Objective: This study aims to explore the rule and mechanism of the influence of logging quotas on the intensity and duration of forest carbon sequestration at the forest farm scale, which would help to quantify the impact of different logging quotas on multi-objective forest management decisions at forest farm scale, so as to provides a theoretical basis for improving forest quality and carbon sink function. Method: A management planning model that aims to maximize the comprehensive benefits of timber production, biomass energy production and carbon sequestration was developed using simulated annealing algorithm for Pangu Forest Farm of Tahe Forestry Bureau in Greater Xing’an Mountains, in which the carbon pools of living biomass, dead wood, annually litter, wood products, logging/processing and the substitution effects of wood production and bioenergy were considered simultaneously. Then, the effects of four different logging quotas（scenario 1: 0 m³ per period ; scenario 2:19 000 m³ per period; scenario 3: 38 000 m³ per period; scenario 4: 56 000 m³ per period) on economic benefits, wood production, biomass energy production, carbon sequestration and management activities were quantified for a horizon of 100 years (10 10-year periods). Result: The total economic benefits of Pangu Forest Farm during the planning horizon was 15 416.19×10⁴ yuan, when only the benefits of carbon sequestration were considered. With the increases of the logging quota, the total economic benefits during the planning horizon showed significant increase trends, which were approximately 19.74%、39.14% and 58.81% when compared with Scenario 1. The net carbon sequestration of each period decreased significantly with the increases of planning periods, while significant increasing trends were observed for the carbon stocks of each period. The average carbon sequestration during the entire planning horizon were about 0.16-0.24 t·hm^?2a^?1, and the carbon stocks at the ending of planning horizon on forestland were as large as 77.47-77.90 t·hm^?2, namely approximately 48.07% increases were observed when compared that with the beginning of planning horizon. During the planning horizon, the proportion of medium-size timber increased significantly with the planning period (from 5.80% to 36.18%), while significant decreased trends on the proportion of small-size timber could be observed (from 45.74% to 16.09%), but the proportion of short- and small-size timber was always relatively stable (43.98% on average). The production of biomass energy was highly related with wood production for each scenario, and the ratios between bioenergy and wood production were 0.243 7,0.249 7 and 0.247 7, respectively, where the harvesting mainly focused on the trunk- (45.70%) and roots- (36.03%) components. The assigned average harvest area for scenarios 2?4 were 890, 1 742 and 2 385 hm² per period, respectively. The harvested areas mainly focused on the mild-selective cutting (from 75.08% to 67.65%), but the proportion of moderate- (from 17.98% to 22.25%) and severe- (from 6.95% to 10.10%) selective cutting both increased significantly with the increases of planning periods. Conclusion: From the long perspective of viewpoint, improving the logging quota appropriately within the region of Greater Xing’an Mountains can not only increase the intensity of forest carbon sequestration, but also significantly extend the duration of carbon sequestration.

Objective: To investigate the effects of changes in litter inputs on soil microbial necromass carbon, and provide scientific evidence for a comprehensive understanding of the interactions between plants, soil, and microorganisms on long-term carbon sequestration in forests. Method: The study focused on a subtropical natural forest of Castanopsis carlesii, a randomized block group experimental design was employed, with three treatments including litter removal, litter addition, and control. Soil physicochemical properties, amino sugar contents, and microbial necromass carbon contents were measured. Pearson correlation analysis and partial least squares path modeling (PLS-PM) were utilized to explore the influencing factors of microbial necromass carbon contents. Result: After litter removal, the contents of total amino sugars, glucosamine, galactosamine, and mannoseamine in the soil decreased by 14.7%, 33.4%, 9.3%, and 16.1%, respectively; and the galactosamine decreased by 21.7% after litter addition. The fungal necromass carbon and total microbial necromass carbon contents in the soil decreased by 16.2% and 16.1%, respectively, while bacterial necromass carbon content showed no significant change after litter removal; the total microbial necromass carbon content decreased significantly by 9.2% after litter addition, but the contribution of microbial necromass carbon to soil organic carbon under the two treatments was not significantly different. Path analysis showed that microbial biomass carbon content, soil water content , and microbial biomass were key factors driving the accumulation of soil microbial necromass carbon content under changes in litter input. Conclusion: Altering the input of litter significantly regulates the accumulation of soil microbial necromass carbon, with a particularly pronounced impact on fungal necromass carbon and a relatively minor effect on bacterial necromass carbon contents. This highlights the significance of litter in the accumulation of microbial necromass carbon contents, and maintaining an appropriate level of surface litter facilitates the stability of soil carbon pools.

