Douglas Fir Bark Research Articles

Douglas fir bark: composition, extracts utilization and enzymatic treatment for enrichment of bioactive constituents

Abstract Bark residues from Douglas fir are an abundant resource that is currently used primarily in low-value energy recovery or is landfilled. Bark extractives are rich in diverse compounds like terpenes, fatty acids, phenols, and sugars with potential uses in a variety of high value applications. The study explores the potential of enzymatic hydrolysis to improve phenolic compounds from Douglas fir bark. It also assesses differences in chemical composition among rhytidome, phloem, and comingled bark fractions from an industrial waste pile. Phloem fractions exhibit higher yields of extractives, rhytidome fractions have elevated lignin levels, while the comingled fraction lies between the two except in ash content which was higher than in the separated fractions. Fungal decay tests with Gloeophyllum trabeum and Coniophora puteana on extract treated wood suggest potential for growth inhibition in extracts, about 58–31 % and 30–7% mass loss (in average) respectively, but due to high mass loss at low concentrations an enzymatic modification approach seems crucial for enhanced inhibition. Growth responses in whole-cell fermentation approach display variability depending on the participating microorganisms. Enzymatic hydrolysis with beta-glucosidase improved the antioxidant properties of bark extracts and holds promise for altering the chemical composition and enhancing bioactivity.

KARACİĞER İSKEMİ VE REPERFÜZYON HASARINDA KALP DOKUSUNDA MEYDANA GELEN HASARIN ÖNLENMESİNDE TAKSİFOLİN’İN KORUYUCU ETKİNLİĞİ: DENEYSEL ÇALIŞMA

Aim: Liver ischemia and reperfusion (I/R) is a serious, irreversible health problem in clinical practice. Taxifolin (Tax) is an easy to obtain and use agent found in maritime pine bark, Douglas fir bark and Siberian larch wood. In this study, we examined the protective efficacy of Taxifolin in the correction of cardiac tissue damage that may develop in liver I/R damage. Methods: In our study, a total of 28 Wistar Albino rats, 8-10 weeks old, weighing 250-300 grams, were used. Group 1 (n=7): control group, Group 2 (n=7): Tax group with 50 mg/kg dose orally for 3 weeks, Group 3 (n=7): Liver I/R group for 30 minutes ischemia and 120 minutes of reperfusion were performed. Group 4 (n=7): Tax+Liver I/R group. Results: In our study, MDA analysis was performed to evaluate oxidative stress. In the statistical analysis of MDA values, we observed that there was a statistically significant difference between the serum MDA values of the Tax group and the Tax+Liver I/R group, and the MDA level of the Tax group was lower (p<0.05). In myocyte damage scoring, we observed that the liver I/R group had the highest damage score, while the damage score of the Tax+Liver I/R group was significantly lower than the I/R group (p<0.05). Conclusion: As a result of our study, we observed that there was an increase in serum MDA levels as a result of liver I/R and histopathological changes occurred in the heart tissue. However, Taxifolin has been successful in ameliorating this situation.

A mini-review on engineered biochars as emerging adsorbents in heavy metal removal

Environmental remediation using green adsorbents has been the primary focus of researchers worldwide to promote a sustainable and safe environment. Engineered biochars (E-BCs) from different biomass feedstocks have become highly successful adsorbents to remove heavy metals due to their conducive properties like large surface areas and enhanced functionalities, thereby giving higher removal efficiencies and cyclic stabilities. In this mini-review, an analysis with respect to synthesis, biosorption mechanism, modification methods, and performance comparison with respect to adsorption capacity (AC) of engineering biochars’s are discussed. The coconut shell (AC: 450.50 mg/g), pennisetum sp.straw-a weed species (AC: 763.12 mg/g), Douglas fir bark wood (AC: 127.20 mg/g), corncob (9.62 mg/g) are observed to be the best biosorbent for the heavy metal removal of Pb(II), Cd(II), Cr(VI), and As(V) from aqueous solution. The acid treatment, alkali treatment, salt treatment, oxides treatment, ball milling, steam activation, alumina nanoparticles, magnetic activation, chitosan modification, and nanoscale zero valent iron (nZVI) are the common modification methods to develop E-BC. The future challenges and prospects are also discussed.

