Green Wood Research Articles

Seasoned or green? Radial cracks analysis as a method for identifying the use of green wood as fuel in archaeological charcoal

For several years, sociological questions have been central in anthracology. The development of socio-economic approaches based on the recognition of anatomical signatures in wood has made it possible to focus on topics related to firewood use and its management. The presence of radial cracks (RC) on archaeological charcoal is generally interpreted as the result of the burning of green wood. The present study proposes a verification of this theory by the experimental combustion of seasoned and green wood of Scots Pine ( Pinus sylvestris L.). Experimenting with this species was a research priority since it was the dominant taxon (representing 80–100% of the charcoal remains) identified in the Palaeolithic European sites under consideration. The experiments were conducted using two different methods: (i) inside a muffle furnace that allowed us to control the combustions, but in which the combustion process is quite different from most archaeological situations and (ii) in an open fireplace, less controllable but closer to the archaeological conditions. The systematic quantification of the number, length and width of the radial cracks (RC) measured on the transversal sections of the experimental samples demonstrates that (i) radial cracks occur independently of the moisture content of the wood before the combustion (on green and seasoned wood); (ii) however, the average number of radial cracks (RC/cm 2) allows distinguishing seasoned from green wood; (iii) in the muffle furnace, the size of the RC appeared to be a good criterion for discriminating seasoned and green wood, but this observation was not confirmed by the open-air combustions. Our results clearly show that the appearance of radial cracks is not diagnostic of the combustion of green wood. Nevertheless, the number of radial cracks (RC/cm 2) could represent a new method that might help identifying the combustion of green wood in archaeological charcoal samples.

Temperature Thresholds and Degree-Day Model for Marmara gulosa (Lepidoptera: Gracillariidae)

The developmental thresholds for Marmara gulosa Guillén & Davis (Lepidoptera: Gracillariidae) were investigated in the laboratory by using 17, 21, 25, 29, and 33 degrees C. The lowest mortality occurred in cohorts exposed to 25 and 29 degrees C. Other temperatures caused >10% mortality primarily in egg and first and second instar sap-feeding larvae. Linear regression analysis approximated the lower developmental threshold at 12.2 degrees C. High mortality and slow developmental rate at 33 degrees C indicate the upper developmental threshold is near this temperature. The degree-day (DD) model indicated that a generation requires an accumulation of 322 DD for development from egg to adult emergence. Average daily temperatures in the San Joaquin Valley could produce up to seven generations of M. gulosa per year. Field studies documented two, five, and three overlapping generations of M. gulosa in walnuts (Juglans regia L.; Juglandaceae), pummelos (Citrus maxima (Burm.) Merr.; Rutaceae), and oranges (Citrus sinensis (L.) Osbeck; Rutaceae), for a total of seven observed peelminer generations. Degree-day units between generations averaged 375 DD for larvae infesting walnut twigs; however, availability of green wood probably affected timing of infestations. Degree-day units between larval generations averaged 322 for pummelos and 309 for oranges, confirming the laboratory estimation. First infestation of citrus occurred in June in pummelo fruit and August in orange fruit when fruit neared 60 mm in diameter. Fruit size and degree-day units could be used as management tools to more precisely time insecticide treatments to target the egg stage and prevent rind damage to citrus. Degree-day units also could be used to more precisely time natural enemy releases to target larval instars that are preferred for oviposition.

Equilibrium moisture content (EMC) in Norway spruce during the first and second desorptions

Abstract It is a commonly accepted notion that the equilibrium moisture content (EMC) of wood at a given relative humidity (RH) is highest during initial desorption of green wood due to an irreversible loss of hygroscopicity during the 1st desorption. The basis for this notion is investigated by assessing how drying and saturation procedures influence the differences between the 1st and the 2nd desorption curves for Norway spruce (Picea abies (L.) Karst.) sapwood. The study establishes 1st and 2nd desorption isotherms for a variety of initial conditions and it covers the RH range from 60.1% to 99.9%. The state of the water is not affected by oven-drying and rewetting as demonstrated by time domain low field NMR relaxometry. The results challenge the conclusions of earlier studies and indicate that in these studies the 2nd desorption was initiated at much too low EMC and therefore fails to describe a boundary desorption isotherm. Instead, it becomes an intermediate desorption isotherm starting at the adsorption boundary curve and crossing over to eventually meet the desorption boundary curve. The results also show that vacuum drying at room temperature only gives a modest loss of hygroscopicity compared to the green state. Conversely, oven-drying at 103°C results in a more significant loss of hygroscopicity, except for RH above 96% where an increase in EMC surprisingly is seen.

