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 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.

Fuel load, structure, and potential fire behaviour in black spruce bogs

2015 ◽  
Vol 45 (7) ◽  
pp. 888-899 ◽  
Author(s):  
D.C. Johnston ◽  
M.R. Turetsky ◽  
B.W. Benscoter ◽  
B.M. Wotton
Keyword(s):  
High Intensity ◽  
Large Scale ◽  
Black Spruce ◽  
Fire Spread ◽  
Extreme Weather Events ◽  
Fuel Load ◽  
Fire Season ◽  
Future Climate Change ◽  
Organic Soils ◽  
Crown Fire

Boreal peatlands in Canada comprise a substantial store of soil organic carbon (peat), and this peat is vulnerable to extensive burning during periods of extended drying. Increased frequency of extreme weather events in boreal regions is expected with future climate change, and the conditions that would support sustained smouldering peat combustion within peatlands may be more common. Organic soils tend to burn by smouldering combustion, a very slow-moving process in fuels such as those found in peatlands. Thus the most extreme conditions for carbon loss to the atmosphere due to the burning of peat likely occur when widespread propagation of flaming combustion leads to widespread initiation of smouldering. To investigate the potential for large-scale, high-intensity fire spread across forested bogs, we examined the fuel conditions in forested bogs necessary to support active crown fire. We measured surface and canopy fine fuels (those available to contribute to the propagating energy flux of the main flaming front) across a postfire chronosequence of forested boreal bog from central Alberta, Canada. We found that fuel load of fine surface material remained relatively constant across the chronosequence and at levels large enough to support crown fire initiation. Black spruce (Picea mariana (Mill.) B.S.P.) regeneration begins to fill in the crown space with increasing time since disturbance and achieves crown bulk densities similar to black spruce upland forests. We estimated that after about 80 years, the black spruce canopy has developed enough available fuel to support active crown fire on between 10% to 40% of days in a typical fire season in central Alberta, Canada. Broad-scale propagation of high-intensity fire across a peatland when coincident with drought-induced lower moisture in deep peatland layers has the potential to lead to a substantial release of stored terrestrial carbon.

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 Long term effect of fire severity on carabid and lichen assemblages

2019 ◽  
Vol 2 ◽  
Author(s):  
Colin Bergeron ◽  
Dominique Arseneault
Keyword(s):  
Black Spruce ◽  
Fire Severity ◽  
Fire Behavior ◽  
Stem Density ◽  
Crown Fire ◽  
Fire Event ◽  
Bay Area ◽  
Density Area ◽  
Seed Mortality ◽  
In Fire

Variation in fire severity strongly influences post-fire forest development. The resulting fine scale forest heterogeneity could impact biodiversity over long periods after fire events. In the James Bay area of northern Québec, differential seed mortality caused by high and low crown fire severity resulted in dramatic variation in regeneration density of both jack pine and black spruce. Sixty years after such fire event, we show that composition of lichen and carabid assemblages varied significantly between areas of high (c. 2600 stems/ha) and low (c. 560 stems/ha) stem density established by differential crown fire severity. The carabids, Notiophilus semistriatus and Miscodera arctica, were found in low stem density areas while Carabus taedatus and Pterostichus brevicornis were found in high stem density areas. Amount of bare ground was higher in low stem density area which may favor active visual diurnal hunters such as Notiophilus species. Cladonia rangiferina and C. stellaris were associated with high stem density area while C. uncialis and C. mitis were associated with low stem density area. This likely reflects the fact that photosynthetic rate of C. rangiferina is optimal under shady areas whereas C. uncialis is better adapted to hot, dry and sunny conditions. Thus, variation in fire behavior led to long-lasting variation in forest conditions that clearly affected both lichen and carabid assemblages even 60 years after fire.

Characterisation of the fuel and fire environment in southern Ontario’s tallgrass prairie

2015 ◽  
Vol 24 (8) ◽  
pp. 1118 ◽  
Author(s):  
Susan Kidnie ◽  
B. Mike Wotton
Keyword(s):  
Moisture Content ◽  
Tallgrass Prairie ◽  
Prescribed Burning ◽  
Fire Spread ◽  
Fuel Load ◽  
Prairie Restoration ◽  
Prescribed Burn ◽  
Spread Rate ◽  
Prescribed Burns ◽  
Tallgrass Prairie Restoration

Prescribed burning can be an integral part of tallgrass prairie restoration and management. Understanding fire behaviour in this fuel is critical to conducting safe and effective prescribed burns. Our goal was to quantify important physical characteristics of southern Ontario’s tallgrass fuel complex prior to and during prescribed burns and synthesise our findings into useful applications for the prescribed fire community. We found that the average fuel load in tallgrass communities was 0.70 kg m–2. Fuel loads varied from 0.38 to 0.96 kg m–2. Average heat of combustion did not vary by species and was 17 334 kJ kg–1. A moisture content model was developed for fully cured, matted field grass, which was found to successfully predict moisture content of the surface layers of cured tallgrass in spring. We observed 25 head fires in spring-season prescribed burns with spread rates ranging from 4 to 55 m min–1. Flame front residence time averaged 27 s, varying significantly with fuel load but not fire spread rate. A grassland spread rate model from Australia showed the closest agreement with observed spread rates. These results provide prescribed-burn practitioners in Ontario better information to plan and deliver successful burns.