Objective: Compare the differences in soil aggregation and carbon sequestration between two poplar plantation forests to reveal the basic process of carbon sequestration in plantation forests, thereby providing a theoretical basis for sustainable forest management. Method: We collected the surface soil of high density (400 plants·hm^?2) and low density (278 plants·hm^?2) poplar plantation (16 a), and classified soil aggregates into <0.25 mm, 0.25–2 mm, and >2 mm particle levels by the optimal moisture-dry sieving method, studying the content of active, slow and passive organic carbon, and the rate of soil carbon mineralization in each particle level. Result: Compared with the low-density poplar plantation forests, the composition of soil aggregates in the high-density poplar plantation forests had a higher proportion of <0.25 mm and 0.25–2 mm particle sizes and a lower proportion of >2 mm particle sizes, respectively 1.06%, 21.92% and 77.02%. There were significant differences in the organic carbon fractions in soil aggregates at all particle levels among poplar plantations of different densities. Among them, active and slow organic carbon were higher in all particle levels of high-density plantation forest soil, while passive organic carbon was lower in <0.25 mm and 0.25–2 mm particle levels. The indoor incubation experiments revealed that soil carbon mineralization rates at all particle levels were generally lower in high-density plantation forests compared to low-density plantation forests throughout the incubation stage, suggesting that conservative soil microbial carbon metabolism strategies are the key to soil organic carbon accumulation in high-density plantation forests. Further analysis revealed that stand density had a significant effect on soil aggregate particle size distribution and active and slow organic carbon, but not on soil passive organic carbon; in which the reduction of soil density under high-density stands led to the accumulation of active and slow organic carbon content. Conclusion: In summary, reasonable regulation of stand density is an important silvicultural measure that affects soil aggregate formation and organic carbon fractions in plantation forests. Reduced soil bulk density and conserved soil carbon metabolism capacity in high-density poplar plantation forests would be favorable for soil carbon sequestration.

Objective: This study aims to accurately quantify the transpiration characteristics of typical plantations in the semi-arid area and their response to meteorological factors and soil moisture, and to explore the differences in water use strategies among tree species, so as to provide a theoretical basis for integrated forest-water management in this area. Method: From May to October in 2022, the plantations of main afforestation tree species of Larix principis-rupprechtii and Betula platyphylla were selected for this study in the small watershed of Diediegou in the semi-arid area of Liupan Mountains. A fixed sample plot was set up for each type of plantation with the size of 30 m × 30 m. A total of 12 sample trees with different diameters at breath height (DBH) in each plot were chosen for monitoring the sap flow density of trunk. Meanwhile, the meteorological parameters and soil moisture of 0–60 cm soil layers were measured continuously. The differences in transpiration response of the two plantations to the daily potential evapotranspiration (PET) and relative extractable soil water (REW) were analyzed. Result: 1) From July to October, the daily transpiration of L. principis-rupprechtii and B. platyphylla plantations was 0.63 and 0.54 mm·d^?1, respectively, with the transpiration for the former being 0.09 mm·d^?1 higher than that for the latter. The daily transpiration of both plantations firstly increased and then decreased with changing month, and reached their maximum values in July, at 1.38 and 1.45 mm·d^?1, respectively. 2) The responses of daily transpiration of both plantations to PET exhibited an exponential function relationship, that is, the daily transpiration increased gradually with rising PET and finally tended to be stable, but the response trends were different among different REW levels. The increase rate of daily transpiration of L. principis-rupprechtii plantation with rising PET was relatively low when the REW was < 0.3, and rapidly increased after the REW was > 0.3, but the difference in the rates among REW levels was small. In contrast, the daily transpiration of B. platyphylla plantation continued to increase at a relatively uniform rate with rising PET in the whole variation range of REW. 3) The responses of daily transpiration of both plantations to REW also followed an exponential function relationship. However, there was a significant difference in the response trend of daily transpiration between the two plantations, that is, the increase rate of daily transpiration of L. principis-rupprechtii plantation increased with rising REW was low when PET < 2 mm·d^?1, but it rapidly increased when PET > 2 mm·d^?1, and showed little difference among the PET levels. In contrast, the increase rate of daily transpiration of B. platyphylla plantation with rising REW was more uniform and showed a continuous increase in the whole variation range of PET. Conclusion: The response of daily transpiration of L. principis-rupprechtii plantation to PET and REW is more sensitive than that of B. platyphylla plantation to PET and REW. When PET < 2 mm·d^?1 or REW < 0.3, the daily transpiration of L. principis-rupprechtii plantation is significantly higher than that of B. platyphylla plantation. When PET > 2 mm·d^?1 or REW > 0.3, the daily transpiration of L. principis-rupprechtii plantation increases rapidly to its maximum and then remains stable with the increase of PET or REW, while the daily evapotranspiration of B. platyphylla plantation tends to its maximum in a relatively uniform manner. Therefore, in the semi-arid areas with limited water, the water consumption for the transpiration of L. principis-rupprechtii plantation is higher than that of B. platyphylla plantation, and the transpiration of B. platyphylla plantation is more obviously restricted by the soil drought stress.

