Effect of major inorganic nutrients on <Emphasis Type="Italic">β</Emphasis>-thujaplicin production in a suspension culture of <Emphasis Type="Italic">Cupressus lusitanica</Emphasis> cells

 The optimum conditions for β-thujaplicin production in a Cupressus lusitanica cell suspension culture were investigated. The conditions required for β-thujaplicin production were clearly different from the conditions for cell growth. The initial phosphate concentration and pH did not affect β-thujaplicin production. A total nitrogen source concentration higher than 3.2 mM suppressed production due to the presence of the ammonium ion. β-Thujaplicin production was observed at 95 mg/l without adding the ammonium ion to the medium. Strict control of major inorganic nutrients was not necessary to produce β-thujaplicin. This finding seems to be favorable for future automated production of β-thujaplicin in commercial cell culture plants.     

Catalytic graphitization of hardwood acetic acid lignin with nickel acetate

 Catalytic graphitization of hardwood acetic acid lignin (HAL) with nickel (II) acetate was investigated regarding the production of highly crystalline carbon. Fusibility, one of the unique characteristics of HAL, was preserved with nickel acetate additions up to 0.3% (as the weight of nickel), although the thermal mobility of HAL was depressed by the addition of nickel acetate. An obvious effect of nickel salt as a catalyst on the development of carbon crystallite from HAL was observed for more than 0.2% addition. The development was found to proceed above 850°C. All the resulting carbons had turbostratic structure, and the apparent crystallite size (L _c) was increased with increasing amounts of catalyst, as determined by X-ray diffraction. Thus, highly crystalline carbon was produced from HAL by catalytic graphitization without compromising the fusibility of HAL by adding a small amount of organic nickel salt. Received: December 17, 2001 / Accepted: March 27, 2002 Present address: Department of Wood and Paper Science, North Carolina State University, NC 27695-8005, USA Part of this paper was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000 Correspondence to:Y. Uraki     

Protective effect of floor cover against soil erosion on steep slopes forested with <Emphasis Type="Italic">Chamaecyparis obtusa</Emphasis> (hinoki) and other species

 We evaluated the protective effects of floor cover against soil erosion in three types of forest located on steep slopes under a humid climate: 22- and 34-year-old Chamaecyparis obtusa (hinoki), 34-year-old Cryptomeria japonica (sugi), and 62-year-old Pinus densiflora (red pine) stands. We measured sediment transport rates (sediment mass passing through one meter of contour width per millimeter of rainfall), using sediment traps, before and after removing floor cover. Raindrop splash erosion was dominant in the experimental stands. Floor cover percentage (FCP) during the preremoval stage varied from 50% to 100% among the four stands, and sediment transport rates ranged from 0.0079 to 1.7 g m⁻¹ mm⁻¹. The rates increased to 1.5–5.6 g m⁻¹ mm⁻¹ immediately after removing floor cover, and remained high throughout the experiment. The presence of physical cover near the ground has a crucial effect on sediment transport on forested slopes. The protective effect ratio (the ratio of the sediment transport rate in a control plot to that in the removal plot) in a young hinoki stand, in which the FCP decreased markedly, was 0.3 at most, which is close to the rate for bare ground. The protective effect ratio in the red pine stand was ≤0.003. We concluded that the protective effect of floor cover in undisturbed forests in Japan differs by over two orders of magnitude, based on comparisons with previous studies. Received: March 11, 2002 / Accepted: August 16, 2002 Present address: Department of Forest Site Environment, Forestry and Forest Products Research Institute, Ibaraki 305-8687 Japan Tel. +81-298-73-3211; Fax +81-298-74-3720 e-mail: miura@affrc.go.jp Present address: Department of Forest Site Environment, Forestry and Forest Products Research Institute, Ibaraki 305-8687 Japan Tel. +81-298-73-3211; Fax +81-298-74-3720 e-mail: miura@affrc.go.jp Acknowledgments This study was supported by the Research Council of the Ministry of Agriculture, Forestry, and Fisheries, of Japan. We thank H. Ujihara, S. Ujihara, and M. Ogasawara in Otoyo, Kochi, who provided the experimental stands used in this study. We also thank K. Hirai, S. Kuramoto, E. Kodani, and the rest of the staff at the Shikoku Research Center, Forestry and Forest Products Research Institute, for their help in conducting the experiments. Correspondence to:S. Miura     

