20th century. However, an increase in boreal forest fires is predicted by the end of the 21st century, possibly changing the effect of fires on climate change to a positive feedback that would exacerbate global warming. This review presents (1) an overview of fire regimes and vegetation succession in boreal forests; (2) the effects on climate of combustion emissions and post-fire changes in ecosystem functioning; (3) the effects of fire regime variations on climate, especially on carbon stock and surface albedo; (4) an integrative approach of fire effects on climate dynamics; and (5) the implications of increased fire activity on global warming by calculating the radiative forcing of several factors by 2100 in the boreal region, before discussing the results and exposing the limits of the data at hand. Generally, losses of carbon from forest fires in the boreal region will increase in the future and their effect on the carbon stock (0.37 W/m2/decade) will be greater than the effect of fire on surface albedo (−0.09 W/m2/decade). The net effect of aerosol emissions from boreal fires will likely cause a positive feedback on global warming. This review emphasizes the importance of feedbacks between fires and climate in the boreal forest. It presents limitations and uncertainties to be addressed in future studies, particularly with regards to the effect of CO2 fertilization on forest productivity, which could offset or mitigate the effect of fire.
4
Ansley, RJ, DL Jones, TR Tunnell, BA Kramp und PW Jacoby. „Honey Mesquite Canopy Responses to Single Winter Fires: Relation to Herbaceous Fuel, Weather and Fire Temperature“. International Journal of Wildland Fire 8, Nr. 4 (1998): 241. http://dx.doi.org/10.1071/wf9980241.
Der volle Inhalt der QuelleAnnotation:
Honey mesquite (Prosopis glandulosa Torr.) canopy responses to fire were measured following 20 single winter fires conducted in north Texas. Weather conditions during the fires, understory herbaceous fine fuel (fine fuel) amount and moisture content, fire temperature at 0 cm, 10-30 cm and 1-3 m above ground, and canopy responses were compared. Ten fires occurred on a site where fine fuel was a mixture of cool and warm season grasses (mixed site). The other 10 fires occurred on a site dominated by warm season grasses (warm site). When both sites were included in regressions, peak fire temperature at all heights was positively related to fine fuel amount. Fine fuel amount, fine fuel moisture content, air temperature (AT) and relative humidity (RH) affected fire temperature duration in seconds over 100°C (FTD100) at 1-3 m height, but not at ground level. Mesquite percent above-ground mortality (topkill) increased with increasing fine fuel amount, decreasing fuel moisture content, increasing AT, and decreasing RH. Percent foliage remaining on non-topkilled (NTK) trees was inversely related to fine fuel amount and AT, and positively related to fine fuel moisture content. Effect of fire on mesquite topkill and foliage remaining of NTK trees was strongly affected by RH at the warm site (r2 = 0.92 and 0.82, respectively), but not at the mixed site. This difference was due to RH affecting fuel moisture content (and subsequently fire behavior) to a greater degree at the warm than at the mixed site, because of the lower green tissue content in warm site grasses at the time of burning. Under adequate fine fuel amounts to carry a fire, mesquite canopy responses to fire (i.e., topkill vs, partial canopy defoliation) were largely determined by AT and RH conditions during the fire. This has implications if the management goal is to preserve the mesquite overstory for a savanna result instead of topkilling all trees. Two substudies were conducted during 3 of the fires. Substudy 1 determined mesquite response to fire in 2 plots with different understory herbaceous fuel loads (5,759 vs. 2,547 kg/ha) that were burned under under similar weather conditions. Mesquite topkill was 81% and 11% in the high and low fuel fires, respectively. Under similar weather conditions, fine fuel was an important factor in affecting mesquite responses to fire. However, as demonstrated in the main study, under a variety of weather conditions, AT and RH influenced mesquite response to fire as much or more than did fine fuel. Substudy 2 compared response of mesquite plants with abundant and dry subcanopy fine fuel (3252 kg/ha; fuel moisture 10.4%), or sparse and green subcanopy fuel (1155 kg/ha; fuel moisture 25.9%) to a high intensity fire. All trees were topkilled, including those with low subcanopy fuel, probably from convection heat generated from herbaceous fuel in interspaces between trees. In support of this conclusion, thermocouple data from all 20 fires indicated that canopy responses were more related to fire temperature at 1-3 m than at lower heights. This suggests that the topkill mechanism was due to convective heat within the canopy rather than a girdling effect of fire at stem bases.
5
Francis, Bill B., Iftekhar Hasan und Yun Zhu. „Managerial effect or firm effect: Evidence from the private debt market“. Financial Review 55, Nr. 1 (23.04.2019): 25–59. http://dx.doi.org/10.1111/fire.12196.
Der volle Inhalt der Quelle
6
Potash, Laura L., und James K. Agee. „The effect of fire on red heather (Phyllodoce empetriformis)“. Canadian Journal of Botany 76, Nr. 3 (01.03.1998): 428–33. http://dx.doi.org/10.1139/b98-005.
Der volle Inhalt der QuelleAnnotation:
Red heather (Phyllodoce empetriformis (Sw.) D. Don) recovery after experimental fires and wildfires was studied at five subalpine sites in Washington State, U.S.A. Experimental burn treatments showed that fire had a neutral to positive effect on stem numbers but generally a short-term negative effect on aboveground biomass production. Although there were no differences in effects between experimental burn and clip treatments, long-duration smoldering beyond that documented in our experiments may have more damaging effects. On three wildfire sites, sprouting was vigorous after fire except at one site adjacent to forest cover where significant litter consumption occurred. The duration of fire, rather than its presence or absence, may be an important character of the fire regime in predicting post-fire response of red heather.Key words: red heather, Phyllodoce empetriformis, fire, subalpine meadows, Pacific Northwest.
7
Collins, Luke, Adele Hunter, Sarah McColl-Gausden, Trent D. Penman und Philip Zylstra. „The Effect of Antecedent Fire Severity on Reburn Severity and Fuel Structure in a Resprouting Eucalypt Forest in Victoria, Australia“. Forests 12, Nr. 4 (08.04.2021): 450. http://dx.doi.org/10.3390/f12040450.
Der volle Inhalt der QuelleAnnotation:
Research highlights—Feedbacks between fire severity, vegetation structure and ecosystem flammability are understudied in highly fire-tolerant forests that are dominated by epicormic resprouters. We examined the relationships between the severity of two overlapping fires in a resprouting eucalypt forest and the subsequent effect of fire severity on fuel structure. We found that the likelihood of a canopy fire was the highest in areas that had previously been exposed to a high level of canopy scorch or consumption. Fuel structure was sensitive to the time since the previous canopy fire, but not the number of canopy fires. Background and Objectives—Feedbacks between fire and vegetation may constrain or amplify the effect of climate change on future wildfire behaviour. Such feedbacks have been poorly studied in forests dominated by highly fire-tolerant epicormic resprouters. Here, we conducted a case study based on two overlapping fires within a eucalypt forest that was dominated by epicormic resprouters to examine (1) whether past wildfire severity affects future wildfire severity, and (2) how combinations of understorey fire and canopy fire within reburnt areas affect fuel properties. Materials and Methods—The study focused on ≈77,000 ha of forest in south-eastern Australia that was burnt by a wildfire in 2007 and reburnt in 2013. The study system was dominated by eucalyptus trees that can resprout epicormically following fires that substantially scorch or consume foliage in the canopy layer. We used satellite-derived mapping to assess whether the severity of the 2013 fire was affected by the severity of the 2007 fire. Five levels of fire severity were considered (lowest to highest): unburnt, low canopy scorch, moderate canopy scorch, high canopy scorch and canopy consumption. Field surveys were then used to assess whether combinations of understorey fire (<80% canopy scorch) and canopy fire (>90% canopy consumption) recorded over the 2007 and 2013 fires caused differences in fuel structure. Results—Reburn severity was influenced by antecedent fire severity under severe fire weather, with the likelihood of canopy-consuming fire increasing with increasing antecedent fire severity up to those classes causing a high degree of canopy disturbance (i.e., high canopy scorch or canopy consumption). The increased occurrence of canopy-consuming fire largely came at the expense of the moderate and high canopy scorch classes, suggesting that there was a shift from crown scorch to crown consumption. Antecedent fire severity had little effect on the severity patterns of the 2013 fire under nonsevere fire weather. Areas affected by canopy fire in 2007 and/or 2013 had greater vertical connectivity of fuels than sites that were reburnt by understorey fires, though we found no evidence that repeated canopy fires were having compounding effects on fuel structure. Conclusions—Our case study suggests that exposure to canopy-defoliating fires has the potential to increase the severity of subsequent fires in resprouting eucalypt forests in the short term. We propose that the increased vertical connectivity of fuels caused by resprouting and seedling recruitment were responsible for the elevated fire severity. The effect of antecedent fire severity on reburn severity will likely be constrained by a range of factors, such as fire weather.
