Dynamics of 15N natural abundance in wood-decomposing fungi and their ecophysiological implications

Nine species of basidiomycota and one species of ascomycota were grown in an ammonium sulphate media and on beech wood; and the general ¹⁵N dynamic patterns of the hyphae were examined. The fungal body initially became depleted in ¹⁵N in both the types of incubation. However, the underlying mechanisms were quite different, that is, significant fungal ¹⁵N drop on the beech wood is associated with the fungal N reallocation and the uptake of atmospheric ammonia and/or NO_x, in addition to isotope fractionation during assimilation. Although the ¹⁵N values of the wood-decomposing basidiocarps were generally close to the ¹⁵N values of the wood, it does not always indicate that the wood derived N was the sole N source for the fungi throughout the growth periods as shown in our wood-decomposing experiment.     

Investigation of growth responses in saprophytic fungi to charred biomass

We present the results of a study testing the response of two saprophytic white-rot fungi species, Pleurotus pulmonarius and Coriolus versicolor, to charred biomass (charcoal) as a growth substrate. We used a combination of optical microscopy, scanning electron microscopy, elemental abundance measurements, and isotope ratio mass spectrometry (¹³C and ¹⁵N) to investigate fungal colonisation of control and incubated samples of Scots Pine (Pinus sylvestris) wood, and charcoal from the same species produced at 300 °C and 400 °C. Both species of fungi colonise the surface and interior of wood and charcoals over time periods of less than 70 days; however, distinctly different growth forms are evident between the exterior and interior of the charcoal substrate, with hyphal penetration concentrated along lines of structural weakness. Although the fungi were able to degrade and metabolise the pine wood, charcoal does not form a readily available source of fungal nutrients at least for these species under the conditions used in this study.     

Nitrogen Isotope Ratios in Different Compartments of a Mixed Stand of Spruce,Larch and Beech Trees and of Understorey Vegetation Including Fungi

Abstract

Natural nitrogen isotope ratios were measured in different compartments (needles or leaves and twigs of different age classes and crown positions, roots and soil of different horizons) of spruce (Picea abies), larch (Larix decidua) and beech (Fagus sylvatica) trees in an 11-year-old mixed stand in the Fichtelgebirge, NE Bavaria, Germany. In addition, samples of understorey vegetation (mainly ericaceous shrubs and grass) and of ectomycorrhizal and saprophytic fungi were analyzed. The δ¹⁵N values found for all samples ranged between ?7.5 and + 4.5‰. No significant differences were found for the nitrogen isotope ratios of the three tree species despite of their evergreen versus deciduous foliage and despite of their different rooting depth. Ericaceous shrubs had the most negative and fungi and soil from the mineral horizon the most positive δ¹⁵N values. Positive δ¹⁵N values of the fungi indicate their ability to utilize organic soil nitrogen, but the data do not unequivocally show that plants forming mycorrhizas profit from this organic nitrogen source.     

Potential for assessing long-term dynamics in soil nitrogen availability from variations in delta15N of tree rings

Numerous researchers have used the isotopic signatures of C, H, and O in tree rings to provide a long-term record of changes in the physiological status, climate, or water-source use of trees. The frequently limiting element N is also found in tree rings, and variation in its isotopic signature may provide insight into long-term changes in soil N availability of a site. However, research has suggested that N is readily translocated among tree ring of different years; such infidelity between the isotopic compositions of the N taken up from the soil and the N contained in the ring of that growth year would obscure the long-term N isotopic record. We used a 15-year 15N-tracer study to assess the degree of N translocation among tree rings in ponderosa pine (Pinus ponderosa) trees growing in a young, mixed-conifer plantation. We also measured delta13C and delta15N values in unlabeled trees to assess the degree of their covariance in wood tissue, and to explore the potential for a biological linkage between them. We found that the maximum delta15N values in rings from the labeled trees occurred in the ring formed one-year after the 15N was applied to the roots. The delta15N value of rings from labeled trees declined exponentially and bidirectionally from this maximum peak, toward younger and older rings. The unlabeled trees showed considerable interannual variation in the delta15N values of their rings (up to 3 and 5 per thousand), but these values correlated poorly between trees over time and differed by as much as 6 per thousand. Removal of extractives from the wood reduced their delta15N value, but the change was fairly small and consistent among unlabeled trees. The delta13C and delta15N values of tree rings were correlated over time in only one of the unlabeled trees. Across all trees, both delta13C values of tree rings and annual stem wood production were well correlated with annual precipitation, suggesting that soil water balance is an important environmental factor controlling both net C gain and transpirational water loss at this site. Our results suggest that interannual translocation of N among tree rings is substantial, but may be predictable enough to remove this source of variation from the tree-ring record, potentially allowing the assessment of long-term changes in soil N availability of a site.     

