Objective: In this study, we investigated the genetic variations of Bursaphelenchus xylophilus in Guangdong and Jiangsu Provinces, two major dispersal centers of the pest in China, in order to provide fundamental information for tracking the epidemic source of pine wilt disease and establishing effective measures to control pine wilt disease. Method: The whole genome of all B. xylophilus strains was re-sequenced by Illumina high-throughput sequencing platform with coverage>40×. The possible adapters were removed by Cutadpapt software after the sequencing result was filtered by FastQC pipeline. All sequenced data were aligned to the B. xylophilus genome by BWA software, and then Samtools and Picard were used to sort and remove redundancy from the aligned results. Freebayes was used to perform SNP calling and VCFtools was used to summarize SNP calling results derived from SNP types and genotypes. SNPRelate package was employed to construct PCA and a phylogenetic tree. Pyrosequencing method was also used to validate the accuracy of our sequencing and analysis results. Result: A total of 24 B. xylophilus strains were isolated from the infected wood in Guangdong and Jiangsu, with 12 strains from each Province. A total of 14 559 107 SNPs loci were found in all sequenced strains, including 12 990 503 SNPs loci in Guangdong and 2 109 778 SNPs loci in Jiangsu. Detailed analysis indicated that the SNP counts and homozygotes were significantly higher in Guangdong strains than those in Jiangsu strains. Moreover, the mutation genotypes with highest frequencies found in most of Guangdong strains were A→G、C→T、G→A、T→C, while those found in all of Jiangsu strains, as well as GD09 and GD12, were A→G、C→G、G→C、T→C. Cluster analysis demonstrated a notable genetic differentiation in most of the strains between Guangdong and Jiangsu. All B. xylophilus strains were clearly classified into 2 different groups in accordance with their origins, except for GD09 and GD12 which were classified into Jiangsu group. It was speculated that GD09 and GD12 isolated from Guangdong might be transmitted from Jiangsu through human activities. The subsequent pyro-sequencing results proved the validity of our sequencing and analysis results. Conclusion: There is obvious genetic differentiation of B. xylophilus strains between Jiangsu Province and Guangdong Province. Based on the occurrence timeline of B. xylophilus in China, it is speculated that most of the strains in the two Provinces might have different origins and ancestors. The B. xylophilus strains in Shaoguan and Shantou of Guangdong shared the same transmission source as those in Jiangsu province.

Objective: This study aims to explore the relationships between pathogenicity of different isolates of Bursaphelenchus xylophilus and the amplitude of defensive enzymes in the host plant, by investigating the pathogenicity of different isolates, and the activity changes of superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and polyphenol oxidation (POD) in Pinus koraiensis seedlings after inoculated with B. xylophilus. This study would provide reference for the prevention and control of the pine wood nematode disease. Method: Four-year-old P. koraiensis seedlings were inoculated separately with three different isolates (QH-1, NM-1 and CM-1) of B. xylophilus, and each plant was inoculated with 2 000 nematodes. The leaves were collected every day from next day to day 7 after inoculation, and used to analysis the activity change of SOD, CAT, PAL and POD in P. koraiensis seedlings. The pathogenicity and the external symptom were observed daily. In 35 days after the inoculation, the morbidity was recorded and nematodes were extracted from wilt seedlings, to analyze the difference in pathogenicity among QH-1, NM-1, and CM-1. Result: The activity change of SOD, CAT, PAL and POD in P. koraiensis seedlings inoculated with QH-1, NM-1, and CM-1 was obviously different, and the amplitude of enzyme activity change of the seedlings with QH-1 treatment was greater than that with NM-1 and CM-1 treatments. All three isolates of B. xylophilus were able to cause wilt to P. koraiensis seedlings, with QH-1 being more virulent than other two isolates. The strong virulent strains had greater change amplitudes of enzyme activity in inoculated seedlings. Conclusion: The virulence of B. xylophilus can be determined by measuring and analyzing the amplitude of enzyme activity change of infected P. Koraiensis seedlings The strong virulent strains cause greater changes in the amplitudes of enzyme activity in inoculated seedlings.

