Effects of fuel characteristics on ember generation characteristics at branch-scales

2019 ◽  
Vol 28 (12) ◽  
pp. 941 ◽  
Author(s):  
Tyler R. Hudson ◽  
David L. Blunck
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Small Diameter ◽  
Quercus Alba ◽  
White Oak ◽  
Western Juniper ◽  
Crossflow Velocity ◽  
Fuel Characteristics ◽  
Time Required ◽  
Significant Factors

Spot fires caused by lofted embers (i.e. firebrands) can be a significant factor in the spread of wildfires. Embers can be especially dangerous near the wildland–urban interface (WUI) because of the potential for the fire to be spread near or on structures. This work sought to identify how ember generation changes for different fuel characteristics and environmental conditions. Samples were burned in a heated wind tunnel and the time required for the ember(s) to form was measured using a DSLR camera. A factorial analysis of variance was used to determine the sensitivity of the time to generation to species, diameter, moisture content, fuel condition (i.e. dowel v. natural sample), crossflow temperature and crossflow velocity. Four fuel species were evaluated: Douglas fir (Pseudotsuga menziesii), western juniper (Juniperus occidentalis), ponderosa pine (Pinus ponderosa) and white oak (Quercus alba). The diameter of the samples had the greatest effect on the time to generation and the fuel species had the second greatest effect. The small diameter samples were relatively insensitive to changes in other parameters. Natural samples required significantly longer time than dowels to generate an ember. These conclusions suggest that fuel morphology is one of the most significant factors influencing ember generation.

Effects of fuel morphology on ember generation characteristics at the tree scale

2020 ◽  
Vol 29 (11) ◽  
pp. 1042
Author(s):  
Tyler R. Hudson ◽  
Ryan B. Bray ◽  
David L. Blunck ◽  
Wesley Page ◽  
Bret Butler
Keyword(s):  
Mass Loss ◽  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Douglas Fir ◽  
Biological Factors ◽  
Abies Grandis ◽  
Western Juniper ◽  
Juniperus Occidentalis ◽  
Spot Fires

This work reports characteristics of embers generated by torching trees and seeks to identify the important physical and biological factors involved. The size of embers, number flux and propensity to ignite spot fires (i.e. number flux of ‘hot’ embers) are reported for several tree species under different combinations of number (one, three or five) and moisture content (11–193%). Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis), western juniper (Juniperus occidentalis) and ponderosa pine (Pinus ponderosa) trees were evaluated. Embers were collected on an array of fire-resistant fabric panels and trays filled with water. Douglas-fir trees generated the highest average ember flux per kilogram of mass loss during torching, whereas grand fir trees generated the highest ‘hot’ ember flux per kilogram of mass loss. Western juniper produced the largest fraction of ‘hot’ embers, with ~30% of the embers generated being hot enough to leave char marks. In contrast, only 6% of the embers generated by ponderosa pine were hot enough to leave char marks. Results from this study can be used to help understand the propensity of different species of tree to produce embers and the portion of embers that may be hot enough to start a spot fire.

"Black Bark" Ponderosa Pine: Tree Grade Definition and Value Comparison with Old-Growth Trees

1994 ◽  
Vol 9 (1) ◽  
pp. 8-13 ◽  
Author(s):  
Susan Willits
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Control Sample ◽  
Small Diameter ◽  
Old Growth ◽  
Pine Tree ◽  
Common Grade ◽  
Small Diameter Trees ◽  
Crown Characteristics ◽  
Eastern Washington

Abstract A ponderosa pine (Pinus ponderosa) tree grade has been developed to separate lower value, small-diameter trees typical of young-growth stands from small-diameter old-growth trees. The tree grade uses a combination of bark, limb, and crown characteristics to identify the "black bark," trees. The tree grade was tested in two shop type mills and one dimension mill in southern Oregon and eastern Washington. Significant differences in value were found between the sample of black bark pine and the grade 5 control sample. Differences in value increased with diameter because of increased opportunities to recover high-quality lumber from the larger old-growth trees. The dimension mill recovered more lumber volume from the smaller diameter logs because of fewer sawlines and smaller rough-green sizes. Even though the shop mills recovered lower volumes, they did recover higher value by producing Shop and Common grade lumber rather than standard Dimension grades. Overall the differences compensated for each other, and both mill types recovered roughly equal value from logs of similar grade and size. West. J. Appl. For. 9(1): 8-13.

