School of Agriculture, Food and Ecosystem Sciences - Research Publications
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ItemNo Preview AvailableWood Permeability Assessment of Young Teak (Tectona grandis L.f.)(Masyarakat Peneliti Kayu Indonesia, 2021-01-26)Wood properties of young teak (Tectona grandis L.f.) is inferior, and then preservative treatment is one possible solution to enhance its service life. The uptake and movement of preservatives through wood cell structure is directly connected to the wood permeability. There are two simple methods to identify wood permeability: water soaking and bubble test methods. This paper assesses the young teak permeability by water soaking and bubble test methods. The assessment was conducted into five cm thick young-teak discs by soaking in the red-dye water and blowing air into the discs which had been coated with soap. Results show that the heartwood is less permeable than sapwood. Red-dye penetrates almost 100% of the sapwood area, and the red-dye did not penetrate in the heartwood. Red-dye only penetrates in the cracked heartwood through the void volume in the cracking heartwood. There is a transition zone between sapwood and heartwood, and it is refractory. Bubble test with air pressure from compressor could open the air-pathway in the heartwood and sapwood of young-teak discs taken from Bogor. The bubble test result of young-teak discs from Madiun showed air-pathway only in the sapwood, but heartwood. The air pressure is not capable of moving the vapour through the wood cell. It indicates that the heartwood of young-teak from Madiun is less permeable and less possibility for pressure treatment.
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ItemMarket Preference of Wood Characteristics and Properties of Plantation Grown Teak (Tectona grandis Linn.F) in Laos(FORMATH RESEARCH GROUP, 2021)
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ItemAn investigation on peeling recovery and quality of senile plantation-grown rubber trees in Laos(Springer (part of Springer Nature), 2020)The study assessed the peeling potential of rubber trees past the prime latex-producing age when the latex yields become non-economical. Fifteen 25-year-old plantation-grown trees were harvested and peeled using spindleless lathe technology. Following peeling, veneer sheets were measured and graded to determine volume and quality recoveries. Relationships between billet characteristics and recoveries or quality were examined and a recovery predictive model proposed. Most of the main causes identified for downgrading face veneers were either processing-related issues or drying-induced defects. Thus, a combination of several optimisation techniques could annihilate most of the main causes of downgrading veneer, potentially leading to a substantial proportion of higher-quality veneers typically used where surface decorative appearance is a primary consideration. The results demonstrated that rubber trees past their latex-producing prime from unthinned and unpruned stands have qualities and desirable traits to potentially produce certain high-value engineered wood products. Senile rubber trees in Laos could represent significant additional revenue to growers and a source of raw material to the industry which, theoretically, could be converted into high-value products if other factors can be overcome.
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ItemTimber Trading and Pricing of Plantation Grown Teak (Tectona grandis Linn.F) in Laos(SPRINGER, 2021-12)The market demand and price of teak in Laos vary broadly and depend on several factors. The aim of this study was to assess timber trading and pricing based on a survey of teak buyers. The research investigated teak trading methods, markets and prices paid for particular timber types and quality grades. Three types of teak timber are commonly sold: 24.7% as standing trees, 39.6% as round logs and 35.7% as square logs. The main wood products produced from plantation teak include joinery products, door and window frames, and furniture (57.9%, 26.3% and 15.8% respectively). The end buyers of teak timber in Laos are sawmillers and wood manufacturer. Teak timbers supplied to end buyers from growers via the local traders account for 49.0%, followed by 41.3% by direct supply from teak growers and 9.7% via the local small sawmillers and wood manufacturers. The price of teak timber varies significantly based on four main factors: timber types, log sizes, log quality (grades) and distance from plantation site to road (for standing trees). The round log price of 250US$/m3, based on both log diameter size (D26-30 cm) and log quality grade (A grade), was much lower than the 321US$/m3 amount paid for the same size of round log (D26-30 cm) based on log diameter alone (no grading price). It can be concluded that there is a need to develop a clear system or standard for teak log grading and pricing in Laos.
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ItemPlaning characteristics of Papua New Guinea timber species from plantations and regrowth forests(SPRINGER, 2020-03)Although Papua New Guinea (PNG) has a rich and diverse forest cover, there is limited information on processing characteristics for plantations and regrowth forests available. Consequently, the PNG timber processing industry is restricted to a few species, producing low-quality products, which limits opportunities for the processors. Sound knowledge of machining characteristics based on some systematic methods has been identified as essential for assessing the ability in processing raw material into appearance products. Therefore, a testing program was conducted to assess the planing characteristics and most common causes for planing degrade of 25 species sourced from the Morobe and West New Britain provinces, PNG. A total of 18 wood species proved to machine very well with more than 90% of assessed boards being graded either “excellent and requiring very light sanding” or “good and requiring light sanding”. Eight species from this group obtained a perfect score, i.e. requiring very light sanding.
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ItemNo Preview AvailableImpact of Forest Plantation Development in Laos: A Dynamic General Equilibrium Analysis(FORMATH RESEARCH GROUP, 2020)
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ItemThe drying performance and post-drying qualities of Eucalyptus saligna exposed to intermittent and continuous drying(Ministry of Environment and Forestry, 2020-04-01)Eucalyptus saligna tends to develop defects during its drying process, thus limiting its use as construction or furniture material. Intermittent drying, which applies non-heating phases between heating phases, has the potential to overcome this issue. This study evaluated the effects of 3 intermittent and 1 continuous schedule on the species’ drying performance and post-drying qualities. The results showed that the boards from all intermittent schedules exhibit significantly slower drying rates (from -9.4x10-3 /hour to -1.57 x10-2 /hour) than those from the continuous schedule (from -5.12 x10-2 /hour to -1.03 x10-2 /hour). The intermittently-dried boards also developed lower collapse depth (1.162-2.032 mm) than the continuously-dried boards (5.12 mm). Nevertheless, applying higher temperature than that used in the continuous schedule, during the heating phase of the intermittent schedule, potentially increased the moisture gradient, residual drying stress, end check length, internal check percentage, and spring depth.
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ItemASSESSMENT OF PHYSICAL AND MECHANICAL PROPERTIES OF PAPUA NEW GUINEA TIMBER SPECIES(UNIV BIO-BIO, 2020-01)A comprehensive testing program has been developed to assess different physical and mechanical properties of 26 commercial and lesser-known PNG species from secondary and plantation forests. The impact of log position in a tree on the mechanical properties has also been assessed to optimize the utilization of timbers along the value chain. The results showed that stiffness and bending strength tend to decrease or remain unchanged along the stem. Shear strength and Janka hardness displayed a similar trend to a lesser extent where the position in the tree had a limited impact on compression strength properties. Thus, segregating based on log position can be of interest where desired mechanical properties and costs associated with segregating justify optimum mechanical properties for the intended end use. The properties of selected species from plantations and regrowth forests were generally lower than those found in the literature for timbers from old-growth forests. The size of specimens tested, the amount and provenance of tested material, and some adaptive traits for tropical tree species are some factors potentially explaining observed differences. However, a comparison with recent studies tends to confirm the overall reduction of physical and mechanical properties when compared with old-growth forests timbers.