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1
Estes, Becky L., Eric E. Knapp, Carl N. Skinner, and Fabian C. C. Uzoh. "Seasonal variation in surface fuel moisture between unthinned and thinned mixed conifer forest, northern California, USA." International Journal of Wildland Fire 21, no. 4 (2012): 428. http://dx.doi.org/10.1071/wf11056.
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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 stands. Sections of logs representing the 1000- and 10 000-h fuel sizes were placed at 72 stations within treatment units in the fall (autumn) of 2007. Following snow-melt in 2008, 10-h fuel sticks were added and all fuels were weighed every 1–2 weeks from May until October. Moisture of the 1000- and 10 000-h fuels peaked at the end of May, and then decreased steadily through the season. Moisture of the 10- and 1000-h fuels did not differ between unthinned and thinned stands at any measurement time. The 10 000-h fuel moisture was significantly less in thinned than unthinned stands only in early to mid-May. Overall, even when fuel moisture varied between treatments, differences were small. The long nearly precipitation-free summers in northern California appear to have a much larger effect on fuel moisture than the amount of canopy cover. Fuel moisture differences resulting from stand thinning would therefore not be expected to substantially influence fire behaviour and effects during times of highest fire danger in this environment.
2
Albini, FA, and ED Reinhardt. "Modeling Ignition and Burning Rate of Large Woody Natural Fuels." International Journal of Wildland Fire 5, no. 2 (1995): 81. http://dx.doi.org/10.1071/wf9950081.
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As part of the development of a model for predicting fuel loading reductions by and intensity histories of fires burning in large woody natural fuels, it was necessary to develop separate models for the processes of ignition and rate of burning of individual fuel elements. This paper describes the derivation of predictive equations for ignition delay time and burning rate (from diameter reduction rate) of large woody natural fuels in a fire environment. The method consists of deriving approximate functional forms using fuel component properties and a measurable ''fire environment temperature'' and then fitting these forms to data taken in laboratory fires using a large propane burner. The equations describe the calibration data with precision adequate for the purpose for which they were designed.
3
Yates, Cameron, Harry MacDermott, Jay Evans, Brett P. Murphy, and Jeremy Russell-Smith. "Seasonal fine fuel and coarse woody debris dynamics in north Australian savannas." International Journal of Wildland Fire 29, no. 12 (2020): 1109. http://dx.doi.org/10.1071/wf20073.
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Several studies have separately explored accumulation of the dominant fuels (grass, fine litter (<6mm diameter) and coarse woody debris (CWD, 6–50mm diameter)) in north Australian savannas. We report an analysis of two longitudinal datasets describing how these three fuel components covary in abundance throughout the year in eucalypt-dominated savanna over a rainfall gradient of 700–1700mm mean annual rainfall (MAR). Our observations concur generally with previous observations that litter accumulation results in a late dry season (LDS) peak in biomass, whereas cured grassy fuels typically are seasonally invariant, and CWD inputs are associated with stochastic severe wet season storms and dry season fires. The distinct LDS litter peak contributes significantly to the potential for LDS fires to be of higher intensity, burn more fuel per unit area and produce greater emissions relative to early dry season (EDS) fires. However, Australia’s current (2018) formal savanna burning emissions avoidance methodology erroneously deems greater EDS fine fuel (grass and fine litter) biomass in four of nine designated vegetation fuel types. The study highlights the need to develop seasonally dynamic modelling approaches that better account for significant seasonal variation in fine fuel inputs and decomposition.
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Daly, RL, and KC Hodgkinson. "Relationships Between Grass, Shrub and Tree Cover on Four Landforms of Semi-Arid Eastern Australia, and Prospects for Change by Burning." Rangeland Journal 18, no. 1 (1996): 104. http://dx.doi.org/10.1071/rj9960104.
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The range of grass, shrub and tree levels present in the Louth region of western New South Wales was determined in an area where woody weeds are considered to be rampant, and the prospects for change by burning were evaluated. Relationships between the three vegetation elements in each of four major landforms were determined by regression and reduction in the canopy cover of woody vegetation after one or two fires were simulated. Basal cover of grass was negatively related to canopy cover of woody vegetation, except in the Sandplains and Dunefields landform. The relationship here was curvilinear with maximum grass cover occurring at 10% canopy cover of the woody vegetation. Pastoralism was considered to become less efficient when the canopy cover of woody vegetation exceeded 5%; 44% of sites measured were below this threshold. The remaining sites could be divided into two groups; one which would fall below the threshold if burnt with a prescribed fire (21%) and the other which required two fires or an equivalent second treatment to reduce the cover below the threshold (35%). The survey confirmed the perception of pastoralists, administrators and scientists that shrub cover is unacceptably high for pastoralism throughout much of the region. Additionally the perennial grass cover was very low and this would increase the instability of forage supply to pastoral herbivores. The high spatial variability in the composition of vegetation indicates that graziers need to identify and treat areas where return on investment in rehabilitation will be highest and most certain.
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Hollis, J. J., W. L. McCaw, and M. G. Cruz. "The effect of woody fuel characteristics on fuel ignition and consumption: a case study from a eucalypt forest in south-west Western Australia." International Journal of Wildland Fire 27, no. 5 (2018): 363. http://dx.doi.org/10.1071/wf17174.
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Coarse woody debris (>0.6 cm in diameter) is an important component of the fuel complex in Australian eucalypt forests, influencing both fire behaviour, smoke production and post-fire ecological processes. We investigated how physical characteristics of woody fuel affected ignition and consumption during an experimental fire where the fuel complex characteristics, fire weather and fire behaviour varied within a narrow range. Decay status, bark condition, arrangement, suspension and extent of charring were classified for 2866 coarse woody fuel particles. We used generalised linear model (GLM) analysis to explain ignition success and the extent of consumption of individual particles, with a focus on larger diameter fuels (>7.5 cm in diameter), which comprised 83% of the woody fuel load and 94% of the woody fuel consumed during the flaming and smouldering stages of combustion. Ignition success was best explained by a model that included fuel arrangement (a surrogate of fuel proximity), suspension and decay status. The extent of fuel consumption was greater for pieces in advanced stages of decay, but suspension (inversely related) and arrangement (directly related) also affected the outcome. Forest management practices, previous fire history and other natural disturbances are likely to influence the distribution of pre-fire diameters and suspension classes that characterise large woody fuels at a site, and will therefore influence woody fuel consumption. This has practical implications for quantifying heat release and atmospheric emissions from fires burning in forests with different management histories.
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Hollis, J. J., W. L. McCaw, and M. G. Cruz. "Corrigendum to: The effect of woody fuel characteristics on fuel ignition and consumption: a case study from a eucalypt forest in south-west Western Australia." International Journal of Wildland Fire 28, no. 8 (2019): 640. http://dx.doi.org/10.1071/wf17174_co.
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Coarse woody debris (>0.6cm in diameter) is an important component of the fuel complex in Australian eucalypt forests, influencing both fire behaviour, smoke production and post-fire ecological processes. We investigated how physical characteristics of woody fuel affected ignition and consumption during an experimental fire where the fuel complex characteristics, fire weather and fire behaviour varied within a narrow range. Decay status, bark condition, arrangement, suspension and extent of charring were classified for 2866 coarse woody fuel particles. We used generalised linear model (GLM) analysis to explain ignition success and the extent of consumption of individual particles, with a focus on larger diameter fuels (>7.5cm in diameter), which comprised 83% of the woody fuel load and 94% of the woody fuel consumed during the flaming and smouldering stages of combustion. Ignition success was best explained by a model that included fuel arrangement (a surrogate of fuel proximity), suspension and decay status. The extent of fuel consumption was greater for pieces in advanced stages of decay, but suspension (inversely related) and arrangement (directly related) also affected the outcome. Forest management practices, previous fire history and other natural disturbances are likely to influence the distribution of pre-fire diameters and suspension classes that characterise large woody fuels at a site, and will therefore influence woody fuel consumption. This has practical implications for quantifying heat release and atmospheric emissions from fires burning in forests with different management histories.
7
Call, PT, and FA Albini. "Aerial and Surface Fuel Consumption in Crown Fires." International Journal of Wildland Fire 7, no. 3 (1997): 259. http://dx.doi.org/10.1071/wf9970259.
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An empirical model is presented which relates fractional reduction in loading to fuel element diameter and moisture content for surface and aerial fuels consumed near the fire front in a spreading crown fire. The model is based upon data from a series of experimental crown fires in immature jack pine. Its intended use is to permit calculation of fuel consumption per unit area (kg/m2) needed to estimate edge intensity (kW/m) from the spread rate of a crown fire. Model predictions of small fuel component fractional loading reduction had a root-mean-square error of almost 0.2 for our calibration data set. Most of the error arises from the model prediction of complete consumption of crown foliage, some of which was not exposed to flame in the fires of our data set. The model does not address the longer term burning of duff and large woody fuels.
