Objective: Taking Larix olgensis plantations as the research object, this study aims to explore the difference of site quality between different site types, grade division of site from classification of site types is realized, and accurately evaluate the site quality of L. olgensis plantations. Method: Based on the sample plot data by the national forest inventory and the forest management inventory in Jilin Province, a difference model for stand dominant height growth was constructed by generalized algebraic difference approach. The dominant site factors significant affecting dominant height growth of L. olgensis were screened by partial correlation analysis and formed the site types (ST). Site type groups (STG) is formed by clustering site types based on K-Means algorithm, and the ST and STG are taken as random effects to construct the dominant high growth mixed effect model respectively, adding exponential function, power function and constant plus power function to eliminate heteroscedasticity, autocorrelation of order 1, compound symmetry and autocorrelation-moving average, three structures were used to consider the autocorrelation, the optimal mixed effect model was selected and carried out the site rank according to the site type groups corresponding to the dominant height at 30 years. Result: The optimal difference model M1.1 evaluation index adjusted coefficient of determination ($ {R}_{\mathrm{a}}^{2} $) = 0.865, relative root mean square error (rRMSE) = 7.756%. The site factors that had significant effect on stand dominant height (P<0.01) and their partial correlation coefficients were elevation 0.379, soil thickness ?0.247, humus thickness 0.190, slope position 0.113, slope degree 0.067, respectively, the first three factors were identified as dominant site factors, and 45 site types were formed. 5 site type groups were obtained from 45 site type clusters, the optimal mixed effect model M1.7 considering site type groups, AIC (Akaike information criterion) is 4 402.492 and BIC (Bayesian information criterion) is 4 451.014, decreased by 7.42% and 7.04% compared with AIC and BIC of M1.1 respectively. Divided into 5 site grades by using M1.7, the dominant height at 30 years are 18.7, 17.6, 16.2, 14.4, 12.8 m in turn. Conclusion: Richards, Korf and Hossfeld are more suitable than other base models to derive difference models. Elevation, soil thickness and humus thickness are the dominant site factors affecting the growth of dominant height for L. olgensis. The corresponding table of site types and site grade is obtained.

Objective: By introducing the DBSCAN clustering algorithm and QuickHull convex hull detection algorithm, an adaptive endmember eigenvalue extraction (AEEE) algorithm is proposed to address the issue of manual selection of feature pixel candidate areas in the pixel ternary model combined with the pure pixel index-2D scatter plot (PPI-2DSP) algorithm. The AEEE algorithm is utilized to assess the photosynthetic vegetation coverage (f_PV), non-photosynthetic vegetation coverage (f_NPV), and bare soil coverage (f_BS) in Shenmu city and analyze their spatiotemporal variations. The effectiveness of the algorithm is verified, providing reference for the evaluation of the ecological environment and the study of vegetation fractional cover change patterns in the region. Method: Using Landsat series satellite remote sensing images as the data source, the remote sensing data is preprocessed first. Then, the normalized difference vegetation index (NDVI) and dry fuel index (DFI) of pixels are calculated. Feature pixel candidate areas are obtained through the following 4 steps: 1) Reducing the data volume using a random sampling module; 2) Clustering with the DBSCAN algorithm to remove outlier data and identify the largest cluster; 3) Computing the convex hull using the QuickHull algorithm to construct the boundaries of feature triangles; 4) Calculating the vertices of the largest area triangle formed by three points within the convex hull point set. Regions within a specified range centered at the three vertices are selected as feature pixel candidate areas with a vertex threshold ($\theta $). After reducing the computational complexity through the Minimum Noise Fraction transformation of preprocessed images, the pure pixel index is calculated using the PPI algorithm. Pure pixels with a pure pixel index greater than 5 are extracted using feature pixel candidate areas. The arithmetic mean values of the NDVI and DFI for these pixels are used as endmember eigenvalues into the pixel ternary model to calculate f_PV, f_NPV, and f_BS, followed by an analysis of their spatiotemporal variations. Result: The eigenvalues calculated by the AEEE algorithm for Shenmu city from 2000 to 2022 are close to those selected by the PPI-2DSP algorithm, with an average relative error of approximately 7.35%. When applied to the NDVI-DFI model, the estimation of f_PV and f_NPV for Shenmu city using AEEE exhibits errors of 4.79% and 5.05%, respectively, compared to the traditional method, meeting accuracy requirements. On a temporal scale, from 2000 to 2022, f_PV an f_NPV in Shenmu city showed an overall fluctuating growth trend, increasing at average annual rates of 0.52% and 0.22%, respectively. On a spatial scale, from 2000 to 2022, f_PV and f_NPV in Shenmu city exhibited a trend of rapid growth in the southeast and slower growth in the northwest, with f_PV primarily characterized by two main change intensities: increase (39.8%) and basically unchanged (28.0%). Conclusion: The AEEE algorithm is suitable for the adaptive extraction of endmember eigenvalues for photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), and bare soil (BS). It addresses the issue of the PPI-2DSP algorithm relying on manual selection of feature pixel candidate regions.

