Large-diameter Logs Research Articles

Effect of low vacuum medium temperature drying on reduction of residual stress and correction of warp of Japanese cedar timber

Cryptomeria japonica (Japanese cedar) in Japan plantations are aging, and the main supply of timber in the market is shifting from small- and medium-diameter to large-diameter logs. The effective utilization of these logs has become an important issue in the timber industry. When producing timber-without-pith from large-diameter logs, an unavoidable warp occurs because of the release of residual stress within the logs. Utilizing high-temperature drying with a load on these timbers has achieved significant drying effects, and the residual stress-induced warp was corrected. However, high-temperature drying has drawbacks, such as high energy consumption and the potential for thermal degradation. We applied low-vacuum-medium-temperature drying (LVMT-drying, 10 days, 40 kPa, 80/55 °C (DB/WB)—90/65 °C (DB/WB)) with load (650 kgf/m2) to the stacked timber sawn from large-diameter logs to address these questions. When LVMT-drying was successful, residual stresses in timber-with-pith were reduced to nearly zero, and warps in timber-without-pith were reduced to less than 8 mm, i.e., below the Japan Agriculture Standard "Level 1" for 4000 mm timber, and the acceptance rate for "Level 1" increased from 45% (green timber) to 85% (treated timber) in the most successful sample. LVMT-drying is a practical drying method for timber from large-diameter logs because it is effective in reducing residual stress and correcting warps while shortening the treatment period and avoiding thermal degradation.

The sawmill yield increase potential with manufacturing increased wane and random width boards for engineered wood products

ABSTRACT The objective of this study was to assess the potential gains in log processing yield when integrating sawmill and engineered wood products manufacturing, a process which enables the use of random board widths and higher wane allowances than normal. The simulation was utilized and validated against real log sawing. The validation study showed that simulations consistently over-estimated the actual volume recovery by 2.1%. Simulation results showed that logs with smaller diameters returned higher recovery increases when adopting an increased wane strategy compared to large-diameter logs. When combining both increased wane and random width strategies, the recoveries were the highest. Using a weighted average of log classes (according to a common log size distribution in South African sawmills) an increased wane strategy returned higher recovery (11.0%) than a random width strategy (2.0%), but a combined strategy (13.0%) was the most efficient. The gains in volume recovery presented in this study showed that it is worthwhile to consider the integration of engineered products manufacturing in primary log processing using random widths strategy combined with higher wane allowance. For better use of the raw material, the maximum wane that engineered products can allow without compromising its strength and stiffness must be further investigated.

Морфологический анализ и оптимизация технологического процесса продольного раскроя круглых лесоматериалов

Coniferous sawn timber is extensively used in construction. However, the dimensional and qualitative composition of the round timber for lumber production has recently deteriorated significantly. The number of sawn logs with a diameter of 14–20 cm represents barely 50 % of the total supply of raw materials for sawmills. Besides that, large-diameter logs frequently have some signs of decay, which is mostly heartwood rot. Thus, the sawlog must be handled with caution. The problem is to intensify the sawing process, especially when logs have a presence of heartwood rot. This is possible to achieve with the implementation of modern technological sawing processes and specified equipment. A method of morphological research is used to select flowsheet diagrams of sawing and construction solutions for rip cutting equipment. The completeness of the morphological table is determined by the sum of all properties of the concept objects and is evaluated by obtaining effective technological and constructive solutions. According to the morphological method, a procedure of search systematization is developed. The patent search identified the main protective and published application documents concerning programs about ripping machines for round timber. The flowsheet diagrams for rip cutting of round timber and operational schemes for the equipment are adjusted according to the discovered regularities. A new sawing program is proposed in order to improve the efficiency of the equipment. It was licensed under a national patent of the Russian Federation. The evaluation of the possibility of implementing the technological process is made by analyzing the target costs for the production arrangement, the production rate per shift, and the quality of the final products. The proposed method for selecting directions to intensify the rip cutting of round timber gives the possibility to determine the effective technological and technical decisions at a project’s preliminary problem-solving stage. For citation: Toropov A.S., Byzov V.E. Morphological Analysis and Optimization of Technological Process for Rip Cutting of Round Timber. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 2, pp. 132–145. (In Russ.). https://doi.org/10.37482/0536-1036-2023-2-132-145