Plant delta(15)N associated with arbuscular mycorrhization, drought and nitrogen deficiency

It has long been evident that plant (15)N chiefly reflects the processes which fractionate (15)N/(14)N rather than the (15)N of plant N source(s). It has emerged recently that one of the most important fractionating processes contributing to the whole plant (15)N is the presence/absence, type or species of mycorrhiza, especially when interacting with nutrient deficiency. Ecto- and ericoid mycorrhizas are frequently associated with (15)N-depleted foliar (15)N, commonly as low as -12 per thousand. As shown by the present study, plants having no mycorrhiza, or those infected with various species of arbuscular mycorrhiza (AM)-forming fungi, interact with varying concentrations of soil nitrogen [N] and moisture to enrich plant (15)N by as much as 3.5 per thousand. Hence the lack of a mycorrhiza, or variation in the species of AM-forming fungal associations, can account for about 25% of the usually reported variations of foliar (15)N found in field situations and do so by (15)N enrichment rather than depletion. Copyright 1999 John Wiley & Sons, Ltd.     

Moisture Migration in Wood Under Heating Measured by Thermal Neutron Radiography

The article addresses the transport of moisture due to high-temperature gradients resulting from heating by means of thermal neutron radiography. Moisture migration due to heating is quantified along the orthotropic directions of two wood species, spruce and beech, with high spatial and moisture content resolution. As the heat wave is propagating into the wood, the moisture content in the heated zone rapidly decreases, and moisture is transported due to the high-temperature gradient ahead of the heated zone, resulting in a zone with higher moisture content. Both the drying and the moisture accumulation areas evolve non-uniformly, depending on wood microstructure and orientation.     

Effects of surface inactivation, high temperature drying and preservative treatment on surface roughness and colour of alder and beech wood

Although extensive research has been conducted in wood surface quality analysis, a unified approach to surface quality characterisation does not exist. Measurements of the variation in surface roughness and surface colour are used widely for the evaluation of wood surface quality. Colour is a basic visual feature for wood and wood-based products. Colour measurement is one of the quality control tests that should be carried out because the colour deviations are spotted easily by the consumers. On the other hand, a common problem faced by plywood manufacturers is panel delamination, for which a major cause is poor quality glue-bonds resulting from rough veneer. Rotary cut veneers with dimensions of 500 mm × 500 mm × 2 mm manufactured from alder (Alnus glutinosa subsp. barbata) and beech (Fagus orientalis Lipsky) logs were used as materials in this study. Veneer sheets were oven-dried in a veneer dryer at 110 °C (normal drying temperature) and 180 °C (high drying temperature) after peeling process. The surfaces of some veneers were then exposed at indoor laboratory conditions to obtain inactive wood surfaces for glue bonds, and some veneers were treated with borax, boric acid and ammonium acetate solutions. After these treatments, surface roughness and colour measurements were made on veneer surfaces. High temperature drying process caused a darkening on the surfaces of alder and beech veneers. Total colour change value (ΔE^*) increased linear with increasing exposure time. Among the treatment solutions, ammonium acetate caused the biggest colour change while treatment with borax caused the lowest changes in ΔE^* values. Considerable changes in surface roughness after preservative treatment did not occur on veneer surfaces. Generally, no clear changes were obtained or the values mean roughness profile (R_a) decreased slightly in R_a values after the natural inactivation process.     

Heat capacity of Bio-SiC and SiC/Si ecoceramics prepared from white eucalyptus, beech, and sapele tree wood

This paper reports on measurement of the heat capacity at constant pressure C _p of silicon bio-carbide prepared within the 5–300 K temperature interval from beech tree wood (bio-SiC(BE)), and within 80–300 K, from tree wood of sapele (bio-SiC(SA)), as well as SiC/Si ecoceramics of beech, sapele, and white eucalyptus wood. It has been shown that in bio-SiC(BE) the measured heat capacity contains a significant contribution of surface heat capacity, whose magnitude decreases with increasing temperature. Of the ecoceramics, only SiC/Si(SA) characterized by a high enough porosity has revealed a small contribution to the heat capacity coming from its surface component. The experimental results obtained are discussed.     

