Objective: The vertical and latitudinal distribution of soil easily-oxidized organic carbon (EOC) in the north subtropical, middle subtropical , and south subtropical regions of Phyllostachys edulis forests were studied to reveal the main influencing factors of its regional differentiation, which provided scientific basis for carbon sequestration, management , and stability of soil organic carbon pool in P. edulis forests. Method: Through field investigation and experimental analysis, the variation rules of soil easily-oxidized organic carbon content along soil layer and latitude was revealed. Factor detection, interaction detection and risk detection of geodetector were used to analyze the factors affecting the regional differentiation of soil easily-oxidized organic carbon. Result: 1) Soil easily-oxidized organic carbon content of P. edulis forests decreases with deepening of soil layers in each region, but its proportion to total soil organic carbon increased with the deepening of soil layer. Easily-oxidized organic carbon contents of 0?60 cm soil layer of northern subtropical P. edulis forests (5.16 g·kg^?1) was higher than that in the middle (4.56 g·kg^?1) and southern (4.86 g·kg^?1) subtropics. The stability of soil carbon pool decreased with decreasing latitude. 2) Mean annual temperature (MAT) was the most important factor in explaining soil easily-oxidized organic carbon of P. edulis forests, with q values ranging from 0.376 to 0.452, followed by elevation (q=0.392, P<0.001). Among the stand factors, the litter thickness had significant effects on soil easily-oxidized organic carbon in different soil layers, and stand biomass of P. edulis had a significant effect on easily-oxidized organic carbon for 30?60 cm soil layer. (q=0.308, P<0.01). 3) The interaction effects between all factors were synergistic. The interaction between stand biomass and litter thickness for 0?10 cm layer was the strongest (q=0.704). The interaction between stand biomass and mean annual temperature was the strongest for 10?30 cm and 30?60 cm soil layers, and the q values were 0.601 and 0.732, respectively. Both of them showing non-linear enhancement. 4) Soil easily-oxidized organic carbon contents was significantly different between different mean annual temperature ranges and was highest at 17?19 ℃ (5.03?12.39 g·kg^?1) and lowest at 15?17 ℃ (2.69?6.20 g·kg^?1). Soil easily-oxidized organic carbon contents was highest in each soil layer at elevation of 700?900 m. The highest easily-oxidized organic carbon contents was reached at a layer of 0?10 cm when stand biomass was 75?90 t·hm^?2. Conclusion: The content of easily-oxidized organic carbon in the soil of the P. edulis forests decreased with the deepening of the soil layer, and its proportion in the total soil organic carbon content showed the latitudinal distribution of north subtropics < middle subtropics < south subtropics. Therefore, forest management with slight disturbance should be implemented in the lower latitudes to reduce soil disturbance and improve the stability of soil organic carbon in the P. edulis forests. Mean annual temperature and elevation were the key factors influencing soil easily-oxidized organic carbon of P. edulis forests. Stand biomass also had significant effects on the easily-oxidized organic carbon in each soil layer and there were significant synergistic effects with climate and topography factors. The single-factor effects of climate, topography, stand condition and their interaction effects together dominated the spatial variation of soil easily-oxidized organic carbon in P. edulis forests at regional level. A scientific basis was provided for the stability of soil active organic carbon and the potential of carbon sequestration.

Objective: Explore the heterogeneity characteristics of soil volumetric water content and spatial in different successional forest communities in typical mid-subtropical regions, including time (annual, wet and dry season) and spatial ( soil layer), and analyze the main factors causing the heterogeneity of soil volumetric water content in different soil layers during the succession process of forest communities, so as to provide data support for regional forest water resources management and forest ecosystem service function assessment. Method: The typical forests in Mopan Mountain, Yuxi, Yunnan, including the Pinus yunnanensis Franch forest (PF) in the pioneer stage of succession, P. yunnanensis broadleaf mixed forest (PBMF) in the mid-succession stage and the evergreen broadleaf forest (EBF) as climax community, the were selected by using time-domain reflectometry and classical statistical menthods. From May 2021 to April 2022, the soil volumetric moisture content for each 10 cm soil layer within 0?60 cm of the sample plot was measured to explore the spatio-temporal heterogeneity and influencing factors of forest soil moisture. Result: 1) In the mid-subtropical region with distinct climatic dry and wet and frequent droughts, the water storage of forest soil showed moderate variation in time and was consistent with the trend of precipitation. With the succession, the mean annual soil volumetric water storage was the highest in EBF, followed by PBMF, and the lowest in PF. The soil water storage of EBF and PBMF increased by an average of 31.24% and 15.22% respectively compared to PF throughout the year. 2) The soil volumetric water content of forests in three succession stages increases with the thickening of soil layers. The average soil volumetric water content in the 0?10 cm soil layer is 45.22% lower than that in the 50?60 cm soil layer. The coefficient of variation of soil volumetric water content is significantly negatively correlated with soil volumetric water content (P<0.05). 3) The soil volumetric water content is significantly negatively correlated with forest density, tree height, and soil sand content (P<0.01), there is a highly significant positive correlation with leaf area index, canopy density, soil porosity, clay content, silt content, organic matter content, and organic carbon content (P<0.01). The correlation between soil volumetric water content and leaf area index, soil porosity, silt content, organic matter content, and organic carbon content is the closest. Conclusion: The mean coefficients of variation of soil volumetric water content in the year, dry and wet seasons and 0?60 cm soil layers of forests at different succession stages in Yuxi Mopan Mountain, Yunnan Province were 19.86%, 17.31%, 14.06%, and 20.58%, respectively, showing moderate heterogeneity, and the water storage capacity of forest soil increased with succession, showing moderate heterogeneity, and the water storage capacity of forest soil increased with succession. Leaf area index, soil porosity, grit content, organic matter content, and origin carbon content were the dominant factors that contribute to the spatial heterogeneity of soil volumetric moisture content in different soil layers.

