scholarly journals Firebrand Generation Rates at the Source for Trees and a Shrub

2021 ◽  
Vol 7 ◽  
Author(s):  
Sampath Adusumilli ◽  
James E. Chaplen ◽  
David L. Blunck
Keyword(s):  
Moisture Content ◽  
Wind Direction ◽  
Ponderosa Pine ◽  
Fire Spread ◽  
Dry Mass ◽  
Douglas Fir ◽  
Extrapolation Method ◽  
Source Terms ◽  
First Order

Source terms of the number of firebrands released as trees/shrubs torch are essential for helping to more accurately implement detailed physics-based models of wildfire propagation, particularly when torching occurs. A key challenge in estimating these source terms is the difficulty in measuring firebrand generation rates from the source. Typical studies have reported generation characteristics (firebrands/m2), but enumeration of the total number of firebrands released has remained elusive. Recently, a fire-resistant fabric was successfully employed to quantify “hot” firebrands (i.e., can potentially lead to further fire spread) generated during tree-scale burns. In this paper, a total of 71 tree/shrubs were burned to quantify hot firebrand production statistics for Douglas-fir, ponderosa pine, and sagebrush. A network of 65 fire-resistant fabric stations were deployed during the burns to measure the “hot” firebrands that are released. These stations are placed strategically at several radii and angles in the prominent wind direction. Using the number of firebrands determined from the fabric, a first-order extrapolation method was developed and evaluated to estimate the source terms (i.e., total number of hot firebrands released). Variation in the firebrand production with the height of the trees and for three species is reported. The total number of hot firebrands produced typically increased with the height of the tree/shrub burned as expected. The specific hot firebrand production (firebrands produced per kg dry mass burned) is exponentially dependent on the moisture content of the tree and had an inconclusive correlation with the height of the trees. Overall, for trees of comparable moisture content, sagebrush produced higher specific hot firebrands when compared to ponderosa pine and Douglas-fir species.

scholarly journals Effect of Prescribed Burning at Different Fuel Moisture Levels on Grasslands in Wind Cave National Park

1979 ◽  
Vol 3 ◽  
pp. 148-152
Author(s):  
F. Gartner ◽  
E. White ◽  
L. Worcester
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
National Park ◽  
Prescribed Burning ◽  
Fire Spread ◽  
Control Treatment ◽  
Grass Species ◽  
Fuel Moisture

The study was designed to determine whether different fuel and soil moisture levels at time of ignition would alter the response of key grass species to prescribed burning. Grasslands occupy approximately 75% of the area of Wind Cave National Park (WCNP); the remainder is dominated by ponderosa pine (Pinus ponderosa), according to Lovass (1973). The Soil Conservation Service (1969) classed only about 17% of the Park area as woodland. Nearly all grassland adjacent to woodland has been invaded by ponderosa pine. Almost without exception, pine invades the little bluestem - big bluestem (Schizachyrium scorparium - Andropogon gerardi) community, but not the wheatgrass - needle-grass - grama (Andropogon - Stipa- Bouteloua) community. While these two communities are frequently interspersed, the bluestem community probably occupies the largest percentage of the total grassland area. The general relationships between fuel moisture content and fire spread (or ease of control) are well known. However, relationships between fuel and surface soil moisture content and responses of plant species to burning are not well documented. Since the key grass species of the bluestem community are major dominants throughout the Park, that community was selected for the study. Examined were the effects of three fuel moisture levels (dry, medium and wet) at ignition on postburn species composition, cover, height, weight, soil moisture and soil chemistry. The design also included an unburned (control) treatment.

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.

scholarly journals Douglas Fir and Ponderosa Pine Seed Dormancy as Regulated by Grassland Seedbed Conditions

2004 ◽  
Vol 57 (6) ◽  
pp. 661 ◽  
Author(s):  
Yuguang Bai ◽  
Don Thompson ◽  
Klaas Broersma
Keyword(s):  
Seed Dormancy ◽  
Ponderosa Pine ◽  
Douglas Fir

scholarly journals Growth analysis of sweet pepper cultivated in coconut fiber in a greenhouse

2011 ◽  
Vol 29 (3) ◽  
pp. 316-323 ◽  
Author(s):  
Hamilton César de O Charlo ◽  
Sueyde F de Oliveira ◽  
Renata Castoldi ◽  
Pablo F Vargas ◽  
Leila T Braz ◽  
...  
Keyword(s):  
Growth Analysis ◽  
Dry Mass ◽  
Sweet Pepper ◽  
Absolute Rate ◽  
Coconut Fiber ◽  
First Order ◽  
Growth Production ◽  
Four Blocks ◽  
Over Time