Objective: In this study, an ensemble learning method based on Fengyun-4B geostationary meteorological satellite remote sensing data has been proposed to estimate spatially continuous near-surface air temperature (NSAT) in the Daxing’anling Mountains forest area, which can be used to provide data support and decision-making aids for forest fire risk assessment, early warning of drought in vegetation, and evaluation of ecological environment. Method: Taking the monitoring data from 20 meteorological stations around the Daxing’anling Mountains forest area as the true value of NSAT, combined with the remote sensing data from Chinese new FY-4B geostationary satellites, and based on the thermodynamic principle of influencing the NSAT, the land surface parameters （including the land surface temperature and land surface albedo）, the topographic parameters(including the slope, aspect , and the elevation）, as well as the spatiotemporal information（including the latitude, longitude, and the time of observation) were utilized to form the feature set, respectively. After preprocessing, such as spatiotemporal matching and normalization, the estimation model of NSAT in the Daxing’anling Mountains forest area is constructed and obtained using the gradient boosting decision tree ensemble learning algorithm. The feature set was randomly divided into the training set and the testing set in the ratio of 7:3, and the accuracy of the ensemble learning model was verified using the measured NSAT data from meteorological stations. The trained model was applied to estimate the near-surface air temperature in the Daxing’anling forest area, successfully obtaining the complete spatial distribution of near-surface air temperature in the region. Result: The results showed that the estimation model constructed in this study has an overall RMSE (root mean square error) of 1.393 ℃ for the training set and 1.621 ℃ for the test set, the model has no overfitting and underfitting phenomena, and 80% of the results error is less than 2.0 ℃, so it can accurately estimate the NSATs in the Daxing’anling Mountains forest area. It can be seen that in the NSAT estimation model, the feature parameter with the most significant influence on the weights is the land surface temperature. In addition, monitoring time, land surface albedo, latitude, and elevation are all essential feature parameters based on feature weight analysis. The prediction model was also applied to mapping the NSAT in the forest area, effectively obtaining the complete spatial distribution results. Conclusion: By combining the measured NSAT at meteorological stations with FY-4B geostationary satellite remote sensing image, it can effectively obtain NSAT images with short time intervals and continuous spatial distributions, which effectively makes up for the problem of data lacking that exists when only station measurements are utilized. For areas such as deep forests, which are rare and difficult to set up stations, it not only reduces the cost and difficulty of temperature monitoring but also further improves the efficiency and fineness, which has both theoretical and applied values.

Objective: To investigate the exogenous carbon fixation and photosynthetic carbon transport and allocation in different organs of seedlings of two Chinese fir families under different CO₂ concentrations, and to provide a theoretical basis for revealing the response mechanism of carbon fixation and photosynthetic carbon allocation strategy to the increase of CO₂ concentration. Method: Three CO₂ concentration gradients were established: a control concentration of (400±50) μmol·mol^?1 (C400) and two elevated concentrations of (800±50) μmol·mol^?1 (C800) and (1 000±50) μmol·mol^?1(C1 000) were established in the seedlings of No.020 and No.061 Chinese fir, which are extensively cultivated in the southern forest region, with the objective of quantifying the flow and distribution of fixed photosynthetic carbon in diverse tissues and organs at varying stages following tracer labeling, employing the ¹³C labeling method. The ¹³C labeling method was employed to label varying concentrations of CO₂, quantify the flow and distribution of fixed photosynthetic carbon in each tissue and organ at different stages of the tracer labelling process, and analyse the net photosynthetic rate. The objective is to ascertain the proportion of biomass distributed to each organ and to elucidate the growth differences. Furthermore, the aim is to determine the differences in carbon fixation capacity and the in vivo distribution of photosynthetic carbon in seedlings of each Chinese fir family under different CO₂ concentration conditions. Result: The ¹³C allocation and biomass allocation ratios of all tissue organs in seedlings of each Chinese fir family exhibited a pattern of leaf > stem > root under different CO₂ concentration treatments. As the CO₂ labelling concentration increased, the net photosynthetic rate and δ¹³C value of each organ in seedlings of each Chinese fir family generally increased subsequently. No.020 facilitated the transfer of ¹³C to the roots, as evidenced by an increase in the latter. Following a 1 d treatment, the C800 and C1 000 treatments resulted in 50.40% and 109.63% of the ¹³C allocation to the roots, respectively, in comparison to the C400 treatment. Following 30 d, the ¹³C allocation ratio of No.020 aboveground exhibited an increase of 6.23% and 6.03% in comparison to the C400 treatment, while the ¹³C allocation ratio of stems demonstrated a rise of 39.50% and 50.31%, respectively. The C800 and C1 000 treatments yielded statistically significant results (P<0.05) with the ¹³C allocation ratio of No.061 root system increasing by 22.40% and 70.26%, respectively. Additionally, the ¹³C allocation proportion of stems decreased by 2.45% and 15.10%(P<0.05), respectively, while the biomass allocation proportion of No.061 stems decreased by 12.44%. Conversely, the biomass allocation proportion of roots increased by 5.22% under the C1 000 treatment. Conclusion: In conditions of normal atmospheric CO₂ concentration, No.020 fir seedlings demonstrate a greater capacity for metabolic translocation. The elevated CO₂ concentrations promoted higher net photosynthetic rates and increased photosynthetic carbon synthesis in the seedlings of the two Chinese fir. Furthermore, the accelerated downward transport of photosynthetic carbon in the No.020 fir seedlings was observed, as well as the impact of elevated CO₂ on the photosynthetic carbon allocation strategies in the two genotypes of the species. The fir, with No.020 tending to store photosynthetic carbon in the aboveground parts, particularly in the stems, and No.061 tending to allocate photosynthetic carbon at the expense of the stems in order to increase root photosynthetic carbon supply.

