Objective: The site classification and site quality evaluation of Pinus tabulaeformis plantation in Pingquan, Hebei Province were carried out, and the site quality was graded in order to select suitable plantations of P. tabulaeformis for construction timber. Method: The P. tabulaeformis plantation in Pingquan was investigated using the data from 92 fixed plots and stem analysis of 42 trees, the method of dominant factor analysis was used to screen out the dominant factors. The site index table was compiled by the method of comparative advantage, and the site quality was evaluated according to the table. Combined with the site index distribution map, 9 sample plots with the same age and density but different site quality were selected to analyze the physical and mechanical properties of P. tabulaeformis wood by cutting dominant trees. Result: According to the site type distribution map of P. tabulaeformis: the middle soil layer is the most distributed, accounting for 65.5% of the total area, the thin soil layer is 27.9%, the thick soil layer is the least, accounting for 6.6%; the shaded slopes are more distributed, it accounts for 76.6%, and the sunny slopes are less distributed, accounting for 23.4%. According to the distribution map of site index: the plots with site index of 9 and 10 cover an area of 14 277.665 hm², accounting for 28.1%; the plots with site index of 6, 7, and 8 cover an area of 33 648.51 hm², accounting for the total area 66.1%; only 2 973.63 hm² has a site index of 4 and 5, accounting for only 5.8% Collusionn: The quality of the site in Pingquan is at the upper-middle level, which is suitable for construction timber, for which Huangtuliangzi Town and Liuxi Manchu Township are the best sites.

Objective: The stand characteristics of 13-year-old Cyclobalanopsis glauca natural forest which was converted from Eucalyptus grandis plantations were reported, aiming to provide scientific basis for revealing the basic conditions for the conversion of plantations into natural broad-leaved forests in central-subtropical zone, the vegetation control of plantation, the protection of natural broad-leaved forest and the development of native hardwood trees. Method: 3 sample plots in size of 20 m×20 m were set in the C. glauca natural forest which was converted from E. grandis plantations in Yong'an, Fujian Province, and each plot was divided into 4 quadrats of 10 m×10 m. The arbor layer of each quadrat was investigated and one representative quadrat in each plot was selected for shrub layer investigation. At the same time, a small quadrat of 4 m×4 m was set in the center of each plot for the investigation of the herb layer. The stand characteristics such as tree species composition, diversity of the arbor layer and shrub layer, the structure and growth of the stand were analyzed by using importance values, commonly used diversity indices and main stand description factors. Result: The mean DBH, mean height, density, and volume of the 13-year-old C. glauca natural forest were 6.2 cm, 9.5 m, 6 308 stems·hm^-2, and 94.43 m³·hm^-2, respectively. The ratio of height to diameter was between 41 and 380, and the average was 155. Both the diameter and tree height structure showed the characteristics of uneven-aged forest. 36.99% of the trees in the stand were from sprouts, among which the largest number of trees was C. glauca, accounting for 57.86% and 66.12% of the total number of trees from sprouts and the total number of C. glauca trees in the stand, respectively. E. grandis was in the form of dead standing tree or dead fallen tree, and the density of dead standing tree was 966 stems·hm^-2. There were 45 species in the arbor layer, and the Shannon-Wiener index, evenness index and dominance index were 3.74, 0.68, and 0.14 respectively. The number of arbor and shrub species in the arbor layer were 34 and 11, and the importance values were 88.65% and 11.35%, respectively. There were 30 evergreen and 15 deciduous tree species in the arbor layer, with the importance values were 67.38% and 32.62%; the number of trees, tree species, and the importance value of broad-leaved evergreen were obviously more than that of deciduous broadleaf trees. Broad-leaved evergreen was the main part of the arbor layer and C. glauca was the dominant species with its relative abundance (32.36%), relative frequency (7.69%), relative dominance (16.75%) and importance value (18.94%) being the largest in the arbor layer. There were 27 tree species in the shrub layer. The Shannon-Wiener index, evenness index and dominance index were 3.69, 0.78, and 0.13, respectively. The tree species of arbor and shrub species were 15 and 12, respectively, but the proportion (69.85%) and importance value (60.87%) of shrub species were higher than that of arbor species (the percentage and importance value were 30.15% and 39.13%, respectively). The number of trees, tree species, and the importance value of evergreen tree species were much higher than deciduous tree species. The majority of shrub layer was evergreen shrub and Camellia sinensis was the dominant species in the layer. Compared with the natural C. glauca forests of similar age, there were no differences in characteristics of the 13-year-old C. glauca natural forest, appearing to be a typical subtropical natural broad-leaved forest at young age. In both arbor and shrub layer, there were many precious or high value timber tree species. Conclusion: The E. grandis plantation has been successfully converted into a 13-year-old C. glauca natural forest that has a high crown density, high density of trees, high height-diameter ratio, rich tree species diversity and distinct characteristics of uneven-aged stands. There was no essential difference between the stand characteristics of this 13-year-old C. glauca natural forest with those natural C. glauca forests at similar age. It was a typical subtropical natural broad-leaved forest in the young period and a typical case of successful conversion of the subtropical plantation into a natural broad-leaved forest.