Relaxation mechanism of residual stress inside logs by heat treatment: choosing the heating time and temperature

 Some methods to reduce residual stress inside logs have been reported, although the conditions for stress relaxation are not yet clarified. Our study using precise experiments revealed that residual stress relaxation occurs only when both heat and moisture exist inside the logs. We then determined the heating time and temperature required to relax the residual stress inside the logs. Short air-drying treatments did not relax residual stress even though free water in the logs was greatly reduced. The residual stress of the 33-h 80°C-heated bolts was relaxed, whereas that of the 48-h 70°C-heated bolts was not. As for the influence of treatment time, bolts heated at 100°C were relaxed after 18 h of treatment. The 13-h heated bolts did not show any relaxation. Therefore, residual stress relaxation occurred rapidly owing to the thermomechanical change of the individual wood components comprising the cell wall. The moisture content inside all the bolts was much higher than the fiber saturation point. This is because relaxation occurs only when the heating temperature is maintained above 80°C for a particular duration of treatment. Received: December 12, 2001 / Accepted: February 18, 2002 Present address: Institute for Structural and Engineering Materials, National Institute of Advanced Industrial Sciences and Technology, Independent Administrative Institution, Nagoya 463-8560, Japan Tel. +81-52-736-7320; Fax +81-52-736-7419 e-mail: m.nogi@aist.go.jp Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000 Correspondence to:M. Nogi     

Spatial distribution of sporocarps and the biomass of ectomycorrhizas of <Emphasis Type="Italic">Suillus pictus</Emphasis> in a Korean pine (<Emphasis Type="Italic">Pinus koraiensis</Emphasis>) stand

 Spatial distribution of sporocarps of Suillus pictus A.H. Smith and Thiers was studied in a plot of 6 × 12 m in size established in a stand of Pinus koraiensis Sieb. et Zucc. in Kyoto, Japan for 4 years, and the biomass of mycorrhizas was examined in the last year. S. pictus was dominant in both sporocarp and ectomycorrhizal community in the study plot. The number of S. pictus sporocarps ranged from 0.94 to 1.26 m⁻² (surface area) in the study plot and did not vary very much during the study period. Sporocarps of S. pictus occurred in clumps and the distributions of clumps were generally random. As the spots of sporocarp occurrence changed gradually from year to year, the distributions of sporocarps that occurred successively in 2-year periods overlapped, especially when analyzed in 9-m² unit size using the m ^* –m method. Mycorrhizas of S. pictus were distributed in more subplots than its sporocarps. Distribution of mycorrhizas and sporocarps of S. pictus generally overlapped well. The biomass of mycorrhizas and mycelia in the mycorrhizas of S. pictus was estimated at 15.5 g DW m⁻² and 6.2 g DW m⁻² (surface area) in this plot, respectively. The biomass of mycorrhizas and mycelia in the mycorrhizas supporting the production of one sporocarp (average dry weight was 0.86 g) of S. pictus was evaluated as about 16.4 and 7.3 g DW, respectively, in this plot. Received: December 20, 2001 / Accepted: August 12, 2002 Acknowledgments We thank Dr. T. Furuno, Mr. N. Kato, and Dr. I. Nakai for their help in preparing the study plot and collecting sporocarps, and Prof. K. Yokoyama for the identification of sporocarps. Thanks are also due to Dr. E. Kuno for his suggestion about analysis. Correspondence to:J. Kikuchi     

Studies on hypersaline-tolerant white-rot fungi III: biobleaching of unbleached kraft pulp by hypersaline-tolerant manganese peroxidase from a marine white rot isolate, <Emphasis Type="Italic">Phlebia </Emphasis>sp. MG-60