Objective: This study aims to investigate the effect of clumping index (CI) and maximum carboxylation rate (V_cmax) from remote sensing products on estimation of vegetation productivity with the boreal ecosystem productivity simulator (BEPS) model. Method: The FLUXNET and ChinaFLUX data were used to analyze the sensitivities of CI and V_cmax in BEPS model, and compare the effects of CI and V_cmax on Gross Primary Productivity (GPP) estimation. On this basis, the vegetation productivity of terrestrial ecosystems in China in 2012 was estimated. By comparing with the estimated results of the default value, we determined the impact of the spatio-temporal changes of CI and V_cmax on the model performance. Result: 1) The results showed that CI and V_cmax had high sensitivities in the BEPS model. They were positively correlated with vegetation productivity, and the sensitivity of V_cmax was higher than that of CI in different vegetation types. 2) When CI and V_cmax remote sensing products (NDHD-CI and SIF-V_cmax) were used simultaneously, the simulation results had the smallest error and the highest accuracy. The root mean square error (RMSE) of GPP decreased from 665.60 g·m^?2a^?1 to 584.71 g·m^?2a^?1, and the mean absolute error (MAE) and mean relative error (MRE) were the lowest in the four simulation cases. 3) In 2012, the total GPP and Net Primary Productivity (NPP) of terrestrial ecosystems in China were 5.21 Pg·a^?1 and 2.49 Pg·a^?1, respectively. Affected by the spatio-temporal dynamics in the CI and V_cmax, the GPP and NPP estimates were 3.06% and 4.72% lower than the default results of the model, respectively. Conclusion: Our results have demonstrated that NDHD-CI and SIF-V_cmax can improve the accuracy of BEPS models in estimating vegetation productivity, and other high-sensitivity parameters and model mechanisms can be optimized and improved in the future. Affected by the temporal and spatial changes of CI and V_cmax, the estimation results of vegetation productivity are slightly lower than the default situation. The effect of V_cmax on vegetation productivity estimation is higher than that of CI.

Objective: This study aims to explore the impact of neighboring tree species diversity on element stoichiometry in subtropical forest ecosystems, in order to provide scientific basis for nutrient utilization efficiency in the selection of afforestation tree species in subtropical regions. Method: Based on tree diversity and a large-scale ecosystem function experimental platform, plots with different tree species richness (1, 4, 8, 16, 32) were selected, with Chinese fir (Cunninghamia lanceolata) as the target tree species, and 8 target trees were selected in the central area of each plot. The nutrient concentration of nitrogen (N), potassium (K), calcium (Ca) and magnesium (Mg) in leaves were measured, and the dissimilarities of functional traits between its neighbors were calculated. Linear mixed-effect models were used to study the effects of neighbor tree species richness, functional trait dissimilarities among tree species, and neighbor tree height index on the stoichiometric ratios of N∶K, N∶Ca and N∶Mg in target tree leaves. Result: 1) High dissimilarities in specific leaf areas between the target tree and its neighbor trees significantly reduced the ratios of N∶K and N∶Mg of the target tree's leaves, but did not affect the N∶Ca. 2) The species richness of neighbor trees increased N∶Mg of the leaves of the target trees. 3) The neighbor tree height index (shading effect) significantly reduced the N∶Ca ratio of the target tree leaves. As the shading increased, the effect of dissimilarity in root tissue density between Chinese fir and neighboring trees on the N∶Ca ratio in Chinese fir leaves shifted from positive to negative. Conclusion: Establishment of mixed forests in subtropical regions is beneficial for increasing the functional trait dissimilarities between neighboring tree species, enhancing the utilization of calcium, magnesium, and potassium nutrient resources, and improving the nutrient balance of Chinese fir.