8
Bradstock, RA, und M. Bedward. „Simulation of the Effect of Season of Fire on Post-Fire Seedling Emergence of Two Banksia Species Based on Long-Term Rainfall Records“. Australian Journal of Botany 40, Nr. 1 (1992): 75. http://dx.doi.org/10.1071/bt9920075.
Der volle Inhalt der QuelleAnnotation:
Simulations were used to investigate the effect of season of fire on seedling emergence in Banksia ericifolia and B. serrata in the Sydney region, New South Wales. The simulations were based on models of soil-surface moisture in response to rainfall, seedling emergence response to soil moisture and post-fire seed release from fruits as determined by fire intensity, derived from field and laboratory studies. Fires were modelled on the first day of each calendar month for a 50-year period. Levels of post-fire seedling emergence were calculated using rainfall data from the Sydney Observatory for the corresponding period (1931-1980). Trends in seedling emergence as a function of month of fire were examined. Alternative sets of simulations were performed to assess the effect of variations in post-dispersal seed mortality, fire intensity and induced summer dormancy. In both species, mean emergence was affected by season of fire only when a 10% per month level of post-dispersal seed mortality was simulated (there was no fire-season effect at lower mortality levels). Highest predicted emergence occurred after summer fires and lowest emergence after winter fires. A reduction in rate of seed release (lower intensity fire) and induced seed dormancy in summer also had a minor effect with respect to fire-season in B. ericifolia. Reported levels of post-dispersal seed mortality in Banksia species are often high, and therefore, the simulations suggested that there will be an effect of fire season on seedling emergence. However, given the high level of year to year variation in seasonal rainfall in the Sydney region, fire-season effects are not predictable in the short term. In the longer term, the timing of fire relative to sequences of wet and dry years may be of equal importance to season of fire in its effect on populations of these species.
9
Bowman-Prideaux, Chris, Beth A. Newingham und Eva K. Strand. „The Effect of Seeding Treatments and Climate on Fire Regimes in Wyoming Sagebrush Steppe“. Fire 4, Nr. 2 (27.03.2021): 16. http://dx.doi.org/10.3390/fire4020016.
Der volle Inhalt der QuelleAnnotation:
Wildfire size and frequency have increased in the western United States since the 1950s, but it is unclear how seeding treatments have altered fire regimes in arid steppe systems. We analyzed how the number of fires since 1955 and the fire return interval and frequency between 1995 and 2015 responded to seeding treatments, anthropogenic features, and abiotic landscape variables in Wyoming big sagebrush ecosystems. Arid sites had more fires than mesic sites and fire return intervals were shortest on locations first treated between 1975 and 2000. Sites drill seeded before the most recent fire had fewer, less frequent fires with longer fire return intervals (15–20 years) than aerially seeded sites (intervals of 5–8 years). The response of fire regime variables at unseeded sites fell between those of aerial and drill seeding. Increased moisture availability resulted in decreased fire frequency between 1994 and 2014 and the total number of fires since 1955 on sites with unseeded and aerially pre-fire seeding, but fire regimes did not change when drill seeded. Greater annual grass biomass likely contributed to frequent fires in the arid region. In Wyoming big sagebrush steppe, drill seeding treatments reduced wildfire risk relative to aerial seeded or unseeded sites.
10
Marino, Eva, Carmen Hernando, Javier Madrigal, Carmen Díez und Mercedes Guijarro. „Fuel management effectiveness in a mixed heathland: a comparison of the effect of different treatment types on fire initiation risk“. International Journal of Wildland Fire 21, Nr. 8 (2012): 969. http://dx.doi.org/10.1071/wf11111.
Der volle Inhalt der QuelleAnnotation:
Fuel management is commonly used to reduce fire risk in fire-prone shrubland, but information about the real efficacy of the different techniques is scarce. In this study, we assessed in the laboratory the effects of different treatment types on fire initiation risk in a mixed heathland. The effects of two mechanical treatments and of prescribed burning were compared with untreated vegetation. Flammability tests were performed in samples of the regenerated shrubs and fine ground fuels present 2 years after treatments. Results indicate that all treatments were effective in reducing fire initiation risk in regenerated shrubs, but not in fine ground fuels. Recovery of vegetation differed between treatments, and treatment type had a significant effect on flammability, mainly affecting fire sustainability. Wind speed had a minor effect on shrub fuel flammability, whereas fuel moisture had a significant effect. The flammability of fine ground fuels differed significantly depending on fuel moisture content, even at the low levels tested. Logistic models were fitted to predict successful fire sustainability, and the probability of initial propagation was obtained as a function of treatment type, fuel moisture content and fuel structural characteristics. This study provides new insights into wildfire prevention in shrubland, and compares the effectiveness of different fuel treatment techniques.
11
Rao, Leela E., John R. Matchett, Matthew L. Brooks, Robert F. Johnson, Richard A. Minnich und Edith B. Allen. „Relationships between annual plant productivity, nitrogen deposition and fire size in low-elevation California desert scrub“. International Journal of Wildland Fire 24, Nr. 1 (2015): 48. http://dx.doi.org/10.1071/wf13152.
Der volle Inhalt der QuelleAnnotation:
Although precipitation is correlated with fire size in desert ecosystems and is typically used as an indirect surrogate for fine fuel load, a direct link between fine fuel biomass and fire size has not been established. In addition, nitrogen (N) deposition can affect fire risk through its fertilisation effect on fine fuel production. In this study, we examine the relationships between fire size and precipitation, N deposition and biomass with emphasis on identifying biomass and N deposition thresholds associated with fire spreading across the landscape. We used a 28-year fire record of 582 burns from low-elevation desert scrub to evaluate the relationship of precipitation, N deposition and biomass with the distribution of fire sizes using quantile regression. We found that models using annual biomass have similar predictive ability to those using precipitation and N deposition at the lower to intermediate portions of the fire size distribution. No distinct biomass threshold was found, although within the 99th percentile of the distribution fire size increased with greater than 125 g m–2 of winter fine fuel production. The study did not produce an N deposition threshold, but did validate the value of 125 g m–2 of fine fuel for spread of fires.
12
Cruz, Miguel G., Richard J. Hurley, Rachel Bessell und Andrew L. Sullivan. „Fire behaviour in wheat crops – effect of fuel structure on rate of fire spread“. International Journal of Wildland Fire 29, Nr. 3 (2020): 258. http://dx.doi.org/10.1071/wf19139.
Der volle Inhalt der QuelleAnnotation:
A field-based experimental study was conducted in 50×50m square plots to investigate the behaviour of free-spreading fires in wheat to quantify the effect of crop condition (i.e. harvested, unharvested and harvested and baled) on the propagation rate of fires and their associated flame characteristics, and to evaluate the adequacy of existing operational prediction models used in these fuel types. The dataset of 45 fires ranged from 2.4 to 10.2kmh−1 in their forward rate of fire spread and 3860 and 28000 kWm−1 in fireline intensity. Rate of fire spread and flame heights differed significantly between crop conditions, with the unharvested condition yielding the fastest spreading fires and tallest flames and the baled condition having the slowest moving fires and lowest flames. Rate of fire spread in the three crop conditions corresponded directly with the outputs from the models of Cheney et al. (1998) for grass fires: unharvested wheat → natural grass; harvested wheat (~0.3m tall stubble) → grazed or cut grass; and baled wheat (<0.1m tall stubble) → eaten-out grass. These models produced mean absolute percent errors between 21% and 25% with reduced bias, a result on par with the most accurate published fire spread model evaluations.
13
Pimont, F., J. L. Dupuy und R. R. Linn. „Coupled slope and wind effects on fire spread with influences of fire size: a numerical study using FIRETEC“. International Journal of Wildland Fire 21, Nr. 7 (2012): 828. http://dx.doi.org/10.1071/wf11122.