 A marine white rot isolate, Phlebia sp. MG-60, secreted lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase under different sea salt incubation conditions. Its MnP production was strongly enhanced by adding 3% sea salts, and the MnP showed high tolerance to sea salts and NaCl. The crude enzyme secreted at 3% sea salt concentration by Phlebia sp. MG-60, in which the main component was MnP (cMnP), was then used to bleach unbleached hardwood kraft pulp (UKP) in vitro. The pulp was brightened 11 points by 4 U of cMnP, and the kappa number was decreased 6 points when only 0.5 mM H₂O₂ was added continuously. When 0.5 mM H₂O₂ (1.22 mg H₂O₂ /g pulp) was added at the initial bleaching, the pulp brightness increased 6 points with a dosage of 4 U of cMnP. When crude MnPs were employed to bleach UKP with organic-free model white-water instead of the Milli Q water usually used, the pulp was brightened 10 and 13 points by 4 and 20 U of cMnP, respectively, and 5 and 6 points by 4 and 20 U of MnP, respectively, of Phanerochaete chrysosporium. Received: September 28, 2001 / Accepted: March 15, 2002 Correspondence to:R. Kondo     

Reaction behavior of lignin in supercritical methanol as studied with lignin model compounds

 The reaction behavior and kinetics of lignin model compounds were studied in supercritical methanol with a batch-type supercritical biomass conversion system. Guaiacol, veratrole, 2,6-dimethoxyphenol, and 1,2,3-trimethoxybenzene were used as model compounds for aromatic rings in lignin. In addition, 5-5, β-1, β-O-4, and α-O-4 types of dimeric lignin model compounds were used as representatives of linkages in lignin. As a result, aromatic rings and 5-5 (biphenyl)-type structures were stable in supercritical methanol, and the β-1 linkage was not cleaved in the β-1-type structure but converted rapidly to stilbene. On the other hand, β-ether and α-ether linkages of β-O-4 and α-O-4 lignin model compounds were cleaved rapidly, and these compounds decomposed to some monomeric compounds. Phenolic compounds were found to be more reactive than nonphenolic compounds. These results indicate that cleavages of ether linkages mainly contribute to the depolymerization of lignin, whereas condensed linkages such as the 5-5 and β-1 types are not cleaved in supercritical methanol. Therefore, it is suggested that the supercritical methanol treatment effectively depolymerizes lignin into the lower-molecular-weight products as a methanol-soluble portion mainly by cleavage of the β-ether structure, which is the dominant linkage in lignin. Received: December 19, 2001 / Accepted: April 30, 2002 Acknowledgments This research has been done under the research program for the development of technologies for establishing an ecosystem based on recycling in rural villages for the twenty-first century from the Ministry of Agriculture, Forestry and Fisheries, Japan; by a Grant-in-Aid for Scientific Research (B)(2) (no.12460144, 2001.4–2003.3) from the Ministry of Education, Culture, Sports, Science and Technology, Japan; and under the research program from Kansai Research Foundation for Technology Promotion, Japan. The authors thank them for their financial support. This study was presented in part at the 45th Lignin Symposium, Ehime, Japan, October 2000 and the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, Japan, April 2002 Correspondence to:S. Saka     

Somatic embryo culture for propagation,artificial seed production,and conservation of sawara cypress (<Emphasis Type="Italic">Chamaecyparis pisifera</Emphasis> Sieb. et Zucc.)

 Somatic embryogenesis in Chamaecyparis pisifera Sieb. et Zucc. was initiated from immature seeds collected from the end of June to early July. Mass propagation through adventitious shoot bud production from somatic embryo culture on Woody Plant (WP) medium and artificial seed production using sodium alginate was achieved. A high bud forming index value (25.8) was obtained on medium supplemented with 1 μM 6-benzylaminopurine. The conversion rates from artificial seeds under aseptic and nonaseptic conditions were 60%–100% and 10%–12%, respectively. For germplasm conservation, somatic embryos and embryogenic cells were successfully stored at 4°C (medium-term storage) and in liquid nitrogen for long-term storage. Received: December 21, 2001 / Accepted: August 1, 2002 Acknowledgments This work was supported in part by the Japan Science and Technology Corporation and in part by a Grant for Research for the Future Program from the Japan Society for the Promotion of Science. Correspondence to:E. Maruyama     