8
Santana, Victor M., M. Jaime Baeza, and Rob H. Marrs. "Response of woody and herbaceous fuel to repeated fires in Mediterranean gorse shrublands." International Journal of Wildland Fire 22, no. 4 (2013): 508. http://dx.doi.org/10.1071/wf12036.
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Differences in both species flammability and post-fire regenerative abilities can be the key to understanding fire regimes and vegetation dynamics. We hypothesised that woody species that accumulate the greatest amount of dead fuel and also have fire-stimulated recruitment would benefit when fire occurrence is increased, thus establishing a positive fire–vegetation flammability feedback. To test this hypothesis, we compared successional change over a 25-year period in gorse shrublands that were burnt once and twice. We assessed change in life forms, species traits with respect to the kind of fuel (i.e. woody and herbaceous) and the abundance of standing dead fuel. We found that, at the community level, accumulation of dead fuel was unrelated to recurrent fires because a second fire in the period of maximum fire risk created a community with less dead fuel. This result implies a lack of positive fire–dead fuel accumulation feedback. In contrast, herbaceous species may establish a positive feedback with fire as they were increased by a second fire.
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Roccaforte, John P., Peter Z. Fulé, W. Walker Chancellor, and Daniel C. Laughlin. "Woody debris and tree regeneration dynamics following severe wildfires in Arizona ponderosa pine forests." Canadian Journal of Forest Research 42, no. 3 (March 2012): 593–604. http://dx.doi.org/10.1139/x2012-010.
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Severe forest fires worldwide leave behind large quantities of dead woody debris and regenerating trees that can affect future ecosystem trajectories. We studied a chronosequence of severe fires in Arizona, USA, spanning 1 to 18 years after burning to investigate postfire woody debris and regeneration dynamics. Snag densities varied over time, with predominantly recent snags in recent fires and broken or fallen snags in older fires. Coarse woody debris peaked at > 60 Mg/ha in the time period 6–12 years after fire, a value higher than previously reported in postfire fuel assessments in this region. However, debris loadings on fires older than 12 years were within the range of recommended management values (11.2–44.8 Mg/ha). Overstory and regeneration were most commonly dominated by sprouting deciduous species. Ponderosa pine ( Pinus ponderosa C. Lawson var. scopulorum Engelm.) overstory and regeneration were completely lacking in 50% and 57% of the sites, respectively, indicating that many sites were likely to experience extended periods as shrublands or grasslands rather than returning rapidly to pine forest. More time is needed to see whether these patterns will remain stable, but there are substantial obstacles to pine forest recovery: competition with sprouting species and (or) grasses, lack of seed sources, and the forecast of warmer, drier climatic conditions for coming decades.
10
Stocks, B. J., M. E. Alexander, B. M. Wotton, C. N. Stefner, M. D. Flannigan, S. W. Taylor, N. Lavoie, et al. "Crown fire behaviour in a northern jack pine black spruce forest." Canadian Journal of Forest Research 34, no. 8 (August 1, 2004): 1548–60. http://dx.doi.org/10.1139/x04-054.
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This paper reports on the behaviour of 10 experimental crown fires conducted between 1997 and 2000 during the International Crown Fire Modelling Experiment (ICFME) in Canada's Northwest Territories. The primary goal of ICFME was a replicated series of high-intensity crown fires designed to validate and improve existing theoretical and empirical models of crown fire behaviour. Fire behaviour characteristics were typical for fully developed boreal forest crown fires, with fires advancing at 1570 m/min, consuming significant quantities of fuel (2.85.5 kg/m2) and releasing vast amounts of thermal heat energy. The resulting flame fronts commonly extended 2540 m above the ground with head fire intensities up to 90 000 kW/m. Depth of burn ranged from 1.43.6 cm, representing a 25%65% reduction in the thickness of the forest floor layer. Most of the smaller diameter (<3.0 cm) woody surface fuels were consumed, along with a significant proportion of the larger downed woody material. A high degree of fuel consumption occurred in the understory and overstory canopy with very little material less than 1.0 cm in diameter remaining. The documentation of fire behaviour, fire danger, and fire weather conditions carried out during ICFME permitted the evaluation of several empirically based North American fire behaviour prediction systems and models.
11
Kukavskaya, Elena A., Galina A. Ivanova, Susan G. Conard, Douglas J. McRae, and Valery A. Ivanov. "Biomass dynamics of central Siberian Scots pine forests following surface fires of varying severity." International Journal of Wildland Fire 23, no. 6 (2014): 872. http://dx.doi.org/10.1071/wf13043.
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In 2000–2002 nine 4-ha prescribed fires of various severities were conducted on experimental plots in mature Scots pine forest in the central Siberian taiga, Russia. Total above-ground living biomass decreased after low- and moderate-severity fires by 10 and 15%, whereas high-severity fire reduced living above-ground biomass by 83%. We monitored changes in fuel structure and biomass for 6–8 years following these fires. By 6–8 years after burning the ground fuel loading had recovered to 101, 96 and 82% of pre-fire levels after fires of low-, moderate- and high-severity. Down woody fuel loading increased by 0.18±0.04kgm–2year–1. We developed regressions relating time since fire to changes in above-ground biomass components for fires of different severity for feather moss–lichen Scots pine forest of Siberia. Our results demonstrate the importance of both burn severity and composition of pre-fire surface vegetation in determining rates and patterns of post-fire vegetation recovery on dry Scots pine sites in central Siberia.
12
Stocks, B. J. "Fire Potential in the Spruce Budworm-damaged Forests of Ontario." Forestry Chronicle 63, no. 1 (February 1, 1987): 8–14. http://dx.doi.org/10.5558/tfc63008-1.
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An experimental burning program was carried out in Ontario between 1978 and 1982 to document quantitatively fire behavior in balsam fir killed by spruce budworm. Forest fire potential in budworm-killed balsam fir stands was shown to be significantly higher for a number of years following stand mortality. Crown breakage and windthrow, with resultant fuel complex rearrangement and increased surface fuel loads, peaked 5-8 years after mortality. Fire potential was greatest during this period, decreased gradually as balsam fir surface fuels began to decompose and understory vegetation proliferated. Fires occurring prior to "green-up" in the spring behaved explosively with continuous crowning, high spread rates, and severe problems with downwind spot fires. Summer fires in this fuel type did not spread at all in the early years following mortality; however, sufficient woody surface fuel accumulation 4-5 years after mortality permitted summer fire spread
13
He, Han, Yu Chang, Zhihua Liu, Zaiping Xiong, and Lujia Zhao. "Evaluations on the Consequences of Fire Suppression and the Ecological Effects of Fuel Treatment Scenarios in a Boreal Forest of the Great Xing’an Mountains, China." Forests 14, no. 1 (January 2, 2023): 85. http://dx.doi.org/10.3390/f14010085.
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With global warming, catastrophic forest fires have frequently occurred in recent years, posing a major threat to forest resources and people. How to reduce forest fire risk is a hot topic in forest management. Concerns regarding fire suppression and forest fuel treatments are rising. Few studies have evaluated the ecological effects of fuel treatments. In this study, we used the LANDIS PRO model to simulate the consequences of fire suppression and the ecological effects of fuel treatments in a boreal forest of the Great Xing’an Mountains, China. Four simulation scenarios were designed, focusing on whether to conduct fuel treatments or not under two fire-control policies (current fire suppression policy and no fire suppression policy). Each scenario contains nine fuel treatment plans based on the combinations of different treatment methods (coarse woody debris reduction, prescribed burning, coarse woody debris reduction plus prescribed burning), treatment frequency (low, medium, and high), and treatment area (large, medium, and small). The ecological effects of the fuel treatments were evaluated according to the changes in fire regimes, species succession, and forest landscape patterns to find a forest fuel management plan that is suitable for the Great Xing’an Mountains. The results showed that long-term fire suppression increases fuel loads and the probability of high-intensity forest fires. The nine fuel management plans did not show significant differences in terms of species succession and forest landscape patterns while lowering forest fire intensity, and none of them were able to restore historical vegetation structure and composition. Our results consolidate the foundation for the practical performance of forest fuel treatments in fire-prone forest landscapes. We suggest a suitable fuel treatment plan for the Great Xing’an Mountains, with a low treatment frequency (20 years), large treatment area (10%), and coarse woody debris reduction, plus the prescribed burning measure.
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Mathieu, Renaud, Russell Main, David P. Roy, Laven Naidoo, and 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, no. 3 (June 27, 2019): 37. http://dx.doi.org/10.3390/fire2030037.
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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.