Effect of Sawing Variation on Hardwood Lumber Recovery—Part II: Board Count

Abstract Sawing variation (SV) describes all variations that exist in the production of lumber due to machine, material, set works, feed works, and cutting parameters. The necessary oversizing of board thickness due to SV diminishes sawmill profits and hence efforts must be made to reduce the variation. However, such efforts are costly and sawmill personnel generally do not know at which point efforts to reduce (SV) become more costly than oversizing the boards. In an accompanying paper we examined the impact of SV on lumber volume recovery and found that volume recovery increased comparatively more for thinner than for thicker kerfs and that the effect of reduced SV became more pronounced as diameter increased. In this second manuscript, the effect of SV on the quantity of boards sawn for a range of hardwood log diameters using the US Forest Service's LOg ReCovery Analysis Tool sawmill simulation software was researched and compared with the volume improvement from an earlier paper. Results showed that significant differences in the number of boards obtained was dependent on the log diameters sawn, the lumber target thickness, and the change (reduction) in SV. A minimal average recovery improvement of 3 percent due to reduced SV was observed across all kerf thicknesses, equating to a potential production value improvement of $336,000 for an 8 million board feet mill. All sawmills can benefit from reducing SV, but mills that saw large-diameter logs might consider pursuing SV reduction more aggressively than a sawmill sawing mostly small-diameter logs.

Wood-decay type and fungal guild dominance across a North American log transplant experiment

We incubated 196 large-diameter aspen ( Populus tremuloides ), birch ( Betula papyrifera ), and pine ( Pinus taeda ) logs on the FACE Wood Decomposition Experiment encompassing eight climatically-distinct forest sites in the United States. We sampled dead wood from these large-diameter logs after 2 to 6 y of decomposition and determined wood rot type as a continuous variable using the lignin loss/density loss ratio (L/D) and assessed wood-rotting fungal guilds using high-throughput amplicon sequencing (HTAS) of the ITS-2 marker. We found L/D values in line with a white rot dominance in all three tree species, with pine having lower L/D values than aspen and birch. Based on HTAS data, white rot fungi were the most abundant and diverse wood-rotting fungal guild, and soft rot fungi were more abundant and diverse than brown rot fungi in logs with low L/D values. For aspen and birch logs, decay type was related to the wood density at sampling. For the pine logs, decay type was associated with the balance between white and brown/soft rot fungi abundance and OTU richness. Our results demonstrate that decay type is governed by biotic and abiotic factors, which vary by tree species. • Wood-decay types and wood-rotting fungal guilds were measured in large-diameter decayed logs. • White-rot processes dominated among a wide-range of temperate forest sites. • Decay type was related to the wood decomposition rate for aspen and birch dead wood. • Decay type was associated with wood-rotting fungal guild balance in pine dead wood.

Microclimatic conditions mediate the effect of deadwood and forest characteristics on a threatened beetle species, Tragosoma depsarium

While climate change has increased the interest in the influence of microclimate on many organisms, species inhabiting deadwood have rarely been studied. Here, we explore how characteristics of forest stands and deadwood affect microclimate inside deadwood, and analyse how this affects wood-living organisms, exemplified by the red-listed beetle Tragosoma depsarium. Deadwood and forest variables explained much of the variation in temperature, but less of the variation in moisture within deadwood. Several variables known to influence habitat quality for deadwood-dependent species were found to correlate with microclimate. Standing deadwood and an open canopy generates warmer conditions in comparison to downed logs and a closed canopy, and shaded, downed and large-diameter wood have higher moisture and more stable daily temperatures than sun-exposed, standing, and small-diameter wood. T. depsarium occupancy and abundance increased with colder and more stable winter temperatures, and with higher spring temperatures. Consistently, the species occurred more frequently in deadwood items with characteristics associated with these conditions, i.e. downed large-diameter logs occurring in open conditions. Conclusively, microclimatic conditions were found to be important for a deadwood-dependent insect, and related to characteristics of both forest stands and deadwood items. Since microclimate is also affected by macroclimatic conditions, we expect species’ habitat requirements to vary locally and regionally, and to change due to climate warming. Although many saproxylic species preferring sun-exposed conditions would benefit from a warmer climate per se, changes in species interactions and land use may still result in negative net effects of climate warming.

