Effect of Continuous Planting on Tree Growth Traits and Growth Stress in Plantation Forests of <i>Eucalyptus urophylla × E. grandis</i>

Continuous planting is the primary method for managing Eucalyptus plantations. The “space-replacing time” approach assesses growth parameters of Eucalyptus trees in China across generations, including height, diameter at breast height (DBH), slenderness ratio, trunk oblateness, and longitudinal growth strain. The findings reveal: (1) significant variations in growth strain occur among generations, with average strain increasing noticeably; and (2) growth-linked traits of Eucalyptus urophylla × E. grandis are impacted, with negative correlation between slenderness ratio and growth strain, and positive correlation between height and trunk oblateness. Factors influencing growth strain include height, slenderness, and surface longitudinal growth strain at breast height, with strong correlations observed. These parameters serve as growth strain indicators. Continuous planting affects growth traits and strain in Eucalyptus plantations. It is advisable to select trees with stable or slow growth rates and to avoid continuous planting without limits

Hydrophobicity and Photocatalytic Activity of a Wood Surface Coated with a Fe³⁺-Doped SiO₂/TiO₂ Film

A Fe3+-doped SiO2/TiO2 composite film (Fe3+-doped STCF) was prepared on a wood surface via a sol&#8315;gel method to improve its photocatalytic activity and hydrophobicity. The structure of the composite film was analyzed by Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity toward degradation of methyl orange and its hydrophobic nature were investigated. The results showed that the composite film was anatase TiO2 crystal form, and the addition of Fe3+ ions and SiO2 enhanced the diffraction peaks for the anatase crystal form. The photocatalytic activity of the wood coated with the composite film was enhanced. The highest degradation percentage was at 1 wt % Fe3+ (40.37%), and the degradation ability of the wood towards methyl orange solution was further improved under acidic conditions. In addition, the composite film was hydrophobic, and the hydrophobic property was enhanced as the immersion time in the sol increased. The wood surface coated with Fe3+-doped STCF exhibited strong hydrophobicity and photocatalytic activity, which could effectively prevent moisture from adhering to the surface and degrade organic pollutants; thus, the modified wood surface had good self-cleaning function

CHEMICAL CONSTITUENT DISTRIBUTION WITHIN MULTILAYERED CELL WALLS OF MOSO BAMBOO FIBER TESTED BY CONFOCAL RAMAN MICROSCOPY

The distribution of cellulose and lignin is key to its physical and mechanical properties of woody materials. This study was carried out to investigate chemical constituent distributrion distribution of Moso bamboo (Phyllostachys pubescens) fiber using confocal Raman microscopy (CRM) with a particular focus on its unique multilayered structure. The results showed that syringyl and guaiacyl units of lignin were widely distributed across the whole cell wall, including the cell corner (CC) and compound middle lamella (CML), whereas p-hydroxyphenyl units were mainly located in CC and CML regions. A series of CRM images of Bbamboo fibewr cell walls confirmed that different concentration of specific chemicals were present in the multilayered structure. Lignin concentration did not always declined from the periphery to the central part but sometimes increased close to lumen edges as well as some layers. Furthermore,  variation of lignin and cellulose concentration across cell wall could be obtained by using the line scanning function. Distribution difference of lignin and cellulose was generally located in CML and lumen side as well as some borders between two adjacent secondary layers. The results from this study will deepen the understanding of the organization of Moso bamboo cell walls

Variation of Chemical Components in Sapwood, Transition Zone, and Heartwood of Dalbergia odorifera and Its Relationship with Heartwood Formation