Feasibility of supercritical carbon dioxide as a carrier solvent for preservative treatment of wood-based composites

 Supercritical carbon dioxide (SC-CO₂) was tested for its potential as a carrier solvent for preservative treatment of solid wood and wood-based composites. A preliminary trial showed that the treatability of solid wood varied with its original permeability and that the SC-CO₂ treatment was not promising for refractory timber species such a Larix leptolepis Gordon. In contrast, 3-iodo-2-propynyl butylcarbamate (IPBC)/SC-CO₂ treatment resulted in enhanced decay resistance without any detrimental physical or cosmetic damage in all structural-use wood-based composites tested: medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board (OSB). Further trials under various treatment conditions [25°C/7.85 MPa (80 kgf/cm²), 35°C/7.85 MPa, 45°C/7.85 MPa, 35°C/11.77 MPa (120 kgf/cm²), and 45°C/11.77 MPa] indicated that although small changes in the weight and thickness of the treated materials were noted the strength properties were not adversely affected, except for a few cases of softwood plywood and oriented strand board. The results of this study clearly indicated that the treatment condition allowed SC-CO₂ to transport IPBC into wood-based composites, and the optimum treatment condition seemed to vary with the type of wood-based composite. Received: October 24, 2001 / Accepted: February 15, 2002 Part of this work was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001; and the 32nd Annual Meeting of the International Research Group on Wood Preservation, Nara, May 2001 Correspondence to:M. Muin     

Effects of resource plant size on rooting of <Emphasis Type="Italic">Dryobalanops lanceolata</Emphasis> cuttings

 Cuttings from older trees of the Dipterocarpaceae generally lose their ability to root. However, branches in a canopy of adult dipterocarps are a possible source of cuttings because they show juvenile characteristics in architecture due to “adaptive reiteration”, suggesting physiological rejuvenation. Effects of resource plant size on the rooting of cuttings and the possibility of using cuttings from reiterated branches of adult trees were studied for Dryobalanops lanceolata, an emergent dipterocarp species. A cutting experiment with non-mist propagators was conducted for cuttings collected from resource plants of four different size classes: <2 m, 2–5 m, 8–15 m, and 70 m in height. The smallest size class included two different age classes: <2 and >2 years old. Cuttings from the tallest resource plant were collected from reiterated branches. Rooting percentage was negatively correlated with resource plant size: 77–78% for resource plants <2 m, 63% for 2–5 m, 36% for 8–15 m, and 0% for 70 m. Rooting percentages of cuttings collected from different individuals were not different for the 2–5 m tall class, while they were significantly different for the 8–15 m tall class. Resource plant size was negatively correlated with the number of roots for rooted cuttings. No significant relationship was observed between resource plant size and mean length of each root, total root length or total root dry weight for rooted cuttings. The results suggest the possibility of collecting cuttings from relatively large resource plants up to 15 m tall and >20 years old if we chose good individuals for resource plants. The results, however, show the difficulty in using reiterated branches of adult trees as a source of cuttings for D. lanceolata. Received: October 15, 2001 / Accepted: November 11, 2002 Acknowledgments We express our sincere thanks to Dr. S. Tamura, Dr. K. Ogino, and Mr. A.A. Hamid for their kind support. The tree tower was constructed in a cooperative project between Japan and Sarawak supported by the Ministry of Education, Culture, Sports, Science and Technology, Japan (Grant NP0201). The cutting experiment was partly funded by the Nippon Life Insurance Foundation and the Japan Society for the Promotion of Science (JSPS-RFTF96R16001). Correspondence to:A. Itoh     

Differences in chemical constituents between vascular bundles and nonvascular bundles of cacao (<Emphasis Type="Italic">Theobroma cacao</Emphasis> L.) hull