Objective: Injecting agents into pine trees is an effective measure to prevent pine wilt disease. Avermectin and emamectin benzoate are the two most widely used trunk injection drugs at present. However, if these two drugs are used for a long time, it is bound to lead to drug resistance of pine wood nematode. At the same time, there is also a need for more efficient, convenient and lasting new agents in production. This paper aims to explore the potency of a new compound medicament of 2% avermectin and 6%·fluopyram in prevention and treatment of pine wilt disease, in order to find an alternative trunk injection in place of avermectin and emamectin benzoate. Method: The toxicity of a new compound agent of 2% avermectin ·6% fluopyram was compared with 5% avermectin and 5% fluopyram. An indoor nematicidal experiment was conducted through the nematode immersion method to analyze the lethal effect of the three agents on pine wood nematode. The three agents were evenly sprayed with three agents in the LC₂₀ concentration on a Petri dish containing Botrytis cinerea, the feeding conditions of pine wood nematodes on B. cinerea were observed, the number of pine wood nematodes was counted, and the reproductive rate (Pf/Pi) under LC₂₀ concentration was calculated. The eggs at the bottom of the Petri dish were collected, and different concentrations of agents were added to the Petri dish. After 24 h, the eggs hatching was observed, the egg hatching rate was calculated, and the morphology of eggs was observed with Zeiss fluorescence microscope. Pine wood nematode was mixed with the agent and placed in a temperature gradient incubator, and the nematicidal activity of 2% avermectin and 6% fluopyram on pine wood nematode under different temperature conditions was analyzed. Result: The results showed that after the pine wood nematode was treated with three agents for 24 hours, the LC₅₀ values of 2% avermectin and 6%·fluopyram, avermectin 5%, and fluopyram 5% were 2.020 8, 51.153 6, and 21.607 1 mg·L^-1, respectively, and the LC₂₀ values were 0.447 9, 12.031 8, and 8.558 2 mg·L^-1, respectively. The nematicidal effect was 2% avermectin and 6% fluopyram > 5% fluopyram > 5% avermectin. The compound agent had a significant virulence synergism. After six days of spray treatment with LC₂₀ concentration of the three agents, the number of pine wood nematode in the 2%·avermectin and 6% fluopyram treatment and 5% fluopyram treatment group was only 1 425 ± 250, and 1 675 ± 377, far lower than that in 5% avermectin group (10 925 ± 504) and the control group (> 20 000). The experiment of hatching rate showed that the three agents could significantly inhibit the hatching of eggs, and the hatching rate of eggs decreased with the increase in the concentration of the agents. After 24 h, at 10 mg·L^-1, the inhibitory effect on egg hatching was 2% avermectin and 6% fluopyram > 5% avermectin > 5% fluopyram, and the hatching rate was 20.32%, 21.36%, and 22.89%, respectively. After being treated with 2% avermectin and 6% fluopyram at a concentration of 10 mg·L^-1 for 24 h vacuoles were produced in pine nematode eggs and the eggs died. In the temperature gradient experiment, within 15 ℃-35 ℃, the nematicidal activity of 2% avermectin and 6% fluopyram increased with the temperature increase in each 5 ℃. Conclusion: In summary, the new compound agent of 2% avermectin and 6% fluopyram has significant nematicidal activity against B. xylophilus and virulence synergism, and the toxicity is significantly higher than that of the two agents alone. The compound agent has the potential to become a new trunk injection for the prevention of pine wilt disease.

Objective: To reveal the mechanism of soil quality degradation and forest tree growth decline caused by mono culture of single species especially single conifer species, and consecutive cropping and to illustrate the mechanism and technical approach of the development of mixed forest with community structure in maintaining, restoring and improving the functions of forest soil. Method: Based on many years of studies on conditions and mechanisms of soil quality degradation of major forest plantations in China and practices of degradation control, and on an extensive literature study, both home and abroad, paper in-depth explore advance of the soil quality degradation and prevention and treatment caused by domestic and foreign single tree pure forest management especially management of single species coniferous pure forest, continuous cropping. A comprehensive comparison of physical and chemical properties of soil and biological activities between the single conifer species forest and different stand types of the mixed forests under similar site conditions was conducted to reveal the mechanisms of soil degradation due to mono culture of single species especially single conifer species and consecutive cropping, and to illustrate the mechanisms of and technical approaches to maintaining, restoring and improving soil functions of mixed forest. Result: Under similar site conditions, the monoculture of single species forest especially single conifer speciesforest and consecutive cropping in comparison with different stand types of the mixed forests showed decreases in the amount of litter, the quality and quantity of soil organic matter, the contents of available phosphorus, exchangeable cation, pH value, soil biochemical activities, soil fertility and tree growth, as well as the increase of severity of diseases and pests. Alternative species, proportions and models for mixed forests is clearly illustrated for the development of mixed forests with main afforestation tree species, technical approaches to improve existing single species forest especially the single conifer species plantations with poor growth into mixed forest with community structure is thoroughly elaborated. Conclusion: The development of mixed forest with community structure is the key technology to maintain, restore and improve forest soil functions, to improve forest soil productivity and to achieve sustainable management of forest plantations.

Objective: Latitudinal patterns of the sizes and allocation proportions of non-structural carbohydrates(NSC)storage in Pinus massoniana is studied to investigate the effects of growing environment,and to provide a solid basis for understanding and predicting the growth and carbon storage of trees within the context of global climate change. Method: We collected samples of needles,branches,stems,roots and soil of P. massoniana from 9 typical plantations along a latitudinal gradients in the distribution (23.0°~33.5°N) in China. The NSC concentrations and biomass in different organs of the sample tress were detected and used for biomass estimation and calculation of NSC pool. Result: The sizes of total NSC and its components(soluble sugar and starch)pools significantly linearly decreased from south to north; NSC pool and starch pool in branches,stems,and roots,and sugar pool in branches and roots showed decreasing trends along the latitudinal gradients. Starch was the main component of NSC pool,and its proportion increased linearly with the latitudes; the storage proportion of NSC,sugar,and starch varied in different organs,but was higher in stems and roots. The proportions of NSC,sugar and starch pools in branches linearly decreased with the increase of latitude,but the proportions of NSC and sugar pools in needles increased with the increase of latitude. Pool sizes of NSC,soluble sugar,and starch were positively correlated with climate variables(mean annual temperature of average,minimum,and maximum,and precipitation)and soil variables(nitrogen,and nitrogen/phosphorus ratio). Climate variables,soil factors,and their interactions explained 26.2 %,7.6 %,and 46.0 % of the variation in NSC storage,respectively. Conclusion: NSC pool of P. massoniana was mainly composed by starch,and the pools of NSC,sugar and starch allocated higher in stems and roots. The sizes of NSC,sugar and starch pools showed a linear trend with the latitudes at the whole-tree and organ levels. And climate had a stronger effect than the soil did on NSC storage.

