Leaching characteristics of homologues of benzalkonium chloride from wood treated with ammoniacal copper quaternary wood preservative

In Japan, ammoniacal copper quaternary wood preservatives type-1 (ACQ-1), which contains copper and benzalkonium chloride as its active ingredients, is among the most widely used wood preservatives in the pressure treatment of wood. Benzalkonium chloride (BAC) in commercial ACQ-1 products mainly comprises C12 and C14 homologues. In the present study, the leaching characteristics of these BAC homologues were investigated using the heartwood and sapwood portions of Japanese cedar, Japanese larch, and Sakhalin fir treated with ACQ-1 and 1% monoethanolamine (MEA) solution containing equimolar amounts of homologues. Distilled water (DW) and artificial seawater (SW) were used as leaching media. Consequently, it was observed that the leaching rate of the C12 homologue tended to be higher than that of the C14 homologue in DW. The leaching of C12 homologues was accelerated by using SW, resulting in a significantly higher leaching rate than the C14 homologue using SW. It was thought that the difference in the hydrophobicities based on alkyl chain lengths resulted in these phenomena. However, when the heartwood portion of Japanese larch was treated with the homologues in MEA, the leaching rate of the C14 homologue was significantly higher than that of the C12 homologue.     

Effects of alkyl chain length and the mixing of homologues with different alkyl chains on the leaching characteristics of benzalkonium chloride

Benzalkonium chloride (BAC) is the active ingredient of ACQ-1, one of the most widely used wood preservatives in Japan. BAC in ACQ-1 comprises homologues with different alkyl chains: C12 comprises 74%; C14 26%; and C16 < 1%. To clarify the leaching characteristics and the factors affecting the leaching of BAC homologues, wood specimens treated individually with the C12, C14, and C16 homologues were used in a leaching experiment with distilled water (DW) and artificial sea water (SW). The leaching rates of the BAC homologues were accelerated by the SW, and the order of the leaching rate in both DW and SW was C12 > C14 > C16. When the specimens were treated with a mixture of two of the three homologues, the leaching rates of the C14 and C16 homologues from specimens treated with a solution containing C14 and C16 were lower than that from specimens treated with a solution containing the C14 or C16 homologue together with C12. From the adsorption isotherm of the homologues it is assumed that the formation of BAC aggregates on the treated wood is related to their leaching. BACs consisting of mainly C14 and C16 are thought to be suitable for reducing leaching, particularly in marine usage.     

Leaching behaviour of benzalkonium chloride homologues in soil and water solutions

Experiments were carried out to determine the leaching mechanism of benzalkonium chloride (BAC) from treated wood in soil. Wood specimens were treated with C12, C14 and C16 BAC homologues and exposed to soil or aqueous solutions containing oxalic acid, sodium oxalate, hydrochloric acid, sodium chloride or sodium humate. The leaching rates of the homologues in soil were close to each other and all higher than in distilled water. The order of the rates in soil (C12 ≈ C14 ≈ C16) was different from that in distilled water (C12 > C14 > C16). The leaching rates of the homologues in the acidic solutions and their salts solution were also higher than in distilled water, and the order of the rates was the same as in distilled water. The aqueous solution of sodium humate also accelerated homologue leaching but resulted in an order of C16 > C14 > C12. The BAC leaching acceleration mechanism by humate was thought to be different from the mechanisms of acids and their salts and plays an important role in the leaching behaviour of BAC in soil.     

Allelopathic effect of larch leaching on ash growth in mixed forest

lntroductionConcerningthemechanismoftheinteractionbe-tWeentreespeciesinthelarch(LafisgmelinI)-ash(PraxiPusmandShuFbe)mixedforest,wehavestudiedtheaIIelopathiceff6ctsoftheIarchvolatilematter,litterandrootsecretion.onthegroWthofash.TheobtainedresultsshowedclearIythatthelarchvoIatiIematt6rplayedaninhibitivepart,andboththeIarchIitt6randrootsecretionpIayedanobviousfystimuIatingpaFtontheashgroWth(Wu2oooa,2ooob,2oooc).Thispapermakesastudyofanotherallelo-pathicway(Ieaching)betWeenlarchandash.T…     

Comparison of organic matter dynamics in soil between Japanese cedar (Cryptomeria japonica) forest and adjacent Japanese red pine (Pinus densiflora) forest established on flatland

