Douglas-fir Lumber Research Articles

Determinants of Softwood Lumber Prices in the US Northwest

Abstract Lumber prices can be volatile and hard to predict from month to month yet are important for many sectors of the economy, ranging from forestry and construction. An economic model of lumber prices was developed and applied to data representing multiple supply and demand determinants of lumber. Using a suite of econometric models, monthly lumber prices were related back to variables including construction permits, US reserve bank credit, tariffs with Canada, exchange rates with Canada, and variables representing shocks associated with the COVID-19 pandemic. Preferred models use relatively small amounts of publicly available information, making them more accessible to industry participants who want to make their own price predictions. Such information can help guide decisions about whether to expand or scale back an operation in preparation for likely future price movements.

Aboveground Field Performance of Douglas-Fir Heartwood Subjected to Combinations of Glycerol, Boron, and Thermal Modification

Abstract The effect of pretreatment with either boron or glycerol followed by thermal modification on the durability of Douglas-fir heartwood was evaluated in an American Wood Protection Association ground proximity test in Hilo, Hawaii. Non–thermally modified samples were generally more heavily decayed than any of the modified woods, but there was no consistent effect of different thermal modification conditions on decay resistance. Thermally modified woods tended to perform better than untreated timbers but not as well as copper azole–treated Douglas-fir heartwood lumber in test at the same site. The results are discussed in relation to how the extreme site conditions might have made it difficult for thermally modified materials to perform.

Hygrothermal characterization and modeling of cross-laminated timber in the building envelope

Cross-laminated timber (CLT) is a type of mass timber panel used in floor, wall, and roof assemblies. An important consideration in design and construction of timber buildings is moisture durability. This study characterized the hygrothermal performance of CLT panels with laboratory measurements at multiple scales, field measurements, and modeling. The CLT panels consisted of five layers, four with spruce-pine-fir lumber and one with Douglas-fir lumber. Laboratory characterization involved measurements on small specimens that included material from only one or two layers and large specimens that included all five layers of the CLT panel. Water absorption was measured with panel specimens partially immersed in water, and a new method was developed where panels were exposed to ponded water on the top surface. This configuration gave a higher rate of water uptake than the partial immersion test. The rate of drying was much slower when the wetted surface was covered with an impermeable membrane. Measured hygrothermal properties were implemented in a one-dimensional transient hygrothermal model. Simulation of water uptake indicated that vapor diffusion had a significant contribution in parallel with liquid transport. A simple approximation for liquid transport coefficients, with identical coefficients for suction and redistribution, was adequate for simulating panel-scale wetting and drying. Finally, hygrothermal simulation of a CLT roof assembly that had been monitored in a companion field study showed agreement in most cases within the sensor uncertainty. Although the hygrothermal properties are particular to the wood species and CLT panels investigated here, the modeling approach is broadly applicable.

Evaluation of Lumber from Deconstructed Portland Residential Buildings

Portland, Oregon was the first U.S. city to implement a deconstruction ordinance in 2016. Although salvaged lumber from deconstructed dwellings can have high demand, the market for small-sized lumber is near saturation. New applications for this material are required for market development, industry diversification and the possible expansion of the deconstruction ordinance. Its use in mass timber is an option, but presently no wood property information exists for lumber from deconstructed dwellings inhibiting its use for structural purposes. Density and dynamic MOE (E) of 265, 38 mm x 89 mm (2 x 4) pieces of salvaged Douglas fir (Pseudotsuga menziesii) lumber were determined using a Metriguard Model 340 E-Computer. Additional data collected included sample dimensions, weight, and visual appearance. Over 50% of samples had a calculated stiffness comparable to the highest structural design grade for Coastal Douglas fir lumber. The presence of knots and damage, present in 66% and 59% of boards respectively, would likely downgrade boards, despite acceptable stiffness. Results show that 96% of samples were sufficiently stiff to meet minimum requirements for the manufacture of E3 grade cross laminated timber (CLT) panels and considering defects, this material is suitable for manufacturing CLT. Provision of wood property information for salvaged lumber is critical for market expansion and this work represents the first characterization of lumber from deconstructed Portland, OR dwellings.

