Wood and Fiber Science

Competitiveness and cost structure analysis of selected wood-processing industries in Ethiopia

Busha Teshome — 2026-01-16

Wood-processing industries contribute to economic and social development by producing a variety of wood products, yet limited information exists on their competitiveness and cost structures in Ethiopia. In this study we examined their competitiveness by using diamond model and cost structures of chipboard, plywood, and sawn wood industries using a survey of 29 large and medium firms and detailed cost analysis of three case studies. We used both qualitative and quantitative data to ensure a comprehensive analysis; quantitative data were examined using descriptive statistics including frequencies, means, and percentages to identify measurable patterns and trends, while qualitative data provided contextual depth and insights into the operational and strategic challenges faced by respondents. Findings revealed that limited support from government was a key constraint to competitiveness, while growing demand for wood products had a positive effect. Cost structures varied by industry type: raw materials were the largest expense for chipboard (43%) and plywood (51%) producers, while overhead costs dominated (76%) for the sawn wood (sawmill) respondent from 2019 to 2024. Profitability improved across all products: chipboard margins rose from 6.9% to 7.1%, plywood from 9.6% to 22.8%, and sawn woods from 3.8% to 13.3%. Enhancing the competitiveness of Ethiopia’s wood-processing sector requires addressing industry-specific challenges and costs.

Stem position and root infection influence heartwood formation in Douglas-fir plantations

Emmanuel A. Boakye — 2026-01-16

Heartwood formation influences timber quality and utilization, yet the factors driving its variation remain poorly understood. Understanding these variations can guide management strategies to influence heartwood development and enhance timber value through adapted silvicultural practices. This study examined the relationships between heartwood area and various tree characteristics in Douglas-fir plantations aged 25–34 years, across four sites within their native range in the southern interior of British Columbia, Canada. Stem analysis was used to quantify heartwood area and its relationships with tree-level variables, including sapwood area, tree height, root infection, and competition. To account for vertical variation along the stem, discs were categorized into three height classes based on relative stem height: lower (0–30%), middle (31%–60%), and upper (61%–100%). Heartwood area was primarily influenced by sapwood area, with the strongest effect at the middle stem, followed by the upper and lower positions. Tree height showed a position-dependent effect: positive in the lower stem and negative in the middle and upper sections. Root infection significantly increased heartwood area in the lower stem, with its effect weakening at higher positions. Competition had statistically significant but minimal effects, ranging from slightly negative in the lower stem to slightly positive in the upper stem. Our findings suggest that promoting sapwood development, particularly in the mid-stem, can enhance heartwood formation. While practices like thinning may contribute to this, the positive association between competition and heartwood in the middle stem indicates that maintaining moderate stand density may be more beneficial than aggressive spacing. Although root infection may locally stimulate heartwood near the base, its longer-term effects can disrupt the sapwood-heartwood balance and reduce tree vigor. Therefore, silvicultural strategies should aim to promote heartwood primarily through stand density management while limiting reliance on root stressors, integrating disease control measures to sustain overall tree health.

Estimation of Hankinson’s formula coefficient for elastic wave transmission velocity of red pine by the indirect method

HyeongJun Han — 2026-01-16

This study determined the Hankinson’s formula coefficient n for red pine (Pinus densiflora) using the indirect elastic wave transmission test under varying moisture contents (12%, 15%, and 18%). Hankinson’s formula is a mathematical relationship used to predict the mechanical properties of wood at any angle relative to the grain. With information on the elastic wave transmission speed parallel (P, 0°) and perpendicular (Q, 90°) to the fiber direction, the wave transmission speed at intermediate angles can be predicted using Hankinson’s formula. A visually defect-free 81- to 90-year red pine board (400 × 400 × 50 mm) was selected as the test specimen. The moisture content of specimens was adjusted to 12%, 15%, and 18%. Coefficient n of Hankinson’s formula, was calculated by taking measurements were taken at grain angles of 0°, 15°, 30°, 45°, 60°, 75°, and 90° using both ultrasonic and stress waves by the indirect transmission method.
The coefficients (n) obtained from ultrasonic wave measurements were 2.0, 1.9, and 1.9 at 12%, 15%, and 18% moisture contents, respectively. The values determined from stress wave measurements were 1.7, 1.7, and 1.6 at the same moisture contents, respectively. These results indicate that the transmission path of elastic waves in red pine can be effectively modeled using the coefficient n from Hankinson’s formula, which varies with moisture content. This suggests the potential applicability of the formula in evaluating internal defects or decay in wood through quantitative wave-based analysis.