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Smith, Alistair M. S., and Andrew T. Hudak. "Estimating combustion of large downed woody debris from residual white ash." International Journal of Wildland Fire 14, no. 3 (2005): 245. http://dx.doi.org/10.1071/wf05011.
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The production of residual white ash patches within wildfires represents near-complete combustion of the available fuel and releases a considerable quantity of gases to the atmosphere. These patches are generally produced from combustion of large downed woody debris (LDWD) such as fallen trees and snags. However, LDWD are generally ignored in calculations of fuel combusted within environments where surface fires dominate (e.g. southern African savannas). To assess the potential of fractional white ash cover as a remotely sensed measure of LDWD combustion, both the proportion of the surface covered by white ash and the combustion completeness required to produce white ash must be quantified. An aerial photograph of woodland savanna fires in north-western Zimbabwe was analysed to estimate the proportion of white ash cover within a typical satellite sensor pixel. The proportion loss on ignition (LOI) of wood samples from the study area was measured and combined with previous estimates of mean tree biomass. The proportion of white ash within the aerial photographs was 0.2% (± 0.06), which corresponded to an additional 67 320 kg ha−1 of biomass combusted above that typically recorded as combusted from a surface fire in this environment (~7000 kg ha−1). This analysis should be repeated in other savannas and forests, where pre-fire fuel loads and post-fire fractional white ash cover may be higher.
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Hollis, J. J., S. Matthews, R. D. Ottmar, S. J. Prichard, A. Slijepcevic, N. D. Burrows, B. Ward, K. G. Tolhurst, W. R. Anderson, and J. S. Gould. "Testing woody fuel consumption models for application in Australian southern eucalypt forest fires." Forest Ecology and Management 260, no. 6 (August 2010): 948–64. http://dx.doi.org/10.1016/j.foreco.2010.06.007.
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Kukavskaya, Elena A., Evgeny G. Shvetsov, Ludmila V. Buryak, Pavel D. Tretyakov, and Pavel Ya Groisman. "Increasing Fuel Loads, Fire Hazard, and Carbon Emissions from Fires in Central Siberia." Fire 6, no. 2 (February 9, 2023): 63. http://dx.doi.org/10.3390/fire6020063.
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The vast Angara region, with an area of 13.8 million ha, is located in the southern taiga of central Siberia, Russia. This is one of the most disturbed regions by both fire and logging in northern Asia. We have developed surface and ground fuel-load maps by integrating satellite and ground-based data with respect to the forest-growing conditions and the disturbance of the territory by anthropogenic and natural factors (fires and logging). We found that from 2001 to 2020, fuel loads increased by 8% in the study region, mainly due to a large amount of down woody debris at clearcuts and burned sites. The expansion of the disturbed areas in the Angara region resulted in an increase in natural fire hazards in spring and summer. Annual carbon emissions from fires varied from 0.06 to 6.18 Mt, with summer emissions accounting for more than 95% in extreme fire years and 31–68% in the years of low fire activity. While the trend in the increase in annual carbon emissions from fires is not statistically significant due to its high interannual variability and a large disturbance of the study area, there are significantly increasing trends in mean carbon emissions from fires per unit area (p < 0.005) and decadal means (p < 0.1). In addition, we found significant trends in the increase in emissions released by severe fires (p < 0.005) and by fires in wetter, dark, coniferous (spruce, p < 0.005 and Siberian pine, p < 0.025) forests. This indicates deeper burning and loss of legacy carbon that impacts on the carbon cycle resulting in climate feedback.
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Eames, Tom, Jeremy Russell-Smith, Cameron Yates, Andrew Edwards, Roland Vernooij, Natasha Ribeiro, Franziska Steinbruch, and Guido R. van der Werf. "Instantaneous Pre-Fire Biomass and Fuel Load Measurements from Multi-Spectral UAS Mapping in Southern African Savannas." Fire 4, no. 1 (January 14, 2021): 2. http://dx.doi.org/10.3390/fire4010002.
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Landscape fires are substantial sources of (greenhouse) gases and aerosols. Fires in savanna landscapes represent more than half of global fire carbon emissions. Quantifying emissions from fires relies on accurate burned area, fuel load and burning efficiency data. Of these, fuel load remains the source of the largest uncertainty. In this study, we used high spatial resolution images from an Unmanned Aircraft System (UAS) mounted multispectral camera, in combination with meteorological data from the ERA-5 land dataset, to model instantaneous pre-fire above-ground biomass. We constrained our model with ground measurements taken in two locations in savanna-dominated regions in Southern Africa, one low-rainfall region (660 mm year−1) in the North-West District (Ngamiland), Botswana, and one high-rainfall region (940 mm year−1) in Niassa Province (northern Mozambique). We found that for fine surface fuel classes (live grass and dead plant litter), the model was able to reproduce measured Above-Ground Biomass (AGB) (R2 of 0.91 and 0.77 for live grass and total fine fuel, respectively) across both low and high rainfall areas. The model was less successful in representing other classes, e.g., woody debris, but in the regions considered, these are less relevant to biomass burning and make smaller contributions to total AGB.
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Vander Yacht, Andrew L., Patrick D. Keyser, Charles Kwit, Michael C. Stambaugh, Wayne K. Clatterbuck, and Dean M. Simon. "Fuel dynamics during oak woodland and savanna restoration in the Mid-South USA." International Journal of Wildland Fire 28, no. 1 (2019): 70. http://dx.doi.org/10.1071/wf18048.
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Thinning and burning can restore imperilled oak woodlands and savannas in the Southern Appalachian and Central Hardwood regions of the USA, but concomitant effects on fuels are less understood. We monitored (2008 to 2016) fuel load response to replicated combinations of thinning (none, 7, and 14m2ha−1 residual basal area) and seasonal fire (none, March, and October) at three sites. All treatments except burn-only increased total fuel loading. Thinning doubled (+16Mgha−1) 1000-h fuels relative to controls, and three fires in 6 years did not eliminate this difference. Increasing thinning intensity did not consistently enhance the combustion of larger fuels. October fires reduced 100- and 10-h fuels more than March fires. Burning alone reduced leaf litter and 1-h twigs by 30%. Burning after thinning doubled this reduction but increased herbaceous fuels 19-fold. Herbaceous fuels increased at a rate that suggests compensation for losses in woody fine fuels with continued burning. Where fuel reduction is a goal, restoration strategies could be more intentionally designed; however, oak woodlands and savannas are inherently more flammable than closed-canopy forests. Management decisions will ultimately involve weighing the risks associated with increased fuel loads against the benefits of restoring open oak communities.
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Possell, M., M. Jenkins, T. L. Bell, and M. A. Adams. "Emissions from prescribed fires in temperate forest in south-east Australia: implications for carbon accounting." Biogeosciences 12, no. 1 (January 15, 2015): 257–68. http://dx.doi.org/10.5194/bg-12-257-2015.
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Abstract. We estimated emissions of carbon, as equivalent CO2 (CO2e), from planned fires in four sites in a south-eastern Australian forest. Emission estimates were calculated using measurements of fuel load and carbon content of different fuel types, before and after burning, and determination of fuel-specific emission factors. Median estimates of emissions for the four sites ranged from 20 to 139 Mg CO2e ha−1. Variability in estimates was a consequence of different burning efficiencies of each fuel type from the four sites. Higher emissions resulted from more fine fuel (twigs, decomposing matter, near-surface live and leaf litter) or coarse woody debris (CWD; > 25 mm diameter) being consumed. In order to assess the effect of declining information quantity and the inclusion of coarse woody debris when estimating emissions, Monte Carlo simulations were used to create seven scenarios where input parameters values were replaced by probability density functions. Calculation methods were (1) all measured data were constrained between measured maximum and minimum values for each variable; (2) as in (1) except the proportion of carbon within a fuel type was constrained between 0 and 1; (3) as in (2) but losses of mass caused by fire were replaced with burning efficiency factors constrained between 0 and 1; and (4) emissions were calculated using default values in the Australian National Greenhouse Accounts (NGA), National Inventory Report 2011, as appropriate for our sites. Effects of including CWD in calculations were assessed for calculation Method 1, 2 and 3 but not for Method 4 as the NGA does not consider this fuel type. Simulations demonstrate that the probability of estimating true median emissions declines strongly as the amount of information available declines. Including CWD in scenarios increased uncertainty in calculations because CWD is the most variable contributor to fuel load. Inclusion of CWD in scenarios generally increased the amount of carbon lost. We discuss implications of these simulations and how emissions from prescribed burns in temperate Australian forests could be improved.
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Kissing, Lisa B., and Jennifer S. Powers. "Coarse woody debris stocks as a function of forest type and stand age in Costa Rican tropical dry forest: long-lasting legacies of previous land use." Journal of Tropical Ecology 26, no. 4 (May 28, 2010): 467–71. http://dx.doi.org/10.1017/s0266467410000131.
