Abstract

Increasing restrictions on the use of methyl bromide have created an urgent need to find suitable replacements that are effective in eliminating exotic pest establishments via trade in wood products. Efficacy data for established phytosanitary fumigants have primarily focused on arthropods and nematodes, whereas limited information exists for plant pathogens and fungi relevant to forestry. A rapid screening process was developed to evaluate efficacy and compare relative tolerance to fumigation treatments for a broad selection of relevant fungi under laboratory conditions. Sulfuryl fluoride (SF) fumigations were conducted in 10-liter glass chambers at six target concentrations (40 to 240 mg liter⁻¹) at 15°C and 20°C for 24-, 48-, and 72-hour exposure times against 23 fungal species represented with 35 isolates. Fungi were grown on sterilized barley grain and then distributed in felt-covered borosilicate glass tubes to allow uninhibited gas penetration during fumigation while minimizing the risk of fungal contamination. This allowed simultaneous testing of numerous species and isolates, followed by 100 percent recovery of controls without contamination. Results demonstrate that SF is an effective fumigant for a broad range of fungi. Several fungi and isolates were found to consistently be among the most tolerant to the fumigant treatment. These species may serve as a benchmark for screening SF in fumigations of logs and other wood products. Methods developed here will be useful in efficacy screening of other methyl bromide fumigant alternatives.

Abstract

Development of wood preservatives typically involves laboratory tests using mycelial inoculation and field tests with through-treated small-dimension pine sapwood samples. These preservatives are then commercialized for use also on refractory wood species in Canada and the western United States. A field test was established at two locations in Canada to assess performance of stakes and decks of three species, both untreated and treated with a range of retentions of copper azole type B (CA-B), and two species treated with a range of retentions of alkaline copper quaternary carbonate formulation (ACQ-D). The decking was inspected after 10 years of exposure. CA-B– and ACQ-D–treated boards were generally in excellent condition except at preservative retentions well below standard. Decay was extensive in boards without treatment at both test sites. At one test site, decay was also extensive in preservative-treated white spruce at low retention treated without incising and without end coat. The difference in performance between boards with and without end coat illustrated the beneficial effect of end-cut preservative.

At the ground-contact retention of 3.3 kg/m³ CA-B, stakes of all three species were predominantly sound after 10 years of exposure at both sites. ACQ-D–treated stakes at retentions around 6.4 kg/m³ were sound at one test site, but some stakes showed slight to moderate decay at the other site. Moderate decay was found at retentions below this. Both preservatives were effective against termite attack, but very severe decay and termite attack were present in untreated control stakes of all three species.

Abstract

Scale models of wooden bridge timbers were broken in bending to assess the impact of holes drilled along their length to permit the addition of wood preservatives. The results indicate that the holes have minimal impact. However, the common practice of cutting “daps” on the underside of the beams to accommodate the supporting beams appears to have substantial strength-reducing effects. Railroads could consider using borate ports to improve the life of their bridge timbers and reducing the depth of, or eliminating, daps.

Abstract

The large variation in knot characteristics within and between trees and stands makes proper interpretation of wood properties in the different steps along the forest–to–forest product conversion chain difficult and makes production and use of wood a challenge. Finding good methods and models to interpret the knot characteristics along the different steps of this chain is therefore important. In all, 28 young Douglas-fir (Pseudotsuga menziesii) trees were sampled from four stands with different site indices and tree densities. This gave working material consisting of 189 whorls of knots total. Models predicting knot diameter and sound knot length were developed. Important variables reducing the residual variance were mean annual ring width at breast height, mean annual ring width for different annual ring intervals at breast height, site index, and number of trees per hectare. The study shows that models estimating knot diameter and sound knot length with mean annual ring width for certain annual ring intervals (intervals 6 to 10 and 11 to 15) reduced the residual variance somewhat more than variables describing site index and tree density, respectively.