Prediction of Douglas-Fir Lumber Properties: Comparison between a Benchtop Near-Infrared Spectrometer and Hyperspectral Imaging System

Near-infrared (NIR) spectroscopy and NIR hyperspectral imaging (NIR-HSI) were compared for the rapid estimation of physical and mechanical properties of No. 2 visual grade 2 × 4 (38.1 mm by 88.9 mm) Douglas-fir structural lumber. In total, 390 lumber samples were acquired from four mills in North America and destructively tested through bending. From each piece of lumber, a 25-mm length block was cut to collect diffuse reflectance NIR spectra and hyperspectral images. Calibrations for the specific gravity (SG) of both the lumber (SGlumber) and 25-mm block (SGblock) and the lumber modulus of elasticity (MOE) and modulus of rupture (MOR) were created using partial least squares (PLS) regression and their performance checked with a prediction set. The strongest calibrations were based on NIR spectra; however, the NIR-HSI data provided stronger predictions for all properties. In terms of fit statistics, SGblock gave the best results, followed by SGlumber, MOE, and MOR. The NIR-HSI SGlumber, MOE, and MOR calibrations were used to predict these properties for each pixel across the transverse surface of the scanned samples, allowing SG, MOE, and MOR variation within and among rings to be observed.

Impact of Tree Growth Rate on the Mechanical Properties of Douglas Fir Lumber in Belgium

In the context of questioning the relevance of making Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) silviculture more dynamic in Wallonia, we evaluated the influence of growth rate on the potential of Douglas-fir lumber for structural uses. Therefore, six trees 120 to 180 cm in circumference at 1.5 m were felled in 11 stands whose age varied from 40 to 69 years (mean circumference of the trees ≈150 cm; initial planting density from ≈2200 to 4400 seedlings/ha). In total, 706 boards (38 × 100 mm² and 70 × 180 mm² in cross section) were cut from these trees, whose average ring width ranged between 3 and 7 mm. The density of the wood (ρ) always appeared compatible with the mechanical class C30, regardless of the growth rate of the trees from which the lumber originated. The modulus of elasticity (E) and the modulus of rupture (fm) displayed by the 38 × 100 mm² boards cut from corewood were respectively 30% and 41% lower than those observed in outerwood. The latter did not seem affected by growth rate: E and fm characteristic values remained compatible with structural use, regardless of the mean ring width. Growth rate considerably affects the characteristic values of these mechanical properties when boards are made from corewood. Juvenile growth should therefore be limited.

Revisiting the Compression Parallel to Grain Design Values of Douglas-Fir

Abstract After the decrease in southern pine (Pinus spp.) design values, concerns were raised over the design values of Douglas-fir (Pseudotsuga menziesii), the most important structural species in the Pacific Northwest of the United States. Moreover, species need to be re-evaluated every 5 years for properties by the grading agencies. Variability within Douglas-fir lumber may have increased over time because of changes in the silvicultural practices and management techniques including the shift from government to private plantation. The compression parallel to the grain design values took the greatest hit for southern pine. To assess if there is any decrease in the compressional design values, No.2 grade Douglas-fir, of dimensions 38 by 89 by 2,438 mm, were attained from 36 different locations and were cut into 229-mm sections with 20 samples from each location. A total of 720 samples were tested to failure in compression parallel to grain according to ASTM International D4761. Additionally, 288 clear specimens were also tested. The compression strength was calculated and was compared among locations. The data were pooled to calculate the design values for compression parallel to the grain and compared with listed values in the National Design Specification. Variation of compressive strength within locations was observed, but even after accounting for the variation the calculated values are above the average reported value for clear wood specimens and higher than the code-recommended design value for nonclear specimens.

