Fuel and fire characteristics in savanna - woodland of West Africa in relation to grazing and dominant grass type

2007 ◽  
Vol 16 (5) ◽  
pp. 531 ◽  
Author(s):  
Patrice Savadogo ◽  
Didier Zida ◽  
Louis Sawadogo ◽  
Daniel Tiveau ◽  
Mulualem Tigabu ◽  
...  
Keyword(s):  
Prescribed Burning ◽  
Management Tool ◽  
Fuel Load ◽  
Maximum Temperature ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Savanna Woodland ◽  
Vegetation Height ◽  
Average Maximum ◽  
Dominant Grass

Fuel characteristics, fire behaviour and temperature were studied in relation to grazing, dominant grass type and wind direction in West African savanna–woodland by lighting 32 prescribed early fires. Grazing significantly reduced the vegetation height, total fuel load, and dead and live fuel fractions whereas plots dominated by perennial grasses had higher values for vegetation height, total fuel load and the quantity of live fuel load. Although fire intensity remained insensitive (P > 0.05) to any of these factors, fuel consumption was significantly (P = 0.021) reduced by grazing, rate of spread was faster in head fire (P = 0.012), and flame length was shorter in head fire than back fire (P = 0.044). The average maximum temperature was higher (P < 0.05) on non-grazed plots, on plots dominated by annual grasses, on plots subjected to head fire, and at the soil surface. Lethal temperature residence time showed a nearly similar trend to fire temperature. Wind speed and total fuel load were best predictors of fire behaviour parameters (R2 ranging from 0.557 to 0.862). It can be concluded that grazing could be used as a management tool to modify fire behaviour, back fire should be carried out during prescribed burning to lower fire severity, and the fire behaviour models can be employed to guide prescribed early fire in the study area.

Short-term effect of fuel treatments on fire behaviour in a mixed heathland: a comparative assessment in an outdoor wind tunnel

2014 ◽  
Vol 23 (8) ◽  
pp. 1097 ◽  
Author(s):  
Eva Marino ◽  
Carmen Hernando ◽  
Javier Madrigal ◽  
Mercedes Guijarro
Keyword(s):  
Wind Tunnel ◽  
Prescribed Burning ◽  
Flame Height ◽  
Fuel Load ◽  
Fire Intensity ◽  
Fuel Management ◽  
Fire Behaviour ◽  
Fuel Treatments ◽  
Relevant Effect ◽  
Significant Difference

Fuel management is one of the main challenges for wildfire prevention in the Mediterranean region, where wildfires have important environmental and socioeconomic effects. Different treatments are usually applied in fire-prone shrubland to try to modify its flammability. However, a knowledge gap on the effectiveness of fuel management techniques still exists. We studied the effects of two mechanical treatments (shrub crushing and shrub clearing with removal) and of prescribed burning, on fire behaviour, and compared them with untreated vegetation. Experimental burns in 0.8 × 6 m samples of regenerated shrubs 2 years after treatments were performed in an outdoor wind tunnel. All fuel treatments effectively modified fire behaviour, but no significant difference between treatment types was observed. Shrub fuel structure was the main factor affecting fire behaviour. Reduction of fuel load and height, especially necromass fraction, decreased flame height and fire intensity but did not affect fire rate of spread. Moisture contents of live and dead fuel fractions were not significant as independent parameters, but the average moisture level of the shrub fuel complex showed a relevant effect in determining fire behaviour. Temperature regime within and above the shrubs was also related to shrub fuel structure. This study contributes to understanding fuel management in shrubland by providing information about different fuel treatments effects on fire behaviour.

scholarly journals Prescribed burning in a mediterranean-climate region mitigates the disturbance by bushfire to a critical food resource for an endangered bird, the Carnaby’s cockatoo

Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Valerie S. Densmore ◽  
Emma S. Clingan
Keyword(s):  
Seed Production ◽  
Prescribed Burning ◽  
Fire Regime ◽  
Fire Hazard ◽  
Food Resource ◽  
Management Tool ◽  
Fire Intensity ◽  
Prescribed Burns ◽  
Low Intensity ◽  
Percentage Survival

