Tangential and radial shrinkage variation within trees in sugi (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) cultivars

The transverse shrinkage variation within trees was examined for five sugi cultivars. The within-tree trends of tangential shrinkage (α _T) were different by cultivar, whereas radial shrinkage (α _R) increased from pith to bark in most cultivars. The tangential/radial shrinkage ratio (α _T/α _R) decreased from pith to bark in most cultivars, because the radial variation of α _R was larger than that of α _T. The cultivars showed significant differences among cultivars in α _T, α _R, and α _T/α _R, but the difference among cultivars for α _T/α _R was smaller. The relationships between transverse shrinkage and microfi bril angle (MFA), basic density (BD), tree ring parameters, and modulus of elasticity were examined. The α _T and α _R showed positive relationships with BD, latewood percentage, latewood density, and modulus of elasticity, and negative relationships with MFA and ring width. The relationships with earlywood density were weak. Sugi exhibited variation in transverse shrinkage within stem and among cultivars, with the variation affected by MFA, density, and tree ring parameters. Part of this article was presented at the 56th Annual Meeting of the Japan Wood Research Society, Akita, Japan, August 2006, and the 57th Annual Meeting of the Japan Wood Research Society, Hiroshima, Japan, August 2007     

Compressive and tensile properties of a butt-jointed lamination model

A study was undertaken to evaluate the effect of glue application and placement of butt-joints on the compressive and tensile properties in a butt-jointed lamination. The aim was to provide background information for producing butt-jointed, glued, laminated timber. Three butt-jointed lamination models were prepared from spruce-pine-fir (S-P-F) dimension lumber with glued and nonglued butt joints, with different placements of the butt joints in the models. The axial stiffness and strength properties were assessed using both compressive and tensile tests. The results of the study indicated that for the compressive lamination model the application of glue at the butt joint gave more stiffness than the nonglued butt joint. Neither glue application nor placement of the joint had a statistically significant effect on the compressive strength. There were no significant differences between the glued and nonglued butt joint for either tensile strength or stiffness.     

Dyeability of Chemically Treated Wood and its Discoloration by UV-ray Irradiation

INTRODUCTION Wood is far from a stable material. One of the biggest challenges for woodworking is learning to work within the constraints of wood properties. Discoloration of wood directly influences the decorative performance of wood products. Therefore, the degree of color change is a critical factor that determines the utilization area of dyed wood (Sakuragawa Satoshi, 1996). Discoloration has occurred because the wood components and dye molecules are degraded by UV-ray (Kaneko Shin…     

Surface deterioration of wood-flour polypropylene composites by weathering trials

The market for wood-fiber plastic composites (WPCs) is expanding rapidly in many countries including Japan, where WPCs are mainly used for exterior products. In such applications, WPCs undergo undesirable color change, chalking, and shrinkage and swelling, and accordingly there is a need to better understand the mechanisms responsible for the weathering of WPC and develop methods of improving their weathering resistance. In this study, weatherability of WPC was assessed by natural and accelerated weathering trials. Discoloration (whitening) of WPC during exposure was caused by degradation of both wood and plastic. Darker color pigments as additives improved the color stability of WPC; however, chalking on the surfaces still occurred. The color stability of WPC was improved by application of exterior coatings. Preweathering of WPC (before coatings were applied) increased the absorption of coatings by the WPC and had a positive effect on the color stability and prevented chalking of the composites. Parts of this study were presented at the IUFRO XXII World Congress Meeting, Brisbane, August 2005 and the IAWPS 2005, Yokohama, November 2005     

The effect of tractor logging on forest soil compaction and growth ofShorea selanica seedlings in Indonesia

The hardness in soil was investigated in four forest areas in Indonesia after a crawler tractor passed over it several times. The hardness in soil, expressed by bulk density, was measured at various depth and various distances from the main track. Recovery of soil hardness was also examined. The bulk density increased markedly by the first and second pass of the tractor, but did not change after the fifth pass. The bulk density was highest just under the main and the log track, and decreased with an increase in distance from the track (0.5 to 1.5 m). The greatest increase in bulk density was observed at the depth of 0–5 cm. The soil hardness tended to show recovery within 9 years after logging, though not completely. Growth and root penetration of seedlingsShorea selanica decreased with the increase of soil hardness. We considered that the 2 tractor passes that caused bulk density of 1.3 g/cm³ is critical for the growth ofS. selanica’s seedling.     

Energy and carbon dioxide (CO2) balance of logging residues as alternative energy resources: system analysis based on the method of a life cycle inventory (LCI) analysis

Using the method of a life cycle inventory (LCI) analysis, the energy balance and the carbon dioxide (CO₂) emission of logging residues from Japanese conventional forestry as alternative energy resources were analyzed over the entire life cycle of the residues. The fuel consumption for forestry machines was measured in field experiments for harvesting and transporting logging residues at forestry operating sites in Japan. In addition, a total audit of energy consumption was undertaken. It involved an assessment of materials, construction, and the repair and maintenance of forestry machines as well as the costs associated with an energy-conversion plant. As a result, the ratio of energy output to input was calculated to be 5.69, indicating that the system examined in this study could be feasible as an energy production system. The CO₂ emission per MWh_e (e: electricity) of the biomass-fired power generation plant was calculated to be 61.8kgCO₂/MWh_e, while that of coal-fired power generation plants in Japan is 960kgCO₂/MWh_e. Therefore, the reduction in the amount of CO₂ emission that would result from replacing coal with biomass for power generation by as much as 3.0 million dry-t/year of logging residues in Japan was estimated to be 1.66 million tCO₂/year, corresponding to 0.142% of the national CO₂ emission. This study provides evidence that Japan could reduce its domestic CO₂ emission by using logging residues as alternative energy resources.     