Migration of polycyclic aromatic hydrocarbons from creosote-treated roundwood in soil under controlled laboratory conditions

Kaelin Quigley — 2026-01-16

Creosote is used as a wood preservative in a variety of terrestrial and aquatic environments, and some of its components can be detrimental to ecosystem function at high enough concentrations. Therefore, it is important to quantify chemical migration from creosote-treated commodities to better understand their impact. This work measures the migration of 16 polycyclic aromatic hydrocarbons (PAHs) from creosote-treated southern pine and Douglas-fir roundwood posts set in soil contact in barrels under controlled laboratory conditions. Experiments were carried out in soils with both low and high organic matter (OM) content. PAH content was measured in soil over a 32-month period at two distances from the post surface (76 and 152 mm) and at three different depths from the surface (0–15 cm, 15–30 cm, and 30–46 cm). PAH concentration varied widely among the 16 different compounds measured, but generally PAHs with four or fewer rings were more abundant and more frequently found than larger five-ringed PAHs across sample types. It was difficult to identify clear patterns in PAH migration by distance from wood and depth from soil surface because levels were generally low (below 0.4 PPM), and the data was highly variable, which eliminated the possibility of differentiating means statistically in most cases. In many cases, PAH levels found in controls that contained untreated wood were similar to levels found in control soil that contained treated wood, indicating some PAHs found could originate from the soil or surrounding environment. The clearest trend found was that high OM soils much more frequently contained measurable levels of the different PAHs, which is likely due to the known affinity PAHs have for OM. This work provides some methodological insight into studying PAH migration in soils that can help explain PAH migration patterns in soils with different proportions of OM. It also shows that without wetting with liquid water or other physical disturbances faced by wood in service, PAH migration from creosote-treated wood into soil is minimal.

Horizontal flame spread of flame-retardant-treated Japanese cedar (Cryptomeria japonica) exterior siding material

Eun-Suk Jang — 2026-01-16

The primary objective of this study was to determine whether in-house-developed flame-retardant-treated cedar could serve as an exterior material, not only by meeting the fire-resistance criteria of the cone calorimetry test, but also by demonstrating dependable performance under realistic fire conditions. The results of the cone calorimetry test indicated that the material met the established criteria for total heat release and peak heat release rate, validating its classification as a quasi-noncombustible material. Furthermore, the ASTM E84 Steiner tunnel test was conducted to evaluate the performance of the flame-retardant cedar siding under conditions that simulated real fire scenarios more closely. Flame propagation exhibited a delayed onset and progressed gradually from 2.5 ft to 5 ft over 10 min, indicating restrained flame spread. Concurrently, smoke development remained negligible throughout the test, which is critical for maintaining visibility and minimizing exposure to toxic combustion byproducts. Post-test examination revealed minimal structural degradation, with no evidence of cracking or penetration beyond superficial charring, suggesting that the material retained its physical integrity even under elevated thermal stress. Collectively, these findings confirm that the flame-retardant cedar siding meets the requirements for an ASTM E84 Class A rating and functions as a reliable exterior cladding material capable of enhancing occupant safety in fire scenarios.

Editorial: The New and Improved Wood and Fiber Science

Editorial — 2026-01-16