Abstract Background Prescribed burning is used to reduce fire hazard in highly flammable vegetation types, including Banksia L.f. woodland that occurs on the Swan Coastal Plain (SCP), Western Australia, Australia. The 2016 census recorded well over 1.9 million people living on the SCP, which also encompasses Perth, the fourth largest city in Australia. Banksia woodland is prone to frequent ignitions that can cause extensive bushfires that consume canopy-stored banksia seeds, a critical food resource for an endangered bird, the Carnaby’s cockatoo (Calyptorynchus latirostris, Carnaby 1948). The time needed for banksias to reach maturity and maximum seed production is several years longer than the typical interval between prescribed burns. We compared prescribed burns to bushfires and unburned sites at three locations in banksia woodland to determine whether low-intensity prescribed burns affect the number of adult banksias and their seed production. Study sites were matched to the same vegetation complex, fire regime, and time-since-fire to isolate fire intensity as a variable. Results Headfire rates of spread and differenced normalized burn ratios indicated that prescribed burning was generally of a much lower intensity than bushfire. The percentage survival of adult banksias and their production of cones and follicles (seeds) did not decrease during the first three years following a prescribed burn. However, survival and seed production were significantly diminished followed high-intensity bushfire. Thus, carrying capacity for Carnaby’s cockatoo was unchanged by prescribed burning but decreased markedly following bushfire in banksia woodland. Conclusions These results suggest that prescribed burning is markedly different from bushfire when considering appropriate fire intervals to conserve canopy habitats in fire-resilient vegetation communities. Therefore, low-intensity prescribed burning represents a viable management tool to reduce the frequency and extent of bushfire impacts on banksia woodland and Carnaby’s cockatoo.

Influence of prescribed burning on fruit production in Proteaceae

2010 ◽  
Vol 16 (1) ◽  
pp. 46 ◽  
Author(s):  
T. D. Penman ◽  
S. H. Penman
Keyword(s):  
Community Structure ◽  
Reproductive Output ◽  
Prescribed Burning ◽  
Fire Regimes ◽  
Fruit Production ◽  
Management Tool ◽  
Fire Intensity ◽  
Term Study ◽  
Long Term Study

Prescribed burning is applied worldwide as a forest management tool. It is broadly accepted that altered fire regimes can directly impact upon community structure and composition, but little is known about the indirect effects of altered fire regimes on the mechanisms that produce community-level changes such as changes to the reproductive output of individual plants, hence populations. We examined the reproductive output of four species of Proteaceae within a long term study site where disturbance histories for the last twenty years have been accurately recorded on 216 plots. Frequent fire was found to increase woody fruit production in Banksia marginata, but had no apparent effect on B. serrata, Hakea eriantha or H. sericea. Results of this study vary from a similar study which examined the effect of wildfires. The differences observed are likely to reflect the differing impacts of fire intensity on these species. Indirect changes in fruit production may result in changes in reproductive success of species which in turn may affect vegetation community structure and faunal habitat.

scholarly journals Estimating Fuel Consumption for the Upper Coastal Plain of South Carolina

2010 ◽  
Vol 34 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Scott L. Goodrick ◽  
Dan Shea ◽  
John Blake
Keyword(s):  
South Carolina ◽  
Air Quality ◽  
Fuel Consumption ◽  
Prescribed Fire ◽  
Coastal Plain ◽  
Prescribed Burning ◽  
Management Tool ◽  
Fuel Load ◽  
Trade Offs ◽  
Continued Use

Abstract Recent changes in air quality regulations present a potential obstacle to continued use of prescribed fire as a land management tool. Lowering of the acceptable daily concentration of particulate matter from 65 to 35 μg/m3 will bring much closer scrutiny of prescribed burning practices from the air quality community. To work within this narrow window, land managers need simple tools to allow them to estimate their potential emissions and examine trade-offs between continued use of prescribed fire and other means of fuels management. A critical part of the emissions estimation process is determining the amount of fuel consumed during the burn. This study combines results from a number of studies along the Upper Coastal Plain of South Carolina to arrive at a simple means of estimating total fuel consumption on prescribed fires. The result is a simple linear relationship that determines the total fuel consumed as a function of the product of the preburn fuel load and the burning index of the National Fire Danger Rating System.

scholarly journals Prescribed Burning as A Management Tool to Destroy Dry Seeds of Invasive Conifers in Heathland in Denmark

Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 432
Author(s):  
Christian Andreasen ◽  
Kasper Rossing ◽  
Christian Ritz
Keyword(s):  
High Temperature ◽  
Prescribed Burning ◽  
Germination Rate ◽  
Management Tool ◽  
Fuel Load ◽  
The Mean ◽  
Temperature Records ◽  
Conifer Trees ◽  
The Relationship ◽  
Practical Constraints

Non-indigenous conifers are considered invasive to the coastal dune heathland in Denmark, and massive clearing is carried out in an attempt to recreate and keep the original heathland. Burning is a common method for managing, but its feasibility to control the seed bank of conifers has not been investigated. This project shows that the burning of logged conifer trees will often eliminate seeds of lodgepole pine, mugo pine and Sitka spruce, even when the seeds were placed into a depth of five centimeters in the soil. The effect on seeds depends on the fuel load and the fire conditions (e.g., dryness, wind, and temperature). If the seeds were exposed to a high temperature, the seeds were not able to germinate afterward. The temperature was about 80 °C for all species. If the sum of temperatures based on temperature records every 30 s exceeded between 12,000 and 14,000 °C no seeds were able to germinate. The relationship between the mean temperature of the burns and the germination rate at seeds placed in various soil depths was modelled. Findings should be interpreted cautiously as each depth-species combinations were not replicated in space or time due to practical constraints.