木材种类的近红外光谱和模式识别

木材的种类识别是木材加工和贸易的一个重要环节,传统的木材种类识别方法主要有显微检测法和木材纹理识别法,其操作繁琐,耗时长,成本高,不能满足当前需求。本研究利用木材的近红外光谱(NIRS)结合模式识别方法,以期实现木材种类的快速准确识别。采用近红外光谱结合主成分分析法(PCA)、偏最小二乘判别分析法(PLSDA)和簇类独立软模式法(SIMCA)三种模式识别对58种木材进行种类鉴别研究;5点平滑、标准正态变量变换(SNV)、多元散射校正(MSC)、Savitzky-Golay一阶导数(SG 1st-Der)和小波导数(WD)五种光谱预处理方法用于木材光谱的预处理;校正集和测试集样品的正确识别率(CRR)用于模型的评价。采用PCA方法,通过样品的前三个主成分空间分布图分辨木材种类的聚类情况。在建立PLSDA模型,原始光谱的正确识别率最高,分别为88.2%和88.2%;5点平滑处理的光谱校正集和测试集的CRR分别为88.1%和88.2%;SNV处理的光谱校正集和测试集的CRR分别为84.4%和84.5%;MSC处理的光谱校正集和测试集的CRR分别为83.1%和84.2%;SG 1st-Der处理的光谱校正集和测试集的CRR分别为81.8%和82.7%;WD(小波基为“Haar”,分解尺度为80)处理的光谱校正集和测试集的CRR分别为87.3%和87.2%。可知,在PLSDA模型中,木材光谱未经预处理种类识别效果最后好。在建立SIMCA模型过程中,原始光谱的校正集和测试集的CRR分别为99.7%和99.4%;5点平滑处理的光谱校正集和测试集的CRR分别为100%和100%;SNV处理的光谱校正集和测试集的CRR分别为99.5%和99.1%;MSC处理的光谱校正集和测试集的CRR分别为99.0%和98.4%;SG 1st-Der的光谱校正集和测试集的CRR分别为81.8%和82.7%;WD处理的光谱校正集和测试集的CRR分别为100%和100%。可知,在SIMCA模型中,木材光谱经平滑和小波导数处理后的识别效果最好,且光谱的校正集和测试集CRR都为100%。采用三种模式结合五种不同的预处理方法对木材近红外光谱进行定性建模识别时,由于木材样本属性复杂,主成分分布图相互交织,PCA无法识别出58种木材;原始光谱的PLSDA模型可以得到较好的判别模型,但校正集和测试集的CRR只有88.2%和88.2%;木材光谱经过5点平滑或WD预处理后的SIMCA模型可达到最好的识别效果,校正集和测试集的CRR均为100%,且WD-SIMCA模型因子数比5点平滑SIMCA模型小,模型更为简化,故WD-SIMCA为58种木材种类识别的最优模型。研究表明光谱预处理方法可以有效的提高木材种类识别精度,有监督模式识别方法SIMCA可以用来建立有效的木材识别模型,近红外光谱结合模式识别可以为木材种类的识别提供一种快速简便的分析方法。     

13C and 15N distributions in three spodic dystric cambisols under beech and spruce

The study of natural isotopic abundance signatures is useful to gain further insights in the processes resulting in depthwise changes in the composition of soil organic matter (SOM). Objectives were to describe the delta 13C and delta 15N abundances of SOM with depth in soils from a 153-year old beech (B1), a 119-year old spruce (F1) and a 61-year old spruce (F2) stand at Solling, north-west Germany, and to study, how podzolisation affects the isotopic abundances of 13C and 15N in the SOM. The degree of podzolisation decreased in the order F1 > B1 > F2. At the surface of the humus layer of all three sites, delta 13C values are approximately 1 to 4/1000 higher than in the leaves and needles, probably mainly due to the discrimination of 13C by microbial decomposition. 13C abundances in the organic layers of B1 and F2 increased only slightly from -27.6/1000 PDB (B1, L) to -27.2/1000 PDB (B1, Oh) and from -26.3/1000 PDB (F2, L) to -25.9/1000 PDB (F2, Oh), suggesting that biotic activity resulted in mixing of organic matter. At F1, however, 13C abundance increased from -27.5/1000 PDB (L) to -26.0/1000 PDB (Oh) which reflects the lack of mixing by animals. In the upper 2-4 cm of the mineral soil, i.e., in the eluvial horizons Aeh, 13C values showed a minimum at the spruce sites which was presumably related to a translocation of 13C enriched fulvic acids. Depthwise changes in delta 15N values were not related to podzolisation processes. At all three sites, a 13N enrichment with depth occurred in the mineral soil which is the result of the discrimination of 15N by microbial decomposition.     

