In the context of global climate change, species composition, spatial structure, biodiversity, carbon sequestration, oxygen release and other functions of forest ecosystems are often affected by local or exotic pests and diseases. The effects of forest pests and diseases on ecosystem carbon sequestration are mainly concentrated in the following aspects: 1) The reduction of photosynthetic efficiency. When trees are damaged by pests and diseases, photosynthetic indicators such as photosynthetic rate, stomatal conductance and transpiration decrease, photosynthetic related genes are downregulated, and the dark reaction ability involved in photosynthesis is weakened or even inhibited due to the interference. 2) The decrease in photosynthate has an impact on both above and below ground ecosystems. When photosynthates decrease, trees themselves redistribute the sucrose in their bodies to meet the needs of forest metabolism. The root biomass, soil autotrophic respiration ability and long-term underground carbon sequestration of forest trees are all reduced due to the decrease of photosynthates. 3）Plant tissues are damaged, which affects the growth, reproduction and survival of the host, thereby reducing biodiversity, destroying forest structure and reducing functional redundancy. 4) After the forest ecosystem is disturbed by pests and diseases, the growth ability of surviving plants and the decomposition ability of microorganisms are affected for a long time, thus changing the carbon sequestration ability of the forest for a long time and increasing the carbon emissions of the forest stand. 5) Insects and microbes can speed up the decomposition of dead wood and release carbon. Wood-feeding insects can not only directly feed on and consume dead wood, but also indirectly affect the decomposition of dead wood through interactions with microbial communities. An increasing number of studies have shown that forest pests and diseases can reduce forest area, reduce carbon sequestration capacity and increase carbon flux, thus transforming forests from “carbon sink” to “carbon source”.

Objective: The bird audio pretraining model, constructed through a large number of audio-text pairs, can be used for zero-shot classification of audio with insufficient training samples by utilizing side information for species classification. This approach can reduce the burden of data collection and provide an effective theoretical basis for zero-shot classification of bird audio, aiding ecological monitoring and analysis of species distribution changes in open environments. Method: The taxonomic information reflecting the phylogenetic relationships of birds was used as side information for species class. The pretrained RoBERTa text encoder and acoustic embeddings of audio using the pretrained HTSAT audio encoder were used to extract semantic embeddings of the taxonomy, respectively. The contrastive learning methods were used to calculate the similarity between semantic and acoustic embeddings, and construct a contrastive language-audio pretraining model for birds (CLAP-Bird). Subsequently, zero-shot classification for bird audio was realized based on the side information for zero-shot classes and CLAP-Bird model. Result: The proposed method was trained and evaluated on a large imbalanced bird audio dataset containing 725 hours of recordings. The average F1_score obtained across five different test sets, each with 8 to 10 classes, was 0.289. Compared to baseline models that were used for bird scientific name, life history, and basic characteristics as side information for species class, the proposed model significantly improved the zero-shot classification performance for bird audio. Conclusion: The taxonomy of birds is served as side information for species class, which provides insights into the biological and genetic relationships about bird species, helps the model better understand the connections between bird sounds and improves the performance of zero-shot learning for bird audio classification. Moreover, the closer the taxonomic relationship between the training set and the test set, the better the zero-shot classification performance on the test set.

Objective: This study addresses the challenges of detecting forest pests, collected by pest monitoring lamps, that are characterized by high diversity, complex sizes, and dense occlusions. We propose a multi-scale pest detection algorithm (MPD-YOLO) aimed at improving the accuracy of forest pest detection, thereby providing a new technological path for monitoring and protection of pests in forest areas. Method: First, a dataset comprising images of forest pests from regions such as Beijing, Hebei, and Shanxi was constructed. This dataset includes 18 categories of forest pests from various scenarios, providing a robust foundation for algorithm training and evaluation. Second, to improve the detection of small pests, MPD-YOLO employs 3D convolutions to extract deeper scale-sequence features from small targets, and introduces a scale sequence feature fusion module to enhance the model’s sensitivity to small objects. Finally, to address the challenges posed by dense occlusions and the coexistence of multi-scale pests, the MPD-YOLO method incorporates a triple feature encoding effective long-range aggregation network. This module fuses features across different scales, enhancing the interaction between multi-layer feature maps and improving the model’s detection performance. Result: Extensive experiments were conducted on the constructed dataset under identical test conditions, and the MPD-YOLO method was compared with mainstream object detection algorithms (YOLO series, Faster R-CNN, etc.). MPD-YOLO demonstrated superior pest recognition accuracy, with F1-score and mAP of 88.43% and 91.92%, respectively, outperforming the second-best method, YOLOv8x, by 1.45% and 1.22%. Additionally, compared to the original YOLOv7 model, MPD-YOLO achieved improvements of 0.72% in F1-score and 2.8% in mAP, confirming its advantages in handling complex object detection tasks. Ablation studies further analyzed the contributions of the scale sequence feature fusion and triple feature encoding modules, validating the effectiveness of each design component. Conclusion: The proposed MPD-YOLO algorithm significantly improves the detection performance of multi-scale pests in complex environments, demonstrating high robustness in challenging detection tasks. This algorithm provides a novel technical pathway for forest pest monitoring and protection.

