scholarly journals Quantifying Stand Targets for Silvicultural Prevention of Crown Fires

2002 ◽  
Vol 17 (2) ◽  
pp. 101-109 ◽  
Author(s):  
Christopher R. Keyes ◽  
Kevin L. O'Hara
Keyword(s):  
Stand Structure ◽  
Fire Spread ◽  
Crown Fire ◽  
Fuel Management ◽  
Data Types ◽  
Crown Fires ◽  
Quantitative Basis ◽  
The Relationship ◽  
Stand Conditions ◽  
Forest Managers

Abstract Forest managers are expressing a growing interest in proactively reducing susceptibility to crown fires, but the quantitative basis for defining specific stand targets and prescribing silvicultural regimes for this objective is lacking. A procedure is presented for creating resistant stand structures that exploits the relationship between crown fire development and characteristics of stand structure. The BEHAVE surface fire model was integrated with modified versions of the Van Wagner crown ignition and crown fire spread equations in order to quantify structural targets for mitigative silvicultural practices. The procedure tolerates an array of input data types for weather, site, and surface fuel variables so that hazard-reducing guidelines are tailored to specific site and stand conditions. Suggested strategies for achieving crown fire-resistant stand targets include pruning, low thinning, and surface fuel management. West. J. Appl. For. 17(2):101–109.

Modelling the rate of fire spread and uncertainty associated with the onset and propagation of crown fires in conifer forest stands

2017 ◽  
Vol 26 (5) ◽  
pp. 413 ◽  
Author(s):  
Miguel G. Cruz ◽  
Martin E. Alexander
Keyword(s):  
Monte Carlo ◽  
Average Rate ◽  
Fire Spread ◽  
Prediction Errors ◽  
Crown Fire ◽  
Conifer Forest ◽  
Fire Behaviour ◽  
Crown Fires ◽  
Deterministic Modelling ◽  
Eastern Australia

Crown fires are complex, unstable phenomena dependent on feedback mechanisms between the combustion products of distinct fuel layers. We describe non-linear fire behaviour associated with crowning and the uncertainty they cause in fire behaviour predictions by running a semiphysical modelling system within a simple Monte Carlo simulation framework. The method was able to capture the dynamics of passive and active crown fire spread regimes, providing estimates of average rate of spread and the extent of crown fire activity. System outputs were evaluated against data collected from a wildfire that occurred in a radiata pine plantation in south-eastern Australia. The Monte Carlo method reduced prediction errors relative to the more commonly used deterministic modelling approach, and allowed a more complete description of the level of crown fire behaviour to expect. The method also provides uncertainty measures and probabilistic outputs, extending the range of questions that can be answered by fire behaviour models.

Variation in wind and crown fire behaviour in a northern jack pine – black spruce forest

2004 ◽  
Vol 34 (8) ◽  
pp. 1561-1576 ◽  
Author(s):  
S W Taylor ◽  
B M Wotton ◽  
M E Alexander ◽  
G N Dalrymple
Keyword(s):  
Black Spruce ◽  
Flame Temperature ◽  
Fire Spread ◽  
Crown Fire ◽  
Fire Behaviour ◽  
Canopy Layer ◽  
Crown Fires ◽  
Video Observations ◽  
Before And After ◽  
Fire Front

Fire spread and flame temperature were examined in a series of nine experimental crown fires conducted in the Northwest Territories, Canada. Average rates of spread were 17.8–66.8 m·min–1 (0.3–1.1 m·s–1) over burning periods from about 1.5–10 min across 75 m × 75 m to 150 m × 150 m plots. Detailed maps of fire front progression revealed areas with higher rates of spread in the order of tens of metres in horizontal dimension and tens of seconds in duration in several of the fires, which is consistent with the influence of coherent wind gusts. Comparison of open and in-stand wind speed before and after burning suggests that defoliation in the canopy layer during burning would result in the flaming zone having greater exposure to the ambient wind. Estimates of flame front residence from video observations at the surface averaged 34 s; estimates from temperature measurements decreased significantly with height from 74 s at the surface to 31 s below the canopy.

