Chemical composition of forest fuels affecting their thermal behavior

1986 ◽  
Vol 16 (4) ◽  
pp. 721-726 ◽  
Author(s):  
Janice M. Rogers ◽  
Ronald A. Susott ◽  
Rick G. Kelsey
Keyword(s):  
Chemical Composition ◽  
Thermal Behavior ◽  
Ponderosa Pine ◽  
Fire Behavior ◽  
Chemical Components ◽  
Plant Materials ◽  
Thermal Reactions ◽  
Forest Fuels ◽  
Before And After ◽  
Flaming Combustion

Flaming combustion is dependent upon the production of flammable volatiles that originate from the heating of the fuel materials. The thermal reactions that take place during this heating are determined by the chemical composition of the fuel. A knowledge of fuel chemistry and thermal reactivity can be useful in understanding and predicting fire behavior. Four plant materials were studied because their thermal decomposition curves showed unusually strong peaks from unknown combustible volatiles. The objective was to isolate and identify the chemical source of these volatiles. The tissues were methodically fractionated by following previously published techniques. Effects of each fractionation were carefully monitored by thermogravimetric analysis before and after treatment. Arabinogalactan was identified as the source of 325–350 °C volatiles from western larch (Larixoccidentalis Nutt.) wood. The major component of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) bark that decomposed above 400 °C was suberin. Foliage from gallberry (Ilexglabra (L.) Gray) and ponderosa pine (Pinusponderosa Laws.) contained cutin, which was responsible for their volatiles produced above 400 °C. The thermal behaviors of suberin and cutin reflect their similar chemical composition. The presence of these chemical components may produce similar thermal behavior in numerous other plant tissues.

scholarly journals Limited Effects of Long-Term Repeated Season and Interval of Prescribed Burning on Understory Vegetation Compositional Trajectories and Indicator Species in Ponderosa Pine Forests of Northeastern Oregon, USA

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 834
Author(s):  
Harold S. J. Zald ◽  
Becky K. Kerns ◽  
Michelle A. Day
Keyword(s):  
Indicator Species ◽  
Ponderosa Pine ◽  
Prescribed Burning ◽  
Vascular Plant ◽  
Fire Behavior ◽  
Understory Vegetation ◽  
Forest Composition ◽  
Forest Fuels ◽  
Ponderosa Pine Forests ◽  
Over Time

Fire exclusion has dramatically altered historically fire adapted forests across western North America. In response, forest managers reduce forest fuels with mechanical thinning and/or prescribed burning to alter fire behavior, with additional objectives of restoring forest composition, structure, and ecosystem processes. There has been extensive research on the effects of fuel reduction and restoration treatments on trees, fuels, regeneration, and fire behavior; but less is known about how these treatments influence understory vegetation, which contains the majority of vascular plant diversity in many dry conifer forests. Of particular interest is how understory vegetation may respond to the season and interval of prescribed burning. The season and interval of prescribed burning is often determined by operational constraints rather than historical fire regimes, potentially resulting in fire conditions and burn intervals to which native plants are poorly adapted. In this study, we examined how understory vegetation has responded to season and interval of prescribed burning in ponderosa pine (Pinus ponderosa) forests in the Blue Mountains of northeastern Oregon, USA. Using over a decade (2002–2015) of understory vegetation data collected in stands with different intervals (5 versus 15 year) and seasons (spring versus fall) of prescribed burning, we quantified how season and interval of prescribed burning has influenced understory vegetation compositional trajectories and indicator species over time. Season of prescribed burning resulted in different understory communities and distinct trajectories of understory composition over time, but interval of burning did not. Indicator species analysis suggests fall burning is facilitating early seral species, with native annual forbs displaying ephemeral responses to frequent burning, while invasive cheatgrass (Bromus tectorum) increased in abundance and frequency across all treatments over time. These findings indicate that understory vegetation in these ecosystems are sensitive to seasonality of burning, but the responses are subtle. Our findings suggest season and interval of prescribed burning used in this study do not result in large changes in understory vegetation community composition, a key consideration as land managers increase the pace and scale of prescribed fire in these forests.