Composition and antioxidant properties of extracts from Douglas fir bark

Abstract This study aimed to investigate the antioxidant ability and the chemical composition of apolar and polar extractives from Douglas-fir bark, cork and phloem, establishing a possible correlation with the structural variation along the tree stem and geographic location. Douglas-fir bark extractives’ composition were analyzed at three stem heights in trees from two locations. Cork and phloem extracts’ composition were analyzed in samples collected at stem base. Extractives content in Douglas-fir bark varied between 14 and 31% and polar extractives (11–29%) were dominant over non-polar. Lipophilic extracts were mainly composed of terpenoids, representing 27–77% of all compounds, highlighted by callitrisic acid (11–34%). Sterols were also abundant (6–45%), with β-sitosterol representing 7–33% of all compounds. Alkanoic acids were present in smaller amounts. Ethanol–water extracts showed high phenolic (562–762 mg GAE/g extract), flavonoid and condensed tannins contents (399–683 mg CE/g extract and 120–262 mg CE/g of extract), high scavenging (IC50 2.8 µg extract/mL) and reducing (12 mM Fe2+/g extract) abilities. Cork had high phenolic (819 mg GAE/g extract) and flavonoid contents (524 mg CE/g extract) and high antioxidant capacity (1080 mg TEAC/g extract). Detailed knowledge of Douglas-fir extracts demonstrates their potential as a source of fine chemicals towards different applications.

A Comprehensive Characterization of Pyrolysis Oil from Softwood Barks.

Pyrolysis of raw pine bark, pine, and Douglas-Fir bark was examined. The pyrolysis oil yields of raw pine bark, pine, and Douglas-Fir bark at 500 °C were 29.18%, 26.67%, and 26.65%, respectively. Both energy densification ratios (1.32–1.56) and energy yields (48.40–54.31%) of char are higher than pyrolysis oils (energy densification ratios: 1.13–1.19, energy yields: 30.16–34.42%). The pyrolysis oils have higher heating values (~25 MJ/kg) than bio-oils (~20 MJ/kg) from wood and agricultural residues, and the higher heating values of char (~31 MJ/kg) are comparable to that of many commercial coals. The elemental analysis indicated that the lower O/C value and higher H/C value represent a more valuable source of energy for pyrolysis oils than biomass. The nuclear magnetic resonance results demonstrated that the most abundant hydroxyl groups of pyrolysis oil are aliphatic OH groups, catechol, guaiacol, and p-hydroxy-phenyl OH groups. The aliphatic OH groups are mainly derived from the cleavage of cellulose glycosidic bonds, while the catechol, guaiacol, and p-hydroxy-phenyl OH groups are mostly attributed to the cleavage of the lignin β–O-4 bond. Significant amount of aromatic carbon (~40%) in pyrolysis oils is obtained from tannin and lignin components and the aromatic C–O bonds may be formed by a radical reaction between the aromatic and aliphatic hydroxyl groups. In this study, a comprehensive analytical method was developed to fully understand and evaluate the pyrolysis products produced from softwood barks, which could offer valuable information on the pyrolysis mechanism of biomass and promote better utilization of pyrolysis products.