Objective: This study aims to explore the water use strategies of Caragana korshinskii and Populus bolleana in pure and mixed plantations, and analyze the water use relationship of the two species in the mixed plantation, influencing factors of soil water utilization in different plantations, and the effects of different plantations of C. korshinskii and P. bolleana on soil moisture environment in the eastern sandy land of the Yellow River in Ningxia, China, so as to provide theoretical guidance for the stand structure optimization and regulation of shelter forests in arid areas. Method: In the growing season of 2018 (May–October), the pure plantations of C. korshinskii and P. bolleana and the mixed plantation of C. korshinskii + P. bolleana in the eastern sandy land of the Yellow River in Ningxia, China, were used as the study object. The stable isotope technique of hydrogen and oxygen and the IsoSource mixed model were used to analyze water source of C. korshinskii and P. bolleana in pure and mixed plantations, and the similarity proportion index (PS index) was used to calculate the water use relationship of two species in the mixed plantation. Soil water content, soil nutrients and root biomass were simultaneously monitored, and the structural equation model (SEM) was used to quantify the impact of different factors on soil water utilization of two species. The effects of the two species in different plantations on soil water environment were analyzed by calculating soil water storage, soil water deficit and soil water consumption rate. Result: 1) Throughout the growing season, the main water sources of C. korshinskii in pure and mixed forest were the same, while that of P. bolleana in pure and mixed forest were opposite. 2) The PS index of C. korshinskii and P. bolleana in the mixed forest was 62.75% throughout the growing season, and there was a weak competitive relationship on water use between the two species. The PS index and water sources of the two tree species was various in different periods of the growing season, and the drought could be dealt with by the separation of water use in time and space. 3) Soil water content had the highest total effect on soil water use utilization in the three forests. Soil water content and soil nutrients were significantly negatively correlated with soil water use utilization of C. korshinskii in pure forest (P<0.01), significantly positively correlated with soil water use efficiency of C. korshinskii in mixed forest (P<0.01), and significantly positively correlated with soil water utilization of P. bolleana in both pure forest and mixed forest (P<0.05). Root biomass was significantly positively correlated with the soil water utilization in the three forests (P<0.05). 4) The soil water storage of mixed forest was higher than that of pure forest of C. korshinskii and P. bolleana, but the soil water deficit and soil water consumption rate of mixed forest were lower than those of pure forest of C. korshinskii and P. bolleana. Conclusion: The water use strategy of C. korshinskii in pure and mixed forest is basically the same, while P. bolleana in pure and mixed forest has opposite water use strategies. In the mixed plantation, C. korshinskii and P. bolleana cope with drought through the difference of water use efficiency in time and space, and mixed plantation can reduce the risk of soil dryness compared to pure forests. The main influencing factors of soil water utilization of the two species in the pure and mixed plantations are soil water content and soil nutrients.

Objective: This study aims to establish a high-quality chromosome preparation method for Juglans mandshurica with dispersed and good morphology chromosome using the male inflorescence of J. mandshurica as materials, so as to lay the foundation for further research on the molecular cytogenetics of J. mandshurica. Method: The process of anther development was observed using carbol fuchin staining. Male inflorescences at the vigorous anther cell division stage were collected and pre-treated with 1 MPa nitrous oxide (N₂O), 0.7 mmol?L^?1 cycloheximide, and 2 mmol?L^?1 8-hydroxyquinoline for different durations, respectively. The inflorescence was peeled off to take out the anthers that were enzymatically digested to obtain suspensions. Then suspensions were spread on a slide using a needle on a heater at 55 °C. The mitotic metaphase chromosomes were used for fluorescence in situ hybridization (FISH) with 45S rDNA and 5S rDNA probes. Result: 1) When the male inflorescence became a fresh green color, reached a length of about 1.5 cm, and the tip of the anther turned red, the anther cell division was vigorous and a large number of microsporocyte mother cells and mitotic metaphase chromosomes could be observed. Therefore, the optimal sampling time was when the anthers in the upper part of the male inflorescence turned red, which can ensure that most of the anthers were in the vigorous cell division period. 2) Chromosomes treated with 2 mmol?L^?1 8-hydroxyquinoline for 4, 6, and 8 hours were condensed insufficiently, had unclear margins, and exhibited obvious trailing. Most of the centromeres could not be recognized. Chromosomes treated with 0.7 mmol?L^?1 cycloheximide for 4 hours were long and condensed insufficiently, with severe trailing. Chromosomes treated for 6 hours showed appropriate condensation and good morphology, with most of the centromeres recognizable. Chromosomes treated for 8 hours had clear margins but excessive condensation, with unclear centromeres. Chromosomes treated with 1 MPa N₂O for 2 hours had appropriate length but insufficient condensation, blurry margins. Chromosomes treated with 1 MPa N₂O for 3 and 4 hours had high condensation levels, were thick and short, with no clear morphological differences between chromosomes. In addition, some chromosomes treated with N₂O for 4 hours exhibited sticky stretching. Thus, the optimal pretreatment condition for male inflorescence of J. mandshurica was 0.7 mmol?L^?1 cycloheximide for 6 hours. 3) The chromosome number of J. mandshurica was 32, with a base number of 16 (2n = 2x = 32). The FISH signals of 45S rDNA and 5S rDNA probes appeared bright on the chromosomes of J. mandshurica. The hybridization signals of 45S rDNA were located near the centromeres of one pair of metacentric chromosomes, with similar signal intensities on both chromosomes. The hybridization signals of 5S rDNA were found near the centromeres of another pair of metacentric chromosomes, with one strong and one weak signal intensity. Conclusion: By using the male inflorescence of J. mandshurica when the tip of the anther turns red, a high-quality chromosome preparation and FISH technique system for J. mandshurica in the mitosis metaphase has been successfully established. This study provides a foundation for the molecular cytogenetics research of J. mandshurica and also serves as a reference for obtaining high-quality chromosome preparations in plants with large anthers.

