scholarly journals Utah juniper and two-needle piñon reduction alters fuel loads

2015 ◽  
Vol 24 (2) ◽  
pp. 236 ◽  
Author(s):  
Kert R. Young ◽  
Bruce A. Roundy ◽  
Stephen C. Bunting ◽  
Dennis L. Eggett
Keyword(s):  
Block Design ◽  
Tree Cover ◽  
Fuel Load ◽  
Fire Intensity ◽  
Crown Fire ◽  
Understorey Vegetation ◽  
Fuel Loads ◽  
Canopy Fuels ◽  
Utah Juniper ◽  
Pinus Spp

Juniper (Juniperus spp.) and piñon (Pinus spp.) trees have encroached millions of hectares of sagebrush (Artemisia spp.)–bunchgrass communities. Juniper–piñon trees are treated to reduce canopy fuel loads and crown fire potential. We measured the effects of juniper–piñon infilling and fuel-reduction treatments on fuel load characteristics at four locations in Utah. At each location, treatment areas were burned, left untreated, or trees were cut or masticated in a randomised complete-block design. We measured standing and downed fuels by size and type along 30-m transects on 15 subplots (30 × 33 m) per location before and 1–3 years after treatment. Increased tree cover was associated with decreased shrub and herbaceous fuel loads (P < 0.01). By 2 years post-treatment, herbaceous fuel loads were greater than pretreatment in all treated areas (P < 0.01). Cut and mastication treatments increased surface woody 10- and 100-h fuel loads and wood/bark cover (P < 0.01). Masticated-tree depth was a good estimator of fuel loads (R2 = 92). The conversion of canopy fuels to surface fuels reduced fuels that enable crown fire and extreme fire intensity. Cool-season prescribed fire may need to follow mechanical treatments to reduce surface fuel and the potential for wildfire damage to perennial understorey vegetation.

scholarly journals Estimación de la distribución vertical de combustibles finos del dosel de copas en masas de Pinus sylvestris empleando datos LiDAR de baja densidad

2019 ◽  
pp. 1 ◽  
Author(s):  
L. A. Fidalgo-González ◽  
S. Arellano-Pérez ◽  
J. G. Álvarez-González ◽  
F. Castedo-Dorado ◽  
A. D. Ruiz-González ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Fire Hazard ◽  
National Forest Inventory ◽  
Fuel Load ◽  
Crown Fire ◽  
Cross Model ◽  
Canopy Fuels ◽  
Structural Variables ◽  
Fire Initiation ◽  
Using Data

<p>Canopy fuel load, canopy bulk density and canopy base height are structural variables used to predict crown fire initiation and spread. Direct measurement of these variables is not functional, and they are usually estimated indirectly by modelling. Advances in fire behaviour modelling require accurate and landscape scale estimates of the complete vertical distribution of canopy fuels. The goal of the present study is to model the vertical profile of available canopy fuels in Scots pine stands by using data from the Spanish national forest inventory and low-density LiDAR data (0.5 first returns  m<sup>–2</sup>) provided by Spanish PNOA project (Plan Nacional de Ortofotografía Aérea). In a first step, the vertical distribution of the canopy fuel load was modelled using the Weibull probability density function. In a second step, a system of models was fitted to relate the canopy variables to Lidar-derived metrics. Models were fitted simultaneously to compensate the effects of the inherent cross-model correlation between errors. Heteroscedasticity was also analyzed, but correction in the fitting process was not necessary. The estimated canopy fuel load profiles from LiDAR-derived metrics explained 41% of the variation in canopy fuel load in the analysed plots. The proposed models can be used to assess the effectiveness of different forest management alternatives for reducing crown fire hazard.</p>

Effects of fire intensity on soil chemistry in a eucalypt forest

Soil Research ◽  
1991 ◽  
Vol 29 (1) ◽  
pp. 25 ◽  
Author(s):  
IB Tomkins ◽  
JD Kellas ◽  
KG Tolhurst ◽  
DA Oswin
Keyword(s):  
Soil Depth ◽  
Exchange Capacity ◽  
Fuel Load ◽  
Fire Intensity ◽  
Chemical Parameters ◽  
Podzolic Soils ◽  
Fuel Loads ◽  
Eucalypt Forest ◽  
Before And After ◽  
Total P