Der volle Inhalt der QuelleAnnotation:
Wind and slope are commonly accepted to be major environmental factors affecting the manner in which wildfires propagate. Fire-line width has been observed as having a significant effect on fire behaviour in some experimental fires. Most wildfire behaviour models and fire behaviour prediction systems take wind and slope effects into account when determining the rate of spread, but do not take into account the influence of fire width on the coupled effects of slope and wind. In the present study, the effect of topographic slope on rate of spread under weak (1 m s–1), moderate (5 m s–1) and strong (12 m s–1) wind speeds is investigated for two different initial fire widths (20 and 50 m) in a typical Mediterranean garrigue, using the coupled atmosphere–fire HIGRAD-FIRETEC model. The results show non-trivial combined effects and suggest a strong effect of fire width under low-wind conditions, especially for steep slopes. Simulated spread rates were compared with predictions of existing models of operational systems and a reasonable agreement was found. Additional exploratory simulations of fire behaviour in small canyons are provided. These simulations show how combined effects of wind, slope and fire-front size can induce different fire behaviours that operational models could fail to predict and provide insight that could be valuable for analysis of blow-up fires. These preliminary results also suggest that 3D physically based models could be used in the future to investigate how operational models can include non-local effects of fire propagation.
14
Cruz, Miguel G., Jim S. Gould, Susan Kidnie, Rachel Bessell, David Nichols und Alen Slijepcevic. „Effects of curing on grassfires: II. Effect of grass senescence on the rate of fire spread“. International Journal of Wildland Fire 24, Nr. 6 (2015): 838. http://dx.doi.org/10.1071/wf14146.
Der volle Inhalt der QuelleAnnotation:
The capacity to predict fire dynamics in fuel beds comprised of live and dead fuel components is constrained by our limited understanding of the effects of live fuels on fire propagation. A field-based experimental burning program was conducted to specifically address the effect of the degree of curing, the proportion of dead fuels in the fuel bed, on fire propagation in grasslands. Experimental fires were conducted at two sites characterised by structurally distinct fuels with curing levels varying between 20% and 100%. Fire sustainability experiments showed that fire propagation can occur down to curing levels as low as 20%. Rate of fire spread varied between 41.7 and 102 m min–1 in fully cured fuels and between 2.8 and 43.5 m min–1 in partially cured grasslands. The degree of curing was found to be the best variable describing the damping effect of live fuels in a natural, senescing grassland. Live fuel moisture content by itself was not found to be related to the damping effect of live fuels on the rate of fire spread. Existing models for the effect of grass curing on fire behaviour presently used in Australia were found to under-predict the rate of forward fire spread in partially cured grasslands. A new curing relationship for southern Australian grasslands derived from the study results is proposed.
15
Doumas, Sandra L., und John L. Koprowski. „Effect of heterogeneity in burn severity on Mexican fox squirrels following the return of fire“. International Journal of Wildland Fire 22, Nr. 3 (2013): 405. http://dx.doi.org/10.1071/wf12046.
Der volle Inhalt der QuelleAnnotation:
After decades of suppression, fire has returned to many forested areas of the western United States. Understanding responses of wildlife species to fire is essential to native species conservation because contemporary fires may not have the same effects as historical fires. Recent fires in the Chiricahua Mountains of Arizona provided an opportunity to investigate effects of fire heterogeneity on habitat selection of a native wildlife species. We used radiotelemetry to determine home ranges of Mexican fox squirrels (Sciurus nayaritensis chiricahuae) within fire-influenced forests. We then applied resource-utilisation functions to evaluate associations of use intensity within home ranges to heterogeneity of burn severity at two spatial scales. Squirrels used areas with moderate levels of burn heterogeneity at large scale more than areas of low or high heterogeneity. Squirrels used small (<0.5 ha) or narrow (<120 m) severely burnt patches, but incorporated only edges of large patches into home ranges. Use of burnt forests by Mexican fox squirrels demonstrates the complexities of fire’s effects on wildlife. Our results contribute to an understanding of the role and effect of fire in forest ecosystems and implications for wildlife conservation.
16
Hantson, Stijn, Gitta Lasslop, Silvia Kloster und Emilio Chuvieco. „Anthropogenic effects on global mean fire size“. International Journal of Wildland Fire 24, Nr. 5 (2015): 589. http://dx.doi.org/10.1071/wf14208.
Der volle Inhalt der QuelleAnnotation:
Wildland fires are an important agent in the earth’s system. Multiple efforts are currently in progress to better represent wildland fires in earth system models. Although wildland fires are a natural disturbance factor, humans have an important effect on fire occurrence by directly igniting and suppressing fires and indirectly influencing fire behaviour by changing land cover and landscape structure. Although these factors are recognised, their quantitative effect on fire growth and burned area are not well understood and therefore only partly taken into account in current process-based fire models. Here we analyse the influence of humans on mean fire size globally. The mean fire size was extracted from the global Moderate Resolution Imaging Spectroradiometer (MODIS) burned area product MCD45. We found a linear decreasing trend between population density and observed mean fire size over the globe, as well as a negative effect of cropland cover and net income. We implemented the effect of population density on fire growth in a global vegetation model including a process-based fire model (SPITFIRE–JSBACH). When including this demographic control, spatial trends in modelled fraction of burned area generally improved when compared with satellite-derived burned area data. More process-based solutions to limit fire spread are needed in the future, but the empirical relations described here serve as an intermediate step to improve current fire models.
17
de Groot, W. J., P. M. Bothwell, S. W. Taylor, B. M. Wotton, B. J. Stocks und M. E. Alexander. „Jack pine regeneration and crown fires“. Canadian Journal of Forest Research 34, Nr. 8 (01.08.2004): 1634–41. http://dx.doi.org/10.1139/x04-073.
Der volle Inhalt der QuelleAnnotation:
The effect of crown fires on Pinus banksiana Lamb. regeneration was studied in separate forest- and cone-burning experiments. Nine plots (0.562.25 ha) of jack pine trees near Fort Providence, Northwest Territories, were burned using crown fires to determine the effects of fire intensity, rate of fire spread, depth of burn, and postfire duff depth on seed viability and regeneration. Fire intensities were 36 902 93 476 kW/m, and fire spread rates were 2470 m/min. Depths of burn were low (2.03.6 cm), and postfire duff depths averaged 2.05.5 cm. Postfire seed rain was highly variable (64634 seeds/m2), but seed viability was near 67% on all plots. Jack pine regeneration was also highly variable (779 seedlings/m2). In the cone-burning experiment, the germination rate increased from 41% (unheated cones) to 64% after 10 s of burning but decreased sharply after 30 s. Flame temperature did not significantly affect viability. Cone-burning results suggest that the postfire seed rain originated from the upper canopy, where flame duration was 515 s, and seed in the lower canopy was consumed by fire. Seed rain and regeneration were primarily influenced by understory fine fuel consumption (and therefore, fire intensity), tree height, and live crown base height.
18
Weier, Anna, Ian J. Radford, Sofia L. J. Oliveira und Michael J. Lawes. „Recently but infrequently burnt breeding sites are favoured by threatened Gouldian finches (Erythrura gouldiae)“. International Journal of Wildland Fire 25, Nr. 12 (2016): 1281. http://dx.doi.org/10.1071/wf16105.
Der volle Inhalt der QuelleAnnotation:
Frequent and extensive fires are becoming increasingly common throughout the tropical savannas of northern Australia. This fire regime has been implicated in both habitat alteration and losses of biodiversity. Granivorous birds are particularly affected because of the effect of fire on grass seed availability. The endemic Gouldian finch (Erythrura gouldiae) has experienced population declines in recent decades, potentially in response to changed fire regimes. Using breeding data from monitored artificial nest-boxes, this study examined the choice of breeding site by Gouldian finches in response to several attributes of the prevailing fire regime. The fire regime was characterised using remote sensing analysis of annual fire scars. Time since last fire and fire frequency were the most useful predictors of breeding site occupancy. Gouldian finches favoured recently burnt sites (previous dry season), but also sites that were infrequently burnt (return time of 2–3 years). Consequently, under the current regime of many frequent fires, Gouldian finches move among breeding sites and display low seasonal site fidelity. Our findings provide support for the notion that the Gouldian finch favours a fine-grain patch-mosaic fire regime and that contemporary large-scale fire regimes are likely contributing to their decline.
19
Collins, L., R. A. Bradstock und T. D. Penman. „Can precipitation influence landscape controls on wildfire severity? A case study within temperate eucalypt forests of south-eastern Australia“. International Journal of Wildland Fire 23, Nr. 1 (2014): 9. http://dx.doi.org/10.1071/wf12184.