Objective: Quercus palustris is mainly propagated by seeds, but its seeds are sensitive to dehydration, belonging to recalcitrant seeds. Consequently, water loss is an influential factor affecting its seed storage and transportation. This study aims to explore the dynamic movement pattern of water during the water loss process in Q. palustris seeds, in order to provide a theoretical basis for safe transportation and storage of Q. palustris seeds. Method: In this study, the seed water content was reduced by the natural drying method. Magnetic Resonance Imaging (MRI) technology was utilized to analyze the movement path of water in seeds during dehydration and combined with Signal-to-Noise ratio (SNR) to quantitatively analyze the water loss in each part of seeds during the water loss process. Result: 1) The results of high-field MRI and SNR analysis showed that the water content in the radicle region and central part of cotyledons of fresh Q. palustris seeds was higher, while the water content in peripheral parts of cotyledons was relatively lower. The SNR of different tissues, cotyledons and seed coats were different. 2) When the water content of seeds decreased to 30.0%, water content in the radicle region dropped significantly, with the water loss rate of the radicle being the fastest. Meanwhile, the water loss rate of cotyledon periphery also decreased, while the water of cotyledon center did not change significantly, and its water loss rate was the slowest. Additionally, the water loss rate in different parts of seed coat was also different. When the water content continued to drop to 25.0%, the germination percentage of seeds decreased significantly. At this time, the water in radicle region was almost invisible, with a large part of cotyledon below the radicle beginning to turn dark. As the SNR of radicle region fell sharply again, the SNR of three seed coat parts was reduced to a very low level, among which, the SNR of seed chalaza decreased the most, and the chalaza shrank due to water loss. When water content was reduced to 10.0%, the cotyledon shrank obviously, with only a small amount of water remaining in the central part of cotyledon and a small part below it. Conclusion: The important water storage sites of Q. palustris seeds are the radicle region and the cotyledon center. During the water loss process, the water loss rate of radicle is the fastest, while the water loss rate of the cotyledon center is the slowest. The water loss in radicle is a critical factor causing seed quality to decline.

Objective: This study aims to investigate the effects of different pruning intensities on the formation and quality of clear wood of Cunninghamia lanceolata, in order to provide a scientific basis for guiding the cultivation of large-diameter-class, high-quality clear wood of C. lanceolata with reasonable pruning intensity. Method: With a randomized block design, an experiment was implemented in that a 4-year-old C. lanceolata plantation that was subjected to different pruning intensities (i.e. the trees were pruned annually until their stems with a diameter of 6 cm, 8 cm, 10 cm, and 12 cm, respectively, and the pruning was stopped when the pruning clear bole height of stems reached 7 m, with the unpruned trees served as the control). After 22 years of pruning, the growth of the trees was investigated. A total of 30 average standard trees from different pruning intensities were selected and cut down, and the stems below 7 m were cut off and carried back to the laboratory for the determination of plumpness of the stems. The number, long diameter, and short diameter of knots were measured after the stems were cut according to the saw-cutting method and rotary cutting method, and the ratios of clear wood volume, knot-free veneer quantity, and knot volume were counted. Result: The diameter at breast height (DBH) and individual volume showed a significant decrease trend with increasing pruning intensity, but pruning intensity had no significant effect on tree height. The DBH with a pruning intensity of 6 cm was significantly smaller than that with other treatments, and the individual volume was significantly smaller than that with the pruning intensities of 10 cm and 12 cm, and of the control (CK). The DBH with a pruning intensity of 8 cm was significantly smaller than that with pruning intensities of 10 cm and 12 cm, and the individual volume was significantly smaller than that with a pruning intensity of 12 cm. In the 1.3–4 m cut logs, the plumpness with a pruning intensity of 6 cm was significantly higher than that with pruning intensities of 10 cm and 12 cm. In the 4–7 m cut logs, the plumpness with a pruning intensity of 8 cm was significantly higher than that with a pruning intensity of 10 cm. The determination results of the saw-cutting method showed a significant decrease trend of the number of knots with the increasing pruning intensity, and both the long and short diameters of knots decreased with increasing pruning intensity, and the short diameter of knots with a pruning intensity of 6 cm was significantly shorted than that with the other treatments. According to the determination results of the rotary cutting method, the number, long diameter, and short diameter of knots all tended to decrease significantly with the increasing pruning intensity. The ratio of both clear wood volume and the ratio of knot-free veneer quantity tended to significantly increase with increasing pruning intensity, while the ratio of knot volume tended to significantly decrease with increasing pruning intensity. Compared with the control, the ratio of clear wood volume with four pruning intensities were significantly higher (at least 51.1%), and the ratio of knot-free veneer quantity were significantly higher (at least 33.25%). The determination results of both the saw-cutting method and rotary cutting method consistently suggested that with pruning intensities of 6 cm and 8 cm had fewer and smaller distribution of knots, and the ratio of clear wood was more obviously improved. The pruning effect was ranked as pruning intensities of 6 cm>8 cm>10 cm>12 cm>CK. Conclusion: The selection of pruning intensity depends on the management objective. If greater DBH, tree height, and individual volume are desired, without demand of wood quality, pruning intensities of 10 cm and 12 cm can be good choice. If higher stem plumpness and ratios of clear wood volume and knot-free veneer quantity, lower ratio of knot volume, fewer number of knots, and smaller long and short diameters of knots are required, without demand of the amount of growth, pruning intensities of 6 cm and 8 cm can be selected.