Abstract

Juniperus scopulorum is a common tree in the lower elevations of the Rocky Mountains, and is often removed in restoration treatments. This work reports on selected mechanical and physical properties of J. scopulorum. Ten trees were felled and processed, and a static bending machine was used to test 162 specimens. Additionally, 82 ovendried specimens were assessed for shrinkage and density. Results show an air-dry modulus of elasticity (MOE) of 4,611 MPa, air-dry modulus of rupture (MOR) of 68,460 kPa, green MOE of 3,846 MPa, green MOR of 46,760 kPa, specific gravity of 0.4184 (green basis), and shrinkage value of 7.956 percent. These numbers suggest several new uses for the wood including highway signage, guardrails, and bioenergy feedstock.

Abstract

Compressed wood panels (CWP) is a biomaterial that can potentially address common issues with fast-growing wood, including low density, high perishability, and low mechanical strength. As wood density is known to significantly affect material properties, this study examines the cellular structure, wettability, physicomechanical performance, water absorption (WA), and dimensional stability of compressed weeping willow wood panels (CWWWP) at various densities. The cellular structure was investigated by a scanning electron microscope, and major physicomechanical properties were also measured, i.e., modulus of rupture, modulus of elasticity, and horizontal shear strength. Contact angle measurements and surface free-energy (SFE) calculations were used to elucidate CWWWP wettability. The experimental results showed that the cellular deformation, composite strength, and volume-swelling efficiency all tended to increase with increasing density. However, both the SFE and WA were negatively correlated with the CWWWP density. This study concludes that higher-density CWWWP, with better mechanical performance and lower WA, is suitable for structural wood products and engineering materials, whereas lower-density CWWWP is suited for use as decorative material because of its lower density and higher SFE, which increases the ease of coating and painting.

Abstract

In response to changes in forest management and conversion practices, concern has arisen that some solid wood products manufactured today exhibit decreased strength and stiffness properties (modulus of rupture [MOR] and modulus of elasticity [MOE]) compared with those manufactured in the past. This study addresses those concerns by comparing the mechanical properties of wood utility crossarms sampled in 2015 with those of a similar sample of crossarms from 1995. Destructive bending tests were performed on crossarm samples of southern pine (Pinus spp.) and Douglas-fir (Pseudotsuga menziesii). These data were compared with data from a similar 1995 study by H. M. Barnes and J. E. Winandy (pp. 30–38, in Proc. 97th Annu. Meet. AWPA, 2001). The results showed a statistically significant difference (7.1% reduction) at the α = 0.01 level of mean MOR in southern pine and a statistically significant difference (13.3% reduction) at the α = 0.01 level of mean MOE in Douglas-fir. Distribution analyses also suggested a reduction of strength performance in the lower percentiles for both species groups between the two studies.

Abstract

The development of portable unilateral magnetic resonance (UMR) devices permits nondestructive characterization of wood moisture content (MC) in the field. In this study, six Picea mariana Mill. logs were measured. UMR measurements of MC were taken in four different spots displaced 15 cm from the end of each log. UMR measurements were also taken at the midpoint longitudinally for three of the six logs.

The end goal of this study was to demonstrate a viable approach to estimating the whole-sample MC in the field. In the case of the species studied, there is a significant difference in MC between sapwood and heartwood regions. The sapwood MC is approximately three times greater than the heartwood MC. However, the volume of heartwood is greater than sapwood in wood logs. The sapwood region contains most of the water; therefore a measurement in the sapwood, coupled with sapwood-to-heartwood volume proportions and an estimate of heartwood MC, provide a viable estimate of bulk MC of logs.

Results indicate that both measurement spots (15 cm displaced from the end and at the midpoint longitudinally) give good predictions of log MC. The UMR measurement signal-to-noise ratio decreases and variability in the total sapwood signal of the four spots, displaced 15 cm from the end, increases as drying progresses. The increase in variability is because of the appearance of a drying front at some measurement spots. The UMR device and technique provide a good tool to measure MC of logs in the field.