Objective: Through quantitative analysis of Interspecific and inter-specific competition index of natural forest of Quercus aquifolioides at different altitudes in southeast Tibet, the influence of altitude on forest competition index was revealed, which provides a theoretical basis for the management and protection of Q. aquifolioides natural forest. Method: Four sample plots were set up in the Q. aquifolioides natural forest according to the altitudinal gradients in Lulang Town, Bayi District, Nyingchi City, Tibet, with dark brown mountain soil and mixed coniferous and broadleaved forest. Competitive and target trees sample plots were investigated. Hegyi single tree competition model was used to study the interspecific and inter-specific competition in the Q. aquifolioides natural forests at different altitudes; a total of five models, including the power function, logarithmic, exponential, polynomial and Logistic model were used to fit the regression relationship between DBH of target trees of Q. aquifolioides and their competition index, and the optimal function was selected. Result: 1) The competition index of Q. aquifolioides natural forest at different altitudes was different. The Interspecific competition index of 3 740 m (plot a), 3 640 m (plot b), 3 540 m (plot c)and 3 440 m (plot d) accounted for 17.11 %, 22.26 %, 30.79 %, and 70.13 % of the total competition index, respectively, indicating that plot a, b, and c were dominated by inter-specific competition, and plot d was dominated by intra-specific competition. 2) Among the associated tree species of Q. aquifolioides, the competitiveness of Abies georgei var. smithii was the strongest, followed by Betula platyphylla, and the weakest was B. utilis. 3) In all plots, the competition index of Q. aquifolioides decreased with the increase of DBH, showing a significant negative correlation. In plot a, the optimal model of the relationship between DBH and competition index of the competitive tree is the power function model, the optimal models of plot b and c are the cubic polynomial model, and the optimal model of plot d is the exponential function. Conclusion: Q. aquifolioides natural forest in southeastern Tibet is dominated by intraspecific competition at an altitude of 3 440 m, and interspecific competition at an altitude of 3 540-3 740 m. The competition index of Q. aquifolioides decreased with the increase of DBH, and tended to be stable when DBH reached 25 cm. The fitted model can be used to effectively predict the competition index of Q. aquifolioides forest.

Objective: The forest of Pinus yunnanensis undergone prescribed burning in Yuxi City, Yunnan Province was investigated by survey of sample plots, load assessment, smoke emission calculation and the spatiotemporal diffusion process simulation, in order to understand the quantitative relationship between the simulated diffusion of PM_2.5 in downwind city and the ground measurements, and to reveal the impacts of the smoke by the prescribed burning on air quality, therefore providing a theoretical basis for appropriate prescribed burning and smoke management practice. Methods: Sample plots in size of 10 m × 10 m were set up in the forest stand of P. yunnanensis undergone prescribed burning in central Yunnan. Fuel loads were estimated by drying in the laboratory, and the PM_2.5 emission of smoke was calculated by BlueSky, the spatiotemporal pattern of diffusion was analyzed quantitatively with the aid of HYSPLIT forward trajectory model, and the reliability of the results was verified by comparing with the GF-4 satellite image, finally, the relationship between the simulated and the ground measurements of PM_2.5 in Kunming City in the downwind direction of the emission was conducted. Result: The diffusion pattern of the smoke of prescribed burning simulated by HYSPLIT is consistent with the smoke area by visual detection from GF-4 satellite imagery synchronously, the PM_2.5 emission is positively correlated with fuel load and prescribed burning area, the thicker the humus, the higher the combustible load, and the more the smoke emitted. The PM_2.5 concentration of the city located in the downwind showed a significant increase trend subsequently, and the pattern of ground measurements was consistent and positively correlated (R²=0.787 43) with the simulated values of diffusion, and the air quality was degraded from 'excellence' to 'good' or even 'slightly polluted'. Conclusion: The smoke emission of prescribed burning is correlated with the fuel load, the burning area, and the thickness of humus. The smoke generated by the prescribed burning has a significant impact on urban air quality in downwind direction of the diffusion channel with a time lag. The quantitative assessment and early warning of smoke pollution before prescribed burning can effectively alleviate the damage by the smoke of prescribed burning.

