WOOD RESEARCH Volume 70, Number 4, 2025
DWI SUKMA RINI, IKUMI NEZU, AGUS NGADIANTO, DENNY IRAWATI, JYUNICHI OHSHIMA, SHINSO YOKOTA, and FUTOSHI ISHIGURI

DECAY RESISTANCE OF THREE BAMBOO SPECIES NATURALLY GROWING IN LOMBOK ISLAND, INDONESIA

Culms of three bamboo species, Bambusa vulgaris, B. maculata, and Gigantochloa atter, collected from four natural stands in Lombok Island, Indonesia, were decayed by a white-rot fungus, Trametes versicolor, for 90 days. The obtained data were analysed by a mixed-effect model with a random effect of the sites to evaluate the geographic variations of decay resistance of the culms. Mean mass loss values were 16.3% for B. vulgaris, 20.2% for B. maculata, and 13.8% for G. atter. No significant difference in mass loss was found among the three species. Mass loss was positively correlated with amounts of hot-water extracts and organic solvent extracts in B. vulgaris, and with amounts of hot-water extracts and 1% NaOH extracts in B. maculata. As a result of mixed-effect modelling, the variance component ratio of the sites ranged from about 10 to 30%, suggesting that geographic variation was recognized in the culm decay resistance.

WOOD RESEARCH Volume 69, Number 3, 2024
SENDER ALTANGEREL, IKUMI NEZU, JYUNICHI OHSHIMA, SHINSO YOKOTA, and FUTOSHI ISHIGURI

CHANGES IN WOOD QUALITY OF BETULA ERMANII LOGS BY HEATING TREATMENT

Logs of Betula ermaniiCham. were heated at a temperature inside the logs of 80°C for different heating durations of 0, 20, 40, and 60 h using a laboratory oven. After heating treatment, several wood qualities were examined, including residual stresses, moisture content, wood color, and physical and mechanical properties. The effects of the heating treatment duration on wood quality were analyzed using linear mixed-effect modeling. The developed models revealed that heating treatment affected residual stresses and wood color but not mechanical properties. The obtained results also suggest that a heating treatment duration of 20 h is sufficient to reduce residual stresses in B. ermaniilogs without reducing the physical and mechanical properties of wood

WOOD RESEARCH Volume 67, Number 1, 2022
Murzabyek Sarkhad, FUTOSHI ISHIGURI, IKUMI NEZU, Bayasaa Tumenjargal, Bayartsetseg Baasan, Ganbaatar Chultem, JYUNICHI OHSHIMA, Naoto Habu, and SHINSO YOKOTA

Wood chemical components and decay resistance of four common mongolian softwoods

To utilize wood resources in Mongolia, amounts of wood chemical components (hot-water extracts, 1% NaOH extracts, ethanol-toluene extracts, holocellulose, -, -, and -cellulose, Klason lignin, and ash) were determined in four common Mongolian softwoods, Pinus sylvestris, Pinus sibirica, Picea obovata, and Larix sibirica. In addition, decay resistance of heartwood was evaluated against a white-rot fungus Trametes versicolor, and a brown-rot fungus Formitopsis palustris. Among the four species, heartwood of Larix sibirica was chemically characterized by higher amounts of hot-water and 1% NaOH extracts, and lower amounts of holocellulose and Klason lignin. These characteristics may be related to the presence of arabinogalactan which is easily extracted with cold water. Mean mass loss in each softwood ranged from 6.9% to 28.1% in white-rot fungus, and from 24.8% to 48.3% in brown-rot fungus. Among four species, Pinus sibirica showed the highest decay resistance against both fungi. By the linear mixed-effects model analysis, negative relationships were found between mass loss and amounts of extracts in heartwood, suggesting that heartwood having larger amounts of extracts showed higher natural decay durability.