Mangrove forest productivity and biomass accumulation in Hinchinbrook Channel,Australia

Data on stand structure and rates of photosynthesis were used to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests in Hinchinbrook Channel, Australia. Total annual canopy net carbon fixation was estimated to be about 29tCha–1yr–1. This equates to about 204,000tCyr–1 for all mangrove forests in Hinchinbrook Channel. Of this, only about 12% was stored as living plant biomass. Although it is not yet possible to present a robust carbon balance for mangrove trees, the remainder is presumably lost through plant respiration, litter fall, root turnover and exudation of organic compounds from roots.     

Biological performance of wood-based composites treated with a formulation of 3-iodo-2-propynyl butylcarbamate and silafluofen using supercritical carbon dioxide

Wood-based composites (medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board) treated with a mixture formulation of 3-iodo-2-propynyl butylcarbamate (IPBC) and silafluofen using supercritical carbon dioxide as a carrier solvent were evaluated for their resistance to biological attack in a laboratory study. The formulation was pre-pared by mixing 10g of IPBC and 1g of silafluofen in ethanol solution (20ml). Treatments were conducted at 35°C/7.85MPa, 35°C/9.81MPa, and 55°C/11.77MPa with the direct introduction of 20ml of the formulation into the treatment vessel with a capacity of ca. 2000ml at a rate of 2ml/min. Laboratory tests indicated that the treatment conditions used significantly enhanced the resistance of the treated wood-based composites against fungal and termite attacks. Because no significant difference in efficacy against both biodegrading agents was noticed regardless of the treatment conditions, the treatment at 35°C/7.85MPa was thought to be the most economical in terms of energy consumption and performance of treated materials. However, the amount of biocides in a formulation must be carefully selected in accordance with the required treatment condition to ensure satisfactory performance of the treated wood-based composites against any biological agent.     

Mangrove structure,litter and macroalgal productivity in a northern‐most forest of Florida

Rhizophora mangle L. dominated 10 overwash islands within Tampa Bay forming the northernmost mangrove forests on the west coast of Florida. The mean number of trees and basal area were 5040 trees ha^-1 and 20.5m²ha^-1, respectively. Basal areas ranged from 1.1 (Avicennia germinans (L.) Stern), to 2.6m²ha^-1 (Laguncularia racemosa Gaertner), to 16.8 (R. mangle). Cockroach Bay mangroves are small (5.8–7.0m tall) versus coastal forests of south Florida and the Caribbean. Total litter production for a 12 month period was maximal in September for fringing (7.4gdwtm^-2d^-1) and interior (8.7gdwtm^-2d^-1) areas with the two zones not being significantly different. Average litter fall (3.1gdwtm^-2d^-1) was similar to more tropical Caribbean mangals. Leaves accounted for 68 of the litter and reproductive material for 6, being similar to tropical riverine and overwash marine angiosperm communities on the Mexican coast. Although mangrove forests in Tampa Bay are small in stature and experience cold damage and occasional frosts, their litter fall is similar in biomass to that of more tropical mangals. However, their reproductive output is low based on litter fall versus more tropical mangals suggesting that the northern extension is less than optimum. Macroalgal diversity was low (10 species) as compared to Caribbean mangals. Macroalgal turf (0.8gCm^-2d^-1) and epiphyte communities of A.germinans pneumatophores (2.7gCm^-2d^-1) have productivity levels that are equal to or greater than those of Caribbean mangals.     

Sapling architecture and growth in the co-occurring species Castanopsis cuspidata and Quercus glauca in a secondary forest in western Japan

This study quantitatively compared the sapling (height 62–289cm) architecture and growth of Castanopsis cuspidata and Quercus glauca, both of which are major components in the temperate zone of western Japan, under shaded light conditions in secondary forest. When the sapling architectures were compared at the same support mass (trunk + branch mass), C. cuspidata had a larger crown area but a smaller height gain than did Q. glauca owing to the allocation of more biomass to lateral branches in C. cuspidata. The above-ground relative growth rate (RGR) of C. cuspidata (0.442gg^–1 year^–1) was nearly twice that of Q. glauca (0.256gg^–1year^–1), primarily as a result of a greater total leaf area per above-ground biomass (LAR) in C. cuspidata (56cm²g^–1) as compared to Q. glauca (33cm²g^–1). Because it has a disadvantage in height gain, related to its allocation pattern of biomass, C. cuspidata realized the same height growth (RGR_H) as Q. glauca, despite the large biomass production. The great potential for photosynthesis in C. cuspidata, which results from its vigorous lateral spreading, is presumed to give it a long-term advantage over Q. glauca in the shaded forest understory. Q. glauca invests preferentially in trunk biomass, possibly giving it an advantage in sunny sites as opposed to a shaded forest understory.     