Der volle Inhalt der QuelleAnnotation:
The environmental, economic and social impacts of wildfires depend on spatial patterns of fire severity. An understanding as to how drivers of fire severity vary across broad vegetation communities exists. However, examination of variation within communities in response to gradients of moisture has received little attention so far. This study examined whether relationships between environmental variables (i.e. fire weather, topography and fuel age) and fire severity were modified by increasing mean annual precipitation. Understorey fires were more likely to occur in young fuels (i.e. <5 years since fire) in drier sites, although this effect diminished as precipitation increased. The probability of occurrence of understorey fires under non-extreme weather and on steep slopes was reduced in wetter areas. Relationships between crown fire and weather, topography and fuel age were largely unaltered by the precipitation gradient, with only a marginally significant interaction occurring between weather and mean annual precipitation. Greater fine fuel accumulation associated with increased precipitation presumably reduced fuel limitations imposed by environmental factors (i.e. fire weather, slope, fuel age), altering their relative control on the probability of understorey fire. The probability of crown fires is predominantly driven by fire weather and is consequently less sensitive to precipitation gradients. Consideration of precipitation gradients will be necessary when identifying controls of fire severity and devising effective fire management strategies.
20
Penman, Trent D., Dan A. Ababei, Jane G. Cawson, Brett A. Cirulis, Thomas J. Duff, William Swedosh und James E. Hilton. „Effect of weather forecast errors on fire growth model projections“. International Journal of Wildland Fire 29, Nr. 11 (2020): 983. http://dx.doi.org/10.1071/wf19199.
Der volle Inhalt der QuelleAnnotation:
Fire management agencies use fire behaviour simulation tools to predict the potential spread of a fire in both risk planning and operationally during wildfires. These models are generally based on underlying empirical or quasi-empirical relations and rarely are uncertainties considered. Little attention has been given to the quality of the input data used during operational fire predictions. We examined the extent to which error in weather forecasts can affect fire simulation results. The study was conducted using data representing the State of Victoria in south-eastern Australia, including grassland and forest conditions. Two fire simulator software packages were used to compare fire growth under observed and forecast weather. We found that error in the weather forecast data significantly altered the predicted size and location of fires. Large errors in wind speed and temperature resulted in an overprediction of fire size, whereas large errors in wind direction resulted in an increased spatial error in the fire’s location. As the fire weather intensified, fire predictions using forecast weather under predicted fire size, potentially resulting in greater risks to the community. These results highlight the importance of on-ground intelligence during wildfires and the use of ensembles to improve operational fire predictions.
21
Stanis, Shannon, Jan Wiedenbeck und Mike R. Saunders. „Effect of Prescribed Fire on Timber Volume and Grade in the Hoosier National Forest“. Forest Science 65, Nr. 6 (14.06.2019): 714–24. http://dx.doi.org/10.1093/forsci/fxz039.
Der volle Inhalt der QuelleAnnotation:
AbstractLow-intensity surface fire is prescribed in eastern North American hardwood stands prior to overstory harvest in order to improve regeneration and recruitment of oak and other fire-tolerant and fire-adapted species. However, this use of prescribed fire potentially can reduce timber value. We inventoried overstory trees (>10 in. diameter at breast height) in 54 oak-dominated stands with varied prescribed fire histories and aspects in southern Indiana. We then documented the extent of prescribed fire damage (i.e., wounds) to overstory trees and quantified both the relative stand volume of timber loss and the proportion of trees that had tree grade reductions because of prescribed fire. Generally, as a stand received more prescribed fires, more trees were scarred, the relative volume lost increased, and a higher proportion of trees declined in grade. Overall, burned stands experienced less than 10 percent sawtimber volume loss, regardless of the number of prescribed fires and aspect. Less than 3 percent of trees, study-wide, had reduced grade because of prescribed fire. Grade and volume reductions varied by species, however. Our results suggest that prescribed fire has a minor economic impact on standing timber, particularly when timber is harvested within two decades of the first fire.
22
Bradstock, R. A., M. G. Tozer und D. A. Keith. „Effects of High Frequency Fire on Floristic Composition and Abundance in a Fire-prone Heathland near Sydney“. Australian Journal of Botany 45, Nr. 4 (1997): 641. http://dx.doi.org/10.1071/bt96083.
Der volle Inhalt der QuelleAnnotation:
The effect of high frequency fire regimes on a coastal heathland north of Sydney was examined. Plant community composition and species frequency and density (of a subset of species) were compared among sites burnt by either one, two or three fires in the period 1988-1990 inclusive. Constrained ordination indicated that number of fires had a significant effect on floristic composition. Site variables also had a significant effect on floristics and frequency and accounted for a larger proportion of variation than did number of fires. Analyses of deviance indicated that frequency in 13 species was unaffected by fire regimes or site factors. Site factors significantly affected frequency in 42 species. Frequency in seven species was significantly affected by fire regimes (no site effect). In six of these, frequency was lower in areas subjected to either two or three fires compared to one fire. Three of these species were obligate seeders. Frequency in the other species (a herbaceous resprouter) was significantly higher in the area subjected to two fires. There was no significant effect of fire on species richness. Densities of seven out of a subset of eight species were also significantly affected by fire (two obligate seeder spp.) and site factors (four spp.), Significantly lower densities were related to multiple fires. The study indicated that regimes of frequent fire can deplete populations of some heathland species with the dominant shrub species, Banksia ericifolia L.f., being most affected.
23
McAlpine, RS. „Testing the Effect of Fuel Consumption on Fire Spread Rate“. International Journal of Wildland Fire 5, Nr. 3 (1995): 143. http://dx.doi.org/10.1071/wf9950143.
Der volle Inhalt der QuelleAnnotation:
It has been theorized that the amount of fuel involved in a fire front can influence the rate of spread of the fire. Three data sets are examined in an attempt to prove this relationship. The first, a Canadian Forest Service database of over 400 experimental, wild, and prescribed fires showed a weak relationship in some fuel complexes. The second, a series of field experimental fires conducted to isolate the relationship, showed a small effect. The final data set, from a series of 47 small plots (3m x 3m) burned with a variety of fuel loadings, also show a weak relationship. While a relationship was shown to exist, it is debatable whether it should be included in a fire behavior prediction system. Inherent errors associated with predicting fuel consumption can be compounded, causing additional, more critical, errors with the derived fire spread rate.
24
Vasconcelos, Heraldo L., Elmo B. A. Koch, Flávio Camarota, Richard Tito, Lino A. Zuanon und Jonas Maravalhas. „Severe fires alter the outcome of the mutualism between ants and a Neotropical savanna tree“. Biological Journal of the Linnean Society 131, Nr. 3 (09.09.2020): 476–86. http://dx.doi.org/10.1093/biolinnean/blaa132.
Der volle Inhalt der QuelleAnnotation:
Abstract Physical disturbances, such as fire, may affect the relationship between ants and plants. We evaluated the extent to which severe fires alter the protective effect of ants against the herbivores of an extrafloral-nectary bearing tree. We performed an ant removal experiment and sampled the ant fauna from the same trees over 4 years: the pre-fire year, the fire-year, and again 1 and 2 years later. Ants reduced insect herbivory in the pre-fire year and in the fire-year but failed to provide any plant protection in the two years after fire. The magnitude of the ant effect on herbivory did not differ between the pre-fire year and the fire-year. Fire reduced the abundance of ants with strictly arboreal-nesting habits. However, in the fire year (but not in the subsequent ones), this decline was compensated by an increase in the abundance of arboreal generalists and ground-nesting ants foraging in trees. Our results indicate that severe fires can affect the strength and direction of the ant effects on herbivory by altering the structure of the arboreal ant community and the abundance of insect herbivores. Fire disturbance is thus an important factor of conditionality of ant-plant mutualisms in fire-prone habitats, like the Cerrado savannas.
25
Cochrane, Mark A., und William F. Laurance. „Fire as a large-scale edge effect in Amazonian forests“. Journal of Tropical Ecology 18, Nr. 3 (26.03.2002): 311–25. http://dx.doi.org/10.1017/s0266467402002237.
