Large-diameter Logs Research Articles

Crown thinning on Eucalyptus dunnii stands for saw- and veneer logs in southern Brazil

Eucalypt plantations occupy > 5 million ha in the warm regions of Brazil. In the southern highlands, however, forestry is dominated by Pinus taeda. The frost-tolerant Eucalyptus dunnii Maiden seems to be suitable for that area, but there are few case studies and very little information about managing eucalypt stands for multiple uses. Thinning and pruning are key silvicultural management practices for E. dunnii plantations that produce saw- and veneer-logs. With this study it was aimed to evaluate the use of crown thinning to produce large-diameter trees in Eucalyptus dunnii stands. At age 2 years, 200 potential crop trees (pct) per ha were selected, pruned, and released from competition in five different intensities: no thinning, three practice-oriented variants, and one extreme and early thinning. Experimental data was collected until the stands were 13 years old. The production of large-diameter log assortments (≥ 40 cm) was positively associated with thinning and was strongly dependent on the site quality. Optimal results occurred with initial densities of 1000 trees ha−1 associated with early and relatively aggressive thinning. However, the final selection of pct’s and their release from competitors should not take place before dominant trees can be efficiently recognized (h100 = 15 m). Following these recommendations, at age of 13 years, the production of 100 m3 ha−1 of big sized timber (> 40 cm) can be expected.

The Detection of Structure in Wood by X-Ray CT Imaging Technique

Medical computed tomography (CT) has been used in forestry science and the wood industry to explore the internal structures of trees in a non-destructive way. The wood material has great diversity in structure, density, and size. The software system for medical CT is not applicable to analyze and process sectional images of wood. In order to solve this problem, a CT imaging system, based on the principle of X-ray fan-beam scanning, was constructed for this study. The computer tomography technique was applied in the non-destructive testing of wood. Four kinds of representative specimens—laminated wood, multi knot logs, large diameter logs, and small diameter logs—were selected as scanned objects. The sinusoidal images and sectional images were reconstructed with scanning data. The results showed that the accuracy of CT images is determined by the information in the sinusoidal images, from which the shapes and locations of cracks and knots can be identified. The internal properties of wood in some tomography, such as the size, number, and location of cracks and knots, the number of tree rings, and the growth law of early wood and late wood can be visually observed. Finally, the feasibility and validity of the CT imaging system was tested as a non-destructive method for verifying the internal structures of wood.

Symposium on “How to use large diameter logs”

Symposium on “How to use large diameter logs”

Moment Behavior of Laminated Beam-Column Joint with Glued-In Steel Rods Manufactured from Small-Diameter Larch Logs

Abstract To promote the structural use of small-diameter logs often harvested in Korea, the use of laminated members with square timber obtained from small-diameter logs as their elements is being considered. With the objective of improved strength, elements obtained from large-diameter logs were combined with elements obtained from small-diameter logs. In this study, the authors prepared beam-column joints using these laminated members and examined their moment resistance performance. To join a laminated beam and a laminated column, the authors used glued-in steel rods. The results of a mechanical test on the moment–deformation angle relationship showed that from the initial force to the failure point, the behavior was mostly linear. Moreover, the rotational stiffness was approximately 900 kNm/rad, the maximum moment was approximately 30 kNm, and the joint efficiency for deformation was approximately 0.8. It was revealed that a significant amount of the deformation in this specimen resulted from the bending deflection of the laminated column. The authors also estimated the rotational stiffness and maximum moment through linear analysis. The slip properties of the deformed bar, compression properties perpendicular to grain of the laminated column, and bending properties of the laminated column were taken into consideration. The estimated results were mostly consistent with the experimental results. As a method to easily understand the moment resistance performance of these joints, the present proposed estimation method should be effective.

Strength and Rigidity Performance of Laminated Members Using Small-Diameter Logs

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.

