Wood Quality Evaluation and Tree Improvement Methods for Eucalyptus Pellita in Borneo

Yani Japarudin

doi:10.25907/00710

Research Highlight: This study was designed to characterise the utilisation potential of Eucalyptus pellita F. Muell. as a candidate species for commercial plantation deployment in Malaysian Borneo. This study evaluated the current standing resource of E. pellita and characterised the species in the context of solid wood end-use. The knowledge generated has been used to inform selection of germplasm from individuals and families within breeding programs. Background and objective: The Sabah timber industry and more broadly, South-east Asia has been heavily dependent on log supply from natural-growth mixed tropical hardwoods. The realization that natural forests may not be able to sustain and supply industrial requirements has led to the widespread development of tree plantations to address the projected shortfall. The increased financial inputs required to do this means there is a requirement to maintain the profitability of the tree plantation sector through research and maintaining best practice, but there are currently many knowledge gaps. Therefore, there is a need to gain a wider perspective of potential plantation species to realign the timber processing industry needs to be able to utilise the resource obtained from well managed plantations. The general objective of this study is to deliver wood quality improvements through tree breeding programs for sustainable and profitable industrial tree plantation. Material and methods: Three key aspects of this study have involved; (1) comparative assessment of the growth productivity of E. pellita with respect to alternate exotic plantation species and domestic tropical hardwood species, (2) assessment of the recovery potential for solid wood and veneer production along with assessment of key wood mechanical properties (strength, stiffness and compression), (3) Non-destructive techniques developed in previous studies and validated in this study were then applied to genetic breeding trials to provide phenotypic data for analysis of end-use trait properties. Result: The description of solid wood characteristics is discussed and factors limiting the efficiency for sawn timber and peeling were revealed. Total recovery of solid wood and peeling operations was undertaken and high value appearance-grade veneer recovered from unpruned older stands (> 7 years). Findings demonstrate the need for an appropriate silviculture management and downstream processing strategy to optimise the quality and quantity of veneer and sawn board production. This study had provided a basis for better understanding of longitudinal and radial variation of strength and stiffness in E. pellita grown in the wet tropics. Mechanical stiffness, bending strength and compressive strength are sufficiently high at all radial and longitudinal positions within the stem and across the age and diameter classes examined, so that E. pellita would meet specification for structural use as defined in the Malaysian Grading Rules. Along with the intensive mechanical testing of thousands of small clears, non-destructive methods for predicting mechanical wood properties were validated, namely acoustic wave velocity and near infrared (NIR) spectroscopy for wood stiffness prediction on standing trees and logs. Dynamic MOE calculated from standing tree acoustic velocity showed good correlation with the mean MOE from static bending for the wood in the butt log, representing the location where standing tree acoustic velocity measurements were obtained. This study has identified and quantified traits that can be intensively assessed and then drawn together in a rapid evaluation system suitable for screening thousands of trees in large-scale tree breeding populations. Conclusion: Eucalyptus pellita is a suitable species for deployment and support the intended use of this species for solid wood utilisation in Borneo. The results indicate the potential to produce high-value products with high mechanical performance to meet structural specifications. The methodological approach using the non-destructive technologies provides the tools to explore opportunities to integrate selection processes in open pollinated breeding populations to improve the important wood quality traits in future generations to produce improved germplasm for deployment in Borneo.

Wood Quality Evaluation and Tree Improvement Methods for Eucalyptus Pellita in Borneo

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