Estimated nitrogen use efficiency, surplus, and partitioning in young apple trees grown in varied organic production systems

A certified organic apple ( Malus × domestica Borkh.) orchard was established to study the interaction of ground cover management systems (GMS) and nutrient sources (NS) on nitrogen (N) use efficiency and N surplus in the Southern U.S. for three years. Trees treated with green compost (GC) and wood chips (WC), regardless of the NS, had greater N accumulation and leaf N use efficiency compared to the shredded paper or mow-and-blow treated trees. The WC-treated trees had comparably low N surplus relative to the GC trees that induced more [NO 3 −] in soil or soil solution in the rooting zone in September in year 3. GC trees had the highest [NO 3 −] mineralization in the soil during winter. GMS had greater overall effects on the tree response variables than did the NS.

Influence of combined hydro-thermal treatments on selected properties of Turkey oak (Quercus cerris L.) wood

A combined effect of steaming and heat treatment was imposed on green Turkey oak wood, both for sapwood and heartwood. Steaming was carried out in an autoclave at 100–120–130°C whereas heating was carried out in an oven for 2 h at 120–180°C. Equilibrium moisture content at dry, intermediate and moist state both in desorption and adsorption, swelling, cup, twist, color change, and spectral reflectance measures were registered. Swelling and water absorption decreased due to the hydro-thermal treatment. During adsorption, heartwood showed a higher hygroscopic inertia compared to sapwood and this difference increased with temperature. Cup increased with temperature in the steaming process. Twist seemed to be affected more by quality of original trunks than treatments. The wood color was more sensitive at a steaming temperature of 130°C combined with heat treatment at 180°C. Transitional treatments assured more reliable results on homogenization of hue between sapwood and heartwood.

Discussion on Application Prospect of Starch-Based Adhesives on Architectural Gel Materials

Starch in architecture material industry has been paid much attention for its inexpensive price, good characteristics of bonding, forming property and good biodegradability. In the paper, the research progress of starch on architectural constructional materials is concluded in five aspects of green wood adhesive, coatings binder, mortars preparation, concrete water reducing agent and ceramic production. It is suggested that the new starch-based architectural gelled material should be prepared and replaces the traditional gelled material —cement in the future for the reasons of application limited of starch and problems caused by cement producing process, and the application prospect of starch-based adhesives in related field is also proposed in the end.

Effect of steaming treatment on resistance to footprints in Turkey oak wood for flooring

Turkey oak (Quercus cerris L.) wood has some technological limitations that reduce its market value despite its great potential. This study evaluated the effect of indirect steaming on the resistance to footprints of Turkey oak wood in order to assess its use as parquet. Steaming treatments were carried out on green wood at 120°C and for 24 hours, while a drying process was carried out on all boards at 63°C, 120 mm Hg of vacuum for 34 days. Good elastic restoration was observed for untreated wood, while for treated wood the resistance to footprints was higher in the radial than in the tangential direction. By contrast, a significant negative effect on the elastic recovery of the original dimensions was found which was higher in radial than in tangential direction, when a load was conducted on steamed wood.