Age Variation of Douglas-Fir Bark Chemical Composition

The chemical composition of Douglas-fir bark was analyzed at three stem height levels of trees with different ages from two geographical locations. Cork and phloem in the bark’s rhytidome were analyzed separately at stem bottom: extractives (49.8% and 17.0%, respectively), suberin (30.1% in cork) and hemicelluloses, namely arabinose content (25.3% and. 4.8% of all monomers, respectively). Suberin composition includes α,ω-alkanoic diacids (38.6%), ω-hydroxyalkanoic acids (25.6%), alkanoic acids (18.2%), alkanols (2.2%), and aromatics (8.8%). Bark’s chemical composition is age-related, namely regarding suberin content: at 45, 30 and, 17 years of age, bark contained respectively 25.4%, 2.6%, and 0.9% of suberin; 24.5%, 33.9%, and 29.8% of lignin; and 29.4%, 20.6%, and 25.7% of extractives. This difference is due to the small number of periderms and low cork content in barks with 30 or less years. When aiming at a cork-targeted valorization, the lower stem parts of mature Douglas-fir trees should be considered while the high content of polar extractives at all stem heights allows an overall potential valorization.

Inhibition of the Exoglucanase Cel7A by a Douglas-Fir-Condensed Tannin.

Douglas-fir forestry residues are a potential feedstock for saccharification-based biofuels, and condensed tannins are expected to make up ∼3% of the dry mass of this feedstock. Condensed tannins are well-known for their ability to interact with proteins and can bind and inhibit cellulase enzymes used in saccharification. In this study, we use molecular docking and classical molecular dynamics simulations to investigate how a characterized condensed tannin from Douglas-fir bark binds to the exoglucanase Cel7A from Trichoderma reesei. Through looking at the "occupancy" and "residency" of specific amino acid residue-tannin interactions, we find that the binding sites are characterized by many simultaneous tannin-enzyme interactions with the strongest occurring on the catalytic module as opposed to the carbohydrate-binding module. The simulations indicate that tannin inhibition can result from binding at or near the catalytic tunnel's entrance and exit. The analyzed tannin further prefers to bind to loops around the catalytic region and has affinity for aromatic and charged amino acid residues. These insights provide direction for the rational design of tannin-resistant cellulases.

Amelioration of Alcoholic Liver Steatosis by Dihydroquercetin through the Modulation of AMPK-Dependent Lipogenesis Mediated by P2X7R-NLRP3-Inflammasome Activation.

Dihydroquercetin (TAX) is the most abundant dihydroflavone found in onions, milk thistle, and Douglas fir bark. We investigated whether TAX could inhibit lipid accumulation in alcoholic liver steatosis in vivo and in vitro. An in vivo model was established by intragastrically treating mice with ethanol, and an in vitro model was created by treating HepG2 cells with ethanol. TAX regulated SREBP1 and ACC expression by elevating LKB1 and AMPK phosphorylation. Also, TAX upregulated SIRT1 expression, which was suppressed by ethanol intake. Decreased expression of P2X7R and NLRP3 and suppressed cleavage of caspase-1 by TAX resulted in the inhibition of IL-1β production and release. Additionally, TAX reduced lipogenesis and promoted lipid oxidation via the regulation of AMPK and ACC in ethanol-treated steatotic HepG2 cells. TAX downregulated IL-1β cleavage responses to LPS and ATP stimulation in HepG2 cells. P2X7R deficiency attenuated lipid accumulation, characterized by increased AMPK activity and decreased SREBP1 expression in ethanol-treated HepG2 cells. Our data showed that TAX exhibited the ability to inhibit lipogenesis and a hepatoprotective capacity, indicating that TAX has therapeutic potential for preventing alcoholic liver steatosis.