Sediment accretion and variability of sedimentological characteristics of a tropical estuarine mangrove: Kemaman, Terengganu, Malaysia

This paper reports on a study of accretion rate and sedimentological variability in a estuarine mangrove swamp. One hundred and sixteen stations were monitored for 2 years. In addition, surface sediment samples were collected at 52 stations during the months of May, June and July (1994) to represent the nonmonsoon sediments and November, December (1994) and January (1995) to represent the monsoon sediments. Results show that the accretion rate for the first year was 1.46±0.13cm/yr and 0.66±0.04cm/yr for the second year thus making the average accretion for the 2 years period to be 1.06cm/yr. The average accretion rate for the monsoon season (0.26 ± 0.04cm/month) was found to be significantly higher than the nonmonsoon season (0.12 ± 0.03cm/month). Nevertheless, the same is not true for the surface sediment characteristics. The sedimentological characteristics between the monsoon and the nonmonsoon sediments were not significantly different.     

Physiological and psychological responses to a heavy floor-impact sound generated by dropping an automobile tire in a wooden house

We investigated the physiological and psychological responses of ten healthy male volunteers to a single heavy floor-impact sound generated by dropping an automobile tire from heights of 50, 100, and 150cm in a wooden house. Blood pressure and peripheral blood flow were measured simultaneously, and sensory evaluation was conducted using the semantic differential method. The results obtained were as follows: (1) the systolic blood pressure increased and the peripheral blood flow decreased when the subjects heard the heavy floor-impact sound; (2) the heavy floor-impact sound caused the subjects to feel uncomfortable, but there was no significant change in sharp and monotonous feelings; and (3) for the heavy floor-impact sound for 100cm and that for 150cm, the subjects showed no difference in comfortable feeling, but we detected differences in the variations of both the systolic blood pressure and the peripheral blood flow.Part of this research was presented at the 48th Annual Meeting of the Japan Wood Research Society, Shizuoka, April 1998.     

Root morphology and nutritional status of Japanese red cedar saplings subjected to in situ levels of aluminum in forest soil solution

There is little information on the effects of in situ levels of aluminum (Al) in the forest soil solution on the root morphology of Japanese red cedar (Cryptomeria japonica D. Don). We evaluated whether morphological and nutritional changes in the white roots of Japanese red cedar saplings grown in glass-bead culture for 18 weeks occurred in response to Al solutions at five concentrations: 0 (control), 0.05, 0.1, 0.5, and 1.0mM. Branching white roots treated with 0.5 or 1.0mM Al had some stunted, brown, thickened tips. Their mean lengths were significantly shorter than those of roots treated with 0.05 or 0.1mM Al. The maximum diameters of white roots treated with 0.5 or 1.0mM Al were significantly larger than those of the control. Treatment with 0.5 or 1.0mM Al reduced the concentrations of Ca and Mg in the white roots and increased the concentration of Al compared with the control. These results indicate that between 0.1 and 0.5mM Al, a drastic change occurs in the effects of Al on the morphology and nutritional status of white roots of Japanese red cedar saplings, and suggest that the Al levels in Japanese forest soils may induce morphological changes in the white roots.     

Nitrogen use by <Emphasis Type="Italic">Pinus densiflora</Emphasis> trees growing on a Mt. Fuji lava flow

To quantify the nitrogen (N) use by Pinus densiflora trees growing on an infertile lava surface, N pools, N requirement and N uptake through fine roots and N deposition from the atmosphere were estimated. The N requirement and the N uptake of fine roots were 55.5kgNha^–1year^–1 and 39.7kgNha^–1, respectively. Thus, the ratio of N uptake to N requirement of the fine roots was 71.5%. Including fine-root contribution, the total N requirement of the P. densiflora trees was 98.6kgNha^–1year^–1, and the total N uptake was 64.2kgNha^–1year^–1. Thus, the N uptake of the P. densiflora trees was 64.1% of the N requirement, indicating that P. densiflora trees growing on an infertile lava surface obtain some of their N from below-ground organic material layers every year and the contribution of N storage in trees for their growth is not any higher than indicated in previous reports that excluded fine-roots contribution. The wet N deposition of our research forest was only 5.8% of the N requirement of the P. densiflora trees and only 8.9% of the N uptake. Movement of the below-ground organic material layer N concentrations in the F- and L-layers coincides with needle development and fine-root growth, suggesting the possibility that P. densiflora trees extract N from the organic N of those layers for growth.     