Heartwood has a high economic value because of its natural durability, beautiful color, special aroma, and richness in active ingredients used in traditional Chinese medicine. However, the mechanism of heartwood formation remains unclear. Dalbergia odorifera was selected as the object of research to analyze this variation in the chemical composition of sapwood, transition zone, and heartwood as well as to elucidate the relationship between this variation and the formation of heartwood. The variation of secondary metabolites was analyzed using gas chromatography-mass spectrometry and ultra-high performance liquid chromatography–mass spectrometry, the variation of lignin was analyzed using Fourier transform infrared spectroscopy and ultraviolet visible spectrophotometry, and the variation law of mineral elements was analyzed using atomic absorption spectrophotometry. The results demonstrated that contents of characteristic secondary metabolites in Dalbergia odorifera were mainly distributed in heartwood (84.3–96.8%), increased from the outer to inner layers of the xylem, and sudden changes occurred in the transition zone (the fourth growth ring). The Dalbergia odorifera lignin can be identified as typical “syringyl–guaiacyl (S–G)” lignin, and the color darkened from the outside to the inside. The results demonstrated that there were more benzene rings and conjugated C=O structures in the heartwood. Additionally, the variation of minerals in the xylem was related to elemental types; the average concentrations of Mg, Ca, Fe and Sr were higher in the heartwood than in the sapwood, whereas the concentrations of K and Zn were higher in the sapwood than in the heartwood owing to the reabsorption of elements. The concentrations of Na and Cu were similar in the heartwood and sapwood. The composition and structural characteristics of secondary metabolites, lignin, and mineral elements in the three typical xylem regions (sapwood, transition zone and heartwood) of Dalbergia odorifera changed. The most abrupt change occurred in the narrow xylem transition zone, which is the key location involved in heartwood formation in Dalbergia odorifera

Tissue Structure Changes of <i>Aquilaria sinensis</i> Xylem after Fungus Induction

In this study, we analyzed the mechanism and the process of fungal-induced agarwood formation in Aquilaria sinensis and studied the functional changes in the xylem structure after the process. The microscopic structure of the white zone, transition zone, agarwood zone, and decay zone of 12-and 18-months of inoculation A. sinensis xylem was studied. The distribution of nuclei, starch grains, soluble sugars, sesquiterpenes, fungal propagules, and mycelium in xylem tissues was investigated by histochemical analysis. The results show that the process of agarwood formation was accompanied by apoptosis of parenchyma cells such as interxylary phloem, xylem rays, and axial parenchyma. Regular changes in the conversion of starch grains to soluble sugars, the production of sesquiterpenoids, and other characteristic components of agarwood in various types of parenchyma cells were also observed. The material transformation was concentrated in the interxylary phloem, providing a structural and material basis for the formation of agarwood. It is the core part of the production of sesquiterpenoids and other characteristic products of agarwood. Compared with the A. sinensis inoculated for 12 months, the xylem of the A. sinensis inoculated for 18 months was more vigorous. There were no significant differences between the 12 and 18 months of inoculation in terms of sugars and agarwood characteristic products. In production, harvesting after 12 months of inoculation can improve harvesting efficiency

Antimicrobial Bamboo Materials Functionalized with ZnO and Graphene Oxide Nanocomposites

Bamboo materials with improved antibacterial performance based on ZnO and graphene oxide (GO) were fabricated by vacuum impregnation and hydrothermal strategies. The Zn2+ ions and GO nanosheets were firstly infiltrated into the bamboo structure, followed by dehydration and crystallization upon hydrothermal treatment, leading to the formation of ZnO/GO nanocomposites anchored in the bulk bamboo. The bamboo composites were characterized by several techniques including scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and X-ray diffraction (XRD), which confirmed the existence of GO and ZnO in the composites. Antibacterial performances of bamboo samples were evaluated by the bacteriostatic circle method. The introduction of ZnO/GO nanocomposites into bamboo yielded ZnO/GO/bamboo materials which exhibited significant antibacterial activity against Escherichia coli (E. coli, Gram-negative) and Bacillus subtilis (B. subtilis, Gram-positive) bacteria and high thermal stability. The antimicrobial bamboo would be expected to be a promising material for the application in the furniture, decoration, and construction industry