Abstract

The advent of tall wood structures in North America is heightening a public awareness that forest products, designed for higher and better uses, will lead to enhanced environmental benefits within the Circular Bioeconomy. The application of these newer wood-based processing technologies and their resulting products, in place of completive products such as concrete, steel and other non-wood construction materials, will redefine and expand the advantages that wood has as a construction material.

Further, the growing capability to use small logs, and diverse species, as raw material for the newer generation of forest products will magnify the carbon sequestration benefits from the working forest. A recipe of getting more benefits and improved utilization from the working forest is identified and described, while focusing on the means and methods of obtaining these benefits.

Abstract

Although pulping processes from wood are well-cemented technology, the emergence of bio-based nanotechnology, as well as the increase in concern about the environmental impact that these processes can have, calls for a reevaluation of the impacts that the traditional pulping methods have on the surfaces of the fibers and how variances will then affect the generation and properties of the nanocellulose materials, that will then impact the different applications that can be derived from them. Since literature tends to focus on one method and then characterize it, the aim of this review is to discuss the properties that have been reported of different fibers and nanofibers depending on the wood source, the chemical pulping method selected (kraft or sulfite methods), and the bleaching or lack of it and then compare the effects that these can have in properties such as crystallinity, chemical composition, surface charge, and functional groups present on the surface.

Abstract

A combination of youth out-migration and lack of in-migration have led to an aging workforce and population decline in Maine, whereas simultaneous declines in pulp and paper demand and biomass utilization have had negative impacts on the perceived future of the once-dominant forest products industry. These changes may increase uncertainty among employers as to the availability and training of the next generation of forest industry workers. This study reports our findings from an analysis of workforce supply and readiness in Maine's forest products industry. To estimate possible gaps in skills and work culture, we administered a survey to current forestry students and employers in the forest products industry. Skills were assessed in three domains: soft skills, knowledge skills, and technical skills. Our gap analysis focused on the difference between the stated importance of skills to employers and the current level of skill knowledge in the workforce across all three domains. Employers identified dealing with change, motivating personnel, negotiating contracts, problem solving, and financial analysis as the top educational needs. In addition, we assessed the willingness of students to accept the culture of work within the forest products industry. Despite the anecdotes shared by employers, we did not find significant evidence of a work culture mismatch between current students and their potential future employers. We recommend that gaps related to regulations, certification standards, or log scaling be addressed through workshops or on-the-job training, whereas areas such as customer relations, marketing, or problem solving could be emphasized in academic curriculum.

Abstract

Economic contributions of an industry sector are often vital information in the policy-making process. IMPLAN data and software were used to determine the economic contribution of forest industries to all 50 states plus Washington, D.C. Rankings of the states' contributions to employment, employee compensation, and value added were determined. National forest inventory data, rural population, and industrial energy costs were examined for correlation with total forestry contributions to each state's economies. Rankings were based on absolute contributions as well as contributions as a percentage of a state's total economy. Percentage rankings present the relative importance of forestry to a state's economy, and can differ considerably from absolute value rankings. Regional and national contributions were also calculated to model interstate and regional contribution “leakages,” or trade effects. Differences in both interstate and interregional trade flows are substantial. Industrial energy costs, rural population, and timber removals were significantly correlated with total economic contributions.

Abstract

Understanding the costs that residual habitat spaces carry into future rotations can provide managers more complete information when financially assessing timber management options that often extend for many decades. This case study assessed a streamside management zone's (SMZ) opportunity costs for a timber harvest site in north Louisiana. Timber removal occurred in summer 2018 by clearcut. A wooded buffer extending 50 feet on each side of a streambank and totaling 7.52 acres was retained; partial harvesting of pine timber was allowed. A timber inventory revealed that 99.6 tons per acre of standing hardwoods resided within the SMZ. Excluding noncommercial species placed its current present value (opportunity cost) at $1,803. Two future active management scenarios, “controlled” and “intensive,” were modeled over the next rotation at a 4 percent real discount rate, where price changes occurred at 0, 1, 2, 3, and 4 percent annually. Both management strategies consistently produced positive land expectation values (LEV) when SMZ opportunity costs were not included in the assessment. However, inclusion of SMZ protection under “controlled” management required timber price changes of 4 percent annually, while the “intensive” management option required timber price changes of at least 3 percent annually to return positive LEVs.