Effects of soil solarization on nematodes in Croatia

For the first time soil solarization was investigated in Croatia both in the field and in the greenhouse in 1991, 1992, 1993 and 1994. For two months (July and August), the soil was mulched with transparent polyethylene (PE) sheets of 0.015 or 0.050mm thickness. Soil temperatures at depths of 5, 10 and 20cm were recorded daily. In order to assess nematode population densities, soil samples were analysed before mulching and at the end of the mulching treatment. The results of these experiments showed that soil solarization drastically reduced the population of plant-parasitic nematodes (Meloidogyne, Pratylenchus, Paratylenchus, Tylenchus, Tylenchorhynchus spp.) by about 97–100% at a depth of 10cm and 92–97% at a depth of 20cm in the field, while in the greenhouse, the population of plant-parasitic nematodes was reduced by about 89–100% at a depth of 10cm and 98–100% at a depth of 20cm.In the same experiments, the population of saprophytic nematodes in the field was reduced by about 86–90% at a depth of 10cm and 72–89% at a depth of 20cm. In the greenhouse, the population of saprophytic nematodes was reduced by about 87–97% at a depth of 10cm and 87–93% at a depth of 20cm. This data shows that soil solarization was less effective in the control of saprophytic nematodes, which is considered to be an advantage.     

Effects of a nursery CO2 enriched atmosphere on the germination and seedling morphology of two Mediterranean oaks with contrasting leaf habit

The use of an enriched CO₂ atmosphere in tree nurseries has been envisaged as a promising technique to increase productivity and to obtain seedlings with a higher root/shoot ratio, an essential trait to respond to water stress in Mediterranean-type ecosystems. In that framework, we have analyzed the effects of three levels of atmospheric CO₂ concentration (350, 500 and 700ppm) on the germination rate, growth and morphology of seedlings of two Mediterranean oaks used in reforestation programs: the evergreen Quercus ilex L. and the deciduous Quercus cerrioides Wilk. et Costa. CO₂ enrichment increased the germination rate of Q. cerrioides (from 70±7 to 81±3%) while it decreased that of Q. ilex (from 71±10 to 41±12%). Seedlings of both species increased approximately 60% their total biomass in response to CO₂ enrichment but at two different CO₂ concentrations: 500ppm for Q. cerrioides and 700ppm for Q. ilex. This increase in seedlings biomass was entirely due to an augmentation of root biomass. Considering germination and biomass partitioning, an enriched CO₂ atmosphere might not be appropriate for growing Mediterranean evergreen oaks, such as Q. ilex, since it reduces acorn germination and the only gains in root biomass occur at a high concentration (700ppm). On the other hand, a moderate CO₂ enrichment (500ppm) appears as a promising nursery technique to stimulate the germination, growth and root/shoot ratio of deciduous oaks, such as Q. cerrioides.     

Sediment mixing and accumulation in a mangrove ecosystem: evidence from 210Pb, 234Th and 7Be

210Pb, 234Th and 7Be activities were measured to establish sediment accumulation rates, estimate sediment mixing rates, and determine the depth of the sediment mixed layer in the Sepetiba Bay mangrove ecosystem near Rio de Janeiro City, Brazil. Three sediment cores were collected from Enseada das Garças, a typical exposed tidal flat region with a sequence of sedimentary features. The seaward edge of this sequence is a mud flat with the landward portion covered with Spartina alterniflora followed by mangrove vegetation. An additional core was collected on an overwash island near Barra de Guaratiba, which is cover with mangroves without a mud flat or Spartina alterniflora sequence. Sediment accumulation rates were determined to range up to 1.8cm/yr with the Spartina alterniflora having the maximum rate. Mixing rates were estimated for the Spartina alternifloracore at 40cm2/yr based on 210Pb and 7Be from the upper mixed region of the core. The 234Th activity in this core suggested that either mixing or the input of 234Th were not in steady state. The sediment mixed region depth ranged from 4cm to greater than 30cm. At the Enseada das Garças site the mixing depth decreased in the landward direction (i.e. mud flats > 30cm, Spartina alterniflora 11cm, mangroves 4cm). Along with this decrease in sediment mixing depth was a shift from physical to biological mixing. The Barra de Guaratiba core had a sediment mixed layer of 13cm as a result of physical and intense biological activity.     