Der volle Inhalt der QuelleAnnotation:
Amazonian forests are being rapidly cleared, and the remaining forest fragments appear unusually vulnerable to fire. This occurs because forest remnants have dry, fire-prone edges, are juxtaposed with frequently burned pastures, and are often degraded by selective logging, which increases forest desiccation and fuel loading. Here we demonstrate that in eastern Amazonia, fires are operating as a large-scale edge effect in the sense that most fires originate outside fragments and penetrate considerable distances into forest interiors. Multi-temporal analyses of satellite imagery from two frontier areas reveal that fire frequency over 12-14-y periods was substantially elevated within at least 2400 m of forest margins. Application of these data with a mathematical core-area model suggests that even large forest remnants (up to several hundred thousand ha in area) could be vulnerable to edge-related fires. The synergistic interactions of forest fragmentation, logging and human-ignited fires pose critical threats to Amazonian forests, particularly in more seasonal areas of the basin.
26
King, Karen J., Ross A. Bradstock, Geoffrey J. Cary, Joanne Chapman und Jon B. Marsden-Smedley. „The relative importance of fine-scale fuel mosaics on reducing fire risk in south-west Tasmania, Australia“. International Journal of Wildland Fire 17, Nr. 3 (2008): 421. http://dx.doi.org/10.1071/wf07052.
Der volle Inhalt der QuelleAnnotation:
In many landscapes, an important fire management objective is to reduce the negative impacts from unplanned fires on people, property and ecological values. In Australia, there exists an inherent assumption that high spatial variability in fire ages and hence fuel loads will have negative effects on both the incidence and spread of subsequent fires, and will enhance ecological values. A recent study using the process-based computer simulation model FIRESCAPE-SWTAS predicted several relationships between prescribed burn treatment levels and spatial patterning and management objectives in south-west Tasmania, Australia. The present study extended this investigation to additionally explore the effects of prescribed burning treatment unit size on unplanned fire incidence and area burned both in the general landscape and specifically in fire-intolerant vegetation. Simulation results suggest that treatment level had the greatest influence on modifying fire effects, whereas treatment unit size had the least effect. The model predicted that all three parameters interacted to determine the mean annual area burnt by unplanned fires. In fire-intolerant vegetation, treatment unit size did not influence the incidence of unplanned fires and the area burnt by unplanned fires in these communities. Where significant differences were evident, fire risk was reduced by higher treatment levels, deterministic spatial patterns of burning units, and smaller burning unit sizes.
27
Oliveira, Tiago M., Ana M. G. Barros, Alan A. Ager und Paulo M. Fernandes. „Assessing the effect of a fuel break network to reduce burnt area and wildfire risk transmission“. International Journal of Wildland Fire 25, Nr. 6 (2016): 619. http://dx.doi.org/10.1071/wf15146.
Der volle Inhalt der QuelleAnnotation:
Wildfires pose complex challenges to policymakers and fire agencies. Fuel break networks and area-wide fuel treatments are risk-management options to reduce losses from large fires. Two fuel management scenarios covering 3% of the fire-prone Algarve region of Portugal and differing in the intensity of treatment in 120-m wide fuel breaks were examined and compared with the no-treatment option. We used the minimum travel time algorithm to simulate the growth of 150 000 fires under the weather conditions historically associated with large fires. Fuel break passive effects on burn probability, area burned, fire size distribution and fire transmission among 20 municipalities were analysed. Treatments decreased large-fire incidence and reduced overall burnt area up to 17% and burn probability between 4% and 31%, depending on fire size class and treatment option. Risk transmission among municipalities varied with community. Although fire distribution shifted and large events were less frequent, mean treatment leverage was very low (1 : 26), revealing a very high cost–benefit ratio and the need for engaging forest owners to act in complementary area-wide fuel treatments. The study assessed the effectiveness of a mitigating solution in a complex socioecological system, contributing to a better-informed wildland fire risk governance process among stakeholders.
28
RUBAJ, Tomasz. „FIELD ARTILLERY IN JOINT FIRE SUPPORT“. Scientific Journal of the Military University of Land Forces 164, Nr. 2 (01.03.2012): 35–51. http://dx.doi.org/10.5604/01.3001.0002.2782.
Der volle Inhalt der QuelleAnnotation:
Joint fires are defined as fires produced during the employment of forces from two or more components in coordinated action to produce desired effects in the support of a common objective. When joint fires assist air, land, maritime, and SOF to move, manoeuvre, and control territory, populations, airspace, and key waters are called Joint Fire Support (JFS).According to the latest standardization agreements, the range of capabilities to influence enemy forces has been extended to the sphere of influence in order to achieve the desired effect, not only a physical one but also a psychological one. That way Joint Fire Support (JFS) and Effects is the coordinated and integrated employment of all weapon platforms delivering fires (including land, air, naval indirect fires) to achieve the required effects on ground targets to support land operations in the full spectrum of conflict. It encompasses the integration of indirect fires and effects in order to influence the adversary forces, installations or functions. Joint Fire Support Element (JFSE) could either encompass influence elements as, for example, PSYOPS, CIMIC, EW, or be incorporated in a wider cell dealing with overall influence activities.The necessity of conducting JFS more often occurs at the tactical level because of the complexity of contemporary operational environment (non-linear and non-continuous battlespace, dispersion of forces, high operations tempo, and short time of reaction). For this reason, JFS should be coordinated, synchronized and integrated in the framework of three vital components: surveillance and target acquisition (STA), command and control (C2), weapon (delivering) systems. Among them, Field Artillery Forces possess a relevant part of each of the abovementioned subsystems and their capabilities. The article presents selected solutions from different countries, experimented so far, and experiences from current military, peace and stabilization operations, indicating the plans and directions for further development of Joint Fire Support and Effect.
29
Davies, Kirk W., Amanda Gearhart, Chad S. Boyd und Jon D. Bates. „Fall and spring grazing influence fire ignitability and initial spread in shrub steppe communities“. International Journal of Wildland Fire 26, Nr. 6 (2017): 485. http://dx.doi.org/10.1071/wf17065.
Der volle Inhalt der QuelleAnnotation:
The interaction between grazing and fire influences ecosystems around the world. However, little is known about the influence of grazing on fire, in particular ignition and initial spread and how it varies by grazing management differences. We investigated effects of fall (autumn) grazing, spring grazing and not grazing on fuel characteristics, fire ignition and initial spread during the wildfire season (July and August) at five shrub steppe sites in Oregon, USA. Both grazing treatments decreased fine fuel biomass, cover and height, and increased fuel moisture, and thereby decreased ignition and initial spread compared with the ungrazed treatment. However, effects differed between fall and spring grazing. The probability of initial spread was 6-fold greater in the fall-grazed compared with the spring-grazed treatment in August. This suggests that spring grazing may have a greater effect on fires than fall grazing, likely because fall grazing does not influence the current year’s plant growth. Results of this study also highlight that the grazing–fire interaction will vary by grazing management. Grazing either the fall or spring before the wildfire season reduces the probability of fire propagation and, thus, grazing is a potential fuel management tool.
30
Pimont, François, Jean-Luc Dupuy, Yves Caraglio und Dominique Morvan. „Effect of vegetation heterogeneity on radiative transfer in forest fires“. International Journal of Wildland Fire 18, Nr. 5 (2009): 536. http://dx.doi.org/10.1071/wf07115.
Der volle Inhalt der QuelleAnnotation:
Wildland fires are driven by the heat transferred from the fire source to the unburned fuel bed and this transfer is likely to be affected by the spatial heterogeneity of fuel element distributions at different scales from shoot to stand. In a context of theoretical fire modelling, we investigated the impact of a departure from randomness of fuel distributions on the radiative transfer of energy. Our methodology was derived from the approach developed for solar radiation in heterogeneous canopies or clouds and was modified to suit an analysis of fire behaviour. Some fine and coarse fuel distributions for several Mediterranean fuel types were derived from field measurements and plant architecture modelling. A comparison of the average irradiances in different fuels showed whether heterogeneity effects were significant or not. Results showed that both marked spatial variability in fuel distribution (low cover fraction and large clumps) and a high vegetation density were required to provide significant effects. The radiative transfer in heterogeneous maritime pines and in dense shrub stands was significantly affected by heterogeneity, mainly at crown and shoot scales. Less pronounced effects were observed in Aleppo pine stand and light shrubs. In terms of fuel modelling, the 2-m resolution used in a fire model such as FIRETEC seems to be sufficient for the fuel types investigated here, with the exception of dense small clumps in shrublands. An effective coefficient was proposed for these latter cases.
31
Lawes, Michael J., Brett P. Murphy, Alaric Fisher, John C. Z. Woinarski, Andrew C. Edwards und Jeremy Russell-Smith. „Small mammals decline with increasing fire extent in northern Australia: evidence from long-term monitoring in Kakadu National Park“. International Journal of Wildland Fire 24, Nr. 5 (2015): 712. http://dx.doi.org/10.1071/wf14163.