Soil samples taken in the Wombat State Forest in Victoria, at depths of 0-2, 2-5, and 5-10 cm before and after burning fuel loads of 0 (unburnt control), 15, 50, 150, and 300 t ha-1 were analysed for pH, exchangeable cations and cation exchange capacity, available and total P, organic carbon and soil moisture, over a 2-year, 2000 mm rainfall period. Short term responses (up to 6 months) occurred in levels of exchangeable NH4+, K+, and Mg2+, and long term changes (2 years or longer) over the period of the study were observed for pH, available and total P and exchangeable ca2+ at the 0-2 cm soil depth for the burnt treatments. Following burning (and 108 mm of rain), changes in soil chemical parameters were strongly correlated with fuel load and the quantity of fuel burnt. Changes through the 0-10 cm profile for the various chemical parameters are described, together with seasonal variations. For similar yellow podzolic soils, measurement of soil pH may be a useful criterion for monitoring soil chemical changes following slash and fuel reduction burning, provided that accurate estimates of fuel loads, composition and amount burnt can be established.

Estimating canopy fuel characteristics in five conifer stands in the western United States using tree and stand measurements

2006 ◽  
Vol 36 (11) ◽  
pp. 2803-2814 ◽  
Author(s):  
Elizabeth Reinhardt ◽  
Joe Scott ◽  
Kathy Gray ◽  
Robert Keane
Keyword(s):  
Tree Height ◽  
Fuel Load ◽  
Computational Techniques ◽  
Crown Fire ◽  
Canopy Fuels ◽  
Adjustment Factors ◽  
Fuel Characteristics ◽  
Crown Base Height ◽  
Interior West ◽  
The Vertical Distribution

Assessment of crown fire potential requires quantification of canopy fuels. In this study, canopy fuels were measured destructively on plots in five Interior West conifer stands. Observed canopy bulk density, canopy fuel load, and vertical profiles of canopy fuels are compared with those estimated from stand data using several computational techniques. An allometric approach to estimating these canopy fuel characteristics was useful, but, for accuracy, estimates of vertical biomass distribution and site-adjustment factors were required. Available crown fuel was estimated separately for each tree according to species, diameter, and crown class. The vertical distribution of this fuel was then modeled within each tree crown on the basis of tree height and crown base height. Summing across trees within the stand at every height yielded an estimated vertical profile of canopy fuel that approximated the observed distribution.

Landscape-scale changes in canopy fuels and potential fire behaviour following ponderosa pine restoration treatments

2008 ◽  
Vol 17 (2) ◽  
pp. 293 ◽  
Author(s):  
John P. Roccaforte ◽  
Peter Z. Fulé ◽  
W. Wallace Covington
Keyword(s):  
Ponderosa Pine ◽  
Landscape Scale ◽  
Fuel Load ◽  
Permanent Plots ◽  
Crown Fire ◽  
Fire Behaviour ◽  
Treated Area ◽  
Canopy Fuels ◽  
Behaviour Changes ◽  
Historical Forest

We evaluated canopy fuels and potential fire behaviour changes following landscape-scale restoration treatments in a ponderosa pine forest at Mt Trumbull, Arizona, USA. The goal of the project was to restore historical forest structure by thinning and burning, thereby reducing canopy fuels and minimising active crown fire potential. We measured 117 permanent plots before (1996–97) and after (2003) treatments. The plots were evenly distributed across the landscape and represented an area of ~1200 ha, about half of which was an untreated control. We compared canopy fuel estimates using three different methods to assess whether fire behaviour modelling outputs were sensitive to the choice of canopy fuel equation. Treatments decreased canopy fuel load by 43–50% from 0.77–1.83 kg m–2 to 0.44–0.91 kg m–2 (the range of values reflects the different canopy fuel equations) and decreased canopy bulk density by 42–61% from 0.038–0.172 kg m–3 to 0.022–0.067 kg m–3 in the treated area, while slight increases occurred in the control. We applied two fire models to estimate potential fire behaviour: FlamMap and NEXUS. These models differ in several important features but predicted outcomes were consistent: under extreme drought and wind conditions, the proportion of the landscape susceptible to active crown fire decreased in the treated area while little change occurred in the control.