Elasticity and inelasticity of the SiC/Al-13Si-9Mg biomorphic metal ceramics

The acoustic investigations of the elastic (Young’s modulus) and microplastic properties of a composite material, the SiC/Al-13Si-9Mg biomorphic metal ceramic, were performed. The ceramic was prepared by infiltration of the Al-13Si-9Mg melt into porous silicon carbide derived from wood of two species of trees, beech and sapele. The measurements were performed with a composite piezoelectric vibrator under resonance conditions, with rod-shaped samples vibrated longitudinally at about 100 kHz over a wide range of vibrational strain amplitudes, which included both the linear (amplitude-independent) and nonlinear (microplastic) regions. It was shown that the Young’s modulus and the microplastic properties of the composite are anisotropic and depend substantially on the tree species, particularly when longitudinal vibrations are excited in samples cut along the tree fibers.     

Slow pyrolysis of wood particles: Characterization of volatiles by Laser-Induced Fluorescence

For a better understanding of the complex processes involved in slow pyrolysis of thermally thick wood particles it is essential to know the composition of the gaseous mixture leaving the pyrolyzing particle. In this work the volatiles in the pyrolysis product gas are characterized by means of in situ Laser-Induced Fluorescence. The results indicate that there are secondary heterogeneous cracking reactions of the primary and secondary tar species occurring in spherical beech wood particles with 25 mm diameter at conversions higher than approximately 0.6 and at heating rates of 0.3 K/s and 0.2 K/s. For pyrolysis of smaller beech wood particles of 0.5–1 mm size complete conversion was achieved without indications of secondary reactions at a heating rate of 0.3 K/s. In order to correctly model the composition of the gas mixture leaving a pyrolyzing wood particle, it may therefore be necessary to consider intra-particle heterogeneous cracking reactions.     

Differential response of two Pinus spp. to avian nitrogen input as revealed by nitrogen isotope analysis for tree rings

Temporal variations in N concentration and δ(15)N value of annual tree rings (1 year of time resolution) of two Japanese Black Pine (Pinus thunbergii) and three Japanese Red Pine (Pinus densiflora) trees under current breeding activity of the Great Cormorant (Pharacrocorax carbo) and the Black-tailed Gull (Larus crassirostris), respectively, in central and northeastern Japan were studied. Both species from control sites where no avian input occurs show negative values (δ(15)N = around -4 ‰ to -2 ‰) which are common among higher plants growing under high rainfall regimes. The δ(15)N values of P. densiflora show uniformly positive values several years before and after the breeding event, indicating N translocation that moved the absorbed N of a given growth year to tree rings of the previous year while a clear historical value of soil N dynamics was kept intact in the annual rings of P. thunbergii. Long-term N trends inferred from tree rings must take into account tree species with limited translocation rates that can retain actual N annual acquisition.     

Nitrogen isotope pattern in Mongolian larch stands at the southern Eurasian boreal forest boundary

ABSTRACT

In the last decades a drastic increase in air temperature but a stable precipitation regime in Mongolia has led to gradual drying conditions. Thus, we evaluated the effect of spatial and climatic characteristics on the soil–plant nitrogen dynamics in three representative larch stands (Larix sibirica) with different geographical and climatic conditions using stable nitrogen isotopes. The results showed significant differences in the soil inorganic N content among sites and consequently a different isotopic composition in the plant–soil system. Litter, bark and wood had the lowest δ¹⁵N values for all sites, slightly higher δ¹⁵N values for needles, while the highest δ¹⁵N values were observed for roots and soil. These differences could be the result of the larch stands age themselves, but were in agreement with the spatial and climatic characteristics of the sites. Based on the δ¹⁵N value a higher reliance on ectomycorrhizal fungi (ECMF) was observed in the warmest and driest site, while lower dependency was shown in the cooler northern site with higher soil inorganic N content. In both sites, the rate of air temperature increase has been similar in the last decades; however, their soil–plant N dynamics showed different characteristics.     