Objective: Process-based models often consist of photosynthesis, respiration, and carbon allocation modules. This leads to a higher dimensionality of variables than empirical models. Thus, it is prone to the problem of insufficient data for traditional biological modelling. Based on a carbon balance model CROBAS, the study applied a hybrid modelling approach to optimize the parameters of CROBAS-PA for Pinus armandii, to explore an effective way to parameterize complex process-based models under the condition of sparse data. Method: The objective function of the parametric optimization model was set as the deviation of the process model CROBAS-PA from the empirical model QUASSI 1.0 for tree height and biomass predictions. The decision variables for the optimization model were selected from the process model with ten parameters that vary with climate and species: the "fractal dimension" of foliage in crown, the extinction coefficient, the specific leaf area, the maximum rate of canopy photosynthesis per unit area, the specific senescence rate of foliage, the "surface area" density of foliage, the parameter relative to self-pruning, the form factor of sapwood in branches, the form factor of senescent sapwood in stem inside crown, and the form factor of senescent sapwood in branches. The constraints are the feasible domains of the process-based model parameters. A differential evolution algorithm was chosen for the optimization. A sensitivity analysis for parameters was implemented with Sobol's first-order indices and total-effect indices. Model performance was judged by mean error(ME), mean absolute error(MAE), and mean relative error(MRE). Result: Model simulations showed that the effective prediction period of the process-based CROBAS-PA could reach 20 years. The average absolute errors of tree height and diameter at breast height were less than 1.03 m and 1.19 cm, respectively; The average relative errors were less than 5.59% and 2.59%, respectively. The sensitivity analysis showed that the maximum rate of canopy photosynthesis per unit area, the specific leaf area, the extinction coefficient, and the "fractal dimension" of foliage in crown had apparent effects on the growth of height and DBH, while the effect of "surface area" density of foliage was negligible. Conclusion: The parameter-optimized CROBAS-PA can accurately predict or explain tree diameter and height growth, as well as the carbon allocation in each organ of Pinus armandii. This indicates that the hybrid modelling technique has a promising potential for the parameter estimation of complex process-based models.

Objective: Phyllostachys violascens 'Prevernalis' is an excellent bamboo species for scattered shoots. Mulching forest ground with organic material promotes early emergence of bamboo shoots and significantly improves economic benefits. Mulching will cause drastic changes to the underground growing conditions for the rhizome system of P. violascens 'Prevernalis' forests. Exploring the changes of sheath leaf traits, and taste quality of bamboo shoots under mulching and the relationship between the changes is of great significance to reveal the basis of formation of the taste quality of bamboo shoots. Method: Taking mulched bamboo shoots and natural bamboo shoots of P. violascens 'Prevernalis' with similar management level as the study subject, sheath leaf traits and taste quality of bamboo shoots were determined and analyzed. Result: 1) Compared with the natural shoots of P. violascens 'Prevernalis', the sheath leaves thickness, moisture content, aspect ratio and aspect ratio plasticity index, carotenoid and anthocyanin contents of the mulched bamboo shoots significantly increased by 317.65%, 29.82%, 22.90%, 26.32%, 567.59% and 193.93%, respectively, while the plasticity indices of single leaf dry weight, moisture content, length, area, and circumference and chlorophyll(a, b, a+b) contents of sheath leaves significantly decreased by 69.44%, 68.18%, 17.65%, 21.13%, 20.83%, 94.92%, 76.15% and 92.76%, respectively, indicating that the mulching does not have a significant effect on the morphology of sheath leaves, but it is important for the morphological plasticity index and pigment content influences. 2) Compared with the natural shoots, the soluble sugar content, sugar to acid ratio, and content and proportion of sweet amino acids of mulched shoots significantly increased by 43.68%, 89.55%, 128.57% and 125%, respectively, while the contents of total acid, oxalic acid, cellulose, bitter amino acids, and aromatic amino acids, and content and proportion of delicious amino acids opposite, indicating that mulching could significantly reduce the bitterness and roughness of bamboo shoots, while significantly improve the sweetness of bamboo shoots. 3) Redundancy analysis showed that chlorophyll(a, b, a+b) of the sheath leaves had significant negative effects on the taste quality of bamboo shoots, while the thickness of sheath leaves, aspect ratio, moisture content, carotenoids and anthocyanins had significant positive effects. Conclusion: P. violascens 'Prevernalis' shoots can cope with the obvious changes of temperature, humidity and light under mulching conditions through the adaptive changes of morphological plasticity index and pigment content of sheath leaves, and the taste quality of bamboo shoots under mulching is significantly improved. The pigment content of the sheath leaves is closely related to the taste quality of bamboo shoots, which may be an important organ that affects the taste quality of bamboo shoots through light signal transduction.