Objective: The spatial structure of Cunninghamia lanceolata public welfare forest was comprehensively evaluated, and the current situation of spatial structure of different age groups was determined, in order to provide theoretical bases for formulating accurate and feasible stand spatial structure optimization and management measures. Method: Taking the Cunninghamia lanceolata public welfare forest in Lutou experimental forest farm of Pingjiang county, Hunan Province as the research object, based on the measured data of 30 sample plots, the stand spatial structure unit was determined by four adjacent trees.Taking the totalmingling degree, uniform angle index and spatial density index as the observed variables of the horizontal spatial structure of endogenous latent variables, taking the storey index, open degree and angle competition index as the observed variables of the vertical spatial structure of endogenous latent variables, and taking stand spatial structure as the exogenous latent variables, the stand spatial structure evaluation structural equation model was constructed. The path coefficient output from the structural equation model was normalized to determine the weight of each index. On these bases, the stand spatial structure was comprehensively evaluated. Result: 1) For the structural equation model of the evaluation of stand spatial structure, the normed Chi-square (χ²/df) was 1.708, which was between 1-3. The values of comparative fit index(CFI), non-normed fit index(NNFI) and incremental fit index(IFI) were 0.944, 0.924 and 0.946, respectively, which were all greater than 0.90. All the fitting indexes conformed to the appropriate reference value, and the overall fitness of the model was good. 2) The weights of horizontal spatial structure and vertical spatial structure of endogenous latent variables were 0.5229 and 0.4771 respectively, and their effects on the stand spatial structure of exogenous latent variables were roughly the same. The spatial density index of the observed variables was the key factor affecting the horizontal spatial structure. The open degree and competition index were equally weighted, and the both were key factors affecting the vertical spatial structure. 3) The comprehensive scores of young, middle and near-mature Cunninghamia lanceolata forests were 0.3781, 0.4526 and 0.3775 respectively. The stand spatial structure grades of the three age groups were in grade Ⅱ and Ⅲ. Overall, the spatial structure of Cunninghamia lanceolata public welfare forests in the study area did not reach the ideal state. The spatial structure of the forest was poor, and the mingling degree of tree species was low, being close from zero degree mixing to weak mixing state. The degree of crowding was medium, and the light transmission conditions of trees were general. The forest layer structure was single, but the competition intensity among trees was weak, and the spatial distribution pattern was good, which was in the state of uniform to approximate random distribution. Conclusion: Both the horizontal spatial structure and vertical spatial structure of the stand were the key factors affecting the stand spatial structure. The results of the structural equation model further found that the spatial density index was the most important factor affecting the stand horizontal spatial structure. The open degree and competition index were the important factors affecting the stand vertical spatial structure. Therefore, in order to improve the overall stand spatial structure in the study area, comprehensive management measures such as multispecies replanting and singleplant tending-thinning should be adopted. From the evaluation results of the stand spatial structure of the three age groups of Cunninghamia lanceolata ecological public welfare forests in the study area, it objectively reflected the current status of the stand spatial structure, indicating that the idea of using the structural equation model to evaluate the stand spatial structure was scientific and reasonable, and it was expected to provide a new idea for stand spatial structure evaluation.

Objective: This study was carried out to analyze the effects of site factors on the DBH growth of the thickest dominant tree in the stand, construct a growth model of the dominant tree in Hunan Quercus natural forests with the mixed effects of site types and derive a site quality evaluation model based on the DBH of the thickest dominant tree as an indicator. The site quality evaluation equation was expected to propose a new method for the site quality evaluation of Quercus natural forests. Method: This paper took Hunan Quercus natural forests as the research objects. Based on the measured data of 51 plots, the site factors those having significant impacts on the growth of the dominant woods at breast height were selected by the quantitative method Ⅰ, and the site factors were classified and combined according to the standard. The initial site type, through the R language, the DBH-age of the dominant tree in the natural Quercus forests in Hunan was fitted, the optimal basic model was screened, and the initial site type was added as a random effect to the basic model to construct a mixed effect model. The k-means was used to gather the class clusters the initial site types with similar effects to form a site type group, and it was added as a random effect to the optimal basic model to construct a mixed-effect model containing the site type group. By derivative, the site quality evaluation model was obtained, and the analysis of variance was used to verify the significant relationships between forest stand area and site index. Result: The site factors those having significant effects on the growth of the thickest dominant tree diameter at breast height were altitude, slope gradient, slope position, and slope aspect. The order of significance was altitude>slope gradient>slope aspect>slope position. Four theoretical growth equations were selected for fitting, and the coefficient of determination of the model was about 0.7. The optimal basic model was the Richards model, and the coefficient of determination R² was 0.731 8, the mean absolute error (MAE) was 5.442 6, the root mean square error (RMSE) was 6.879 1, and the expression equation was D=a×[1-exp(-c×AGE)]^b.By combining the selected four significant site factors to form the initial site type and adding it to the basic model to construct a mixed effect model with site types, the determination coefficient (R²) was increased to 0.9016. The k-means clustering was used to cluster the initial site types into 6 site type groups, which were added to the basic model as a random effect, the optimal model expression equation was D_j=a_j×[1-exp(-c×AGE)]^b+ε, the model's determination coefficient (R²) was increased to 0.924 4, which was 26.7% higher than that of the basic model, whereas both AIC and BIC were reduced. By plotting a polymorphic site index curve based on a mixed effect model containing site type groups, the site quality evaluation equation of Hunan Quercus natural forests, based on site classification with the dominant wood diameter at breast height as the evaluation index, was derived as SQEI_M-DBH=a_j×[1-exp(-0.03×AGE₀)]^$\left\{\frac{\ln D_j}{\ln a_j \times[1-\exp (-0.03 \times \mathrm{AGE})]}\right\}$+ε, and through the stand-off area verification, the site index SQEI_M-DBH obtained in this study was significantly related to the stand-off area. Conclusion: Site factors might have a significant impact on the growth of the diameter at breast height of the Quercus in Hunan Province. It could be theoretically feasible to evaluate the site quality of natural Quercus forests and to predict the productivity of the natural forests based on the diameter of the thickest dominant wood as an indicator, which was expected to provide a way for the evaluation of site quality of natural forests.