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The ecological importance of trees lasts much longer than their life spans. Standing dead trees (snags) and fallen trunks and branches are an important component of above-ground carbon stocks and nutrient reserves, provide habitat for wildlife, and interact with disturbance regimes (e.g. by serving as fuel for fires) (Clark et al. 2002, Harmon et al. 1986, Pyle et al. 2008). Despite these diverse functions, woody debris stocks remain poorly quantified in tropical forests in general (Brown 1997), and in tropical dry forests in particular (Harmon et al. 1995). More empirical studies of the patterns of woody debris and processes that control its dynamics are needed to understand its role in global biogeochemical cycles and for ecosystem simulation models, many of which do not represent coarse woody debris (CWD) as a separate pool (Cornwell et al. 2009).
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Bowman, DMJS, and PR Minchin. "Environmental Relationships of Woody Vegetation Patterns in the Australian Monsoon Tropics." Australian Journal of Botany 35, no. 2 (1987): 151. http://dx.doi.org/10.1071/bt9870151.
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Indirect gradient analysis was applied to 48 vegetation samples taken from a mosaic of woody vegetation at Berry Springs in the Northern Territory of Australia. Compositional variation among the samples was effectively summarised by a two-dimensional ordination by non-metric multidimensional scaling. Subsequent rotational correlation analysis revealed marked relationships between the vegetation pattern and edaphic variables which reflect two aspects of the moisture regime: water availability during the dry season and the degree of inundation during the wet season. Moisture availability is principally determined by topographic position, through its relationship with soil texture and water table depth. Poor drainage during the wet season appears to separate Melaleuca communities from those dominated by eucalypts. Shrubby and grassy open forests appear to be differentiated by the intensity of the winter drought. The grassy understoreys, which occur on upslope positions well above the water table, die off shortly after the end of the wet season thus providing fuel for fires. A closed Carpentaria forest, located on the slopes above a spring, was found to have relatively organic-rich, fertile, fine-textured soils, possibly reflecting the superior nutrient cycling of the closed forest compared with the frequently burnt surrounding open communities. We suggest that the dense evergreen vegetation presents a barrier to fires from the open communities. This would account for the greater proportion of woody, closed forest species that regenerate exclusively from seed. The fires in the eucalypt forests are of low intensity and plants have vegetative mechanisms to recover from damage. We conclude that the edaphically determined vegetation controls fire regime rather than the converse.
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Hollis, J. J., W. R. Anderson, W. L. McCaw, M. G. Cruz, N. D. Burrows, B. Ward, K. G. Tolhurst, and J. S. Gould. "The effect of fireline intensity on woody fuel consumption in southern Australian eucalypt forest fires." Australian Forestry 74, no. 2 (January 2011): 81–96. http://dx.doi.org/10.1080/00049158.2011.10676350.
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Hollis, J. J., S. Matthews, W. R. Anderson, M. G. Cruz, and N. D. Burrows. "Behind the flaming zone: Predicting woody fuel consumption in eucalypt forest fires in southern Australia." Forest Ecology and Management 261, no. 11 (June 2011): 2049–67. http://dx.doi.org/10.1016/j.foreco.2011.02.031.
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Prichard, Susan J., Eva C. Karau, Roger D. Ottmar, Maureen C. Kennedy, James B. Cronan, Clinton S. Wright, and Robert E. Keane. "Evaluation of the CONSUME and FOFEM fuel consumption models in pine and mixed hardwood forests of the eastern United States." Canadian Journal of Forest Research 44, no. 7 (July 2014): 784–95. http://dx.doi.org/10.1139/cjfr-2013-0499.
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Reliable predictions of fuel consumption are critical in the eastern United States (US), where prescribed burning is frequently applied to forests and air quality is of increasing concern. CONSUME and the First Order Fire Effects Model (FOFEM), predictive models developed to estimate fuel consumption and emissions from wildland fires, have not been systematically evaluated for application in the eastern US using the same validation data set. In this study, we compiled a fuel consumption data set from 54 operational prescribed fires (43 pine and 11 mixed hardwood sites) to assess each model’s uncertainties and application limits. Regions of indifference between measured and predicted values by fuel category and forest type represent the potential error that modelers could incur in estimating fuel consumption by category. Overall, FOFEM predictions have narrower regions of indifference than CONSUME and suggest better correspondence between measured and predicted consumption. However, both models offer reliable predictions of live fuel (shrubs and herbaceous vegetation) and 1 h fine fuels. Results suggest that CONSUME and FOFEM can be improved in their predictive capability for woody fuel, litter, and duff consumption for eastern US forests. Because of their high biomass and potential smoke management problems, refining estimates of litter and duff consumption is of particular importance.
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Gamage, Harshi K., Subrata Mondal, Lynley A. Wallis, Paul Memmott, Darren Martin, Boyd R. Wright, and Susanne Schmidt. "Indigenous and modern biomaterials derived from Triodia (‘spinifex’) grasslands in Australia." Australian Journal of Botany 60, no. 2 (2012): 114. http://dx.doi.org/10.1071/bt11285.
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Plant-derived fibres and resins can provide biomaterials with environmental, health and financial benefits. Australian arid zone grasses have not been explored as sources of modern biomaterials including building materials. Triodia grasslands are a dominant vegetation type in the arid and semiarid regions of Australia covering a third of the continent. Of the 69 identified Triodia species, 26 produce resin from specialised cells in the outer leaf epidermis. In Aboriginal culture, Triodia biomass and resin were valued for their usefulness in cladding shelters and as a hafting agent. Since European settlement, Triodia grasslands have been used for cattle grazing and burning is a common occurrence to improve pasture value and prevent large-scale fires. Although Triodia grasslands are relatively stable to fires, more frequent and large-scale fires impact on other fire sensitive woody and herbaceous species associated with Triodia and invasion of exotic weeds resulting in localised changes in vegetation structure and composition. The extent and change occurring in Triodia grasslands as a result of altered land-use practices, fire regimes, and changing climate warrant careful consideration of their future management. Localised harvesting of Triodia grasslands could have environmental benefits and provide much needed biomaterials for desert living. Research is underway to evaluate the material properties of Triodia biomass and resin in the context of Indigenous and western scientific knowledge. Here, we review uses of Triodia and highlight research needs if sustainable harvesting is to be considered.
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López López, Bernardo, Beatriz Calleja Pelaez, Magdalena Flores-Altamirano, and Cruz Alejandro Rosales Reyes. "Análisis comparativo de cargas de combustible en área afectada por incendio y sin incendio en Malinaltepec, Guerrero." e-CUCBA 10, no. 19 (December 22, 2022): 1–6. http://dx.doi.org/10.32870/ecucba.vi19.257.
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Forest fires are one of the factors that contribute to climate change, among the components that form the fire triangle, fuel is theonly factor that can be manipulated. The objective of this work was to estimate the load of forest fuels in Mg ha-¹ in an area burnedin 2015 and another area without fire. For the evaluation of forest fuel, three sampling sites were established in each of the areas,the woody material was counted by delay time (1, 10, 100 and 1000 h) according to the technique of planar intersections; at the endof each line, litter (h) and mulch (m) were collected in 0.09 m². Tests were carried out to contrast the general fuel load and by typebetween ecosystems; Tukey's means comparison test was used to contrast the fuels in a given area, finally the woody material (ml),mulch (m) and litter (h) were correlated with the total load (ct), litter depth (ph) and mulch depth (ph) using Pearson correlationtests. The total fuel load was 53.10 Mg ha-¹ in the burned area, while the area without fire showed a load of 27.26 Mg ha-¹ withoutsignificant differences (p = 0.114). On the comparison of loads by delay time, the fuel of 1, 10 and 100 h showed a higher load inthe burned area, although it was not significant (p > 0.05); the analysis by component showed a higher litter load in the non-burnedarea with 12.90 Mg ha-¹ (p = 0.015) and the woody material was statistically higher in the burned area with 35.95 Mg ha-¹ (p =0.024). The correlation of variables showed an r = 0.95 between the woody material and the total load; followed by leaf litter andmulch (r = 0.80); on the contrary, the total load in the non-burned area showed a correlation with the mulch and leaf litter (r = 0.89and 0.83). The forest fire contributed to the reduction of litter and mulch but maximized the load of woody fuel.
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Knapp, Eric E., and Jon E. Keeley. "Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest." International Journal of Wildland Fire 15, no. 1 (2006): 37. http://dx.doi.org/10.1071/wf04068.
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Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.