Dwarf mistletoe effects on fuel loadings in ponderosa pine forests in northern Arizona

2007 ◽  
Vol 37 (3) ◽  
pp. 662-670 ◽  
Author(s):  
Chad Hoffman ◽  
Robert Mathiasen ◽  
Carolyn Hull Sieg
Keyword(s):  
Ponderosa Pine ◽  
Fire Behavior ◽  
Fuel Loading ◽  
Dwarf Mistletoe ◽  
Forest Fuels ◽  
Ponderosa Pine Forests ◽  
Northern Arizona ◽  
Basaltic Soils ◽  
Four Levels ◽  
Fuels Treatments

Southwestern dwarf mistletoe ( Arceuthobium vaginatum (Willd.) J. Presl ssp. cryptopodum ) infests about 0.9 million ha in the southwestern United States. Several studies suggest that dwarf mistletoes affect forest fuels and fire behavior; however, few studies have quantified these effects. We compared surface fuel loadings and predicted fire behavior among four levels of dwarf mistletoe infestation (none, light, moderate, and severe) in a total of 239 plots on 11 sites on basaltic soils in northern Arizona. In each plot we measured tree attributes, dwarf mistletoe rating and surface fuel loading. Stands severely infested by dwarf mistletoe had lower (P < 0.05) tree density and higher snag density, but higher (P < 0.05) total surface fuel loadings and total fuel loadings >7.62 cm and <7.62 cm, than non-infested stands. However, there were no statistical differences in any canopy fuel variables among infestation classes. Predicted fire behavior indicated that the wind speed required to promote the spread of a surface fire into the canopy was lower in severely infested stands than in non-infested stands. These results suggest that stands in northern Arizona that are severely infested with dwarf mistletoe should be priority areas for fuels treatments.

scholarly journals Mastication and Prescribed Fire Influences on Tree Mortality and Predicted Fire Behavior in Ponderosa Pine

2012 ◽  
Vol 27 (1) ◽  
pp. 36-41 ◽  
Author(s):  
Alicia L. Reiner ◽  
Nicole M. Vaillant ◽  
Scott N. Dailey
Keyword(s):  
Pinus Ponderosa ◽  
Prescribed Fire ◽  
Ponderosa Pine ◽  
Tree Mortality ◽  
Block Design ◽  
Fire Behavior ◽  
Mortality Data ◽  
Before And After ◽  
Random Block Design ◽  
Four Blocks

Abstract The purpose of this study was to provide land managers with information on potential wildfire behavior and tree mortality associated with mastication and masticated/fire treatments in a plantation. Additionally, the effect of pulling fuels away from tree boles before applying fire treatment was studied in relation to tree mortality. Fuel characteristics and tree mortality data were gathered before and after treatments in a 25-year-old ponderosa pine (Pinus ponderosa C. Lawson) plantation. A random block design was used with three treatments plus a control at each of four blocks. Four plots were established as subsamples within each of the treatment and control sections of each block. Potential wildfire behavior for posttreatment fuel conditions was modeled for 90th and 97th percentile fire weather. Predicted rates of spread and flame lengths were higher for fuel conditions resulting from the mastication treatments than for the masticated/fire treatments or the controls. Torching and crowning indices indicated that higher windspeeds would be necessary to promote torching for areas treated with mastication/fire than for mastication or the controls. Tree mortality was 32 and 17% the first year after burning in masticated/fire and masticated/pull-back/fire plots, respectively, and 49 and 27% the second year. Our potential wildfire behavior results indicate that the risk of crown fire can be somewhat reduced by mastication and further reduced if mastication is followed up with prescribed fire to consume surface fuels. However, moderate levels of tree mortality seem inevitable when burning masticated fuels in a plantation and may only marginally be reduced by pulling fuels away from tree boles, which increases treatment costs.

scholarly journals Hardness of Densified Wood in Relation to Changed Chemical Composition

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 506 ◽  
Author(s):  
Przemysław Mania ◽  
Miłosz Wróblewski ◽  
Adam Wójciak ◽  
Edward Roszyk ◽  
Waldemar Moliński
Keyword(s):  
Chemical Composition ◽  
Cell Walls ◽  
Lignin Content ◽  
Densified Wood ◽  
Chemical Components ◽  
Poplar Wood ◽  
Birch Wood ◽  
Partial Reduction ◽  
Structural Components ◽  
Before And After