Western juniper and ponderosa pine ecotonal climate–growth relationships across landscape gradients in southern Oregon

2008 ◽  
Vol 38 (12) ◽  
pp. 3021-3032 ◽  
Author(s):  
Kevin C. Knutson ◽  
David A. Pyke
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Radial Growth ◽  
Winter Precipitation ◽  
Forest Growth ◽  
Annual Growth ◽  
Growth Responses ◽  
Climate Fluctuations ◽  
Western Juniper ◽  
Tree Ring Data

Forecasts of climate change for the Pacific northwestern United States predict warmer temperatures, increased winter precipitation, and drier summers. Prediction of forest growth responses to these climate fluctuations requires identification of climatic variables limiting tree growth, particularly at limits of tree species distributions. We addressed this problem at the pine–woodland ecotone using tree-ring data for western juniper ( Juniperus occidentalis var. occidentalis Hook.) and ponderosa pine ( Pinus ponderosa Dougl. ex Loud.) from southern Oregon. Annual growth chronologies for 1950–2000 were developed for each species at 17 locations. Correlation and linear regression of climate–growth relationships revealed that radial growth in both species is highly dependent on October–June precipitation events that recharge growing season soil water. Mean annual radial growth for the nine driest years suggests that annual growth in both species is more sensitive to drought at lower elevations and sites with steeper slopes and sandy or rocky soils. Future increases in winter precipitation could increase productivity in both species at the pine–woodland ecotone. Growth responses, however, will also likely vary across landscape features, and our findings suggest that heightened sensitivity to future drought periods and increased temperatures in the two species will predominantly occur at lower elevation sites with poor water-holding capacities.

Manufacture of laminated strand veneer (LSV) composite. Part 1: Optimization and characterization of thin strand veneers

Holzforschung ◽  
2008 ◽  
Vol 62 (6) ◽  
Author(s):  
Shilo W. Weight ◽  
Vikram Yadama
Keyword(s):  
Aspect Ratio ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Phenol Formaldehyde ◽  
Small Diameter ◽  
Parent Material ◽  
Modulus Of Rupture ◽  
Formaldehyde Resin ◽  
Old Growth Forest ◽  
Platen Temperature

Abstract The forest resources are changing due to fire prevention and depletion of old growth forest. Applications for small-diameter juvenile timber, especially for low-value species, such as ponderosa pine (Pinus ponderosa) are needed. In this study, a novel thin wood strand composite of P. ponderosa, 3.2 mm thick, is introduced as a veneer substitute. Optimization was performed for the processing parameters phenol formaldehyde resin content, platen temperature, and the aspect ratio strand length to thickness (L/t). Mean modulus of elasticity and modulus of rupture values of 10.2 GPa and 79.1 MPa, respectively, were obtained with the optimized formulation (5.5% resin, platen temperature 152°C, and aspect ratio of 430). These values were approximately 2–2.5 times higher than the parent small-diameter ponderosa pine lumber. The results indicate that fast-growing low-density species – such as hybrid poplars, or small-diameter timber with predominantly juvenile wood – could potentially be used to manufacture strand veneers of consistent quality with significantly higher strength and stiffness than parent material.

scholarly journals Processing Value of Small-Diameter Sawtimber at Conventional Stud Sawmills and Modern High-Speed, Small-Log Sawmills in the Western United States—A Comparison

2000 ◽  
Vol 15 (4) ◽  
pp. 208-212 ◽  
Author(s):  
Francis G. Wagner ◽  
Carl E. Fiedler ◽  
Charles E. Keegan
Keyword(s):  
United States ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
High Speed ◽  
Fire Suppression ◽  
Small Diameter ◽  
Selective Logging ◽  
Western United States ◽  
Forest Composition ◽  
Delivery Costs