Objective: Forest fire is one of the important disturbance factors in forest ecosystem. Plants have ecological adaptability to different forest fire environments. Study on the adaptive changes of twig functional traits of Pinus tabuliformis under different fire severities would help to reveal the ecological trade-off strategies and adaptive mechanisms of P. tabulaeformis under different fire environments, and provide a theoretical basis for the ecological restoration of P. tabuliformis after fire. Method: P. tabuliformis in the burned area (unburned, light burned, moderate burned) of Qinyuan county, Shanxi Province was targeted. The differences and correlations among twig functional traits (twig tissue density, twig nitrogen content, twig phosphorus content, twig organic carbon content, twig nitrogen-phosphorus ratio, twig carbon-phosphorus ratio, twig carbon-nitrogen ratio) under different fire severities were studied by one-way analysis of variance and Pearson correlation analysis. The change trend of economic spectrum of P. tabuliformis twigs under different fire severities was explored by principal component analysis. Result: 1) Under three fire severities, the variation coefficient of twig carbon-phosphorus ratio was the largest, and that of twig organic carbon content was the smallest. With the increase of fire severity, twig tissue density first decreased and then increased. Twig tissue density in the control was significantly higher than that in the light burned by 11.8%, and significantly higher than that in the moderate burned by 5.6%. Twig phosphorus content increased with the increase of fire severity, which of the moderate burned was significantly higher than that of the control by 27.8%. Twig nitrogen-phosphorus ratio decreased with the increase of fire severity, which in the moderate burned was significantly lower than that of the control by 19.1%. There were no significant differences among other twig functional traits with the change of fire severity. 2) Under different fire severities, there were similar results in the correlation of twig functional traits: there was a highly significant negative correlation between twig nitrogen content and twig carbon-nitrogen ratio, and a highly significant negative correlation between twig phosphorus content, and twig nitrogen-phosphorus ratio, as well as twig carbon-phosphorus ratio, and a highly significant positive correlation between twig nitrogen-phosphorus ratio and twig carbon-phosphorus ratio. Therefore, the coupling relationship between the above traits was the most stable in the twig functional traits of P. tabuliformis. However, the increase of fire severity weakened the correlation between some traits. Compared with the control and the light burned, there were no significant correlations among twig nitrogen content, twig phosphorus content and twig carbon-phosphorus ratio, between twig phosphorus content and twig carbon-nitrogen ratio, and between twig carbon-phosphorus ratio and twig carbon-nitrogen ratio under the moderate burned. 3) There existed a twig economic spectrum of P. tabuliformis growing in the burned area. Along the fire severity of 'unburned-light burned-moderate burned', the resource trade-off strategy of twig moved to 'fast investment-benefit type', indicating that the growth rate of twigs would be accelerated. Conclusion: Fire severity has a significant effect on the functional traits of P. tabuliformis twigs, changes the allocation strategy of nutrient elements. The growth recovery of P. tabuliformis twig would be accelerated under light and moderate burned conditions. The research result can provide theoretical support for ecological restoration of burned P. tabuliformis.

Objective: Phyllostachys violascens 'Prevernalis' is an elite bamboo shoot species. Woodland mulching cultivation can obviously change the environmental conditions, such as temperature, water and light in the growth area of whip system, promote bamboo shoot germination earlier, and significantly improve the economic benefits of bamboo forest. However, the changes of carbon and nitrogen metabolism characteristics of sheath leaves under mulching and their relationship with the taste quality of bamboo shoots are not clear. This study aims to explored whether the mulching cultivation cover of P. violascens 'Prevernalis' forest can significantly affect the carbon and nitrogen metabolism of sheath leaves and whether the changes can affect the taste quality of bamboo shoots, which is of great significance for revealing the formation mechanism of bamboo shoot quality, and provides a reference for the cultivation of high-quality bamboo shoots. Method: This experiment was conducted in natural management and mulched bamboo forests with the same site conditions, and the nutrient content, carbon and nitrogen metabolic enzyme activity and taste quality index of natural and mulched bamboo shoots were measured and analyzed. Result: 1) Compared with the natural shoots, the contents of soluble sugar, starch, NSC and the activities of sucrose synthase, glutamate synthase, nitrate reductase and glutamine synthetase in sheath leaves of mulched bamboo shoots were significantly higher than those of natural shoots, however the N content was on the contrary. 2) Compared with the natural shoots, the soluble sugar content, sugar-acid ratio, sweet amino acid content and proportion of mulched shoots significantly increased, while total acid, oxalic acid, cellulose, bitter amino acids, aromatic amino acids and fresh amino acids contents decreased significantly. 3) Redundancy analysis showed that the contents of soluble sugar, starch, NSC and the activities of sucrose synthase, nitrate reductase, glutamate synthase, glutamine synthetase were significantly positively correlated with the sweet matter content of bamboo shoots, but negatively correlated with the bitter taste, sour taste and fiber content of bamboo shoots, while the N content of bamboo shoots was on the contrary. Conclusion: Mulching has an important effect on the carbon and nitrogen metabolism of P. violascens 'Prevernalis' sheath leaves, which can cope with drastic changes in the environment under mulching conditions through obvious adaptive regulation, so as to improve the taste quality of bamboo shoots.

