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Article

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

by
Carlos Rozas
1,*,
Ricardo Burgos
1,
Alexander Opazo
1,
Pablo Moreno
1,
Oswaldo Erazo
1 and
Jean Pierre Lasserre
2
1
Department of Wood Engineering, Faculty of Engineering, University of Bío-Bío, Concepción 4030000, Chile
2
CMPC Forestal Mininco S.A., Concepción 4030000, Chile
*
Author to whom correspondence should be addressed.
Forests 2023, 14(8), 1517; https://doi.org/10.3390/f14081517
Submission received: 16 May 2023 / Revised: 4 July 2023 / Accepted: 5 July 2023 / Published: 26 July 2023
(This article belongs to the Special Issue Physico-Mechanical Properties of Lignocellulosic Material and Its Application)
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Abstract

:
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.

1. Introduction

The plantations of the genus Eucalyptus in Chile have increased in the last decade, mainly due to new industrial pulp projects, which are based on short-fiber wood production. According to [1], the accumulated area of plantations by December 2019 was 2,321,257 hectares, increasing by 0.8% over the planted area in 2018. Pinus radiata is the species concentrating 56% of the total planted area, around 1,299,451 ha, followed by Eucalyptus with 36.8%, of which 11.8% and 25% were for Eucalyptus nitens and Eucalyptus globulus, respectively. The total area for Eucalyptus was 854,539 ha. Other species covered 7.2%, approximately 167,000 ha. It is expected to have an availability of 19 million solid cubic meters without bark (SSC) between the E. globulus and E. nitens species for the period of 2023–2025 [1].
In 2019, there were 580,726 hectares of Eucalyptus globulus and 273,867 hectares of Eucalyptus nitens planted in Chile [1]. Eucalyptus is the third commercially important forest species in Chile [2] and has the highest growth rate recorded not only in Chile but in the world (up to 77 m3/ha/year) [3]. Furthermore, the Eucalyptus genus has a basic density ranging from 490 kg⸱m−3 to 520 kg⸱m−3 and has a high tolerance to low temperatures [3,4,5]. These characteristics make Eucalyptus an excellent raw material for the pulp and paper industry [6]. However, the mechanical processing industries has had difficulties in producing products with higher added value due to some limitations and unfavorable features such as relatively high shrinkage, susceptibility to collapse during drying, and mainly the presence of growth stresses, which produce defects in logs such as end-splitting, cracks, and warping during and after sawing [7,8]. These drawbacks affect the lumber quality. Therefore, the use of Eucalyptus for the production of wood products presents a major technological challenge.
According to [9,10], once the trees have been cut down, the high growth stresses are released, causing three main defects: log end splitting after felling, warping and longitudinal splits in both logs and boards during the sawing process, and brittle heartwood resulting from excessive compressive stress, limiting the use of this wood.
Several methods to reduce growth stresses have been used; however, none of them have been considered entirely satisfactory [11]. Among the methods used to release growth stresses are the use of metal or plastic straps [12], gang nail-type metal connectors and S- or C-shaped hooks [13], chainsaw banding, and the drying technique applied to the standing tree [9,14], the application of temperature (water or steam) to logs [14,15,16,17,18], and different cutting directions such as the radial and tangential cuts of two symmetrical sides [19,20,21,22].
Wood stored underwater has often been recommended as a method to reduce log end splitting. For example, Eucalyptus robusta stored under a sprinkler system for 3.5 months significantly reduced splitting, staining, and insect attack [23]. Nicholson (1972) found a reduction of 20% in log end splitting after storing Eucalyptus regnans logs for 300 days under water spray [9]. Similarly, ref. [24] mentioned that sprinkler irrigation allowed a 15 to 20% reduction in stress intensity and a reduction in warping during sawing. However, ref. [13] concluded that there was no increase in splitting in the logs stored both in water and under sprinklers. Still, there was a significant decrease in internal stresses as the storage time of logs under total immersion increased.
The simplest way to assess the general level of growth stresses in trees is after felling. It allows following the evolution of the splitting. However, it is not an exact assessment, but qualitative. It depends on the stress level, tree diameter, pre-existing central cracks, and the impact when the tree is overturning. This system has been used by [25,26,27,28]. On the other hand, there are indirect ways to evaluate the magnitude of stresses by measuring the board deformations caused during and after sawing, log-end splitting index, dimensional variation, warping in the sawn timber, etc., [14,29].
The extensometer, developed by CIRAD-Forêt in France (Centre de Coopération Internationale en Recherche Agronomique pour le Développement Département des Forêts), is one of the most widely used non-destructive methods for measuring longitudinal growth stresses. This instrument measures the residual longitudinal strain at a fixed distance, which is directly proportional to the growing stress in the longitudinal direction. This method has been reported by [17,22,30,31,32,33,34,35,36,37].
The peripheral longitudinal strains in logs are considered the most significant estimator of growth stresses. The longitudinal stresses, therefore, are defined by the product of this peripheral longitudinal strain or fibers displacement measured in the tree and the elastic modulus of wood [4]. According to [38], the theory of growth stress distribution from the bark to the pith is explained by the determination of a tensile-compression gradient in this direction. This gradient establishes that the magnitude of the stresses measured at the log periphery varies when considering the distance from the pith to the estimate and the log radius. Ref. [39] proposed a modification of the Kübler model [38], as the stresses that cause the bending of sawn wood, which is obtained by simultaneous cuts, and have a linear distribution.
The use of Eucalyptus nitens wood has been mainly focused on pulp and paper production, with limited production of sawn timber and veneer. Therefore, obtaining higher value-added products is quite a challenge. This research approached an integrated process that must necessarily begin in the forest from the cutting and transportation of logs (growth stresses-tree segregation) to the sawing process (including immersion treatment in water to reduce growth stresses), up to the drying process. Undoubtedly, the most significant scientific contributions of this research are based on the stress relief method, which has not been applied to this species in Chile; on the other hand, the vision of an integrated process that allows diversifying the utilization of Eucalyptus nitens plantations. Therefore, the objective of the study was to evaluate the effect of water immersion on the release of growth stresses in 17-year-old Eucalyptus nitens wood pieces with an average DBH of 37 cm. This was assessed through deflections and end splitting in the boards, with the growth stress profile also determined through mathematical equations.