The aim of this study was to evaluate some of the properties of densified poplar and birch wood earlier subjected to partial delignification of cell walls. The effects of delignification are presented as a comparison of the content of basic structural components in wood before and after chemical modification. In birch wood, the lignin content decreased by 20%, while that of cellulose decreased by 9.7% and that of hemicellulose decreased by 64.9%. In poplar, the lignin content decreased by 34.1%, that of cellulose decreaed by 13.5%, and that of hemicellulose decreased by 58.0%. The hardness of densified birch and poplar wood, after partial reduction of chemical components, was 147 and 111 MPa, respectively, and, compared with natural (non-densified) wood, was almost 4.5 times and 7 times higher, respectively. Poplar wood was more densified (without delignification 238% and after delignification 281%). In the case of birch wood, the density levels were 176% and 188%, respectively.

REPEATED LONG-TERM SPACE FLIGHTS: PROTEOMIC INVESTIGATIONS OF COSMONAUTS' BLOOD

2020 ◽  
Vol 54 (5) ◽  
pp. 15-22
Author(s):  
I.M. Larina ◽  
◽  
D.N. Kashirina ◽  
K.S. Kireev ◽  
A.I. Grigoriev ◽  
...  
Keyword(s):  
Bone Structure ◽  
Space Station ◽  
The Body ◽  
Coagulation Cascade ◽  
Chemical Components ◽  
Blood Proteins ◽  
Blood Indices ◽  
Before And After ◽  
Biochemical Indices

We performed the first ever comparative analysis of modifications in the proteome, ionogram and some other blood plasma biochemical indices of 18 male cosmonauts (44 ± 6 years of age) before and after maiden or repeated long-term missions to the Russian segment of the International space station (ISS RS). Levels of proteins, substrates and ions as well as chemical components were measured using the LC-MS-based proteomics and routine biochemical techniques. A total of 256 to 281 indices were investigated with the methods of descriptive statistic, regression analysis, and access to bioinformatics resources. It was shown that blood indices recovery from the maiden and repeated missions reflects changes in the body systems and goes at a various speed. The results of measurements made prior to launch and on day 7 after landing are dependent on the number of missions. The bioinformatics techniques showed that after maiden missions both the mediator proteins of alkaline phosphatase (AP) and blood proteins with reliably changing concentrations are associated with the bio-processes including stress, metabolism and DNA reparation, apoptosis, catabolism and proteolysis. During early re-adaptation from repeated missions the AP level was affected by bone remodeling, phosphorylation, angiogenesis and coagulation cascade suggesting a distinct and urgent trigger of the processes of bone structure and mineralization.

scholarly journals The chemical composition of Lessonia berteroana (ex L. nigrescens) in kelp harvest management and open access areas near Coquimbo, Chile

2018 ◽  
Vol 46 (2) ◽  
pp. 258-267
Author(s):  
J.M. Alonso Vega ◽  
Pedro H. Toledo
Keyword(s):  
Resource Management ◽  
Chemical Composition ◽  
Open Access ◽  
Environmental Changes ◽  
Chemical Components ◽  
Optimal Harvesting ◽  
Harvest Management ◽  
Species Population ◽  
Pressure Indicators ◽  
Lessonia Berteroana

Lessonia berteroana (ex L. nigrescens) is kelp freely harvested from Open Access Areas (OAA), and to some extent controlled, from Management and Exploitation Areas for Benthic Resources (MEABR). Harvesting pressures can change population dynamics, mainly in OAAs. In particular, harvesting may alter the chemical components of plants. Therefore, the aim of this study was to determine the harvesting effects on the chemical composition of L. berteroana from MEABR and OAA sampled during different seasons (spring and fall) and at two sites (Talquilla and Lagunillas) near Coquimbo (30°S), Chile. The crude protein (13.5 ± 1.0%), total lipids (0.9 ± 0.2%), crude fiber (16.3 ± 1.6%), ash (30.1 ± 1.5%), and nitrogen-free extract (39.2 ± 2.0%) contents of L. berteroana were within reference values for Laminariales species. Population descriptors and chemical analyses showed that harvesting had local effects, rather than being affected by a resource management strategy (OAA vs MEABR). The seasonal anticipator nature of L. berteroana may explain the detected seasonality of it's chemical composition. Regarding functional morphological structures, chemical composition in the fronds was more variable than in the stipes and perennial holdfast, probably since leaves are ephemeral structures susceptible to environmental changes and that play a functional, rather than structural, role in kelp. In the context of Chilean kelp resource management, monitoring chemical composition is useful for determining optimal harvesting periods to local scale and for deciding when commercially valuable compounds, such as alginate, should be extracted. These data also complement harvesting pressure indicators based on L. berteroana demographic parameters.