Suitability of Sphagnum Moss, Coir, and Douglas Fir Bark as Soilless Substrates for Container Production of Highbush Blueberry

The purpose of the present study was to investigate the suitability of different soilless substrates for container production of highbush blueberry (Vaccinium sp.). Young plants of ‘Snowchaser’ blueberry were grown in 4.4-L pots filled with media containing 10% perlite and varying proportions of sphagnum moss, coconut (Cocos nucifera L.) coir, and douglas fir [Pseudotsuga menziesii Mirb. (Franco)] bark, as well as a commercially available mix of peatmoss, perlite, and other ingredients for comparison. Total plant dry weight (DW) was similar among the treatments at 72 days after transplanting, but at 128 days, total DW was nearly twice as much in the commercial mix and in media with ≥60% peat or coir than in media with ≥60% bark. Inadequate irrigation likely played a role in poor plant growth in bark. Bark had lower porosity and water holding capacity than peat, coir, or the commercial mix and, therefore, dried quickly between irrigations. Bark also reduced plant uptake efficiency of a number of nutrients, including N, P, K, S, Ca, Mg, Mn, B, Cu, and Zn. Uptake efficiency of P, K, and Mg also differed between plants grown in peat and coir, which in most cases was a function of the initial concentration of nutrients in the media. Before planting, peat had the highest concentration of Mg and Fe among the media, whereas coir had the highest concentration of P and K. Leachate pH was initially lowest with peat and highest with coir but was similar among each of the media treatments by the end of the study. Electrical conductivity (EC) of leachate never exceeded 0.84 dS·m−1 in any treatment. Overall, peat and coir appear to be good substrates for container production of highbush blueberry. Bark, on the other hand, was less suitable, particularly when it exceeded 30% of the total media composition.

Optimizing Douglas-fir bark liquefaction in mixtures of glycerol and polyethylene glycol and KOH

Abstract The outer bark of Douglas-fir (Pseudotsuga menziesii) has a significant amount of cork tissue that may be an important source of chemicals derived from its natural polymers, suberin, cellulose, hemicelluloses and lignin. The present work focuses on the polyalcohol liquefaction of Douglas-fir bark with glycerol and polyethylene glycol (PEG) in order to obtain a liquid that can be further processed to other chemicals and products. The results show that Pseudotsuga bark can be liquefied in a significant percentage in presence of alkali. The best liquefaction yield was obtained with 6% KOH as agents. Although the use of a cosolvent is favorable, good liquefaction yields can also be obtained by glycerol alone. Lower temperatures are favorable as they lead to acceptable liquefaction yields. FTIR-ATR studies showed that all the structural compounds of the bark were attacked and depolymerized. The process tested has a high potential for generation of value-added products from liquefied Douglas-fir bark.

Assessment of hydrothermal pretreatment of various lignocellulosic biomass with CO2 catalyst for enhanced methane and hydrogen production

Hydrothermal pretreatment of five lignocellulosic substrates (i.e. wheat straw, rice straw, biomass sorghum, corn stover and Douglas fir bark) were conducted in the presence of CO2 as a catalyst. To maximize disintegration and conversion into bioenergy (methane and hydrogen), pretreatment temperatures and subsequent pressures varied with a range of 26–175 °C, and 25–102 bars, respectively. Among lignin, cellulose and hemicelluloses, hydrothermal pretreatment caused the highest reduction (23–42%) in hemicelluloses while delignification was limited to only 0–12%. These reductions in structural integrity resulted in 20–30% faster hydrolysis rates during anaerobic digestion for the pretreated substrates of straws, sorghum, and corn stover while Douglas fir bark yielded 172% faster hydrolysis/digestion due to its highly refractory nature in the control. Furans and phenolic compounds formed in the pretreated hydrolyzates were below the inhibitory levels for methane and hydrogen production which had a range of 98–340 ml CH4/g volatile solids (VS) and 5–26 ml H2/g VS, respectively. Results indicated that hydrothermal pretreatment is able to accelerate the rate of biodegradation without generating high levels of inhibitory compounds while showing no discernible effect on ultimate biodegradation.