Predicting the Height to Live Crown Base in Plantations of Four Boreal Forest Species

1994 ◽  
Vol 4 (2) ◽  
pp. 103 ◽  
Author(s):  
RS Mc Alpine ◽  
MW Hobbs
Keyword(s):  
Boreal Forest ◽  
Red Pine ◽  
Fuel Load ◽  
Fire Intensity ◽  
Crown Fire ◽  
Forest Species ◽  
Plantation Forest ◽  
Surface Fire ◽  
Forest Fuels ◽  
Stand Height

A critical parameter for the initiation and propagation of a crown fire in the boreal forest is the height to the base of the live crown. The initiation of a crown fire requires that the surface fire intensity must be sufficient to ''jump'' the gap between the forest floor and the live crown and ignite crown fuels. The greater the height of the live crown base, the more intense the surface fire must be to induce a crown fire. Plantation forest fuels tend to be more structured and have less variability than naturally regenerated areas, allowing prediction of the height of the live crown base to be made from commonly available stand parameters. Plantations of four commonly planted boreal forest species were sampled over a variety of age classes to determine a predictive relationship for height to live crown base. Height to live crown base can be predicted from stand height and density for Pinus banksiana (jack pine), Pinus resinosa (red pine), Picea mariana (black spruce), and Picea glauca (white spruce). In addition to predicting the height to live crown base, parameters within the equations lead to other observations. Crown foliar fuel loading does not change with stand height following crown closure in red pine but in the other three species crown fuel load increases as the stand grows taller.

scholarly journals Recent Crown Thinning in a Boreal Black Spruce Forest Does Not Reduce Spread Rate nor Total Fuel Consumption: Results from an Experimental Crown Fire in Alberta, Canada

Fire ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 28 ◽  
Author(s):  
Dan K. Thompson ◽  
Dave Schroeder ◽  
Sophie L. Wilkinson ◽  
Quinn Barber ◽  
Greg Baxter ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Black Spruce ◽  
High Surface ◽  
Organic Soil ◽  
Fuel Load ◽  
Fire Intensity ◽  
Stem Density ◽  
Crown Fire ◽  
Spread Rate ◽  
Limited Effectiveness

A 3.6 ha experimental fire was conducted in a black spruce peatland forest that had undergone thinning the year prior. After 50 m of spread in a natural stand at 35–60 m min−1, the crown fire (43,000 kW m−1 intensity using Byram’s method) encountered the 50% stem removal treatment; spread rates in the treatment were 50–60 m min−1. Fuel consumption in the control (2.75 kg m−2) was comparable to the treatment (2.35 kg m−2). Proxy measurements of fire intensity using in-stand heat flux sensors as well as photogrammetric flame heights had detected intensity reductions to 30–40% of the control. Crown fuel load reductions (compensated by higher surface fuel load) appear to be the most significant contributor to the decline in intensity, despite drier surface fuels in the treatment. The burn depth of 5 cm in moss and organic soil did not differ between control and treatment. These observations point to the limited effectiveness (likely reductions in crown fire intensity but not spread rate) of stem removal in boreal black spruce fuel types with high stem density, low crown base height and high surface fuel load. The observed fire behaviour impacts differ from drier conifer forests across North America.

scholarly journals The spatial dimensions of Savanna fire ecology in Kruger National Park, South Africa

2015 ◽  
Author(s):  
◽  
Daniel Godwin
Keyword(s):  
South Africa ◽  
National Park ◽  
Fire Severity ◽  
Kruger National Park ◽  
Tree Cover ◽  
Annual Precipitation ◽  
Fuel Load ◽  
Fire Intensity ◽  
Mean Annual Precipitation ◽  
Woody Cover

Savannas are thought to be bistable with forests potentially occurring above [about]650 mm / yr of Mean Annual Precipitation (MAP) due to the limiting effects of fire on tree cover. This is predicated on two assumptions: 1) fires increasingly limit woody cover in more mesic (> 650 MAP) savannas and 2) increasing tree cover produces feedbacks that reduce fire intensity. These assumptions are investigated in a spatially explicit framework. We use Kruger National Park (KNP), South Africa as our study system, in part due to the wide range of frequency of fires, the large variation in natural communities and rainfall, and the large body of previous research for comparisons and modeling efforts. To investigate whether tree cover produces feedbacks on fire intensity, we measured fire behavior as a function of grass fuel load and woody cover in experimental burns within KNP. We found weak but positive relationships (not negative, as assumed) between woody cover and fire intensity, independent of grass fuel load, and no relationship between tree cover and grass fuel load. At a landscape scale, we modeled the factors predicted to drive fire severity in KNP. We observed that fireline intensity is a strong predictor of many estimations of fire severity in small fires, but across larger fires, rainfall and woody cover likewise can predict impacts on herbaceous consumption and woody cover, respectively. Lastly, to investigate whether trees escape fire less often in more mesic savannas, we used a stochastic model parameterized with real data. After a review of published growth rates, we modeled fire escape probability using mean annual precipitation, fire frequency, and fireline intensity values across KNP. When accounting for species turnover across rainfall gradients, we found a nearly flat relationship between the probability of individuals escaping fire and rainfall. Our research challenges two key assumptions for fire-mediated bistability of mesic savannas.