Objective: The objective of this study is to investigate the influence of nitrogen fertiliser spraying time on the nutrient utilization characteristics of Paeonia ostii 'Fengdan' (oil peony) through foliar application of nitrogen, so as to provide a reference for solving the problems of low nitrogen fertiliser utilization efficiency and high production labour cost in oil peony cultivation in China. Method: The 10-year-old P. ostii 'Fengdan' with uniform growth was used as the research object. The intelligent micro-sprinkler irrigation was applied for the leaf surface spraying every 15 days from the bud stage to the seed harvest stage. The total nitrogen application rate during the growth period was 450 kg·hm^?2, with a concentration of 5 g·L^–1 urea solution selected as the sole nitrogen source. Four nitrogen spraying times were set, 3:00–4:00 (T1), 7:00–8:00 (T2), 14:00–15:00 (T3) and 19:00–20:00 (T4), respectively. The effects of different nitrogen fertilizer spraying time during a day on dry matter accumulation, nitrogen, phosphorus and potassium absorption and utilization of P. ostii 'Fengdan' were investigated during its growth process. Result: 1) Under different nitrogen spraying time treatments, the total biomass of twigs increased gradually with the progression of growth stage, and the biomass accumulation of vegetative organs and reproductive organs was highest in the T3 treatment (P>0.05). 2) As the growth period progresses, the plant dry matter allocation proportion in vegetative organs gradually reduced, while that in reproductive organs gradually increased, reaching the highest at 120 days. Among them, the allocation in reproductive organs was highest in T3 (P>0.05), and the dry matter of reproductive organs in 2022 and 2023 accounted for 15.95%–25.81% and 15.36%–18.92% of the total dry matter at 30 days after anthesis, respectively, and reached 34.78%–45.78% at 120 days. 3) The contents of N, P and K in leaves gradually decreased with the progression of the growth period; the contents of N and P in stems first increased and then decreased, while the K content continued to decrease. N, P and K content in leaves and reproductive organs increased gradually, the accumulation of N in stems changed steadily, the accumulation of P first increased and then decreased, and the accumulation of K increased gradually. There were some differences in the nutrient accumulation in different organs between different treatments and different periods. Conclusion: With the same nitrogen concentration, the nitrogen spraying time can affect the vegetative growth and reproductive growth of P. ostii ‘Fengdan’ at different development stages. Foliar spraying of nitrogen fertilizer using micro-sprinkler irrigation from 14:00 to 15:00 is more conducive to plant twigs biomass accumulation. Plant twigs biomass accumulation, plant N, P and K accumulation, nitrogen harvest index, and nitrogen use efficiency are all the highest at that time.

Objective: To explore the alleviation effect of exogenous spraying methyl jasmonate (MeJA) on drought damage of T. ciliata seedlings and its physiological mechanism, and to determine the key regulatory factors of MeJA to improve the drought tolerance of T. ciliata. Method: In this study, 2-year-old T. ciliata seedlings were used as materials, and pot water control experiments were conducted to explore the mitigation effects of MeJA on the growth, osmotic regulation, antioxidant and photosynthetic physiological processes of T. ciliata under moderate drought stress by spraying MeJA solution on the leaves. Result: MeJA could alleviate the growth inhibition of drought on T. ciliata seedlings, restore cell morphology, and increase plant height and leaf growth rate. MeJA could promote the accumulation of soluble protein (SP) and starch (St) in T. ciliata leaves and restore cell osmotic potential. MeJA could also enhance the scavenging ability of reactive oxygen species (ROS) by enhancing the efficiency of AsA-GSH cycle in leaves, reduce the contents of malondialdehyde (MDA), superoxide anion (O₂$ \bar{\cdot} $) and hydrogen peroxide (H₂O₂), reduce oxidative damage, protect cell structure and function, and improve the drought resistance of T. ciliata seedlings. In addition, exogenous MeJA could inhibit the decomposition of chlorophyll in T. ciliata leaves under drought stress, increase stomatal conductance (g_s) and maintain its photosynthetic capacity. The VIP analysis of the PLS model further showed that SP was the key control factor affecting the drought resistance of T. ciliata, followed by O₂$ \bar{\cdot} $ , g_s and transpiration rate (T_r). Conclusion: Exogenous MeJA can effectively alleviate the damage of drought stress to T. ciliata seedlings by improving the osmotic adjustment ability and antioxidant capacity of T. ciliata leaves under drought stress, increasing stomatal conductance and improving photosynthesis. The results provide a new idea for the development of drought-resistant regulators and drought-resistant cultivation of T. ciliata.