Cork of Douglas-fir bark: Impact of structural and anatomical features on usage

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is one of the best conifer timber species. Its bark contains a substantial proportion of cork that may have a valorization potential, given adequate structural and cellular features. This study was made here onbark samples from mature trees from the north and central mountains of Portugal. The area proportion of cork was determined by image analysis, the cork tissue was observed with electron scanning microscopy (SEM) and cell dimensions measured.The cork is not continuous within the rhytidome, and the layers are interspersed with phloem regions. The cork layers are not continuous along the tangential or axial directions. Older trees contain on average a thicker rhytidome and a higher proportion of cork. The cork tissue was characterized by the presence of extensive areas of cells that are crushed or completely collapsed, making up a compressed and very compact structure with patches of uncompressed cork. The compression occurs in the radial direction and is clearly observed in transverse and radial sections. In the uncompressed regions the majority of the cork cells are hexagonal and pentagonal prisms stacked base-to-base and aligned in the radial direction in parallel rows. On average, the prism height and base area are 55μm and 1388μm2, respectively, with a 1.3μm cell wall thickness. To obtain pure cork fractions from Douglas-fir bark, trituration and fractionation processes are needed. Also the use of Douglas-fir cork as a cellular material will be restricted by the extensive cell compression.

Removal of cesium ion from contaminated water: Improvement of Douglas fir bark biosorption by a combination of nickel hexacyanoferrate impregnation and TEMPO oxidation

New biosorbents derived from a forestry waste, Douglas fir bark, were developed to remove cesium ion (Cs+) from water. Crude bark was oxidised either by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation or by the Fenton reaction to create carboxyl groups onto the bark’s surface. Subsequently, nickel (II) hexacyanoferrate (III) (NiHCF) was incorporated into crude and oxidised barks. Crude bark has good intrinsic property for Cs+ sorption and TEMPO is the best tested oxidant able to improve this capacity. Structural analyses showed increase as well as important structural modification of bark surface following TEMPO oxidation. A link was established between the observed modifications and the amount of incorporated NiHCF. Combination of TEMPO oxidation and NiHCF impregnation increased Cs+ maximum sorption capacity (qmax) of crude bark by a factor of 7 to reach 1.51mmolg−1. In addition, NiHCF/TEMPO bark could be used within pH range 4–10 with full sorption capacity. Finally, the release of nickel, iron and cyanide during incubation of NiHCF/TEMPO bark with water remained within the legal limits defined by U.S. EPA. Due to its high trapping capacity, pH stability and structural properties, NiHCF/TEMPO bark appears as a promising sorbent for removal of Cs+ from contaminated water.

Modification of biochar surface by air oxidation: Role of pyrolysis temperature

This paper reports the effects of pyrolysis temperature on biochar to oxidation by air. Eighteen biochars were produced from the pyrolysis of Douglas fir wood (DFW), Douglas fir bark (DFB), and hybrid poplar wood (HP) at six temperatures (623, 673, 723, 773, 823 and 873 K) in a lab scale spoon reactor. The oxidation step for all biochars produced was conducted at 523 K in the presence of air in a spoon reactor. The elemental and proximate analyses of all the oxidized and un-oxidized chars suggest that the carbonaceous materials produced at low temperature are more susceptible to oxidation than those produced at high temperature. A number of surface properties of resultant biochars were examined to better understand how pyrolysis temperatures and feedstock sources relate to the development of surface characteristics. The removal of volatiles during the pyrolysis step resulted in the gradual creation of microporosity detectable by CO2 adsorption but which was difficult to detect with N2 adsorption, suggesting that the chars contain micropores mostly less than 1 nm in entrance dimension. In some cases, the surface area decreased after being oxidized likely due to the blockage of micropores by oxygen-containing functional groups. The surface composition determined by XPS and Boehm titration confirms that greater quantities of carbonyl and carboxyl groups are formed on biochars produced at low temperature. The formation of these oxygenated functional groups contributes to add negative charges on the surface and consequently the pH at the point of zero charge increases for un-oxidized biochars.