Objective: SPL (SQUAMOSA promoter-binding protein-like) is a class of plant specific transcription factors. They play important roles in plant growth and innate immune responses. Studies that focused on dissecting SPL gene function in poplar by using genetic transformation are still very limited. In order to explore the biological function of PdbSPL28 and its effects on disease resistance, the gene was overexpressed in Populus davidiana× P. bolleana, and differences in disease resistance between wild type (WT) and transgenic poplar were investigated. Results of this study would provide a basis for comprehensive understanding of the molecular mechanism by which the PdbSPL28 regulates disease resistance in poplar. Method: The full-length ORF of P. davidiana× P. bolleana PdbSPL28 was obtained by using homologous cloning method, and the miR156 binding site within the ORF was modified via artificial DNA synthesis technology. The pre- and post-modified PdbSPL28 were separately used to construct overexpression vector through enzymatic cleavage and ligation reactions. A vector was constructed by using the Gateway strategy, transiently transformed with tobacco epidermal cells, and used for sub-cellular localization analysis of PdbSPL28 protein. PdbSPL28 overexpression transgenic P. davidiana× P. bolleana was obtained with the method of agrobacteria-mediated leaf disc transformation, and the differences between WT and transgenic P. davidiana× P. bolleana in their resistance, leaf structure and disease index to two Diaporthe pathogens (Diaporthe nobilis and D. cercidis) were investigated with the combination of stab-injured inoculation and paraffin section technique. The urediniospore suspension of D. nobilis was sprayed on detached leaves of WT and transgenic P. davidiana × P. bolleana, and the leaves were sampled at different time after inoculation. The variations of jasmonic acid (JA) content were measured using liquid chromatography-mass spectrometry. Result: The ORF of PdbSPL28 is 1 341 bp in length and harbors one miR156 binding site. The PdbSPL28 protein has the conserved SBP domain and is localized in nuclear. Six PdbSPL28 overexpression transgenic lines were successfully obtained using the modified ORF within which the miR156 binding site was mutated. Compared with WT, transgenic P. davidiana× P. bolleana overexpressing PdbSPL28 was more resistant to two Diaporthe pathogens. Results of JA measurement indicated that the JA contents in the leaves of PdbSPL28 overexpression lines were higher than that of WT before inoculation. However, at 96 h after inoculation, the JA contents in the leaves of PdbSPL28 overexpression lines were significantly lower than that of WT. Conclusion: Sequence modification of miR156 action site can improve the probability of obtaining PdbSPL28 gene overexpression transgenic P. davidiana× P. bolleana. Overexpression of PdbSPL28 gene can enhance the resistance of P. davidiana× P. bolleana to leaf spot disease caused by Diaporthe pathogens. JA signaling pathway may play an important role in regulating the defense responses of overexpression lines during the D. nobilis infection. Results of this study forms a basis for further revealing the molecular mechanism of resistance to Diaporthe pathogens regulated by PdbSPL28 in P. davidiana× P. bolleana.

Objective: This study aims to provide a theoretical basis for the effective elimination of asymptomatic carrier pines by investigating the pathological process and causes of over-year death. Method: The proportion of over-year death with naturally infected Pinus koraiensis in Dahuofang Experimental Forest Farm in Fushun City was calculated. The symptoms of naturally infected and artificially inoculated P. koraiensis were observed. The number threshold of Bursaphelenchus xylophilus (pine wood nematodes, PWNs) in P. koraiensis with symptoms in the infected year was determined. The growth of the PWN population at different temperatures in the laboratory was measured. The period suitable for the effective growth of PWN population after the emergence of Monochamus saltuarius was determined, that is, population growth period. The time from the establishment of parasitic relationship to the onset of symptoms, namely incubation period, was calculated. The cause of over-year death of P. koraiensis infected by PWNs was revealed. Result: As of June, the over-year death proportion of naturally infected P. koraiensis was 41.4%. The naturally infected and low amount artificially inoculated P. koraiensis did not show significant changes in external and internal symptoms in the year of infection or inoculation, but when the secretion of resin stopped in the following year, the trunk moisture was low, and the needles turned reddish brown. Half of the P. koraiensis inoculated with high saturated dose PWNs showed the symptoms in that year. The symptoms indicated that the PWNs were able to infect the P. koraiensis normally, and reproduce effectively, but their reproduction was hindered at low temperatures. PWNs were successfully able to overwinter but the population decreased sharply after overwintering. The number threshold of PWNs in whole plant, which was able to cause P. koraiensis to show the symptoms, was St₁=163 ± 22 nematodes·g^?1 and the number threshold in local part of a plant was St₂=621 ± 20 nematodes·g^?1. The 38-year-old P. koraiensis was inoculated with 50 000 PWNs per tree. During the population growth period of the year, the number of PWNs in the whole plant was only 90 ± 8 nematodes·g^?1, which was less than that of St₁, and the maximum number of PWNs in local part of a plant was 350 ± 18 nematodes·g^?1, which was also less than that of St₂. The population growth period in Fushun (141 days) was shorter than that in Dalian (154 days) and Nanjing (173 days). According to calculation, the incubation period of PWNs in Fushun City was 146 days, which was longer than the population growth period. Conclusion: The small number of PWNs carried by M. saltuarius leads to a low initial infection. Additionally, the life cycle of the PWNs is affected by the temperature, manifested as a long non-growth period and short population growth period, which ultimately leads to the fact that the number of PWNs does not reach the threshold for exhibiting the symptoms on P. koraiensis during the population growth period. The above comprehensive effects eventually lead to the extension of the incubation period of PWD, and 41.4% of the dead P. koraiensis being over-year death.