Abstract

Large amounts of construction wood were generated as disaster waste during the 2011 Tōhoku, Japan, earthquake and tsunami. The construction wood waste had been immersed in seawater and thus contained salts. When the saltwater-immersed wood was incinerated during restoration efforts, dioxins harmful to human health were likely produced. Thus, it is necessary to determine if wood waste had been exposed to saltwater before combustion. Furthermore, online recycling of coastal wood debris containing saltwater could be applied to the disposal of industrial wastes. Near-infrared (NIR) spectroscopy was used to distinguish saltwater-immersed wood. Three wood species, Cryptomeria japonica, Chamaecyparis obtuse, and Larix kaempferi, which are commonly used in the construction of Japanese houses, were prepared. Immersion time was changed from 24 to 72 hours to investigate the time-dependent change. NIR spectra were obtained from wood samples before and after immersion in seawater and were used in classification analysis by soft independent modeling of class analogy (SIMCA). For SIMCA at immersion time of 24 hours, the percentage of correct classification was for 94 percent for Cryptomeria japonica, 96 percent for Chamaecyparis obtuse, and 92 percent for Larix kaempferi. There is no difference in the classification accuracy by the wood species and immersion time. Moreover, another classification analysis (partial least-squares discriminant analysis [PLS-DA]) was performed to raise the classification precision. The result of PLS-DA was superior to SIMCA. NIR was a powerful tool in identifying saltwater-immersed wood samples and indicated the possibility of using it at the wood-recycling factory.

Abstract

Nonindustrial private forest (NIPF) landowners own 62 percent of Virginia's forestland and determine the likelihood of its harvest and utilization. As many studies have found, NIPF landowners are diverse in management goals, and many factors can affect a landowner's willingness to harvest. Although many landowner surveys have been conducted, adequate information regarding the characteristics of NIPF landowners and their willingness to harvest in Virginia is lacking. Given new markets for wood in the state, there is considerable interest in examining fiber supply availability to determine the sustainability of an expanded forest and renewable energy industry. Landowners and their willingness to supply timber play a vital role in future resource availability. During 2014, a survey was mailed to 3,000 NIPF landowners who owned at least 10 acres of wooded land. Using a base question of willingness to harvest, groups across the state were compared to determine factors that affect their behavior. We found that the variables income, age, forested acres owned, and forest management were all significant and positively related to willingness to harvest. Knowledge of the characteristics of forest landowners and their attitudes toward harvesting can guide efforts to engage more landowners.

Abstract

The forest products industry is a major contributor to the US South's economy. With the global recession of 2007 to 2009 and associated downturn of the US housing market and other construction activities, the forest products industry's production and associated contribution to federal, state, and local taxes have been severely affected. The changes in tax contributions of these events for the products industry (i.e., lumber and wood products, paper and allied products, and wood furniture) were assessed using Impact Analysis for Planning software and 2009 data. Thirteen states in the US South were selected for this study. The results of tax contributions in 2009 were then compared with those made in 2001. Among the forest products industry sectors, tax contributions increased only for the paper and allied products sector from 2001 to 2009. Thus, this study documents the tax contributions of the forest products industry and how they can change over time in response to changes in the sector's economic activity. This study can help policymakers predict fluctuations in tax contributions and plan accordingly to stabilize and/or improve tax revenues.

Abstract

Although the hardwood timber market is an important segment of the forest industry in the United States, little attention has been paid to modeling hardwood stumpage and lumber markets. Based on the annual data series from 1955 to 2014, we estimate simultaneous demand and supply models of the hardwood sawtimber stumpage market in Louisiana. A permanent structural break in 1993 is detected in the hardwood sawtimber stumpage market, and the modified cointegration test and structural vector error correction approach are used to estimate the demand for and supply of hardwood sawtimber stumpage. The results show that own-price elasticity values in both the demand and the supply equations are inelastic in the long run. Hardwood and softwood sawtimber are found to be substitutes. Moreover, the softwood timber market always leads in the feedback adjustment process and can help predict the hardwood timber price in Louisiana.

Abstract

Policies to constrain carbon emissions, such as the carbon tax, have made low-carbon trade competitiveness (LCTC) a significant tendency in research concerning industrial international competitiveness. However, few empirical studies have analyzed the influence of a carbon tax on LCTC. We combined the trade competitiveness index and industrial carbon productivity to construct an industrial LCTC index that can analyze carbon emissions performance and international competitiveness. We then used the LCTC index to build a dynamic panel model with its potential factors, which was estimated by system generalized method of moments method based on panel data of 38 countries between 1995 and 2009. We found evidence that a carbon tax exerts an indirect positive influence on the LCTC of the paper-making industry by stimulating technological innovation. The policy implications suggest that, considering the increasingly intensified countermeasures against carbon leakage, governments should strengthen the promotion mechanism of technological innovation to guarantee the positive effects of a carbon tax.