Relating flame radiation to home ignition using modeling and experimental crown fires

2004 ◽  
Vol 34 (8) ◽  
pp. 1616-1626 ◽  
Author(s):  
Jack D Cohen
Keyword(s):  
Forest Canopy ◽  
Severe Case ◽  
Fire Spread ◽  
Forest Plot ◽  
Crown Fire ◽  
Flame Radiation ◽  
Flame Heating ◽  
Crown Fires ◽  
Piloted Ignition ◽  
Fire Experiments

Wildland–urban fire destruction depends on homes igniting and thus requires an examination of the ignition requirements. A physical–theoretical model, based on severe case conditions and ideal heat transfer characteristics, estimated wood wall ignition occurrence from flame radiation heating and piloted ignition requirements. Crown fire experiments provided an opportunity for assessing model reliability. The crown fire experiments were specifically instrumented with wood wall sections and heat flux sensors to investigate direct flame heating leading to home ignition during wildland fires. The experimental results indicated that the flame radiation model overestimated the structure-to-flame distance that would result in wood wall ignition. Wall sections that ignited during the experimental crown fires did not sustain flaming after crown fire burnout. The experiments also revealed that the forest canopy attenuated the flame radiation as the crown fire spread within the forest plot. Ignition modeling and the associated crown fire experiments described the flame-to-structure distance scale associated with flame heating related to wall ignition.

A radiation-driven model for crown fire spread

2004 ◽  
Vol 34 (8) ◽  
pp. 1588-1599 ◽  
Author(s):  
B W Butler ◽  
M A Finney ◽  
P L Andrews ◽  
F A Albini
Keyword(s):  
Closed Form ◽  
A Priori ◽  
Radiant Energy ◽  
Fire Spread ◽  
Crown Fire ◽  
Spread Rate ◽  
Fire Modelling ◽  
Crown Fires ◽  
Environment Variables ◽  
Fire Front

A numerical model for the prediction of the spread rate and intensity of forest crown fires has been developed. The model is the culmination of over 20 years of previously reported fire modeling research and experiments; however, it is only recently that it has been formulated in a closed form that permits a priori prediction of crown fire spread rates. This study presents a brief review of the development and structure of the model followed by a discussion of recent modifications made to formulate a fully predictive model. The model is based on the assumption that radiant energy transfer dominates energy exchange between the fire and unignited fuel with provisions for convective cooling of the fuels ahead of the fire front. Model predictions are compared against measured spread rates of selected experimental fires conducted during the International Crown Fire Modelling Experiment. Results of the comparison indicate that the closed form of the model accurately predicts the relative response of fire spread rate to fuel and environment variables but overpredicts the magnitude of fire spread rates.

scholarly journals Crown structure of Picea omorika trees in the plantation

2012 ◽  
Vol 64 (2) ◽  
pp. 605-611 ◽  
Author(s):  
M. Krstic ◽  
N. Stavretovic ◽  
V. Isajev ◽  
I. Bjelanovic
Keyword(s):  
Tree Height ◽  
Tree Crown ◽  
Crown Length ◽  
Crown Structure ◽  
Parabolic Function ◽  
Picea Omorika ◽  
Serbian Spruce ◽  
The Relationship ◽  
Total Tree ◽  
Stand Conditions

The study was carried out in Serbian spruce (Picea omorika Panc/Purkyn?) plantations in the western Serbia. The paper presents results of the analysis of crown development. The following elements were analyzed: total tree height, height of the crown base, absolute and relative crown length, maximal crown diameter, coefficient of crown spreading and degree of crown girth. We discuss approaches to the modeling of tree crown growth and development, growing under favorable environmental and stand conditions, without anomalies in development. In order to establish the relationship between analyzed factors, regression analyses were applied. Data fitting was by the analytic method, by the implementation of Prodan?s functions of growth, linear and parabolic function. Received models can be used for the simulation of various growth and developing processes in forest.

Instantaneous spatio-temporal rate of spread of fast spreading wildfires - a new approach from visible and thermal image processing

2021 ◽  
Author(s):  
Benjamin Schumacher ◽  
Katharine Melnik ◽  
Marwan Katurji ◽  
Veronica Clifford ◽  
Jiawei Zhang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
New Zealand ◽  
Stand Structure ◽  
Fire Severity ◽  
Thermal Infrared ◽  
Fire Spread ◽  
New Approach ◽  
Rate Of Spread ◽  
Fast Spreading ◽  
Fire Experiments