Knowledge about the growth of crops allows the planning of rational cultivation methods which contribute to achieve greater potential of plant species, besides supplying information for the construction of descriptive mathematical models of growth. The growth curve of sweet pepper (Eppo hybrid), cultivated in coconut fiber in a greenhouse with fertirrigation, was determined. The experiment consisted initially of 160 plants divided into four blocks. Two plants were analyzed per block every 21 days after transplanting, ending at 189 days after transplant. The cultivation was carried out in plastics pots of 13 L containing coconut fiber, which were arranged in double rows, spaced 0.5 x 0.8 m between simple rows and 1.1 m between double rows. In each harvest the plant growth, production and quality of mature fruits were evaluated. The dry mass of the shoot increased with time, following the experimental model exponential of first order, reaching a maximum of 451.5 g/plant, 189 days after transplanting (DAT). The production of dry mass of leaves, stem, root and fruit also increased over time reaching maximum values of 68.7, 65.8, 11.5 and 302.9 g/plant, respectively, at 189 DAT. The same occurred with the leaf area per plant, plant height and the absolute rate of growth, whose maximum values were 6.183,5 cm², 136.9 cm and 4.4 g/plant/day, respectively. The growth of the plant was continuous throughout the cycle, and the highest amount of dry mass was accumulated in fruits, reaching a marketable production of 97.3 t ha-1. All fruits were classified as Extra.

Nutrient and hormone levels in Douglas-fir corrosion cavities, megagametophytes, and embryos during embryony

2005 ◽  
Vol 35 (10) ◽  
pp. 2447-2456 ◽  
Author(s):  
John G Carman ◽  
Gordon Reese ◽  
Rodney J Fuller ◽  
Timnit Ghermay ◽  
Roger Timmis
Keyword(s):  
Pseudotsuga Menziesii ◽  
Dry Mass ◽  
Douglas Fir ◽  
Chemical Analyses ◽  
Dynamic Changes ◽  
Hormone Levels ◽  
Corrosion Cavity ◽  
Novel Method ◽  
Indole 3 Acetic Acid

Gymnospermous embryos are nourished by fluids secreted from the megagametophyte. During early embryony, these fluids occupy the newly formed corrosion cavity. We describe a novel method for extracting corrosion cavity fluid and provide chemical analyses based on extractions from approximately 120 000 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) megagametophytes. Levels of potassium, phosphorus, calcium, zinc, and iron were higher in corrosion cavity fluid than in whole tissue, but levels of sulphur and manganese were lower. Levels of cyclitols, sucrose equivalents, erythrose, and arabinose were many-fold higher in corrosion cavity fluid than in whole tissues. Ala, Ser, Arg, Glx, and NH3 exceeded 80 mmol/kg dry mass in corrosion cavity fluid. These levels were about 100-fold higher than those found in whole tissues. During early embryony, hormone levels in corrosion cavity fluid were higher than levels observed in whole megagametophytes by 120-fold for indole-3-acetic acid, 53-fold for abscisic acid, and 8- to 10-fold for cytokinins. Nutrient and hormone levels tended to be much higher in the corrosion cavity fluid than would have been predicted based on whole-tissue analyses. Dynamic changes in nutrient and hormone levels occurred over time in the corrosion cavity, and these changes may normalize embryony in situ.

scholarly journals Campomanesia adamantium (Cambess.) O. Berg seed desiccation: influence on vigor and nucleic acids

2015 ◽  
Vol 87 (4) ◽  
pp. 2217-2228 ◽  
Author(s):  
DAIANE M. DRESCH ◽  
TATHIANA E. MASETTO ◽  
SILVANA P.Q. SCALON
Keyword(s):  
Moisture Content ◽  
Silica Gel ◽  
Primary Root ◽  
Dry Mass ◽  
Rna Integrity ◽  
Laboratory Conditions ◽  
Dna And Rna ◽  
Seed Desiccation ◽  
Seedling Length ◽  
Activated Silica Gel