Objective: Studying the impact of root exudation of Carya cathayensis (REC) on the growth and phosphorus (P) activation ability of exogenous phosphorus solubilizing bacteria in C. cathayensis is beneficial for further understanding the interaction between microorganisms and plants, and provides effective ways and scientific basis for alleviating P limitation in C. cathayensis forests. Method: The liquid shake flask and soil culture experiments were conducted to study the effects of REC on the growth, reproduction, and P mobilization of two strains (Lysobacter enzymogenes CQ18 and Paenibacillus polymyxa QP22) that can mineralize organic P components. Result: The results showed that application of REC had no significant effect on the growth of strain CQ18 in liquid culture, but promoted the reproduction of strain QP22. After inoculation in the liquid culture medium with lecithin as the sole P source, the acid, neutral, and alkaline phosphatase activities significantly enhanced; the soluble P concentration showed a trend of increase followed by a decrease and was significantly higher than that of the uninoculated treatment. Among the treatments inoculated with strain CQ18, the average soluble P concentration of the treatment at low level of REC was the highest (41.93 mg·L^?1), while the treatment without REC was the lowest (37.01 mg·L^?1). Among the treatments inoculated with strain QP22, the average soluble P concentration of the treatment in middle level of REC was the highest (30.14 mg·L^?1), and the high concentration REC treatment was the lowest (18.09 mg·L^?1). The number of strains, soil available P content and acid phosphatase activity in the inoculated soil showed a trend of increase followed by a decrease, while were all higher than those in the non-inoculated soil. At harvest, the number of tested strains in soils and soil acid phosphatase activity of treatments containing REC were higher than those in the treatment without REC, but there was no significant difference in soil avaliable P content between them. Conclusion: Phosphatases could be of utmost importance in the mineralization of the organic P by strains of CQ18 and QP22, and REC could promote, their growth and P mobilization. Therefore, strains of CQ18 and QP22 are potential to be used as biofertilizer in Carya cathayensis forests.

Objective: This study aims to reveal the changes of Pinus yunnanensis seedling growth and non-structural carbohydrates (NSC) in response to persistent drought stress, in order to provide theoretical support for the population dynamics of this species and the formulation of rational management measures, as well as a basis for plantation establishment, especially seedling management, under drought conditions. Method: A pot experiment was carried out on 2-year-old P. yunnanensis seedlings, and a weighed water control method was used to control the relative soil water content at 75%–85% (control), 60%–70% (mild drought), 45%–55% (moderate drought) and 30%–40% (severe drought) of the field water holding capacity to study the effects of different drought treatments on seedling ground diameter, seedling height, biomass accumulation and distribution and NSC content. Result: 1) The seedling ground diameter and seedling height growth, needles, stems, coarse roots and whole plant biomass all gradually decreased with increasing soil drought. However, fine root biomass gradually increased, with a significant increase of 22.79% under severe drought. 2) The NSC content of seedling needles, stems and crude roots all increased to different degrees with increasing soil climate, with significant increases of 10.89%, 45.37% and 30.70% under severe drought, respectively, while the NSC content of fine roots decreased to different degrees. There was difference in the ratio of soluble sugars to starch in various organs in response to drought stress, and the ratios were all greater than 1. Starch was the most important form of NSC storage in P. yunnanensis seedlings, mainly in stems and thick roots. 3) Under drought stress, the biomass and NSC organ allocation ratios of P. yunnanensis seedlings changed in a similar pattern, i.e. the biomass and NSC allocation ratios of leaves gradually decreased with increasing soil drought, those of stems and fine roots gradually increased, and those of coarse roots first decreased and then increased. 4) Seedling growth was generally significantly correlated with non-structural carbohydrates. Plasticity and PCA analyses showed that the plasticity indices for seedling height and ground diameter were relatively small, while the plasticity indices for needle biomass, fine root biomass ratio, stem starch, needle and stem soluble sugars/starch were higher and the load on the principal components was greater. Conclusion: Drought stress significantly inhibits the growth of P. yunnanensis seedlings. When carbon availability is limited by drought stress, there is a trade-off between growth and NSC storage, i.e. biomass and NSC are allocated less to needles but more to fine roots, which is an important cause of slow growth in P. yunnanensis seedlings. P. yunnanensis seedlings adapt to drought conditions mainly by regulating needle and fine root growth, increasing storage of starch in stems, and maintaining a dynamic balance of NSC in needles and stems.