Growth stimulation of juvenile abalone <Emphasis Type="Italic">Haliotis discus hannai</Emphasis> by feeding with salmon growth hormone in sodium alginate gel

We examined the ability of salmon growth hormone (sGH) in sodium alginate (SA) gel to accelerate the somatic growth of juvenile abalone, Haliotis discus hannai, by feeding. After the feeding of sGH at 50 μg or 100 μg in 350 mg SA gel, immunoreactivity to sGH in body fluid was maximal after 12 h, and was still detectable at 24 h. No immunoreactivity was observed in the control group. Following the feeding of sGH at 0.5 mg or 5 mg/8 g of SA gel at 7- and 14-day intervals, there was a greater increase in shell length and body weight than in the control. In abalone, sGH can be transported from food into the circulatory system and subsequently improve somatic growth.     

Growth variability of Pacific saury Cololabis saira larvae under contrasting environments across the Kuroshio axis: survival potential of minority versus majority

Growth variability was examined for Pacific saury Cololabis saira larvae under contrasting environments across the Kuroshio axis, based on samples collected during the winter spawning season in 2013 and 2014. The growth rate index (residual of the otolith marginal 3‐day mean increment width from the linear regression on knob length) of larvae was compared among three areas: the inshore side of the Kuroshio axis, the Kuroshio axis, and the offshore side of the Kuroshio axis in relation to sea surface temperature (SST), salinity (SSS) and chlorophyll‐a (CHL) concentration. The larvae were more densely distributed in the Kuroshio axis and offshore areas of higher temperature and salinity and lower chlorophyll‐a concentration than in the inshore areas of lower temperature and salinity and higher chlorophyll‐a concentration. No marked differences in the growth rate index were found among the three areas, even though the larvae in the inshore areas showed slightly higher growth rates in 2013. Despite the broad ranges of environmental factors, no clear relationship between the growth rate index and any environmental factor was detected. The survival potential of Pacific saury larvae was considered to be at least comparable under contrasting environments across the Kuroshio axis. Such a geographical homogeneity is concluded to be attributable to compensable effects of physical and biological factors. We hypothesize that the minority under physically‐unfavorable but biologically‐favorable conditions on the inshore side of the Kuroshio axis could survive equally well as the majority under physically‐favorable but biologically‐unfavorable conditions around the Kuroshio axis and on the offshore side of the Kuroshio axis.     

A transdisciplinary research of coastal fisheries co-management: the case of the hairtail <Emphasis Type="Italic">Trichiurus japonicus</Emphasis> trolling line fishery around the Bungo Channel,Japan

Under the coastal fisheries co-management regime in Japan, local fishers play important roles in deciding on and implementing local management measures. Therefore, using the case study of a hairtail trolling line fishery, we conducted a transdisciplinary research with fishers, processors, government officers, etc. Taking social and biological factors into account, we defined management criteria and targets (resource, economic, human community, and local food culture) in collaboration with local fishers. We chartered local fishing vessels to determine parameters that were easily understood by local fishers. We established a local consultative committee comprising fishers, processors, and distributors, and developed a fish distribution strategy to nurture the local hairtail food culture. The integrated effects of various management scenarios were evaluated by the operating model. We found that co-ordinated management by both the trolling line fishery and purse seiners in the neighbouring prefecture was required to achieve targets. Two realistic scenarios are recommended: a conservative scenario that could achieve targets even with few strong year classes, and an adaptive scenario that protects strong year classes, but relies on a higher frequency of these. We shared these results with the local fishers and government officers, which led to actual improvements in management measures.     

Seasonal patterns of downstream movement in partially migratory stream‐dwelling Dolly Varden

Migration is a common behaviour among salmonids, but not all individuals within a population migrate, instead becoming residents and remaining in their natal streams. This phenomenon, known as “partial migration,” is well studied among sea‐run and lake‐run populations; however, the lower migratory benefits and costs for mainstem‐run individuals question whether the same mechanisms can be applied for stream‐dwelling salmonids. In this study, we investigated main stem‐run timing and body condition of partially migratory stream‐dwelling Dolly Varden charr (Salvelinus malma) in the Shiisorapuchi River in central Hokkaido, Japan. Based on commonly observed patterns in sea‐run and lake‐run salmonids, we predicted that migration would occur during spring and consist predominantly of age 1 +  females with some small subordinate males. Traps were placed at the mouths of two small tributaries along the Shiisorapuchi River periodically from May to December 2015. Adipose fin samples were taken for DNA to sex the individuals. Consistent to initial predictions, downstream movement occurs only once in the spring, dominated by age‐1 +  females. Trapped fishes (presumed migrants) were slightly longer but slimmer compared to the fish caught in the tributaries (presumed resident), which may be equivalent to smolts in anadromous populations. Regardless of migratory habitat, mechanisms driving partial migration in salmonids may be the same as long as production between natal stream and feeding habitats is significantly different.