Predictions of wood density and module of elasticity of balsam fir (Abies balsamea) and black spruce (Picea mariana) from near infrared spectral analyses

The predictions of properties for wood disc average are seldom reported, and they are important for sorting out logs based on their quality. The minimum near infrared (NIR) spectra required to predict wood disc average properties would also be of critical importance. In this study, calibration and prediction models for wood disc average properties were developed using NIR spectral data for balsam fir (Abies balsamea (L.) Mill.) and black spruce (Picea mariana (Mill.) B.S.P.) samples collected from 14 different sites across Newfoundland, Canada. The calibration was done against area-weighted average wood properties determined by SilviScan. NIR spectra were collected in 18 mm increments from the radial–longitudinal face of green and oven-dried samples. Results showed that using NIR spectra from three spots per wood strip was sufficient for the modeling and prediction for density and module of elasticity (MOE). The coefficients of determination ranged from 0.76 (MOE of green wood samples) to 0.88 (density of oven-dried wood samples). However, the microfibril angle (MFA) cannot be well predicted from either green wood or oven-dried wood NIR spectra. Our results further showed that the NIR spectra collected from oven-dried wood samples gave better calibration and prediction than those collected from green wood samples.

Extraction, Characterization and Utilization of Organosolv Miscanthus Lignin for the Conception of Environmentally Friendly Mixed Tannin/Lignin Wood Resins

Lignin was extracted from Miscanthus × giganteus using two procedures: an aqueous-ethanol organosolv treatment and a two-step process involving a dilute acid pre-soaking step followed by an aqueous-ethanol organosolv treatment. The organosolv lignin was subjected to a comprehensive structural characterization by 13C and MALDI-TOF MS and used for the formulation of a green wood adhesive prepared with 100% natural resins. The best formulation was composed of 60% of mimosa tannin and 40% of glyoxalated lignin extracted using a 1-step organosolv treatment. This formulation, when applied to wooden test panels yielded good internal bond strength results, which was good enough to pass relevant international standard specifications for interior-grade panels.

Microbial respiration as an indication of metal toxicity in contaminated organic materials and soil

The effect of heavy metals on microbial respiration in organic materials used as soil amendments was evaluated to assess the stability of the materials. Solutions of Pb (II), Cu (II) and Zn (II) at rates of 5, 10 and 50 mg metal g −1 were added to green waste compost, peat, coir and wood bark. Metal toxicity led to a significant decrease in carbon dioxide evolved by the contaminated materials, up to 80% less at the highest rate of addition compared to the untreated material. There was a significant negative correlation between the organic carbon content of an amendment and the inhibition of CO 2 evolution by all three heavy metals. There was also a significant negative correlation between an amendment's cation exchange capacity and the inhibition of CO 2 evolution caused by Cu and Zn. The ability of the organic materials to enhance respiration in a soil from the vicinity of a Pb/Zn mine was also evaluated, by applying them to the soil at rates of 1, 10 and 20%. CO 2 evolution from the contaminated soil was enhanced significantly by the addition of all of the amendments, with coir causing up to 90% enhancement at high levels of addition.

Worldwide correlations of mechanical properties and green wood density

The density of wood is highly correlated with the ability of stems and roots to resist bending or twisting, which is important for evaluating the mechanical behavior of trees. It also provides a measure of carbon storage, which is an important variable in modeling ecosystem processes and tree construction costs. However, most measurements of the density and mechanical properties of wood have little direct bearing on understanding the biomechanics of living plants because they are based on kiln- or air-dried samples. • Here, we present and analyze the relationships between four important mechanical properties (Young's modulus, the modulus of rupture, and the maximum strength in shearing and in compression) and the density of green wood (i.e., wood at 50% moisture content) from a worldwide, taxonomically broad spectrum of 161 species. • These data indicate that each of the mechanical properties disproportionately increases across species with increasing green wood density, i.e., stems composed of denser green wood are disproportionately stiffer and stronger than stems with equivalent cross-sections composed of less dense green wood. • Although denser wood may have a higher carbon construction cost, the mechanical benefits of denser woods likely outweigh the extra cost.