Abstract

The feasibility of applying an innovative process to manufacture composite decking boards with quartersawn or starsawn southern pine lumber bonded with phenol resorcinol formaldehyde (PRF) and polyurethane (PU) adhesives was studied. It was feasible to make quatersawn-based composite decking panels with possible improved surface qualities. Accelerated aging tests showed that composite quartersawn decking samples were more resistant to aging than flatsawn decking samples in terms of shear strength, especially after exposure to 12 wet–dry aging cycles. Compared with the PRF adhesive, the PU adhesive resulted in greater initial dry shear strength but had lower shear strength after the accelerated aging test. Furthermore, the amount of wood failure increased for the PRF-bonded samples and decreased for the PU-bonded samples after accelerated aging tests. Compared with solid quartersawn decking boards, the quartersawn composite decking boards had the same modulus of rupture and modulus of elasticity.

Abstract

At certain concentrations, volatile organic compounds (VOCs) may harm people's health. This article introduces a new rapid detection method for testing VOCs released from three-layer plywood. A Micro-Chamber/Thermal Extractor was used to analyze the effect of environmental factors on release characteristics of VOCs in the stable phase, and a single-factor experiment was used to analyze the release of VOCs under different temperatures, relative humidity levels, and ratios of air exchange rate–to–loading factor, by using the rapid sampling device together with gas chromatography–mass spectrometry (GC-MS). Results showed that aromatic hydrocarbons, alkanes, and esters were the main components of VOC emissions released from three-layer plywood. The percentage of VOC components in the stable phase changed as the single factors changed. Temperature has the greatest impact on the percentage of VOC components. The VOC concentration increased as temperature and relative humidity increased but decreased as the ratio of air exchange rate–to–loading factor increased. Temperature had a greater impact on VOC release from three-layer plywood than did relative humidity or the air exchange rate–to–loading factor ratio.

Abstract

Because of the possibility of harmful formaldehyde emissions from industrial-produced wood composites, the influence of temperature, relative humidity, and frequency of ventilation on formaldehyde emission from particleboard, plywood and fiberboard respectively, were investigated in this article. An improved generally applicable model for calculating the formaldehyde emission from wood composites was established by using the iteration method, a double exponential attenuation model, and mass transfer theory. The model parameters for the emission of formaldehyde from wood composites are also discussed in this article. It is concluded that a high-temperature or high-humidity environment will promote the emission of formaldehyde from wood composites. The process of emission of formaldehyde from wood composites can be divided into quick-release, slow-release, and release saturation phases. The formaldehyde concentration can be predicted from the formaldehyde mathematical model, and the maximum difference between observed and predicted formaldehyde concentrations is less than 15 percent under different general environmental conditions.

Abstract

In this study, eucalyptus wood was subjected to thermal treatment with super-heated steam under various conditions. The effects of temperature and exposure time on the functional groups and degree of cellulose crystallinity of the eucalyptus wood (Eucalyptus grandis × Eucalyptus urophylla) were analyzed. The results showed that the thermal treatment caused significant changes in the chemical composition and structure of wood. The Fourier transform infrared spectroscopy (FTIR) absorption peaks of the hydroxyl group decreased from 3,425 to 3,250 cm⁻¹ for all thermally treated samples. Higher treatment temperature and extended exposure led to the lower methyl levels, with almost no methyl present at 220°C. The aromatic ring first increased and then decreased with increasing temperature and exposure time. The carbonyl group maintained the same intensity, with small fluctuations, across the different thermal treatment conditions. Compared with the untreated wood sample, the X-ray diffraction peak position of thermally treated samples shifted slightly left from 22.02° to 21.06°, and the distance between crystal planes increased. The degree of cellulose crystallinity of eucalyptus wood was affected significantly by treatment temperature with a confidence level of 99 percent.