 Cacao (Theobroma cacao L.) hulls were physically separated into vascular bundles (VBs) and nonvascular bundles (NVBs) to investigate their chemical compositions and the structural features of abundant polyphenolic compounds. Glucose content was determined to be 21.4% for VBs and 17.5% for NVBs, together with xylose content as 13.1% for VBs and 2.8% for NVBs. In addition, uronic acid in NVBs (12.9%) was much higher than that in VBs (5.2%). The content of total (poly)phenolic compounds (35.9%–39.1%) quantified as Klason residues (KRs) and acid-soluble phenolic compounds (ASPs) were similar in both cell types, although there were great differences in the structural characteris-tics of polyphenolic compounds. The pyrogram of VBs clearly showed high intensities of guaiacol and 4-vinylguaiacol together with low intensities of catechol and 4-methylcatechol. On the other hand, that of the NVBs showed opposite trends. These results were confirmed by alkaline nitrobenzene oxidation based on total yields of vanillin and syringaldehyde. Therefore, the accumulation of various polyphenolic compounds in cacao hulls relies strongly on the cell type and is correlated with the development of a secondary wall. Received: October 9, 2001 / Accepted: April 15, 2002 Present address: Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA Acknowledgments This project was partially supported financially by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology (no. 13375007). We thank Dr. Hadi S. Arifin, Faculty of Agriculture, Bogor Agricultural University, Indonesia, for collecting cacao fruits at the Rajamandala Cacao Plantation at Rajamandala in West Java. Correspondence to:K. Iiyama     

In-plane shear properties of the wood-based sandwich panel as a small shear wall evaluated by the shear test method using tie-rods

 The fundamental in-plane shear properties were investigated for the wood-based sandwich panel of plywood-overlaid low-density fiberboard (SW) manufactured at a pilot scale to develop it as a shear wall. The shear test method using tie-rods standardized for shear walls was applied to SW with dimensions of 260 mm square and 96 mm thick as a small shear wall and to plywood (PW) and thick low-density fiberboard (FB). The shear modulus and shear strength of PW, FB, and SW were determined. To measure the shear deformation angle, a displacement meter and strain-gauge were used. The shear moduli of PW (0.68 g/cm³) and FB (0.25–0.35 g/cm³) were 460 and 21–58 MPa/rad, respectively. The shear modulus of SW as a composite was analyzed. Some experimental models of SW were proposed (i.e., rigid-α, rigid-β, flexible, and semirigid models). The shear modulus of SW (0.35–0.40 g/cm³) evaluated based on the rigid-α and semirigid models were 73–89 and 109–125 MPa/rad, respectively. The theoretical shear modulus of SW was calculated to be 110–129 MPa/rad. Received: May 9, 2001 / Accepted: June 26, 2002 RID="*" ID="*" Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, Japan, April 2000; and the 5th Pacific Rim Bio-Based Composite Symposium, Canberra, Australia, December 2000 Acknowledgments The authors express our deep gratitude to Mr. Noritoshi Sawada (Hokushin Co.), Dr. Wong Cheng, and their cooperative members for their expert technical support for the preparation of manufacturing the thick fiberboard and sandwich panel. We are grateful also to Drs. Min Zhang, Kenji Umemura, Wong Ee Ding, and Guangping Han for their great help and advice in manufacturing the thick panels. The authors are grateful to Hokushin Co. for the fiber and resin and to Ishinomaki Gouhan Co. for the plywood. We thank Mr. Makoto Nakatani for his expert assistance when preparing the specimens for the shear test. Funding provided by the Research Fellowship of the Japan Society for the Promotion of Science for Young Scientists as a JSPS Research Fellow is also gratefully acknowledged.     