Deadwood Decay in a Burnt Mediterranean Pine Reforestation

Dead wood remaining after wildfires represents a biological legacy for forest regeneration, and its decay is both cause and consequence of a large set of ecological processes. However, the rate of wood decomposition after fires is still poorly understood, particularly for Mediterranean-type ecosystems. In this study, we analyzed deadwood decomposition following a wildfire in a Mediterranean pine plantation in the Sierra Nevada Natural and National Park (southeast Spain). Three plots were established over an elevational/species gradient spanning from 1477 to 2053 m above sea level, in which burnt logs of three species of pines were experimentally laid out and wood densities were estimated five times over ten years. The logs lost an overall 23% of their density, although this value ranged from an average 11% at the highest-elevation plot (dominated by Pinus sylvestris) to 32% at an intermediate elevation (with P. nigra). Contrary to studies in other climates, large-diameter logs decomposed faster than small-diameter logs. Our results provide one of the longest time series for wood decomposition in Mediterranean ecosystems and suggest that this process provides spatial variability in the post-fire ecosystem at the scale of stands due to variable speeds of decay. Common management practices such as salvage logging diminish burnt wood and influence the rich ecological processes related to its decay.

Effects of riparian buffer width on wood loading in headwater streams after repeated forest thinning

Forested riparian buffer zones are used in conjunction with upland forest management, in part, to provide for the recruitment for large wood to streams. Small headwater streams account for the majority of stream networks in many forested regions. Yet, our understanding of how riparian buffer width influences wood dynamics in headwater streams is relatively less developed compared to larger fish-bearing streams. The effects of riparian buffer width on instream wood loading after thinning can be difficult to discern due to the influence of basin characteristics and reach-scale geomorphology on wood recruitment, breakage and redistribution. We assessed the relationships between instream wood loading, geomorphology and riparian buffer width in small headwater streams after upland thinning. Then we examined the distances between pieces of stream wood and their sources, or the distance from which wood volumes were recruited to these streams. Data were collected along 34 stream reaches at six different sites in a replicated field experiment, comparing three no-harvest streamside buffer treatments (∼6-m, 15-mminimum, and ∼70-m widths). At each site, second-growth forests were thinned first to 200trees per ha [tph] and ∼10years later to 85tph, alongside an unthinned reference unit (∼400tph). We measured wood loading (m3/100m) four times: (1) prior to thinning; (2) year 5 post-1st thinning; (3) immediately prior to the 2nd thinning; and (4) year 1 post-2nd thinning. The majority of wood volume was in late stages of decay, most likely biological legacies from the previous forest stand, and distributed along the streambank. Surprisingly, wood volume in early stages of decay was higher in stream reaches with a narrow 6-m buffer than in stream reaches with larger 15- and 70-m buffers and the unthinned reference units. Additionally, wood volume increased with drainage basin area. Only 45% of wood in late stages of decay could be associated with a particular source. Yet, 82% and 85% of sourced wood in early and late stages of decay, respectively, originated from within 15m of streams. Expected continue low rates will likely result in declining volumes of wood in late stages of decay. Thinning and directional felling of logs into to streams could be used to augment wood volumes in the near term, and accelerate the development of large-diameter logs for future inputs. However, the relationship between instream wood loading and basin area suggests that instream wood loading depends on management across the entire watershed.

Using Small Diameter Logs for Cross-Laminated Timber Production

Sawing small diameter logs results in lower yield compared to sawing large diameter logs. This is due to geometry; fitting rectangular blocks inside an approximately cylindrical shape is more difficult for small than for large diameters. If small diameter logs were sawn in a way that follows the outer shape, yield would increase. The present study considers whether this can be done by sawing flitches into trapeze shapes. These can be glued together into rectangular products. Cross laminated timber (CLT) products are suitable for this. The study was based on 4,860 softwood logs that where scanned, and the scanning data was used for sawing simulation. The log top diameters ranged from 92 to 434 mm. The volume yield of CLT production using trapeze edging was compared to cant sawing of boards. The trapeze edging and CLT production process improved yield compared to cant sawing by 17.4 percent units, for logs of a top diameter smaller than 185 mm. For all logs, the yield decreased using the trapeze edging method. To conclude, a trapeze edging method shows promise in terms of increasing volume yield for small diameter logs, if boards can be properly taken care of in a CLT production process.