Bioslurry as a Fuel. 3. Fuel and Rheological Properties of Bioslurry Prepared from the Bio-oil and Biochar of Mallee Biomass Fast Pyrolysis

This study investigates fuel and rheological properties of bio-oil/char slurry (i.e., bioslurry) fuels, which were prepared by mixing bio-oil with different concentrations of biochar. The bio-oil and biochar were produced from mallee fast pyrolysis at 500 °C. The excellent grindability of biochar enables desirable particle size reduction of biochar into fine particles, which can be suspended into bio-oil for the preparation of bioslurry fuels. The bioslurry fuels have desired fuel and rheological characteristics, which meet the requirements for combustion and gasification applications. Dependent upon biochar loading, the volumetric energy density of bioslurry is up to 23.2 GJ/m3, achieving a significant energy densification (by a factor >4) in comparison to green wood chips. Bioslurry fuels with high biochar concentrations (11−20 wt %) show non-Newtonian characteristics with pseudo-plastic behavior. The flow behavior index, n, decreases with an increasing biochar concentration. Bioslurry with higher biochar concentrations also demonstrate thixotropic behavior. The bioslurry fuels also have low viscosity (<453 mPa s) and are pumpable at both room and elevated temperatures. The concentrations of Ca, K, N, and S in bioslurry are below the limits of slurry fuel guidelines. Overall, the results in this study suggest that bioslurry fuels achieve substantial volumetric energy densification and are suitable fuels for combustion and gasification applications.

Green surfboards: Investigation of product biodegradability at end of life

As the world becomes more environmentally conscious, companies find ways to make products and manufacturing processes greener. This work examines an innovative surfboard product that uses bio-based fiber-reinforced polymers to address product disposal issues and to lower the toxicity associated with some of its components and manufacturing processes. The goal of this work is to characterize the biodegradability of the “green” surfboards at end of life, focusing on the fiber-reinforced composite laminate covering the surfboard and the core of the board. Different laminate types, with various combinations of resins (polyester, epoxy and a bio-resin) and reinforcing fibers (fiberglass, organic hemp and organic cotton), were tested. Polyurethane core was compared with the green alternative balsa wood core. Degree and rate of biodegradability of materials were evaluated by measuring weight change and material hardness over 56 days under controlled composting conditions. The results suggest that the resin compo...

Is vitrification in charcoal a result of high temperature burning of wood?

The term ‘vitrified’ is used to describe the glassy appearance of some charcoals recovered in the archaeological record. It has been generally considered that this phenomenon is a result of wood being subjected to high temperatures similar to the role of temperature in the formation of glass and pottery. Charcoals displaying characteristics of vitrification from three distinct archaeological contexts were analysed using reflectance microscopy to determine their temperature of formation. Charcoal was also generated in laboratory charring experiments at temperatures of 900–1100 °C for durations of 1, 6, 12 and 24 h to determine if subjection to high temperature led to vitrification. None of the laboratory-produced charcoals displayed characteristics of vitrification. Mean random reflectance of the vitrified archaeological fragments indicated temperature of formation from 310 to 530 °C. A charring experiment was also conducted, at 500 °C for 6 h, using green wood with some bark attached, and added sugars, but no evidence of vitrification was seen. Therefore vitrified charcoals do not result from high temperature charring or primarily from the use of green wood.

Finger jointing of green Black pine wood (Pinus nigra L.)

This research work presents a study on the finger jointing of green Black pine wood (Pinus nigra L.) using a phenol resorcinol formaldehyde adhesive. The effect of finger joint orientation (vertical or horizontal fingers) was also examined. In general, the results from the measurements of modulus of rupture and modulus of elasticity of green glued finger-jointed specimens indicated that green gluing of Black pine wood is feasible.

Study of acoustic wave propagation through the cross section of green wood

An experimental approach was used to model stress wave propagation in green wood (Douglas fir). Based on the assumption that wood is an orthotropic material, the stress wave velocity through the cross section was calculated using plane strain motion equations. The experiments were carried out in two steps under axial restraint, while the wave propagation time was measured on discs and bars sliced from the discs. Mechanical and physical properties were determined in free vibration. The results showed a significant difference in propagation velocity between waves propagating throughout the whole disc volume and guided waves in bars. The acoustic anisotropy of green wood is discussed and the stress wave form simulation is presented. Good agreement between the simulation and experimental results was obtained.

