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 Assessment of the Characteristics of Recent Major Wildfires in the USA, Australia and Brazil in 2018–2019 Using Multi-Source Satellite Products

2020 ◽  
Vol 12 (11) ◽  
pp. 1803 ◽  
Author(s):  
Mahlatse Kganyago ◽  
Lerato Shikwambana
Keyword(s):  
Forest Cover ◽  
Anthropogenic Activities ◽  
Management Strategies ◽  
Environmental Parameters ◽  
Fuel Load ◽  
Fire Intensity ◽  
Burned Area ◽  
Radiative Power ◽  
The Usa ◽  
Moderate Resolution Imaging Spectroradiometer

This study analysed the characteristics of the recent (2018–2019) wildfires that occurred in the USA, Brazil, and Australia using Moderate Resolution Imaging Spectroradiometer (MODIS) active fires (AF), fire radiative power (FRP, MW) and burned area (BA) products. Meteorological and environmental parameters were also analysed. The study found various patterns in the spatial distribution of fires, FRP and BA at the three sites, associated with various vegetation compositions, prevailing meteorological and environmental conditions and anthropogenic activities. We found significant fire clusters along the western and eastern coasts of the USA and Australia, respectively, while vastly distributed clusters were found in Brazil. Across all sites, significant fire intensity was recorded over forest cover (FC) and shrublands (SL), attributed to highly combustible tree crown fuel load characterised by leafy canopies and thin branches. In agreement, BA over FC was the highest in the USA and Australia, while Brazil was dominated by the burning of SL, characteristic of fire-tolerant Cerrado. The relatively lower BA over FC in Brazil can be attributed to fuel availability and proximity to highly flammable cover types such as cropland, SL and grasslands rather than fuel flammability. Overall, this study contributes to a better understanding of wildfires in various regions and the underlying environmental and meteorological causal factors, towards better wildfire disaster management strategies and habitat-specific firefighting.

Soil organic layer combustion in boreal black spruce and jack pine stands of the Northwest Territories, Canada

2018 ◽  
Vol 27 (2) ◽  
pp. 125 ◽  
Author(s):  
Xanthe J. Walker ◽  
Jennifer L. Baltzer ◽  
Steven G. Cumming ◽  
Nicola J. Day ◽  
Jill F. Johnstone ◽  
...  
Keyword(s):  
Northwest Territories ◽  
Boreal Forests ◽  
Black Spruce ◽  
Jack Pine ◽  
Fire Intensity ◽  
Organic Layer ◽  
Complete Combustion ◽  
Soil Organic Layer ◽  
Pine Stands ◽  
Burn Depth

Increased fire frequency, extent and severity are expected to strongly affect the structure and function of boreal forest ecosystems. In this study, we examined 213 plots in boreal forests dominated by black spruce (Picea mariana) or jack pine (Pinus banksiana) of the Northwest Territories, Canada, after an unprecedentedly large area burned in 2014. Large fire size is associated with high fire intensity and severity, which would manifest as areas with deep burning of the soil organic layer (SOL). Our primary objectives were to estimate burn depth in these fires and then to characterise landscapes vulnerable to deep burning throughout this region. Here we quantify burn depth in black spruce stands using the position of adventitious roots within the soil column, and in jack pine stands using measurements of burned and unburned SOL depths. Using these estimates, we then evaluate how burn depth and the proportion of SOL combusted varies among forest type, ecozone, plot-level moisture and stand density. Our results suggest that most of the SOL was combusted in jack pine stands regardless of plot moisture class, but that black spruce forests experience complete combustion of the SOL only in dry and moderately well-drained landscape positions. The models and calibrations we present in this study should allow future research to more accurately estimate burn depth in Canadian boreal forests.

Postfire seed rain of black spruce, a semiserotinous conifer, in forests of interior Alaska

2009 ◽  
Vol 39 (8) ◽  
pp. 1575-1588 ◽  
Author(s):  
Jill Johnstone ◽  
Leslie Boby ◽  
Emily Tissier ◽  
Michelle Mack ◽  
Dave Verbyla ◽  
...  
Keyword(s):  
Structural Equation ◽  
Black Spruce ◽  
Fire Severity ◽  
Seed Viability ◽  
Basal Area ◽  
Seed Rain ◽  
Equation Modeling ◽  
Viable Seed ◽  
Interior Alaska ◽  
Total Seed

The availability of viable seed can act as an important constraint on plant regeneration following disturbance. This study presents data on seed quantity and quality for black spruce ( Picea mariana (Mill.) B.S.P.), a semiserotinous conifer that dominates large areas of North American boreal forest. We sampled seed rain and viability for 2 years after fire (2005–2007) in 39 sites across interior Alaska that burned in 2004. All sites were dominated by black spruce before they burned. Structural equation modeling was used to assess the relative importance of prefire spruce abundance, topography effects, canopy fire severity, and distance to unburned stands in explaining variations in black spruce seed rain. Prefire basal area of spruce that remained standing after fire was a significant predictor of total seed rain, but seed viability was more strongly related to site elevation, canopy fire severity, and distances to unburned stands. Although positive relations between tree basal area and the size of the aerial seed bank may place a first constraint on seed availability, accurate prediction of postfire viable seed rain for serotinous conifers also requires consideration of the effects of abiotic stress and canopy fire severity on seed viability.