Objective: This study aimed to elucidate the structural characteristics of the nut pericarp in different chestnut varieties and their relationship with the decay index, identifying key pericarp structural indicators that influence chestnut decay. This research provides a reference for the evaluation, selection, and scientific storage of chestnut germplasm resources resistant to decay. Method: Nuts from six chestnut cultivars planted in Qianxi County, Hebei Province (‘Libozaoli’, ‘Bayuehong’, ‘Mingjian’, ‘Taili 1’, ‘Yanshanzaofeng’, and ‘Dabanhong’) were used as experimental materials. A low-temperature storage experiment (0~2 ℃) was conducted over 180 days, with nut rot conditions surveyed every 30 days. Pericarp samples from both intact nuts before storage and rotted nuts during storage were fixed for structural observation using the paraffin section method. This facilitated analysis of pericarp structural and differences among different chestnut cultivars, changes in the structure of rotted nut pericarps, and the correlation with the decay index. Result: 1) Significant differences in the decay levels were observed among chestnut cultivars during storage. ‘Mingjian’, ‘Taili 1’, ‘Yanshanzaofeng’, and ‘Dabanhong’ showed higher storage resistance with an average rot index of 9.35%, whereas ‘Bayuehong’ and ‘Libozaoli’ were more prone to rot, with rot indexes reaching 23.53% and 21.63%, respectively. 2) Significant differences in pericarp structure were noted among the varieties. ‘Mingjian’, ‘Taili 1’, ‘Yanshanzaofeng’, and ‘Dabanhong’ had thick cuticle layers, small and regular epidermal cells, and highly dense mesocarp and endocarp layers. ‘Bayuehong’ and ‘Libozaoli’ had thin cuticle layers, larger epidermal cells, with ‘Bayuehong’ showing clear gaps in the epidermal cell layer, whereas ‘Libozaoli’, despite a tighter epidermal cell layer, had less dense mesocarp and endocarp layers. Compared to intact fruits, decayed fruits showed a significant reduction in cuticle thickness, increased gaps in the epidermal, mesocarp, and endocarp layers, and a significant decrease in pericarp density. Specifically, the cuticle layer of decayed fruits from ‘Libozaoli’ and ‘Bayuehong’ nearly vanished, with severe damage to the epidermal layer, and decomposition of the cell walls in the thin-walled cells of the mesocarp, leading to numerous cavities, whereas ‘Mingjian’, ‘Taili 1’, ‘Yanshanzaofeng’, and ‘Dabanhong’ maintained a certain thickness in the cuticle layer, and their epidermal cell structure remained relatively intact, but more cavities appeared in the middle and inner pericarp layers. 3) The analysis of the correlation between the pericarp structural indicators of intact and decayed fruits and the decay index showed that the decay index was significantly negatively correlated with the thickness of the cuticle layer, and significantly positively correlated with the gap rate of the epidermal cell layer and the gap rate of the mesocarp and endocarp layers. It was also negatively correlated with the length-to-width ratio of epidermal cells, but showed no significant correlation with other indicators. 4) Based on the four indicators of cuticle thickness, the length-width ratio of epidermal cells, and the cell gap size of the epidermal, mesocarp, and endocarp layers, the membership function method was used for comprehensive evaluation and found that the decay resistance of the six chestnut varieties was ranked from strong to weak as ‘Mingjian’ > ‘Taili 1’ > ‘Yanshanzaofeng’ > ‘Dabanhong’ > ‘Libozaoli’ > ‘Bayuehong’. The results were basically consistent with the storage test results. Conclusion: The thickness of the cuticle layer, the length-width ratio of epidermal cells, and the cell gap size of the epidermal, mesocarp, and endocarp layers are closely related to the occurrence of rot. The above four indicators can be used as an important reference for determining the decay resistance of chestnut.

Objective: This study aims to perform the genome selection (GS) for growth traits and the early selection of superior progeny in Castanopsis hystrix, which has great significance for rapid breeding of new superior varieties of C. hystrix. Method: In this study, 226 clones in the main distribution area and 479 progenies over 23 half-sib families were used as experimental materials. Genotyping datasets were obtained by high-throughput re-sequencing technology, and GS studies were conducted on the growth traits. The effects of 5 different GS models and 10 different numbers of SNPs on GS prediction accuracy were assessed using 5-fold cross-validation. Then, the genomic estimated breeding values (GEBV) of candidate populations were estimated based on the GS model, and early selection of superior progeny individuals was implemented by the Breggin multi-trait evaluation method. Result: The coefficient of variation of DBH trait in the training population was 22.73%, and greater than that of height trait (17.13%), and there was a significantly positive correlation between them (r=0.63, P<0.001). There were significant differences in both height and DBH among provenances (P<0.001). After re-sequencing and data quality control, 790 877 SNPs were obtained for each individual in the reference population and candidate population, and these SNPs were uniformly distributed in the C. hystrix genome. Based on the Genomic Best Linear Unbiased Prediction (GBLUP) model, the broad-sense heritability of height and DBH in the training population was 0.52 and 0.48, respectively, and the number of SNPs with different markers had little effect on the heritability estimation. Among the five GS models, Bayes B model had the highest GS prediction accuracy (0.21) for height, while Bayes ridge regression (BRR) model had the highest GS prediction accuracy (0.06) for DBH. The prediction accuracy of Bayes models was higher than that of GBLUP model, but the difference was not significant. For 10 different numbers of SNPs, the prediction accuracy of GS first increased during 0.5–5 K and then reached a stable stage. Bayes B model was used for height and Bayes RR model was used for DBH. The Brekin’s multi-trait evaluation method based on the GEBVs of these two traits was applied for the early selection of superior individuals in the candidate population. A total of 15 excellent progeny individuals were selected, and their mean GEBV values of height and DBH were 7.0% and 5.2% higher than those of the reference population, respectively. These superior offspring individuals were 4 438, 4 468, 4 407, 4 388, 4 052, 4 461, 4 390, 4 389, 4 410, 4 399, 4 460, 4 467, 4 212, 4 044, 4 459 and 4 020, mainly from two families of F5 and F29. Conclusion: In this study, a GS predicted model has been established, and the early selection of superior individuals has been carried out based on the GEBVs of the candidate populations, which lays the technical and material foundation for subsequent breeding of new superior varieties of C. hystrix.