Objective: Pinus massoniana is a unique fast-growing tree species in China and is one of the main afforestation tree species in southern China, which has high economic and ecological value. Auxin has a significant effect on the secondary growth of plants. An in-depth study on the secondary growth of the stem of P. massoniana can provide theoretical basis for breeding new varieties of P. massoniana with fast growth and high yield. In this study, two-year-old P. massoniana seedlings were sprayed with different concentrations of IAA. The effects of exogenous IAA on the secondary growth of P. massoniana seedlings were analyzed in combination with physiological, biochemical, morphological traits and anatomical structures and transcriptome changes. This study could lay a foundation for elucidating molecular regulation mechanism of stem secondary growth of P. massoniana seedlings. Method: Two-year-old P. massoniana seedlings were sprayed with different concentrations of IAA(0, 1, 50, 100 mg·L^-1). After 160 days of treatment, growth traits, anatomic structure, physiological and biochemical properties were measured. The differentially expressed genes were identified by high-throughput transcriptome sequencing, and analyzed by GO and KEGG. Result: IAA treatment significantly promoted the ground diameter, cell growth(xylem and phloem thickness and xylem cell layers), physiological components of wood(lignin, cellulose and hemicellulose), endogenous hormone contents(auxin, gibberellin and brassinolide) of two-year-old P. massoniana(P < 0.05). Six cDNA libraries of CK and IAA were sequenced by Illumina sequencing, 778 differentially expressed genes(including 482 up-regulated genes and 296 down-regulated genes) were obtained. GO analysis showed that these differential genes were mainly involved in 22 categories of cell components, molecular functions and biological processes, and KEGG analysis showed that they were involved in 64 different pathways. Differentially expressed genes related to secondary growth of P. massoniana were screened, such as BRL1, GASA6, CAD, CESA2, etc. Conclusion: IAA treatment changes the content of endogenous hormones, promotes cell division, increases the accumulation of lignin, cellulose and hemicellulose. Thus it promotes the secondary growth of P. massoniana. Our results provide a solid basis for revealing the mechanism of hormone regulation of secondary growth of P. massoniana.

Objective: The secondary vascular system(SVS) regeneration can regenerate vascular tissue through tissue repairing such as past differentiation, re-differentiation or transdifferentiation after the loss of vascular system. In order to identify and study the important genes and regulatory elements related to the development of SVS, we analyzed the gene expression patterns at different regeneration stages of SVS regeneration of Populus tomentosa. It laid a foundation for further revealing the gene regulation mechanism of wood formation. Method: Four-year-old P. tomentosa clones were girdled and sampled during the active period of cambium. High throughput transcriptome analysis was performed on the inner bark and trunk surface samples after girdling, as well as the regenerated tissue obtained on the 7^th, 10^th, 14^th, 18^th and 21^st days after the girdling. Weighted gene co-expression network analysis(WGCNA) was used to obtain the modules closely related to different regeneration stages, and the expression network and biological function of these specifically expressed genes were analyzed. Result: The 14 202 differentially expressed genes, obtained by comparing differences between the samples of inner bark and trunk surface, 7^th day and trunk surface, and adjacent regeneration periods, were analyzed by WGCNA. The gene co-expression network was constructed and 10 modules related to the regeneration of SVS were obtained. Among them, the genes in Grey60 module, which were specifically expressed in the samples on the 7^th day of regeneration and inner bark, mainly involved in DNA replication, mitosis, cell division and microtubule movement. The module also contained a large number of genes related to epigenetics and cell cycle. Their high expression on the 7^th day of regeneration may activate the proliferation of dedifferentiated xylem cells and the change of tissue type, which enabled them to re-differentiate. In addition, the expression values of genes in the Pink module were very low in the mature vascular tissue samples on day 0, but they showed an upward trend in the process of regeneration, and reached the highest values on 21^th day. These genes were mainly involved in cell division, cell wall modification, phloem development, carbohydrate metabolism, DNA transcription regulation and other related biological pathways. In the Pink module, the expression of some phloem related marker genes, such as APL, NAC45/86, DOF, BSPA, PP2 and SUS, were reactivated. Same as CLE41/44 and CLV1 that can regulate the proliferation and differentiation of cambium cells, their expression level increased gradually from the 10^th day. At the late stage of SVS regeneration on the 18^th and 21^st day, the re-differentiated cambium had completed structural reconstruction and could undergo cell division and differentiation. The xylem marker genes and secondary wall regulatory factors were highly expressed at this stage. Conclusion: At the early stage of SVS regeneration of P. tomentosa, the dedifferentiated xylem cells regained the ability of cell division through epigenetic and cell cycle regulation; then the cell differentiation of phloem was started, and the regeneration cambium began cell proliferation and differentiation; at the late stage of regeneration, the cambium re-differentiated into xylem and phloem through the regulation of related genes. Through the analysis of gene expression and identification of regulatory modules in the process of SVS regeneration, we further verified the genetic regulatory basis of SVS regeneration, and also laid a foundation for revealing the regulatory mechanism of plant vascular tissue regeneration.