Evaluation of Maximum Strength and Modulus of Elasticity of Douglas-Fir Lumber in Axial to Grain Tension by Two Nondestructive Techniques

Modulus of elasticity (MOE) of Douglas-fir ( Pseudotsuga menziesii) lumber loaded in parallel to grain tension was evaluated by nondestructive techniques (transverse vibration and longitudinal stress wave) and the results were correlated to the actual properties. Nondestructive parameters of specific gravity, wave frequency and attenuation and wave speed were measured. Destructive tests were performed with the use of static tension and bending techniques. Regression analyses were performed to correlate all nondestructive and destructive techniques. Results showed the MOE in static bending can be predicted with good efficiency. The correlation coefficients (R) for this test ranged from 0.818 to 0.941. The maximum tensile strength presented a poor correlation to the nondestructive parameters with the highest R=0.582.

Effect of post-treatment processing on copper migration from Douglas-fir lumber treated with ammoniacal copper zinc arsenate

Migration of heavy metals into aquatic environments has become a concern in some regions of the world. Many wood preservatives are copper based systems that have the potential to migrate from the wood and into the surrounding environment. Some wood treaters have developed “best management practices” (BMPs) that are designed to reduce the risk of migration, but there are few comparative studies assessing the efficacy of these processes. The potential for using various heating combinations to limit copper migration was assessed using ammoniacal coper zinc arsenate treated Douglas-fir lumber. Kiln drying and air drying both proved to be the most effective methods for limiting copper migration, while post-treatment steaming or hot water immersion produced more variable results. The results should provide guidance for improving the BMP processes.

Stiffness of Douglas-fir lumber: effects of wood properties and genetics

Because stiffness (modulus of elasticity (MOE)) is important for structural wood products, breeders and silviculturists seek to efficiently measure and improve this trait. We studied MOE in a 25-year-old progeny test of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) using field-based tools (ST300 and HM200) to measure stress wave MOE of standing trees and logs. We measured density, static bending MOE, and transverse vibration MOE on 2 × 4s, and density, SilviScan MOE, and SilviScan microfibril angle on small clearwood samples. Bending MOE had moderate to strong phenotypic and genetic correlations with stress wave MOE of trees and logs, transverse vibration MOE of 2 × 4s, and the densities of 2 × 4s and basal wood discs but was weakly correlated with the numbers and sizes of knots. The best lumber grade had the highest bending stiffness and smallest edge knots. Bending stiffness had a strong positive correlation with the density of small clearwood samples and a moderate negative correlation with microfibril angle. Compared with microfibril angle and edge knots, path analyses indicated that density had the strongest direct effect on bending MOE. We recommend that breeders measure and select for stress wave velocity to improve bending stiffness in Douglas-fir. Genetic gains can be increased by including wood density, but genetic selection for fewer or smaller knots will be ineffective.

Effect of Armillaria root disease on quality and value of green Douglas-fir lumber

For a few tree species, scattered accounts of impact caused by root disease exist in the literature mainly at the tree level. No product quality impacts have ever been measured or properly costed. To provide some information on value impacts, green rough-sawn Douglas-fir lumber was cut from trees with and without Armillaria root disease. This produced 80 boards from six trees in two planted stands. Fewer boards came from living diseased trees compared to healthy trees of similar diameter (1.3 m) at both sites, suggesting that disease may affect stem taper or form. Lumber from diseased trees was affected most often by warp and for healthy trees by knots, but warp affected value the most. Disease appears to have at best no effect, and at worst, a negative effect on lumber value but is not likely to increase value. This is the first report of the impact of a root disease on lumber quality and value, but further work would be required to properly assess this. Key words: disease, Armillaria root disease, conifer, Douglas-fir, wood quality, lumber warping, lumber value, lumber grading