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Roos, Christopher I., Thomas W. Swetnam, T. J. Ferguson, Matthew J. Liebmann, Rachel A. Loehman, John R. Welch, Ellis Q. Margolis, et al. "Native American fire management at an ancient wildland–urban interface in the Southwest United States." Proceedings of the National Academy of Sciences 118, no. 4 (January 19, 2021): e2018733118. http://dx.doi.org/10.1073/pnas.2018733118.
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The intersection of expanding human development and wildland landscapes—the “wildland–urban interface” or WUI—is one of the most vexing contexts for fire management because it involves complex interacting systems of people and nature. Here, we document the dynamism and stability of an ancient WUI that was apparently sustainable for more than 500 y. We combine ethnography, archaeology, paleoecology, and ecological modeling to infer intensive wood and fire use by Native American ancestors of Jemez Pueblo and the consequences on fire size, fire–climate relationships, and fire intensity. Initial settlement of northern New Mexico by Jemez farmers increased fire activity within an already dynamic landscape that experienced frequent fires. Wood harvesting for domestic fuel and architectural uses and abundant, small, patchy fires created a landscape that burned often but only rarely burned extensively. Depopulation of the forested landscape due to Spanish colonial impacts resulted in a rebound of fuels accompanied by the return of widely spreading, frequent surface fires. The sequence of more than 500 y of perennial small fires and wood collecting followed by frequent “free-range” wildland surface fires made the landscape resistant to extreme fire behavior, even when climate was conducive and surface fires were large. The ancient Jemez WUI offers an alternative model for fire management in modern WUI in the western United States, and possibly other settings where local management of woody fuels through use (domestic wood collecting) coupled with small prescribed fires may make these communities both self-reliant and more resilient to wildfire hazards.
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Saura-Mas, S., S. Paula, J. G. Pausas, and F. Lloret. "Fuel loading and flammability in the Mediterranean Basin woody species with different post-fire regenerative strategies." International Journal of Wildland Fire 19, no. 6 (2010): 783. http://dx.doi.org/10.1071/wf09066.
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The flammability and combustibility of plant communities are determined by species features related to growth-form, structure and physiology. In some ecosystems, such as the Mediterranean ones, these characteristics may contribute to the existence of fire-prone species. We measured several parameters associated with the flammability and fuel loading of dominant woody species with different post-fire regenerative strategies (seeders and non-seeders) in shrublands in the western Mediterranean Basin. Overall, seeder species show lower fuel load but are more prone to burning owing to a higher dead-to-live fuel ratio, live fine-fuel proportion and dead fine-fuel proportion. Moreover, they burst into flame at lower temperatures than non-seeders. In the Mediterranean Basin, most seeder species emerged mainly during the Quaternary, under a highly fluctuating Mediterranean climate and during recurrent fires. We propose that properties related to the combustibility and flammability of seeders may be the result of selective pressures associated with both fire and climate. These results suggest that ecosystems dominated by seeder species are more susceptible to fire risk than those dominated by non-seeder species in the Mediterranean Basin. Therefore, the proportion of these types of species resulting from previous fire or management history is likely to determine the characteristics of future fire events.
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Carcaillet, Christopher, Greger Hörnberg, and Olle Zackrisson. "Woody vegetation, fuel and fire track the melting of the Scandinavian ice-sheet before 9500 cal yr BP." Quaternary Research 78, no. 3 (August 27, 2012): 540–48. http://dx.doi.org/10.1016/j.yqres.2012.08.001.
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AbstractNew studies indicate the presence of early Holocene ice-free areas far north in Scandinavia. Post-glacial fire and vegetation were investigated based on sedimentary charcoal and pollen from two small lakes in northern Sweden. Accumulation of organic sediment started around 10,900 and 9200 cal yr BP, showing that both lake valleys were ice-free extremely early given their northerly location. Fire events started after 9600 cal yr BP and became less common around the ‘8.2-ka event’. Woody vegetation provided fuel that contributed to fires. The first vegetation in our pollen record consisted of Hippophae, Dryas, grasses and sedges. Subsequently broadleaved trees (Betula, Salix) increased in abundance and later Pinus, Alnus, ferns and Lycopodium characterized the vegetation. Pollen from Larix, Picea and Malus were also found. The change in vegetation composition was synchronous with the decrease in lake-water pH in the region, indicating ecosystem-scale processes; this occurred during a period of net global and regional warming. The changes in fire frequency and vegetation appear independent of regional trends in precipitation. The reconstructed fire history and vegetation support the scenario of early ice-free areas far north in Scandinavia during early Holocene warming, creating favorable conditions for woody plants and wildfires.
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Davies, Kirk W., Chad S. Boyd, Jon D. Bates, and April Hulet. "Dormant season grazing may decrease wildfire probability by increasing fuel moisture and reducing fuel amount and continuity." International Journal of Wildland Fire 24, no. 6 (2015): 849. http://dx.doi.org/10.1071/wf14209.
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Mega-fires and unprecedented expenditures on fire suppression over the past decade have resulted in a renewed focus on presuppression management. Dormant season grazing may be a treatment to reduce fuels in rangeland, but its effects have not been evaluated. In the present study, we evaluated the effect of dormant season grazing (winter grazing in this ecosystem) by cattle on fuel characteristics in sagebrush (Artemisia L.) communities at five sites in south-eastern Oregon. Winter grazing reduced herbaceous fuel cover, continuity, height and biomass without increasing exotic annual grass biomass or reducing bunchgrass basal area or production. Fuel moisture in winter-grazed areas was high enough that burning was unlikely until late August; in contrast, fuels in ungrazed areas were dry enough to burn in late June. Fuel biomass on perennial bunchgrasses was decreased by 60% with winter grazing, which may reduce the potential for fire-induced mortality. The cumulative effect of winter grazing from altering multiple fuel characteristics may reduce the likelihood of fire and the potential severity in sagebrush communities with an understorey dominated by herbaceous perennials. Dormant season grazing has the potential to reduce wildfire suppression expenditures in many rangelands where herbaceous fuels are an issue; however, increasing woody vegetation and extreme fire weather may limit its influence.
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Carvalho, Karine S., Ane Alencar, Jennifer Balch, and Paulo Moutinho. "Leafcutter Ant Nests Inhibit Low-Intensity Fire Spread in the Understory of Transitional Forests at the Amazon's Forest-Savanna Boundary." Psyche: A Journal of Entomology 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/780713.
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Leaf-cutter ants (Attaspp.) remove leaf litter and woody debris—potential fuels—in and around their nests and foraging trails. We conducted single and three annual experimental fires to determine the effects of this leaf-cutter ant activity on the behavior of low-intensity, slow-moving fires. In a transitional forest, where the southern Amazon forest meets the Brazilian savanna, we tested whether leaf-cutter ant nests and trails (i) inhibit fire spread due to a lack of fuels, and (ii), thereby, reduce the total burned area during these experimental low-intensity fires, particularly at forest edges where leaf-cutter ant abundance was higher. Fine-medium fuel mass increased with an increase in distance from ant nest, and the mean area of bare soil was greater on nests than on the forest floor. Between 60 to 90 percent of the unburned area was within 30 m of ant nests, and burned area significantly increased with increasing distance to ant nests. In addition, the number of ant nests declined with increasing distance from the forest edge, and, with exception of the first experimental fire, burned area also increased with increasing distance from the edge. The present study provides new insight to fire ecology in Amazon environments.
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Nizkiy, Sergei, and Aleksei Muratov. "On the issue of involving abandoned agricultural land in crop rotation." E3S Web of Conferences 203 (2020): 02005. http://dx.doi.org/10.1051/e3sconf/202020302005.
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In the nineties of the last century due to the known economic stress experienced in this time in Russia there were more than fifty million hectors of arable lands withdrawn from the Russian agricultural turnover. There are more than one million hectors of such arable deserted lands in the Amur Region of the Russian Federation (The Far Eastern part of Russia). These arable lands have turned into deteriorating lands in abeyance being colonized by weeds and periodically attacked by fires. As a result of this, these promising agricultural lands, being used for the food supply and forage resources production, have lost their primary purpose of use. It has become a serious national economic problem. Nowadays there is a gradual inclusion of such arable lands into soya and wheat production. The conduction of agrochemical and geo-botanical research needed for suitability evaluation of such arable lands for soya and wheat species cultivation is to a certain degree very expensive and time-consuming procedure. Our research work suggests implementing resources-evaluating method which implies one-time route study in the period of mass flowering of plants and identifying the plants of the arable lands that have resource value. If the number of these plants exceeds eighty percent in relation to the whole species composition, then such arable lands are considered to be suitable for crop rotation. If this ratio is less than sixty percent, then it is necessary to take extra measures in order to reduce the number of weeds and woody plants on such arable lands.
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Burrows, Neil D. "Fire dependency of a rock-outcrop plant Calothamnus rupestris (Myrtaceae) and implications for managing fire in south-western Australian forests." Australian Journal of Botany 61, no. 2 (2013): 81. http://dx.doi.org/10.1071/bt12240.