Nickel coated on beech wood by electroless nickel coating: effects of complexing agent concentrations on nickel film properties

In order to obtain beech wood substrates with new functions as conductive materials and to develop their utilities in industrial fields, the technique of electroless nickel coating on the beech wood substrate was employed. The influence of complexing agent concentration [Na₂EDTA·2H₂O] on the nickel surface resistivity was studied. The process conditions were Ni(CH₃COO)₂·4H₂O 0.103?mol/L, CH₃CHOCOOH 18.18?mL/L, N₂H₅OH 54.54?mL/L, NaOH 0.193?mol/L, pH value of 9.5, temperature of 75?°C, and the complexing agent concentration varied between 0.012 and 0.061?mol/L. By means of XRD, EDXRF, and SEM, the chemical composition and morphology of the prepared films were investigated. The results showed that when the complexing agent concentration increased from 0.012 to 0.061?mol/L in the electroless nickel coating baths, the gained nickel mass on the beech wood substrate decreased from 17.04 to 9.03?mg/cm², the nickel crystallite sizes reduced from 16.1 to 1.41?nm and the electric measurements demonstrated that the nickel surface resistivity rose from 0.004 to 192.16?kΩ/cm².     

X-ray micro-computed tomography of beech wood and biomorphic C,SiC and Al/SiC composites

The microstructures of beech wood and of beech wood-derived carbon, silicon carbide (SiC), and an aluminum/SiC composite were studied using both scanning electron microscopy (SEM) and synchrotron X-ray micro-computed tomography (µCT). As opposed to traditional two-dimensional imaging techniques, the µCT data allowed nondestructive evaluation of relatively large sample volumes. Nondestructive three-dimensional data analysis led to the observation of microstructural features, such as varying pore-wall topographies not previously seen in SEM, calculations of the volume fraction of porosity and characterization of the interconnectivity of porosity in the SiC material.     

Microscopic characterization of tension wood cell walls of Japanese beech (Fagus crenata) treated with ionic liquids

Tension wood that is an abnormal part formed in angiosperms has been barely used for wood industry. In this study, to utilize the tension wood effectively by means of liquefaction using ionic liquid, we performed morphological and topochemical determination of the changes in tension wood of Japanese beech (Fagus crenata) during ionic liquid treatment at the cellular level using light microscopy, scanning electron microscopy and confocal Raman microscopy. Ionic liquid treatment induced cell wall swelling in tension wood. Changes in the tissue morphology treated with ionic liquids were different between normal wood and tension wood, moreover the types of ionic liquids. The ionic liquid 1-ethyl-3-methylimidazolium chloride liquefied gelatinous layers rapidly, whereas 1-ethylpyridinium bromide liquefied slowly but delignified selectively. These novel insights into the deconstruction behavior of tension wood cell walls during ionic liquid treatment provide better understanding of the liquefaction mechanism. The obtained knowledge will contribute to development of an effective chemical processing of tension wood using ionic liquids and lead to efficient use of wood resources.     

红木的近红外光谱分析

红木珍贵、种类多,大多数人对红木种类及真伪难以或无法鉴别。利用近红外光谱技术对国家标准中八类红木的近红外光谱进行分析,研究结果表明:(1)近红外光谱与红木色度学参数(L*,a*和b*)之间存在非常高的相关性,预测值与实测红木L*,a*和b*值的相关性分别达到0.988,0.991和0.993;(2)利用化学计量学中的主成分分析(PCA)方法可以将八类红木清楚地区分成八个相应的类别,利用三个主成份信息绘制的三维PCA得分图比二维图更能直观地展现八类红木的区别。研究结果说明应用近红外光谱技术识别红木类别具有可行性,这为开发红木的鉴定或识别提供新的方法和研究思路。     

Stable isotope ratios and uric acid preservation in termites belonging to three feeding habits in Thailand

Nitrogen and carbon stable isotope ratios and uric acid concentrations in termites sampled from a dry evergreen forest in Thailand, were determined across three kinds of feeding habits. Feeding habits of Microcerotermes crassus, which is an abundant wood-feeder, and Dicuspiditermes makhamensis, a common soil-feeding termite, were confirmed by isotopic signatures. Lichen feeding termites (Hospitalitermes birmanicus, H. bicolor and H. ataramensis) were characterized by low delta15N values, suggesting that they assimilated nitrogen deposited from the atmosphere. There was also a significant difference in uric acid concentrations between termites representing different feeding habits. No significant relationships were found between uric acid concentrations and delta15N or delta13C in Hospitalitermes. However, delta15N values were correlated with C/N ratios in H. birmanicus, except in one colony of H. ataramensis. delta13C values in both species were negatively correlated with C/N ratios.