Predicting pulp yield and pulp productivity of Eucalyptus dunnii using acoustic techniques

Summary The economics of kraft pulping are influenced by variation in wood density and chemistry, or their product, pulp productivity. The ability to predict basic density, pulp yield or pulp productivity before harvest would provide an economic advantage to the grower or processor. Acoustic velocity in green wood is correlated with both basic density and pulp yield, offering potential for rapid screening. We explored relationships between acoustic velocity, density, pulp yield and fibre length using data from Eucalyptus dunnii plantations in northern NSW, Australia. Acoustic velocity measured on logs accounted for 27% of the variation in pulp yield and 50% of variation in pulp productivity. The strong relationship between fibre length and pulp yield is proposed as a possible causal mechanism. A threshold acoustic velocity of 3.65 km s−1 was defined as the point at which logs would produce at least 250 kg of dry pulp per cubic metre of green wood. Removal of the worst 25% of logs, based on velocity, would give a 2.2% gain in pulp productivity which equates, in turn, to an additional 6.2 kg of pulp produced from every cubic metre of green wood.

Evaluating Warp of 2 by 4s Sawn from Panels Produced through Green Gluing Dimension Lumber from Small Ponderosa Pine Logs

Overstocked small-diameter softwood timber in western US forests has created a serious forest health and fire hazard, and the costs of removing this material are high. One way to lower costs is to reduce loss because of warp on lumber sawn from these small logs. Using a green-gluing process, standard 38 by 89-mm (nominal 2 by 4-in.) pieces (2 by 4s) ripped from pressed panels of edge-glued (edge-glued-and-rip [EGAR]) boards sawn from small ponderosa pine (Pinus ponderosa) logs were evaluated for warp reduction. Material was bonded at high moisture content (MC) to simulate lumber freshly sawn from water-saturated logs and examine potential MC effects on wood–wood bonding. We selected a liquid, one-component, fast-curing, cold-setting polyurethane for green gluing wood. Results showed statistically significant reduction in bow (P &lt; 0.001) and twist (P &lt; 0.001) and no statistical difference in crook (P = 0.321) for EGAR boards compared with conventional 2 by 4s before planing. After planing and equilibrating, EGAR boards showed statistically significant increases in crook (P &lt; 0.001) and bow (P &lt; 0.001) but maintained a statistically significant reduction in twist (P &lt; 0.001). Lumber quality decreased after planing and equilibrating to 12 percent MC. Because of high MC in flitches during the green-gluing process, bondline failures sometimes occurred, distorting the final results. High amount of bondline failure after planing and equalizing indicates this process is unfeasible as tested. Greater MC control during green gluing may reduce warp to allow more effective utilization of these small logs.

Physical properties of burnt timber, with special focus on the drying performance

Burnt wood has been found to perform different from sound (green) wood when dried together, but also with regards to other physical and mechanical properties. In this study the drying performance of wood burnt to different degrees in recent plantation fires was investigated, and the physical, chemical and wood anatomical properties of these different wood types were determined. Different cell structure and chemical composition due to thermal degradation could be observed as well as different drying performance and variation in mechanical properties. An explanation for the deviant drying performance was attempted with the observed structural changes.

Soil metal immobilization and ryegrass uptake of lead, copper and zinc as affected by application of organic materials as soil amendments in a short‐term greenhouse trial

AbstractGreen waste compost, peat, coir and wood bark were applied to metal‐contaminated mine waste at the rates of 1%, 10% and 20% on dry weight basis, and perennial ryegrass grown over a period of 6 weeks. Addition of amendments led to increased biomass yield in all soils when compared with the non‐amended soil. EDTA extractable Pb, Cu and Zn was significantly reduced in amended soil, while leaf and root metal concentrations were also significantly reduced by the application of amendments, especially at applied rates of 10% and 20%. Coir, green waste compost and wood bark stood out as amendments which were consistent in reducing soil extractable and plant tissue Pb, Cu and Zn; while peat rates above 10% enhanced solubility of Cu and Zn because of a lowering of the soil pH.