Log End-splitting Research Articles

Phenotyping methodologies of log end splitting in eucalyptus (Eucalyptus spp.)

AbstractThis study addresses the crucial consideration of log end splitting in breeding programmes for treated wood. There is a paucity of research focused on efficiently optimizing the phenotyping process for this particular trait. The study aimed to compare methodologies for log end splitting phenotyping and develop an image‐based crack evaluation approach. Initially, 32 eucalyptus clones underwent phenotyping using manual measurement, digital image analysis and visual evaluation. Results showed similar phenotypic values, but image analysis demonstrated better clone discrimination, reducing evaluation time to 78 h compared to manual measurement. The second part focused on testing convolutional neural network architectures (UNet, LinkNet and FPN) using real and synthetic images. U‐Net exhibited slight superiority based on higher Intersection over Union (IoU) values, exhibiting a high correlation (.89) with true values. This approach significantly reduced evaluation time to approximately 10.15 h, emphasizing its efficiency compared to traditional methods.

Distribution of Growth Stresses in Eucalyptus nitens Maiden Logs Immersed in Water

This study aimed to evaluate the effect of water immersion on the release of growth stresses in 17-year-old Eucalyptus nitens logs. A total of 18 of 90 trees evaluated in the field were selected. The average diameter at the height breast of all the trees was 37 cm. The first section of the tree, from the stump to 2.44 m, was used. Three stress levels (low, medium, and high) were established. Six logs were studied for each level, which was divided into two groups: three for control and three for water immersion. Peripheral longitudinal strains on standing trees, freshly felling, and after the immersion process were determined by an extensometer. The deflection of the sawn timber and log-end splitting before and after air-drying were evaluated. In addition, the distribution of growth stresses was determined. The results showed that deflection, the log-end splitting index, and stress distribution were reduced in the three levels. The water immersion method allowed a reduction of growth stresses in Eucalyptus nitens logs.

Effect of growth stress and interlocked grain on splitting of seven different hybrid clones ofEucalyptus grandis×Eucalyptus urophyllawood

AbstractTrees with high levels of growth stress begin to show log end splits (LES) immediately after harvesting, usually reaching its maximum end split in a week, and these tensions also create splits during lumber manufacturing. Interlocked grain is another characteristic that impacts the properties of eucalyptus wood. The aim of this study was to evaluate the effect of growth stress and interlocked grain patterns on log end splitting of seven different hybrid clones ofEucalyptus grandis × Eucalyptus urophyllaplanted in Brazil. The growth stress indicator (GSI) was measured in standing trees before harvesting. Splits were measured on logs in three different stages, and interlocked grain from wood blocks was obtained across the center of the cross-section. The results showed that LES occurred as soon as the trees were harvested; however, for better selection of clones, LES should be evaluated after a week of harvesting. There were statistically significant correlations for GSI with LES. Clones that presented higher values of interlocked grain tended to develop lower values of GSI and LES. Using GSI and interlocked grain measurements, it was possible to select the most indicated eucalyptus clones for lumber production.

Genetic variation of growth and log end-splitting in second-generation Eucalyptus grandis in Sri Lanka

ABSTRACTEucalyptus grandis is one of the main commercial forest plantation species in the highlands of Sri Lanka. An E. grandis genetic improvement program was initiated in 1995 with the establishment of a first-generation provenance-family trial cum seedling seed orchard (SSO), and several seed production areas (SPAs) using seeds from natural stands in Australia. In 2007 a second generation was initiated, comprising a seed-source/family trial with 132 families from plus-trees selected in Sri Lanka: 72 families from the first-generation SSO, 28 families from two of the first-generation SPAs, and 32 families from plus-trees selected in local plantations. Diameter at breast height (DBH) and tree height measurements were taken at ages 2, 5 and 7 years. Trees from a first thinning conducted just after the 5-year assessment were used for assessment of log end-splitting. Significant differences between seed sources and families within seed sources were observed for individual tree volume but not for log end-splitting. The seed source with the highest 7-year tree volume was the SSO, and the second and third best seed sources were the SPAs. Heritabilities for individual tree volume ranged from 0.04±0.05 at age 2 years (all trial families) up to 0.27±0.12 at age 7 years (subset of the 72 SSO families). Heritabilities for end-splitting were close to zero across all trial families and 0.16±0.15 for the subset of 72 SSO families. Phenotypic and genetic correlations between tree volumes across different ages were positive (favourable) with genetic correlations ranging from 0.39±0.38 to 1.00±0.40. The phenotypic and genetic correlations between individual tree volumes at ages 2 and 5 years with end-splitting at age 5 years were generally positive (unfavourable), with the former ranging up to 0.70 and the latter ranging up to 0.90±0.95. This correlation between tree volume and end-splitting could make simultaneous improvement of these traits difficult. Options for further tree improvement work with E. grandis in Sri Lanka are discussed.