Influence of feedstock source and pyrolysis temperature on biochar bulk and surface properties

Eighteen biochar samples were produced from the pyrolysis of Douglas fir wood (DFW), Douglas fir bark (DFB), and hybrid poplar wood (HP) at six temperatures (623, 673, 723, 773, 823 and 873 K) in a lab scale spoon reactor. Changes in the bulk composition of the biochar produced were examined by elemental and proximate analyses. The mass fraction of volatiles, oxygen and the ratios of oxygen to carbon (O/C) and hydrogen to carbon (H/C) decreased linearly with pyrolysis temperature. Surface properties of all the biochars produced (SEM morphology, CO2 and N2 adsorption, XPS analysis, Boehm titration, cation exchange capacity (CEC) and ζ-potential) were also studied. The removal of volatiles resulted in the gradual creation of microporosity detectable by CO2 adsorption but which was difficult to detect with N2 adsorption, suggesting that the chars contain micropores mostly less than 1 nm in entrance dimension. The XPS and Boehm titration confirmed that most oxygenated surface functional groups (presence of carbonyl, carboxyl and hydroxyl groups) are gradually removed as pyrolysis temperature increases. The changes in surface charge were studied by ζ-potential measurements and were found to vary directly with the content of oxygenated functional groups. Properties that depend on both surface area and the surface oxygenated functional groups, such as the cation exchange capacity, showed a more complex behavior. The composition of the ash and associated properties such as pH and electric conductivity (EC) were also measured. The total alkaline content increases with pyrolysis temperature leading to higher pHs and ECs.

Evaluation of predictive models for Douglas-fir bark thickness at breast height following 12 biomass harvest treatments

Foresters often require an estimation of bark thickness from a reference height (typically breast height) to accurately estimate the bark or wood volume of a tree. Various models for estimating the bark thickness of interior Douglas-fir (Pseudotsuga menziesii var. glauca) from measured dbh (diameter at breast height) were evaluated. Sample trees were from northern Rocky Mountain mixed conifer stands that had been subjected to four levels of experimental woody biomass harvesting. Among simple linear, nonlinear, and segmented linear mixed effects models, the segmented linear model performed best. A join point (where the linear equations are linked) for the segmentation was statistically detected at approximately 19.0 cm dbh. The join point seems to indicate the size at which juvenile Douglas-fir trees boost the production of bark tissue, perhaps as those trees express dominance over competing understory vegetation. Woody biomass utilization level had no impact on bark thickness, indicating that the bark:dbh relationship does not depend on biomass utilization intensity. The study results enable accurate bark thickness estimation for interior Douglas-fir in this region, and suggest several silvicultural applications for juvenile Douglas-fir stand management.

Selective fractioning of Pseudotsuga menziesii bark and chemical characterization in view of an integrated valorization

The outerbark of Pseudotsuga menziesii was chemically analyzed after selective fractioning into different particles sizes. Fractionation was selective: after grinding, the coarse fraction (>2mm) was enriched in cork and was obtained in higher yield (53.9%).The mean bark chemical composition was, as % o.d. mass: ash 5.9%; total extractives 26.7%; lignin 29.5% and suberin 22.0%. The fine fraction of bark was richer in extractives (31.7%) namely polar compounds soluble in ethanol and water (29.2%). The content in lipophilic extractives was higher in the coarse fraction (5.5%). The polysaccharides contained glucose (65.7% of total neutral monossacharides), mannose (11.8%), xylose (9.0%), arabinose (7.1%) and galactose (6.5%). The ethanol and water extracts contained phenolics, flavonoids, condensed and hydrolysable tannins. The lipophilic extracts were analysed by GC–MS, directly and after saponification, revealing two major compounds: β-sitosterol and tetracosanoic acid. The fine fraction was enriched in extractives and polysaccharides as well as in inorganics, and impoverished in suberin in comparison with coarse fractions.Milling and fractionation may be applied as pre-treatment for Douglas-fir bark utilization, by separation of cork-rich fractions for cork-based products e.g., composites, and phloem-rich fractions for extraction of polar extractives and further processing of the polysaccharide-lignin matrix under a biorefinery approach.