大径材から得られたスギ心去り平角材の曲げ性能

大径材から得られたスギ心去り平角材の曲げ性能

A review of heartwood properties of Tectona grandis trees from fast-growth plantations

Teak (Tectona grandis L. f) has been introduced to reforestation programs in many tropical countries for timber production. The use of teak plantations has changed the supply from large-diameter logs to small-diameter logs featuring a higher proportion of juvenile wood and more knots. Generally, the teak from fast-growth plantation is harvested after 15–30 years of growth, with logs ranging from 12 to 30 cm in diameter. The goal of this work was to review the factors that influence the heartwood formation, variation, quality, color, and durability in teak and to understand which factors should be controlled in fast-growth plantations. Important factors in the heartwood properties of teak trees from fast-growth plantations are as follows: the tree age, longitudinal variation, geographic location, environmental conditions, and silvicultural activities. These factors influence heartwood extractive content, color variation, and durability.

Determining the effect of storage conditions on the natural drying of radiata pine logs for energy use

BackgroundThe effect of storage duration and technique on the moisture content of radiata pine (Pinus radiata D. Don) biomass logs in New Zealand was studied.MethodsTwo trials were established in the South Island to represent favourable and unfavourable storage conditions, namely: summer storage in a warm and dry location and winter storage in a cold and relatively wet location. In total twenty stacks were installed, each consisting of approximately 600 kg of radiata pine logs (wet initial weight), with treatments intended to compare small diameter logs, large diameter logs, large diameter logs split, as well as the effect of cover. Moisture content was gravimetrically determined at the beginning and the end of the trials. All stacks were weighed at 1 to 4 week intervals to follow the weight loss trend over time.ResultsAfter 24 weeks in summer storage, the moisture content (wet basis) of radiata pine logs decreased from an initial value of 53% to between 33 and 21%. The decrease was greatest for uncovered small logs and decreased was smallest for covered large logs. Due to wet and cold weather conditions, logs stored in winter- dried very little over a 17-week period. Moisture content decreased from an initial value of 58% to between 51 and 49%, with no significant treatment differences observed in the winter trial.ConclusionsThe best summer storage technique was the simplest and consisted of stacking small logs without any cover. The larger logs dried the slowest, but splitting accelerated drying significantly. Covering did not help and results indicated that, while covering is useful for preventing rewetting of dry logs, it does not improve drying of wet logs.

Eucalypt growth in monoculture and silvopastoral systems with varied tree initial densities and spatial arrangements

Brazil has large stretches of degraded land, mainly occupied by pasture. Recently, the Brazilian government created a program providing financial support to recover these lands throughout the country by establishing agroforestry systems, among others. To select the most appropriate initial spatial arrangements and tree planting density for such systems, the plant growth and leaf area index (LAI) of a Eucalyptus camaldulensis clone were evaluated in five spatial arrangements: 3.6 × 2.5 m, and 3.3 × 3.3 m (monoculture), and (2 × 2) + 10 m, (3 × 3) + 9 m, and 9 × 3 m (silvopastoral systems), with 1,111, 918, 833, 556 and 370 plants per hectare, respectively. The arrangement did not affect plant height growth (p > 0.05) up to 50 months. The average diameter was affected by plant proximity in the planting line, being smaller (p 0.05) in volume per hectare, which was higher (p < 0.05) than for the other arrangements studied. LAI decreased with age and it was higher (p < 0.01) in the monoculture as compared to the silvopastoral systems. The silvopastoral system can be established in the (2 × 2) + 10 m arrangement for high biomass production besides having the additional benefit of financial returns from the pasture, as compared with the monoculture. The 9 × 3 m arrangement is preferable for large diameter log production.