Der volle Inhalt der QuelleAnnotation:
Small mammal (<2 kg) numbers have declined dramatically in northern Australia in recent decades. Fire regimes, characterised by frequent, extensive, late-season wildfires, are implicated in this decline. Here, we compare the effect of fire extent, in conjunction with fire frequency, season and spatial heterogeneity (patchiness) of the burnt area, on mammal declines in Kakadu National Park over a recent decadal period. Fire extent – an index incorporating fire size and fire frequency – was the best predictor of mammal declines, and was superior to the proportion of the surrounding area burnt and fire patchiness. Point-based fire frequency, a commonly used index for characterising fire effects, was a weak predictor of declines. Small-scale burns affected small mammals least of all. Crucially, the most important aspects of fire regimes that are associated with declines are spatial ones; extensive fires (at scales larger than the home ranges of small mammals) are the most detrimental, indicating that small mammals may not easily escape the effects of large and less patchy fires. Notwithstanding considerable management effort, the current fire regime in this large conservation reserve is detrimental to the native mammal fauna, and more targeted management is required to reduce fire size.
32
Parks, Sean A., Carol Miller, Lisa M. Holsinger, L. Scott Baggett und Benjamin J. Bird. „Wildland fire limits subsequent fire occurrence“. International Journal of Wildland Fire 25, Nr. 2 (2016): 182. http://dx.doi.org/10.1071/wf15107.
Der volle Inhalt der QuelleAnnotation:
Several aspects of wildland fire are moderated by site- and landscape-level vegetation changes caused by previous fire, thereby creating a dynamic where one fire exerts a regulatory control on subsequent fire. For example, wildland fire has been shown to regulate the size and severity of subsequent fire. However, wildland fire has the potential to influence other properties of subsequent fire. One of those properties – the extent to which a previous wildland fire inhibits new fires from igniting and spreading within its perimeter – is the focus of our study. In four large wilderness study areas in the western United States (US), we evaluated whether or not wildland fire regulated the ignition and spread (hereafter occurrence) of subsequent fire. Results clearly indicate that wildland fire indeed regulates subsequent occurrence of fires ≥ 20 ha in all study areas. We also evaluated the longevity of the regulating effect and found that wildland fire limits subsequent fire occurrence for nine years in the warm/dry study area in the south-western US and over 20 years in the cooler/wetter study areas in the northern Rocky Mountains. Our findings expand upon our understanding of the regulating capacity of wildland fire and the importance of wildland fire in creating and maintaining resilience to future fire events.
33
Viegas, Domingos X. „On the existence of a steady state regime for slope and wind driven fires“. International Journal of Wildland Fire 13, Nr. 1 (2004): 101. http://dx.doi.org/10.1071/wf03008.
Der volle Inhalt der QuelleAnnotation:
Forest fire behaviour analysis and prediction is based on the assumption that for a given set of boundary conditions a steady-state of fire propagation exists with a well-defined rate of spread. The evolution of a fire front for linear and point ignited fires is analysed and it is shown that, even in nominally uniform and permanent conditions, the rate of spread of the head fire does not remain constant in the general case of slope- and wind-driven fires due to joint convection and radiation effects. The basic case of a linear fire front without slope and without wind is one of the few cases for which the rate of spread is well defined and remains constant. if there is slope or wind in point ignition fires, the rate of spread of the head fire tends to increase while for linear ignition fires the contrary happens. It is shown that convective effects induced by the fire for steep slope terrain can produce the so-called ‘blow-up’ effect even in the absence of any other special atmospheric conditions. Therefore the definition of rate of spread of a fire and its evaluation from laboratory and field experiments is strongly questioned.
34
Yue, C., P. Ciais, D. Zhu, T. Wang, S. S. Peng und S. L. Piao. „How have past fire disturbances contributed to the current carbon balance of boreal ecosystems?“ Biogeosciences 13, Nr. 3 (04.02.2016): 675–90. http://dx.doi.org/10.5194/bg-13-675-2016.
Der volle Inhalt der QuelleAnnotation:
Abstract. Boreal fires have immediate effects on regional carbon budgets by emitting CO2 into the atmosphere at the time of burning, but they also have legacy effects by initiating a long-term carbon sink during post-fire vegetation recovery. Quantifying these different effects on the current-day pan-boreal (44–84° N) carbon balance and quantifying relative contributions of legacy sinks by past fires is important for understanding and predicting the carbon dynamics in this region. Here we used the global dynamic vegetation model ORCHIDEE–SPITFIRE (Organising Carbon and Hydrology In Dynamic Ecosystems – SPread and InTensity of FIRE) to attribute the contributions by fires in different decades between 1850 and 2009 to the carbon balance of 2000–2009, taking into account the atmospheric CO2 change and climate change since 1850. The fire module of ORCHIDEE–SPITFIRE was turned off for each decade in turn and was also turned off before and after the decade in question in order to model the legacy carbon trajectory by fires in each past decade. We found that, unsurprisingly, fires that occurred in 2000–2009 are a carbon source (−0.17 Pg C yr−1) for the carbon balance of 2000–2009, whereas fires in all decades before 2000 contribute carbon sinks with a collective contribution of 0.23 Pg C yr−1. This leaves a net fire sink effect of 0.06 Pg C yr−1, or 6.3 % of the simulated regional carbon sink (0.95 Pg C yr−1). Further, fires with an age of 10–40 years (i.e., those that occurred during 1960–1999) contribute more than half of the total sink effect of fires. The small net sink effect of fires indicates that current-day fire emissions are roughly balanced out by legacy sinks. The future role of fires in the regional carbon balance remains uncertain and will depend on whether changes in fires and associated carbon emissions will exceed the enhanced sink effects of previous fires, both being strongly affected by global change.
35
Houtman, Rachel M., Claire A. Montgomery, Aaron R. Gagnon, David E. Calkin, Thomas G. Dietterich, Sean McGregor und Mark Crowley. „Allowing a wildfire to burn: estimating the effect on future fire suppression costs“. International Journal of Wildland Fire 22, Nr. 7 (2013): 871. http://dx.doi.org/10.1071/wf12157.
Der volle Inhalt der QuelleAnnotation:
Where a legacy of aggressive wildland fire suppression has left forests in need of fuel reduction, allowing wildland fire to burn may provide fuel treatment benefits, thereby reducing suppression costs from subsequent fires. The least-cost-plus-net-value-change model of wildland fire economics includes benefits of wildfire in a framework for evaluating suppression options. In this study, we estimated one component of that benefit – the expected present value of the reduction in suppression costs for subsequent fires arising from the fuel treatment effect of a current fire. To that end, we employed Monte Carlo methods to generate a set of scenarios for subsequent fire ignition and weather events, which are referred to as sample paths, for a study area in central Oregon. We simulated fire on the landscape over a 100-year time horizon using existing models of fire behaviour, vegetation and fuels development, and suppression effectiveness, and we estimated suppression costs using an existing suppression cost model. Our estimates suggest that the potential cost savings may be substantial. Further research is needed to estimate the full least-cost-plus-net-value-change model. This line of research will extend the set of tools available for developing wildfire management plans for forested landscapes.
36
Benson, Bradley W., Hui L. James und Jung Chul Park. „Heterogeneity in the Effect of Managerial Equity Incentives on Firm Value“. Financial Review 54, Nr. 3 (04.07.2019): 583–638. http://dx.doi.org/10.1111/fire.12185.
Der volle Inhalt der Quelle
37
Price, Owen F., und Ross A. Bradstock. „The effect of fuel age on the spread of fire in sclerophyll forest in the Sydney region of Australia“. International Journal of Wildland Fire 19, Nr. 1 (2010): 35. http://dx.doi.org/10.1071/wf08167.
Der volle Inhalt der QuelleAnnotation:
We investigated the effect of fuel age on the truncation of spread of unplanned fires using a set of 1473 patches in the Sydney region of Australia. Twenty-two percent of patches derived from prescribed fire experienced a subsequent unplanned fire within 5 years, compared with 42% of patches derived from unplanned fires. Among those encounters, the subsequent unplanned fire stopped at the leading edge of 18% of prescribed patches and 11% of unplanned patches. In comparison, the subsequent fire stopped somewhere in the patch for 44% of both prescribed and unplanned fires. Overall, there was a 10% chance that a prescribed burn patch would experience an unplanned fire that stops within the patch. Statistical modelling revealed that the presence of a road barrier was the best predictor of the likelihood of stopping on the leading edge, but fuel age and weather also had an influence. Stopping on the trailing edge was less influenced by the variables analysed. In extreme weather, even 1-year-old patches have a low likelihood of stopping unplanned fires. Fuel age had little influence on the spread of unplanned fires. Consequently, prescribed fires will be most effective when sited at the urban interface where resultant reduced unplanned fire intensity will be a benefit.