2. Materials and Methods

2.1. Obtaining and Measurements of the Log Peripheral Longitudinal Strains

Eighteen Eucalyptus nitens trees, aged 17 years old and diameter at height breast of 37 cm, were selected from a plantation with a density of 1660 trees/ha. Trees were obtained from Hacienda Rucamanqui, owned by Forestal Mininco S.A., in Yungay, VIII-región, Chile. The first section of the tree, from the stump to 2.44 m, was used. Nine logs were immersed in water for 12 months (Figure 1a). After finishing this time, nine trees, additionally, were cut down to be used as control or untreated logs (Figure 1b). Log ends were sealed with Mobilcell to reduce the water release while transporting to the University of Bío Bío, Chile.
The logs were classified into three growth stress categories based on the strain level of the standing trees: low, medium, and high. The classification considered the results of Mutizabal [40] and Riquelme [41], who found values of DRL ranging from 0.020 mm to 0.187 mm and 0.073 mm and 0.262 mm, respectively. However, in this research, the range used was wider (0.000–0.507), which is presented for each level in Table 1.
The peripheral longitudinal strains (PLS) were measured by a CIRAD-Forêt extensometer (Figure 2). The measurements were carried out in 3 phases. The first one was performed on the standing tree at the height of 1.30 m, using two rectangular windows of approximately 10 × 60 cm and following the North–South direction. A rectangular window is a rectangular area made in the standing tree after the removal of a bark window. In this section, the extensometer is placed. The window dimensions are associated with the size of the device. The bigger the devices are, the bigger the windows are. The second one was conducted after the tree was overturned and in the first section of the log (2.44 in length) in windows 3 and 4, following the East–West direction. The above process was also carried out on the nine control logs. Finally, the third phase was performed on the logs that were immersed in water, evaluating windows 3 and 4; orientation was random because marks in windows 1 and 2 were not recognized visually due to logs kept in water for an extended period of exposure.

2.2. Sawing Process and Lumber Deflection Measurements

Considering lower diameter, logs were cut tangentially by using a band sawmill. The saw sliced pieces from the log at 30 mm thick until the log was turned into a 40 mm central beam. A total of 151 boards were obtained. The boards were identified, and wood warping was measured according to the Chilean Standard NCh992.EOf72 [42]. According to the wood warping level, the log deflection values were compared and sorted based on the Chilean Standard NCh993EOf72 [43]. The average wood basic density and moisture content was 520 kg⸱m−3 and 112.6%, respectively.

2.3. Determination of End Splitting Index in Boards

The end splitting index for 151 boards was recorded. Board end splits after sawing were measured. End splitting index was calculated for each board using Equation (1).
I R % = ∑ b o a r d   e n d   s p l i t s   l e n g t h b o a r d   t o t a l   l e n g t h .