<p>The rate of spread (ROS) of wildfires is an important parameter for understanding fire-atmospheric interactions and developing fire-spread models, but it is also vital for firefighting operations to ensure the safety of firefighters (Plucinski 2017, Stow 2019). Spatial ROS observations are usually carried out by using visible and thermal satellite imagery of wildfires estimating the ROS on a time scale of hours to days for large fires (>100 ha) or repeated passing with an airborne thermal infrared imager for higher spatial and temporal resolution (Viedma et al. 2015, Stow 2014). For fire experiments in highly controlled conditions like laboratory fires or during light fuel prescribed burns, ROS estimation usually involves lag-correlation of temperature point measurements (Finney 2010, Johnston 2018). However, these methodologies are not applicable to fast-spreading grass or bush fires because of their temporal and spatial limitations. Instantaneous spatial ROS of these fires is needed to understand rapid changes in connection with the three major drivers of the fire: fuel, topography and atmospheric forcings.</p><p>We are presenting a new approach towards a spatial ROS product which includes newly developed image tracking methods based on thermal and visible imagery collected from unmanned aerial vehicles to estimate instantaneous, spatial ROS of fast spreading grass or bush fires. These techniques were developed using imagery from prescribed wheat-stubble burns carried out in Darfield, New Zealand in March 2018 (Finney 2018). Results show that both the visible and thermal tracking techniques produce similar mean ROS; however they differ in limitations and advantages. The visible-spectrum tracking method clearly identifies the flaming zone and provides accurate ROS measurements especially at the fire front. The thermal tracking technique is superior when resolving dynamics and ROS within the flaming zone because it resolves smaller scale structures within the imagery.</p><p> </p><p>References:</p><p>Finney, M. et al. 2010: An Examination of Fire Spread Thresholds in Discontinuous Fuel Beds.” International Journal of Wildland Fire, 163–170.</p><p>Finney, M. et al. 2018: New Zealand prescribed fire experiments to test convective heat transfer in wildland fires. In Advances in Forest Fire Research, Imprensa da Universidade de Coimbra: Coimbra, 2018.</p><p>Johnston, J. M., et al. 2018:  Flame-Front Rate of Spread Estimates for Moderate Scale Experimental Fires are Strongly Influenced by Measurement Approach. Fire 1: 16–17</p><p>Plucinski M., et al. 2017: Improving the reliability and utility of operational bushfire behaviour predictions in Australian vegetation. Environmental Modelling & Software 91, 1-12.</p><p>Stow, D., et al. 2014: Measuring Fire Spread Rates from Repeat PassAirborne Thermal Infrared Imagery. Remote Sensing Letters 5: 803–881.</p><p>Stow, D., et al. 2019: Assessing uncertainty and demonstrating potentialfor estimating fire rate of spread at landscape scales based on time sequential airbornethermal infrared imaging, International Journal of Remote Sensing, 40:13, 4876-4897</p><p>Viedma, O., et al. 2015:  Fire Severity in a Large Fire in a Pinus Pinaster Forest Is Highly Predictable from Burning Conditions, Stand Structure, and Topography. Ecosystems18: 237–250.</p>

Project Vesta: Fire in Dry Eucalypt Forest

2008 ◽  
Author(s):  
JS Gould ◽  
WL McCaw ◽  
NP Cheney ◽  
PF Ellis ◽  
IK Knight ◽  
...  
Keyword(s):  
Wind Speed ◽  
Fire Spread ◽  
Fire Behaviour ◽  
Understorey Vegetation ◽  
Eucalypt Forest ◽  
Age Related ◽  
Vegetation Structures ◽  
Eucalypt Forests ◽  
The Relationship ◽  
New Algorithms

Project Vesta was a comprehensive research project to investigate the behaviour and spread of high-intensity bushfires in dry eucalypt forests with different fuel ages and understorey vegetation structures. The project was designed to quantify age-related changes in fuel attributes and fire behaviour in dry eucalypt forests typical of southern Australia. The four main scientific aims of Project Vesta were: To quantify the changes in the behaviour of fire in dry eucalypt forest as fuel develops with age (i.e. time since fire); To characterise wind speed profiles in forest with different overstorey and understorey vegetation structure in relation to fire behaviour; To develop new algorithms describing the relationship between fire spread and wind speed, and fire spread and fuel characteristics including load, structure and height; and to develop a National Fire Behaviour Prediction System for dry eucalypt forests. These aims have been addressed through a program of experimental burning and associated studies at two sites in the south-west of Western Australia.