Changes in the physical and chemical properties of six Japanese softwoods caused by lengthy smoke-heating treatment

The effects of prolonged smoke-heating treatments on wood quality were investigated. Six Japanese softwoods were smoke-heated for 100 and 200h at a temperature of 75° ± 5°C, which was recorded inside the log. After smoke heating, wood quality, including moisture content, amounts of chemical components, relative degree of crystallinity (RDC) of cellulose, and sapwood color were examined. Moisture content decreased as a result of smoke heating, especially in sapwood, leading to a uniform distribution of moisture content within a log. Almost no difference was found in the amounts of chemical components between the control woods and the woods that were smoke-heated for 100h. However, in the wood that was smoke-heated for 200h, the amounts of holocellulose decreased, suggesting that thermal deterioration and/or degradation of hemicelluloses had occurred. We assume that the increase in RDC was caused by smoke heating with the crystallization of cellulose and/or thermal degradation of hemicelluloses. Almost no differences were found in sapwood color between the control woods and the woods that were smoke-heated for 100h. In the wood that was smoke-heated for 200h, however, L*decreased, whereas a* and b* increased. As a result, E*ab, showing the total color change, increased, resulting in a deeper color. These results suggest that thermal degradation of hemicelluloses was caused by smoke heating for over 100h. Therefore, smoke heating of softwood logs using a commercial-scale kiln should not exceed 100h.     

Effect of thawing regime on growth and mortality of frozen-stored Norway spruce container seedlings planted in cold and warm soil

One-year-old frozen-stored Norway spruce (Picea abies (L.) Karst.) container seedlings were planted in a controlled environment providing an air temperature of 22°C and soil temperature of 9±1 or 18±1°C. At planting the root plugs were either frozen or had been thawing for 4 days at 9°C. During a 5-week growing period, in both cold and warm soil the root growth and height growth were less in frozen-planted seedlings than in thawed seedlings. In addition, frozen-planting delayed bud burst and increased mortality. Soil temperature, however, had no effect on bud burst or mortality. Low soil temperature retarded root growth of seedlings thawed before planting but resulted in both retarded root growth and height growth if root plugs were frozen when planted. These results indicate that planting Norway spruce seedlings with frozen root plugs constitutes a considerable risk for successful forest regeneration at soil temperatures normally prevailing in Fennoscandia in spring or early summer especially if the soil is dry at the time of the planting.     

Analysis of current forest operations in the Okumikawa Forestry Area by location and topography

We analyzed current forest operations in Toei, in the Okumikawa Forestry Area, Japan, by examining actual achievement, location, and topography. We considered five basic forest operations conducted by the Forest Owners Association between 1991 and 2000 in a subsidized reforestation and silviculture project: planting, weeding, pruning, cleaning, and thinning. In addition, we considered the road network, including public, forest, and strip roads. The area in which forest operations have been conducted over the past 10 years amounted to less than two-thirds of the area targeted in the Toei Forest Improvement Plan. The mean access distance of the work sites was 164m, which was 52m less than the 10-year average for the whole forest (216m). Forest operations tended to ignore remote forest areas where the topography was steep, due to cost, the logging techniques required, and labor requirements. We determined that the limitations on forest operations in Toei were a 300m access distance, an elevation of 800masl, and a 90% slope. In accessing work sites, the utilization ratios of forest and strip roads were higher than their composition ratios, and public roads were used most. Newly constructed strip roads were used more than forest roads. Based on current forest operations, we calculated the road density and length required to be 7.1m/ha and 79.2km, respectively, with an estimated cost exceeding 720 million yen for new construction.     