Objectives: This study aims to evaluate the wind resistance of Casuarina equisetifolia and select superior individuals with rapid growth and high wind resistance in the international provenance trial forest of C. equisetifolia, which was affected by typhoon “Du Suri”. Method: In this study, a 10-year-old C. equisetifolia provenance trial forest with 109 families, 23 provenances from 10 countries, introduced from the Australian Forest Seed Center, was used as selection materials. Based on disaster survey data after undergoing typhoon "Dusu Rui" attack, the BLUP mixed linear model method was used to measure and estimate the growth traits and heritability. A comprehensive selection of superior families and individuals of C. equisetifolia was made by combining the rates of breakage, lodging, survival, and typhoon damage. Result: There were extremely significant differences (P<0.001) in tree height, diameter at breast height (DBH), volume, and survival rate among different families, and the crown width showed significant difference (P<0.01). There were no dignificant differences in lodging rate, breakage rate, and extent of damage (P>0.05). Except for the survival rate, the heritability of other traits in the Casuarina provenance forest was lower than that of individuals. By setting the selection criteria as a breeding value for volume greater than 0, excluding families with a survival rate below average, and a selection rate of 20%, 22 superior fast-growing families were identified. The genetic gains in tree height, DBH, individual tree volume, and crown width for these families were 18.27%, 23.2%, 49.9%, and 24.3%, respectively. Using positive individual tree volume breeding values and a selection rate of 10% as criteria, 106 superior individuals were selected. The genetic gains in tree height, DBH, individual volume, and crown width for these individuals were 21.0%, 44.4%, 101.8%, and 38.5%, respectively. Conclusion: There are significant differences in growth traits among different C. equisetifolia families after the typhoon attack, indicating strong potential for selection. Based on the breeding values for volume traits combined with survival rates, 22 superior families and 106 superior individuals have been selected as materials for further genetic improvement. The selection can provide materials for the establishment of the first-generation seed orchard of Casuarina and enrich the core production population.

Objective: In this study, biocontrol bacteria were isolated from kiwifruit and used for construction of biocontrol bacterial community. The pathogen of kiwifruit bacterial canker was identified in Lin'an, Zhejiang Province. This study aims to explore the biocontrol effect of the bacterial community on the pathogen of kiwifruit bacterial canker, so as to provide new insights for the prevention and control of kiwifruit bacterial canker. Method: The pathogenic bacteria causing canker disease of kiwifruit were isolated from kiwifruit planting areas in Lin'an, Zhejiang Province and identified. Based on the comparison and analysis of the metagenomes of endophytic bacteria in healthy and diseased kiwifruit branches using R language, antagonistic bacteria against the pathogenic bacteria were isolated, and a biocontrol bacterial community was constructed. The biocontrol effect of the bacterial community on the pathogenic bacteria was validated through in vitro co-cultivation and in vivo inoculation experiments. Result: 1) Kiwifruit bacterial canker in Lin'an, Zhejiang Province was caused by Pseudomonas syringae pv. actinidiae HY-05. The metagenomic sequencing results of endophytic bacteria in kiwifruit branches showed that positive interactions were more likely to form among the bacterial communities in healthy kiwifruit branches compared to diseased ones. 2) Based on R language analysis, antagonistic strains, Kineococcus mangrovi ZC-3 and Enterococcus mundtii ZC-5, against the pathogenic strain HY-05, as well as a probiotic strain, Stenotrophomonas rhizophila ZC-6, were isolated from healthy kiwifruit plants, and a biocontrol bacterial community was constructed. 3) In the in vitro co-cultivation experiment, all tested strains inhibited the growth of HY-05, with the biocontrol bacterial community constructed by ZC-3, ZC-5, and ZC-6 showing the best inhibitory effect, with a suppression rate of 100%. In the in vivo plant experiment, treatments with different biocontrol bacterial combinations were able to inhibit the occurrence of kiwifruit bacterial canker to varying degrees, with the biocontrol bacterial community constructed by ZC-3, ZC-5, and ZC-6 showing the best preventive effect, with a control efficiency of 56.00%, which was significantly different from the diseased control (P<0.01). Conclusion: Kiwifruit bacterial canker in Lin'an, Zhejiang Province is caused by P. syringae pv. actinidiae. The biocontrol bacterial community constructed from beneficial bacteria isolated from kiwifruit plants is proven to have practical biocontrol effects through in vitro and in vivo experiments. This study enriches the research system of biological control of bacterial canker in kiwifruit from a theoretical perspective, and the biocontrol bacterial community obtained can be used for precise prevention and control of kiwifruit bacterial canker, which is of practical significance for the development of the kiwifruit industry.