Influence of site, storage and steaming on Eucalyptus nitens log-end splitting

Log-end splitting is one of the single most important defects in veneer logs. We show that log-end splitting in the temperate plantation species Eucalyptus nitens varies across sites and within-tree log position and increases with time in storage. Log-end splitting is one of the single most important defects in veneer logs because it can substantially reduce the recovery of veneer sheets. Eucalyptus nitens can develop log-end splits, but factors affecting log-end splitting in this species are not well understood. The present study aims to describe the effect of log storage and steaming on the development of log-end splitting in logs from different plantations and log positions within the tree. The study was conducted on upper and lower logs from each of 41 trees from three 20–22-year-old Tasmanian E. nitens plantations. Log-end splitting was assessed immediately after felling, after transport and storage in a log-yard, and just before peeling. A pre-peeling steam treatment was applied to half the logs. Site had a significant effect on splitting, and upper logs split more than lower logs with storage. Splitting increased with tree diameter breast height (DBH), but this relationship varied with site. The most rapidly growing site had more splitting even after accounting for DBH. No significant effect of steaming was detected. Log-end splitting varied across sites and within-tree log position and increased with time in storage.

Processing sawn wood from thinned, unpruned 17-year-old Eucalyptus dunnii in southern China

SummarySixty logs of 17-year-old thinned, unpruned plantation-grown Eucalyptus dunnii representing 10 trees from each of 2 provenances were obtained from a field-trial in central Guangxi Province, China, and processed in a nearby sawmill to produce dried appearance-grade sawn wood suitable for manufacture of short-length flooring. This study’s objectives included determining: interrelationships between log end-splitting and growth stress measured on standing trees and important wood behaviour during processing; relationships between log external features and sawn product recovery; the potential for improvement in processing and/or product quality with the application of a steam reconditioning treatment; and differences in product value and processing characteristics between two provenances of E. dunnii.Boards were air-dried and kiln-dried in two matched batches and one batch was subsequently given a steam reconditioning treatment. For prediction of processing characteristics, the measured displacement on standing tree stems associated with growth stress release was moderately useful for prediction of log end-splitting but not significant for any other characteristic tested, and log end-splitting was not a significant predictor of recovery or product value. Log diameter measures and sweep were the only significant predictors of recovery. Diameter was sufficiently large in some logs to meet D-grade requirements according to Australian (VicForests) log grading standards. The estimated mill door values of sawn product obtained per log cubic metre for D-grade and residual-grade logs (below VicForests sawlog specifications) were RMB 1045 and RMB 887, respectively (approximately AUD 190 and AUD 161, respectively). Steam reconditioning treatment significantly reduced cupping and increased width and thickness dimensions but the presence of severe non-drying-related defect limited the direct benefit of the treatment. There was no significant difference between provenances in product recovery, product value or log end-split severity.

Grade and value variations in Eucalyptus urophylla × E. grandis veneer due to variations in initial plantation spacings

SummaryProcessing young, small-diameter eucalypt logs into veneer is a burgeoning industry across southern China. However, plantations supplying these logs are mostly managed on silvicultural regimes which are appropriate for pulpwood and little information is available on alternative regimes for eucalypt plantations with respect to veneer yields and quality. Log size along with a range of tree and log traits were assessed on 12-year-old eucalypts in six spacing treatments, ranging from 666 to 2 222 trees ha−1, in a field trial in southern China. Logs harvested from these were rotary peeled for veneer; recovery percentages plus a range of quality and value traits were assessed on the outturn. Log volumes, small-end diameters and individual log values varied significantly between spacing treatments, but total veneer recoveries (as a percentage of log volume) and veneer values per unit volume did not. The spacing treatment providing the highest veneer value per unit area was that with the highest stocking; 2 222 trees ha−1. Although the second logs (up from the butt log) had significantly lower average volume than butt logs, and they had significantly higher average value per unit volume because of higher average total veneer recovery (68.7%) compared with the butt logs (59.7%). A number of external log features were significantly correlated with veneer value per unit volume and total veneer-recovery percentage. In declining order of importance these were taper, sweep, number of visible epicormic stubs, number of bumps and visible branch stubs, and longitudinal growth strain in the outer-wood. Branch-related defects were the most important grade-limiting defect, limiting veneer sheet quality to D-grade for most sheets. Considerable improvement in veneer sheet quality may have been achieved by pruning either just before or after branch death. Mill-door prices for logs were calculated after accounting for processing costs obtained from the mill and averaged RMB774 m−3 (about A$126 m−3). Had the trees been pruned, simulations indicated that prices/values could be lifted by RMB60–128 m−3 (A$10–21 m−3) and RMB393–461 m−3 (A$63–74 m−3) for production of higher-quality structural veneer and appearance-grade face veneer, respectively. It appears feasible that improvement in mill-door log values is possible with production of appearance-grade face veneer, but this will require some improvement in log quality through silvicultural intervention with pruning. It will also require improvement in processing methods and reduction in the impact of log end-splitting on veneer quality.