38
Kone, Mouhamadou, Kanvaly Dosso, Christine Dakele Yode, Akissi Evelyne Kouakou, Aya Brigitte N'dri, N'Golo Abdoulaye Kone, Julien Kouadio N'dri, Wouter Dekoninck und Sebastien Barot. „Short-term changes in the structure of ant assemblages in a Guinean savanna under differing fire regimes at Lamto Scientific Reserve, Côte d'Ivoire“. Journal of Tropical Ecology 34, Nr. 5 (September 2018): 326–35. http://dx.doi.org/10.1017/s0266467418000305.
Der volle Inhalt der QuelleAnnotation:
Abstract:To maintain savanna vegetation, mid-seasonal fire has been applied since 1961 in the Lamto Savanna (Côte d'Ivoire). However, this prescribed fire has not impeded tree encroachment during recent years, nor have its effects on insect assemblages been documented. Also the impact of tree intrusion on insect assemblages is poorly studied in savanna. To prevent tree density increasing, a change in fire regime might be a solution. In this study, we examined the effect of different fire regimes (early, mid-seasonal and late fires) on leaf-litter ant assemblages in order to suggest appropriate measures for preventing tree invasion without having an effect on insect communities. Sampling was implemented by combining pitfall trapping and leaf-litter sampling before and after three different fire regimes, early, mid-seasonal and late fires. While the ant species richness declined after the passage of early and mid-seasonal fires, significantly more species were found in the burnt savanna after the late fire. However, the losses or gains of species due to different fire regimes did not cause severe changes in the ant species composition. Of the functional groups identified, only the generalists and specialist predators were respectively strongly affected by the early and mid-seasonal fires, certainly due to micro-habitat modification. Based on the trends observed in the present study, we suggest sampling other invertebrate fauna in similar savanna plots to find out if other insect groups have similar reactions to the applied fire regimes.
39
Strydom, Tiaan, Tineke Kraaij, Mark Difford und Richard M. Cowling. „Fire severity effects on resprouting of subtropical dune thicket of the Cape Floristic Region“. PeerJ 8 (10.06.2020): e9240. http://dx.doi.org/10.7717/peerj.9240.
Der volle Inhalt der QuelleAnnotation:
It has been hypothesised that high-intensity fires prevent fire-dependent fynbos from being replaced by fire-avoiding subtropical thicket on dune landscapes of the Cape Floristic Region (CFR). Recent extensive fires provided an opportunity to test this hypothesis. We posit that (1) fire-related thicket shrub mortality would be size dependent, with smaller individuals suffering higher mortality than larger ones; and (2) that survival and resprouting vigour of thicket shrubs would be negatively correlated with fire severity. We assessed survival and resprouting vigour post-fire in relation to fire severity and pre-fire shrub size at two dune landscapes in the CFR. Fire severity was scored at the base of the shrub and categorised into four levels. Pre-fire size was quantified as an index of lignotuber diameter and stem count of each shrub. Resprouting vigour consisted of two variables; resprouting shoot count and resprouting canopy volume. A total of 29 species were surveyed. Post-fire survival of thicket was high (83–85%). We found that smaller shrubs did have a lower probability of post-fire survival than larger individuals but could detect no consistent relationship between shrub mortality and fire severity. Fire severity had a positive effect on resprouting shoot count but a variable effect on resprouting volume. Pre-fire size was positively related to survival and both measures of resprouting vigour. We conclude that thicket is resilient to high-severity fires but may be vulnerable to frequent fires. Prescribed high-intensity fires in dune landscapes are unlikely to reduce the extent of thicket and promote fynbos expansion.
40
Lee, Seoung Soo, George Kablick III, Zhanqing Li, Chang Hoon Jung, Yong-Sang Choi, Junshik Um und Won Jun Choi. „Examination of effects of aerosols on a pyroCb and their dependence on fire intensity and aerosol perturbation“. Atmospheric Chemistry and Physics 20, Nr. 6 (23.03.2020): 3357–71. http://dx.doi.org/10.5194/acp-20-3357-2020.
Der volle Inhalt der QuelleAnnotation:
Abstract. Using a modeling framework, this study investigates how a pyrocumulonimbus (pyroCb) event influences water vapor concentrations and cirrus-cloud properties near the tropopause, specifically focusing on how fire-produced aerosols affect this role. Results from a case study show that when observed fire intensity is high, there is an insignificant impact of fire-produced aerosols on the development of the pyroCb and associated changes in water vapor and cirrus clouds near the tropopause. However, as fire intensity weakens, effects of those aerosols on microphysical variables and processes such as droplet size and autoconversion increase. Due to this, aerosol-induced invigoration of convection is significant for pyroCb with weak-intensity fires and associated weak surface heat fluxes. This leads to a situation where there is a greater aerosol effect on the transport of water vapor to the upper troposphere and the production of cirrus clouds with weak-intensity fires, whereas this effect is muted with strong-intensity fires.
41
Yue, C., P. Ciais, D. Zhu, T. Wang, S. S. Peng und S. L. Piao. „How past fire disturbances have contributed to the current carbon balance of boreal ecosystems?“ Biogeosciences Discussions 12, Nr. 17 (09.09.2015): 14833–67. http://dx.doi.org/10.5194/bgd-12-14833-2015.
Der volle Inhalt der QuelleAnnotation:
Abstract. Boreal fires have immediate effects on regional carbon budgets by emitting CO2 into the atmosphere at the time of burning, but also have legacy effects by initiating a long-term carbon sink during post-fire vegetation recovery. Quantifying these different effects on the current-day pan-boreal (44–84° N) carbon balance and relative contributions of legacy sinks by past fires is important for understanding and predicting the carbon dynamics in this region. Here we used the global dynamic vegetation model ORCHIDEE-SPITFIRE to attribute the contributions by fires in different decades of 1850–2009 to the carbon balance of 2000–2009, taking into account the atmospheric CO2 change and climate change since 1850. The fire module of ORCHIDEE-SPITFIRE was turned off in each decade sequentially, and turned on before and after, to model the legacy carbon trajectory by fires in each past decade. We found that, unsurprisingly, fires that occured in 2000–2009 are a carbon source (−0.17 Pg C yr−1) for the 2000s-decade carbon balance, whereas fires in all decades before 2000 contribute carbon sinks with a collective contribution of 0.23 Pg C yr−1. This leaves a net fire sink effect of 0.06 Pg C yr−1, or 6.3 % of the simulated regional carbon sink (0.95 Pg C yr−1). Further, fires with an age of 10–40 years (i.e. those occurred during 1960–1999) contribute more than half of the total sink effect of fires. The small net sink effect of fires indicates that current-day fire emissions are roughly in balance with legacy sinks. The future role of fires in the regional carbon balance remains uncertain and will depend on whether changes in fires and associated carbon emissions will exceed the enhanced sink effects of previous fires, both being strongly affected by global change.
42
Syphard, Alexandra D., Robert M. Scheller, Brendan C. Ward, Wayne D. Spencer und James R. Strittholt. „Simulating landscape-scale effects of fuels treatments in the Sierra Nevada, California, USA“. International Journal of Wildland Fire 20, Nr. 3 (2011): 364. http://dx.doi.org/10.1071/wf09125.
Der volle Inhalt der QuelleAnnotation:
In many coniferous forests of the western United States, wildland fuel accumulation and projected climate conditions increase the likelihood that fires will become larger and more intense. Fuels treatments and prescribed fire are widely recommended, but there is uncertainty regarding their ability to reduce the severity of subsequent fires at a landscape scale. Our objective was to investigate the interactions among landscape-scale fire regimes, fuels treatments and fire weather in the southern Sierra Nevada, California. We used a spatially dynamic model of wildfire, succession and fuels management to simulate long-term (50 years), broad-scale (across 2.2 × 106 ha) effects of fuels treatments. We simulated thin-from-below treatments followed by prescribed fire under current weather conditions and under more severe weather. Simulated fuels management minimised the mortality of large, old trees, maintained total landscape plant biomass and extended fire rotation, but effects varied based on elevation, type of treatment and fire regime. The simulated area treated had a greater effect than treatment intensity, and effects were strongest where more fires intersected treatments and when simulated weather conditions were more severe. In conclusion, fuels treatments in conifer forests potentially minimise the ecological effects of high-severity fire at a landscape scale provided that 8% of the landscape is treated every 5 years, especially if future fire weather conditions are more severe than those in recent years.