scholarly journals Impacts of increasing fine fuel loads on acorn germination and early growth of oak seedlings

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Rachel E. Nation ◽  
Heather D. Alexander ◽  
Geoff Denny ◽  
Jennifer K. McDaniel ◽  
Alison K. Paulson
Keyword(s):  
Prescribed Fire ◽  
Germination Rate ◽  
Growth Patterns ◽  
Leaf Number ◽  
Fuel Load ◽  
Quercus Alba ◽  
White Oak ◽  
Fuel Treatment ◽  
Basal Diameter ◽  
Fuel Loads

Abstract Background Prescribed fire is increasingly used to restore and maintain upland oak (Quercus L. spp.) ecosystems in the central and eastern US. However, little is known about how prescribed fire affects recently fallen acorns under different fine fuel loads, which can vary with stand composition and basal area, burn season, and fire frequency. We conducted plot-level (1 m2) burns in an upland oak stand in northern Mississippi, USA, during December 2018, using single (i.e., ambient), double, and triple fine fuel loads, representative of those in nearby unburned and recently fire-treated, closed-canopy stands. Pre burn, we placed 30 acorns each of white oak (Quercus alba L.) and Shumard oak (Quercus shumardii Buckley) ~1 cm below the litter surface in five plots of each fuel treatment. Immediately post burn, we planted unburned and burned acorns in a greenhouse. After ~50% of each species’ unburned acorns germinated, we measured percent germination and height, basal diameter, and leaf number of germinating seedlings weekly for 11 weeks. Then, we harvested seedlings to determine above- and belowground biomass. Results The single fuel treatment reduced acorn germination rates of both species to ~40% compared to ~88% in unburned acorns. When burned in double and triple fuel loads, acorns of both species had a <5% germination rate. There was no difference in basal diameter, leaf number, or biomass of seedlings from burned versus unburned acorns for either species. However, seedlings originating from burned acorns of both species were ~11% shorter than those from unburned acorns. Thus, both species responded similarly to fuel load treatments. Conclusions Acorns of both species exhibited greater survival with lower fine fuel loads, and consequently lower percent fuel consumption. Acorns germinating post fire generally produced seedlings with growth patterns similar to seedlings originating from unburned acorns. These findings indicate that regular, repeated prescribed fires or canopy reductions that limit fine fuel accumulation and create heterogeneous fuel beds are likely to increase acorn germination rates relative to unburned sites or those with recently introduced fire.

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.

scholarly journals Modelling and mitigating dose to firefighters from inhalation of radionuclides in wildland fire smoke

2015 ◽  
Vol 24 (5) ◽  
pp. 723 ◽  
Author(s):  
Brian J. Viner ◽  
Tim Jannik ◽  
Daniel Stone ◽  
Allan Hepworth ◽  
Luke Naeher ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Wildland Fire ◽  
Radioactive Material ◽  
Fuel Load ◽  
Base Case ◽  
Published Data ◽  
Case Scenario ◽  
Base Case Scenario ◽  
Fuel Loads ◽  
Radiological Dose

Firefighters responding to wildland fires where surface litter and vegetation contain radiological contamination will receive a radiological dose by inhaling resuspended radioactive material in the smoke. This may increase their lifetime risk of contracting certain types of cancer. Using published data, we modelled hypothetical radionuclide emissions, dispersion and dose for 70th and 97th percentile environmental conditions and for average and high fuel loads at the Savannah River Site. We predicted downwind concentration and potential dose to firefighters for radionuclides of interest (137Cs, 238Pu, 90Sr and 210Po). Predicted concentrations exceeded dose guidelines in the base case scenario emissions of 1.0 × 107 Bq ha–1 for 238Pu at 70th percentile environmental conditions and average fuel load levels for both 4- and 14-h shifts. Under 97th percentile environmental conditions and high fuel loads, dose guidelines were exceeded for several reported cases for 90Sr, 238Pu and 210Po. The potential for exceeding dose guidelines was mitigated by including plume rise (>2 m s–1) or moving a small distance from the fire owing to large concentration gradients near the edge of the fire. This approach can quickly estimate potential dose from airborne radionuclides in wildland fire and assist decision-making to reduce firefighter exposure.

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