scholarly journals Effects of rhizosphere fungi on the chemical composition of fruits of the medicinal plant Cinnamomum migao endemic to southwestern China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jingzhong Chen ◽  
Xiaolong Huang ◽  
Bingli Tong ◽  
Deng Wang ◽  
Jiming Liu ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Fungal Community ◽  
Small Population ◽  
Biologically Active ◽  
Fungal Communities ◽  
Chemical Components ◽  
Rhizosphere Fungi ◽  
Medicinal Value ◽  
Main Driver ◽  
Fungal Populations

Abstract Background This study examined how rhizosphere fungi influence the accumulation of chemical components in fruits of a small population species of Cinnamomum migao. Results Ascomycota and Basidiomycota were dominant in the rhizosphere fungal community of C. migao. Pestalotiopsis and Gibellulopsis were associated with α-Terpineol and sabinene content, and Gibellulopsis was associated with crude fat and carbohydrate content. There were significant differences in rhizosphere fungal populations between watersheds, and there was no obvious change between fruiting periods. Gibberella, Ilyonectria, Micropsalliota, and Geminibasidium promoted sabinene accumulation, and Clitocybula promoted α-Terpineol accumulation. Conclusion The climate-related differentiation of rhizosphere fungal communities in watershed areas is the main driver of the chemical composition of C. migao fruit. The control of the production of biologically active compounds by the rhizosphere fungal community provides new opportunities to increase the industrial and medicinal value of the fruit of C. migao.

Comparative Study on Compositions of Oil-Water Transition Layer before and after ClO2-Treatment Process

2013 ◽  
Vol 652-654 ◽  
pp. 749-752
Author(s):  
Dan Dan Yuan ◽  
Hong Jun Wu ◽  
Hai Xia Sheng ◽  
Xin Sui ◽  
Bao Hui Wang
Keyword(s):  
Chemical Composition ◽  
Transition Layer ◽  
Solid Phase ◽  
Settling Tank ◽  
Physical Structure ◽  
Solid Particles ◽  
Viscosity Reduction ◽  
Insoluble Residue ◽  
Before And After ◽  
Oil Water

In order to meet the need of separating oil from water in the settling tank of the oilfield, ClO2 treatment for oil-water transition layer in settling tank is introduced. The field test displayed that the technique was achieved by a good performance. For understanding the oxidation and mechanism, compositions of oil-water transition layer were comparatively studied for before/after ClO2-treatment in this paper.The experimental results show that the compositions before and after ClO2-treatment, including physical structure and chemical composition, were varied in the great extension. The physical structure, consisting of water, oil and solid phase, was reduced to less than 5% of water and 0.5% of solid particle and increased to 95% of oil in layer compared with before-treatment, easily leading to clearly separating water from oil. The chemical composition of iron sulfide and acid insoluble substance in solid phase was decreased to more than 90% while the carbonate was reduced more than 70% . After the treatment, the viscosity reduction of the water phase in the layer was reached to 50% after oxidation demulsification with ClO2. The chemistry was discussed based on the principles and experiments. Due to ClO2 destroying (oxidizing) the rigid interface membrane structure which is supported by natural surfactant, polymer and solid particles with interface-active materials, the action accelerates the separating of water and oil and sedimentation of insoluble residue of acid in the layer. By demonstrating the experimental data and discussion, we can effectively control the oxidation performance of chlorine dioxide, which is very meaningful for oilfield on the aspect of stable production of petroleum.

Sign in / Sign up

Export Citation Format

Share Document