The aim of this study was to evaluate the sensitivity of Campomanesia adamantium seeds to desiccation by drying in activated silica gel (fast) and under laboratory conditions (slow). To assess the sensitivity of the seeds to desiccation, we used drying with silica gel and drying under laboratory conditions (25 °C), in order to obtain seeds with moisture content of 45, 35, 30, 25, 20, 15, 10 and 5%. The physiological potential of the seeds after desiccation was evaluated by measuring primary root protrusion, percentage of normal seedlings, germination seed index, seedling length, total seedling dry mass, electrical conductivity and DNA and RNA integrities. The C. adamantium seeds were sensitive to desiccation and to a reduction in moisture content to 21.1% or less by desiccation using silica gel, and to 17.2% or less by desiccation under laboratory conditions; impairment of the physiological potential of the seeds was observed at these low moisture content levels. The integrity of the seed genomic DNA was not affected after drying seeds in the two methods. However, drying in silica gel to 4.5% moisture content and drying under laboratory conditions to 5.4% moisture content resulted in the loss of seed RNA integrity.

A field experiment informs expected patterns of conifer regeneration after disturbance under changing climate conditions

2015 ◽  
Vol 45 (11) ◽  
pp. 1607-1616 ◽  
Author(s):  
Monica T. Rother ◽  
Thomas T. Veblen ◽  
Luke G. Furman
Keyword(s):  
Field Experiment ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Douglas Fir ◽  
Tree Regeneration ◽  
Colorado Front Range ◽  
Front Range ◽  
Average Growth ◽  
Growth And Survival ◽  
Treatment Type

Climate change may inhibit tree regeneration following disturbances such as wildfire, altering post-disturbance vegetation trajectories. We implemented a field experiment to examine the effects of manipulations of temperature and water on ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings planted in a low-elevation, recently disturbed setting of the Colorado Front Range. We implemented four treatments: warmed only (Wm), watered only (Wt), warmed and watered (WmWt), and control (Co). We found that measures of growth and survival varied significantly by treatment type. Average growth and survival was highest in the Wt plots, followed by the Co, WmWt, and Wm plots, respectively. This general trend was observed for both conifer species, although average growth and survival was generally higher in ponderosa pine than in Douglas-fir. Our findings suggest that warming temperatures and associated drought are likely to inhibit post-disturbance regeneration of ponderosa pine and Douglas-fir in low-elevation forests of the Colorado Front Range and that future vegetation composition and structure may differ notably from historic patterns in some areas. Our findings are relevant to other forested ecosystems in which a warming climate may similarly inhibit regeneration by dominant tree species.

scholarly journals Soluble carbohydrates in cereal (wheat, rye, triticale) seed after storage under accelerated ageing conditions

2011 ◽  
Vol 79 (1) ◽  
pp. 21-25
Author(s):  
Agnieszka I. Piotrowicz-Cieślak ◽  
Maciej Niedzielski ◽  
Dariusz J. Michalczyk ◽  
Wiesław Łuczak ◽  
Barbara Adomas
Keyword(s):  
Moisture Content ◽  
Spring Wheat ◽  
Soluble Sugars ◽  
Dry Mass ◽  
Soluble Carbohydrates ◽  
Accelerated Ageing ◽  
Winter Rye ◽  
Seed Moisture Content ◽  
Winter Triticale ◽  
Seed Moisture

Germinability and the content of soluble carbohydrates were analysed in cereal seed (winter rye, cv. Warko; spring wheat, cv. Santa; hexaploid winter triticale, cv. Fidelio and cv. Woltario). Seed moisture content (mc) was equilibrated over silica gel to 0.08 g H<sub>2</sub>O/g dry mass and stored in a desiccator at 20<sup>o</sup>C for up to 205 weeks or were equilibrated to mc 0.06, 0.08 or 0.10 g H<sub>2</sub>O/g dm and subjected to artificial aging at 35<sup>o</sup>C in air-tight laminated aluminium foil packages for 205 weeks. It was shown that the rate of seed aging depended on the species and seed moisture content. The fastest decrease of germinability upon storage was observed in seed with the highest moisture level. Complete germinability loss for winter rye, winter triticale cv. Fidelio, winter triticale cv. Woltario and spring wheat seed with mc 0.10 g H<sub>2</sub>O/g dm<sup>3</sup> occurred after 81, 81, 101 and 133 weeks, respectively. Fructose, glucose, galactose, myo-inositol, sucrose, galactinol, raffinose, stachyose and verbascose were the main soluble carbohydrates found in the seed. The obtained data on the contents of specific sugars and the composition of soluble sugars fraction in seed of rye, wheat and triticale did not corroborate any profound effect of reducing sugars, sucrose and oligosaccharides on seed longevity.

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