In order to clarify the effects of tree species on organic matter dynamics in soil, we investigated the amount of forest floor material, leaf litter decomposition rate, soil chemical characteristics, soil respiration rate and cellulose decomposition rate in a Japanese cedar forest (cedar plot) and an adjacent Japanese red pine forest (pine plot) established on a flatland. The amount of forest floor material in the cedar plot was 34.5 Mg ha⁻¹ which was greater than that in the pine plot. Because the leaf litter decomposition rate was higher in the pine plot than in the cedar plot, it is likely that the difference in the amount of forest floor material between the plots is caused by the difference in the leaf litter decomposition rate. The C concentrations of soil in the cedar plot were 1.2–2.1 times higher than those in the pine plot. Soil pH(H₂O)s in the cedar plot were significantly higher than those in the pine plot. The soil respiration rates and the rates of mineralized C in the cedar plot byin vitro incubation were higher than those in the pine plot. From this result, it is assumed that soil organic matter in the cedar plot was decomposed relatively faster compared with the pine plot. Furthermore, microbial activities, which were reflected as cellulose decomposition rates in the cedar plot, were higher than those in the pine plot. A part of this paper was presented at the 109th Annual Meeting of the Japanese Forestry Society (1998).     

Allocation of 14C-carbon in two species of larch seedlings infected with ectomycorrhizal fungi

The flow of labeled carbon in ectomycorrhizal and non-ectomycorrhizal seedlings of Japanese larch (Larix kaempferi Sarg.) and its F1 hybrid (Larix gmelinii Rupr. x L. kaempferi) was studied. Larch seedlings were grown in a greenhouse for 110 days with larch forest soil (FM) or Suillus grevillei (SM) inoculum, or in the absence of ectomycorrhizal fungi (NM). Shoots of colonized and NM seedlings were exposed to a pulse of 14CO2 for 1 h under natural light. Seedlings were harvested following 0, 6 and 24 h of exposure to 14CO2. At the final harvest, SM seedlings of Japanese larch and hybrid larch allocated 2.6 and 2.5% more 14C, respectively, to roots than NM seedlings. In contrast, FM seedlings of Japanese larch and hybrid larch allocated 6.5 and 18.0% more 14C, respectively, to the stem than NM seedlings. Of the total 14C detected in needle, stem and root fractions, FM and SM seedlings allocated a greater proportion than NM seedlings, perhaps because FM and SM seedlings had significantly (P < 0.05) higher photosynthetic rates than NM seedlings. As a result, FM and SM seedlings had greater dry masses than NM seedlings. Concentrations of nitrogen and phosphorus in FM and SM seedlings were significantly (P < 0.05) higher than in NM seedlings, as was stomatal conductance.     

Distribution of heartwood extractives in hybrid larches and in their related European and Japanese larch parents: relationship with wood colour parameters

Heartwood is the most valuable part of larch timber when either natural durability or aesthetic aspects of the wood are required. Both properties are directly linked to chemical extractives and particularly to phenols. Based on a broad sample of trees (583) from European and Japanese larch and their interspecific hybrid, we investigated the variability in phenolic content, and particularly of two major compounds, Taxifolin (Tax) and Dihydrokaempferol (DHK), and their link with wood colour. At the individual wood sample level, phenolic contents ranged from 6.0 to 55.9 mg eq. Tax/g DW. Taxifolin was the most abundant constituent (range: 1.3–41.7 mg/g DW) compared with DHK (0.5–13.7 mg eq. Tax/g DW). A high variability among taxa, genotypes and individual trees within taxa and within trees was observed. Japanese larch had the highest amount of total phenols and of Taxifolin and European larch the lowest. For DHK, Japanese larch was the poorest compared with European larch. Hybrid larch had both a high content of Taxifolin and of DHK. Variability for colour parameters was on average weaker than for phenolic content but still large enough to show significant differences between taxa. Correlations between colour parameters and extractives were moderate to weak. At the mean genotype level, a good link (r > 0.51, p < 0.001) was found between a* (red–green axis in CIELAB) and total phenols and Taxifolin contents and between L* (Lightness) and DHK content (r > 0.54). The broad variability observed in this study at different levels for phenolics offers opportunities for breeders to genetically improve the quality of larch heartwood, in particular in relation to decay resistance.     