Effects of Bear Damage on Douglas-Fir Lumber Recovery

Abstract Bear activity resulting in injury to Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) trees has been documented as early as the mid-1850s in the Pacific Northwest. The study reported in this article was designed to help managers decide whether the common practice of removing the damaged but potentially valuable butt section of the bottom log and leaving it in the woods is warranted. Thirty-four damaged and 28 undamaged trees were selected from three sites in western Washington where bear damage has been a persistent problem. Trees were felled and bucked into 16-ft lengths. The damaged trees in the sample had been injured at ages between 10 and 15 years at two sites and between 10 and 65 years at the third site. The primary scaling deductions were for ring and scar defects. The 16-ft butt logs from the damaged and undamaged trees were sawn into dimension lumber. Bear-damaged logs were found to have lower cubic volume recovery than undamaged logs having the same small-end diameters. Lumber grade recovery was also influenced by bear damage; logs from damaged trees had a lower percentage of high-value lumber. The analysis suggests that the optimal harvesting policy is to haul the entire butt log to the mill rather than leaving the damaged portion in the woods. Although the value of the damaged portion is lower, most of the lumber recovered from that section can be used, with only a modest reduction in grade and value.

Preservative treatment of Douglas-fir lumber by the passive impregnation method with copper azole

Laser incised dry (mc=18%) and green (mc=33%) Douglas-fir was treated by the passive impregnation method of wood preservation having two different incising densities (7500 and 10000 holes/m2) and dipping times (3 and 12 hours). A 0.68% active ingredient solution of Copper Azole Type B (Tanalith CY) preservative was used in this study. The preservative retention and penetrated area were measured. The total preservative retention varied from 1.61 to 2.68 kg/m3 depending on the moisture content of wood and conditions of preservation, and in all cases it surpassed the minimum retention requirement for above ground use. The maximum penetrated area for dry lumber (mc=18%) was 96 and 88% across and along the grain, respectively. For green lumber (mc=33%), it was 90 and 85% across and along the grain, respectively.

Forest of Time: A Century of Science at Wind River Experimental Forest by Margaret Herring, Sarah Greene

over dams and fish runs, but the history is fairlythinand he glosses over the most difficult questions, such as the role of theEndangered Species Act requirements or near defiance of court rulings by successive federal adminis trations.Barenti findsmore information and insight inhis recorded discussions with people he encounters on his journey. In short,Barenti's journalistic approach ? he is a professional journalist ? provides most of the substance he includes on the salmon crisis in thePacific Northwest. He is unconvinced by anyone he meets, leaving readerswondering ifany posi tion on the salmon issue is salient. "A former girlfriendwho had spent her careerworking for various public advocacy groups," Barenti writes, "once called me a consensus seeker. Itwasn't a compliment_I lack the convic tions of a truebeliever. I am, instead skeptical about almost everything.Maybe working as a reporter has made me thisway; maybe my skepticismmade me a reporter" (p. 143).His skepticism may bewell placed, but itrendershis account fairlyshallow. For deeper treatmentof the issue by another journalist, readers should consult thedated, but still insightful, Common Fate: Endangered Salmon and thePeople of the Northwest (1995) by JosephCone. Barenti's book excels in adventure travel and environmental description, itsprimary contributions to literature on the Pacific Northwest. He beautifully delivers an intimate portrait, from the water's edge, of Idaho's wil derness, thedammed Lower Snake River, and theColumbia Rivermain stem that transports readers to realplaces and genuine engagement with the environment. He describes river conditions and the origins of changes that contribute to thedecline of anadromous fish, such as the South Fork of the Salmon River, where fishers regularly caught thousands of migrating Chinook until the 1960s,when "the forest service allowed timber cutting in the watershed [where] ... silt from the cleared mountainsides smothered clean gravelswhere salmon had spawned and filledpools where the young salmon lived before migrating to the ocean" (p. 67). On the lowerColumbia, where industrialism and urban growthmight seem to eliminate natural conditions, Barenti finds a riverscape that contradicts the image of an altered river."The riverbroke into amaze of channels braided throughwith islands big and small as itbroadened itselfinto an estuary.... theColumbia in its lastmiles looksmore like a patch of Pacific Ocean squeezed inland than a part of some great riversystemflowing down from high mountains in the continent's far interior" (p. 216). Mike Barenti takes themeasure of the Salmon, Snake, and Columbia riversby kayak and gives readers an up-close portraitof today's riverconditions.Mike Farmer carries us along his western road trip, providing snapshot images of today's changing American West. Both end abruptly,as domost travelnarratives, with clear affirmationsof the journeys'worth and benefits to the travelers.Like other travel ogues about the West, these two takeus to the territories, while theyalso offersmartportraits of a dynamically changing region. William L. Lang Portland State University FOREST OF TIME:A CENTURY OF SCIENCEAT WIND RIVER EXPERIMENTAL FOREST byMargaret Herring and Sarah Greene foreword by William G. Robbins Oregon State University Press, Corvallis, 2007. Photographs, maps, notes, index. 200 pages. $22.95 paper. Forests, perhaps more than any other type of ecosystem, invite long-term biological study. Because the ecosystems are dominated by spe cies thatare both long-lived and economically important, interest in better understanding both forestbiology and forestryprinciples is 486 OHQ vol. 109, no. 3 understandable. European and Asian forests have longbeen sitesof scientific investigation, and in recent centuries,American forestshave become so aswell. Situated along a tributary of theColumbia River in Skamania County, Washington, theWind River Experimental Forest has been a site for scientificactivity for a century.Research at the sitebegan very early in the twentieth century, with thefirst small scale foraysintounderstanding thephysiology and the ecology of theDouglas Fir forest.As Douglas Fir lumber increased in importance to the region's economy, so too increased the intensity of researchat the Wind River site.The United States Forest Service gradually formal ized the Wind River forest's role, eventually designating itan Experimental Forestwithin theboundaries of theGiffordPinchotNational Forest and putting itunder the control of the Portland-based Pacific Northwest Research Station. Forest of Time focuses on the scientific activitiesat the Wind River site, from itsearliest days up through itspresent-day role in federal forest research.Most of...