Objective: In order to provide technical support for improving the efficiency and accuracy of forest resources investigation, this paper was implemented to explore an efficient method to map the mean height of forest(MHF) with few field plot survey data, airborne light direction and ranging(LiDAR) sampling data and ZY3 stereo imaging pairs covering the full target region. Method: In Guangxi Zhuang Autonomous Region, two subfarms(Jiepai and Dongsheng) of Gaofeng forest farm were selected as our study areas. Full covered airborne LiDAR and ZY3 stereo imaging pairs combined with few field plot data were collected in 2018. DEM(digital elevation model) extracted from airborne LiDAR was treated as a historical under canopy topography, and twelve strips sampled from the airborne LiDAR data were simulated as the real airborne LiDAR sampling flight areas. DEM, twelve strips of LiDAR data and field plot data were used in the following processes. First of all, the MHF for these sampled airborne LiDAR areas were produced with field plot data, which was used as reference data(Y) for modeling. After that, an independent variable(CHM_ZY3) was obtained by subtracting the DEM from the DSM(digital surface model) extracted from ZY3 stereo imaging pairs. Finally, MHF estimation results got from ordinary least squares(OLS), k-nearest neighbor(KNN) and regression Kriging(RK) models were compared, which were used to estimate MHF combined with CHM_ZY3 data. Result: It was showed that root mean square error(RMSE) of OLS and KNN was 1.88 m and 1.96 m, the estimate accuracy(EA) was 87.18% and 86.64%, respectively. The RMSE and EA of RK_KNN was 1.86 m and 87.32%, respectively, however these parameters for RK_OLS reached to 1.84 m and 87.42%, correspondingly. Conclusion: It could be concluded that all the 2 categories and 4 types of models tested can effectively estimate MHF, and among these models, RK based models(RK_OLS and RK_KNN) are better than non-spatial models(OLS and KNN), while RK_OLS has the best performance. With known under canopy topography information, synergy utilization of the few field plot data, ZY3 stereo imaging pairs(fully covering the target area) and airborne LiDAR strips(acquired by sampling the target area) can estimate the MHF efficiently and precisely. The method proposed can provide important supports for improving the efficiency and accuracy of forest resource inventory in the future.

Objective: A comprehensive evaluation method of forest community stability based on stand internal status and neighborhood environment was established to provide enlightenment for the evaluation of stand stability. Method: Fixed sample plots were set up in Beijing, Shaanxi, Gansu and Shanxi where are the representative areas and widely distributed of Pinus tabulaeformis forest. The total station was used to locate the trees with breast height greater than 5 cm, and the composition, structure, regeneration characteristics and adjacent environment types of the stand were investigated, and the unit circle analysis method was used to analyze the characteristics of stand internal status. Based on the principle of structural unit, the concept of neighborhood environmental index(NEI) was defined. Then, a comprehensive evaluation method of stand stability based on the combination of stand internal state evaluation and NEI was established, and the stability of different types of Pinus tabulaeformis stands was evaluated by this method. Result: The results of unit circle analysis showed that the internal status of natural Pinus tabulaeformis stands in Xiaolongshan of Gansu Province was the best, followed by the natural stands of Zhongtiao Mountain, Yuncheng of Shanxi Province, Yuhuagong in Tongchuan of Shaanxi Province, Pinus tabulaeformis plantation in Dongshan, Taiyuan of Shanxi Province and Jiulongshan of Beijing, the value of forest internal state(FIS) were 0.605, 0.515, 0.479, 0.453 and 0.311, respectively. The highest NEI was Xiaolongshan natural Pinus tabulaeformis forest in Gansu Province, followed by Yuhuagong natural stand in Tongchuan, Shaanxi Province, with values of 0.75 and 0.40, respectively; the values of NEI of natural Pinus tabulaeformis forest in Zhongtiao Mountain of Shanxi Province and Jiulongshan plantation of Beijing were both 0.25, while that of Taiyuan artificial Pinus tabulaeformis stand was negative, with the value of -0.25. The comprehensive evaluation index(FCS) of stand stability of natural forest was higher than that of artificial forest. The stability of natural forest of Pinus tabulaeformis in Xiaolongshan of Gansu Province is the highest, and that of Dongshan plantation of Taiyuan was the lowest, with FCS values of 0.653 and 0.235, respectively. Conclusion: The comprehensive evaluation method based on the stand internal status and neighborhood environment could not only express the differences of the state characteristics within the stand, but also reflect the influences of the neighborhood environments on the stability, and could clearly reflect the general rule that the stability of natural forest is higher than that of artificial forest, and the evaluation results are more clear and intuitive, which provides a new idea for the stability evaluation of forest stand and has a certain guiding significance for sustainable forest management.