Objective: Under simulated forest fire preheating conditions, we studied the volatilization characteristics of volatile oils from fresh needles of Pinus yunnanensis. The aim of this study is to explore the mechanism by which volatile oils influence forest fire behaviors. Method: The volatile oil in P. yunnanensis needles was extracted by steam distillation, and the volatile oil content was determined by measuring the volume and mass. Different forest fire preheating conditions were simulated using an automatic headspace sampler, which was coupled with gas chromatography–mass spectrometry (GC–MS) to identify the composition of volatilized gases. The gas composition and content of volatile oils under the various preheating conditions were determined and compared for investigating the volatilization characteristics of the volatile oil. Result: 1) The volume content of volatile oils in fresh P. yunnanensis needles ranged from 10.61 to 15.43 mL?kg^?1, with a mean of 13.13 mL?kg^?1 and standard deviation of 2.42 mL?kg^?1. The mass content ranged between 7.86 and 9.74 g?kg^?1, with a mean of 8.52 g?kg^?1 and standard deviation of 1.05 g?kg^?1. 2) Under different preheating conditions with different temperatures and durations, a total of 48 volatile oil components were isolated and identified, most of which were terpenes, including monoterpenes, sesquiterpenes, and other oxygen-containing terpene derivatives, with trace amounts of acids, alcohols, and esters. Under the condition of preheating at 150 ℃ for 15 min, there were 27 terpenes in the volatile oil, accounting for 89.16% of the total content, including 8 monoterpenes, accounting for 54.70%, 14 sesquiterpenes, accounting for 31.86%, and 5 other oxygen-containing terpene derivatives, accounting for 2.60%. 3) The gases of volatile oils were increasingly released from P. yunnanensis needles with an increase in the preheating temperature and duration. The volatile oil slowly released at 50 ℃ and 75 ℃, with a considerably low yield of gases released. The yield of volatile oil released at 100 ℃ was notably greater than that at 50 ℃ and 75 ℃, and the volatile oil gases continued to release, without reaching an equilibrium state. The yield of volatile oil released at 125 ℃ increased substantially compared with that under the aforementioned three temperatures. After preheating for 30 min at 125 ℃, the headspace equilibrium state was reached with no further increase in the yield of volatile oil gases. When preheated at 150 ℃ for 15 min, the release of volatile oil was slowed down and gradually reached the equilibrium state. The yield of volatile oil gases released at 175 ℃ was the highest and did not reach the equilibrium state after 15 min of preheating. 4) Among the volatile oil components released by heating of P. yunnanensis needles, α-pinene was the compound with the highest content, and its relative contents ranged from 23.45% to 79.66% under the simulated preheating conditions. The highest relative content of α-pinene was obtained at the preheating temperature of 50 ℃. 5) Whereas the relative release of α-pinene under preheating at 175 ℃ for 15 min was 100%, the relative release of α-pinene under preheating at 50 ℃, 75 ℃, and 100 ℃ for 60 min was 14.2%, 25.1%, and 63.6%, respectively. The relative release of α-pinene under preheating at 125 ℃ for 30 min was as much as 90%, while the relative release of α-pinene reached 90% after only 15 min under preheating at 150 ℃. Conclusion: The higher the temperature, the easier it is for the volatile oil to rapidly release from P. yunnanensis needles. The volatile oil components in P. yunnanensis needles are released only when the preheating temperature meets a certain threshold, particularly for sesquiterpenes, but the release temperature is considerably lower than the boiling point of the component. The α-pinene, the primary volatile oil gas involved in combustion in fires, can be released at a low preheating temperature (50 ℃). Increase in the fire temperature and extension of the preheating duration can lead to a prominent increase in the release of α-pinene. Thus, the release and accumulation patterns of α-pinene in real fire environments are important topics for future research on extreme fire behaviors and high-intensity fires.

Objective: This study aims to investigate the variation of growth strain in standing Castanopsis hystrix trees and examine the influence of growth weakening treatments on this strain, with the objective of developing strategies to mitigate growth stress. Method: Trees of different ages and dominance grades (grade A: dominant and subdominant trees; grade B: intermediate trees; grade C: suppressed and dying trees; grade D: dead standing trees) were selected with the plantation in the southern subtropical region of China. The growth strain indices of standing trees, which reflect growth stress that cannot be directly measured, were determined in different seasons, and their variation patterns were analyzed. This study examined the effects of growth parameters, trunk orientations, trunk heights, and growth weakening treatments (treatment A: ringbarking at the trunk base; treatment B: injecting glyphosate at the trunk base) on growth strain. Result: Significant differences in growth strain were observed in C. hystrix standing trees with respect to dominance grades, seasons, and tree ages. The growth strain diminished as the dominance grades decreased, with the highest and lowest values occurring in summer and spring, respectively. The variation in summer was significantly greater than in other seasons. Growth strain was significantly positively correlated with average soil temperature, air temperature, and monthly precipitation during the measurement month, while it was significantly negatively correlated with soil moisture and air humidity. Growth strain increased with tree age and exhibited significant circumferential variability. Below 9.0 m of trunk height in fallen trees, the differences in growth strain between different trunk heights were not significant. Compared to the control group (no growth weakening treatment), growth weakening treatments significantly reduced growth strain one year later, with Treatment A and B reducing growth strain by 50% and 30%, respectively. Conclusion: The growth strain of C. hystrix is significantly influenced by tree characteristics such as dominance grade, season, tree age, trunk orientation, and meteorological factors such as humidity, temperature, and precipitation during the measurement months. Harvesting outside the summer season is beneficial for reducing growth stress in timber. The growth strain of C. hystrix was not significantly correlated with the height-diameter ratio of trees, and the regulation of tree density could not significantly reduce the growth stress. growth weakening treatments (ringbarking at the trunk base or injecting glyphosate growth inhibitor) can significantly reduce growth strain.