Objective: In this study, an improved tree species recognition model of ConvNeXt network was proposed by using a transfer learning strategy and introducing the SimAM attention module and ECA channel attention mechanism, so as to improve the efficiency and accuracy of tree species recognition work and solve the difficulties encountered in the recognition work. Method: The bark images of common 12 tree species were used as the research object, and the data were expanded by traditional data enhancement methods to prevent model overfitting. An improved ConvNeXt-based network was constructed using SimAM and ECA channel attention mechanisms: SA-ConvNeXt for enhanced feature extraction, E-ConvNeXt for enhanced weighting of important features, and ES-ConvNeXt combining the two. The effect of the dataset on the accuracy of the ES-ConvNeXt network before and after enhancement was tested. The recognition effects with the ES-ConvNeXt model were compared by using the Resnet34, Rennet50, GoogLeNet, Swin Transformer, Densenet121, and ConvNeXt networks. Result: SA-ConvNeXt and E-ConvNeXt achieved 95.14%±0.42% and 96.085%±0.235% accuracy, respectively. ES-ConvNeXt, which incorporates SimAm and ECA attention modules, achieved an accuracy of 97.445%±0.635% for the test on the augmented dataset, its recognition accuracy for a single tree species exceeded 93%, and the highest category accuracy reached 99.79%, making it the optimal solution. The model trained with expanded data had optimal accuracy and loss values for the validation set both in terms of speed of convergence and final stabilized values compared to the model trained using the original data. With the same dataset, the recognition accuracies using Resnet34, Rennet50, GoogLeNet, Swin Transformer, Densenet121, and ConvNeXt networks were 92.74%, 94.47%, 90.52%, 92.85%, 70.38%, and 94.72%, respectively, which were all lower than the 97.81% obtained by the new improved model (ES-ConvNeXt model), further illustrating the effectiveness of the improved ES-ConvNeXt model. Conclusion: Data enhancement is effective for model accuracy improvement, and on the data-enhanced dataset, the improved ES-ConvNeXt model can perform the tree classification task more accurately compared to the other models, and it also has better generalization ability on different tree species.

Objective: This paper explores the pattern of species diversity and its scale effects in the Changbai Mountain broad-leaved Korean pine forest based on the individual species-area relationship (ISAR) model. The objective is to gain a deeper understanding of the community structure and the mechanisms maintaining species diversity in broad-leaved Korean pine forests, and to provide a scientific basis for biodiversity conservation and forest management. Method: This study utilized vegetation survey data from a 40-hectare fixed monitoring plot of a broad-leaved Korean pine forest and employed the ISAR model to analyze the impact of target tree species on neighborhood species richness at scales of 0?50 m. The significance of these effects was tested using homogeneous and heterogeneous Poisson?s null models. Furthermore, all tree individuals were categorized by diameter at breast height (DBH) into small-diameter class (5 cm≤DBH<20 cm), medium-diameter class (20cm≤ DBH<40 cm), and large-diameter class (DBH≥40 cm). The impact of individuals of different diameter classes on neighborhood species richness was analyzed in detail, with significance tested using the heterogeneous Poisson?s null model. Result: 1) The species diversity in the neighborhoods of dominant tree species is relatively low. 2) Habitat filtering is not significant at the scale of 0?10 m but significantly affects community species diversity structure at the scale of 11?50 m. 3) Within the scale range of 0?30 m, different tree species exhibit different patterns at varying research scales. At the scale of 31?50 m, most tree species predominantly act as diversity neutral species. 4) Individuals of large, medium, and small diameter classes promote neighborhood species diversity at the scale of 0?10 m, with the small-diameter class having an effect extending up to 14 m. At the scale of 21?50 m, small and medium-diameter individuals mainly exhibit facilitative effects, while large-diameter individuals predominantly show neutral effects. 5) The diversity structure of species within different diameter classes differs at the scale of 0?20 m, influenced by diameter class. However, at the scale of 21?50 m, no differences are observed, with neutral species dominating across all diameter classes. 6) At the scale of 0?10 m, the asymmetric competitive effect of larger-diameter individuals on species within smaller-diameter in the neighborhood is not significant. Asymmetric competition becomes evident at the scale of 14?20 m, with the effect becoming more pronounced as the diameter difference increases. Conclusion: The species diversity pattern of the Changbai Mountain broad-leaved Korean pine forest community is jointly influenced by habitat filtering, tree species characteristics, diameter structure, and interspecific competition, exhibiting significant scale effects. In forest management, it is important to consider ecological processes at different scales, rationally configure tree species and diameter structures, promote species niche differentiation, and reduce asymmetric competition in order to enhance forest biodiversity and resource utilization efficiency.