Object: Individual tree diameter growth model is one of forest growth and yield basic models. Stepwise regression is widely used in the selection of model variables. However, this method ignores the model uncertainty caused by the variable selection process. So the driving factors of individual tree diameter grouth of Chinese fir (Cunninghamia lanceolata) plantation were explored, the importance of different driving factors was compared, and the uncertain individual tree diameter growth model was constructed, in order to provide reference for Chinese fir managers to manage Chinese fir plantation scientifically. Method: Data for this study was sampled from Chinese fir stands in Weimin, Shaowu city, Fujian Province. Bayesian model averaging(BMA) and stepwise regression(SR) were used to analyze the effects of endogenous and climatic factors on the individual tree diameter growth of Chinese fir. Result: Competition and individual tree size were the main factors affecting annual diameter growth comparing with climate factors. Diameter growth decreased with the increase of tree number per hectare, quadratic mean diameter, sum of basal areas of trees larger than the subject tree(BAL), age and winter mean minimum temperature, whereas increased with the increase of diameter at the beginning of growth period, stand basal area, dominant height, mean coldest month temperature, mean warmest month temperature and mean annual precipitation. For most of the treatments of the four models, the posterior probability of the model obtained by SR was smaller than that of the best model obtained by BMA(which exhibited the highest posterior probability). In some cases, SR models did not belong to the top several models with higher posterior probability in the BMA model space. Conclusion: The diameter increment decreased with increasing competition and increased with increasing temperature and precipitation. BMA considered the combination of all possible variables and reflected the uncertainty of the model.

Objective: In this study, the distribution of AMF in soil in 20 typical sampling sites of Hubei and Anhui Provinces, China was investigated, in order to explore the diversity of Arbuscular Mycorrhizal Fungi (AMF) in the rhizosphere of Liquidambar formosana and understand AMF resources in L. formosana areas. Method: In this study, we selected 10, 20, 50 and 100 years old L. formosana as the research object, and collected 5-25 cm soil samples from the rhizosphere of L. formosana to determine the physical and chemical properties of the soil. The isolated AMF spores were classified and identified based on morphological characteristics. AMF infestation in 20 sampling sites was observed by KOH decolorization-trypan blue staining method. Soil nutrient analysis and redundancy analysis (RDA) were used to investigate the correlation between AMF community structure and soil factors in different sampling sites. Result: 1) It was found that 97.65% of the root samples of L. formosana out of the 20 samples were infected by AMF, and the infection rate was 49.43%-73.84%, with an average infection rate of 62.07%. The infection rate was the highest (73.84%) in Jiling mountain of Anhui Province, and the lowest (49.43%) in Hubei Jiufengshan Forest Park. There were many arbuscles and vesicles in L. formosana root with even distribution, indicating that L. formosana was easy to be infected by AMF. 2) The number of AMF spores isolated from the soil samples was 86-275 spore·(50 g)^-1 soil, and the average spore density was 166 spore·(50 g)^-1 dry soil. The highest density was in the Jiling Mountain in Anhui [275 spore·(50 g)^-1 soil] and the lowest density was in Huangshan in Anhui [86 spore·(50 g)^-1 soil]. 3) A total of 46 species and 11 genera of AMF were identified through morphological identification from Anhui and Hubei, including 12 species of genus Glomus, 13 species of genus Acaulospora and 5 species of genus Scutellospora. These were dominant genus of AM fungi in the rhizosphere soil of L. formosana. 4) The content of the total glomalin-related soil proteins (GRSP) and easily extractable glomalin-related soil proteins (GRSP) were 1.01-2.01 mg·g^-1 and 0.62-0.84 mg·g^-1, respectively. 5) There were significant differences in the diversity index of AM fungi in rhizosphere soil of L. formosana (P < 0.05), and it was found that the Pielou index (1.04 ±0.03) and Shannon index (3.55 ±0.04) were the highest in Huangshan Academy of Forestry. 6) RDA analysis revealed that soil catalase activity, soil organic matter, soil pH and soil invertase activity were significantly correlated with AMF diversity (P < 0.05). Among them, soil pH and invertase activity had the greatest impact on AMF diversity. In addition, there was a significant positive correlation between the soil sucrase and total glomalin content (r = 0.705, P < 0.05). Conclusion: This study for the first time revealed the distribution characteristics of AMF in the rhizosphere of L. formosana in Hubei and Anhui provinces. The diversity of AMF spores in rhizosphere soil is rich, and Glomus is the dominant genus. Combined with the distribution characteristics of AMF in the ecosystem, the study provides rich strain resources for the development of special AMF fertilizer for L. formosana.

Objective: Colletotrichum fructicola is the pathogen of anthracnose in Camellia oleifera. In this study, bioinformatics research methods were used to screen and analyze the effectors of Colletotrichum fructicola, and their functions were verified, so as to provide a theoretical basis for the research of disease-related genes of Colletotrichum fructicola, and to provide a reference for disease management in Camellia oleifera cultivation. Method: RNA-seq sequencing was performed at the non-infection stage (conidia) and infection stage (lesion tissue of Camellia oleifera leaves) of C. fruiticola. A series of bioinformatics software, such as BUSCA, target P, big PI predictor, and databases of GO, KEGG and PHI, were used to screen out the candidate effectors and then the effectors were quantitatively analyzed with qRT-PCR. The full-length gene of the candidate effector was cloned, and the corresponding gene function was verified by tobacco transient expression system and DAB staining. Result: The transcriptome data showed that there were 7 850 differentially expressed genes at the infection stage compared to the conidia stage. Predictive analysis of the encoded proteins of differentially expressed genes revealed that 345 proteins were classical secretory proteins, accounting for 4.39% of the total. The amino acid length of the classical secretory protein was evenly distributed in each segment, and the protein that meets the effector screening conditions (< 300 aa) accounted for about 36% of the total protein, which was relatively small. The length of the signal peptide was concentrated in 18-20 aa (48.7%), and the signal peptide cleavage site was SPase I type(88.41%). A total of 164 pieces of pathway information were gained by KEGG functional enrichment analysis, most of which were fungal metabolic pathways, secondary metabolites, and pathways related to starch and sucrose metabolism. The homology comparison result of PHI pathogen database showed that there were 80 genes related to fungal pathogenicity in the classical secretory protein, including a known effector. With the length of amino acid < 300 and cysteine residue number ≥ 4 as screening conditions, 17 candidate effector were screened out in C. fructicola after filtering the proteins with annotated functions. Nine candidate effectors were randomly selected for qRT-PCR analysis, and the results showed that the expression of all nine genes were up-regulated, which was in accordance with the results of transcriptome data. Four candidate effectors were cloned and verified by tobacco transient expression system and DAB staining, indicating that all candidate effectors was able to lead to plant cell necrosis. Conclusion: Multiple effectors are expressed during the infection period of Camellia oleifera by C. fructicola, while most of these proteins are not expressed or slightly expressed during the conidia period. This proves that the effectors is the key factor in the interaction between plant and pathogen.