Abstract Past selective logging of early successional species [e.g., ponderosa pine (Pinus ponderosa)] and effective fire suppression have dramatically altered forest composition and health over millions of acres in the western United States. Implementation of ecological restoration treatments to address these conditions will produce large volumes of small-diameter sawtimber for processing. Since sawmills currently process a majority of sawtimber harvested in the West (more than 80% in some regions), this study concentrated on determining the value of small-diameter sawtimber delivered to sawmills. A conventional stud sawmill and a modern, high-speed, small-log sawmill were profiled. A simulator (MSUSP) was employed to describe these sawmills and to determine breakeven delivered-sawtimber values by dbh class for each sawmill. Data inputs included machinery type, mill layout, machine speeds, volume and grade recovery, product prices, and fixed and variable manufacturing costs. Results showed that sawtimber 9 in. dbh and under could not cover harvest and delivery costs and earn even a modest (10%) return on invested (ROI) capital at the conventional stud sawmill and that sawtimber 7.5 in. dbh and smaller had negative values. However with a 10% ROI capital, the value of all sizes of sawtimber at the modern, high-speed sawmill equaled or exceeded harvest and delivery costs. West. J. Appl. For. 15(4):208–212.

Fine-scale variation of historical fire regimes in sagebrush-steppe and juniper woodland: an example from California, USA

2008 ◽  
Vol 17 (2) ◽  
pp. 245 ◽  
Author(s):  
Richard F. Miller ◽  
Emily K. Heyerdahl
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Soil Depth ◽  
Spatial Scales ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Big Sagebrush ◽  
Western Juniper ◽  
Fine Fuels ◽  
Fire Intervals

Coarse-scale estimates of fire intervals across the mountain big sagebrush (Artemisia tridentata spp. vaseyana (Rydb.) Beetle) alliance range from decades to centuries. However, soil depth and texture can affect the abundance and continuity of fine fuels and vary at fine spatial scales, suggesting fire regimes may vary at similar scales. We explored variation in fire frequency across 4000 ha in four plant associations with differing soils in which mountain big sagebrush and western juniper (Juniperus occidentalis subsp. occidentalis Hook.) were diagnostic or a transitory component. We reconstructed fire frequency from fire-scarred ponderosa pine (Pinus ponderosa P. & C. Lawson) in one association. The other three associations lacked fire-scarred trees so we inferred fire frequency from establishment or death dates of western juniper and a model of the rate of post-fire succession we developed from current vegetation along a chronosequence of time-since-fire. Historical fire frequency varied at fine spatial scales in response to soil-driven variation in fuel abundance and continuity and spanned the range of frequencies currently debated. Fire intervals ranged from decades in areas of deep, productive soils where fine fuels were likely abundant and continuous, to centuries in areas of shallow, coarse soils where fine fuel was likely limited.

scholarly journals Evaluation of Physical Barriers to Protect Ponderosa Pine Seedlings from Pocket Gophers

1999 ◽  
Vol 14 (3) ◽  
pp. 164-168 ◽  
Author(s):  
Michael J. Pipas ◽  
Gary W. Witmer
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Seedling Mortality ◽  
Pocket Gophers ◽  
Thomomys Talpoides ◽  
Pine Seedlings ◽  
Physical Barriers ◽  
Growth Of Seedlings ◽  
Medium Weight ◽  
Better Than

Abstract A 2 yr study on the Rogue River and Mt. Hood National Forests in Oregon evaluated physical barriers for protection of Pinus ponderosa seedlings against damage by Thomomys talpoides. Seedlings protected with one of three weights of: (1) plastic mesh tubing (Vexar®) or (2) sandpapertubing (Durite®) were evaluated against control seedlings. On the Rogue River sites, Vexar® seedlings had the highest survival (62.6%), followed by the controls (59.1%), then Durite® seedlings (17.9%). Gophers were the primary cause of death for the Vexar® seedlings, versus desiccation for the Durite® seedlings. On the Mt. Hood sites, heavyweight Vexar® seedlings had the highest survival (35.4%), medium-weight Durite® seedlings the lowest (2.7%). Seedling mortality caused by gophers was highest for controls (70.2%), followed by light-weight (62.2%) and heavy-weight (53.9%) Vexar® treatments. Overall survival was low (Rogue River = 42%, Mt. Hood = 19.8%). Growth was greatest for the control seedlings but only significantly greater than growth of Durite® seedlings on the Rogue River sites. Growth of seedlings was not compromised by the Vexar® tubing. Although neither type of tubing was highly protective, Vexar® tubes performed better than Durite® tubes. West. J. Appl. For. 14(3):164-168.

