Heat Content Variation of Sierra Nevada Conifers

1998 ◽  
Vol 8 (3) ◽  
pp. 147 ◽  
Author(s):  
JW Van Wagdendonk ◽  
WM Sydoriak ◽  
JM Benedict
Keyword(s):  
Developmental Stage ◽  
Sierra Nevada ◽  
Fire Behavior ◽  
Heat Content ◽  
Behavior Prediction ◽  
Fuel Component ◽  
Standard Values ◽  
Prediction Systems ◽  
Fine Fuels ◽  
In Fire

A study of fuels of Siena Nevada conifer species showed that percent ash content, heat content with ash, and heat content without ash of needle and duff fuels significantly varied by species, fuel component, and developmental stage of the overstory. Ash and heat contents of woody fuels varied by species and fuel component but not by developmental stage. Bark fuels significantly differed by species, while no factor significantly affected cone fuels. Regional variation in ash and heat content was evident but small. However, the values reported here for heat content with ash for fine fuels averaged 2.50 MJ kg-1 higher than the standard values used in fire behavior prediction systems. Using standard values can result in significant under predictions of fireline intensity of an average of 16 percent for all species of up to 47 percent for Pinus albicaulis.

scholarly journals Moisture Sorption Models for Fuel Beds of Standing Dead Grass in Alaska

Fire ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 2 ◽  
Author(s):  
Eric Miller
Keyword(s):  
Moisture Content ◽  
Equilibrium Moisture Content ◽  
Wildland Fire ◽  
Fire Behavior ◽  
Moisture Sorption ◽  
Field Measurements ◽  
Diurnal Changes ◽  
Behavior Prediction ◽  
Standing Dead ◽  
Prediction Systems

Sorption models were developed to predict the moisture content in fuelbeds of standing dead grass from ambient weather measurements. Intuition suggests that the response time of standing dead grass to diurnal changes in weather is negligible and that moisture content tracks the equilibrium moisture content under most field conditions. This assumption suggests that moisture content could be modelled by empirically fitting coefficients to equations of equilibrium moisture content using field measurements. Here, six equations commonly used in wildland fire management and other industries were fit using 293 measurements of weather and moisture content in standing dead grass from Alaska, U.S.A. Predictors were air temperature and either relative humidity or dewpoint depression. Mean absolute errors of the best three models were approximately 1.16% of moisture content. The models predicted well the moisture content of an independently collected dataset from Canada but less so a set from Australia. The models may be used in wildland fire danger rating and fire behavior prediction systems.

scholarly journals LiDAR-Based Estimates of Canopy Base Height for a Dense Uneven-Aged Structured Forest

2020 ◽  
Vol 12 (10) ◽  
pp. 1565 ◽  
Author(s):  
Alexandra Stefanidou ◽  
Ioannis Z. Gitas ◽  
Lauri Korhonen ◽  
Dimitris Stavrakoudis ◽  
Nikos Georgopoulos
Keyword(s):  
Regression Analysis ◽  
Wood Quality ◽  
Fire Behavior ◽  
Forest Health ◽  
Airborne Lidar ◽  
Forest Environment ◽  
Prediction Systems ◽  
Topographic Heterogeneity ◽  
In Fire ◽  
Airborne Lidar Data

Accurate canopy base height (CBH) information is essential for forest and fire managers since it constitutes a key indicator of seedling growth, wood quality and forest health as well as a necessary input in fire behavior prediction systems such as FARSITE, FlamMap and BEHAVE. The present study focused on the potential of airborne LiDAR data analysis to estimate plot-level CBH in a dense uneven-aged structured forest on complex terrain. A comparative study of two widely employed methods was performed, namely the voxel-based approach and regression analysis, which revealed a clear outperformance of the latter. More specifically, the voxel-based CBH estimates were found to lack correlation with the reference data ( R 2 = 0.15 , r R M S E = 42.36 % ) while most CBH values were overestimated resulting in an r b i a s of − 17.52 % . On the contrary, cross-validation of the developed regression model showcased an R 2 , r R M S E and r b i a s of 0 . 61 , 18.19 % and − 0.09 % respectively. Overall analysis of the results proved the voxel-based approach incapable of accurately estimating plot-level CBH due to vegetation and topographic heterogeneity of the forest environment, which however didn’t affect the regression analysis performance.

Role of vegetation and weather on fire behavior in the Canadian mixedwood boreal forest using two fire behavior prediction systems

2001 ◽  
Vol 31 (3) ◽  
pp. 430-441 ◽  
Author(s):  
Christelle Hély ◽  
Mike Flannigan ◽  
Yves Bergeron ◽  
Douglas McRae
Keyword(s):  
Boreal Forest ◽  
Full Range ◽  
Fire Behavior ◽  
Seasonal Effects ◽  
Fire Intensity ◽  
Fire Weather ◽  
Behavior Prediction ◽  
Prediction Systems ◽  
Mixedwood Boreal Forest

Spring and summer simulations were carried out using the Canadian Fire Behavior Prediction (FBP) and U.S. BEHAVE systems to study the role of vegetation and weather on fire behavior in the mixedwood boreal forest. Stands at Lake Duparquet (Quebec, Canada) were characterized as being deciduous, mixed-deciduous, mixed-coniferous, or coniferous, according to their conifer basal area percentage. Sampled fuel loads (litter, duff, woody debris, herbs, and shrubs) and local weather conditions (three different fire-risk classes) were used as inputs in the simulation. The predicted fire behavior variables were rate of spread (ROS), head fire intensity (HFI), and area burned. Results from ANOVA testing showed that both weather and vegetation are not always significant, and the two prediction systems qualitatively attribute the explained variance to these factors differently. The FBP System selects the weather factor as the most important factor for all fire behavior variables, whereas BEHAVE selects the vegetation factor. However, three research burns located in Ontario revealed that BEHAVE was not well adapted to the mixedwood boreal region, whereas FBP predictions were quantitatively close to observed prescribed values. Extreme fire weather is confirmed as producing large and intense fires, but differences in fire behavior among stand types exist across the full range of fire weather. Implications of climate change, vegetation, and seasonal effects on fire behavior and the forest mosaic are discussed.