Objective: This study aims to provide a theoretical basis for blueberry quality prediction and sensory evaluation of fresh blueberry fruit after harvest by investigating the change pattern of quality loss rate and texture parameters of blueberry fresh fruit under ice temperature condition with time and their correlation. Methods: The 'Beicun' blueberry was used as the test object, and subjected to different temperatures. The (-1±0.5) ℃ was for the ice temperature group, and (4±0.5) ℃ for the control group. The quality loss rate of fresh blueberry fruit and six texture parameters, namely hardness, brittleness, elasticity, chewiness, cohesion and adhesion, were measured at the two temperatures. The changes of quality loss rate and texture parameters with time were reflected by data fitting and linear regression. The texture parameters that were significantly related to blueberry fresh fruit quality loss rate were determined through correlation analysis. Results: Under ice temperature condition, the fitted model for the quality loss rate Y of blueberry fresh fruit versus time X₀ was Y=0.197 36 exp (X₀/5.850 47)-0.184, which showed an exponential growth, and the growth trend was significantly smaller than that of the control group. The quality parameters of blueberry fresh fruit showed to different degrees decrease with time during the experiment and but were all better than the control group. The mass loss rate Y of blueberry fresh fruit at ice temperature was significantly negatively correlated with hardness X₁, brittleness X₂ and Chewiness X₃ (P < 0.05), and the regression equation was constructed as Y=4.772-0.011 X₁-0.017 X₂-0.306 X₃. Conclusion: Ice temperature storage is more helpful to maintain the quality of fresh blueberries. The regression models constructed for the quality loss rate of fresh blueberry fruit and each texture parameter with time under the ice temperature condition are fitted with high accuracy. The chewiness, crispness and hardness of fresh blueberry fruit under ice temperature are identified as the main qualitative indicators related to the change of quality loss rate of fresh blueberry fruit, which would provide a theoretical basis for the prediction of postharvest storage time and qualitative quality change of fresh blueberry fruit.

Objective: The tissue culture technology of Litsea cubeba is not perfect and cannot satisfy the needs of industrialized breeding. In view of this, this research intends to optimize the stem callus induction and plant regeneration systems of L. cubeba, so as to improve the differentiation and rooting rates of adventitious buds, and provide technical supports for the establishment of industrial breeding and genetic transformation system of L. cubeba elite varieties. Method: In this study, the stem internodes (without bud) of L. cubeba were used as explants, and the optimum media for callus induction and plant regeneration of L. cubeba were determined through comparing the effects of different plant growth regulators on callus induction, proliferation, adventitious bud differentiation and rooting. On this basis, the transplanting tests of regenerated plants were performed to compare the effects of different substrates on the transplanting survival rates. Result: The optimum medium for callus induction of stem segments was 1/2 MS containing 0.2 mg·L^-1 6-BA, 0.3 mg·L^-1 NAA, 30 g·L^-1sucrose and 7 g·L^-1 agar, and the induction rate was 100%. The optimal medium for callus proliferation was 1/2 MS containing 0.5 mg·L^-1 6-BA, 1.0 mg·L^-1 NAA, 30 g·L^-1 sucrose and 7 g·L^-1 agar with a proliferation coefficient up to 3.43. The optimal medium for adventitious bud differentiation was 1/2 MS containing 0.5 mg·L^-1 6-BA, 0.1 mg·L^-1 IBA, 30 g·L^-1 sucrose and 7 g·L^-1 agar with a differentiation rate of 45.59% and an average number of 8.14 of adventitious buds. The optimum medium for rooting of adventitious buds was 1/2 MS containing 0.5 mg·L^-1 IBA, 20 g·L^-1 sucrose and 7 g·L^-1 agar, the rooting rate was 93.33% and the average number of roots was 6.74. After domestication, the regenerated plants were transplanted into the mixed substrate with nutrient soil and perlite (volume ratio 3 ∶1), and the survival rate reached to 83.33%. Conclusion: This research optimizes the in vitro regeneration system of L. cubeba, significantly improves the differentiation and rooting rates of adventitious buds and the transplanting survival rate of regenerated plants, which can provide a technical support for the industrialized breeding of L. cubeba elite varieties.

Objective: This study aims to explore the structure, diversity and functional characteristics of bacterial communities in the soil, bark and leaves of healthy and diseased Idesia polycarpa plants, so as to lay a foundation for pathogenic bacteria verification and biological prevention and control of I. polycarpa diseases. Method: Based on high-throughput sequencing technology, the differences of bacterial composition, diversity and function in different organs and rhizosphere soil of healthy and diseased I. polycarpa were analyzed by OTU number, identification group, diversity index and functional prediction. Result: The sequencing results showed that different organs and areas of I. polycarpa had their own unique bacterial groups. Proteobacteria, Actinobacteria and Acidobacteria were the main bacterial groups in the soil, and Cyanobacteria and Proteobacteria were the main bacterial groups in bark and leaves. The relative abundance of Brenneria and Hafnia-Obesumbacterium of Enterobacteriaceae in the bark of diseased I. polycarpa was significantly higher than that of healthy I. polycarpa. The results of diversity analysis showed that the diversity and richness of bacterial communities in all organs and areas of I. polycarpa were soil > bark > leaf from high to low. There was no significant difference in Chao1 index, Shannon index and Simpson index between healthy and diseased plants, and the Simpson index of bacteria in diseased tree bark was significantly higher than that of healthy bark. The PICRUSt function prediction showed that the genes related to biosynthesis in rhizosphere soil of diseased I. polycarpa were enriched, and the genes related to Staphylococcus aureus infection and amino acid metabolism in bark of diseased I. polycarpa were enriched. Conclusion: The bacterial community structure and diversity in different organs and areas of I. polycarpa are affected after the plants are infected. The bacterial community structure in the leaf area is less affected. There are significantly differences in the community structure and function of bacteria betwenn the rhizosphere soil and bark. The bacterial diversity in the bark area of infected plants increases significantly, and the forest pathogenic bacteria in the infected bark have high abundance, indicating that the main disease area of I. polycarpa is the plant bark area. This study provides a theoretical basis for studying the pathogenic mechanism and disease control of I. polycarpa.