Objective: With the rare ornamental tree species Michelia chapensis in southern China as research material, this study aims to investigate the flowering and pollination biology under ex situ protection, and provide technical guidance for effective protection and hybrid breeding. Method: Floral morphology and flowering process were observed, pollen viability was measured by TTC method, and the acceptability of stigma was determined by benzidine-hydrogen peroxide. The type of M. chapensis breeding system was analyzed based on the estimated utcrossing index (OCI) and pollen-ovule ratio (P/O), as well as the results of artificial pollination and pollination media observation. Result: The flowering period of M. chapensis was from mid-late March to early and mid April, with the single flowering period for 7–12 days, and the single flowers exhibited a phenomenon of two-time opening-closure flowering. The opening time of individual plant lasted about 6–20 days. M. chapensis showed dichogamy and protogyny in its flowering process, the stigma had the strongest receptivity on the day of flowering, and the pollen had the strongest vitality in the second day of flowering. The outcrossing index was 4 and its pollen-ovule ratio was 557.18±46.23. The artificial pollination revealed the autonomous self-pollination phenomenon did not exist and had no apomixis phenomenon. The fruit-setting rate of artificial pollination was significantly higher than that of natural pollination. The breeding system was facultative outcrossing with partial self-compatibility, and required pollinators in the pollination process. Conclusion: M. chapensis has the characteristic of insect pollination according to the morphology and flowering dynamics. Its two-time opening-closure flowering phenomenon separates the maturity time of the female from male stamens, which ensures its cross pollination. The pollination process requires a pollinator.

Objective: AGAMOUS (AG) plays an important role in controlling the development of pistil and stamen. The cloning and functional analysis of AG homologous gene is helpful to clarify the function of AG gene in the flower organ development of Rhus chinensis, and lays a foundation for further exploration of the gender differentiation mechanism of R. chinensis flowers. Method: Based on existing transcriptome data in this laboratory, and combined with RACE technology, an AG homologous gene was cloned from R. chinensis flowers, and the structure and phylogenetic evolution of its encoded protein were analyzed. The real-time quantitative PCR was used to analyze the expression characteristics of AG homologous gene of R. chinensis in female, male and bisexual flowers at different flowering stages. Furthermore, the overexpression vector of AG homologous gene of R. chinensis was constructed, the transgenic plants was obtained by inflorescence staining and the transgenic plant phenotype was observed. Result: Two alternative splicing transcripts of AG homologous gene were cloned from R. chinensis, namely RcAG and Rcag with the deletion of the sixth exon. RcAG contains 729 bp open reading frame and can encode 242 amino acids. Rcag contains 687 bp open reading frame, encoding 228 amino acids. Phylogenetic tree analysis showed that RcAG was closely related to AG homologous proteins of Mangifera indica and Pistacia vera. qRT-PCR analysis showed that the abundance of RcAG and Rcag in female, male and bisexual flowers of R. chinensis showed a continuously increasing trend at different developmental stages, and the abundance of RcAG and Rcag in male flowers was significantly higher than that in female and bisexual flowers. Phenotypic observation of Arabidopsis thaliana showed that overexpression of RcAG in A. thaliana resulted in loss of petals and stamens, stigmatization of the tip of the sepal, and ovular structure at the edge of the base of the sepal. However, the number of petals increased and the number of stamens decreased in Rcag transgenic Arabidopsis. Conclusion: Based on the above results, Rcag loses the normal function of AG gene probably due to the absence of 42 bp base in K-region, and competes with RcAG to jointly regulate the development of female and stamen of R. chinensis. These results lay a foundation for the further exploration of RcAG and Rcag in the sex differentiation of R. chinensis.

Objective: Nematus is the first established genus in the Nematinae (Tenthredinidae), and its morphological classification is very complicated and difficult. This study aims to determine the taxonomic status of the questionable species within the genus. Method: Two species of Nematus were collected from Salix paraplesia var. subintegra in the courtyard of Forestry and Grassland Bureau of the Xizang Autonomous Region and Salix matsudana in Zhalantun, Hulunbeier, Inner Mongolia, respectively. Traditional morphological classification methods were used to identify the species. The mitochondrial genome of the two species were re-sequenced using Illumina Hiseq 4,000 platform by following the standard protocols. The assembled and annotated mitochondrial genomes were analyzed based on alignment and secondary structure. Result: The two species were identified as N. trochanteratus (Malaise, 1931) and N. hequensis Xiao, 1990. The mitochondrial genomes of N. trochanteratus and N. hequensis were 16337 bp and 16126 bp long, respectively. The comparison between the two showed that the consistency was as high as 98.02%, with 17 gene sequences completely identical, and the other 20 gene sequences showing only minor differences. There were differences in 8 base sites of six tRNAs between the two species, four sites in 12S rRNA, and seven sites in 16S rRNA. Among the 13 protein coding genes, COI, ND2 and ND4L had the largest genetic distance (K2P) of 0.011, and ATP8 had the Minimum genetic distance of 0. Conclusion: Based on the morphological and mitochondrial genome difference analyses of the two species, it has been confirmed that they are synonymous. According to the International Code of Animal Nomenclature, N. hequensis is identified as the secondary synonym of N. trochanteratus.