Comparative analysis of on-farm timber conversion systems in Kenya

Exploitation of trees on private farms in Kenya is mainly by chain, bench and pit sawing systems, whose efficiency has not been well established. The sawing systems were evaluated for their performance using three species: Eucalyptus saligna, Grevillea robusta and Prosopis juliflora. Data was subjected to analysis of variance and mean comparisons. Results showed significant differences (P<0.05) among the sawing systems. Chainsaw system recovered more logs from the trees with a log recovery rate of 76%, which was significantly higher than those of 65 and 63% for bench and pit saws respectively. Timber recovery rates of 39.8, 35.9 and 30.0% for pit, bench and chain saws respectively were observed. The chainsaw system produced the highest rate of timber output (0.23 m3/man-hour), differing significantly from benchsaw (0.17) and pit saw (0.08). Chain and bench saws recorded significantly different fuel consumption rates of 8.41 and 14.86 m3l-1respectively. Timber sawn with the chain saw had the highest dimensional deviation (+/-5.53 mm), which was significantly higher than deviations for benchsaw (+/-3.55 mm) and pitsaw (+/-2.44 mm). The study shows that, although chainsaw recorded the highest timber production rate per man hour, it had the lowest timber recovery. Timber sawn with this system had the highest dimensional deviations. Bench saw was more economical for sawing large diameter logs, with chainsaw performing better for small diameter logs. The three systems recorded very low recovery of timber and are thus not suitable for processing timber, in this error of diminishing tree cover unless they are improved. Key words: Efficiency, sawing systems, timber recovery, production rate, size, deviation.

Sawing patterns for large-diameter sugi (Cryptomeria japonica D. Don) sawlogs: Current status and future outlook

A survey was conducted at nine sawmills in Japan to evaluate and compare the sawing of sugi (Cryptomeria japonica D. Don) logs of 30 cm and more in diameter. The purpose was fourfold: (1) to document sawing patterns appropriate to the large-diameter logs; (2) to examine the composition of wood components (structural, nonstructural, and fixtures) produced from those patterns; (3) to investigate log and product prices; and (4) to ascertain distances to the log supplier and product markets. Impetus for the study arose from a forecasted shift in the diameter distribution of plantation trees in Japan; from small and medium-sized logs to large-diameter logs. With an overabundance of large-diameter domestic logs forecasted within the next decade, the need to understand how to best utilize and effectively process the large-diameter resource is of utmost importance.

A Status and Development Direction of Lumbering Industry in Korea

The government defines eco–friendly lumbering industry as its essential challenge for fostering of forest business and raising of its competitiveness and aims at 17% of wood self–supply ratio in 2017 from 10% of it in 2005, as well as promotes stable supply system of wood, improvement of timer production and distribution system, industrial application of wood resources, supply expansion of lumbering industry, creditability of domestic materials, and development of processing technologies. However, the financial difficulty has been deteriorated because of economic slump and export limitation of countries with wood resources and therefore total output of lumbering industry was reduced by 7% to 2500 billion KRW in 2008 than that in 2007 and the number of general lumbering companies was also reduced by 10% from 674 in 2007 to 609 in 2008. Although researches on lumbering companies and wood industry include research on development measures of wood industry and analysis of environmental factors affecting wood supply, recently these researches are not active so much and there is few study on management cases for lumbering companies by regions. Thus in this study investigation in order to seek problems on management and future developmental direction was conducted against lumbering enterprises located in Gapyeong–gun and Pocheon–si that have larger areas of artificial forest with Korean white pine and larch compared with other regions in Gyeonggi Province. As a result, it was found that there were some factors making management of lumbering enterprises more difficult, including increase of items substituting wood, outworn lumbering facility, decrease of demand for lumbering product from economic slump as well as raise of wood price and labor costs. Therefore, it was identified that for enhancement of public beneficial function of forest through fostering of lumbering enterprises and expansion of domestic material consumption, and production of large diameter log with good quality, it was needed to prepare various support plans such as tax reduction and exemption and financial support for lumbering enterprise.