Comprehensive study of distributions of residual stress and Young\u2019s modulus in large-diameter sugi (Cryptomeria japonica) log

Aged conifer forests in Japan are expected to produce large-diameter logs, defined as logs with a top-end diameter of 30 cm or more. However, the knowledge and techniques for industrial processing of large-diameter logs of Japanese wood species have not been sufficiently developed. This study was aimed at characterizing the longitudinal component of residual stress distribution of large-diameter logs of sugi (Japanese cedar, Cryptomeria japonica), a major tree species cultivated in Japan, as the processing yield of primary lumber from large-diameter logs is affected by the magnitude and distribution pattern of the residual stress. The radial distributions of the released strain of residual stress, tensile Young’s modulus, and residual stress were measured using 63 logs. The radial distributions of the released strain and residual stress showed typical patterns reported in previous studies: contraction near the bark and elongation near the pith in the released strain, tensile stress near the bark, and compressive stress near the pith. The radial distributions of Young’s modulus showed a typical pattern: low near the pith and high near the bark. The difference between the maximum and minimum released strains in each log varied widely among individuals, which was expected to result in a wide variation in crooking when rip sawing. The longitudinal uniformity and axial symmetry of the radial distribution of the released strain and residual stress were experimentally confirmed, which lays the groundwork for improved understanding of the residual stress in sugi logs.

Current status of plantation forestry in privately owned forests and efforts for effective use of large diameter logs

Current status of plantation forestry in privately owned forests and efforts for effective use of large diameter logs

Domestic large-diameter log use in the Japanese lumber manufacturing industry: focusing on regional differences

ABSTRACT Japan’s postwar policies with respect to forestry management have led to the aging of planted forests and a shift toward large-diameter logs that has created a challenge for how to use such logs in the lumber manufacturing industry. In recent years, medium-diameter logs have been the predominant type, and there has been less demand for large-diameter logs. This study examines the Japanese lumber manufacturing industry’s consumption of domestic timber using survey data from 21 member companies of the Domestic Timber Sawmill Association. The results suggest that regional characteristics and the tree species consumed are the two main factors that drive the decision to use large-diameter logs. While current demand for large-diameter logs is considered low, the results show that demand is present, and there are signs of growing consumption of these logs within the lumber manufacturing industry. As the current machinery that handles medium-diameter logs depreciates, it is expected that companies will respond by either introducing machinery that can accommodate large-diameter logs or changing their products.

Detection and Quantification of Coarse Woody Debris in Natural Forest Stands Using Airborne LiDAR

AbstractCoarse woody debris (CWD) is a meaningful contributor to forest carbon cycles, wildlife habitat, and biodiversity and can influence wildfire behavior. Using airborne laser scanning (ALS), we map CWD across a range of natural forest stand types in north-central British Columbia, Canada, providing forest managers with spatially detailed information on the presence and volume of ground-level woody biomass. We describe a novel methodology that isolates CWD returns from large diameter logs (>30cm) using a refined grounding algorithm, a mixture of height and pulse-based filters and linear pattern recognition, to transform ALS returns into measurable, vectorized shapes. We then assess the accuracy of CWD detection at the individual log level and predict CWD volume at the plot level. We detected 64% of CWD logs and 79% of CWD volume within our plots. Increased elevation of CWD significantly aided detection (P = 0.04), whereas advanced stages of decay hindered detection (P = 0.04). ALS-predicted CWD volume totals were compared against field-measured CWD and displayed a strong correlation (R = 0.81), allowing us to expand the methodology to map CWD over a larger region. The expanded CWD volume map compared ALS volume predictions between stands and suggests greater volume in stands with older and more heterogeneous stand structure.

A decision-support system to assist forest industry planning and investment when data are scarce: the case of hardwood veneering in subtropical eastern Australia

ABSTRACT An aspatial mathematical model has been developed to simultaneously support log processing investment decisions with respect to processing scale, facility location and log procurement when data are scarce. A key design principle was to make the model suitable for use by industry. The objective function maximises gross margins per hour of log processing time, and the model accounts for potential processing efficiencies with larger-diameter logs. To support log procurement decisions, the model estimates mill-delivered log costs at which a log procurement officer should be indifferent between purchasing alternative log types. The utility of the model is demonstrated with an application to rotary veneer processing of hardwood logs in subtropical eastern Australia. Complex interactions between processing scale, facility location and log procurement strategies were revealed by substantial differences in gross margins between modelled scenarios. Log procurement decisions were found to have the greatest potential impact on gross margins, followed by facility location and processing scale. The model highlighted that substantially higher returns can be earned from optimal log procurement strategies relative to approaches that either minimise log costs, maximise product recovery or do not differentiate between log types and simply utilise all available log volume.