Objective: This study aims to investigate the relationship between the differences in the diversity and community structure of endophytic fungi in the needles and shoots of Larix olgensis (larch) infected by Botryosphaeria laricina, and the incidence of larch dieback, so as to provide reference for the prevention of larch dieback. Method: Based on high-throughput sequencing technology, the differences in community structure, diversity and functional nutrient types of endophytic fungi between asymptomatic and diseased larch needles and shoots were analyzed by means of OTU number, identification group, diversity index and FUNGuild prediction. Result: The sequencing results showed that there were 1091 OTUs in needle samples and 1083 OTUs in shoot samples. The diversity of endophytic fungi in asymptomatic needles was significantly higher than that in the heavily infected needles, and there was no significant difference in endophytic fungal diversity between the asymptomatic and infected shoots. The dominant fungal phylum in needles and shoots was Ascomycetes, and the dominant order and genus in asymptomatic needles were Chaetothyriales and Arthrocatena, respectively. After infection with by B. laricina, the dominant order and genus in needles were Botryosphaeriales and Neofusicoccum, respectively, while Capnodiales and Microcyclosporella were the dominant fungal order and genus in shoots, respectively. LefSe analysis indicated that there were a total of 54 significant differential groups in fungal communities in needles and shoots. PCoA analysis further confirmed that the endophytic fungal communities of asymptomatic needles were significantly different from those of infected needles (anosim R=0.695, P < 0.05). The fungal nutritional types in needles were mainly pathological and saprophytic, and the pathological fungi were dominated after infection. The nutritional types of fungi in the shoots were mainly pathological and saprophytic. Conclusion: Compared with the shoots of L .olgensis, the endophytic fungal community structure in needle changes more significantly after infection by B. laricina, and the pathogen is enriched in the needles, thereby promoting the development of larch dieback.

Objective: This study aims to develop a multiplex PCR assay for identification of larvae of three noctuid moth species feeding on bamboo shoots in Zhejiang Province. Method: Species-specific multiplex PCR primers were designed for COI gene variation regions. The parameters influencing the multiplex PCR reaction were optimized, and the multiplex PCR assay was developed for identification of noctuids. The sensitivity and specificity of the proposed multiplex PCR assay were determined using standard templates. Species identification of larvae of noctuids collected from shoot-used bamboo forests was performed by the proposed multiplex PCR assay. Result: In the study, three species-specific multiplex PCR primers were designed for variation regions of COI gene in three noctuid species, and these primers were used in conjunction with the universal primer LCO1490 to amplify fragments of the COI genes of Kumasia kumaso, Oligia vulgaris, and Apamea apameoides with the sizes of 290, 390, and 590 bp, respectively. The optimized multiplex PCR was performed in a 20 μL reaction mixture including 10 μL 2× HotStart Taq PCR premix reagent, 0.5 μL (10 μmol·L^?1) each of primers LCO1490, JYE290, HYE390 and QTYE590, 1 μL DNA template, and added ddH₂O to 20 μL. The reaction conditions for the optimized multiplex PCR were 94 ℃ for 5 min followed by 35 cycles of 94 ℃ for 30 s, 59 ℃ for 30 s, and 72 ℃ for 30 s, followed by a final extension for 10 min at 72 ℃. The minimum detection limit of proposed multiplex PCR assay was 0.01 ng·μL^?1 for A. apameoides, and less than 0.001 ng·μL^?1 for K. kumaso and O. vulgaris. The identification results of larvae of noctuids collected from shoot-used bamboo forests showed that all 38 samples were able to amplify obvious specific bands, and the success rate of the multiplex PCR assay was 100%. Moreover, the species identified according to the technique in this study were completely consistent with the species identified by the COI gene sequence. Conclusion: A multiplex PCR assay for identification of larvae of noctuid species has been developed, which can quickly and efficiently identify noctuid species in shoot-used bamboo forests in Zhejiang Province. The proposed multiplex PCR assay has the advantages of less time consumption, high sensitivity, strong specificity and high accuracy.

Objective: A microscopic image recognition model TimberIDNet75 is proposed in this paper for 75 types of South American imported broadleaf timber, which provides an accurate method of multi-species recognition for customs, import and export quarantine inspection, and personnel engaged in timber identification research. Method: The TimberIDNet75 model is a medium-shallow neural network with 34 convolutional layers containing one input layer and four hidden layers. To expand the receptive field as much as possible to extract more image features, the input layer uses a 13×13×256 convolutional kernel to extract 256 types of features for each image, which are activated and pooled as the output. In the first hidden layer, two convolutions, activation and then residual correction are used, which is called“two-convolutions-one-correction-block”(TCOCB). The first hidden layer contains 3 TCOCBs, and 256 types of features are extracted as output. Then the second hidden layer contains 4 TCOCBs, extracting 512 classes of features as output. The third hidden layer contains 6 TCOCBs extracting features from the previous layer’s output, obtaining 1 024 classes of features. The fourth hidden layer contains 3 TCOCBs, after feature extraction from the output of layer 3, the features of 2 048 species were obtained, which were input into the fully connected layer after global average pooling to map the classification of 75 species. Result: The TimberIDNet75 model has an accuracy of 99.4% with a loss value of 0.044. Comparing the TimberIDNet75 model with the existing advanced deep learning models, ResNet model has an accuracy of 98.1%, VGGNet model has an accuracy of 97.1%, GoogleNet model has an accuracy of 96.2%, AlexNet model accuracy is 94.7%, ViT model accuracy is 53.2%, and TimberIDNet75 model accuracy is improved by 1.3% compared to the ResNet model, which has the highest accuracy among them. Then the TimberIDNet75 model was used to carry out practical tests on 75 randomly obtained microanatomical samples of imported broadleaf timber, and all the samples were accurately identified, with an accuracy rate of 100%. Conclusion: The TCOCB in the TimberIDNet75 model can eliminate the overfitting problem caused by model gradient drop while saving machine resources, meanwhile, the residual method makes it possible to minimize the manual intervention during model training, and the accuracy and efficiency are greatly improved.

