Compression combined with steam (CS) treatment is postulated to be an environmentally friendly and efficient modification method to improve the dimensional stability, durability, and mechanical strength of wood. The influences of CS treatment with different radial compression ratios (RCRs) (25% and 50%) and different steam temperatures (140, 160 and 180°C) on chemical components, porosity, and hygroscopicity of earlywood and latewood in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) were investigated respectively on a cellular level by imaging Fourier Transform Infrared (FT-IR) microscopy, Confocal Raman Microscopy (CRM), nitrogen adsorption and dynamic vapor sorption (DVS). The results indicated that the degradation of carbonyl groups of the glucuronic acid component of xylan in earlywood and latewood was mainly responsible for the low hygroscopicity of CS-treated wood. Also, a significant decrease in the amount of C=O and C=C linked to the lignin aromatic skeleton involved in either crosslinking reactions or the degradation reactions could be another contributor to the reduction in wood hygroscopicity. CS-treated wood with a steam temperature of 180°C possessed a lower hygroscopicity that correlated well with the depolymerization of crystalline and amorphous cellulose. A more deformed structure of CS-treated wood led to the formation of greater amounts of mesopores in the cell walls, which could lead to increased degradation of the chemical components of wood cell walls. Furthermore, a higher equilibrium moisture content (EMC) level was found for CS-treated wood with a 50% compression ratio compared to a 25% compression ratio.
Microfibril angle (MFA) is an important ultrastructural feature of the wood cell wall that provides insight into tree growth and wood quality. Unfortunately, it is a property whose value is sensitive to the method of measurement. The aims of this study are to clarify and compare the variation of MFA in Chinese fir [Cunninghamia lanceolata (Lamb.) Hook.] plantation trees by using the pit aperture (PA) and X-ray diffraction (XRD) methods. A decrease in the average MFA from 25° to 12° as determined by PA and from 15° to 9° as determined by XRD was shown from growth ring 2 to ring 26. When measured at various stem heights up to 5.3 m, the MFA decreased from 18° to 15° using PA and from 12° to 9° using XRD. The results show that XRD tended to measure lower MFA values both in the juvenile and mature wood than PA. The majority of within-tree variation in MFA is mainly attributed to the difference between the juvenile and mature wood.
Radial variations in microfibril angle (MFA) and their effect on the mechanical properties of plantation-grown Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) were investigated with the aim of achieving an effective utilization of the wood. Correlations between MFA and mechanical properties, including longitudinal modulus of elasticity (MOEL), static bending strength (MOR) and compression strength parallel-to-the-grain (CS), were analyzed for predicting the quality of timber. The results indicated that MFA had a greater variation in juvenile wood than in mature wood. The biggest change occurred close to the pith in Chinese fir. The outer-rings (rings 9–30 from the pith) have a relatively low MFA, together with high mechanical properties and high density, when compared with the inner-rings (rings 1–8 from the pith). The MFA had significant negative curvilinear correlations with all the mechanical properties (MOEL, MOR and CS) of Chinese fir, with the value of r2 being 0.88, 0.69 and 0.74 respectively. The correlation between the MFA and basic density (BD) was strong in certain consecutive rings (rings 5–30 from the pith), but this did not apply across the whole billet, i.e. from the pith to the bark.
A new species of Moroxylon, M. xinhuaensis Yin, Liu & Cheng, with wood anatomical features found in modern Morus (Moraceae), is described from the Neogene of Xinhua, Yuanmou Basin, Yunnan Province, southwest China. This wood represents the first fossil wood of Morus reported from Asia. It provides additional data for evaluating relationships between the Neogene floras of Europe and eastern Asia.