Objective: As a special forest type in China, bamboo forest is susceptible to extreme climate. It is of great significance to examine the spatiotemporal patterns of extreme climate events in China’s bamboo forests, which can unveil the spatial differentiation and temporal change patterns and thus provide a reference to cope with extreme climate events in the future. Method: In this paper, based on the meteorological data from 1960 to 2020, we used the China Weather Generator (NCC/GU-WG Version 2.0) to forecast the meteorological data from 2021 to 2050, and calculate the commonly used 10 extreme climate indices related to bamboo growth by RClimDex software. Then accumulative anomalies, Sen trend, Mann-Kendall test, and Kriging interpolation were employed to study the spatiotemporal distribution of extreme climate and its change in China’s bamboo forests. Result: From 1960 to 2050, number of hot summer days, maximum values of daily maximum and daily minimum temperatures, minimum values of daily maximum and daily minimum temperatures increased by 3.52 d, 0.15 ℃, 0.21 ℃, 0.26 ℃ , and 0.4 ℃ every 10 years, respectively, while frost days decreased 1.79 d every 10 years, and the aforementioned extreme temperature indices had abrupt changes around 2000. Maximum daily precipitation, maximum five-day precipitation, heavy precipitation, and average annual daily precipitation intensity increased by 1.58 mm, 2.13 mm, 12.99 mm , and 0.2 mm?d^?1 every 10 years, respectively, and all the extreme precipitation indices had abrupt changes around 1994. Spatially, the low-value areas of maximum value of daily maximum and daily minimum temperatures representing extreme high temperatures, and high-value areas of frost days were mainly located in the monopodial bamboo areas at high inland latitude. The minimum value of daily maximum and daily minimum temperatures representing extreme low temperatures were larger throughout the region, the high-value areas of summer days were located in bamboo forest areas at low latitudes, and the high-value areas of extreme precipitation lied in the southern and coastal regions. Conclusion: Both temperature and precipitation extremes are significantly increasing in China’s bamboo forest. Monopodial bamboo areas located in high inland latitude might be vulnerable to extreme low temperature events, while the bamboo forest at low latitudes is more likely to suffer from both drought and flood disasters, and the mixed bamboo areas of Sichuan encountering extreme temperature and precipitation events are both relatively high.

Objective: Extract the spatial elements of various types of wetlands in in Suzhou central urban area, construct the wetland ecological network, quantitatively evaluate the resilience level of the wetland ecological network, and provide a scientific basis for the resilience measurement and spatial conservation planning of wetland ecological networks in water network city. Method: Taking the central urban area of Suzhou as an example, a water network urban wetland ecological network is constructed based on the “MSPA-Conefor-MCR-GM” model. The complex network analysis method is used to select indicators that can reflect the resilience characteristics and levels of the wetland ecological network. The resilience level of the wetland ecological network is quantitatively measured from three dimensions: structure, function, and composition, and key wetland patches and ecological corridors in the region are identified. Result: 1) 19 ecological source areas, 171 potential ecological corridors and 28 important ecological corridors were extracted from the central urban area of Suzhou, and 137 ecological nodes were identified, forming a typical network like multi cluster and multi node structural feature. Among them, ecological source areas exhibit spatial distribution characteristics of “multi center, multi cluster”, potential ecological corridors exhibit spatial distribution characteristics of“northeast-central dense network ,other regions exhibit minimal or negligible”, important ecological corridors exhibit spatial distribution characteristics of“northeast-southwest orientation, partially grid-like”, and ecological nodes form spatial distribution characteristics of “overall dispersion, local compactness”. 2) In terms of structural resilience, the average clustering coefficient of the wetland ecological network in the central urban area is 0.04, the average degree of the network is 3.12, and the scale-free characteristics are obvious. The aggregation is weak, the connectivity is average, and the structural resilience is insufficient. 3) In terms of functional resilience, the average path length, network efficiency value, average node structure hole value, and average k-core index value are 5.47, 0.19, 0.41, and 2.02, respectively. The average number of independent paths between nodes is still acceptable, and the network diversity is high. However, due to the impact of urban construction, the corridors between patches are relatively long, with insufficient transmission and stability, and weak collaboration. 4) In terms of component resilience, the node centrality range is 0?2 837.17, with an average value of 365.17, and the edge centrality range is 1?2 618.76, with an average value of 1 469.43. There are significant differences in the importance of plaques and corridors, with strong spatial heterogeneity and significant differences in component resilience levels. Conclusion: The resilience level of the wetland ecological network in the central urban area of Suzhou is generally average, with different characteristics and levels of structural resilience, functional resilience, and component resilience. The research results can serve as a baseline reference for wetland ecological protection and management in this area.