Objective: The airborne sound insulation performance of timber structure walls is investigated across a full frequency range. It aims to identify the bottlenecks limiting the sound insulation of conventional light wood frame walls, explore the effect of installing sound insulation layers, altering frame type, and setting up windows on wall sound insulation performance, and propose a high airborne sound insulation grade timber wall system. This research provides technical support for the efficient application of timber structure walls in prefabricated buildings. Method: Using the impedance tube method, small-scale material layer experiments were conducted to compare the sound insulation performance of industrial-grade elastic rubber sheets (rubber sheets), polyurethane rubber soundproofing and shock-absorbing sheets (polyurethane sheets), and polystyrene extruded sheets (XPS sheets) within the 60-6 300 Hz frequency range. Full-scale walls sound insulation tests were performed using in the 100-5 000 Hz frequencies range using the laboratory method. We obtained single-value sound insulation levels for 18 central frequencies in 1/3 octave bands, determining the wall’s weighted sound insulation index (R_w), spectrum adaptation terms, and sound insulation grades. These were compared with autoclaved lightweight concrete (ALC) walls and cross-laminated timber (CLT) walls widely used in prefabricated buildings. Result: The rubber sheet showed higher sound insulation across the full frequency range compared to the same thickness polyurethane and XPS sheets, with sound insulation performance improving with increased sheet thickness. A 10 mm thick rubber sheet exhibited the highest sound insulation efficiency within the test range. The sound insulation of conventional light wood frame walls increased with sound wave frequency but exhibited significant resonant sound insulation dips at 125 Hz and coincident dips at 3 150 Hz, with an R_w of 43 dB. When used as partitions or enclosures, the airborne sound insulation grades were 4 and 3, respectively. Adding a 10 mm thick rubber sheet between the wall frame and oriented strand board (OSB) slightly improved the sound insulation (R_w increased to 45 dB), but the grade remained unchanged. Conventional light wood frame walls with and without rubber sheets did not meet current national standards for sound insulation in ordinary residential walls. When using a light steel frame with double gypsum board (GB) on both sides, the R_w increased to 50 dB, raising the airborne sound insulation grades to 6 and 5 for partitions and enclosures, respectively. Adding 10 mm compressed glass wool strips between the GB and light steel frame further increased R_w to 51 dB, meeting national standards for residential wall sound insulation. Composite to 200 mm thick single-layer and composite ALC walls, the thickness and surface density of light steel frame walls decreased by 35% and 70%, respectively, while achieving higher sound insulation. In the 160-630 Hz frequency range corresponding to noise from road traffic, industrial operations, and daily life, the light steel frame walls system showed significantly improved sound insulation. Installing a window with an R_w of 33 dB in a conventional light wood frame wall did not significantly change the full-frequency sound insulation curve, with an R_w of 44 dB, raising the sound insulation grades to 5 and 4 for partitions or enclosures, respectively. Converting the GB on one side of the conventional light wood frame wall to double-layered, adding a 10 mm thick rubber sheet between the wood frame and OSB, and setting up a metal damping keel between the wood frame and GB created a composite wall with a window. This wall achieved an R_w of 48 dB, eliminating or significantly reducing the low-frequency resonance dips and high-frequency coincidence dips, raising the sound insulation grades to 6 and 5, respectively, meeting national standards for residential walls. Conclusion: Compared to light wood frame walls, CLT walls exhibit lower airborne sound insulation performance. Resonance dips, coincidence dips, and sound bridging effects are the key factors limiting the sound insulation performance of conventional light wood frame walls, preventing them from meeting national standards for residential walls. Replacing wood frames with light steel frames, installing sound insulation layers, and increasing the number of wall panels effectively improve wall airborne sound insulation performance.

Objective: This study intends to provide a basis for promoting the application of bamboo scrimber in engineering by studying the variation of tensile strength of bamboo scrimber along the grain under different densities and moisture contents. Method: By referring to《Standard Test Methods for Small Clear Specimens of Timber》(ASTM D143—14), bamboo scrimber specimens with different densities (1.1, 1.2, 1.3 g·cm^?3) and moisture contents (4%, 8%, 12%, 16%, 20%) were selected for orthogonal tensile test, analyzed the tensile failure modes of bamboo scrimber parallel to grain under different density and moisture content, the linear model and parabolic model were used to fit the variation tensile strength of bamboo scrimber parallel to grain with density, and the linear model and ASTM model were used to fit the variation of tensile strength of bamboo scrimber parallel to grain with moisture content. Finality, the coupling model of tensile strength of bamboo scrimber parallel to grain with the influenced of density and moisture content was proposed. Result: The main failure forms of bamboo scrimber parallel to grain under tension were flat failure and oblique failure. The flat failure was more prone to happen with the increasing density of scrimber bamboo. and the oblique failure was more prone to happen with the increasing moisture content of bamboo scrimber. Through experimental research and data fitting, the single parameter model and the two parameter coupling model of the tensile strength of bamboo scrimber parallel to grain were proposed respectively. The theoretical results were in good agreement with the experimental results. Conclusion: Within the density range of this study, the tensile strength of bamboo scrimber parallel to grain increased with the increase of density. The tensile strength of bamboo scrimber parallel to grain decreased with the increase of moisture content. The linear combination model and the ASTM combination model can predict the theoretical value of the tensile strength of bamboo scrimber parallel to grain under the influence of the two parameters. The linear combination model was more convenient to calculate, and it was recommended to use in practical applications.