Comparative study between full cell and passive impregnation method of wood preservation for laser incised Douglas fir lumber

In this study, the ability of passive impregnation of Douglas fir (Pseudotsuga menziesii Franco) lumber was compared with a conventional full cell method. With an incising density of 10,000 holes/m2 carried out by CO2 laser, square Douglas fir lumber was treated by both passive impregnation and full cell method for 6 h and 50 min. Different incising densities were also used in passive impregnation to examine the optimum incising density. It was observed that there was no significant difference between these two methods regarding absorption of liquid, moisture content after dipping and penetrated area both at cross and longitudinal sections. However, the value was higher in case of full cell method. Regarding different incising densities, absorption and penetration of liquid was similar for 10,000 and 7,500 holes/m2 but it was low for 5,000 holes/m2. Therefore, it can be concluded that an incising density of 7,500 holes/m2 is the optimum for passive impregnation. The absorption of liquid and its distribution in wood indicates that this non-pressure passive impregnation method can be a good preservation method for impermeable lumber and can be an alternative to full cell method.

Analyzing the Distribution of Moisture Content in Kiln-dried Lumber Using Goodness of Fit Techniques – with Procedures

Knowledge of the distribution of moisture content in kiln-dried lumber is essential for quality control work. This paper describes formal methods and procedures for determining the distribution of moisture content in kiln-dried lumber using goodness-of-fit analysis, for three known distributions: Normal, Lognormal, and Weibull. Two graphical methods are employed: investigation of symmetry, and probability plotting. Formal mathematical tests are carried out for each distribution using test statistics based on the empirical distribution function (ECDF). The methods are tested on Douglas-Fir (Pseudotsuga menziesii) lumber collected from a production facility in British Columbia, Canada. Test results show that moisture content of kilndried lumber is well modeled by the threeparameter Lognormal distribution. In order to properly test the distribution of moisture content, all three parameters of the Lognormal distribution need to be considered: 'scale', 'shape' and 'threshold'. For kiln-dried lumber, the left bound (or threshold) of the distribution is greater than zero percent, and slightly smaller than the minimum lumber MC.