Abstract

Quarterly unit costs for a hypothetical logging firm were determined from the logging contract rate for Louisiana spanning the years 1992 to 2018. Machine rate methods were employed to disaggregate the contract rate into five cost centers: felling, skidding, loading, trucking, and tertiary (e.g., trucks, bulldozer, chainsaw). Risk was explained by the quarterly interest rate on a 30-year mortgage, and income taxes were estimated as a fixed percentage of gross income. The real logging contract rate averaged US$19.08 per ton (2018 constant dollars), and it has risen at an annual rate of 1.03 percent above that of inflation for roundwood. Trucking was the firm's highest cost activity followed by skidding, loading, felling, and tertiary. Rates of cost change followed the order of tertiary, trucking, loading, felling, and skidding. The firm faced financial hardship sporadically from 1992 through 2001, but profits were consistently returned from the second quarter of 2000 through the fourth quarter of 2006 (2000Q2 through 2006Q4). Since then, company earnings have fluctuated between profit (n = 25 quarters) and loss (n = 23 quarters). Losses were consistently generated from 2010Q4 through 2013Q2, and all of 2014, as well as in the final three quarters of 2018. Simulation of the contract rate and firm unit costs as stochastic processes utilizing a uniform distribution indicated a 0.48 probability of at least breaking even, but that increased to 0.69 when employing a normal distribution.

Abstract

Carbon sequestration is one of the tools being used to respond to climate change risks. It is known that carbon stored in wood products is a type of sequestration. However, time frames for evaluating wood use can affect conclusions about sequestration benefits; a long-term perspective and large spatial scale may help clarify these issues. Therefore, I undertook an equilibrium analysis of ongoing commercial forestry operations, relative to carbon sequestration, at the landscape scale. I found that for simple exponential decay functions for wood remaining in use over time, the total sequestered wood at equilibrium is simply the integral of the decay function multiplied by wood product produced. I show that this simple multiplier is a linear function of half-life. For a 50-year wood half-life, this equilibrium multiplier is 72.1. The half-life depends on the specific wood product (lumber, etc.). For waste wood used for energy at mills, typical values yielded a 100-year sequestration (avoided emissions) value of 12H where H is tons of carbon in logs delivered to the mill. This exercise demonstrates that commercial forestry is a significant provider of carbon sequestration through wood products, in addition to other sequestration benefits. The simple multipliers developed here are intuitive and can be easily used with operational wood product data at any scale.

Abstract

Himalayan forests act as reservoirs of carbon due to their high percentage of forest cover. The biomass values of these forests cluster around two different levels, which dwell between higher values (approximately 400 t/ha for Shorea robusta and Quercus leucotrichophora forests) and lower values (approximately 200 t/ha) for Pinus roxburghii forests. The present study is focused on assessment of variation in tree biomass and carbon sequestration at four sites dominated by chir pine (P. roxburghii Sarg.) forests located on two different slope aspects. We calculated the tree biomass following allometric equations based upon circumference at breast height by Chaturvedi and Singh (1982). The tree biomass values ranged between 97.87 ± 9.84 t/ha and 158.97 ± 9.39 t/ha; however, tree carbon values ranged between 46.48 ± 4.67 t/ha and 74.66 ± 7.17 t/ha across the study sites. Rates of carbon sequestration ranged between 0.2 ± 0.01 t/ha/yr and 3.96 ± 1.36 t/ha/yr. The rates were higher on slopes of northern aspect in comparison with southern aspect. The results emphasize that the biomass accumulation was higher in the trees located on northern aspects and can be better managed for developing a payment for ecosystem services strategy for following up of REDD+ in the country.

Abstract

The anatomical characteristics of culms in Bambusa pervariabilis bamboo at different ages and heights were investigated by microscopy and image analysis. Among the two vascular bundle types found in culms, the broken-waist type was considered typical, with the following measurements: average proportion of fibrous tissue, 41.53 percent; length, 1.75 mm; slenderness ratio, 117; and Runkel ratio, 4.00. These values were close to those of the moso bamboo (Phyllostachys edulis), which is commercially relevant in China. Age and height significantly influenced the anatomical characteristics of B. pervariabilis: with an increase in age, both the length and double-wall thickness of the fiber gradually increased, whereas its lumen diameter decreased. The width of vascular bundles and the length, width, double-wall thickness, and lumen diameter of fiber markedly decreased from the bottom to the top. Therefore, B. pervariabilis is an ideal raw material for pulping and papermaking, and its performance is close to that of moso bamboo.