Simulating the effectiveness of prescribed burning at altering wildfire behaviour in Tasmania, Australia

2018 ◽  
Vol 27 (1) ◽  
pp. 15 ◽  
Author(s):  
James M. Furlaud ◽  
Grant J. Williamson ◽  
David M. J. S. Bowman
Keyword(s):  
Prescribed Burning ◽  
Vegetation Type ◽  
Weather Conditions ◽  
Statistical Modelling ◽  
Fire Intensity ◽  
Fire Weather ◽  
Fire Behaviour ◽  
Large Area ◽  
Treatment Scenario ◽  
Wildfire Hazard

Prescribed burning is a widely accepted wildfire hazard reduction technique; however, knowledge of its effectiveness remains limited. To address this, we employ simulations of a widely used fire behaviour model across the ecologically diverse Australian island state of Tasmania. We simulate three broad scenarios: (1) no fuel treatment, (2) a maximal treatment, with the most possible prescribed burning within ecological constraints, and (3) 12 hypothetically more implementable state-wide prescribed-burning plans. In all simulations, we standardised fire-weather inputs to represent regionally typical dangerous fire-weather conditions. Statistical modelling showed that an unrealistically large maximal treatment scenario could reduce fire intensity in three flammable vegetation types, and reduce fire probability in almost every vegetation type. However, leverage analysis of the 12 more-realistic implementable plans indicated that such prescribed burning would have only a minimal effect, if any, on fire extent and that none of these prescribed-burning plans substantially reduced fire intensity. The study highlights that prescribed burning can theoretically mitigate wildfire, but that an unrealistically large area would need to be treated to affect fire behaviour across the island. Rather, optimisation of prescribed burning requires careful landscape design at the local scale. Such designs should be based on improved fire behaviour modelling, empirical measurement of fuels and analysis of actual wildfires.

Effects of fuel load and moisture content on fire behaviour and heating in masticated litter-dominated fuels

2013 ◽  
Vol 22 (4) ◽  
pp. 440 ◽  
Author(s):  
Jesse K. Kreye ◽  
Leda N. Kobziar ◽  
Wayne C. Zipperer
Keyword(s):  
Moisture Content ◽  
Fuel Load ◽  
Maximum Temperature ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Pine Flatwoods ◽  
Rate Of Spread ◽  
Soil Temperatures ◽  
Fuel Moisture Content ◽  
In Fire

Mechanical fuels treatments are being used in fire-prone ecosystems where fuel loading poses a hazard, yet little research elucidating subsequent fire behaviour exists, especially in litter-dominated fuelbeds. To address this deficiency, we burned constructed fuelbeds from masticated sites in pine flatwoods forests in northern Florida with palmetto-dominated understoreys and examined the effects of fuel load and fuel moisture content (FMC) on fire behaviour. Flame lengths (49–140 cm) and fireline intensity (183–773 kJ m–1 s–1) increased with loading (10–30 Mg ha–1) and were reduced by 40 and 47% with increasing FMC from 9 to 13%. Rate of spread was not influenced by fuel load, but doubled under drier FMC. Fuel consumption was >90% for all burns. Soil temperatures were influenced by both fuel load and FMC, but never reached lethal temperatures (60°C). However, temperatures of thermocouple probes placed at the fuelbed surface reached 274–503°C. Probe maximum temperature and duration at temperatures ≥60°C (9.5–20.0°C min) both increased with fuel load, but were unaffected by FMC. The fire behaviour observed in these unique litter-dominated fuelbeds provides additional insight into the burning characteristics of masticated fuels in general.

scholarly journals The impact of aging on laboratory fire behaviour in masticated shrub fuelbeds of California and Oregon, USA

2016 ◽  
Vol 25 (9) ◽  
pp. 1002 ◽  
Author(s):  
Jesse K. Kreye ◽  
J. Morgan Varner ◽  
Jeffrey M. Kane ◽  
Eric E. Knapp ◽  
Warren P. Reed
Keyword(s):  
Tree Mortality ◽  
Management Practice ◽  
Fire Hazard ◽  
Woody Debris ◽  
Fuel Load ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Slow Combustion ◽  
The Impact ◽  
Over Time