Short-term cyclic performance of metal-plate-connected wood truss joints

The objective of this research was to evaluate the performance of metal-plate-connected truss joints subjected to cyclic loading conditions that simulated seismic events in the lives of the joints. We also investigated the duration of load factor for these joints. We tested tension splice joints and heel joints from a standard 9.2-m Fink truss constructed from 38- ◊ 89-mm Douglas-fir lumber: 10 tension splice joints for static condition and for each of 6 cyclic loading conditions (70 joints total) and 10 heel joints for static condition and for each of 3 cyclic loading conditions (40 joints total). We evaluated results by comparing the strengths of the control group (static) with those of the cyclic loading groups. None of the cyclic loading conditions showed any strength degradation; however, there was significant stiffness degradation for both types of joint. The results of this research show that the current duration of load factor of 1.6 for earthquake loading is adequate for these joints.

Influence of species proportion and timing of establishment on stem quality in mixed red alder – Douglas-fir plantations

The relationships among stand structure, Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) branch characteristics, and red alder (Alnus rubra (Bong.)) stem form attributes were explored for 10- to 15-year-old trees growing in mixed Douglas-fir – red alder plantations. Treatments included a range of species proportions, and red alder was either planted simultaneously with Douglas-fir or after 5 years. Both replacement effects (total stand density held constant) and additive effects (stand density doubled) of competition were considered. When the two species were planted simultaneously and red alder proportion was low, red alder trees had low crown bases and much stem defect (lean, sweep, and multiple stems). Douglas-fir grew slowly when the two species were planted simultaneously. When red alder planting was delayed, species proportion did not affect red alder stem form, and height to the base of the Douglas-fir live crown decreased with increasing red alder proportion. Doubling Douglas-fir density increased the height to the base of the Douglas-fir live crown; however, doubling stand density by adding red alder did not affect Douglas-fir crown height. Douglas-fir lumber coming from mixed stands may be inferior because of the changes in knot characteristics associated with these different patterns of crown recession. In stands with a low proportion of red alder, red alder product recovery may be compromised because of the stem defects described above.

Fungal Colonization of Douglas-Fir Sapwood Lumber

The fungi colonizing Pseudotsuga menziesii (Douglas-fir) sapwood lumber were assessed in sam- ples collected from locations in western Oregon. A total of 547 isolates representing 29 genera and 45 species were obtained from sample boards. Graphium spp. represented 17% of all isolates, and the inci- dence of these species increased with time after saw- ing. The addition of streptomycin to malt extract agar improved isolation frequencies, while the addi- tion of cycloheximide sharply limited isolations to Graphium spp. and some Trichoderma isolates. The results indicate that Douglas-fir sapwood is suscepti- ble to colonization by a variety of fungal species. As a result, control strategies that concentrate on one fungus may have limited success because of interfer-

Shear Strength of Solid-Sawn Douglas-Fir Beams

The objective of this study was to improve current shear design criteria by establishing a test method for creating a database of beam shear strength of solid-sawn Douglas-fir lumber and correlating it to shear block test results; verifying whether the beam-size equation is a valid correlation between shear strength and beam size for solid-sawn material; and determining whether shear strength is more dependent on shear area, volume, or depth for modeling purposes. Experimental results are presented for 160 shear strength tests on unsplit, green, sawn No. 2 or better Douglas-fir lumber. Five different size specimens, ranging from 38 by 89 mm (2 by 4 in.) to 38 by 337 mm (4 by 14 in.), were tested in five-point beam shear. ASTM D143 shear block minors were cut and tested from each beam. Results adjusted to 12% moisture content were compared with prior research on southern pine and Douglas-fir glued-laminated timber beams. Statistical methods of censored statistics and regression investigated the following possible correlations: shear strength to beam size and beam shear strength to ASTM shear block strength. Results indicate that (1) a five-point test setup can consistently produce beam shear failures over a wide range of beam sizes; (2) shear strength is dependent on beam shear area; and (3) beam shear strength is related to ASTM D143 shear block strength values provided the reentrant corner stress-concentration effects are considered.