Abstract

This study investigated the use of two nondestructive testing (NDT) methods to evaluate the mechanical properties of No. 2 grade: 2 by 8 and 2 by 10 southern pine lumber. The dynamic modulus of elasticity (dMOE) of each specimen was evaluated nondestructively by using longitudinal vibration and transverse vibration in edgewise and flatwise directions. After the NDT evaluation, the specimens were destructively tested and correlations between static bending MOE with modulus of rupture (MOR) and dMOE were developed. The overall MOE values were 11.14 and 10.96 GPa for 2 by 8 and 2 by 10, respectively. For MOR, the overall value for 2 by 8 was 42.59 MPa, and for 2 by 10 was 43.05 MPa. As expected, results showed statistically significant correlations between static MOE and dMOE (with r ranging from 0.87 to 0.96 for both sizes tested). Also as expected, weaker correlations were found between MOR and the dMOE values (with r ranging from 0.42 to 0.57 for both sizes tested). The lower correlations are largely explained by the difference between the NDT tools analyzing each specimen's global stiffness versus MOR, which is influenced heavily by localized characteristics. Perhaps this finding occurred because larger strength-reducing characteristics are permitted in larger section pieces (2 by 8 vs. 2 by 10) and thus they have opportunity for greater variability. The continuation of studies to develop more reliable NDT is crucial to improve the evaluation of mechanical properties of southern pine lumber and is beneficial to the southern pine timber industry.

Abstract

Tall wood buildings have become more prevalent in North America in the past 10 years. Tall wood-frame buildings implement both mass timber construction and products. Mass timber products are wood-based products that can withstand and hold large loads for long durations of time. Mass timber has allowed for large buildings, which consist mainly of wood, to be erected comprising multiple stories. One new mass timber product that has been fashioned is Mass Plywood Panels (MPP). MPP is a veneer-based engineered wood product, which is a massive, large-scale, structural composite lumber–based panel designed for use in building applications as both a vertical and horizontal element. For any new product to be used in the industry with confidence, a thorough investigation of its physical, mechanical, and connection properties is needed. A series of connection tests, such as fastener withdrawal resistance, dowel-bearing strength, lateral resistance, and a component test on a wall-to-floor system were conducted. The lateral resistance test indicated that the current European Yield Models can be used to calculate the yield loads and yield mode of the MPP by using the dowel-bearing strength of plywood. Three different connection configurations were tested in two distinct loading directions—shear and withdrawal. Their performances are evaluated and compared using two existing engineering models—namely, the American Society of Civil Engineers 41-13 tri-linear model and the seismic analysis of wood-frame structures 10-parameter connection model.

Abstract

A crosscut saw machine must be tuned to eliminate abnormal sawing marks or skewing during rapid wood processing. Once a wooden board is placed in the feed port, it is clamped and stabilized by a roller. However, the vibration amplification of the structure still causes the relative position of the blade to change and leads to the problem of saw marks on the wood surface. This article optimizes a saw machine by modal analysis based on the finite element method. The redesigned machine was compared to the original for natural frequency and mode shape. The analysis results revealed that at 31.43 Hz, stress reached the maximum value of 383.24 MPa on the frame of an alternating current motor. The mode shape showed significant deformation of the roller frame. By applying ribs on the chassis frame, vertical bending and torsion were reduced. The frequency of the sixth mode of the original machine was 43.9 Hz, which increased to 52.9 Hz after the redesign. The results showed that this was due to the addition of the ribs. A clamping roller was able to mitigate the vibration through the +y and z directions. The natural frequency of the modality was significantly improved through rib-enforced design. The structure of the improved design exhibited improvement compared to the original machine.

