Over the past 20 years, the mountain pine beetle (Dendroctonus ponderosae) has caused considerable tree mortality across the Rocky Mountain region of the western United States. Although the operational and cost impacts of dead timber are generally well known in the sawmill industry, there remains a need to better understand the impact of large-scale outbreaks on the industry at local and regional scales. Using an expert opinion survey of sawmill managers and procurement staff, this study quantified the relative importance of various cost and operations factors related to harvesting and processing beetle-killed timber in Montana. Respondents reported an average log supply of trees in the red or gray stage of mortality as 24.5 percent of log supply from 2010 to 2014, but this dropped to 5.8 percent by 2015. Cracking and checking were perceived as having the highest negative impact on log value, while waste in milling and breakage of logs in handling were ranked highest for milling operations. For a typical lodgepole pine stand, the volume estimated as sawlogs showed a 15 percent decrease between green and red stages and a 50 percent decrease between red and gray stages, with most of the volume change moving into the pulpwood category. Total average cost increases from green to gray for logging, loading and hauling, and sawmilling were 43, 46, and 46 percent, respectively. Results generally support known relationships between defects, costs, recovery, and value, with some interesting departures with regard to blue stain and equipment maintenance.Abstract
Typhoon Melor, which occurred in October 2009, damaged much of the forest in the eastern region of Japan's Aichi Prefecture. The damaged trees were primarily planted Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa) between 40 and 60 years old and were intended for use as structural lumber. The purpose of this study was to investigate the usability of damaged trees for structural lumber. First, the state of the damaged forests was assessed, and the occurrence of compression failure (CF) in logs and lumber from damaged trees was surveyed. The strength properties of the lumber and glued laminated timber of both species were then determined, and usage-related issues for each species were investigated. The study found that the majority of damaged forests had a high stand density and indicated a high diameter at breast height–to–height ratio. The most common damage type was overturned. The rate of CF occurrence in damaged logs and lumber from damaged trees, in logs with the bark on, was highest in those that had suffered from bending. For lumber, the rate was highest in inclined and bending cases, and there were also a few instances in overturned cases. In lumber from damaged trees, a higher Young's modulus was slightly associated with a higher rate of CF occurrence. In terms of the strength properties of lumber from damaged trees, lumber in which the postprocessing surface showed no CF exceeded the standard strength for both species. The properties of lumber in which minute CF was visible on the surface were similar to lumber without CF for Japanese cedar, but Japanese cypress lumber with visible CF exhibited a failure morphology that failed within the elastic range, and most specimens fell short of standard strength. In addition, laminae cut from damaged trees were processed into glued laminated timber, using laminae on which CF could not be seen on the surface. These bending properties were compared with those of glued laminated timber processed from laminae made from normal trees. This comparison showed that the strength of both was similar in the Japanese cedar, whereas in the Japanese cypress, the bending strength (modulus of rupture) of the damaged glued laminated timber was significantly lower than that of normal trees.Abstract
Relationships between static bending modulus of elasticity (MOE) and SilviScan (SS) properties (SilviScan MOE [MOESS], specific gravity, and microfibril angle) were explored. Seventy-three clearwood specimens (25 by 25 by 406 mm) were cut from thirty-two 33-year-old loblolly pine trees. Relationships were calculated between MOE and MOESS (R2 = 0.77); however, MOESS, calibrated using sonic resonance, averaged 25 percent higher than static MOE. Calibrating MOESS to static MOE instead of sonic resonance MOE resulted in similar prediction performance (R2 = 0.77), but more importantly approximately equal prediction values. The results demonstrate the importance of properly utilizing SilviScan information for predicting loblolly pine properties in static bending.Abstract
Wisconsin's forest products industry relies on a consistent supply of sustainably produced timber for its mills; however, recent research suggests significant seasonal variation in timber sale availability. We conducted a survey of Wisconsin mills to examine their procurement practices and assess how seasonal timber harvesting restrictions (STHRs) affect the forest products industry. Fifty-seven mills responded to the survey, which represented a 40 percent response rate. Respondents processed approximately 75 percent of the state's annual roundwood production. The average procurement radius ranged from 75 miles for small sawmills to over 120 miles for pulp mills. Peak inventory levels exceeded 30 days during each quarter for both pulp mills and sawmills, and peak inventory levels during the first quarter exceeded 60 days. Respondents reported that STHRs were common in the state and mills had adjusted their procurement practices in response. Pulp mills estimated that STHRs cost each firm an average of nearly $2.7 million annually, or $4.93 ton−1 of wood purchased during the year, whereas small sawmills reported average additional costs of $188,888 per firm ($10.33 ton−1). Seasonal weight limits on public roads, oak wilt restrictions, and access and transportation restrictions on individual timber sales were reported to have the greatest impact on mills. Continued cooperation is needed among foresters, landowners, and the forest industry to apply STHRs in a manner that protects the forest resource while maintaining a consistent and sustainable supply of timber to the forest industry.Abstract