2.4. Growth Stress Distribution Assessment

Growth stress distribution in the pith-bark direction was calculated using Equations (2) and (3) by [38,39], respectively.
σ r = σ p 1 + 2 l n r R ,
σ r = σ p − 2 + 3 r R .
Stress was determined based on Hooke’s law using Equation (4)
σ x = E c x × ε x ,
where:
σr: Stress at a point r between the pith and the periphery of the log or board (kg/cm2).
σp: Stress in the log or board periphery (kg/cm2), where; σp = Ecp × εp.
r: Variable going from zero (pith) to in the log periphery (cm).
R: Radius of the log (cm).
Ecx: Modulus of elasticity in compression parallel to the grain determined by mechanical tests. (x: radial variation; between pith and bark). x = p; periphery.
εx: Peripheral strain determined by an extensometer (x: radial variation; between pith and bark). x = p; periphery.
Growth stress distribution in the pith–bark direction was also estimated using Equation (5).
σ r e = 157,957.84 ρ b 0.944 + 358.72 C H 0.853 × ε p − 0.060514 R 0.075 − r 0.075 .
The modulus of elasticity in compression parallel to the fibers (Equation (6)) was determined for samples taken in the pith–bark direction from the 18 logs used in this study and according to the Chilean Standard NCh 973Of.86 [44].
E c r = 157,957.84 ρ b   0.944 + 358.72 C H 0.853  
This modulus is a function of the basic density (ρb) and the moisture content (MC), which were determined according to the Chilean Standard NCh176/2Of.86 [45] and NCh176/1Of.84 [46], respectively. The modulus of elasticity is valid for basic density values between 700 kg⸱m−3 and 350 kg⸱m−3 and moisture content values between 175.0% and 61.3%. This was used to determine the modulus of elasticity in the radial direction of each log. The ordinary least squares method was used by the Excel Solver tool. To determine the radial deformation, the equation of Jacobs [39] was used, which is expressed as follows (Equation (7)):
ε r = ε p − 0.060514 R 0.075 − r 0.075 .
In this research, 18 Eucalyptus nitens trees were used. A total of 9 trees were used as controls and the remaining trees were treated. After cutting down the trees, logs were obtained. Similarly, 9 logs were used as controls and the other 9 were immersed in water. The statistical setting considered three levels of stress (low, medium, and high). Three replications were conducted for each level of stress. Each stress level was compared to the control trees.

3. Results and Discussion

3.1. Peripheral Longitudinal Strain

Figure 3 shows the values of peripheral longitudinal strains (PLS). The average PLS for standing trees was 0.148 mm after felling was 0.147 mm and 0.141 mm after immersion in water. From the PLS results, in the trees freshly felled and with no treatment, it can be observed that there was an increase of 24% and 14% in the low and medium stress levels, respectively. Concerning the high-stress level, there was an increase of 4% compared to the PLS of standing trees.
However, in logs immersed in water, there was an increase of 19% and 17% in the low and medium stress levels, respectively, and a decrease of 10% compared to standing tree measurements. Overall, PLS increased by 4% in the logs with water treatment and 7% in felled trees concerning standing tree measurements. This increase was because measurements were taken at different points when measured in the standing trees. Therefore, both measurements did not necessarily match each other because the stress distribution is not symmetrical [22]. The measurements were not taken at the same points because they were made in the North–South orientation of the standing trees. According to the methodology, a hole is made in the standing tree to measure the PLS. Once the tree is felled, the PLS must be measured on the opposite side, that is, in the East–West orientation.
These values can be compared with those obtained by [30], who studied the variability of tree growth stresses in the Chilean plantations of Rucamanqui and Collipulli. The author found that PLS values were between 0.17 and 0.32 mm in 13-year-old Eucalyptus nitens trees and claimed that there were significant differences between both locations. On the other hand, ref. [22] studied PLS in Eucalyptus globulus trees from 23-, 27-, and 32-year-old plantations in Galicia, Spain, finding values of 0.140 mm, 0.129 mm, and 0.092 mm, respectively. Finally, ref. [4] researched Eucalyptus nitens in Chile: Developing high-value forestry, in which he analyzed the values of the periphery longitudinal strain in Eucalyptus nitens trees from four different locations, but from the same site. The author sorted the PLS average values in low ranging from 0.081 to 0.127 mm, medium from 0.173 to 0.202 mm, and high from 0.241 to 0.433 mm. Moreover, ref. [4] concluded that the behavior of the PLS of samples was distributed in a wide range of values for each origin. The author also found that there was no significant relationship with the diameter at breast height, but so there was a substantial and positive relationship with splits in logs and sawn lumber.

3.2. Warping

Wood warping can be influenced by various factors including the wood species, grain orientation, MC changes, temperature variations, etc. In the case of eucalyptus, warpings are attributed to MC changes produced from the felling of the tree to sawing process. Table 2 shows the type of warping, number, and proportion of green boards after sawing according to the Chilean Standard NCh 993Of72 [43]. Most of the wood, both immersed in water or not, was classified in levels B and C. Only 32 boards were left out of the standard due to the crook defect.
The classification values of the woods are compared with the industrial pre-drying study of Eucalyptus conducted by Garay [47]. In this study, the quantification of defects in the wood pieces was performed. The results were as follows: For bowing deformations: 93% of the pieces had a mild defect and 7% had no defect. For crook deformations, 12% of the pieces had a severe defect, 33% had a regular defect, 35% had a mild defect, and 20% had no defect. For twist deformations, 99% of the pieces had no defect, and 1% had a mild defect.
Figure 4a,b shows the behavior of the average deflection values for the different warpings in wood immersed in water and without treatment, following the bark-to-bark direction. In addition, a decline in the bark–pith direction is observed for both defects bowing and twisting, while for crooking, there was an increase in the bark–pith direction.
Significant reductions in the deflection of warping of the water-treated boards, reaching 30% in bowing, 41% in crooking, and 28% in twisting, were observed. These values are like those found by [48], who studied the solar drying between two species from a plantation in Uruguay, Eucalyptus tereticornis and Eucalyptus camaldulensis, aged 60 and 70 years old, and diameter at breast height of 57 cm and 59 cm, respectively. The average warping values in both species were for cupping 1.5 mm, for bowing 7.6 mm in Eucalyptus tereticornis and 7.0 mm for Eucalyptus camaldulensis, for crooking 5.5 mm in Eucalyptus tereticornis, and 7.5 mm for Eucalyptus camaldulensis. Concerning twisting, there was no for Eucalyptus tereticornis, while in Eucalyptus camaldulensis, twisting reached 3 mm. It is evident that the values of bowing were reduced for both species after the drying process, and there was not a significant increase in the other defects.
The classification values of the woods were compared with a study on industrial pre-drying of Eucalyptus [47]. The bowing, crooking, and twisting defects of the pieces were studied before drying. Regarding bowing deformation, it was found that 46 pieces with no defect and 54 pieces with a slight defect. However, for crooking, the number of flawless pieces was lower, only 26, while 54 pieces had a slight defect, 18 had a regular defect, and 8 pieces with a strong defect. For the twisting deformation, it was found that 98 pieces with no defect, and two pieces had a slight defect.