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Granite outcrops embedded in south-western Australian forests provide habitat for unique biotic assemblages and refugia for fire-sensitive taxa. Discontinuous vegetation and natural barriers to fire spread enable outcrops to function as fire refugia, provided fires in the surrounding forest are not of high intensity. In Summer 2003, lightning started a fire in jarrah forest that had not been burnt for almost 20 years. The high-intensity fire burned the vegetation on Mount Cooke, a large granite outcrop, providing an opportunity to study the response of Calothamnus rupestris Schauer, a fire-sensitive serotinous plant. The population was killed by the fire, but readily regenerated from seed stored in woody capsules. The post-fire population reached maturity after ~7.5 years, whereas the seed bank is unlikely to recover to the pre-fire level until ~14 years. The likelihood of intense forest wildfires affecting outcrop communities can be reduced by frequent low-intensity prescribed burning in the surrounding forests to reduce fuel hazard and quantity. Low-intensity forest fires are unlikely to be lethal to sensitive granite-outcrop communities.
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Schiks, T. J., B. M. Wotton, M. R. Turetsky, and B. W. Benscoter. "Variation in fuel structure of boreal fens." Canadian Journal of Forest Research 46, no. 5 (May 2016): 683–95. http://dx.doi.org/10.1139/cjfr-2015-0445.
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Wildfire frequency and severity in boreal peatlands can be limited by wet fuel conditions, but increases in burn severity can occur when lower water table positions cause drying of fuels. To date, most studies on northern peatland fires have focused on ombrotrophic bogs. Though minerotrophic fens are the most common type of peatland in North America, the influence of fuel structure and loading on potential fire behaviour in boreal fens is poorly understood. To investigate the potential for widespread flame front propagation across boreal fens, we quantified the fuel components present in three generalized boreal fen types (open, shrub, and treed fens) in northern Alberta, Canada. The loadings of aerial fuels, tall shrubs, and downed woody debris varied significantly among fen types. Fuel loads tended to be smallest in the open fens and largest in the treed fens. Open and shrub fens had larger loads of total surface fuels relative to treed fens, with short-statured shrubs being the dominant contributor to surface fuel load. Based on our observations of available fuel loads, each of the fen types may support moderate- to high-intensity fire following long-term drying, which may not only consume some fraction of the aboveground biomass, but also provide a substantial downward pulse of energy to initiate smouldering in the organic layer.
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Henning, Sandra J., and Donald I. Dickmann. "Vegetative Responses to Prescribed Burning in a Mature Red Pine Stand." Northern Journal of Applied Forestry 13, no. 3 (September 1, 1996): 140–46. http://dx.doi.org/10.1093/njaf/13.3.140.
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Abstract We investigated the effects of low-intensity, prescribed spring surface fires at varying intervals in a widely spaced, mature red pine plantation growing on a high quality sandy loam soil in northern Lower Michigan. Measurements of overstory characteristics, as well as the composition and development of the herbaceous and woody understory, were taken in unburned plots and during the seventh growing season following a single burn, the second growing season following the last of two burns at 5 yr intervals, and the growing season immediately following the last of four burns 2 yr intervals. Except for loss of a few trees due to crown scorch early in the study when fuel loadings were high, the red pine overstory was minimally affected by fires at any return interval. Compared to unburned plots, fire had no effect on total species richness or percent cover of ground flora < 1.4 m tall, but species composition shifted; cover of mosses and lichens declined and black cherry seedlings increased at the two shortest fire intervals. Although percent cover of grasses, bracken fern, and Rubus spp. appeared to increase following fire, the clumped distribution of vegetation and interplot variability in overstory density obscured the statistical significance of these trends. Species richness and density of stems in the woody understory (> 1.4 m tall but < 10 cm dbh) declined abruptly as burning interval decreased and number of burns increased. Fewer than two woody understory species, on the average, persisted on plots burned every 2 yr, whereas nearly 12 grew on unburned plots. Postburn conditions were conducive to the re-establishment of black cherry and paper birch in the understory; density of all other major species dropped sharply after more than one fire. As time after the last fire increased, however, red maple, choke cherry, and white ash densities began to recover slowly, largely by sprouting. The significance of these findings to red pine managers in the Lake States is discussed. North. J. Appl. For. 13(3):140-146.
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Peterson, Kate F., Bianca N. I. Eskelson, Vicente J. Monleon, and Lori D. Daniels. "Surface fuel loads following a coastal–transitional fire of unprecedented severity: Boulder Creek fire case study." Canadian Journal of Forest Research 49, no. 8 (August 2019): 925–32. http://dx.doi.org/10.1139/cjfr-2018-0510.
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British Columbia experienced three years with notably large and severe wildfires since 2015. Multiple stand-replacing wildfires occurred in coastal–transitional forests, where large fires are typically rare, and thus, information on post-fire carbon is lacking. Because of their carbon storage potential, coastal–transitional forests are important in the global carbon cycle. We examined differences in surface fuel carbon among fire severity classes in 2016, one year after the Boulder Creek fire, which burned 6 735 ha of coastal–transitional forests in 2015. Using remotely sensed indices (dNBR), we partitioned the fire area into unburned (control), low-, moderate-, and high-severity classes. Field plots were randomly located in each class. At each plot, surface fuel carbon was quantified by type, namely coarse, small, and fine woody material, duff, and litter, and carbon mass by fuel type was compared among severity classes. Total surface fuel carbon did not differ significantly between burned and unburned plots; however, there was significantly less duff and litter carbon in burned plots. Remotely sensed severity classes did not properly capture wildfire impacts on surface fuels, especially at lower severities. Pre-fire stand characteristics are also important drivers of surface fuel loads. This case study provides baseline data for examining post-fire fuel carbon dynamics in coastal–transitional British Columbia.
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Hudak, Andrew T., Roger D. Ottmar, Robert E. Vihnanek, Nolan W. Brewer, Alistair M. S. Smith, and Penelope Morgan. "The relationship of post-fire white ash cover to surface fuel consumption." International Journal of Wildland Fire 22, no. 6 (2013): 780. http://dx.doi.org/10.1071/wf12150.
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White ash results from the complete combustion of surface fuels, making it a logically simple retrospective indicator of surface fuel consumption. However, the strength of this relationship has been neither tested nor adequately demonstrated with field measurements. We measured surface fuel loads and cover fractions of white ash and four other surface materials (green vegetation, brown non-photosynthetic vegetation, black char and mineral soil) immediately before and after eight prescribed fires in four disparate fuelbed types: boreal forest floor, mixed conifer woody slash, mixed conifer understorey and longleaf pine understorey. We hypothesised that increased white ash cover should correlate significantly to surface fuel consumption. To test this hypothesis, we correlated field measures of surface fuel consumption with field measures of surface cover change. Across all four fuelbed types, we found increased white ash cover to be the only measure of surface cover change that correlated significantly to surface fuel consumption, supporting our hypothesis. We conclude that white ash load calculated from immediate post-fire measurements of white ash cover, depth and density may provide an even more accurate proxy for surface fuel consumption, and furthermore a more physically based indicator of fire severity that could be incorporated into rapid response, retrospective wildfire assessments.
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Hosegood, Steven, Mathew Leitch, Chander Shahi, and Reino Pulkki. "Moisture and energy content of fire-burnt trees for bioenergy production: A case study of four tree species from northwestern Ontario." Forestry Chronicle 87, no. 1 (February 1, 2011): 42–47. http://dx.doi.org/10.5558/tfc87042-1.
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With the current energy reform, the Ontario government has taken an initiative to phase out coal-fired generatingstations by 2014, and replace coal with biomass as feedstock at the Atikokan Generating Station. This switch to greenenergy production has opened a new avenue of income for mills and biomass-harvesting companies. However, as theneed for biomass increases, harvesting residues may no longer satisfy the needs of cogeneration facilities and new sourcesmay be sought. A potential source of woody biomass in Ontario is from forest fires. On average, an area of 35 460 ha or3 868 034 m3 of wood is devastated by wildfire every year in the Area of the Undertaking in Ontario and has the potentialto be salvaged. However, the fuel quality and feasibility of salvaging wildfire-burnt areas for bioenergy production innorthern Ontario has not been investigated so far. In this study, five different-aged fires in the MNR Thunder Bay District—12, 18, 24, 37, and 52 months old—were sampled for moisture content and calorific value of the wood. This samplingwas done across four of the most prolific tree species grown in northwestern Ontario—white birch, trembling aspen,balsam fir, and black spruce. The average moisture content (dry weight basis) of the five fires ranged from 27.1% to 34.9%and the average calorific value from 19.0 MJ/kg to 21.1 MJ/kg. Significant differences in moisture content were foundbetween the species and the ages of fire. Hardwood species had significantly higher moisture content compared to softwoods.The results display that wildfire-burnt areas have the potential to supply good-quality fuel for bioenergy productionin northwestern Ontario. Key words: biomass, wildfire-burnt areas, bioenergy production, moisture content, calorific value, northern Ontario
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Price, Jodi N., and John W. Morgan. "Multi-decadal increases in shrub abundance in non-riverine red gum (Eucalyptus camaldulensis) woodlands occur during a period of complex land-use history." Australian Journal of Botany 57, no. 3 (2009): 163. http://dx.doi.org/10.1071/bt07079.