Objective: The mobility and tropism of natural enemy insects or mites are important factors that affect their biological control effects on pests. Understanding the mobility and tropism of Paracarophenax alternatus, a mite, can provide important basis for scientific evaluation of its biological control potential and formulation of its field protection and utilization methods for biological control. Method: In this study, the translational ability, vertical tropism, ascending ability, phototropism, and Monochamus alternatus adults and eggs tropism of the female adult of P. alternatus were investigated through micro-photography, behavioral measurement and control experiments. Result: The female adult of P. alternatus had strong mobility. In the horizontal direction, the average crawling speed of female adult mites from 0- to 8-day-old was 2.17 cm ·min^-1. The 0-day-old female adult mites had the highest crawling speed up to 2.63 cm·min^-1, while the crawling speed of the 8-days-old female adult mites was the slowest, with only 1.32 cm·min^-1. With the increase of the day-age, the crawling speed showed a significant downward trend; In the vertical direction, the female adult mites had significant upward-crawling habit. The upward-crawling individuals within 1-3 hours were 9.7 times that of down-crawling ones. After releasing mites at the base of bamboo stalk in the wild for 1 to 3 days, the female adult mites ascending to 5, 7, 8 and 9 m and above accounted for 26.75%-41.75%, 18.15%-31.35%, 12.00%-26.95% and 7.30%-20.75% of the total mites, respectively. At the same time, the female adult of P. alternatus showed significant phototaxis and tropism to M. alternatus adult and eggs. In the range of the light intensity from 400 lx to 2 000 lx, the selection rate of the mites to light area was 8.1 times that of it to dark area. P. alternatus' selection rate to M. alternatus male, female and eggs was significantly higher than that of the blank control under the conditions of illumination, shading or M. alternatus illuminated with blank control shaded. Conclusion: The female adult of P. alternatus has strong mobility, upward-crawling habit, significant phototaxis and host tropism. These characteristics are helpful for the mite to efficiently search for the host eggs or gather on the body surface of M. alternatus adults to phoresy in the wild. Hence, it is a biological control factor with great application potential. In future biological control practices, it is recommended to encapsulate the mites in black or dark containers and then release from the base of pine trunks.

Objective: The aim of this study was to develop a new method to transmit entomopathogenic fungi by a biological vector, Pyemotes moseri, to biologically control the long-horned beetle, Anoplophora glabripennis, efficiently. Method: Pyemotes combined with entomopathogenic fungi spores was used as an approach to spread the entomopathogenic fungi spores into the larval galleries of the long-horned beetle for effective infection of the larvae. An outdoor simulated control test was carried out by using one meter damaged poplar trunks with the trunk base planted in soil and covered with mesh net. Each treatment was triple replicates and each replicate was made of ten damaged poplar trunks. Four treatment groups were set up, and the release unit in four treatments respectively included Pyemotes and Beauveria bassiana, Pyemotes and Metarhizium anisopliae, B. bassiana and M. anisopliae, Pyemotes. Blank control was sterile without mites in the release unit. The number of frass holes and emergence holes of long-horned beetle damaged poplar trunks was counted before experiments and re-counted after one month of treatments. After one month, the poplar trunks was split to check whether the larvae of A. glabripennis were infected by the entomopathogenic fungi. Field efficacy tests were conducted in Jiuquan city of Gansu province in August 2021. To fix the release unit on central poplar which was damaged by A. glabripennis in Shiquanhe Bridge forest maintenance region. After one month, the field control efficacy was investigated to confirm the effective control diameter of each release unit. Result: The results of outdoor simulated control test showed that the proportion of frass holes in Pyemotes and B. bassiana, Pyemotes and M. anisopliae respectively reduced 77.0 % and 83.1 % compared to blank control, and there was no new emergence hole. The larvae mortality of Pyemotes and B. bassiana was 77.5 %, Pyemotes and M. anisopliae was 85.0 %. The larvae were infected by entomopathogenic fungi in split trunks from treatment of Pyemotes and B. bassiana, Pyemotes and M. anisopliae, which was confirmed the infection was caused by the entomopathens used in the tests. Field efficacy tests in Jiuquan indicated that effective control diameter of each release unit was 10.0 m where frass holes reduced more tahn 50%. Conclusion: The vector, Pyemotes moseri can successfully transmit entomopathogenic fungi spores into the larval galleries of long-horned beetle and cause effective infection to larvae with a final mortality of 80%. Each release unit of P. moseri with fungi spores transmission diameter is 10.0 m. This vector transmission biocontrol for long-horned beetle is a firstly reported new method that the insecticidal entomopathogens are transmitted by the tiny vector P. moseri, and cause an effective infection to larvae with high mortality. This vector transmission biocontrol technique has a potential to be developed as an effective, easy operation and environmentally friendly new technique to control long-horned beetle.