3.3. End Splitting Index (ESI%)

Figure 5a shows the behavior of the log-end splitting index along the pieces with and without water treatment in the bark-to-bark direction. Concerning untreated pieces, there was an increase in the ESI% of pieces immersed in water, in the bark to pith direction, with 8% reached in the low-stress level, but ESI% decreased by 15% and 12% in the medium and high-stress levels, respectively.
The ESI% after natural drying increased from the bark to the pith direction (Figure 5b). Compared to untreated wood, the pieces immersed in the water had an increase of 16% in the low-stress level, a decrease of 18% in the medium-stress level, and a 6% in the high-stress level.
The reduction of the end-splitting index was similar to the results found by [29], who carried out a study based on the effect of log steaming on the reduction of defects associated with growth stresses in Eucalyptus grandis, achieving a log end-splitting reduction of 34.7% for logs from 30 to <35, 34.8% for logs from 25 to <30, and 34.1% for logs from 20 to <25 cm in diameter, respectively. Furthermore, Nicholson, 1973 conducted a study related to the application of water spray irrigation to Eucalyptus regnans logs for the release of growth stresses for 300 days, in which it found a reduction of up to 20% in the intensity of log-ends.
On the other hand, Table 3 shows the total number of end-splitting in boards with and without water treatment, according to the stress levels. Figure 4 and Figure 5 show the percentage of end splitting found in the 151 boards with and without water treatment. Splits were observed at the ends of the boards in both water-treated and untreated conditions; however, the maximum number of splits was found in the boards of the water-treated logs, with 84%, either at one end or at both ends.

3.4. Growth Stress Distribution

Figure 6a,b shows the growth stresses in the radial direction of the specimens of the central beam immersed in water and control, which were determined by [38]. It is shown that there were both tensile and compressive stresses at the ends of the trees, increasing from the bark to the pith. In addition, the three stress levels were reduced in the logs with water treatment. For the control logs, there were a decrease of 38 kg⸱cm−2 in the low-stress level, 82 kg⸱cm−2 in the medium-stress level, and 72 kg cm−2 in the high-stress level.
The behavior of the growing stresses in the radial direction of the specimens from the central beam with and without water treatment is shown in Figure 7. These values were determined by the model of García [39]. There is a compression zone towards the pith of the logs and tensile stress towards the periphery of the logs. In addition, reductions of 53 kg⸱cm−2 in the low-stress level, 71 kg⸱cm−2 in the medium-stress level, and 34 kg⸱cm−2 in the high-stress level were obtained concerning the untreated condition.
Overall, the stress distributions in the water-treated log (determined by Equations (2) and (3) decreased in the three stress levels. However, this decrease was higher in the medium-stress level of the water-immersed trees concerning untreated trees. It is important to mention that the Kubler and Garcia models underestimate the tensile stresses. In Kubler’s model, compression stresses are amplified and tend to be closer to Garcia’s model.
Regarding the model estimated here in this study, which was based on the ordinary least square method (OLS), the growth stresses in the bark-to-bark direction of the boards with and without water treatment showed a reduction in the three stress levels concerning the control boards (Figure 8). The values were 4 kg⸱cm−2 in the low-stress level, 13 kg⸱cm−2 in the medium-stress level, and 14 kg⸱cm−2 in the high-stress level. Therefore, the model proposed in this research can represent a better way for the distribution of stresses in the radii. This can be corroborated by the distribution of deflections experienced by the boards radially.