Objective: To simplify the method of testing Poisson’s ratio of wood and improve its testing accuracy, a cantilever beam 1/3-span patch method is proposed. Method: The 1/3-span patch method for square cantilever beams is proposed for dynamic testing of Poisson’s ratio of wood based on the stress and strain analysis of the first-order bending vibration of the beam. Firstly, for three cantilever beam specimens with square cross-sections in the main direction, naely Picea asperata, Pinus sylvestris and Fagus sylvatica, with length-to-thickness ratios of 8, 10, 12, 16 and 20, the ANSYS 19 modal program block was used to calculate the first-order bending modal stress and strain, and the absolute value of the ratio of the transverse strain to the longitudinal strain, $ -{\varepsilon }_{y}/{\varepsilon }_{x} $ along the central line $ x/l $ of the cantilever beam surface, that is, the curve $ -{\varepsilon }_{y}/{\varepsilon }_{x}-x/l $, and the position of the transverse stress $ {\sigma }_{y} $ = 0 were determined. Secondly, based on the change characteristics of the $ -{\varepsilon }_{y}/{\varepsilon }_{x}-x/l $ curve of the square cross-section cantilever beam, which is a straight line in the range of x/l = 0.2?0.7 and the $ -{\varepsilon }_{y}/{\varepsilon }_{x} $ value on it is equal to the corresponding reference value of the Poisson’s ratio of the wood in the principal direction, a 1/3-span patch method for testing the Poisson’s ratio of wood was proposed (the strain gauges were pasted at l/3 of the distance from the cantilever end of the specimen). Finally, the Poisson’s ratios of Larix gmelinii in the tangential direction (LT) and radial direction (LR), Picea sitchensis in the transverse direction (TR and TL), and laminated veneer lumber (LVL) in the longitudinal and transverse directions were dynamically tested by the 1/3-span patch method. Result: The effectiveness of the 1/3-span patch method for dynamic testing of the Poisson’s ratio of wood was verified by the symmetrically loaded four-point bending beam method and the axial tension method (the Poisson’s ratios of Larix gmelinii, Picea sitchensis and LVL tested by the three methods are very consistent); the consistency of the Poisson’s ratio of wood tested by the 1/3-span patch method and the $ {\sigma }_{y} $ = 0 patch method was demonstrated experimentally (the Poisson’s ratios of Larix gmelinii and Picea sitchensis tested by the 1/3-span patch method were quite consistent with the $ {\sigma }_{y} $ = 0 method). Conclusion: In addition to the advantages of simple test operation and high test accuracy, the 1/3-span patch method of cantilever beam with square cross-sections also uses three square section cantilever beam specimens to dynamically test the Poisson’s ratio of six main directions of wood, such as LT, LR, RT, RL, TR and TL, which is superior to the patch method of $ {\sigma }_{y} $ = 0 of cantilever plate specimens. This method uses square section cantilever wood beam specimens with length-to-thickness ratio of 8?20, which is suitable for testing the six main Poisson’s ratio of wood, and the patch position is independent of the main direction of wood and the specimen size.

Objective: The feasibility of accurately identifying wood species by integrating near infrared spectroscopy (NIR) and digital image feature information, automatically extracted based on convolutional neural networks (CNN), is investigated. Method: 10 wood specimens from the Lauraceae family were used as examples. NIR spectra and digital images from the transverse surfaces of specimens were collected using a handheld NIR spectrometer and portable scanner. The recurrence plot (RP) method was innovatively employed to encode one-dimensional (1D) NIR spectra as two-dimensional (2D) images. This not only enabled the CNN model to extract more robust discriminative features from the handheld NIR spectrometer’s shorter-wavelength NIR spectra, but also facilitated the fusion of NIR spectra and images. A simple two branch CNN (TB-CNN) model was developed to automatically extract and fuse NIR spectral and digital image features for wood species identification. Result: Compared to different modeling methods that utilize 1D NIR spectra directly, integrating 2D RP of NIR spectra with CNN resulted in a performance improvement ranging from 1.79% to 14%. Furthermore, when compared with the results obtained using a single feature from either NIR spectra or digital image, the TB-CNN method showed a significant increase in identification rates of at least 3%. Notably, the accuracy, precision and recall values all surpassed 99%. Conclusion: The conversion of 1D short-wavelength NIR spectra into RP enhances the ability of CNN model to extract more discriminative features from the NIR spectral data, improving model performance in species identification. The TB-CNN model effectively extracts and integrates wood NIR spectra and digital image features, addressing the limitations of using a single feature type for wood species identification and improving overall identification accuracy.

Objective: The article intends to carry out ecological product endowment analysis in the ecological space of Hulunbuir City and design optimized value realization pathways by combining comparative advantage analysis results with factual exploration situations, to realize the composite and coordinated development of the regional society, economy and ecology. Method: Based on the value of typical ecological products in four categories of water conservation, biodiversity con servation, carbon sequestration and ecological wellness functions in 13 counties (cities and districts) of Hulunbuir City, and combined with the citywide and regional GDP, through the resource endowment analysis method to calculate endowment factors and analyse the comparative advantages of each county (city and district). Result: The results of the endowment analysis are consistent with the distribution of ecological space areas. Genhe City, Erguna City, and Oroqen Autonomous Banner all have strong comparative advantages of four typical ecological product endowments, benefiting from larger forest and wetland distribution areas. However, the regional economic development of the above counties (cities) is relatively lagging, with GDP ranking in the middle and lower parts of the city, which shows the incongruity between the stock of ecological resources and the economic situation. The dynamic monitoring, value accounting system, and the design of value realization pathways of Hulunbuir City are still in the initial stage, the hidden added value provided by ecosystem services has not been well measured and manifested. Based on the analysis of resource endowment and obstacles related to value realization, four feasible optimization pathways are proposed: precise and quantitative compensation for forest ecological benefits; establishment of diversified ecological protection compensation mechanisms; construction of green financial service system; promotion of ecological industry development. Conclusion: Through a variety of measures to turn ecological values into economic advantages, promoting the comprehensive and sustainable development of lagging regions, and providing a scientific decision-making basis to improve the capacity of ecological products in forest, grassland and wetland ecological spaces and to solve the problem of the lack of coordination between ecology and development in the region.

Mongolian Scots pine (Pinus sylvestris var. mongolica) is an important tree species for ecological protection forests in China. Its natural forests are mainly distributed on the northern slopes of the Greater Khingan Mountains and the Hulunbuir Sandy Land. The introduced plantations have spread nearly the whole northern China, becoming the main evergreen and arbor tree species for the construction of windbreak and sand-fixing plantations in the Three-North Project of China. The natural Mongolian Scots pine forests are well naturally regenerated, but most of the artificial forests planted for sand-fixation generally have poor or totally failed natural regeneration. Moreover, the continuous global climate changes have exacerbated the uncertainty for the natural regeneration, which has become the threat and the major hidden danger to the stability and long-term services of the Three-North Project in China. This article systematically summarizes the domestic and foreign research results on the natural regeneration of both Mongolian Scots pine and its original species, Scots pine (Pinus sylvestris), and analyzes the effects and principles of key factors such as seed tree characteristics, habitat characteristics and natural interference that affect the natural regeneration process. Based on the comparison with the natural forest regeneration process, the five key stages of natural regeneration of Mongolian Scots pine plantations are divided, and the mechanism by which abiotic factors and biotic factors at each stage jointly affect the natural regeneration process are clarified. Finally, in response to changing the underground, surface, and above ground environmental conditions of forest land, three measures, including soil preparation, surface burning, and umbrella protection, are respectively proposed to regulate the progress of natural regeneration through artificial intervention. The study provides a new perspective for promoting the generational renewal of the Mongolian Scots pine plantations in the Three-North Project of China.