Gamma radiation sensitivity of larvae and adults of the red flour beetle, <Emphasis Type="Italic">Tribolium castaneum</Emphasis> Herbst

In this study, the susceptibility of larvae and adults of Tribolium castaneum (Herbst) to gamma radiation was investigated in the laboratory in Turkey. Gamma radiation was applied at 6 dose levels between 20 and 200Gy to 13–15day-old adults and at 5 dose levels between 20 and 180Gy to 18–20day-old larvae of T. castaneum. All experiments were performed in growth chambers maintained at 27±1°C and 70±5% r.h. The larvae proved to be the more susceptible stage, survival to the adult stage being prevented by exposure of the eggs to 100Gy; the adult stage was less susceptible. LD₅₀ and LD₉₉ values were determined as 19,75 and 42,97Gy for larvae and 33,21 and 64,50Gy for adult stage, respectively. It was concluded that 100Gy is the effective dose for both larval and adult stages.     

Porewater dynamics and the formation of iron sulfides in a mangrove ecosystem,Sepetiba Bay,Brazil

Porewater dynamics and the formation of iron sulfides were studied in the Brazilian mangrove. Porewater samples were collected during tidal cycles using in situ equipment and physical–chemical and chemical data were obtained. The advective transport of porewater by tidal currents was found to be more effective between 0 and 5cm depth than below 15cm. The diffusive input of atmospheric oxygen during low tides resulted in oxidation of porewater dissolved sulfides. Thermodynamic considerations identified pyrite as the main iron sulfide forming at this depth, and the amorphous iron hydroxides are probably the main iron source. Below 15cm depth, irregular root distribution underground and benthic faunal bioturbation caused considerable spatial variation in a small scale (20cm). The correlation between alkalinity and total dissolved sulfide suggests that the main pathway for organic matter decomposition is sulfate reduction. Formed in the highly sulfidic diagenetic zone, the dissolved iron went through iron sulfide formation process. Crystalline iron oxides like hematite and magnetite may constitute an important iron source below 15cm, whereas pyrite is still the most probably occurring iron sulfide, according to thermodynamic considerations.     

Die Übertragung des Enationenvirus der Erbse durch verschiedene Morphen der BlattlausartenMacrosiphum euphorbiae (Thomas) undAcyrthosiphon pisum (Harris)

Zusammenfassung Unterschiedliche Vektoreignungen können zwischen Rassen, Morphen und Altersstadien einer Blattlausart auftreten. Es wurden verschiedene Morphen vonMacrosiphum euphorbiae (Thomas) undAcyrthosiphon pisum (Harris) hinsichtlich ihrer Übertragungsfähigkeit für das persistente Enationenvirus der Erbse geprüft. Dabei erwiesen sich ovipare Weibchen und adulte Männchen vonM. euphorbiae als ungeeignete Überträger, während die gleichen Morphen von zweiA. pisum-Populationen die Virose übertrugen. Auch die Fundatrix desA. pisum-BastardsTrifolium pratense rot XSarothamnus scoparius grün übertrug zu einem relativ hohen Prozentsatz. Ovipare Weibchen und Männchen der inaktiven RasseLotus uliginosus gelb konnten keine Infektion bewirken; die persistente Virusübertragungsfähigkeit ist im Falle vonAcyrthosiphon pisum (Harris) offenbar ein genetisch fixiertes Merkmal.

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Summary Different vector abilities may exist between races, morphs and development instars of a given aphid species. Several morphs ofMacrosiphum euphorbiae (Thomas) and ofAcyrthosiphon pisum (Harris) were tested in their transmission ability for the persistent pea enation mosaic virus. Oviparous females and adult males ofM. euphorbiae proved insuitable for transmission, the corresponding morphs of twoA. pisum-populations, however, were successful in transmitting. The fundatrix of theA. pisum hybridTrifolium pratense red xSarothamnus scoparius green transmitted to a relatively high percentage. Oviparous females and males of the inactiv raceLotus uliginosus yellow failed completely in transmitting; in the present case ofA. pisum the transmission character of the persistent virus evidently is genetically fixed.

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Résumé Différentes aptitudes de vecteur peuvent se trouver entre les races, les morphes et les périodes d'âge d'une espèce de pucerons. Différentes morphes deMacrosiphum euphorbiae (Thomas) et deAcyrthosiphon pisum (Harris) ont été examinées en ce qui concerne leurs aptitudes de transmettre le virus persistant du pois(pea enation mosaic). En ce cas les femelles ovipares et les mâles adultes deM. euphorbiae se montraient impropres à la transmission, pendant que les mêmes morphes de deux populations deA. pisum transmettaient la virose. C'était la fondatrice du bâtard deA. pisum Trifolium pratense rouge avecSarothamnus scoparius vert qui transmettait à une pourcentage relativement haute. Les femelles ovipares et les mâles de la race «inactive» deLotus uliginosus jaune ne pouvaient pas effectuer d'infection; en cas deAcyrthosiphon pisum (Harris), l'aptitude persistante à transmettre le virus évidemment est un caractère fixé d'une façon génétique.