Flashover and instabilities in fire behavior

1980 ◽  
Vol 38 ◽  
pp. 159-171 ◽  
Author(s):  
P.H. Thomas ◽  
M.L. Bullen ◽  
J.G. Quintiere ◽  
B.J. McCaffrey
Keyword(s):  
Fire Behavior ◽  
In Fire

Changes in fire behavior caused by fire exclusion and fuel build-up vary with topography in California montane forests, USA

2022 ◽  
Vol 304 ◽  
pp. 114255
Author(s):  
Catherine Airey-Lauvaux ◽  
Andrew D. Pierce ◽  
Carl N. Skinner ◽  
Alan H. Taylor
Keyword(s):  
Fire Behavior ◽  
Montane Forests ◽  
Fire Exclusion ◽  
In Fire

Numerical Analysis of Fire Behavior of a Large Space Pre-Stressed Steel Structure under Fire

2011 ◽  
Vol 71-78 ◽  
pp. 3729-3732
Author(s):  
Ming Zhou ◽  
Zhi Guo Xie ◽  
Xin Tang Wang
Keyword(s):  
Numerical Analysis ◽  
Fire Behavior ◽  
Thermal Response ◽  
Structural Response ◽  
Steel Structure ◽  
Large Space ◽  
Fire Source ◽  
Lattice Shell ◽  
In Fire ◽  
Influence Degree

The computational model of numerical analysis of a suspended pre-stressed steel reticulated shell subjected to fire load is established with using the software Marc. Based on the model presented here, numerical analysis of thermal response and structural response of the pre-stressed steel structure are computed. The different space height and different rise-span ratio are considered for analysis of response temperature, displacements and stresses of the pre-stressed lattice shell under fire for one fire source. It is also shown that displacement of the node right above the inner cable is the maximum among the four nodes presented here as the fire source is located at the position right below the second-ring cable of the structure. It is concluded that the influence degree of space height of the structure on the fire response of the structure is not great, but rise-span ratio has obvious and great effect on displacements and stresses of the pre-stressed steel structure with large span in fire.

Vegetation Fire Behavior Prediction in Russia

2020 ◽  
pp. 379-385
Author(s):  
Aleksandra V. Volokitina ◽  
Tatiana M. Sofronova ◽  
Mikhail A. Korets
Keyword(s):  
Fire Behavior ◽  
Behavior Prediction

scholarly journals Use of imaging spectroscopy and LIDAR to characterize fuels for fire behavior prediction

2018 ◽  
Vol 11 ◽  
pp. 41-50 ◽  
Author(s):  
E. Natasha Stavros ◽  
Janice Coen ◽  
Birgit Peterson ◽  
Harshvardhan Singh ◽  
Kama Kennedy ◽  
...  
Keyword(s):  
Imaging Spectroscopy ◽  
Fire Behavior ◽  
Behavior Prediction

Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest

2006 ◽  
Vol 15 (1) ◽  
pp. 37 ◽  
Author(s):  
Eric E. Knapp ◽  
Jon E. Keeley
Keyword(s):  
Sierra Nevada ◽  
Prescribed Burning ◽  
Fire Severity ◽  
Basal Area ◽  
Conifer Forest ◽  
Fuel Loading ◽  
Early Season ◽  
Late Season ◽  
Fuel Loads ◽  
In Fire

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.

scholarly journals The efficacy of fire and fuels reduction treatments in a Sierra Nevada pine plantation

2009 ◽  
Vol 18 (7) ◽  
pp. 791 ◽  
Author(s):  
Leda N. Kobziar ◽  
Joe R. McBride ◽  
Scott L. Stephens
Keyword(s):  
Sierra Nevada ◽  
Prescribed Fire ◽  
Large Scale ◽  
Structural Characteristics ◽  
Fire Behavior ◽  
Pine Plantation ◽  
Understorey Vegetation ◽  
Fuels Reduction ◽  
Reduction Techniques ◽  
Reducing Potential

Plantations are the most common means of reforestation following stand-replacing wildfires. As wildfires continue to increase in size and severity as a result of fire suppression or climate change, establishment of plantations will likely also increase. Plantations’ structural characteristics, including dense, uniform spacing and abundant ladder fuels, present significant wildfire hazards. Large-scale fuels reduction techniques may be necessary to reduce potential fire behavior in plantations and to protect surrounding forests. In the present study, four different manipulations aimed at reducing potential fire behavior in a Sierra Nevada pine plantation are compared. The treatments include: mechanical shredding, or mastication, of understorey vegetation and small trees; mastication followed by prescribed fire; fire alone; and controls. Fire behavior modeling shows that mastication is detrimental whereas prescribed fire is effective in reducing potential fire behavior at moderate to extreme weather conditions. Predicted fire behavior was compared with actual values from the prescribed burns in an effort to explore the limitations of fire modeling. Fire behavior predictions were similar to field observations in the more structurally homogeneous stands, but differed greatly where mastication created forest openings and patchy fuels distributions. In contrast to natural stands, the homogeneity of pine plantations make the results of the present work applicable to other regions such as the south-eastern US, where similar fuels reduction techniques are used to increase fire-resistance and stand resilience.

Sign in / Sign up

Export Citation Format

Share Document