4. Conclusions

The segregation of trees based on the levels of peripheral deformations was adequate, clearly highlighting the three considered stress levels (low, medium, and high). However, the measurements of deformations in the logs were random, with some being of greater or lesser magnitude. The average values of peripheral longitudinal deformations showed a slight decrease due to the applied treatment, measuring 0.148 mm in the standing tree, 0.147 mm after felling, and 0.141 mm after water immersion, being the greatest effect observed in the highest stress level. The proposed model in this research allowed for a better prediction of the distribution of growth stresses in the radial direction compared to the Kubler and Garcia models, which was corroborated by the deflection distribution of the boards after sawing. The immersion of logs in water reduced growth stresses, resulting in a 15% and 12% decrease in the splitting index after sawing for medium and high-stress levels, respectively, compared to untreated boards. This reduction trend was maintained for these levels after drying, with 18% and 6% reductions, respectively. Additionally, this treatment achieved a reduction in warping in all the stress levels, with a greater decrease observed for bowing, twisting, and cupping in the medium and low-stress levels, respectively. The water immersion treatment allowed for the reduction of growth stress levels in logs, demonstrating that this treatment can be an alternative to increase the productivity of Eucalyptus nitens plantations for higher value-added products.

Author Contributions

Conceptualization, C.R. and R.B.; methodology, C.R., R.B., A.O. and J.P.L.; validation, C.R., R.B. and A.O.; formal analysis, C.R., R.B., A.O. and P.M.; investigation, C.R., R.B. and J.P.L.; resources, C.R. and R.B.; data curation, C.R., R.B., O.E. and P.M.; writing—original draft preparation, C.R., R.B., P.M. and O.E.; writing—review and editing, C.R., O.E., P.M., R.B., A.O. and J.P.L.; visualization, C.R., R.B., O.E. and P.M.; supervision, C.R. and R.B.; project administration, C.R. and R.B.; funding acquisition, C.R., R.B. and J.P.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by CMPC Forestal Mininco S.A. and the Regular Project 095512 1/R, University of Bío-Bío, Chile.

Data Availability Statement

The data presented in this article are available upon reasonable request from the corresponding authors.