Avaliação da segurança e ocorrência de defeitos na operação de corte semimecanizado de florestas de eucalipto

Avaliou-se a operação de corte semimecanizado nos aspectos de segurança no trabalho de operadores de motosserra e na qualidade da madeira derrubada, visando validar as recomendações técnicas da literatura especializada. O estudo foi realizado em povoamentos de Eucalyptus grandis com idade de 9 anos plantados em espaçamento 3 x 2 m, na Estação Experimental Fazenda Água Limpa (FAL), pertencente à Universidade de Brasília. Foram estabelecidos procedimentos relativos à técnica de derrubada de árvores. O tratamento-testemunha foi executado segundo as recomendações técnicas da literatura especializada. Os demais tratamentos variaram em relação à profundidade e ângulo de execução da boca de corte e, também, à altura de execução do corte de queda das árvores. Avaliaram-se a segurança da operação, ocorrência de rachaduras de topo, formação de espetos e volume de madeira remanescente na cepa, sendo os tratamentos comparados pelo teste de Dunnett. Pelos resultados, o tratamento-testemunha mostrou-se a melhor alternativa técnica para a derrubada de árvores de eucalipto com motosserra, nos aspectos de segurança e qualidade da madeira.

Genetic variation in traits affecting sawn timber recovery in plantation-grown Eucalyptus nitens

& Introduction There is increasing interest in managing Eucalyptus nitens plantations for sawn timber production. & Aims This study aimed to determine the potential for genetic improvement of traits affecting green sawn board recovery in plantation-grown E. nitens. & Methods The study was undertaken on an E. nitens progeny trial. All trees were measured for diameter at breast height (DBH) and stem straightness, and 560 trees were selected for timber processing. Assessment was made of survival, log and green sawn board volume, log taper, and both upper and lower log end splitting. Genetic variation in and between these traits was estimated. & Results Geneticdifferencesamongracesweresignificantfor DBH at years 9 and 14, stem straightness, log taper and green sawn board volume. Within-race, narrow-sense heritabilities were significant for DBH, stem straightness, log volume, and both upper and lower log end splitting. Positive and significant additive genetic correlations were observed between DBH at all ages and survival, stem straightness and log volume. Significant adverse genetic correlations were shown between upper log end splitting and DBH at years 9 and 14. & Conclusion These findings showed that harvest-age stem straightness and log volume objective traits in E. nitens are amenable to genetic improvement and that selection for early-age DBH in breeding programmes should improve harvest-age survival, stem diameter and straightness, as well as log and green sawn board volume. However, these improvements are likely to be countered to some extent by increased end splitting of logs from larger trees.

Longitudinal growth strain as a log and wood quality predictor for plantation-grown Eucalyptus nitens sawlogs

Peripheral longitudinal growth strain (LGS) was measured on a total of 81, 22-year-old pruned Eucalyptus nitens trees from five thinning treatments in a plantation thinning trial in Tasmania. Growth strain data were gathered at breast height on each tree using the CIRAD-Foret method. The effects of thinning treatment and tree diameter on LGS and its relationships to solid-wood traits determined in a processing trial were examined. LGS was significantly higher in the direction of the prevailing wind and was not significantly affected by either thinning treatment or tree diameter. An index of log end splitting was positively related to tree diameter, sawlog position (upper/lower), and LGS, which explained up to an additional 20% of the variance after tree diameter and log position were accounted for in a linear regression model. High LGS and log end splitting were significant indicators of increased board end splitting.

Clonal differences in log end splitting in Eucalyptus grandis in relation to age, parent performance, growth rate and wood density in two even-aged trials in Mpumalanga, South Africa