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The history of land-use was examined in Eucalyptus camaldulensis Dehnh. woodland in the Victoria Valley of the Grampians National Park, south-eastern Australia, to help interpret changes in vegetation there during the last 50 years. We used aerial photography and dendrochronological data to quantify the amount of, and the rate of change in, the woody-vegetation cover between 1948 and 1997, and historical data to document land-use changes during this time. Aerial photographs indicated that in 1948, 56% of study area had <50% cover of woody plants. By 1997, 90% of the study area had >50% woody-plant cover. The native shrub Leptospermum scoparium J.R. Forst & G. Forst (Myrtaceae) was predominantly responsible for the increases in cover. Demographic analyses indicated that recruitment has been ongoing rather than episodic; large numbers of shrubs, however, have recruited since 1994. We hypothesise that the vegetation changes observed are likely a response to changes in land-use that have occurred since European occupation. Increased woody-plant cover followed the removal of sheep grazing in the long-term absence of fire. It is very likely that the long history of stock grazing, coupled with selective logging and associated soil disturbance, initiated a change in understorey vegetation by reducing competitive native tussock grasses and fuel loads to carry fires and this reduction was initially responsible for the encroachment of shrubs into the woodland. Recruitment has been ongoing in the absence of any recent land-use changes (most utilisation ceasing after the declaration of National Park status in 1984) and hence, this transformation from species-rich herbaceous woodland to shrubby woodland is expected to continue in the future.
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Kirkpatrick, Jamie B., and Ian Jenkinson. "Effects of Increasing Fire Frequency on Conservation Values in Eucalyptus Grassy Woodland in the Process of Invasion by Allocasuarina verticillata." Fire 5, no. 2 (February 25, 2022): 31. http://dx.doi.org/10.3390/fire5020031.
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Woody thickening is a widespread phenomenon in the grassy woodlands of the world, often with deleterious effects on nature conservation values. We aimed to determine whether increasing the frequency of planned fire prevented woody thickening and improved conservation values in a Eucalyptus viminalis grassy woodland in the process of invasion by Allocasuarina verticillata (henceforth Allocasuarina) in Hobart, Tasmania, Australia. We used a before–after control intervention design. Ten plots from which detailed vegetation data were collected in 2018 (before the burns), 2019 (between burns), 2020 (between burns) and 2021 (after the burns) were randomly located in each of four blocks. Two of the blocks were burned in both 2018 and 2021. One block was burned only in 2021, and another was not burned at all. Mechanical thinning of Allocasuarina took place in 2021 in six plots in one unburned block and in three twice-burned plots. The fires were low intensity and patchy, reflecting the reality of planned burns in this environment. Thus, there were unburned plots mixed with burned plots in each of the three burned blocks. We compared changes in vegetation and cover attributes between a preburn survey in 2018 and a postburn survey in 2021, between five fire history/thinning classes (unburned, no thinning; unburned, thinning; twice burned; burned in 2018 only; burned in 2021 only). Fires in both 2018 and 2021 resulted in lower litter cover and higher exotic species richness than one fire in 2021. Exotic species richness increase between 2018 and 2021 was greater after fires in 2018 and 2021 than after a fire in 2021 alone. Exotic species richness was lowest six years after fire and highest one to three years after fire. The basal area of Allocasuarina was, counter-intuitively, less reduced by two fires in four years than by one. Mechanical thinning reduced shrub layer cover, which largely consisted of small trees, but did not affect basal area. Our data suggested that grass cover increased until five years after a fire, declining back to a low level by eight years. The implications of the results for conservation management are that the mechanical removal of young Allocasuarina may be successful in preventing its thickening and that burning at a five-year interval is likely to best maintain understorey conservation values. The counter-intuitive results related to Allocasuarina basal area emphasise the importance of understanding cumulative effects of fire regimes on fuel cycles and the consequent effects on tree mortality.
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Alhaj-Khalaf, Mhd Wathek. "Improved forest fire spread mapping by developing custom fire fuel models in replanted forests in Hyrcanian forests, Iran." Forest Systems 30, no. 2 (August 2021): e008-e008. http://dx.doi.org/10.5424/fs/2021302-17980.
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Aim of the study: Forest fuel classification and characterization is a critical factor in wildfire management. The main purpose of this study was to develop custom fuel models for accurately mapping wildfire spread compared to standard models. Area of study: The study was conducted at a replanted forest dominated by coniferous species, in the Arabdagh region, Golestan Province, northern Iran. Material and methods: Six custom fuel models were developed to characterize the main vegetation types in the study area. Fuel samples were collected from 49 randomly selected plots. In each plot, the fuel load of 1-hr, 10-hr, 100-hr, 1000-hr, live herbs, live woody plants, surface area volume ratio, and fuel depth were estimated using the Fuel Load (FL) sampling method along three transects. Canopy fuel load was calculated for each fuel model. The performance of the custom fuel models versus standard fuel models on wildfire behavior simulations was compared using the FlamMap MTT simulator. Main results: The results showed that, despite the similarity in the burned area between observed and modeled fires, the custom fuel models produced an increase in simulation accuracy. Compared to the observed fire, simulation results did not give realistic results to the crown fire. The simulation using standard fuel models did not result in crown fire, while the simulation using custom fuel models showed a moderate rate of crown fire with a Kappa coefficient of 0.54. Research highlights: The results demonstrated the importance of developing custom fuel models to simulate wildfire maps with higher accuracy for wildfire risk management.
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Bergmeier, Erwin, Jorge Capelo, Romeo Di Pietro, Riccardo Guarino, Ali Kavgacı, Javier Loidi, Ioannis Tsiripidis, and Fotios Xystrakis. "‘Back to the Future’—Oak wood-pasture for wildfire prevention in the Mediterranean." Plant Sociology 58, no. 2 (December 31, 2021): 41–48. http://dx.doi.org/10.3897/pls2021582/04.
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In the summer of 2021, enormous wildfires in the Mediterranean eliminated huge areas of mainly coniferous forest, destroyed adjacent settlements and claimed the lives of many people. The fires indicate effects of climate change and expose consequences of rural demographic changes, deficits in regional and touristic development planning and shortcomings in forest policy. This forum article highlights the dimensions of the problem, calls for a paradigm shift and shows solutions. Land abandonment, woody plant encroachment and non-reflective afforestation are leading to increasing amounts of combustible biomass. To prevent disastrous fires in future, fundamental changes in tree species composition, forest structure and management are essential. Plantations of reseeding pines are to be substituted by spacious or periodically open woodlands of long-lived trees with resprouting capacity such as Mediterranean oaks. Biomass-reducing practices including wood-pasture have to be revived in rural and peri-urban areas. Exemplary fire-resistant multifunctional oak woodlands occur throughout the Mediterranean. Urgent and medium-term measures in the burnt areas include promoting natural ecosystem regeneration, developing regionalized seed banks and nurseries to support native genetic resources, fostering vegetation mosaics of groves and multiple-use open and coppice woodland maintained by traditional practices, and in general forest management aiming at fuel biomass reduction and a policy counteracting land abandonment.
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Whitburn, Simon, Martin Van Damme, Lieven Clarisse, Daniel Hurtmans, Cathy Clerbaux, and Pierre-François Coheur. "IASI-derived NH<sub>3</sub> enhancement ratios relative to CO for the tropical biomass burning regions." Atmospheric Chemistry and Physics 17, no. 19 (October 13, 2017): 12239–52. http://dx.doi.org/10.5194/acp-17-12239-2017.