scholarly journals Prediction Equations for Black Spruce Seed Production and Dispersal in Northern Ontario

1982 ◽  
Vol 58 (2) ◽  
pp. 96-99 ◽  
Author(s):  
B. Payandeh ◽  
V. F. Haavisto
Keyword(s):  
Seed Production ◽  
Nonlinear Regression ◽  
Picea Mariana ◽  
Black Spruce ◽  
Seed Viability ◽  
Original Data ◽  
Regression Equations ◽  
Northern Ontario ◽  
Solution Of Equations ◽  
Number Of Seeds

Nonlinear regression equations were developed to describe seed production and dispersal in black spruce (Picea mariana [Mill.]B.S.P.)in northern Ontario. Solution of the equations can provide useful information beyond the range of the original data, because of the flexibility of the models used. For example, solution of equations 1-3 indicates that cones from intermediate crown class trees initially have about twice as many seeds as those of either the dominant or codominant trees, but disperse their seeds at a much faster rate. Average number of seeds per cone for all three crown classes is about 7 after 10 years. Older cones of the intermediate crown class trees have fewest seeds per cone. Solution of equation 4 indicates that average seed viability is about 53% and decreases only slightly during the first three years. It then decreases very rapidly up to 12 years to about 5%. Similarly, equations 6 and 7 may be solved to determine an optimum strip-cut width for sufficient seedfall across the strip to produce satisfactory regeneration.

scholarly journals Fire emission rates of NO<sub>x</sub> based on the empirical relationship between satellite-derived tropospheric NO<sub>2</sub> and fire radiative power

2013 ◽  
Vol 13 (11) ◽  
pp. 28453-28510
Author(s):  
S. F. Schreier ◽  
A. Richter ◽  
J. W. Kaiser ◽  
J. P. Burrows
Keyword(s):  
Atmospheric Chemistry ◽  
Empirical Relationship ◽  
Temporal Correlation ◽  
Fire Intensity ◽  
Burned Area ◽  
Emission Rates ◽  
Monthly Means ◽  
Radiative Power ◽  
The Tropics ◽  
Fire Radiative Power

Abstract. Nitrogen oxides (NOx) play key roles in atmospheric chemistry, air pollution, and climate. While the largest fraction of these reactive gases is released by anthropogenic emission sources, a significant amount can be attributed to vegetation fires. In this study, NO2 from GOME-2 on board EUMETSAT's MetOp-A and OMI on board NASA's Aura as well as fire radiative power (FRP) from the measurements of MODIS on board NASA's Terra and Aqua are used to derive fire emission rates (FERs) of NOx for different types of vegetation using a simple statistical approach. Monthly means of tropospheric NO2 vertical columns (TVC NO2) have been analyzed for their temporal correlation with the monthly means of FRP for five consecutive years from 2007 to 2011 on a horizontal 1° × 1° grid. The strongest correlation is found to be largely confined to tropical and subtropical regions, which account for more than 80% of yearly burned area on average globally. In these regions, the seasonal variation of fire intensity, expressed by the FRP data, is similar to the pattern of TVC NO2. As chemical models typically require values for the amount of NOx being released as a function of time, we have converted the retrieved TVC NO2 into production rates of NOx from fire (Pf) by assuming a constant lifetime of NOx. The comparison between Pf and NOx emissions from GFEDv3.1 over 5 characteristic biomass burning regions in the tropics and subtropics indicated good agreement. By separating the monthly means of Pf and FRP according to land cover type, FERs of NOx could be derived for different biomes. The estimated FERs for the dominating types of vegetation burned are lowest for open shrublands and savannas (0.28–1.03 g NOx s−1 MW−1) and highest for croplands and woody savannas (0.82–1.56 g NOx s−1 MW−1). This analysis demonstrates clearly that there are biome-specific, diurnal, and regional differences in FERs for the dominating types of vegetation burned in the tropics and subtropics. Possible factors affecting the magnitude of the obtained values are discussed.

Fire and substrate interact to control the northern range limit of black spruce (Picea mariana) in Alaska

2007 ◽  
Vol 37 (12) ◽  
pp. 2480-2493 ◽  
Author(s):  
Andrea H. Lloyd ◽  
Christopher L. Fastie ◽  
Hilary Eisen
Keyword(s):  
Sexual Reproduction ◽  
Picea Mariana ◽  
Fire History ◽  
Black Spruce ◽  
Seed Viability ◽  
Range Limit ◽  
Acidic Soils ◽  
Eastern Canada ◽  
Substrate Effects ◽  
Northern Range Limit