In vitro screening of angiotensin I-converting enzyme inhibitors from Japanese cedar (Cryptomeria japonica)

Screening and isolation of angiotensin I-converting enzyme (ACE) inhibitors from Japanese cedar (Cryptomeria japonica) based on the in vitro ACE inhibitory assay were attempted. The ethanol extract from outer bark showed the highest inhibitory activity (IC₅₀ is 16g/ml) among 24 extracts prepared from roots, leaves, heartwood, sapwood, inner bark, and outer bark by successive extraction with four solvents. The fractionation of the outer bark ethanol extract followed by the bioassay resulted in the isolation of two strong ACE inhibitors, catechin and dimeric procyanidin B3. The bioassay of three flavan-3-ols including (+)-catechin and six flavones revealed that most of these compounds have high ACE inhibitory activity. The results suggest that the phenolic hydroxyl group at the C7 position and heterocyclic oxygen atom of these compounds are important for expressing the inhibitory activity.     

三峡地区高山乡土造林树种选择研究

自上世纪70年代以来,大老岭林场开展了北亚热带三峡地区高山造林树种生态调查[1]。依据调查结果:1981年选择玉兰、银鹊、鹅掌秋、鄂枫杨、漆树、大叶杨、山桐子、桦榛、白辛、檫木、珙桐、香椿、亮叶桦、水曲柳等阔叶乡土树种和油松、华山松、落叶松、柳杉等针叶乡土树种开展栽培试验研究。通过各树种成活率、保存率及生长量26 a(2004)调查表明:26 a(2004)生现实遗传增益银鹊比11个阔叶树种材积提高26.8%,比其它10个阔叶树种材积提高32.0%;日本柳杉比4个针叶树种材积提高36.5%,比其它3个针叶树种材积提高48.8%。银鹊,日本柳杉最适宜三峡山区生长,营造银鹊、日本柳杉工业用材林,可大力提高新造林分生产力,现实遗传增益15%以上,取得较好的经济、社会和生态效益。     

母株年龄、激素种类及其浓度对日本落叶松扦插生根的影响

系统地研究了全光雾插条件下母株年龄、激素种类及其浓度对日本落叶松半木质化插穗生根的影响,并在此基础上利用隶属函数法对各处理的生根效果进行了综合评价,分别为不同年龄阶段的落叶松扦插选配出最佳激素种类及其浓度的处理组合,12.5、8.5 a子代林插穗经最佳组合处理后生根率分别可达78.8%、92.5%,极大地提高了较高年龄日本落叶松扦插繁殖的生根能力.三因素方差分析结果表明,母株年龄(A)、激素种类(B)和激素浓度(C)对落叶松插穗生根率、生根量和偏根率等生根性状的影响达极显著或显著水平,同时三因素互作效应(A×B×C)及双因素互作效应(A×B、A×C、B×C)对绝大多数性状的影响也很显著.根据分年龄阶段进行的激素种类、浓度及其互作效应的比较结果,可以看出处理间生根性状的变化缺乏明显的规律性.     

Effects of root zone trenching on soil nitrogen dynamics in Japanese cedar and cypress plantations

The effects of root exclusion and planted tree species on soil nitrogen (N) dynamics were examined at two plantations, one planted with Japanese cedar and the other with Japanese cypress. We set up ten 1 × 1 × 0.2-m-deep trenched sites and ten untrenched control sites at each plantation. We measured the pool size and leaching of inorganic N at each site for 2 years and the net N mineralization 1 and 2 years after trenching. Despite similar soil conditions, the cedar plantation showed higher net N mineralization than the cypress plantation. Stopped tree uptake of N was expected to cause an increased pool size and leaching of inorganic N at the trenched sites. Nevertheless, we found no significant increase in those variables at both plantations. The trenched cypress sites showed no decrease in the net N mineralization during the 2 years after trenching. However, the net nitrification at the trenched cypress sites increased remarkably at the deeper horizons in comparison with that at the control sites. Enhanced nitrification might result from improved ammonium availability through root exclusion. Net N mineralization at the trenched cedar sites decreased more than 60% compared with that at the control sites 2 years after trenching. Higher nitrification potential at the cedar plantation and enhanced nitrification potential at the trenched cypress sites never resulted in increased leaching of N, due to added fine root litter which acted as an immobilization agent for excess N, thus preventing N loss.     