Objective: In this paper, we studied the photosynthetic response characteristics of Populus alba var. pyramidalis infected with Valsa canker disease and blister canker disease, explored the response differences under the stress of two pathogens, to reveal the pathophysiological mechanism, so as to provide theoretical and experimental basis for the control of poplar canker diseases. Method: In this study, one-year-old P. alba var. pyramidalis saplings were inoculated by V. sordida and Botryosphaeria dothidea pathogens by using a epidermal girdling method, to investigate the physiological responses of the gas-exchange and chlorophyll fluorescence characteristics. The differences of photosynthetic response characteristics and water use efficiency (WUE) were compared between the V. sordida- and B. dothidea-inoculated saplings. Correlations analysis was used to reveal the relationships between the net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (Tr) and C_i(intercellular CO₂ concentration). Result: In 3-9 days after inoculation, V. sordida and B. dothidea significantly inhibited the net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (Tr), F_v/ F_m, Ф_PSⅡ, ETR and q_p of PSⅡ of poplar saplings. Moreover, V. sordida significantly declined the water use efficiency (WUE), but B. dothidea did not affected WUE. V. sordida changed the G_s-C_i relationship in pathogen infected saplings and increased the C_i at a very low level of G_s. V. sordida inhibited the photosynthesis mainly through the non-stomatal limitation pathway. However, B. dothidea did not change the G_s-C_i relationship in pathogen infected saplings, the C_i is positively correlated with G_s and B. dothidea inhibited photosynthesis through stomatal limitation pathway. Conclusion: This study has revealed that the change of F_v/F_m cannot reflect all the environmental stresses that the host plant encountered, and F_v/F_m= 0.75-0.85 is not a good criterion for the disease inspection. There are significantly differences in the photosynthetic, gas-exchange and chlorophyll fluorescence characteristic between B. dothidea and V. sordida canker diseases. Pathogen V. sordida has more severe inhibition on the photosynthesis than pathogen B. dothidea. V. sordida significantly decreases the WUE, while B. dothidea did not change the WUE of poplar saplings, which may be an important physiological reason that poplar Valsa canker disease has more severe damage than Botryosphaeria canker disease does in the arid and semi-arid region of north-west China.

Objective: Agrilus planipennis is a borer of ash tree (Emerald ash borer). In this paper we studied the expression of the odorant binding protein AplaOBP2 in the antenna of Agrilus planipennis, and investigate the ligand binding characteristics and ligand activity of the AplaOBP2. The purpose of this study is to use AplaOBP2 as target to discover new semiochemicals for A. planipennis. Method: The recombinant AplaOBP2 of A. planipennis was expressed in the prokaryotic expression system. The localization of expression of AplaOBP2 in the antenna of A. planipennis was studied using immunocytochemistry assay. The binding characteristics of the recombinant AplaOBP2 protein with 58 candidate ligands were analyzed by fluorescence competitive binding assay.The electrophysiological and behavioral responses of A. planipennis to AplaOBP2 ligands were studied by electroantennography(EAG) and a Y-tube olfactometer. Result: The recombinant AplaOBP2 protein was successfully expressed in the prokaryotic expression system.The result of immunofluorescence localization showed that AplaOBP2 protein was expressed in the lymph of olfactory sensilla S. basiconica I.The results of fluorescence competitive binding assay showed that in vitro, the recombinant AplaOBP2 exhibited high binding affinities with 6 kinds of ligands, including trans-2-hexenal, trans-2-heptenal, benzaldehyde, 4'-ethylacetophenone, 3', 4'-dimethoxyacetophenone, β-ionone, and their dissociation constants K_D were 4.44, 4.17, 5.20, 2.91, 3.45 and 0.63 μmol·L^-1, respectively. All AplaOBP2 ligands could trigger antennal responses of both males and females at the dosage of 10 mg·mL^-1. The behavioral test showed that 10 mg·mL^-1 trans-2-hexenal had significant attraction to female adults, and 10 mg·mL^-1 β-ionone had a significant evading effect on the female adults. Conclusion: AplaOBP2 is expressed in olfactory sensilla and can selectively bind affinities with aldehydes and ketones, suggesting that AplaOBP2 might play a role in olfactory perception. This study supports the role of OBPs as targets to discover new semiochemicals that could act as either attractants or repellents for A. planipennis.