A lack of large-diameter logs and snags characterises dead wood patterns in Irish forests

Dead wood is an important component of forest ecosystems and volumes vary depending on forest age, management intensity and productivity. This is the first large-scale study to quantify dead wood in Irish forests and to compare them to forests in other locations. We measured the volume and size distribution of logs, the density and size distribution of snags and the volume of dead wood contained in stumps in Oak ( Quercus spp.) and Ash ( Fraxinus excelsior) forests and in Sitka spruce ( Picea sitchensis) plantations throughout Ireland. We also assigned each log, snag and stump to one of three decay classes (intact, part-rotted and well-rotted). We found no significant difference in log volume between any of the forest types. The majority (>90%) of logs were less than 20 cm in diameter, and large logs (>40 cm diameter) were scarce. We found a relatively high density of snags in all forest types but, as in the case of logs, over 90% of snags were <20 cm DBH and large snags (>40 cm DBH) were rare. The volume of dead wood contained in stumps was significantly higher in plantations than in Oak or Ash forests as a result of thinning and harvesting. Most logs and snags were moderately decayed but, in plantations, most stumps were intact. Log volume and the size of logs and snags were considerably lower than in old-growth forests in other regions. These patterns may reflect historical use of Irish forests for coppice and timber production. Management for biodiversity should aim to accelerate dead wood accumulation to increase the frequency of large-diameter logs and snags. Although management seeking to replicate the dead wood volumes of old-growth forests is ideal, it may be unrealistic in the short term.

Spatial distribution of dead wood and the occurrence of five saproxylic fungi in old-growth timberline spruce forests in northern Finland

Adequate understanding of the factors that determine the establishment and survival of dead-wood-dependent species in natural forests is a prerequisite to the successful maintenance of these species in managed forests. This study investigated the factors affecting the occurrence of five wood-inhabiting polypores in old-growth timberline spruce forests in northern Finland, including the substrate availability and the spatial arrangement of large-diameter logs. The volume of coarse woody debris (CWD) varied significantly between the sites (range 15–30 m3 ha−1), large-diameter logs comprising on average 35% of the total CWD volume. However, the within-site variation in CWD volume was 10–15 times larger than the between-site variation. The spatial distribution of large-diameter logs was aggregated or initially aggregated on four sites and random on one site, creating local patches of high CWD volume. An individual target species occurred on average on 8% of all large-diameter logs, and on 11% of optimal logs (as determined by the decay stage). The characteristics of the logs and stand variables explained partly the occurrence of the target species; furthermore, the mortality pattern of trees (stem breakage versus uprooting) and the presence of primary decomposers also significantly affected the occurrence of the target species. The results indicate that besides substrate availability and quality, local habitat factors and species interactions also play a role in the occurrence of wood-inhabiting fungi in boreal timberline forests.

Effects of sunlight exposure and log size on pine engraver (Coleoptera: Curculionidae) reproduction in ponderosa pine slash in Northern Arizona, U.S.A.

Abstract1 Abiotic conditions within logs can affect pine engraver Ips pini (Say) reproductive success, and slash management techniques have been developed that exploit these relationships to reduce brood production. In the present study, we investigated the affect of sunlight exposure on phloem temperature and moisture in logs of two diameters and the subsequent effects on pine engraver reproduction.2 Logs, 30 cm in length, with diameters of 10 and 15 cm, were cut, left in the field for natural colonization by I pini, and then placed in an open meadow and under shade cloth, providing 27% and 66% shade, until offspring beetles had left the logs. Phloem temperature and moisture were recorded over the duration of the experiment and, at the end of the field experiment, logs were dissected and galleries were measured to gauge beetle reproductive success.3 As sunlight exposure increased, phloem temperatures increased and potentially lethal temperatures were often reached in the high‐sunlight exposure but seldom in the low‐sunlight. Smaller diameter logs had drier phloem than larger diameter logs. All logs dried with time but sunlight level did not affect desiccation rates. Ips pini preferred attacking larger logs and the bottom side of logs. Sunlight exposure had a significant effect on net reproductive success in smaller diameter logs, with very little net reproductive success in high‐sunlight exposed logs, and the highest reproductive success was found in small diameter logs in the low‐sunlight treatments.4 Management implications of these results are discussed.