Objective: In this study, the influence of polyvinyl alcohol/lithium aluminum hydrotalcite (PVA/LDH) dispersion on the physical and chemical properties of Balsa wood processing residues was investigated, which provided theoretical basis for constructing high performance wood - based composite materials, contributing to realize the high-value utilization of wood processing residues. Method: Inspired by the hierarchical“brick and mortar”structure of natural nacre, the Balsa wood processing residues (wood powders) were used as the main raw materials to obtain the 2,2,6,6-tetramethylpiperidine-1-oxylradi-cal (TEMPO)-functionalized wood powders (T-WP) through the delignification and oxidation modification process. Then, different proportions of PVA/LDH dispersion was added into the T-WP and a noval high-performance wood-based lamellar composites with natural organic polymers and inorganic nanosheets were assembled by intercalating inorganic LDH nanosheets through the vacuum filtration self-assembly process. What’s more, the FTIR, XPS, Zeta-potential and mechanical properties were tested and analyzed to investigate the interface interactions between the components and the synergistic enhancement mechanism of mechanical properties. Result: 1) When the particle size of wood powder was 100 mesh, the pure T-WP film showed optimal tensile strength of (225.25±0.82) MPa and toughness of (5.18±0.36) MJ·m^?3, respectively. 2) The PVA/LDH nanosheets were successfully intercalated on T-WP and formed hydrogen bonds, electrostatic interactions and covalent crosslinking with oxygen-containing functional groups on T-WP molecular chains. 3) The mechanical properties of T-WP-PVA/LDH films with different PVA/LDH contents were analyzed, which illustrated that the T-WP-PVA/LDH film reached the optimal mechanical properties with 20 wt% PVA/LDH, for example, the tensile strength and Young’s modulus reached up to (287.29±4.91) MP and (14.21±2.60) GPa, which were 1.28 and 2.40 times that of pure T-WP film, respectively. 4) Under the condition of 90% relative humidity and 25 ℃ for 16 h, the hygroscopic rate and the tensile strength of the as-prepared T-WP-PVA/LDH film were 45.43% and 105.40 MPa; in moist soil, the T-WP-PVA/LDH film exhibited excellent biodegradability. Conclusion: For T-WP-PVA/LDH bioinspired layered composites, the active oxygen-containing functional groups on T-WP molecular chains formed hydrogen bonding, electrostatic interactions and Al-O-C covalent cross-linking with PVA/LDH dispersion, establishing a synergetically reinforced biomaterials system, which remarkably enhanced the mechanical properties of T-WP-PVA/LDH films. Furthermore, these charming characteristics endowed the as-prepared wood-based layered composites with extensive application prospect in packings, mulching films and throw-away lunchboxs, which was expected to replace petroleum-based products such as polyethylene and polypropylene.

Objective: Aiming at the poor permeability of formaldehyde-free adhesive in the paper interlayers as well as the covering the original paper colour and texture to some extent, To reduce the influence of formaldehyde-free adhesive on surface patterns of decorative paper, and also to provide a suitable method for the preparation of formaldehyde-free decorative paper, originated from the performance of decorative raw paper, the combination of intra-pulp filler filling and surface pigmented coating to treat the decorative raw paper was adopted., which aimed to improve the printing suitability and covering power of the paper under the prerequisite of guaranteeing the paper's permeability and absorption of the adhesive solution. Method: In this experiment, high-quality hardwood pulp and softwood pulp were selected for papermaking. The content of filler (TiO₂) in the pulp was set to three gradients of 20%, 30% and 40%, then the mixture of silicon dioxide (SiO₂) and polyvinyl alcohol (PVA) to coat theses base paper were used. After calendaring, the coated decorative base paper was obtained. The decorative base paper was impregnated with aldehyde-free adhesive, after hot pressing and veneering to obtain the decorated wood-based panels. The surface state and dynamic permeability of the decorative base paper were characterized and tested using scanning electron microscopy (SEM) and dynamic penetration analyzer, respectively. Inkjet printer was used to print in order to analyze the printing performance of the decorative base paper by the Spectrophotometer combined with the calculation of the relative contrast. The physical properties such as tensile strength, smoothness, air permeability, water absorption and whiteness of decorative base paper and the surface wear resistance, surface hardness and surface bonding strength of decorated wood-based panels are tested and analyzed. Result: The more pores of the base paper were filled with the amount of filler increasing, which would affect the permeability of the adhesives inside the paper. On the other hand, the dense surface coating would also reduce the permeability of the adhesives inside the paper to a certain extent. The color density of uncoated base paper declined with the increase of pulp filling, the density of green, magenta, yellow and black of coated base paper increased by 69.0%, 96.2%, 45.6% and 86.5% compared with that uncoated base paper respectively. The relative contrast of magenta, yellow and black reached the standard requirements. Coating can play a positive role in the printing suitability of decorative base paper, but the change of filling amount has no significant effect on the printing suitability of decorative base paper coated; With the increase of filling amount, the tensile strength and water absorption of decorative base paper decreased, and the smoothness, apparent density and whiteness increased. The tensile strength and smoothness of coated decorative base paper increased by 52.8% and 97.56% compared with that of uncoated decorative base paper, but the whiteness did not significantly change and a slight increase in opacity. The surface wear resistance, hardness and surface bonding strength of the coated aldehyde-free impregnated paper after hot pressing meet the standard requirements. Conclusion: Reducing the filling amount of decorative base paper pulp with surface coating, can improve the physical properties of decorative base paper and printing suitability. The decorative base paper produced in this way is suitable for the impregnation of non-formaldehyde adhesive, which is conducive to the development of non-formaldehyde development of decorative paper.