Soil nitrogen dynamics during stand development after clear-cutting of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>) plantations

We examined soil N dynamics, including inorganic N concentration, net N transformation rates, and estimated plant N uptake (EPNU) from soil N budgets, and litterfall inputs, in five Japanese cedar plantation stands of different ages (5, 16, 31, 42, and 89 years) in the Mt Gomadan Experimental Forest (GEF). Net soil N mineralization and nitrification rates did not differ significantly between the youngest and oldest stands; soil moisture and inorganic N concentration were higher in the youngest stand. The EPNU was highest in the 16-year-old stand and lowest in the 31-year-old stand, and had a significant negative correlation with litter C:N ratio. The oldest (89-year-old) stand had a higher soil C:N ratio, lower proportion of nitrification rate to mineralization rate (%NIT), and higher estimated plant NH₄ ⁺ uptake than did the other stands, indicating that changes of soil organic matter quality can alter soil N dynamics. These results suggest that as a Japanese cedar plantation develops, soil N dynamics can be altered by the quantity and quality of input litter and soil organic matter, and can generate the imbalance between N supply from soil and N demand by plant.     

Spectrophotometric assay of a wood preservative, didecyldimethylammonium chloride (DDAC), in aqueous solution

A spectrophotometric assay based on the color reaction between didecyldimethylammonium chloride (DDAC) and 4-[4-(dipropylamino)phenylazo]-benzenesulfonic acid (propyl orange) was used for the determination of DDAC as a wood preservative. The assay was carried out using a propyl orange solution at pH 2.9. The visible absorbance spectrum of propyl orange showed an absorbance maximum at 510 nm, which decreased continuously with increasing DDAC concentration from 0 to 20 ppm. A linear correlation was observed at a DDAC concentration lower than 8 ppm. To apply this assay method to determine DDAC retention in treated wood, the influence of wood extractives on the assay was investigated. Wood extractives from sapwood and heartwood of Japanese cedar, Hinoki cypress, Japanese larch, and Western hemlock showed no influence on DDAC determination except in the case of heartwood from Japanese cedar and Hinoki cypress, which gave apparent DDAC concentrations higher than the actual values. However, it was also found that absorbance measurement at 477 nm solved this overestimation and gave precise values. It was concluded that this assay is a viable alternative to the current methods for DDAC determination.     

Comparison of two coniferous plantations in central Japan with respect to forest productivity, growth phenology and soil nitrogen dynamics

Japanese cypress (Chamaecyparis obtusa Endl.) and Japanese cedar (Cryptomeria japonica D. Don) are common species for plantation forestry in Japan. Cypress is conventionally planted on sites of low fertility whereas for cedar high fertility sites are used. Objectives of this study were to compare the productivities of cypress and cedar plantations grown on adjacent sites where common properties of soils, such as pH values and C and N contents, were similar, and to relate the N cycling at their site with productivities. The stem diameter of trees, aboveground litter production and fine root biomass were measured as indices of forest productivity. Parameters of N cycling included pools of total N and mineral N (ammonium + nitrate), annual N leaching, and potentially mineralizable N. The radial stem increment of the two tree species was similar. However, cedar site had higher total basal area and annual basal increment than cypress site reflecting higher tree density on the cedar site. Aboveground litter, fine root biomass, soil organic matter, and N turnover were higher on the cedar site than on the cypress site. However, litter production and fine root biomass per unit basal area was greater at the cypress site. Phenological pattern of stem growth and periodical litter production were similar for both species during the study period (1992–2000), but showed distinct annual variations caused by the fluctuation in the ambient temperature and precipitation. Mineral N content and the N mineralization potential were greater on the cedar site, indicating greater N availability and higher total tree productivity at the cedar site than those at the cypress site. When provided with more space in the canopy to expand more needles and in the soil to develop more fine roots to exploit sufficient resources, the individual cypress trees have the potential to grow faster. On fertile site and at lower tree density, thicker logs of cypress might be yielded.     

Induced resistance of Norway spruce,variation of phenolic compounds and their effects on fungal pathogens

Three clones of Norway spruce (Picea abies) were studied for their response to mass‐inoculation with the blue‐stain fungus Ceratocystis polonica. The effect of different pretreatments (fungal inoculation and wounding) before mass‐inoculation was investigated for their possible role in an acquired resistance reaction. Pretreated trees showed enhanced resistance to the subsequent mass‐inoculation relative to control trees that received no pretreatment. Furthermore, the fungal colonization of inoculated trees was less than that of wounded trees. The phenolic content of the bark, analysed by RP‐HPLC, was compared in trees receiving different treatments. Trees inoculated with C. polonica had higher average concentration of (+)‐catechin, taxifolin and trans‐resveratrol than wounded trees. Both inoculated and wounded trees had higher average concentrations of these compounds than control trees. The effect of the phenolic extract of Norway spruce bark on the growth of the root rot fungus Heterobasidion annosum and the blue‐stain fungi C. polonica and Ophiostoma penicillatum were investigated in vitro. Heterobasidion annosum was not negatively affected, and the extracts had fungistatic effects on the blue‐stain fungi. The growth of O. penicillatum was more inhibited than the growth of the more aggressive C. polonica.     