43
Wang, Xianli, Marc-André Parisien, Stephen W. Taylor, Daniel D. B. Perrakis, John Little und Mike D. Flannigan. „Future burn probability in south-central British Columbia“. International Journal of Wildland Fire 25, Nr. 2 (2016): 200. http://dx.doi.org/10.1071/wf15091.
Der volle Inhalt der QuelleAnnotation:
Little is known about how changing climates will affect the processes controlling fire ignition and spread. This study examines the effect of climate change on the factors that drive fire activity in a highly heterogeneous region of south-central British Columbia. Future fire activity was evaluated using Burn-P3, a simulation model used to estimate spatial burn probability (BP) by simulating a very large number of fires. We modified the following factors in the future projections of BP: (1) fuels (vegetation), (2) ignitions (number of fires), and (3) weather (daily conditions and duration of fires). Our results showed that the future climate will increase the number of fires and fire-conducive weather, leading to widespread BP increases. However, the conversion of current forest types to vegetation that is not as flammable may partially counteract the effect of increasing fire weather severity. The top-down factors (ignitions and weather) yield future BPs that are spatially coherent with the current patterns, whereas the changes due to future vegetation are highly divergent from today’s BP. This study provides a framework for assessing the effect of specific agents of change on fire ignition and spread in landscapes with complex fire–climate–vegetation interactions.
44
Caldová, Eva, František Wald und Anna Kuklíková. „Fire Test of Timber-fibre Concrete Composite Floor“. Journal of Structural Fire Engineering 6, Nr. 2 (01.06.2015): 147–54. http://dx.doi.org/10.1260/2040-2317.6.2.147.
Der volle Inhalt der QuelleAnnotation:
The subject of this paper is a description of experimental programme of timber-fibre concrete floor in fire. Furnace test was performed on one full-size floor specimen at the Fire testing laboratory PAVUS. Floor specimen was 4, 5 m long and 3 m wide, consisting of 60 mm fibre concrete topping on plywood formwork, connected to GL beams. It was subjected the standard fire for over 150 min. The membrane effect of the floor was progressively activated and the fire performance of timber-fibre concrete floor was better comparing to traditional design method. The project is a part of the experimental research that deals with the effect of membrane action of composite timber fibre reinforced floor slabs exposed to fire which is based on previous research on steel fibre reinforced concrete slabs. The main objective of the project is the preparation of the analytical model which can predict the fire resistance of such floors with dispersed reinforcement.
45
Becker, Jochen, Josip Medjedovic und Christoph Merkle. „The Effect of CEO Extraversion on Analyst Forecasts: Stereotypes and Similarity Bias“. Financial Review 54, Nr. 1 (06.01.2019): 133–64. http://dx.doi.org/10.1111/fire.12173.
Der volle Inhalt der Quelle
46
Zhou, Kuibin, Naian Liu und Xieshang Yuan. „Effect of Wind on Fire Whirl Over a Line Fire“. Fire Technology 52, Nr. 3 (27.06.2015): 865–75. http://dx.doi.org/10.1007/s10694-015-0507-9.
Der volle Inhalt der Quelle
47
Koo, Joseph H., Peter S. Ng und Fan-Bill Cheung. „Effect of High Temperature Additives in Fire Resistant Materials“. Journal of Fire Sciences 15, Nr. 6 (November 1997): 488–504. http://dx.doi.org/10.1177/073490419701500605.
Der volle Inhalt der QuelleAnnotation:
The effect of high temperature additives in intumescent systems was examined in a laboratory environment. A matrix of ceramic fibers/minerals was incorporated into two intumescent systems. The material performance was determined using a series of small-scale propane-fired furnace tests based on the ASTM E119 time-temperature curve for fire tests of building construction and materials. Several formulations were identified using a 15-minute screening fire test before testing for a longer time period.
48
Chang, Chuan Peng, Shi Wu Huang, Xue Feng Li, Bo Tian und Zi Yi Hou. „A Study of the Capability for Fire Resistance of Polypropylene Fibre Concrete“. Advanced Materials Research 857 (Dezember 2013): 116–23. http://dx.doi.org/10.4028/www.scientific.net/amr.857.116.
Der volle Inhalt der QuelleAnnotation:
The purpose of this paper is to examine the effect of various polypropylene fibre additions (length and content) to concrete on compressive strength and explosive spalling when subjected to high temperatures, which simulate the building or tunnel fires. The experimental results show that the compressive strength of polypropylene fiber concrete (PFC) and plain concrete decreases with increasing temperature. Fibre content in a certain range has a small effect on the compressive strength of the concrete, therefore the polypropylene (PP) fibers has a great influence on the anti-spalling behavior of concrete under fire loading to ensure the integrity of the structure. Keywords: concrete, polypropylene fibre, high temperature, compressive strength, spalling
49
Poulos, Lauren P., und Bitty A. Roy. „Fire and False Brome: How Do Prescribed Fire and Invasive Brachypodium sylvaticum Affect Each Other?“ Invasive Plant Science and Management 8, Nr. 2 (Juni 2015): 122–30. http://dx.doi.org/10.1614/ipsm-d-14-00024.1.
Der volle Inhalt der QuelleAnnotation:
Brachypodium sylvaticum, a shade-tolerant, forest dwelling, and aggressive invasive grass native to Eurasia, is a noxious weed in California, Oregon, and Washington. This species could cause ecosystem collapse by altering forest fire regimes. To examine interactions with fire, we divided two Willamette National Forest sites into eight units and randomly selected half for treatment with prescribed fire in spring 2011. We assessed the effect of B. sylvaticum on fire (severity and intensity) as well as the effect of fire on B. sylvaticum (cover, seedling emergence, and dispersal). We found that B. sylvaticum cover decreased fire severity but had no effect on intensity. Furthermore, fire severity influenced B. sylvaticum cover; in areas receiving low-severity fire, the grass increased from 21 ± 15.05 to 34 ± 15.81%, but in areas of high-severity fire, cover remained consistently around 0% (0 ± 0% cover in yr 1 to 0.2 5± 0.25% in yr 3). In the field, prescribed fire decreased seedling emergence by 32% compared to controls, but not in an associated greenhouse experiment. However, in the greenhouse, severely burned plots had zero emergence, compared to 0.29 ± 0.14 seedlings low-severity m−2 plot. Fire severity also influenced dispersal in the field; we monitored plots with < 0.5% cover B. sylvaticum initially; when these plots experienced low severity fire, they had greater B. sylvaticum cover (increasing 1,200%), suggesting increased dispersal with less severe fires. High-severity dispersal plots did not experience increased cover. High severity fires have the potential to control the grass, but low-severity fires will likely increase its cover.
50
Dupuy, J. L., J. Maréchal, D. Portier und J. C. Valette. „The effects of slope and fuel bed width on laboratory fire behaviour“. International Journal of Wildland Fire 20, Nr. 2 (2011): 272. http://dx.doi.org/10.1071/wf09075.
Der volle Inhalt der QuelleAnnotation:
A set of 109 laboratory fires in Pinus halepensis fuel beds (1 kg m–2) was used to test the effects of slope (0°, 10°, 20°, 30°) and fuel bed width (1, 2, 3 m) on fire behaviour variables such as rate of spread, fuel consumption, flame residence time, temperatures and flame geometry. The qualitative behaviour of the fires is also reported. The 20° and 30° upslope fires are pointed in shape and fire whirls moving along the fire flanks in the direction of the fire head are systematically observed in 30° upslope fires. Flame residence time increases with increasing slope angle, and both slope angle and fuel bed width affect rate of spread. The slope effects observed in 10° and 20° slope angles and in the narrowest fuel beds (1 and 2 m) are similar to those predicted by operational models. However, the observed slope effect at the 30° slope angle is underestimated by these models, in particular in 3 m-wide fuel beds. Flame temperatures correlate closely with dimensionless height and flame lengths correlate closely with fire line intensity. Mechanisms that could explain the different effects observed are suggested and discussed.