Objective: With soybean meal (SM) as the main raw material, the double cross-linked network structure was constructed to improve the water-resistant bonding performance and the toughness of the cured adhesive layer of SM adhesive, which provided theoretical basis and technical guidance for the industrial application of soybean meal adhesive. Method: Epoxidized natural rubber (ER) and glycerol triglycidyl ether (PTGE) were used to construct a double cross-linked network structure in soybean meal adhesive system. The effects of ER with different epoxy values on the chemical composition, viscosity, moisture uptake, residual rate, thermal stability, and cross-section morphology of modified SM adhesive were studied, and the wet shear strength of the prepared poplar plywood was characterized. Result: 1) ER-50 with 50% epoxy value and PTGE (epoxy crosslinking agent) were used to modify SM adhesive. The wet shear strength of the modified SM adhesive (SMP/ER-50) was 1.02 MPa, which was 292.3% higher than that of the control group and reached the national standard of class II poplar plywood. 2) It was observed by scanning electron microscope that the cross-section of the cured adhesive layer of SMP/ER-50 adhesive appeared to have a uniform phase separation structure, which effectively improved the toughness of the adhesive. 3) SMP/ER-50 adhesive had excellent water resistance, and its residual rate was 90.54%, which was 26.65% higher than that of the control group. The moisture uptake was 19.28%, which was 14.99% lower than that of the control group. Conclusion: The main reason for the improvement of water resistance and toughness of SMP/ER-50 adhesive was that PTGE and ER-50 formed a dense double cross-linking network structure in the adhesive system, which prevented water immersion and improved the water resistance of SMP/ER-50 adhesive. In the double cross-linking network, ER absorbs part of the stress and dissipates the energy when subjected to external force, thus achieving the toughening and strengthening of the SMP/ER-50 adhesive.

Objective: The objective of this study is to investigate the impact of structural parameters of a wood spray nozzle on nozzle speed (v₂), paint mist diffusion angle (γ), and paint mist uniformity (λ), and to determine the optimal structural parameters for improving spraying efficiency and effectiveness in wood spraying. Method: Using the theory of droplet collision, aggregation, and accumulation, we examined the factors influencing nozzle speed (v₂), paint mist diffusion angle (γ), and paint mist uniformity (λ). The seven key internal structural parameters of the original nozzle, including inner wall chamfering angle (β), length of three pipelines (L₁?L₃), and diameters of three pipelines (d₁?d₃), were chosen as optimization parameters. A 7-factor, 3-level, 3-index Box-Behnken design (BBD) response surface test was designed using Design Expert software. The significance of each structural parameter on nozzle speed, paint mist diffusion angle, and paint mist uniformity was determined. The BBD test results were obtained through a three-part simulation: internal flow field simulation of the nozzle using the k-ε model, high-pressure flat mouth atomization simulation using the KHRT model, and determination of paint mist diffusion angle using Image J and Python were used to calibrate the uniformity of atomization simulation results using the“droplet spreading method”. The optimal structural parameters were obtained through multi-objective optimization, and the spraying effect was validated through simulation and actual spraying. Result: The BBD response surface test results showed that the influence of the seven key internal structural parameters on the indexes was complex, but the regression of nozzle speed (v₂), paint mist diffusion angle (γ), and paint mist uniformity (λ) was statistically significant (P≤0.000 1). The theoretical optimal paint spray diffusion angle under multi-objective optimization was determined to be 21.28°, and the optimal uniformity was 3.053. The simulation of the optimal spray nozzle showed an increase in nozzle speed from 35.8 m·s^?1 to 107 m·s^?1, paint mist diffusion angle (γ) from 16.74° to 21.09° (0.883% difference from theory), and paint mist uniformity (λ) from 3.62 to 3.03 (0.751% difference from theory). In the wood spraying test, the standard deviation of paint thickness on wood specimens was reduced from 21.71 μm to 17.74 μm after optimization. Additionally, the spraying time on one side decreased from 6.2 s to 5.5 s, and the travel distance of the spray nozzle on one side decreased from 3 255 mm to 2 887 mm. Conclusion: The “droplet spreading method” and the optimization of nozzle structure parameters using response surface methodology (RSM) and multi-objective techniques can provide guidance for the optimal design of wood spray nozzles. This approach effectively improves the uniformity and efficiency of wood spraying.