Screening for condensed tannin-degrading fungi with a synthetic <Superscript>14</Superscript>C-labeled compound

To find fungi that are potent for degradation of condensed tannin, a two-step screening was used. This involved measurement of fungal growth rate on Japanese cedar (Cryptomeria japonica) bark, followed by determination of [¹⁴C]-labeled CO₂ generated from fungal degradation of synthetic [¹⁴C]-labeled condensed tannin model. In the first screening, 75 strains of wood rot fungi were tested, and 19 strains effectively decreased bark weight and/or the weight of the methanol-soluble fraction. For the second screening, [¹⁴C]-labeled condensed tannin model compound was synthesized in 11.8% yield based on radioactivity measurements. Over the incubation period, Coriolus hirsutus K-2671, Lentinus edodes Is, and Lampteromyces japonicus Nn showed higher cumulative [¹⁴C]-labeled CO₂ emissions than the other strains and mineralized the [¹⁴C]-labeled condensed tannin model compound by 3.7%, 3.0%, and 3.0%, respectively. Fractionation of the methanol extracts from the medium by gel permeation chromatography after fungal treatment suggested that fungi that can induce the emission of significant levels of [¹⁴C]-labeled CO₂ can extensively depolymerize condensed tannins.     

单宁用于带锈钢铁防蚀处理的研究

用栲胶及其增纯产物和相应的单宁－铁螯合物代替工业单宁酸成功地用于带锈钢铁的抗蚀处理，研究了处理剂的配方、配制方法，并对其性能进行了测试，指标均达到或超过了工业单宁酸。     

Dimensional stabilization of wood treated with furfuryl alcohol catalysed by borates

Furfuryl alcohol has a sufficiently small molecular size, which allows impregnation into wood and can be polymerized in the cell walls. Polymerization can be accomplished using a catalyst, heat or penetrating radiation. This research illustrates a natural wood polymer composite (NWPC) that was obtained under the catalytic effect of borates. Furfuryl alcohol (FA) and borates were mixed at different ratios before treatment. When borates alone are used, they were totally leached from wood after cyclic leaching periods. However, this was not encountered with the mixture of furfuryl alcohol and borates. Furfuryl alcohol considerably improved antiswelling efficiency by about 85% for both Japanese cedar ( Cryptomeria japonica) and Scots pine ( Pinus sylvestris L.) wood specimens. Results of the leaching tests of borate indicated that boric acid readily lost its boron content in the early cycles of the leaching periods and the highest leaching rate of boron was observed at the first leaching cycle (512 ppm). When furfuryl alcohol mixed with borates, boron was released to the leaching water at slower amounts, suggesting the possibility of longer protection of treated wood in service.     

Feeding responses of the western dry-wood termite <Emphasis Type="Italic">Incisitermes minor</Emphasis> (Hagen) (Isoptera: Kalotermitidae) against ten commercial timbers

Five Japanese timbers, four timbers from the USA, and one Malaysian timber were evaluated for their resistance to the invasive dry-wood termite Incisitermes minor (Hagen) using laboratory choice and no-choice feeding tests with holed specimens. The highest survival rates of I. minor in both the heartwood and sapwood no-choice feeding tests were more than 70% after 3 months. When offered sapwood and heartwood choice feeding tests and the combined choice feeding tests, the highest survival rates of I. minor were more than 75% after 3 months. With regards to the percentage of wood mass losses in the no-choice and choice feeding tests, karamatsu (Larix leptolepsis), buna (Fagus crenata), and Douglas fir (Pseudotsuga menziesii) were classified as “resistant” species among the ten sapwood specimens. In the heartwood no-choice and choice feeding tests, the resistant species were buna, karamatsu, Douglas fir, sugi (Cryptomeria japonica), akamatsu (Pinus densiflora), and western red cedar (Thuja plicata). The ranking of the resistance of the ten commercial timbers against I. minor was buna > karamatsu > sugi > western red cedar > Douglas fir > rubber > western hemlock > hinoki > spruce.