Simulated fire behaviour in young, postfire lodgepole pine forests

2017 ◽  
Vol 26 (10) ◽  
pp. 852 ◽  
Author(s):  
Kellen N. Nelson ◽  
Monica G. Turner ◽  
William H. Romme ◽  
Daniel B. Tinker
Keyword(s):  
Pinus Contorta ◽  
Stand Structure ◽  
Lodgepole Pine ◽  
Pine Forests ◽  
Fuel Moisture ◽  
Crown Fire ◽  
Fire Behaviour ◽  
Fire Initiation ◽  
Moisture Conditions ◽  
Simulated Fire

Early-seral forests are expanding throughout western North America as fire frequency and annual area burned increase, yet fire behaviour in young postfire forests is poorly understood. We simulated fire behaviour in 24-year-old lodgepole pine (Pinus contorta var. latifolia) stands in Yellowstone National Park, Wyoming, United States using operational models parameterised with empirical fuel characteristics, 50–99% fuel moisture conditions, and 1–60kmhr−1 open winds to address two questions: [1] How does fireline intensity, and crown fire initiation and spread vary among young, lodgepole pine stands? [2] What are the contributions of fuels, moisture and wind on fire behaviour? Sensitivity analysis indicated the greatest contributors to output variance were stand structure mediated wind attenuation, shrub fuel loads and 1000-h fuel moisture for fireline intensity; crown base height for crown fire initiation; and crown bulk density and 1-h fuel moisture for crown fire spread. Simulation results predicted crown fire (e.g. passive, conditional or active types) in over 90% of stands at 50th percentile moisture conditions and wind speeds greater than 3kmhr−1. We conclude that dense canopy characteristics heighten crown fire potential in young, postfire lodgepole pine forests even under less than extreme wind and fuel moisture conditions.

Effect of thinning and prescribed burning on crown fire severity in ponderosa pine forests

2002 ◽  
Vol 11 (1) ◽  
pp. 1 ◽  
Author(s):  
Jolie Pollet ◽  
Philip N. Omi
Keyword(s):  
Prescribed Fire ◽  
Ponderosa Pine ◽  
Stand Structure ◽  
Fire Severity ◽  
Fire Effects ◽  
Pine Forests ◽  
Crown Fire ◽  
Fuel Treatments ◽  
Ponderosa Pine Forests ◽  
Wildfire Hazard

Fire exclusion policies have affected stand structure and wildfire hazard in north American ponderosa pine forests. Wildfires are becoming more severe in stands where trees are densely stocked with shade-tolerant understory trees. Although forest managers have been employing fuel treatment techniques to reduce wildfire hazard for decades, little scientific evidence documents the success of treatments in reducing fire severity. Our research quantitatively examined fire effects in treated and untreated stands in western United States national forests. Four ponderosa pine sites in Montana, Washington, California and Arizona were selected for study. Fuel treatments studied include: prescribed fire only, whole-tree thinning, and thinning followed by prescribed fire. On-the-ground fire effects were measured in adjacent treated and untreated forests. We developed post facto fire severity and stand structure measurement techniques to complete field data collection. We found that crown fire severity was mitigated in stands that had some type of fuel treatment compared to stands without any treatment. At all four of the sites, the fire severity and crown scorch were significantly lower at the treated sites. Results from this research indicate that fuel treatments, which remove small diameter trees, may be beneficial for reducing crown fire hazard in ponderosa pine sites.

Prescribed fire as a tool to regenerate live and dead serotinous jack pine (Pinus banksiana) stands

2017 ◽  
Vol 26 (6) ◽  
pp. 478 ◽  
Author(s):  
Maria Sharpe ◽  
Hyejin Hwang ◽  
David Schroeder ◽  
Soung Ryoul Ryu ◽  
Victor J. Lieffers
Keyword(s):  
Prescribed Fire ◽  
Natural Regeneration ◽  
Pinus Banksiana ◽  
Mountain Pine Beetle ◽  
Jack Pine ◽  
Crown Fire ◽  
Seedling Regeneration ◽  
Dead Trees ◽  
Crown Fires ◽  
Pine Beetle

This study documents cone opening and natural regeneration of jack pine (Pinus banksiana Lamb.) after burning live and dead stands similar to those killed by the mountain pine beetle (Dendroctonus ponderosae). Trees were killed by girdling in May and were burned in late July, 26 months later. Pairs of live and dead plots were simultaneously burned using three types of fire: surface, intermittent crown and continuous crown fires. Each type of fire was replicated three times; the nine pairs of burns were completed in a 4-day period. After fire, more cones were opened on dead trees than live trees. On dead trees, there was cone opening even when fire charred only the lower part of the bole. Three years after burning, dead stands with continuous crown fires had some of the densest regeneration and the highest rates of stocking. Across all burns in this study, seedling regeneration was best in shallow residual duff and in the more intensely burned plots. Without burning, there was virtually no regeneration 5 years after mortality. The results also show that burning, especially under continuous crown fire, could be used to promote regeneration in dead stands.

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