Objective: In order to evaluate the durability of wood treated by cyproconazole (Cy), cupraamine/ammonia/Cy (CuCy) and epoxiconazole (EPO) formulations, the suitable retention of the above formulations for exterior ground contact circumstance (C4.1) was determined for national standard and its practical application. Method: The water soluble micro-emulsions of Cy as well as EPO were prepared and impregnated into masson pine and radiata pine through vacuum pressure process. According to the national standard《Method of evaluating wood preservatives by field tests with stakes》(GB/T 27655—2011), the decay and termite resistance index of cyproconazole, CuCy and epoxiconazole treated masson pine and radiata pine was calculated and the natural durability was conducted and determined. Result: At Beijing field test site, located in medium biological hazard zone (Z2), the decay resistance index of all Cy and EPO treated wood with retention above 0.049 kg·m^?3 was above 9.0 after 7 years. The decay resistance index of all CuCy treated pines was 10 after 11 years, while the retention was 1.60-3.20 kg·m^?3 for masson pine, and the retention was 1.40-3.04 kg·m^?3 for the radiata pine. The decay resistance of CuCy treated wood was excellent and was equivalent to that of cupraamine/ammonia/tebuconazole/propiconazole (CuPT) treated wood with the same retention at Beijing test site. For all the masson pine treated by CuCy at Guangzhou test site, located in severe biological hazard zone (Z4), the decay resistance index was above 9.78 at the retention 1.97-2.80 kg·m^?3, and the termite resistance index was 7.15 at the retention of 2.80 kg·m^?3 after 11 years. Conclusion: The results showed that the CuCy treated wood with retention above 1.60 kg·m^?3 performed excellent protection for decay under the usage C4.1 in Z2, while CuCy treated wood with retention above 2.80 kg·m^?3 performed good protection for both decay and termite in Z4. The decay resistance of Cy and EPO treated wood was more efficient than that of tebuconazole and propiconazole in Z2, while the durability of wood treated by CuCy was equivalent to that treated by CuPT at the same retention in both Z2 and Z4.

Objective: Against the backdrop of ecological civilization construction, changes and influencing factors of total factor productivity of forestry in underdeveloped and ecologically vulnerable areas were studied. The feasible paths to improve the total factor productivity of forestry were explored from the forestry resource investment and allocation, the production and operation scale adjustment and other perspectives. Thus, it provided scientific basis and theoretical support to accelerate in transforming forestry development mode and formulating the policies that contribute to the high-quality forestry development in homogeneous alpine collective forest area where ecological vulnerability and economic poverty overlap. Method: A DEA-Malmquist model was established with fund, land and labor as input factors and economic, ecological and social benefits as output factors on the basis of the tracking investigation data of 500 peasant households in Gansu Province from 2009 to 2018. A panel Tobit model was constructed by selecting 13 variables out of 6 dimensions comprising householder characteristics, family characteristics, woodland characteristics, location characteristics, forestry policies and forestry services. Thus, the total factor productivity of forestry in Gansu Province was measured and calculated and its influencing factors were analyzed. Result: 1) From the perspective of holistic change, the growth in total factor productivity of forestry is insufficient, and the reason is that each component has not developed into synergy. Specifically, the growth in total factor productivity of forestry is driven by technology advancement while technological efficiency, pure technological efficiency and scale efficiency have presented only limited promotion effects. 2) From the perspective of temporal characteristics, the total factor productivity of forestry is in an unstable state (presenting alternating up-and-down fluctuations from 2010 to 2018) and a sustainable development in forestry productivity remains unfulfilled. 3) From the perspective of regional characteristics, the total factor productivity of forestry presents obvious region-based differences due to the differences in both natural and historical conditions, and economic and social advancement. By region, the growth in total factor productivity of forestry is insufficient in eastern Gansu, limited in southern Gansu and fast in middle Gansu. By county territory, there is a great difference among counties in southern Gansu, followed by middle Gansu and the least in eastern Gansu. 4) From the perspective of influencing factors, the total factor productivity of forestry is subject to the following factors, including age, cadre number, migrant worker headcount, proportion of forestry income to total income, extent where forest road meets the need, geographical location, difficulty in lumbering index application, access to forestry subsidy, participation in forest insurance, the difficulty in forest right mortgage loan and participation in forest cooperative society. Conclusion: 1) High value should be put to the basic research on forestry theories, the constant transformation and application of scientific and technological achievements in forestry and the reliance on scientific and technological progress so as to ensure the sustainable development in forestry. 2) The training measures of forestry should be strengthened, and the efficiency of forestry technology should be improved. Attention should be paid to the effect of forestry technology, and the development mode of forestry should be shifted. 3) The financing supply for forestry should be increased, and the standardized forest land circulation should be guided. The socialized service system of forestry should be completed, and the scale efficiency of forestry should be promoted so as to realize its scale economy. 4) Technological progress should be improved continuously, and technical efficiency should be boosted gradually. Sscale potential should be tapped fully so as to prompt all productivity component to form synergy; the production factors of forestry should be allocated rationally and effectively. 5) Forestry development among various areas should allow for the particularity of their own forestry resource endowment and the necessity and difficulty in ecological security. The targeted support policies should be provided to develop forestry based on local conditions; regional exchange and cooperation should be enhanced to facilitate regional common development.