Objective: In this study, the releasing or pyrolysis of main components in agarwood were analyzed, volatiles and semi-volatiles released by incense of agarwood from Guan-Xiang Zone, Hoi-An Zone and Sin-Chew Zone were analyzed and compared to identify the odorants and their origins, which explained for the mechanism behind odor formation of agarwood incense and provided references for production zone identification and odor qualification of agarwood. Method: Sesquiterpenoids and 2-(2-phenylethyl) chromones (PECs) were isolated and purified from agarwood resin respectively by hydro distillation or ethanol extraction and precipitation. Thermo-gravity (TG) loss patterns of sesquiterpenoids, PECs and wood were analyzed by TG. Agarwood from 3 production zones were collected and the burning smoke were collected. The volatiles released by burning agarwood were analyzed and the odorants were identified by static headspace-gas-chromatograph-mass spectrum (HS-GC-MS). The PECs in the dust from the smoke were analyzed and preliminarily identified by liquid chromatograph-mass spectrum. The products from different PECs under heating were analyzed and identified by HS-GC-MS. Result: 1) Sesquiterpenoids mostly diffused into air under 200 ℃, PECs pyrolyzed gradually between 150?350 ℃ and wood burned quickly over 250 ℃. 2) Volatiles released by burning agarwood were mainly aromatic compounds and sesquiterpenoids. Types and quantity of aromatic compounds increased, which enriched the agarwood incense with spicy, sweet, almond and floral odors. The release of 7 chemicals including 2-methoxy-4-vinylphenol 3,4-dimethoxyphenol and aceteugenol decreased along with the increase of ethanol extracts of Guan-Xiang zone agarwood. Those chemicals donated smoke, dusty and wood odors. 3) The relative contents of key odor-active compounds such as (-)-spathulenol, cis-eudesm-6-en-11-ol, guaiol were highest in Guan-Xiang Zone agarwood and lowest in Sin-Chew Zone agarwood with Hoi-An Zone agarwood between them. 4) PECs in the dust of agarwood smoke were mainly comprised with Flidersia type 2-(2-phenylethyl) (FPECs) chromones and no tetrahydro-2-(2-phenylethyl) chromones (THPECs) were detected. Agarotetrol pyrolyzed into benzylacetone and benzaldehyde, 2-(2-Phenylethyl) chromone not only pyrolyzed into 6 aromatic compounds including benzaldehyde and benzyl alcohol, but became volatile under heating. Conclusion: Sesquiterpenoids, PECs and wood in agarwood maintained different thermo-mass loss patterns. Sesquiterpenoids acted as volatiles while PECs and wood pyrolyzed into aromatic compounds. Both maintain various odor attributes which impacted on the odor of agarwood incense. Incenses of burning agarwood from 3 production zones differed in the volatile compositions. Agarwood from Sin-Chew Zone diverged with those from Guan-Xiang Zone and Hoi-An Zone. The types and quantity of aromatic compounds released by different PECs when heated differed. FTPECs partly became volatile under heating.

Objective: This study aims to obtain the optimal ligninolytic enzymes production system through the preliminary screening of fungal strains, determination of the optimal culture conditions and construction of the compound fungal culture system, which provides basic and scientific basis for pretreatment of bio-pulping. Method: The fungal fruiting bodies on the trees of the Summer Palace were collected as the source of strains. The white rot fungi strains with fast growth rate and high laccase activity were screened by growth rate and guaiacol culture medium. Then, the secretion of laccase (Lac), manganese- peroxidase (MnP) and lignin-peroxidase (LiP) were measured. The effects of different carbon sources, nitrogen sources, pH, additives, metal ions, temperature on the secretion of ligninolytic enzyme system were studied by single factor experiment. According to the enzyme production, different strains were selected to construct the 1∶1 compound fungal culture system, and the enzyme production and enzyme production efficiency were studied. Result: A strain with rapid growth and high laccase activity was obtained and identified as white rot fungus Trametes hirsute. The results of single factor test showed that glucose and yeast extract were the optimal carbon and nitrogen sources for T. hirsute ligninolytic enzymes production, respectively. The ligninolytic enzymes production efficiency of adding Cu^{2 +} alone was better than that of adding both Cu²⁺ and Mn²⁺. The ligninolytic enzymes production increased first and then decreased with the increase of metal ion concentration, and 0.25 mmol·L^?1 Cu^{2 +} was the best. At 38 ℃, pH=6.5 and 0.5 mmol·L^?1 veratrol and 0.5 mmol·L^?1 p-phenylenediamine, the lignin oxidase production of T. hirsute was promoted. Based on the optimization of culture conditions, a composite fungal culture system of T. hirsute and Gloeophyllum trabeum was constructed, and its enzyme production ability was further improved. The maximum total lignin oxidase production of the cultures reached 1 505.81 U·L^?1, which was about 63.61% higher than that of the control group. The laccase activity was 84.37% higher than that of the control group, and total ligninolytic enzymes production peak was reached one day in advance. Conclusion: High laccase activity fungus T. hirsute was obtained by preliminary screening. Its ligninolytic enzyme system was significantly increased by optimizing the enzyme production conditions. Based on the optimized medium, the T. hirsute and G. trabeum compound fungal culture system further improved the total lignin oxidase production and promoted laccase to reach the peak enzyme production one day in advance. The research provides a basis for the efficient utilization of lignocellulose with biological pretreatment.