Mastication of shrubs and small trees to reduce fire hazard has become a widespread management practice, yet many aspects of the fire behaviour of these unique woody fuelbeds remain poorly understood. To examine the effects of fuelbed aging on fire behaviour, we conducted laboratory burns with masticated Arctostaphylos spp. and Ceanothus spp. woody debris that ranged from 2 to 16 years since treatment. Masticated fuels that were 10 years or older burned with 18 to 29% shorter flame heights and 19% lower fireline intensities compared with the younger fuelbeds across three different fuel loads (25, 50 and 75 Mg ha–1). Older fuelbeds smouldered for almost 50% longer than the younger masticated fuelbeds. Fuel consumption was 96% in the two higher fuel load categories regardless of fuelbed age, whereas consumption was 77% in the lighter fuel load. Fire intensity in masticated fuels may decrease over time owing to particle degradation, but in dry environments where decomposition is slow, combustion of the remaining fuels may still pose risks for tree mortality and smoke production associated with protracted smouldering.

scholarly journals Volatile and semi-volatile organic compounds in smoke exposure of firefighters during prescribed burning in the Mediterranean region

2010 ◽  
Vol 19 (5) ◽  
pp. 606 ◽  
Author(s):  
Toussaint Barboni ◽  
Magali Cannac ◽  
Vanina Pasqualini ◽  
Albert Simeoni ◽  
Eric Leoni ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Prescribed Burning ◽  
Management Tool ◽  
Fire Intensity ◽  
Short Term ◽  
Limit Value ◽  
Exposure Limit ◽  
Short Term Exposure ◽  
Volatile Organic

Prescribed fires can be used as a forest management tool to reduce the severity of wildfires. Thus, over prolonged and repeated periods, firefighters are exposed to toxic air contaminants. This work consisted in collecting and analysing smoke released by typical Mediterranean vegetation during prescribed burning. Sampling was performed at five active zones on the island of Corsica. Seventy‐nine compounds were identified: volatile organic compounds and semi‐volatile organic compounds, including polycyclic aromatic hydrocarbons. Depending on exposure levels, the toxins present in smoke may cause short‐term or long‐term damage to firefighters’ health. The dangerous compounds emitted, benzene, toluene, ethylbenzene and xylenes, were quantified. Their concentrations varied as a function of the study site. These variations were due to the intrinsic and extrinsic characteristics of the fire site (e.g. plant species, fire intensity and wind). Our results show that benzene concentration is high during prescribed burning, close to the exposure limit value or short‐term exposure limit. Benzene can be considered as a toxicity tracer for prescribed burning because its concentration was above the exposure limit value at all the study sites. The authors suggest that respirators should be used to protect staff during prescribed burning operations.

Soil temperatures during and following low-intensity prescribed burning in a Eucalyptus pauciflora forest

Soil Research ◽  
1986 ◽  
Vol 24 (1) ◽  
pp. 33 ◽  
Author(s):  
RJ Raison ◽  
PV Woods ◽  
BF Jakobsen ◽  
GAV Bary
Keyword(s):  
Organic Matter ◽  
Prescribed Burning ◽  
Organic Matter Content ◽  
Heat Content ◽  
Soil Surface ◽  
Maximum Temperature ◽  
Fire Intensity ◽  
Daily Maximum ◽  
Low Intensity ◽  
Maximum Temperatures

Temperatures at the soil surface and at several soil depths were measured during, and at intervals, for 33 months after a low-intensity prescribed burn in a subalpine Eucalyptus pauciflora forest. The high organic matter content, low bulk density, and low moisture content of the surface soil caused steep soil temperature gradients to be generated during the fire. Mean maximum temperatures during the fire were 600 � 50, 450 � 52, 54 � 5 and 42 � 5�C in the litter and at 0, 2 and 5 cm soil depths respectively. The highest temperatures recorded at 0, 2 and 5 cm depths were 703, 94 and 44�C. Temperatures exceeding 200�C, which result in volatilization of N from soil organic matter, were estimated to have occurred in the upper 3 mm of the soil. Byram fire intensity tended to be negatively correlated with the maximum temperature measured at the soil surface, but was not correlated with the amount of heat absorbed by black cans (thermal integrators) or the increase in the heat content of the soil. After the burn, the mean daily maximum temperatures in the soil were markedly higher on burnt than on unburnt sites. For example, soon after burning increases were 6, 10, 4 and 4�C at 0, 2, 5 and 10 cm depths, respectively, during a 5-day summer period. Mean daily minimum temperatures on recently burnt plots were similar to or slightly lower than those on unburnt areas. Average day-time temperature in recently burnt forest in summer was elevated by up to 8 and 4�C at 0 and 10 cm soil depths.

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