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, . Macrosiphum euphorbiae (Thomas) Acyrthosiphon pisum (Harris) peaenation mosaic virus). M. euphorbiae , {A. pisum} . A. pisum-Trifolium pratense Sarothamnus scoparius . «» Lotus uliginosus ; Acrythosiphon pisum (Harris) .

     

Compressive deformation of wood impregnated with low molecular weight phenol formaldehyde (PF) resin I: effects of pressing pressure and pressure holding

The deformation behavior of low molecular weight phenol formaldehyde (PF) resin-impregnated wood under compression in the radial direction was investigated for obtaining high-strength wood at low pressing pressures. Flat-sawn grain Japanese cedar (Cryptomeria japonica) blocks with a density of 0.34g/cm³ were treated with aqueous solution of 20% low molecular weight PF resin resulting in weight gain of 60.8%. Oven-dried specimens were compressed using hot plates fixed to a testing machine. The temperature was 150°C and the pressing speed was 5mm/min. The impregnation of PF resin caused significant softening of the cell walls resulting in collapse at low pressures. The cell wall collapse was strain-dependent and occurred at a strain of 0.05–0.06mm/mm regardless of whether the wood was treated with PF resin. Thus, pressure holding causing creep deformation of the cell walls was also effective in initiating cell wall collapse at low pressure. Utilizing a combination of low molecular weight PF resin impregnation and pressure holding at 2MPa resulted in a density increase of PF resin-treated wood from 0.45 to 1.1g/cm³. At the same time, the Youngs modulus and bending strength increased from 10GPa to 22GPa and 80MPa to 250MPa, respectively. It can be concluded that effective utilization of the collapse region of the cell wall is a desirable method for obtaining high-strength PF resin-impregnated wood at low pressing pressures.     

Canopy cover effects on nitrogen and phosphorus status in understory vegetation in oak and pine stands

The rate of change of leaf mass, N and P levels in understory vegetation at various levels of canopy cover were measured for 2 years following canopy cover manipulations in northern red oak (Quercus rubra L.) and red pine (Pinus resinosa Ait.) stands in northern Lower Michigan, USA. Canopy cover treatments consisted of clearcut, 25% (50% during first sampling year), 75%, and uncut. Leaf mass, and N and P contents were significantly higher in the clearcut treatment than in other canopy cover treatments, except for the 25% treatment in red pine stands. Leaf N concentrations in understory vegetation were also significantly higher in the clearcut (1991, 20.8mgg^–1; 1992, 22.4mgg^–1) than in the uncut treatment (1991, 16.5mgg^–1; 1992, 16.9mgg^–1). Canopy type (northern red oak and red pine) had little influence on understory nutrient status and leaf mass. In addition, fronds of bracken ferns in all canopy cover treatments in both northern red oak and pine stands were a major sink of nutrients in the understory. The results of this study showed that partial canopy removal generally had only a minor impact on understory leaf production and nutrient status compared with clearcuts during the 2-year period following canopy removal.     

Manufacture and properties of low-density binderless particleboard from kenaf core

Low-density binderless particleboards from kenaf core were successfully developed using steam injection pressing. The target board density ranged from 0.10 to 0.30g/cm³, the steam pressure used was 1.0MPa, and the steam treatment times were 7 and 10min. The mechanical properties, dimensional stability, and thermal and sound insulation performances of the boards were investigated. The results showed that the low-density kenaf binderless particleboards had good mechanical properties and dimensional stability relative to their low board densities. The board of 0.20g/cm³ density with a 10-min treatment time produced the following values: modulus of rupture 1.1MPa, modulus of elasticity 0.3GPa, internal bond strength 0.10MPa, thickness swelling in 24h water immersion 6.6%, and water absorption 355%. The thermal conductivity of the low-density kenaf binderless particleboards showed values similar to those of insulation material (i.e., rock wool), and the sound absorption coefficient was high. In addition, the boards are free from formaldehyde emission. Kenaf core appears to be a potential raw material for low-density binderless panels suitable for sound absorption and thermally resistant interior products.Part of this report was presented at the 52th Annual Meeting of the Japan Wood Research Society, Gifu, Japan, April 2002