Acknowledgments

The Authors would like to acknowledge to CMPC-Forestal Mininco Company, Planta Los Angeles for providing the material for this study and to their personnel. We also want to thank to the Regular Project 095512 1/R from University of Bío-Bío, Chile: “Prediction of the degree of deformation in sawn wood of Eucalyptus nitens considering the level of growth stresses.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Aguirre, D.; Gysling, J.; Kahler, C.; Poblete, P.; Álvarez, V.; Pardo, E.; Bañados, J.C.; Baeza, D. Anuario Forestal 2021. Instituto Forestal, Chile. Boletín Estadístico 2021, 180, 257. [Google Scholar]
  2. Trincado, G.; Lasserre, J.-P. El Desarrollo Del Eucalyptus Nitens. Chile For. 2005, 309, 25–29. [Google Scholar]
  3. Barros, S.; Rojas, P. Crecimiento y Rendimiento. In Eucalyptus Principio de Silvicultura y Manejo; Padro, J., Barros, S., Eds.; Instituto Forestal Chile-CORFO: Santiago, Chile, 1989; pp. 101–145. [Google Scholar]
  4. Pinilla, J. Informe Técnico 165: Eucalyptus Nitens En Chile: Primera Monografía; INFOR: Santiago Metropolitan, Chile, 2004. [Google Scholar]
  5. Molina, M.P.; Ipinza, R.; Gutiérrez, B.; Emhart, V.; Borralho, N. Estrategia de Mejoramiento Genético Para La Utilización de Eucalyptus Nitens Como Madera Sólida. Avances En La Selección de Árboles. Cienc. Investig. For. 2018, 24, 33–46. [Google Scholar] [CrossRef]
  6. Cheng, Y.; Chan, A.H.C.; Holloway, D.; Nolan, G. Anisotropic Material Behaviour under Compression of Eucalyptus Nitens with High Moisture Content. Constr. Build. Mater. 2022, 314, 124788. [Google Scholar] [CrossRef]
  7. Yang, J.L.; Waugh, G. Growth Stress, Its Measurement and Effects. Aust. For. 2001, 64, 127–135. [Google Scholar] [CrossRef]
  8. Derikvand, M.; Nolan, G.; Jiao, H.; Kotlarewski, N. What to Do with Structurally Low-Grade Wood from Australia’s Plantation Eucalyptus; Building Application? BioResources 2017, 12, 4–7. [Google Scholar] [CrossRef] [Green Version]
  9. Nicholson, J.E. Effect of Storage on Growth Stress in Mountain Ash Logs and Trees. Aust. For. 1972, 36, 114–124. [Google Scholar] [CrossRef]
  10. Omonte, M.; Valenzuela, L. Tensiones de Crecimiento Longitudinales En Árboles de Eucalyptus Nitens Con Dimensiones Aserrables. Maderas. Cienc. Tecnol. 2015, 17, 673–684. [Google Scholar] [CrossRef] [Green Version]
  11. Chafe, S. Growth Stress in Trees. Aust. For. Res. 1979, 9, 203–223. [Google Scholar]
  12. Kübler, H.; Chen, T.-H. Prevention of Crosscut and Heating Heart Checks in Log Ends. Wood Sci. Technol. 1975, 9, 15–24. [Google Scholar] [CrossRef]
  13. Aguiar, O. Prevencao e Controle das Rachaduras de Topo em Tora de Eucalyptus Grandis Hill ex Maiden. Master’s Thesis, Universidad de São Paulo, Piracicaba, Brasil, 1986. [Google Scholar]
  14. Rozas, C. Contribuicao ao Desenvolvimento Tecnologico Para a Utilizacao de Madeira Serrada de Eucalyptus Grandis (Hill Ex Maiden) Na Geracao de Produtos Com Maior Valor Agregado. Master’s Thesis, Universidade Federal Do Paraná, Curitiba, Brasil, 1993. [Google Scholar]
  15. Weik, B.; Wengert, E.; Schroeder, J.; Brisbin, R. Practical Drying Techniques for Yellow-Poplar S-D-R Flitches. For. Prod. J. 1984, 34, 39–44. [Google Scholar]
  16. Okuyama, T.; Kanagawa, Y.; Hattori, Y. Reduction of Residual Stresses in Logs by Direct Heating Method. J. Japan Wood Res. Soc. 1987, 33, 837–843. [Google Scholar]
  17. Pádua, F.; Trugilho, P.; Rosado, S.; Lima, J.; Júnior, A.; Oliveira, A. Estimativa de Parâmetros Genéticos Das Tensões de Crescimento Em Clones de Eucalyptus. Sci. For. 2004, 66, 52–160. [Google Scholar]
  18. Rozas, C.; Vasquez, M.; Vega, P.T.; Sinha, A.; Montero, C. Effect of Log Heat Treatment on Release of Growth Stresses in Eucalyptus Nitens. Wood Fiber Sci. 2021, 53, 178–193. [Google Scholar] [CrossRef]
  19. Berengut, G. Desdobro Do Eucalipto Saligna (Ensaio). Bras. Madeira 1976, 2, 42–44. [Google Scholar]
  20. Freitas, A.; Ponce, R. Madeira Serrada de Eucalipto. V Encontro Nacional de Reflorestadores. Gramado/Canela/RD. J. dos Reflorestadores 1979, 1, 24–25. [Google Scholar]
  21. Montagna, R.; Ponce, R.; Fernandes, P.; Ribas, C. Desdobro de Eucalyptus Grandis Hill Ex Maiden Visando a Disminuir o Efeito Das Tensoes de Crescimento. Rev. Inst. Florest. 1991, 3, 181–190. [Google Scholar] [CrossRef]
  22. Touza, M. Tensiones de Crecimiento En Eucalyptus Globulus de Galicia (España). Influencia de La Silvicultura y Estrategias de Aserrado. Maderas. Cienc. Tecnol. 2001, 3, 68–89. [Google Scholar] [CrossRef]
  23. Malan, F. Studies on the Phenotypic Variation in Growth Stress Intensity and Its Association with Tree and Wood Properties of South African Grown Eucalyptus Grandis (Hill Ex Maiden). Ph.D. Thesis, University of Stellenbosch, Stellenbosch, South Africa, 1984. [Google Scholar]
  24. Tuset, R.; Duran, F. Manual de Maderas Comerciales, Equipos y Procesos de Utilización; Hemisferio Sur.: Montevideo, Uruguay, 1979. [Google Scholar]