Antioxidative and antiradical activities of <Emphasis Type="Italic">Eucalyptus camaldulensis</Emphasis> leaf oils from Thailand

The leaf essential oils (six samples) from three clones of Eucalyptus camaldulensis Dehnh. were characterized by gas chromatography-mass spectrometry. Radical scavenging and antioxidant properties were investigated by the 1,1-diphenyl-2-picylhydrazyl (DPPH) assay and the β-carotene bleaching test. It was found that the whole essential oil and its fractions had significant antioxidant effects when they were tested by each method. In the DPPH assay, the E. camaldulensis leaf oils showed IC₅₀ inhibitory concentrations in the range of 1.75–12.62 mg/ml. In the β-carotene bleaching test, the IC₅₀ valued were in the range of 14.30–118.55 μg/ml. Part of this report was presented at the 18th meeting of the Chugoku-Shikoku Branch of the Japan Wood Research Society, November 2006     

Allomorphs of native crystalline cellulose I evaluated by two equatoriald-spacings

The aim of this study was to develop a facile method for categorizing native celluloses as the algal-bacterial type or the cotton-ramie type and for estimating the I_α/I_β (triclinic/monoclinic) ratio of the cellulose samples. We investigated various native celluloses by X-ray diffractometry; and discriminant analysis was carried out using two equatoriald-spacings: 0.59–0.62 nm (d ₁) and 0.52–0.55 nm (d ₂). All of the samples were classified into the two groups without error. The function used to discriminate between the two groups is represented as:Z=1693d₁ — 902d ₂ — 549, whereZ>0 indicates the algal-bacterial (I_α-rich) type andZ<0 indicates the cotton-ramie (I_β-dominant) type. Another X-ray diffraction study of hydrothermally treatedCladophora cellulose revealed the relation between thed-spacings (d ₁,d ₂) and the I_α/I_β ratio. A calibrating equation by which the I_α/I_β ratio was estimated from the two parameters,d ₁ andd ₂, was then prepared. In the case of relatively highly crystalline native celluloses, it was found that the I_α/I_β ratio is easily determined by applying the two parameters in the equation.     

Positioning precision and sampling number of DGPS under forest canopies

 Experimental results were studied to determine the relationships between positioning precision of a differential global positioning system (DGPS) and forest type, antenna height, and season, and to clarify the relationship between sampling number and the convergence of positioning precision. Observation was carried out for 24 h. Mean circular area probability (CEP₉₅) was 2.80 m for deciduous broadleaved trees, and 4.99 m for conifers. The mean CEP₉₅ taken at 7 m height (3.14 m) was higher than that at 1 m height (3.92 m) at all sites. The mean CEP₉₅ taken during the defoliation season (2.65 m) was slightly better than during the foliation season (2.96 m). There were significant differences between forest types (P < 0.001) and antenna heights (P < 0.05). Positioning precision was not noticeably improved if the sampling number was around ten or less. A sampling number of 100–1000 or more is required before substantial improvements can be expected. As long as high positioning precision is not required, it is acceptable to use 2D & 3D modes and relatively few samples to take measurements. Received: April 24, 2002 / Accepted: October 10, 2002 Correspondence to:I. Sawaguchi     

Morphological features and dietary functional components in fruit bodies of two strains of <Emphasis Type="Italic">Pholiota adiposa</Emphasis> grown on artificial beds

 The morphological features and dietary functional components of two strains (FPF-13 and Oninome-B) of Pholiota adiposa (numerisugitake mushroom) grown on artificial bed blocks were examined. The components examined were chitin, mannitol, trehalose, guanosine 5′-monophosphate, ergosterol, and β-glucan. There was a significant difference in the external shape of the two strains. However, the differences in the contents of functional components between the two strains, as well as between the pilei and stipes of the strains, were small. In both strains the trehalose content was much higher than the mannitol content, in contrast to those of Lentinula edodes. From a commercial point of view, Oninome-B has a clear advantage over other strains of P. adiposa owing to its less removable scale. Received: May 15, 2002 / Accepted: June 10, 2002 Acknowledgment The authors thank Dr. F. Eguchi (Takasaki University of Health and Welfare) for his technical advice on the β-glucan analysis. Part of this report was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001 Correspondence to:K. Shimizu     

Extraction and decomposition of hiba wood into valuable chemicals using stepwise temperature supercritical carbon dioxide treatment