The exploitation and utilization of secondary metabolites of forest source is an important approach to play the forest as "treasure houses". Natural forest-derived flavonoids from Citrus aurantium which exhibit significant biological activities have been widely used in the fields of food and medicine. However, some bottleneck problems such as low resource utilization rate, unclear bioactivity mechanism, poor water solubility and low bioavailability, seriously restrict the sustainable development of the industry. This paper reviews the extraction, bioactivity and modification of flavonoids from Citrus aurantium. The extraction methods of the flavonoids were reviewed, while the strategies to strengthen the quality transfer process and the extraction mechanism were proposed. The main biological activities and potential mechanisms of the flavonoids were introduced, and the strategies to increase the flavonoids utilization value through chemical structure modification or embed technology were summarizeed. Meanwhile, the suggestions for future research were proposed. 1) The multi-extraction technology or multi-component extraction methods can be utilized to achieve efficient extraction of the flavonoids to improve the utilization efficiency of resources, and the migration behavior of substances during the extraction process may be revealed with the help of mass transfer models and characterization techniques. 2) The structure-activity relationship between chemical structure and biological activity can be further studied by means of experiment combining with computational chemistry to expound biological activities and their mechanisms. 3) The computational chemical methods can be used to accurately design modification strategies and interpret modification machines to modify the flavonoids.

Adhesives can make small-sized wood material unit into wood-based panels, plywood, and glued wood forms, which are used in engineering materials such as wood-frame buildings, load-bearing walls, decorative flooring, and bridges. The important basis for evaluating the gluing ability of adhesives is the gluing performance, which mainly includes the distribution of glue application, penetration ability, shear strength test, peeling test, wood breakage percentage measurement, and other indicators. With the popularization of machine vision technology, it has been applied as an important technique to assist in the evaluation of gluing performance. In order to have a more comprehensive understanding of the gluing performance measurement technology of machine vision, this paper outlines the image acquisition technology, image pre-processing technology, image segmentation technology, and calculation methods of machine vision technology on the basis of collecting domestic and foreign gluing performance measurement technology research literature. Secondly, it discusses the application of machine vision technology in the three aspects of adhesive sizing, adhesive permeability, and wood breakage percentage of glued surfaces. At the same time, the problem that machine vision technology can not segment digital image accurately, resulting in poor measurement accuracy is discussed. Finally, the optimization method of adhesive property measurement technology based on machine vision technology is summarized, and future research prospects are proposed: 1) to achieve accurate identification of adhesives and wood materials on adhesive joints, especially the identification of light-colored adhesives and substrates, especially the glue points and small wood units of particleboard and fiberboard; 2) Deeply explore the pixel-level unit characteristics of different measurement objects and the measurement mechanism of machine vision; 3) Research on scientific, sound and systematic evaluation mechanism based on machine vision technology; 4) Explore the influence mechanism of environmental factors such as illumination conditions, acquisition equipment and sample placement on image quality; 5) Establish a gluing performance evaluation database to provide data sources for deep learning or in-depth analysis of gluing performance.

Objective: The forest ecosystem composed of tall trees plays an irreplaceable role in Giant Panda habitat. Since 1990s, forest in Mabian Dafengding Nature Reserve suffered from deforestation by forest industry enterprises, causing serious impacts on the habitat of Giant Pandas. With the implementation of forest conservation projects such as the Natural Forest Protection Project, the forest vegetation has gradually recovered. Understanding the process of forest recovery after logging provides a fundamental basis for formulating restoration measures for the Giant Panda habitat. Method: Based on Landsat satellite data, this study conducted an analysis using the Support Vector Machine (SVM) classification method and the moving window approach to examine changes in forest cover over a 40-year period before and after forest logging in the Mabian Dafengding Nature Reserve. Field surveys were also conducted to assess habitat fragmentation and connectivity. Result: The research findings indicate that the forest within the reserve experienced heavily logging, the forest area decreasing from 295km² to 230 km², followed by a gradual recovering to 274km² and reaching 277km² in recent year. With the forest area gradually approaching the pre-logging level, the recovery rate decreasing as well, moreover, small-scale illegal logging is still damaging forest restoration. The heavily logged areas are concentrated mainly along the Sichanglada-Jueluohuo fire prevention road and in the southwestern region of the Yonghong conservation zone and the northern area of the Mani conservation point, resulting in the highly connected forestland in the reserve being blocked and divided into three zones. Among these, the Sichanglada-Jueluohuo fire prevention road area is the most severely affected and representative. Early-stage restoration efforts in this area did not reach the requirements for suitable habitat for Giant Pandas, improvement is in need, area is suitable for experimenting with forest recovery and protection measures. Conclusion: Forest fragmentation is pronounced within the reserve, with distinct separations between different blocks. It is necessary and urgent to carry out habitat restoration which aim at Giant Pandas` original habitat, establish Giant Pandas` habitat corridor, and strengthen control measures.