Black spruce ( Picea mariana (Mill.) BSP) is a common treeline species in eastern Canada but rare at treeline in Alaska. We investigated fire and substrate effects on black spruce populations at six sites along a 74 km transect in the Brooks Range, Alaska. Our southern sites, on a surface deglaciated >50 000 years ago, had significantly more acidic soils, more black spruce, and higher seed viability than our northern sites, which were deglaciated approximately 13 000 years ago. Despite similar fire history at five of our six sites, postfire recruitment dynamics varied with surface age. Sexual reproduction was vigorous in both postfire and nonfire years in populations on the older surface. On the younger surface, vigorous sexual reproduction was restricted to postfire decades and clonal reproduction by branch layering predominated in nonfire years. At the northernmost site, which was unburned, black spruce reproduced almost exclusively by layering. The species’ northern range limit thus reflects an interaction between fire and substrate: on recently deglaciated surfaces, sexual reproduction is restricted to postfire years. This substrate-induced dependence on fire may restrict the range of black spruce to sites that burn sufficiently often to allow occasional sexual reproduction.

scholarly journals Examination of effects of aerosols on a pyroCb and their dependence on fire intensity and aerosol perturbation

2020 ◽  
Vol 20 (6) ◽  
pp. 3357-3371
Author(s):  
Seoung Soo Lee ◽  
George Kablick III ◽  
Zhanqing Li ◽  
Chang Hoon Jung ◽  
Yong-Sang Choi ◽  
...  
Keyword(s):  
Water Vapor ◽  
Heat Fluxes ◽  
Cirrus Clouds ◽  
Fire Intensity ◽  
Modeling Framework ◽  
Surface Heat Fluxes ◽  
Cloud Properties ◽  
Aerosol Effect ◽  
Weak Intensity ◽  
Weak Surface

Abstract. Using a modeling framework, this study investigates how a pyrocumulonimbus (pyroCb) event influences water vapor concentrations and cirrus-cloud properties near the tropopause, specifically focusing on how fire-produced aerosols affect this role. Results from a case study show that when observed fire intensity is high, there is an insignificant impact of fire-produced aerosols on the development of the pyroCb and associated changes in water vapor and cirrus clouds near the tropopause. However, as fire intensity weakens, effects of those aerosols on microphysical variables and processes such as droplet size and autoconversion increase. Due to this, aerosol-induced invigoration of convection is significant for pyroCb with weak-intensity fires and associated weak surface heat fluxes. This leads to a situation where there is a greater aerosol effect on the transport of water vapor to the upper troposphere and the production of cirrus clouds with weak-intensity fires, whereas this effect is muted with strong-intensity fires.

scholarly journals The empirical relationship between satellite-derived tropospheric NO<sub>2</sub> and fire radiative power and possible implications for fire emission rates of NO<sub>x</sub>

2014 ◽  
Vol 14 (5) ◽  
pp. 2447-2466 ◽  
Author(s):  
S. F. Schreier ◽  
A. Richter ◽  
J. W. Kaiser ◽  
J. P. Burrows
Keyword(s):  
Empirical Relationship ◽  
Fire Intensity ◽  
Burned Area ◽  
Emission Rates ◽  
Monthly Means ◽  
Fire Emissions ◽  
Vegetation Fires ◽  
Radiative Power ◽  
The Tropics ◽  
Fire Radiative Power

Abstract. Nitrogen oxides (NOx) play key roles in atmospheric chemistry, air pollution, and climate. While the largest fraction of these reactive gases is released by anthropogenic emission sources, a significant amount can be attributed to vegetation fires. In this study, NO2 from GOME-2 on board EUMETSAT's MetOp-A and OMI on board NASA's Aura as well as fire radiative power (FRP) from the measurements of MODIS on board NASA's Terra and Aqua satellites are used to derive fire emission rates (FERs) of NOx for different types of vegetation using a simple statistical approach. Monthly means of tropospheric NO2 vertical columns (TVC NO2) have been analyzed for their temporal correlation with the monthly means of FRP for five consecutive years from 2007 to 2011 on a horizontal 1° × 1° grid. The strongest correlation is found to be largely confined to tropical and subtropical regions, which account for more than 80% of yearly burned area, on average, globally. In these regions, the seasonal variation of fire intensity, expressed by the FRP data, is similar to the pattern of TVC NO2. As chemical models typically require values for the amount of NOx being released as a function of time, we have converted the retrieved TVC NO2 into production rates of NOx from fire (Pf) by assuming a constant lifetime of NOx. The comparison between Pf and NOx emissions from the Global Fire Emissions Database (GFEDv3.1) over 5 characteristic biomass burning regions in the tropics and subtropics shows good agreement. By separating the monthly means of Pf and FRP according to land cover type, FERs of NOx could be derived for different biomes. The estimated FERs for the dominating types of vegetation burned are lowest for open shrublands and savannas (0.28–1.03 g NOx s−1 MW−1) and highest for croplands and woody savannas (0.82–1.56 g NOx s−1 MW−1). This analysis demonstrates that the strong empirical relationship between TVC NO2 and FRP and the following simplified assumptions are a useful tool for the characterization of NOx emission rates from vegetation fires in the tropics and subtropics. Possible factors affecting the magnitude of the obtained values are discussed.

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