  25. Rozas, C.; Morales, M.; Vargas, G.; Yáñez, R. Estudio Preliminar Sobre El Alivio de Las Tensiones de Crecimiento En Madera de Eucalyptus Nitens. In Proceedings of the IX Reunión y I Congreso Iberoamericano de Investigación y Desarrollo de Productos Forestales, Concepción, Chile, 18–20 October 2000. [Google Scholar]
  26. Rozas, C.; Morales, M. Estudio Preliminar Sobre Sistemas de Aserrado Para El Alivio de Tensiones de Crecimiento En Eucalyptus Nitens. Taller Sobre Tecnología de La Madera. In Proceedings of the Taller Sobre Tecnología de la Madera, Cartagena de Indias, Colombia, 26–31 March 2001. [Google Scholar]
  27. Lima, J.; Trugilho, P.; Rosado, S.; Cruz, C. Deformações Residuais Longitudinais Decorrentes de Tensões de Crescimento Em Eucaliptos e Suas Associações Com Outras Propriedades. Árvore 2004, 28, 107–116. [Google Scholar] [CrossRef]
  28. Caniza, F. Variación de Las Tensiones de Crecimiento En Tres Clones de Eucalyptus Grandis Según El Estado de Competencia Individual. In Proceedings of the XXII Jornada Forestales de Entre Ríos, Concordia, Argentina, 25–26 October 2007. [Google Scholar]
  29. Calonego, F.; Severo, E. Efeito Da Vaporização de Toras Na Redução Dos Defeitos Associados a Tensões de Crescimento de Eucalyptus Grandis. Cienc. Florest. 2005, 15, 431–440. [Google Scholar] [CrossRef]
  30. Valdés, R. Determinación de Tensiones de Crecimiento de Eucalyptus Nitens (Deane & Maiden) Mediante Un Método No Destructivo. Ph.D. Thesis, Universidad de Talca, Talca, Chile, 2004. [Google Scholar]
  31. Trugilho, P.; Souza, M.; Lima, J.; Rosado, S.; Mendes, L.; Mori, F.; Silva, J. Deformação Residual Longitudinal e Propriedades Da Madeira Em Clones de Eucalyptus. In Proceedings of the Encontro Brasileiro em Madeiras e em Estruturas de Madeira, Cuiabá, Brasil, 27–29 July 2004; p. 12. [Google Scholar]
  32. Yang, J.L.; Baillères, H.; Okuyama, T.; Muneri, A.; Downes, G. Measurement Methods for Longitudinal Surface Strain in Trees: A Review. Aust. For. 2005, 68, 34–43. [Google Scholar] [CrossRef]
  33. Gomes, A. Avaliação das Características da Madeira e da Polpa de Eucalyptus Mediante a Aplicação de Métodos Não Destrutivos Na Árvore Viva. Master’s Thesis, Universidad Federal de Lavras, Lavras, Brasil, 2007. [Google Scholar]
  34. Gonçalves, M. Correlações da Altura e Diâmetro Com Tensões de Crescimento em Árvores de Eucalyptus Citriodora Hook e Eucalyptus Urophylla. T. Blake. Bachelor’s Thesis, Universidad Federal Rural de Rio de Janeiro, Rio de Janeiro, Brasil, 2007. [Google Scholar]
  35. Cardoso, J.; Trugilho, P.; Lima, J.; Rosado, S. Efeito Dos Tratamentos Silviculturais Sobre a Deformação Residual Longitudinal Em Clones de Eucalyptus. Sci. For. 2007, 75, 77–84. [Google Scholar]
  36. Valencia, J. Application of Nondestructive Evaluation Techniques to the Prediction of Sawlog Quality of Eucalyptus Nitens. Ph.D. Thesis, University of Tasmania, Tasmania, Australia, 2008. [Google Scholar]
  37. Burgos, R. Estudio Preliminar Sobre el Efecto de La Inmersión en Agua Sobre la Liberación de las Tensiones de Crecimiento en Trozas de Eucalyptus Nitens. Bachelor’s Thesis, Universidad del Bío-Bío, Concepción, Chile, 2009. [Google Scholar]
  38. Kübler, H. Die Ursache Der Wachstumsspannungen Und Die Spannungen Quer Zur Faserrichtung. Holz Als Roh-Und Werkst. 1959, 9, 15–24. [Google Scholar]
  39. García, J. Técnias de Desdobro de Eucalipto. In Proceedings of the Seminário Internacional de Utilização da Madeira de Eucalipto para Serraria, Piracicaba, Brasil, 5–6 April 1995. [Google Scholar]
  40. Mutizabal, A. Comportamiento de Tensiones de Crecimiento en Tres Procedencias de Eucalyptus Nitens (Deane et Maiden) Maiden, Región del Bío Bío. Bachelor’s Thesis, Universidad Austral de Chile, Valdivia, Chile, 2008. [Google Scholar]
  41. Riquelme, T. Efecto de Las Tensiones de Crecimiento Sobre el Aprovechamiento del Pallet Seco en Trozas de Eucalyptus Nitens (Deane et Maiden) Maiden. Bachelor’s Thesis, Universidad Austral de Chile, Valdivia, Chile, 2011. [Google Scholar]
  42. INN NCh. 992; Madera—Defectos a Considerar en la Clasificación, Terminología y Métodos de Medición. Instituto Nacional de Normalización: Santiago, Chile, 5–6 April 1986.
  43. INN NCh. 993Madera—Procedimientos y Cristerios de Evaluación Para Clasificación; Instituto Nacional de Normalización: Santiago, Chile, 1972.
  44. INN Nch. 973; Madera—Determinación de las Propiedades Mecánicas—Ensayos de Compresión Paralela a las Fibras. Instituto Nacional de Normalización: Santiago, Chile, 1986.
  45. INN NCh. 171/2Madera—Parte 2: Determinación de la Densidad; Instituto Nacional de Normalización: Santiago, Chile, 1982.
  46. INN NCh. 176/1Madera—Parte 1: Determinación de Humedad; Instituto Nacional de Normalización: Santiago, Chile, 1984.
  47. Garay, M. Presecado Industrial de Eucalyptus. Bachelor’s Thesis, Universidad del Bío Bío, Concepción, Chile, 1991. [Google Scholar]
  48. Venturino, A. Secado Solar de Eucalyptus Colorado; LATU: Montevideo, Uruguay, 2005. [Google Scholar]
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Figure 1. (a) Logs immersed in water (b) untreated logs.
Figure 1. (a) Logs immersed in water (b) untreated logs.