This paper discusses the juvenile–mature correlation of log end splitting among Eucalyptus grandis clones from two trials and how differences in splitting relate to differences in wood density, pith-to-bark gradient and growth rate. Two approximately 20-year-old Eucalyptus grandis clonal trials at Bergvliet plantation were sampled. The first trial (Trial A) consisted of clones of eight ortets (genotypes) specifically selected for their widely different propensities to develop end splitting. The second trial (Trial B) consisted of 80 clones and one seedling control. From the latter trial 15 clones were selected in such a manner that they constituted three groups of clones representing a combination of high- and low-volume producers and, among the high-volume producers, clones exhibiting high and low propensities towards end splitting. The fourth group represented the seedling control. Trial A showed highly significant clonal differences in splitting, basic wood density, as well as its pith-to-bark gradient. No relationship of splitting with differences in growth rate, density or density gradient was found. The clones derived from the low- and high-splitting ortets maintained their general statuses as low and high splitters over a considerable period of time, but some of the individual clones did not reflect the performance of the ortets from which they were derived. Trial B revealed that clones classified as good-volume producers at the age of 65 months still outperformed the clones classified as low-volume producers approximately 15 years later. No significant differences in average wood density between the groups of clones studied was found, irrespective of differences in growth rate and degree of splitting, but trees from the slow-growing group of clones were significantly more variable across the radius in average wood density. The outcome of both trials confirmed results of many previous studies on this species, in that rapid and uniform growth has no significant detrimental effect on wood density or its rate of change across the radius of the tree. It may, in fact, be associated with increased uniformity from pith to bark with increasing age, sometimes resulting in slightly increased overall wood density.

Estimates of genetic parameters of wood traits for sawn timber production in Eucalyptus grandis

In this study, the breeding perspectives of 41 open-pollinated progenies of Eucalyptus grandis were evaluated based on their wood traits. The progenies were distributed in two experiments in a randomized complete block design, with three replicates and linear plots containing six plants each. The traits were assessed at eight years of age. Two trees from each plot were selected for this assessment based on better growth, stem form and phytosanity. Significant differences in basic density, sapwood/heartwood ratio, bowing, specific gravity, parallel compression and static bending were detected among the progenies. These traits were potentially promising for breeding programs, with heritability coefficients that varied from 0.34 to 0.61 on a progeny mean basis. There was no genetic variation in the moisture content, board end-splitting, log volume under bark, log eccentricity, bark content, crooking, and shear strength of the progenies. Intermediate to highly significant genetic correlations were detected among the physical and mechanical properties, as well as between pairs of traits such as basic density and log end-splitting, basic density and bowing, specific gravity and bowing, sapwood/heartwood ratio and bowing, log volume and bowing, and log volume and log end-splitting. These results show that the levels of growth stress in trees can be reduced by selection using indirect traits such as the sapwood/heartwood ratio and bowing.

Relationships between surface growth strain and some tree, wood and sawn timber characteristics ofEucalyptus cloeziana

SYMMARY To assess the utility of the CIRAD-Fort% growth strain gauge for estimating stein growth stress, the relationship of longitudinal growth strain (LGS) with log-end splitting, sawn timber distortion and other tree and wood properties was studied in 23 ten-year-old Eucalyptus cloeziana trees. The CIRAD-Foret growth strain gauge appears to be useful as a means of predicting sawn timber distortion in young E. cloeziana trees. LGS correlated well with bow and spring and accounted for 50 and 30% of the respective total variation. The relationships of LGS with log end splitting, wood density, tree diameter and height were weak. However, distinct differences in wood density and sawtimber distortion were observed between trees with low and high strain. Trees with high growth strain were generally smaller with wood of significantly higher basic density and bow. Sampling position around the stem was not important and LGS increased with tree height.

Tree Breeding in Support of Vegetative Propagation ofEucalyptus grandis(Hill) Maiden

SYNOPSIS Eucalyptus grandis is the most important species supplying timber to the market in South Africa. However, serious timber defects, especially high growth stresses resulting in log end-splitting, reduce the percentage recovery in converting logs to solid wood products. Breeding trials have indicated that substantial genetic improvement is possible in growth rate, stem straightness, splitting of logs, penetration of preservatives and even in rootability of cuttings. Moreover, recent success in clonal forestry brought renewed enthusiasm for obtaining large gains through vegetative propagation. However, while gains from vegetative propagation may far exceed gains from sexual breeding the former is “one-off” in nature. Unless new genotypes with superior characteristics are created the gains obtained from clonal forestry will become stagnant. This paper emphasises the need for the maintenance of genetic diversity and continued breeding. It shows that genetic information from family trials will aid in ef...

“Provenance” Variation in Growth Features ofEucalyptus grandisandEucalyptus salignain South Africa

SYNOPSIS The preliminary results of a series of Eucalyptus grandis and E. saligna ‘provenance’ studies are discussed. Poor provenance representation is evident by the small number of mother trees represented within some seedlots, disqualifying the latter from being designated as truly typical of a provenance. Further trials using a more efficient design and seedlots of truer provenance representation is recommended. E. grandis seedlots from Coffs Harbour, New South Wales constantly rank among the top volume producers, while seedlots from the South African E. grandis seed orchards is not outstanding in standing volume production when compared with the Australian seedlots. The real effect of the lower volume however will become evident when the trials are clearfelled and assessed for log end splitting. On the other hand, definite improvements in stem-form in E. grandis appear to have been achieved from the South African breeding programme. E. saligna seedlots perform variably, but as a whole tend to produce...