Forest fuels are the material basis for forest fires and the main carrier for the spread of forest fires. As one of the three elements of forest combustion, the load, combustion characteristics and continuous distribution of forest fuels affect the occurrence, spread and prevention of forest fires. Once a major fire occurs, it will cause serious damage to the forest ecosystem and forest resources. Therefore, it is of great significance to carry out forest fuel management, reduce fuel accumulation, improve the combustion characteristics, change their horizontal and vertical continuity to reduce forest fire risk and intensity. This article summarizes the current research status at home and abroad from two aspects: combustible control technology (manual control, mechanical removal, planned burning, chemical weed control, microbial degradation, and the construction of biological fire prevention forest belts) and evaluation methods (forest fire behavior, forest combustibility, fire risk, and ecological effects, etc.). Summarized and collated forest fuel control technology and evaluation methods for control effectiveness, the effectiveness of different regulation measures is compared, and the advantages and disadvantages of various evaluation methods are analyzed. The future research directions and evaluation methods of fuel control technology are prospected. It was pointed out that basic research on forest fuel should be carried out, appropriate control measures should be discussed for key fire risk areas, long-term monitoring and dynamic evaluation of control effect should be carried out, and the time change of control effect and ecological environment impact should be quantified. On the basis of understanding the principle of fire resistance, it is an important direction for future forest fire prevention research and management to help achieve the goal of “carbon peaking and carbon neutrality” by combining the concept of “green fire prevention” with comprehensive technologies such as forest ecological regulation.

As an important natural resource, trees have giant environmental, social, and economic values. The growth stress of trees can be generated by the interaction between cells and cell layers during wood growth and maturation. For trees, growth stress is necessary for stems and branches to grow vertically or at a constant angle. And in response to gravity, light, snow, and slope, trees are prone to produce reaction wood with high growth stress to maintain or adjust their posture. Growth stress has a great effect on the structure, chemical components, and processing of wood. Exploring the distribution and generation mechanisms of growth stress is of great significance to directional cultivation, understanding biological structure and function, the processing and utilization of wood-based materials, and the exploration of new biomimetic materials. Many researchers have attempted various experiments and simulations to discover the origin of growth stress. Different hypothetical mechanisms have been proposed in the literature based on the results of the growth stress level, microstructure, genes, chemistry, hormones, and properties. However, due to the complexity and diversity of tree structure, there are still many divergences in the generation mechanisms of growth stress. With the development of plant science and the improvement of research technology, researchers’ understanding of the growth stress is evolving. In this paper, the biomechanical effect and the testing methods of growth stress in trees were introduced, and some mainstream theories about the origin of growth stress were summarized. The general hypothetical mechanisms of growth stress generation and some special mechanisms targeted reaction wood were discussed to identify which are inconsistent with current knowledge. In conclusion, reviewing the generation mechanisms is helpful to completely understand the growth stress in trees and it can provide the theoretical basis for further research on the mechanism, the study on the variation of wood structure and properties, and the fine utilization of wood. And the exploration of the growth stress generation mechanisms can provide a solid foundation for optimization measures to the loss caused by the growth stress and biological improvement and cultivation of planted forest.

Objective: Seeds of Deutzia are small, and their survival rate is low. Because the branches of Deutzia are hollow, branch propagation is difficult. This study aims to establish a complete tissue culture system through the induction of adventitious buds from the leaves of plants in the genus Deutzia, and lay the foundation for the genetic transformation system and molecular breeding. It also provides theoretical basis and practical guidance for the innovation of de novo domestication of wild Deutzia. Method: In this study, branches with leaves of D. parviflora and D. baroniana, two common species of Deutzia in the Qinling Mountains of Shaanxi Province, were used as explants. The explants were used for primary culture, subculture, rooting culture, and then, the leaves of the cultured plantlets were used to induce callus and adventitious buds. Result: The optimal disinfection method of explants was to disinfect the surface with 75% alcohol for 10s and 0.1% mercuric chloride for 3 min. The survival rate was 100% and the contamination rate was 0. The optimal medium for D. parviflora subculture was MS + 2 mg?L^?1 6-BA, and the proliferation coefficient was 2.8. The optimal medium for D. baroniana subculture was MS + 5 mg?L^?1 6-BA^?1, and the proliferation coefficient was 4.53. The optimal medium for rooting culture was 1/2 MS + 0.8 mg?L^?1 IBA, with the proliferation coefficient of 1.74 for D. parviflora and 7.86 for D. baroniana. The explants for callus induction were the leaves on the 2–4 nodes from top to bottom of 30 day old root seedlings. The optimal medium for D. parviflora leaves to induce callus was WPM + 1 mg?L^?1 2,4-D, with the induction rate of 63%. The optimal medium for D. baroniana leaves to induce callus was WPM + 0.1 mg?L^?1 2,4-D, and the induction rate was 70%. Conclusion: This study has successfully established a regeneration system for adventitious shoot induction and plant formation using the leaves of D. parviflora and D. baroniana as explants. The optimal medium for D. parviflora adventitious bud differentiation from leaves was MS + 2 mg?L^?1 6-BA + 0.3 mg?L^?1 IBA. The optimal medium for the adventitious bud differentiation from D. baroniana leaves was MS + 5 mg?L^?1 6-BA+ 0.05 mg?L^?1 NAA.