In this paper, a new defoliator of Fraxinus spp., Tomostethus fraxini Niu & Wei, sp. nov., which seriously damages ash trees in North and East China, is described. T. fraxini differs from its congeners by the following characteristics: the postocellar area is strongly elevated with about 2 times the broad to long ratio; the third antennomere is slightly longer than the fourth and fifth antennomeres together; the body and legs are entirely black with silver body hairs; mesepisternum with a broad glabrous band in lower third; the abdominal tergites finely coriaceous; the setae on lateral of sheath black brown and extending backwards. Tomostethus Konow is also firstly reported formally in China. The differences in the mitochondrial genomes of the Shandong population and the Beijing population were compared, and the two populations were determined to be the same species. The genetic distances in cox 1 between the new species and the two previously reported Tomostethus spp. were compared. The result showed that the differences between them were very significant. In order to facilitate the identification of the pests of this genus, a key to the world known species of the genus was provided.

Objective: When Timoshenko free beam iteration method is used to dynamically test the elastic modulus and shear modulus of wood, its test accuracy is greatly affected by the different length thickness ratios of the specimen. Therefore, this paper was implemented to explore the applicability of calculating wood elastic modulus and shear modulus according to the iterative method of Timoshenko beam, and further focus on the test accuracy. Method: Through the truncated test of beech, SPF(spruce, pine and fir) and LVL(laminated venner lumber) specimens, the spectrums under different length thickness ratios were dynamically measured, and the first and second-order bending frequencies of free beam were read out from the spectrum. At the same time, the elastic modulus and shear modulus of wood and wood composites were calculated by iterative program. The effectiveness of the iterative method to calculate the shear modulus was verified by the free member torsional vibration method and the free plate torsional vibration mode method. Result: There was a lower limit value of length thickness ratio related to tree species. When the length thickness ratio of the specimen was less than the lower limit value, the elastic modulus and shear modulus could not be iterated by the iterative method. The elastic modulus determined by iterative method was higher than the elastic modulus test value of Euler beam. The iterative method also could give a too high calculated value of shear modulus. The elastic modulus calculated by iterative method might be higher than the elastic modulus test value based on Euler beam, and its degree is related to the length thickness ratio of the specimen. Only when the length thickness ratio of the specimen is greater than 24, the high value is less than 4%. The calculated value of shear modulus given by iterative method is related to the value of rectangular section factor k. When the rectangular section factor k is equal to 0.833 and 0.913, the calculated value of the shear modulus obtained by the iterative method is 12.2% and 2.3% (19.9% and 9.3%) higher than the measured value of the free member torsional vibration method (free plate torsional vibration mode method), respectively. Conclusion: In order to ensure the test accuracy, it is recommended to use beam specimens with length thickness ratio of 20-24 to dynamically test the first and second-order bending frequencies, and iteratively calculate the elastic modulus and shear modulus of wood with rectangular section factor of 0.913.

Objective: Worldwide studies on pathways of post-harvest carbon emission reduction in recent 30 years are reviewed to provide a theoretical basis for China-specific studies and the utilization of post-harvest carbon emission reduction to improve forestry's capacity to mitigate climate change. Method: We summarized major pathways of post-harvest carbon emission reduction worldwide and analyzed the life-cycle material flow and substitution categories of harvested wood products (HWP), the backbone of post-harvest carbon emission reduction, in 24 and 15 countries/regions, respectively. We also investigated the country-specific features in life-cycle material flows and summarized the displacement factors of major substitution categories in the above-mentioned countries. Furthermore, we provided a prospect of possible future research needs based on the literature review. Result: First, the studies in recent 30 years reported three major pathways of post-harvest carbon emission reduction, including HWP carbon storage, HWP substation benefit, and the optimized forest management considering both pre- and post-harvest carbon emission reduction. Among them, the HWP substitution benefit has been a frontier of the relevant research fields and provided new insights in forest management considering pre- and post-harvest carbon emission reduction. Second, the studies in developed countries have comprehensively analyzed domestic life-cycle material flows whereas the studies in developing countries were relatively weak, and very few modeling analyses based on the Tier-3 method recommended by the Intergovernmental Panel on Climate Change (IPCC) are available. We also found that the material flows driven by international trade are a common research gap in the studies in all these countries, which undermines the linkage of the countries involved in an HWP life cycle and restricts effective policy design to improve carbon emission reduction potential of global forestry. Third, the HWP substitution studies, which are mainly in European countries, reported that the five major substitution categories, namely, substitution in construction, energy, furniture, other products, and the material substitution without dividing specific end uses, have an average displacement factor of 1.32 t·t^-1 (n=50), 0.70 t·t^-1 (n=40), 1.03 t·t^-1 (n=21), 1.13 t·t^-1 (n=8), and 1.13 t·t^-1 (n=37), respectively. However, the displacement factors differ significantly among studies and countries. Conclusion: First, as the major developing country and the largest HWP producing and consuming countries in the world, China should improve existing IPCC Tier-2 method-based life-cycle material modeling and analysis to an IPCC Tier-3 method-based one to provide a high-quality example for other developing countries. Second, the analysis of international material flow is an important future research need, providing an opportunity for China, the largest HWP exporting and importing country in the world. Lastly, there is still large research potential in the field of HWP substitution benefit. Especially, the highly subjective fundamental assumptions and substitution scenarios have led to unreliable displacement factors, which has large room for improvement.