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.

Position of cones within cone clusters determines seed survival in black spruce during wildfire

2019 ◽  
Vol 49 (2) ◽  
pp. 121-127 ◽  
Author(s):  
T.B. Splawinski ◽  
D.F. Greene ◽  
S.T. Michaletz ◽  
S. Gauthier ◽  
D. Houle ◽  
...  
Keyword(s):  
Black Spruce ◽  
Seed Viability ◽  
Heat Fluxes ◽  
Wake Flow ◽  
Windward Side ◽  
Fire Intensity ◽  
Burned Area ◽  
Individual Plant ◽  
Buoyant Plumes ◽  
Porous Bodies

It has recently become clear that the regeneration density of serotinous species within a burned area declines with local fire intensity. It is assumed that this occurs because variation in local fire intensity leads to variation in incident heat fluxes and, ultimately, seed necrosis. We argue here that this same relationship between incident heat flux and seed necrosis is important at the scale of individual plant crowns. Using Picea mariana (Mill.) B.S.P. (black spruce), we show that postfire seed viability increases with crown height, depth into the crown, and angle from wind direction (with the windward side enjoying greater viability). All three effects are what one would expect given the physics of buoyant plumes, interactions of moving fire lines with wake flow around cylinders, and heat transfer in porous bodies such as a tree crown. We conclude by discussing the broader consequences of cone cluster size and global change on regeneration in serotinous species.

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 Splitting in Fire-Killed Trees in the Boreal Forest of Alberta

2003 ◽  
Vol 20 (4) ◽  
pp. 167-174
Author(s):  
Nobutaka Nakamura ◽  
Paul M. Woodard ◽  
Lars Bach
Keyword(s):  
Boreal Forest ◽  
Boreal Forests ◽  
Black Spruce ◽  
Lodgepole Pine ◽  
White Spruce ◽  
Balsam Fir ◽  
Crown Fire ◽  
In Fire ◽  
Solar Angle

Abstract Tree boles in the boreal forests of Alberta, Canada will split once killed by a stand-replacing crown fire. A total of 1,485 fire-killed trees were sampled, 1 yr after burning, in 23 plots in 14 widely separated stands within a 370,000 ha fire. Sampling occurred in the Upper and Lower Foothills natural subregions. The frequency of splitting varied by species but averaged 41% for all species. The order in the frequency of splitting was balsam fir, black spruce, white spruce and lodgepole pine. The type of splitting (straight, spiral, or multiple) varied by species, as did the position of the split on the tree bole. Aspect or solar angle was not statistically related to the type or occurrence of splitting.

Corrigendum to: Assessing canopy fuel stratum characteristics in crown fire prone fuel types of western North America

2010 ◽  
Vol 19 (1) ◽  
pp. iii ◽  
Author(s):  
Miguel G. Cruz ◽  
Martin E. Alexander ◽  
Ronald H. Wakimoto
Keyword(s):  
Ponderosa Pine ◽  
Fire Management ◽  
Linear Regression Analysis ◽  
Basal Area ◽  
Stand Density ◽  
Fuel Load ◽  
Tree Level ◽  
Management Decision ◽  
Crown Fire ◽  
In Fire

Application of crown fire behavior models in fire management decision-making have been limited by the difficulty of quantitatively describing fuel complexes, specifically characteristics of the canopy fuel stratum. To estimate canopy fuel stratum characteristics of four broad fuel types found in the western United States and adjacent areas of Canada, namely Douglas-fir, ponderosa pine, mixed conifer, and lodgepole pine forest stands, data from the USDA Forest Service's Forest Inventory and Analysis (FIA) database were analysed and linked with tree-level foliage dry weight equations. Models to predict canopy base height (CBH), canopy fuel load (CFL) and canopy bulk density (CBD) were developed through linear regression analysis and using common stand descriptors (e.g. stand density, basal area, stand height) as explanatory variables. The models developed were fuel type specific and coefficients of determination ranged from 0.90 to 0.95 for CFL, between 0.84 and 0.92 for CBD and from 0.64 to 0.88 for CBH. Although not formally evaluated, the models seem to give a reasonable characterization of the canopy fuel stratum for use in fire management applications.

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