Abstract

The effect of moisture content on acoustic emission (AE) during wood damage was studied and the degree of damage was evaluated accordingly. In this article, the Pinus massoniana test-pieces of three different moisture content states, which are ovendried, air-dried, and water-saturated, were used to study the AE frequency characteristics of wood during bending failure. The original AE signal was subjected to wavelet denoising, and the denoised AE signal was classified into DAE (deformation AE) and FAE (fracture AE) according to the frequency distribution characteristics. Then, the instantaneous frequency of the AE signal was obtained by Hilbert transform, and the density of the two types of AE events was separately counted to evaluate the damage degree of the wood. The test results show that the AE signal in the process of wood damage and fracture was composed of two frequency components. The DAE signal frequency was concentrated at 30 to 60 kHz, the FAE signal was concentrated at 160 to 170 kHz, and the moisture content had no significant effect on the frequency distribution of AE events. In addition, the moisture content caused a change in the fracture toughness of the wood, so that the AE event density characteristics of the three damage processes were different. In particular, the ovendried test-piece showed obvious brittle fracture, and the AE event density level was slightly changed. Studies have shown that the change of AE event density based on instantaneous frequency can objectively evaluate and predict the degree of wood damage and fracture.

Abstract

Structural wall sheathing such as oriented strand board (OSB) and plywood have been heavily used in residential and commercial timber frame construction. The response of these wood-based composites under elevated temperatures between 100°C and 200°C (herein referred to as elevated temperatures) and exposure time needs to be characterized to assess residual strength of the materials in the existing structures. The main objective of this work is to study the effect of temperature and exposure time on shear strength and shear modulus of plywood and OSB. A total of 110 test specimens was tested in shear after exposure to five different temperatures and two exposure durations, followed by cooling to ambient temperature. The results indicated that the plywood and OSB behaved differently after exposure to elevated temperatures and exposure duration. Plywood showed a consistent degradation of shear strength with elevated temperature and time, while OSB did not exhibit a clear picture of thermal degradation. The results further indicated that the shear modulus of plywood and OSB remained unaffected after exposure to elevated temperatures.

Abstract

This study aimed to determine the effect of different wood flooring layer structures and surface features on water intake, shrinkage, and swelling rates under different relative humidity and water retention conditions. Nine wood flooring sample types were tested: solid wood beech (Fagus orientalis L.) flooring covered with polyurethane varnish, four engineered wood flooring types having different core-layers (solid-wood poplar (Populus nigra L.), 2× medium-density fiberboard, and plywood) covered with ultraviolet dried polyurethane varnish on beech veneer, and four laminated wood flooring types having different core layers (high-density fiberboard, medium-density fiberboard, particleboard, and plywood). The results showed the lowest water retention increase rates for 2 and 24 hours in the high-density fiberboard and medium-density fiberboard core-layered laminated wood floorings. The lowest thickness swelling rate occurred in the laminated wood flooring with a plywood core layer during exposure to high relative humidity, whereas the lowest swelling rate in the width dimension occurred for laminated wood flooring compared with other product types. The lowest thickness shrinkage rate was in the poplar core-layered engineered wood flooring, whereas the lowest shrinkage rate in the width direction was in the medium-density fiberboard core-layered engineered wood flooring and plywood core-layered laminated wood flooring at lower relative humidities. In conclusion, high-density fiberboard and medium-density fiberboard core-layered laminated wood floorings are advisable for flooring exposed to a humid environment. All laminated wood flooring types provided good resistance to swelling. The plywood core-layered laminated wood floorings, poplar, and medium-density fiberboard core-layered engineered wood flooring types performed the best for low-humidity environments.

Abstract

Lignin bioproducts derived from pulping of woody biomass find utility in multiple industrial applications. Ammonium lignosulfonates have historically displayed unique polymerization characteristics relative to other lignin materials and show promise as sustainable adhesives for the panel industry. To further understand the system's chemistry, polymerization reactions were observed through the lens of viscosity build-up using high temperature rheological measurements. It was found that highly controllable lignosulfonate properties like cooking temperature, pH, and percentage dissolved solids each significantly contribute to gelation behavior. The concept of thermal priming to shorten gelation time was also introduced and demonstrated. Finally, possible applications for this technology are postulated.

Abstract

Partial substitution of polymeric methylene diphenyl diisocyanate resin with soy flour increases the cold tack of the resin to the level achieved by urea formaldehyde resin. The tack can be fine-tuned by adjusting the amount of soy flour added. The increase in tack is caused by the reaction of the isocyanate resin with the water contained in soy flour, as well as with hydroxyl and other groups present in soy flour components. The higher cold tack should increase the stability of pre-press mats, especially in particleboard manufacturing.