Objective: Leptocybe invasa (Hymenopetra: Eulophidae) is a global invasive pest that causes serious damage to eucalyptus trees by forming galls on the twigs and leaves. The purpose of this paper is to provide a theoretical basis for the genetic study and control it by the development of EST-SSR primers and cryptic species identification. Method: The Illumina HiSeq^TM 2000 sequencing platform was used to perform transcriptome sequencing of female adults of L. invasa from 3 geographical populations. The search, tapping and primer design of EST-SSR markers were carried out by using MISA and Primer Premier 3 software, and 400 EST-SSR primer pairs were selected. Combined with 14 pairs of polymorphic G-SSR primers reported abroad, The amplification efficiency was detected by 1% agarose gel electrophoresis, and the polymorphism of the primers was verified by 8% denatured polyacrylamide gel electrophoresis. The cryptic species identification of 320 female adults from 14 geographic populations in China was conducted based on the COI gene sequence data. Result: 1) A total of 277 048 525 clean reads, including 82.86 G nucleotides, were obtained. After assembly, 44 878 unigenes were obtained, with an average length of 1 082.76 bp and an N50 of 1 976 bp. A total of 14 190 EST-SSR loci were searched using MISA software, of which the major repeat type was mononucleotide repeats(69.63% of the total EST-SSRs), followed by dinucleotide and trinucleotide repeats(16.17%, 13.51% of the total EST-SSRs, respectively). 2) A total of 205 primer pairs out of 400 EST-SSR primers were used to effectively amplify the target fragment, and the amplification efficiency was 51.25%, whereas abroad 14 primer pairs of G-SSR were all able to amplify the target fragment. 3) Polymorphism of SSR primers was verified by 8% denatured polyacrylamide gel electrophoresis, and 10 pairs of EST-SSR primers with good polymorphism were finally screened. Among the 14 pairs of G-SSR primers in foreign literature, only LiSS2, LiSS5, and LiSS13 showed polymorphism in L. invasa samples in China. 4) A total of 320 COI gene sequences of 605 bp were obtained from 14 geographic populations of L. invasa in China. The NJ phylogenetic tree constructed based on the COI gene sequence of L. invasa showed that there were only cryptic species A and cryptic species B in China, with a sample ratio of about 1:2. Conclusion: In this study, 10 pairs of EST-SSR primers suitable for the population genetics study of L. invasa in China have been developed. There are two types of cryptic species of L. invasa cryptic species A and cryptic species B, in China, of which the cryptic species A is found in China for the first time. The identification of cryptic species of L. invasa can provide a basis for the use of correct biological types in biological control of it.

Objective: An image recognition method based on convolutional neural networks(CNNs) for endangered and precious tree species was developed in this study to reach the automatic and accurate identification of timbers at the species level in multi-scene scenarios. Method: Images representing wood anatomical features were collected from transverse section of authentic wood specimens for 15 Dalbergia and 11 Pterocarpus species, and an image data set of Rosewood-26 was established. Four CNN models, i.e. AlexNet, VGG16, DenseNet-121 and ResNet-50 were constructed and pre-trained with ImageNet for transfer learning. And then the image data set of Rosewood-26 was deployed to re-train and test these models, which were comparatively analyzed and evaluated to obatin an optimal one for wood identification. A wood identification system was developed for identifying those samples collected from timber market for application test. Result: Among the four CNN models, ResNet-50 showed the highest identification accuracy(98.33%) and lower model complexity, which is preferable in the context of accurate and rapid wood identification. The ResNet-50 model achieved 100% accuracy when identifying 9 Dalbergia and 3 Pterocarpus species, and successfully discriminated P. santalinus from its look-alike species, P. tinctorius. The automated wood identification system based on ResNet-50 model exhibited an identification accuracy of 91.8% at the genus level and 77.3% at the species level. Conclusion: The wood identification system, iWood, developed in this study using CNNs is applicable in broad fields, i.e. customs enforcement, timber trade and quality inspection, and can reach automatic and accurate identification of wood species. This study will provide scientific support for promoting regulation of forest product industry chain, enhancing CITES enforcement capabilities and protecting forest species diversity.