scholarly journals Impacts of increasing fine fuel loads on acorn germination and early growth of oak seedlings

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Rachel E. Nation ◽  
Heather D. Alexander ◽  
Geoff Denny ◽  
Jennifer K. McDaniel ◽  
Alison K. Paulson
Keyword(s):  
Prescribed Fire ◽  
Germination Rate ◽  
Growth Patterns ◽  
Leaf Number ◽  
Fuel Load ◽  
Quercus Alba ◽  
White Oak ◽  
Fuel Treatment ◽  
Basal Diameter ◽  
Fuel Loads

Abstract Background Prescribed fire is increasingly used to restore and maintain upland oak (Quercus L. spp.) ecosystems in the central and eastern US. However, little is known about how prescribed fire affects recently fallen acorns under different fine fuel loads, which can vary with stand composition and basal area, burn season, and fire frequency. We conducted plot-level (1 m2) burns in an upland oak stand in northern Mississippi, USA, during December 2018, using single (i.e., ambient), double, and triple fine fuel loads, representative of those in nearby unburned and recently fire-treated, closed-canopy stands. Pre burn, we placed 30 acorns each of white oak (Quercus alba L.) and Shumard oak (Quercus shumardii Buckley) ~1 cm below the litter surface in five plots of each fuel treatment. Immediately post burn, we planted unburned and burned acorns in a greenhouse. After ~50% of each species’ unburned acorns germinated, we measured percent germination and height, basal diameter, and leaf number of germinating seedlings weekly for 11 weeks. Then, we harvested seedlings to determine above- and belowground biomass. Results The single fuel treatment reduced acorn germination rates of both species to ~40% compared to ~88% in unburned acorns. When burned in double and triple fuel loads, acorns of both species had a <5% germination rate. There was no difference in basal diameter, leaf number, or biomass of seedlings from burned versus unburned acorns for either species. However, seedlings originating from burned acorns of both species were ~11% shorter than those from unburned acorns. Thus, both species responded similarly to fuel load treatments. Conclusions Acorns of both species exhibited greater survival with lower fine fuel loads, and consequently lower percent fuel consumption. Acorns germinating post fire generally produced seedlings with growth patterns similar to seedlings originating from unburned acorns. These findings indicate that regular, repeated prescribed fires or canopy reductions that limit fine fuel accumulation and create heterogeneous fuel beds are likely to increase acorn germination rates relative to unburned sites or those with recently introduced fire.

scholarly journals Germination, Establishment, and Mortality of Naturally Seeded Southwestern Ponderosa Pine

2003 ◽  
Vol 18 (2) ◽  
pp. 109-114 ◽  
Author(s):  
Steven J. Stein ◽  
Diana N. Kimberling
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Mineral Soil ◽  
Mortality Data ◽  
Mortality Factors ◽  
Seedling Mortality ◽  
Prescribed Burns ◽  
Factors Affecting ◽  
Northern Arizona ◽  
Lepidopteran Larvae

Abstract Information on the mortality factors affecting naturally seeded conifer seedlings is becoming increasingly important to forest managers for both economic and ecological reasons. Mortality factors affecting ponderosa pine (Pinus ponderosa) seedlings immediately following natural germination and through the following year were monitored in Northern Arizona. The four major mortality factors in temporal order included the failure of roots to establish in the soil (27%), herbivory by lepidopteran larvae (28%), desiccation (30%), and winterkill (10%). These mortality factors were compared among seedlings germinating in three different overstory densities and an experimental water treatment. Seedlings that were experimentally watered experienced greater mortality than natural seedlings due to herbivory (40%), nearly as much mortality due to the failure of roots to establish in the soil (20%), less mortality due to winterkill (5%), and no mortality due to desiccation. The seedling mortality data through time were summarized using survivorship curves and life tables. Our results suggest that managers should consider using prescribed burns to decrease the percentage of seedlings that die from failure of their roots to reach mineral soil and from attack by lepidopteran larvae. West. J. Appl. For. 18(2):109–114.

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