Colonization and extinction patterns of wood‐decaying fungi in a boreal old‐growthPicea abiesforest

SummaryWood‐decaying fungi are ubiquitous and functionally important organisms within forest ecosystems world‐wide, but remarkably little is known of their population dynamics in relation to the dynamics of their host substrates. Living in transient environments, where local extinctions are caused by gradual substrate (patch) destruction or deterioration due to wood decomposition, the long‐term persistence of these species requires successful colonization of new patches.During a 6‐year period, we examined the colonization–extinction dynamics of wood‐decaying fungi (Aphyllophorales:PolyporaceaeandCorticiaceae) in relation to the spatiotemporal distribution of host logs within a boreal old‐growth Norway spruce (Picea abies) forest.The dynamics of the species studied were strongly influenced by both local log characteristics (within patch) and connectivity (between patch). Several species (e.g.Asterodon ferruginosus,Phellinus ferrugineofuscus,P. viticola,Phlebia centrifuga) showed a positive effect of connectivity, mainly colonizing logs in the vicinity of previously occupied logs. This implies that some wood‐decaying fungi may be dispersal limited in terms of successful colonizations. The relative importance of patch conditions and connectivity was however, highly species specific.Our results further illustrate the importance of life‐strategies adopted by species that are present during different stages of wood decomposition. Early colonizers were primarily affected by the stage of decomposition; secondary colonizers were affected by a variety of within patch and/or between patch variables, maintaining high species coexistence within intermediate stages of decay.Phellinus nigrolimitatuswas the dominant polyporous decayer at the final stages of decomposition, clearly gaining a competitive advantage from specializing on highly decomposed wood and having very low mean annual mortality rates.Local extinction rates were higher on small diameter logs than large diameter logs, and generally increased as decay proceeded, illustrating the importance of deterministic patch destruction due to wood decomposition.Synthesis. The fungi‐log study system was highly dynamic, illustrating that both characteristics and spatiotemporal availability of logs are important in explaining the distribution patterns and population dynamics of wood‐decaying fungal communities. The result implies that the dynamics of some wood‐decaying fungi can be characterized as patch‐tracking metapopulations, with connectivity‐dependent colonizations and local extinctions caused by the turnover of the patches.

Log Characteristics and Sawn Timber Recovery of Home-Garden Teak from Wet and Dry Localities of Kerala, India

There is a widely held view among smallholders that teak timber produced from small-scale agroforestry systems, especially home-garden forestry, fetches a lower price than that from conventional plantation forestry. To examine the veracity of this view, the wood quality attributes of teak from two home gardens in the district of Ernakulam (wet site) and Palakkad (dry site) in India were compared to those of forest plantation in Nilambur. The logs were graded using standard timber trade practices into high, medium and low quality as determined by the potential sawn timber grade-yield recovery pattern. Of 96 home garden teak logs (aged 35 years) from wet and dry sites, 59% belonged to timber Grade II–IV and the rest were classified as poles. Grade I logs (export quality) with a girth above 150 cm were not available from either of the homesteads. Faster-grown teak in the wet site produced large diameter logs (dbh 1.37 m) with average diameter of 39.6 cm, which is comparable to that of best site quality in India. In contrast, the average dbh for teak grown in the dry site was 24 cm as compared to the average dbh of 31 cm recorded from the same aged forest plantation in Nilambur. It was found that only 10% of logs belonged to Grade II timber and the rest fell under grades III and IV with more frequent visual defects. The sawn timber recovery percentage was lower for the dry site (66.8%), whereas there was no significant difference in grade from the wet and forest plantation sites, with recovery rates of 76.5% and 78.8%, respectively. The general notion that home garden teak has a large proportion of sapwood seems to be baseless, no significant difference being found between the heartwood-sapwood ratio of home-garden and forest plantation teak. Lack of appropriate silvicultural practices in home-garden forestry caused the production of more defective logs, adversely affecting the market price of timber.