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Figure 2. Measurement of the peripheral longitudinal strains in logs immersed in water. (a): rectangular window; (b): nails (distance: 45 mm); (c): Extensometer (d): Extensometer and a 20 mm-diameter drill bit.
Figure 2. Measurement of the peripheral longitudinal strains in logs immersed in water. (a): rectangular window; (b): nails (distance: 45 mm); (c): Extensometer (d): Extensometer and a 20 mm-diameter drill bit.
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Figure 3. Average values of PLS. (a): Untreated logs and (b): logs immersed in water. Where: PLS (1–2): Peripheral longitudinal strain, standing trees. PLSv (3–4): Peripheral longitudinal strain, after felling. PLSi (3–4): Peripheral longitudinal strain after water immersion. TB: Low stress. TM: Medium stress. TA: High stress.
Figure 3. Average values of PLS. (a): Untreated logs and (b): logs immersed in water. Where: PLS (1–2): Peripheral longitudinal strain, standing trees. PLSv (3–4): Peripheral longitudinal strain, after felling. PLSi (3–4): Peripheral longitudinal strain after water immersion. TB: Low stress. TM: Medium stress. TA: High stress.
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Figure 4. Variation of deflection in sawn lumber according to warping (a): without water treatment. and (b): immersed in water.
Figure 4. Variation of deflection in sawn lumber according to warping (a): without water treatment. and (b): immersed in water.
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Figure 5. End splitting index variation along the sawn lumber in the radial direction. (a): before and (b): after air-drying. w/o water: Without water; w/water: with water.
Figure 5. End splitting index variation along the sawn lumber in the radial direction. (a): before and (b): after air-drying. w/o water: Without water; w/water: with water.
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Figure 6. Growth stresses variation in the radial direction according to Kübler’s model [38]. (a): No water treatment (b): Immersed in water.
Figure 6. Growth stresses variation in the radial direction according to Kübler’s model [38]. (a): No water treatment (b): Immersed in water.
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Figure 7. Growth stress variations in the radial direction, according to García’s model [39]. (a): No water treatment and (b): Immersed in water.
Figure 7. Growth stress variations in the radial direction, according to García’s model [39]. (a): No water treatment and (b): Immersed in water.
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Figure 8. Growth stresses variation in the radial direction according to the equation determined in this study. (a): No water treatment and (b): Immersed in water.
Figure 8. Growth stresses variation in the radial direction according to the equation determined in this study. (a): No water treatment and (b): Immersed in water.
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Table
Table 1. Levels of peripheral longitudinal strains measured on the standing trees.
Table 1. Levels of peripheral longitudinal strains measured on the standing trees.
StressRange of PLS (mm)
Low0.0000.110
Medium0.1110.141
High0.1420.507
PLS: Peripheral longitudinal strains.
Table
Table 2. Quantification of warping according to the Chilean Standard NCh993 [43].
Table 2. Quantification of warping according to the Chilean Standard NCh993 [43].
Level/TwistingBowingCrooking
ClassificationLWULLWULLWUL
Level A8 (11%)6 (8%)9 (12%)3 (4%)6 (8%)2 (3%)
Level B54 (73%)14 (19%)58 (78%)59 (79%)25 (34%)20 (27%)
Level C6 (8%)28 (37%)7 (9%)13 (17%)24 (32%)11 (15%)
Level D6 (8%)27 (36%)0 (0%)0 (0%)11 (15%)18 (24%)
Out of the
standard		0 (0%)0 (0%)0 (0%)0 (0%)8 (11%)24 (32%)
Total74 (100%)75 (100%)74 (100%)75 (100%)74 (100%)75 (100%)
LW: Logs immersed in water. UL: Untreated logs. Values in parenthesis are the percentage of warping evaluated at each level.
Table
Table 3. End-splitting in boards.
Table 3. End-splitting in boards.
BoardsStressBoard End Splitting
No Splittingone EndBoth EndsNumber of Boards
BWLow96924
Medium191626
High232025
Total12 (16%)18 (24%)45 (60%)75
UBLow721221
Medium341724
High382031
Total13 (17%)14 (18%)49 (65%)76
BW: Boards immersed in water. UB: Untreated boards. Values in parentheses represent the total percentage of end-splitting in boards.
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Rozas, C.; Burgos, R.; Opazo, A.; Moreno, P.; Erazo, O.; Lasserre, J.P. Distribution of Growth Stresses in Eucalyptus nitens Maiden Logs Immersed in Water. Forests 2023, 14, 1517. https://doi.org/10.3390/f14081517

AMA Style

Rozas C, Burgos R, Opazo A, Moreno P, Erazo O, Lasserre JP. Distribution of Growth Stresses in Eucalyptus nitens Maiden Logs Immersed in Water. Forests. 2023; 14(8):1517. https://doi.org/10.3390/f14081517

Chicago/Turabian Style

Rozas, Carlos, Ricardo Burgos, Alexander Opazo, Pablo Moreno, Oswaldo Erazo, and Jean Pierre Lasserre. 2023. "Distribution of Growth Stresses in Eucalyptus nitens Maiden Logs Immersed in Water" Forests 14, no. 8: 1517. https://doi.org/10.3390/f14081517

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