Natural Drying and Chemical Characteristics of Hybrid Poplar Firewood Produced from Agricultural Bioenergy Buffers in Southern Québec, Canada

Implementing bioenergy buffers on farmland using fast-growing tree species could reduce firewood harvest pressure in woodlots and increase forest connectivity, while improving carbon sequestration, phytoremediation, stream habitats, soil stabilization and hydrological regulation. The objective of the study was to evaluate the natural drying and chemical characteristics of hybrid poplar firewood produced from bioenergy buffers, and to compare these characteristics with those of native species harvested in adjacent woodlots. In Trial A, 110 cm-long unsplit logs (a feedstock for biomass furnaces) were produced to evaluate the effect of log diameter class on firewood quality. In this trial, hybrid poplar firewood characteristics were also compared with Populus tremuloides, Acer rubrum and Fraxinus americana. In Trial B, the effect of hybrid poplar genotype and cover treatment was evaluated on the moisture content of short split logs (40 cm long). Firewood of satisfactory quality was produced on a yearly cycle for short split logs, and on a biannual cycle for long unsplit logs. Covering short split log cords with metal sheeting lowered the final moisture content (from 20.7% to 17.3%) and reduced its variability, while genotype did not significantly affect final moisture content. In Trial A, larger-diameter logs from hybrid poplar had lower element concentrations, but slightly higher moisture content after two years. A two-fold variation in N concentration was observed between diameter classes, suggesting that burning larger poplar logs would minimize atmospheric N pollution. Heating value, carbon and calcium concentrations increased following the seasoning of hybrid poplar firewood. After the first seasoning year outdoors, hybrid poplar had the highest moisture content (33.1%) compared to native species (24.1–29.5%). However, after the second seasoning year in an unheated warehouse, the opposite was observed (14.3% for hybrid poplar vs. 15.0–21.5% for native species). Heating value, carbon and nitrogen concentrations were similar between tree species, while high phosphorus and base cation concentrations characterized hybrid poplar, suggesting higher ash production. Poplar bioenergy buffers could provide a complementary source of firewood for heating in the fall and in the spring, when the heat demand is lower than during cold winter months.

Symposium on “Large diameter logs, be ambitious” in Hokkaido prefecture

Symposium on “Large diameter logs, be ambitious” in Hokkaido prefecture

Productivity of logging large diameter logs and long logs during final cutting in a mountain forest in Japan

ABSTRACTA large portion of planted forests in Japan have recently reached maturity. These trees have grown larger than previous stands, and are more difficult to log using current techniques. This study aimed to develop an improved logging system for logs with relatively larger diameters and lengths in Japan. In a moderate-slope mountain forest in Toyama Prefecture, we evaluated the productivity of final cutting and compared the productivity of each log length class (4 m, 6 m, and 8 m) using both current-sized and larger-sized machine harvesting systems. Moreover, different felling techniques for large diameter trees were assessed using a mechanical wedge that is commonly used in central Europe. We found that felling using the mechanical wedge had additional safety benefits. Furthermore, the productivity using the larger machine system was higher than those using the current techniques and systems; however, the productivity was only marginally higher for larger machines across log length classes.

Report on the lecture for development of high performance building materials to utilize large diameter logs

Report on the lecture for development of high performance building materials to utilize large diameter logs

Symposium on “Sunrise of utilization of large diameter logs”

Symposium on “Sunrise of utilization of large diameter logs”

Drying influence on the development of cracks in Eucalyptus logs

The aim of this study was to evaluate the effect of the moisture loss, diameter, and wood density on the appearance of surface cracks and end splits in Eucalyptus urophylla logs. The drying and emergence of defects were evaluated in 108 logs with diameters ranging from 60 mm to 150 mm from the initial moisture content to the equilibrium moisture content. The defects were measured during this time. Smaller diameter logs dried faster than larger diameter logs and took less time to reach the fiber saturation point. Surface cracks tended to develop during the loss of bound water. End splits developed during free water loss and continued to appear during bound water loss. Smaller diameters presented higher percentages of surface cracks compared with larger diameters, while larger diameters had a tendency for higher percentages of end splits compared with smaller diameters. The density did not influence the total emergence of end splits, but it did influence the total emergence of surface cracks, indicating a possibility for the selection of genetic material with lower tendency for cracking. Overall, the results reinforce the need to control drying at its beginning in order to decrease the risk of defects.