Marigold and Pepper Growth in Container Substrates Made from Biosolids Composted with Carbon-rich Organic Wastes

Composts made from organic wastes have the potential to substitute for peat and bark as components of container growth substrates. Composts for this research were produced in small-scale aerobic bins using biosolids blended with construction debris, storm debris, or horse waste in a 1:3 (v:v ratio). The composts were screened and blended 1:1 (v:v) with douglas fir (Pseudotsuga menziesii) bark to produce substrates. They were compared with a peat–perlite control substrate, a biosolids blend control substrate, and substrates made from a commercial biosolids compost mixed 1:1 with bark and from fiber from an anaerobic digester (dairy manure and food waste) mixed 1:1 with bark. Chemical and physical properties of the substrates were measured before transplanting, and growth, quality, and leaf color of ‘Little Hero Flame’ marigold (Tagetes patula) and ‘Golden California Wonder’ bell pepper (Capsicum annuum) were measured in a replicated greenhouse study comparing the substrates at two rates of nitrogen (N) application. The experimental biosolids composts-bark substrates performed similar to the peat–perlite and biosolids blend controls for growing marigold and pepper. The commercial biosolids compost mixed with bark did not perform as well as the experimental substrates or the controls. Digester fiber-bark was intermediate between commercial biosolids compost-bark and other treatments. Higher N rates improved plant growth and quality across all container substrates in pepper, but had fewer significant effects on marigold. Experimental substrates were coarser texture than the peat–perlite or biosolids blend controls, resulting in higher aeration porosity (AP) and lower water-holding capacity (WHC), but performed well nonetheless under the drip irrigation used in this study. Using locally sourced organic waste materials as container substrates can help capture value from organic wastes and contribute to the sustainability of nursery production practices.

Kinetic modeling of reduction zone in biomass gasification

Gasification of biomass is becoming common technology now a days; it is convenient to apply numerical simulation to the process to save time and energy as compared to the lengthy experimentation.Syngas produced as a result of gasification has many applications. Keeping in view those applications the objective of this work is to maximize the yield of syngas, using five different biomass like bagasse, wood sawdust, douglas fir bark, peanut hull and rice husk. The maximum yield of syngas is calculated using rate equations under isothermal and non-isothermal conditions. For isothermal conditions, the kinetic model is simulated over the temperature range of 1000–1300K by taking a step size 50K to estimate optimum temperature. For non-isothermal conditions, the kinetic equations are solved for heating rate range of 25–75K/s by taking a step size 10K/s to assess optimum value of heating rate.

Management, Morphological, and Environmental Factors Influencing Douglas-Fir Bark Furrows in the Oregon Coast Range

Many land managers in the Pacific Northwest have the goal of increasing late-successional forest structures. Despite the documented importance of Douglas-fir tree bark structure in forested ecosystems, little is known about factors influencing bark development and how foresters can manage development. This study investigated the relative importance of tree size, growth, environmental factors, and thinning on Douglas-fir bark furrow characteristics in the Oregon Coast Range. Bark furrow depth, area, and bark roughness were measured for Douglas-fir trees in young heavily thinned and unthinned sites and compared to older reference sites. We tested models for relationships between bark furrow response and thinning, tree diameter, diameter growth, and environmental factors. Separately, we compared bark responses measured on trees used by bark-foraging birds with trees with no observed usage. Tree diameter and diameter growth were the most important variables in predicting bark characteristics in young trees. Measured environmental variables were not strongly related to bark characteristics. Bark furrow characteristics in old trees were influenced by tree diameter and surrounding tree densities. Young trees used by bark foragers did not have different bark characteristics than unused trees. Efforts to enhance Douglas-fir bark characteristics should emphasize retention of larger diameter trees’ growth enhancement.