The research on drying stresses is an important part of wood science, which is capable of guiding wood processing as well as providing an important basis for establishing and optimizing drying schedule. This study systematically and comprehensively summarized the research status of wood drying stresses from experimental research and numerical analysis, and discussed the merits and demerits for each method. It aimed to provide some valuable information for the further research on wood drying stresses, and to promote the correlational studies to a higher and deeper level as well as lay a foundation for the high quality drying of wood. In experimental research, the prong and slice method in traditional are still the commonly used method for testing wood drying stresses. The modern technologies, such as digital image correlation technology and near infrared spectroscopy, provide new opportunities to the research of wood drying stresses. However, so far there is still no a test method to wood drying stresses with high precision and good popular conditions. In terms of numerical analysis, the models of drying stresses based on wood rheological theory have become more robust, and reached a plateau. With the development of computer technology and numerical analysis software, the finite element method has been used to simulate wood drying stresses, which had some advantages in dealing with the anisotropic materials, and it is in rapidly developing stage now. Based on the current research, the experimental research and numerical analysis play irreplaceable roles in the investigation of wood drying stresses. The combination of the two is the key to comprehensively evaluating drying stresses. The exploration of new devices or technologies, which can rapidly, accurately and continuously detect wood drying stresses, is still the focus in the future research. The finite element method is the most potential numerical analysis method for wood drying stresses. The model with wide applicability should consider the multi-scale and multi-layer characteristics of wood, and also obtain accurate model parameters by the use of advanced instrument and equipment. Furthermore, the proposed model should be put into the control system of drying equipment, and providing the guidance and service to actual production.

Plant fibers as a macro material have the advantages of being a low cost abundant natural resource with a low density, high specific strength and high specific modulus, which is considered as the biodegradable renewable resource with the most promising research prospects. Plant fiber reinforced composite has a high use value and environmental protection without pollution, which not only significantly reduces the use of fossil fuels, but also reduces the greenhouse gas emissions, leading to huge market value and development prospects. Therefore, how to efficiently utilize the plant fiber resource, develop high-added value practical products and broaden the application fields have become key focuses of research and industry. Under the trend of automobile lightweight, substituting plant fiber for glass fiber and other reinforced composite materials will not only reduce the production cost and processing energy consumption, but also facilitate the construction of green, circular and low-carbon life system for auto parts products, effectively promoting the sustainable development of automobile industry. Prepreg, as an intermediate of advanced composite products, plays an important role in the development of automotive lightweight. Thus this study provides a brief overview of necessity of the continuous fiber reinforced thermoplastic polymer research; the preparation technology of continuous plant fiber as well as the continuous fiber/thermoplastic polymer prepregs commonly used in regards to the advantages, disadvantages and key technical problems. This review will expound upon the emerging technology of continuous plant fiber/thermoplastic polymer prepreg such as melt impregnation, extrusion-rolling, film stacking technique and fused deposition modeling. This paper also summarizes the application of continuous plant fiber/thermoplastic polymer composite materials used in automotive lightweight field, and analyzes the quality and production cost of automobile traditional and thin-walled door trim, as well as traditional and thin-walled bumper, in order to provide theoretical support for continuous plant fiber/thermoplastic prepreg for using in lightweight vehicles components. Finally, the research trend of continuous plant fiber/thermoplastic polymer prepreg is prospected. The future work will be focused on the preparation technology and evenly dispersed of continuous plant fiber, helping development of thinner prepreg, which thereby eliminates fiber buckling, improves the structure design, and further reduces the product cost. In order to achieve the stable production of continuous plant fiber/thermoplastic prepreg with lower porosity, improved quality and excellent performances, the existing preparation technology can be effectively combined so as to foster the strengths and circumvent the weaknesses, but also by combining the theory and practice further to develop the new manufacturing equipment and improve the production technology, so that the integrated development of material, equipment and process technology is expected to happen. At the same time, in order to promote the benign development of continuous plant fiber/thermoplastic prepreg, it is necessary to speed up the establishment of standardized evaluation system to regulate the market.

Objective: Stress wave nondestructive testing technology has been widely applied in wood and tree defect detection. The traditional stress wave imaging algorithm has low accuracy due to the limited sensor number. To improve the accuracy of the stress wave imaging algorithm and accurately reflect the position, size and decay of the internal defects of wood, the signal distribution of the stress wave on the cross section was investigated. Method: Four log samples(Pinus spp., Sapium sebiferum) and four live trees(Cinnamomum camphora, Sabina chinensis, Salix spp.) in Jiangnan University campus were selected as the samples for experiments, and the stress wave velocities were collected using FAKOPP instrument. Firstly, the stress wave velocities were corrected, and the wave ray diagram was generated, then the cross section was divided into many grid cells. Secondly, each stress wave ray was segmented, and the velocity of multiple segments on the ray was estimated, therefore the stress wave signal amount was increased and an improved stress wave ray diagram was also obtained. The velocity values of the grid cells were estimated using the improved propagation rays and the image processing method, thus the tomographic image of wood was generated. The Resistograph micro-drilling tool was used to evaluate the internal conditions of the live trees. Result: Experimental results showed that the proposed algorithm could accurately reconstruct the tomographic images of the four log samples. The Resistograph micro-drilling tool was used to perform multi-path drilling on live trees to get the resistance curves. Compared with the resistance curves, it was demonstrated that the proposed algorithm could also generated the tomographic images with a high resolution of 4 live trees. Conclusion: Based on the ray segmentation, the proposed algorithm might improve the accuracy and correlation of the initial grid cell velocity value, which could achieve high-quality imaging of wood defects, and could be effectively applied to nondestructive testing of wood.