Korea and other countries have a high ratio of small-diameter logs in the harvested log volume. Hence, using these small-diameter logs as structural materials is an important issue. The lumber obtained from small-diameter logs generally has small cross-section dimensions and is mostly juvenile wood, resulting in inferior strength performance. In this research, a laminating process was developed for effective utilization of small-diameter logs as structural materials, and eight types of laminated beams and eight types of laminated columns were manufactured by the vertical and horizontal laminations with square cross-section timber. The laminated members were composed of laminated square timber obtained from small-diameter logs and were reinforced by square timber or lamina obtained from large-diameter logs. The laminated members were evaluated for their bending and axial compression performance. As a result, the beam exhibited an increase in bending Young's modulus of 63 percent and bending strength of 77 percent. Additionally, the column's axial compression performance indicated a positive effect on compression Young's modulus, where a 158 percent increase was found. Furthermore, when Johnson's equation was used to determine the critical stress, the value was close to the yield stress. In contrast, Euler's equation led to overestimation of the capacity as the slenderness ratio became smaller, which indicated that the application of Johnson's equation may be preferable. Therefore, a combination of small-diameter logs and large-diameter logs provided increased strength and rigidity performance, indicating the possibility of an effective use of small-diameter logs.Abstract
Phytophthora ramorum is an increasingly important tree pathogen in northern California and southern Oregon. While it has the greatest effect on tanoak, it can infect a wide range of tree species, including Douglas-fir. Oregon has instituted a quarantine area to slow the spread of this pathogen, and there are concerns that further restrictions may be imposed on log movement, including those of Douglas-fir. The potential for using boron as a log treatment to limit P. ramorum was evaluated. While boron either alone or in a glycol solution was capable of moving into the bark, there was no evidence that it could move further into the sapwood. The results suggest that bark removal would be necessary for the use of boron as a mitigation agent for the spread of P. ramorum.Abstract
Effect of Blue Stain on Bond Shear Resistance of Polyurethane Resins Used for Cross-Laminated Timber
The effect of blue stain on shear strength of cold-set polyurethane resin (PUR) bonds was investigated using lodgepole pine lumber with varying degrees of stain and two different wood grain orientations. While blue stain was associated with definite differences in wood permeability, it had no negative effect on shear strength or wood failure percent. The results indicate that blue stain will not adversely affect bond strength of PUR bonds.Abstract
Nano-Ag/TiO2 exhibits effective antimicrobial activities; however, its tendency to aggregate limits its application in wood products for improved antimold properties. In this study, nano-Ag/TiO2 was modified by a silane coupling agent (γ-aminopropyltriethoxysilane [KH-550]) and then loaded into wood via vacuum impregnation. The effects of KH-550 concentration, Ag/TiO2 concentration, reaction temperature, and incubation time on the antimold rate, loading amount, and leach resistance for wood materials were investigated. Results showed that the antimold rate, loading amount, and fixation rate of mold-proof–treated wood was strengthened by KH-550 modification. The binding affinity and surface energy of nano-Ag/TiO2 was reduced, and the dispersivity of nano-Ag/TiO2 particles was improved after modification. Observation by field emission scanning electron microscopy showed that the modified nano-Ag/TiO2 penetrated into the wood tracheids and formed a tight flocculent structure. X-ray diffractive analysis confirmed that modification did not affect the anatase diffraction pattern of nano-Ag/TiO2 or its photocatalytic and antimicrobial activities. Characterization by Fourier transform infrared spectroscopy showed that modified nano-Ag/TiO2 efficiently cross-linked with wood hydroxyl groups. This work provided a simple and effective method to develop a novel nano-Ag/TiO2 antimold agent for wood mold-proof treatment.Abstract
The mechanism underlying thermal degradation of oriented strand board was tested under a humid environment. Near-infrared reflectance (NIR) spectroscopy coupled with chemometric modeling was utilized to better understand the degradation of functional groups over time. The flexural properties, internal bond (IB), water absorption, and thickness swelling were tested after exposure to various times of 0, 3, 6, and 9 weeks in a climate-controlled laboratory to 76.7°C and 60 percent relative humidity. The largest reduction in all flexural and physical properties occurred during the first 3 weeks of exposure and then leveled off thereafter, while IB decreased significantly through the 9-week period (α = 0.05). Chemometric models built from NIR spectra revealed pertinent chemical changes in wood chemistry and resin components.Abstract
The Michigan furniture industry produces >150 tons/day of wood-based waste that can be upcycled into a wood–polymer composite (WPC). This study investigated the viability of using furniture waste as a feedstock for 3-D printer filament to produce furniture components. The process involves grinding and milling board scraps made of both LDF-MDF-LDF (where LDF is light-density fill and MDF is medium-density fill) and melamine-particleboard-paper impregnated with phenolic resins, premixing wood-based powder with the biopolymer polylactic acid, extruding twice through open source recyclebots to fabricate homogeneous 3-D printable WPC filament, and printing with open source fused filament fabrication–based 3-D printers. The results indicate that there is a significant opportunity for waste-based composite WPCs to be used as 3-D printing filament.Abstract