Hiba (Thujopsis dolabrata) wood was treated with supercritical carbon dioxide (scCO₂) at stepwise temperature increments from 50° to 400°C continuously so that extractives (dichloromethane-soluble and -insoluble phases) and solid residues were obtained. The yield of extractives from hiba wood increased with increasing extraction temperature. The volatile compounds in the dichloromethane-soluble phase from scCO₂ extraction at 50°C contained only terpenoids. However, the volatile compounds in the dichloromethane-soluble phase from scCO₂ extraction at 300°C not only contained terpenoids but also phenols, furans, hydrocarbons, and organic acids. The yield of β-thujaplicin, which is a useful compound in hiba wood, increased with increasing extraction temperature from 50°C to 300°C; the optimal conditions for extracting β-thujaplicin were 300°C and 19.61 MPa. Further study of degradated compounds from the cellulosic and lignic materials of hiba wood after stepwise high-temperature scCO₂ treatment above 300°C may provide clues to its efficient use.     

Sampling procedure for density estimation of bamboo galls induced by <Emphasis Type="Italic">Aiolomorphus rhopaloides</Emphasis> (Hymenoptera: Eurytomidae) in a bamboo stand

 To establish a sampling procedure for estimating the density of bamboo galls induced by Aiolomorphus rhopaloides Walker (Hymenoptera: Eurytomidae) in a stand of bamboo Phyllostachys heterocycla (Carr. Mitf.) (Monocotyledoneae: Gramineae), 5–12 bamboo culms were cut at random in late March of each year during 1998–2001 just before gall-maker emergence. The number of galls on the branches of each bamboo culm was counted. The spatial patterns of the galls on the culms in the stand and on the branches within each culm were measured by Iwao's patchiness regression. Galls were distributed contagiously both on culms and on branches. Current bamboo culms that emerged the previous summer did not require sampling because no galls were observed on them. Except for this, there was no difference in gall density on young and old culms, suggesting that it is not necessary to distinguish them. There were few (<4%) galls above 6 m height during the 4 years. There was no significant difference in gall density up to 4 m and above 4 m, suggesting that branches up to 4 m can be sampled with confidence. Kuno's two-stage sampling method at different precision levels showed that the number of culms to be sampled varied with gall density. For example, at mean density m = 1.0 per branch when the number of sampled branches per culm is 10, a total of 24 culms is required to estimate gall number at a precision level of D = 0.2, where D is the ratio of standard error to mean. Received: July 10, 2002 / Accepted: November 25, 2002 Acknowledgments I thank Dr. K. Kamijo for insect identification. Thanks are also due to the members of the Laboratory of Forest Protection for their kind help with the fieldwork. This study was supported in part by a Grant-in-Aid for Scientific Research (No. 11460068) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.     

Root biomass and distribution of a <Emphasis Type="Italic">Picea–Abies</Emphasis> stand and a <Emphasis Type="Italic">Larix–Betula</Emphasis> stand in pumiceous Entisols in Japan

Root biomass and root distribution were studied in Entisols derived from the thick deposition of volcanic pumice on Hokkaido Island, Japan, to examine the effect of soil conditions on tree root development. The soil had a thin (<10 cm) A horizon and thick coarse pumiceous gravel layers with low levels of available nutrients and water. Two stands were studied: a Picea glehnii–Abies sachalinensis stand (PA stand) and a Larix kaempferi–Betula platyphylla var. japonica stand (LB stand). The allometric relationships between diameter at breast height (DBH) and aboveground and belowground biomass of these species were obtained to estimate stand biomass. The belowground biomass was small: 30.6 Mg ha₋₁ for the PA stand and 24.3 Mg ha₋₁ for the LB stand. The trunk/root ratios of study stands were 4.8 for the PA stand and 4.3 for the LB stand, which were higher than those from previous studies in boreal and temperate forests. All species developed shallow root systems, and fine roots were spread densely in the shallow A horizon, suggesting that physical obstruction by the pumiceous layers and their low levels of available water and nutrients restricted downward root elongation. The high trunk/root ratios of the trees may also have resulted from the limited available rooting space in the study sites.