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Abstract. Vegetation fires are a major source of ammonia (NH3) in the atmosphere. Their emissions are mainly estimated using bottom-up approaches that rely on uncertain emission factors. In this study, we derive new biome-specific NH3 enhancement ratios relative to carbon monoxide (CO), ERNH3 ∕ CO (directly related to the emission factors), from the measurements of the IASI sounder onboard the Metop-A satellite. This is achieved for large tropical regions and for an 8-year period (2008–2015). We find substantial differences in the ERNH3 ∕ CO ratios between the biomes studied, with calculated values ranging from 7 × 10−3 to 23 × 10−3. For evergreen broadleaf forest these are typically 50–75 % higher than for woody savanna and savanna biomes. This variability is attributed to differences in fuel types and size and is in line with previous studies. The analysis of the spatial and temporal distribution of the ERNH3 ∕ CO ratio also reveals a (sometimes large) within-biome variability. On a regional level, woody savanna shows, for example, a mean ERNH3 ∕ CO ratio for the region of Africa south of the Equator that is 40–75 % lower than in the other five regions studied, probably reflecting regional differences in fuel type and burning conditions. The same variability is also observed on a yearly basis, with a peak in the ERNH3 ∕ CO ratio observed for the year 2010 for all biomes. These results highlight the need for the development of dynamic emission factors that take into better account local variations in fuel type and fire conditions. We also compare the IASI-derived ERNH3 ∕ CO ratio with values reported in the literature, usually calculated from ground-based or airborne measurements. We find general good agreement in the referenced ERNH3 ∕ CO ratio except for cropland, for which the ERNH3 ∕ CO ratio shows an underestimation of about 2–2.5 times.
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Kennedy, Maureen C., Susan J. Prichard, Donald McKenzie, and Nancy H. F. French. "Quantifying how sources of uncertainty in combustible biomass propagate to prediction of wildland fire emissions." International Journal of Wildland Fire 29, no. 9 (2020): 793. http://dx.doi.org/10.1071/wf19160.
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Smoke emissions from wildland fires contribute to concentrations of atmospheric particulate matter and greenhouse gases, influencing public health and climate. Prediction of emissions is critical for smoke management to mitigate the effects on visibility and air quality. Models that predict emissions require estimates of the amount of combustible biomass. When measurements are unavailable, fuel maps may be used to define the inputs for models. Mapped products are based on averages that poorly represent the inherent variability of wildland fuels, but that variability is an important source of uncertainty in predicting emissions. We evaluated the sensitivity of emissions estimates to wildland fuel biomass variability using two models commonly used to predict emissions: Consume and the First Order Fire Effects Model (FOFEM). Flaming emissions were consistently most sensitive to litter loading (Sobol index 0.426–0.742). Smouldering emissions were most often sensitive to duff loading (Sobol 0.655–0.704) under the extreme environmental scenario. Under the moderate environmental scenario, FOFEM-predicted smouldering emissions were similarly sensitive to sound and rotten coarse woody debris (CWD) and duff fuel components (Sobol 0.193–0.376). High variability in loading propagated to wide prediction intervals for emissions. Direct measurements of litter, duff and coarse wood should be prioritised to reduce overall uncertainty.
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Drewa, Paul B. "Effects of fire season and intensity on Prosopis glandulosa Torr. var. glandulosa." International Journal of Wildland Fire 12, no. 2 (2003): 147. http://dx.doi.org/10.1071/wf02021.
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In pyrogenic ecosystems, responses of resprouting woody vegetation may depend more on fire season than on intensity. I explored this hypothesis by examining fire season and intensity effects on response of Prosopis glandulosa, a resprouting shrub in Chihuahuan desert grasslands of the south-western United States. Clipping as well as low and high intensity fires (natural and added fuels, respectively) were applied during the 1999 growing season and the 2000 dormant season. Both fire season and intensity affected shrub responses. Numbers of resprouts increased 16%, and heights increased 8% after dormant season versus growing season treatments of fire and clipping combined. Height and resprout number decreased with increased fire intensity. Fire season and intensity effects on canopy area and stem growth were generally not detected. My results do not support the above hypothesis. Instead, fire season and intensity influence shrub responses in different ways via different mechanisms. Prosopis glandulosa has the potential to respond more after dormant season than growing season fires, perhaps as determined by carbohydrate availability in underground organs at the time of fire. However, realization of this potential is contingent on fire intensity as influenced primarily by fuel amount. In turn, fire intensity will determine the amount and duration of heat penetration into soils and thus the amount of damage to growing points of under-ground organs.
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Silcock, J. L., G. B. Witt, and R. J. Fensham. "A 150-year fire history of mulga (Acacia aneura F. Muell. ex Benth.) dominated vegetation in semiarid Queensland, Australia." Rangeland Journal 38, no. 4 (2016): 391. http://dx.doi.org/10.1071/rj15109.
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Changes to fire regimes associated with European colonisation are implicated in declines in biodiversity and productivity in rangelands globally. However, for many areas there is incomplete knowledge of historical fire regimes and purported changes can become accepted wisdom with little empirical evidence. In the Mulga Lands of south-western Queensland, the dominant narrative implicates reduced fire frequency as a cause of woody vegetation thickening. We present a fire history of the Mulga Lands since pastoral exploration in the 1840s based on a review of explorer and early pastoralist journals, newspaper articles, interviews with long-term landholders and collation of satellite imagery. Fires in mulga communities are infrequent and only occur after at least two years of above-average summer rainfall. The assumption of regular pre-pastoral fires is not supported by available evidence. Since pastoral settlement in the 1860s, fire events affecting >1000 km2 have occurred seven times (1891–1892, 1904, 1918, 1950–1951, 1956–1957, 1976–1979 and 2011–2013), with only the 1950s fires affecting a >10% of the total area of mulga-dominated vegetation. We argue that fire is limited by fuel loads, which are in turn limited by rainfall events occurring only a few times a century. Even in the absence of grazing and active fire suppression fire intervals would be extremely long, perhaps 30–50 years in relatively fire-prone communities and much longer throughout most of the region. Combined with quantitative studies of fire and tree and shrub population dynamics, detailed fire histories will allow for more informed and nuanced debates about the role of fire in rangelands subject to abrupt management upheavals.
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McDaniel, Thomas W., Carissa L. Wonkka, Morgan L. Treadwell, and Urs P. Kreuter. "Factors Influencing County Commissioners’ Decisions about Burn Bans in the Southern Plains, USA." Land 10, no. 7 (June 30, 2021): 686. http://dx.doi.org/10.3390/land10070686.
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Woody plant encroachment in North American rangelands has led to calls for greater use of prescribed fire to reduce fuel loads and restore grazing productivity and grassland biodiversity. However, the use of prescribed fire during periods when woody plant mortality is maximized has often been limited by temporary restrictions on outdoor burning enacted by regional or local governmental entities. This study reports the results of a survey assessing the familiarity with and attitudes toward prescribed fire in Texas and Oklahoma, USA, of officials tasked with implementing restrictions on outdoor burning and how these attitudes influence their decisions. Most responding officials considered prescribed fire to be a safe and beneficial land management tool that should be used more frequently. Self-reported familiarity with prescribed fire was the most significant explanatory variable for this attitude. Further, familiarity with prescribed fire was influenced by respondent participation in or being invited to participate in a prescribed fire. Such invitations came mostly from private landowners. Landowners wishing to use prescribed fire may benefit from building trust with local officials by demonstrating they are qualified to conduct such fires safely. This could help reduce the frequency of burn restrictions and may increase the likelihood that officials will grant burn ban exemptions to qualified burn managers. Additionally, because officials’ primary sources of prescribed fire information were reported to be local fire departments and emergency services, educating those entities about the benefits of prescribed fire for reducing wildfire risks could help reduce pressure on officials to enact or maintain burning restrictions. These findings highlight opportunities for reducing the frequency of burning restrictions, increasing opportunities for land managers to effectively halt or reverse woody plant encroachment.
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Frost, Scott M., Martin E. Alexander, and Michael J. Jenkins. "The Application of Fire Behavior Modeling to Fuel Treatment Assessments at Army Garrison Camp Williams, Utah." Fire 5, no. 3 (June 9, 2022): 78. http://dx.doi.org/10.3390/fire5030078.
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Large wildfires (>40 ha in size) occur about every three years within Army Garrison Camp Williams, located near South Jordan, Utah, USA. In 2010 and 2012, wildfires originating on the practice firing range burned beyond the camp’s boundaries into the adjacent wildland-urban interface areas. The political and public reaction to these escaped fires was intense. Fire researchers at Utah State University were asked if a spatially organized system of fuel treatments could be developed to prevent such incidents in the future. We used a combination of empirically based guidelines and semi-physical fire modeling systems, coupled with climatological data, to make assessments of fire behavior potential for the sagebrush steppe vegetation/fuel types found in AGCW, that also considered slope steepness. The results suggested the need for removal of woody vegetation within 20 m of firebreaks and a minimum firebreak width of 8.0 m in grassland fuels. In stands of juniper, a canopy coverage of 25% or less is recommended. In Gambel oak stands along the northern boundary of the installation, a fuelbreak width of 60 m for secondary breaks (used for segmenting large areas of fuels) and 90 m for primary breaks (used for protecting urban development and valuable natural resources) is recommended.