DNA barcoding technology has emerged as one of the most promising tools available to identify timber at the species level, contributing to the monitoring of the timber trade and the conservation of forestry sources. This paper reviews the progress, challenges, and existing problems in the development of DNA barcoding for wood identification in the last ten years. There is a focus on the optimization of DNA extraction methods for processed or ancient wood, the strategy of screening high-resolution DNA barcodes suitable for wood identification, the development of a wood DNA reference database especially for priority taxa, and the comparison and comprehensive application of sequence analytical methods to achieve accurate identification. In addition to DNA barcoding, the feasibility of other genetic methods for wood identification is also discussed. Furthermore, future research orientation and strategy of wood DNA barcoding are presented. We argue that wood DNA barcoding integrated with other methodologies including wood anatomy can offer an effective approach and a new perspective to promote legal logging for timber trade custody and global biodiversity conservation.
We examined fifty main structural components from fifteen historical wood buildings located in the northern, central, southern and south-eastern regions of Shanxi Province, China and dating from the Tang to the Qing Dynasty. Eleven timber-tree genera were identified: Cupressus, Larix, Malus, Picea, Pinus subg. Diploxylon, Populus, Quercus, Sophora, Sorbus, Ulmus and Zizyphus. Furthermore, wood specimens of Larix and Pinus subg. Diploxylon were determined to species level, viz. Larix gmelinii var. principis-rupprechtii and Pinus tabuliformis, according to their original geographical distribution in this region. Natural distribution of the wood species was apparently the leading criterion for timber selection since most identified genera are native to the areas surrounding the buildings investigated.
We describe a new species, Gleditsioxylon jiangsuensis (Leguminosae), a new record of Robinia zirkelii (Platen) Matten, Gastaldo & Lee (Leguminosae), and a new record of Moroxylon xinhuaensis Yin, Liu & Cheng (Moraceae) from the early Miocene strata of Sihong County in Jiangsu Province, eastern China. Gleditsioxylon jiangsuensis sp. nov. is the first report of Gleditsioxylon fossil wood from China. These fossil woods, combined with paleontological records, may indicate that the boundary between the subtropical and the temperate zones in eastern China during the early Miocene was located north of its modern location.
DNA was isolated from the sapwood, transition wood and heartwood of fresh and dried Cunninghamia lanceolata wood using two DNA extraction protocols: the modified CTAB method and the modified Qiagen kit. Our major objective was to (i) determine an optimized method for retrieving good quality and sufficient quantity of DNA from wood, and to (ii) investigate the effect of different radial positions of fresh and dried wood for DNA extraction. In comparison with the modified CTAB method, a greater quantity of higher quality DNA – both chloroplast and nuclear ribosomal DNA – was retrieved using the Qiagen kit protocol. The chloroplast DNA regions retrieved from both fresh and dried wood were successfully amplified using both protocols, but the PCR amplification for the rDNA-ITS region from the heartwood failed using both protocols. The quantity and purity of the DNA from the sapwood and transition wood (derived from nuclei and plastids in the parenchyma cells) was greater than that from the heartwood (derived mainly from amyloplasts). Due to the influence of the drying treatment, the quantity of DNA decreased by more than 50%. The optimized radial position for DNA extraction in the stem was demonstrated based on anatomical observation.
Pterocarpus santalinus, listed in CITES Appendix II, is an endangered timber species as a result of illegal harvesting due to its high value and commercial demand. The growing demand for P. santalinus and timbers with the morphologically similar Pterocarpus tinctorius has resulted in confusion as well as identification problems. Therefore, it is of vital importance to explore reliable ways to accurately discriminate between P. santalinus and P. tinctorius. In this study, the method of direct analysis in real time and fourier transform ion cyclotron resonance mass spectrometry (DART-FTICR-MS), combined with multivariate statistical analysis, was used to extract chemical information from xylarium wood specimens and to explore the feasibility of distinguishing these two species. Significant differences were observed in their DART-FTICR-MS spectra. Orthogonal partial least square-discriminant analysis (OPLS-DA) showed the highest prediction, with an accuracy of 100%. These findings demonstrate the feasibility of authenticating wood types using DART-FTICR-MS coupled with multivariate statistical analysis.