INTENSIVE MANAGEMENT FOR OPTIMIZING THE PRODUCTION OF HIGH-VALUE LOGS OF PINE FORESTS IN SOUTHERN BRAZIL

The best decision-making is a difficult task in forest management because it involves a large number of market and production variables. We simulated growth and yield of loblolly pine in high-quality sites, aiming to indicate thinning regimes and planting densities that maximize the production of large diameter logs (minor diameter >35 cm), as well as economically evaluating such regimes. We used the software OpTimber-LP for forest optimization problems. Simulations involved four planting densities (1,111; 1,600; 2,000; and 2,500 plants/ha); three thinnings with different weights, frequencies and ages of application; and clear cut at 25 years. Such combinations totalized in 2,916 simulated regimes. We calculated ANPV considering variations in interest rates, besides costs of production and returns resulting from thinnings and from clear cut. The findings indicated great productions of large diameter logs in regimes with low planting densities. Heavy thinnings (60% removal of trees) highlighted by being ideal to almost all thinnings, mainly in regimes with densities of 2,000 and 2,500 plants/ha. This intensity also was ideal to the first thinning, regardless the planting density. The most productive regimes presented large diameter log volumes ranging from 480 to 260 m³/ha, for regimes with 1,111 and 2,500 plants/ha, respectively. ANPV ranged from ~1.300 to ~2.100 R$/ha. As conclusion, less dense regimes provide largest productions in large diameter log, but lowest productions in total volume; as consequence, ANPV was larger in denser regimes, once the revenue obtained from high-value logs did not overcome that one obtained from finer (and consequently cheaper) logs. High-density regimes may produce less timber volume due to only one improper thinning, whereas low-density stands may have production really affected when are subjected to consecutive improper thinnings.

IMPORTÂNCIA DO MANEJO DE FLORESTAS NATIVAS PARA A RENDA DA PROPRIEDADE E ABASTECIMENTO DO MERCADO MADEIREIRO

A produção brasileira de madeira industrial baseia-se essencialmente nas plantações florestais, porém, somente no setor de serraria existe ainda uma parcela apreciável de toras de origem de florestas nativas, desconsiderando o uso da madeira para fins energéticos. Com a criação de concessões florestais deu-se um passo importante rumo ao manejo das florestas nativas do norte do país. Já no extremo sul existem florestas nativas somente em estágios de recuperação, em propriedades familiares e cujo manejo é muito restrito. No presente artigo argumenta-se sobre a importância de manejar as florestas nativas, mesmo em pequenas propriedades. Para isto, toma-se como exemplo o caso da Áustria, cujo território é dominado por florestas nativas em pequenas propriedades. A tradição deste uso é baseada em uma legislação adequada, no trabalho do serviço de extensão e de pesquisa que geram um ambiente no qual os benefícios materiais e imateriais da floresta se aliam aos interesses da sociedade e aos econômicos dos proprietários. O manejo das pequenas unidades florestais permite alcançar um regime de sustentabilidade periódico, cujas intervenções silviculturais partem das condições locais, sendo o objetivo central a árvore e não o povoamento. Este procedimento de manejo, atualmente recomendado para a produção de madeira de elevado valor econômico, é descrito de maneira resumida.

Strongman Log Push Press: The Effect Log Diameter has on Force-Time Characteristics.

Renals, L, Lake, J, Keogh, J, and Austin, K. Strongman log push press: The effect log diameter has on force-time characteristics. J Strength Cond Res 32(10): 2693-2700, 2018-Strongman training is becoming more common in strength and conditioning practices, particularly the log press. The existing literature analyzes force characteristics of the log clean and jerk or press compared with the weightlifting clean and jerk exercise. This investigation aims to explore the braking and propulsive phase performance characteristics of the push press with a barbell and strongman logs of different sizes. Ten experienced athletes volunteered to perform the push press exercise using 65% of their 1 repetition maximum using a small-diameter log, a large-diameter log, and a barbell. Analysis of variance showed a significant difference in all mean braking and propulsive characteristics (force, velocity, power, impulse, and displacement) between the barbell and both logs but there was no difference in lift duration. Comparison between both logs showed that the small log had significantly greater power (6%, p = 0.01), velocity (2%, p = 0.01), impulse (5%, p = 0.03), and force (3%, p = 0.01) but no difference in center of mass displacement or lift duration. In addition, propulsive phase when using the barbell was 4.4 times greater in force, 2.2 times in impulse, 1.8 times in velocity, and 2.3 times in power, and this was greater when compared with the larger diameter log. The athletes achieved larger propulsive outputs with a barbell over a log in the push press exercise in addition to showing a higher mechanical demand with a log that increases the larger log diameter, which may mean that the athlete needs to adapt loads when looking to optimize training parameters.