Objective: This study aims to clarify the changes in soil organic carbon components and the main influencing factors in both the rhizosphere and non-rhizosphere soils of citrus trees during the growth and natural decomposition seasons of green manure. The goal is to gain a better understanding of the mechanisms by which green manure cover affects soil carbon components in orchards, providing scientific evidence to support the promotion of green manure practices in orchard management. Method: Citrus orchards with and without smooth vetch cover (clean tillage treatment) were selected to measure the distribution of the particulate organic carbon, including free particulate organic carbon and occluded particulate organic carbon, as well as mineral-associated organic carbon in the rhizosphere and non-rhizosphere soils during the growth and decomposition seasons of the vetch. And the relationship between soil organic carbon components and plant characteristics (including the carbon, nitrogen, and phosphorus content of citrus fine roots, as well as annual carbon, nitrogen, and phosphorus input by vetch aboveground and fine root) and edaphic variables (free particulate organic nitrogen, occluded particulate organic nitrogen, mineral-associated organic nitrogen, total nitrogen, total phosphorus, clay content, and extracellular enzyme activity) were also analyzed. Result: Compared to clear tillage, vetch cover significantly increased (P<0.05) the occluded particulate organic carbon content in both rhizosphere (34.13% and 56.01%, respectively) and non-rhizosphere soils (33.02% and 64.23%, respectively) during the vetch growth and decomposition seasons. However, vetch cover also significantly decreased (P<0.05) mineral-associated organic carbon content in both rhizosphere (?12.56% and ?19.72%, respectively) and non-rhizosphere soils (?13.10% and ?20.67%, respectively) during the both seasons. During vetch growth season, free particulate organic carbon content was significantly increased (P<0.05) in non-rhizosphere soils (78.77%) but decreased in rhizosphere soil (?8.48%). Conversely, during vetch decomposition seasons, free particulate organic carbon content was decreased in non-rhizosphere soil (?18.66%, P<0.05) and increased (18.62%, P<0.05) in rhizosphere soil. Redundancy analysis showed that in citrus orchard with vetch cover, the content of free particulate organic carbon and occluded particulate organic carbon in the soil was significantly (P<0.05) positively correlated with the annual carbon and nitrogen inputs from vetch fine roots, as well as with the soil’s occluded particulate organic nitrogen, total nitrogen, and clay content. Additionally, soil mineral-associated organic nitrogen content was significantly (P<0.05) positively correlated with mineral-associated organic carbon content. Variance partitioning analysis indicated that vetch cover increased the joint effect of plants and soil factors on soil organic carbon components (from 18.3% to 33.9%). Hierarchical partitioning further identified that soil mineral-associated organic nitrogen was the primary factor responsible for the reduction of mineral-associated organic carbon, while occluded particulate organic nitrogen, the annual carbon and nitrogen input from vetch fine roots, and soil clay content were the main factors effect on the accumulation of soil free particulate organic carbon and occluded particulate organic carbon. Conclusion: Vetch cover promotes the accumulation of soil particulate organic carbon by carbon and nitrogen released by its fine roots, as well as the regulation of soil mineral-associated organic nitrogen content. This process offsets the loss of soil mineral-associated organic carbon, ultimately resulting in a net increase in soil organic carbon of citrus orchards. This study highlights the ecological benefits brought by green manure cover and provides a scientific basis for promoting green manure practices in fruit orchards.The ecological benefits brought by green manure cover make it one of the management practices for enhancing the carbon potential of orchards.

Objective: Taking natural mixed conifer-broadleaved forests in Changbai Mountains as the research object, this study proposes four estimation methods of stand dominant height and the corresponding calculation methods of site form (SF), compares the differences among various dominant height estimation methods, and analyzes the relationship between dominant height and stand factors in order to determine a reasonable estimation method for stand dominant height in mixed forests and to evaluate the applicability of site form for assessing site quality. Method: Totally 127 sample plots of natural mixed conifer-broadleaved forests were investigated and analyzed at Bajiazi Forestry Bureau of Jilin Province. The height, diameter at breast height (DBH) and age of six dominant trees (three conifers and three broadleaves) were measured in each sample plot. Dominant heights were estimated using four different methods based on weighted averages, and these included the unweighted arithmetic mean height of all dominant trees (H_T1), the basal area-weighted mean height considering both conifer and broadleaf trees (H_T2), the basal area-weighted mean height considering only dominant tree species (H_T3), and the basal area-weighted mean height considering all species within a plot (H_T4). The corresponding mean DBH of dominant trees (D_T1, D_T2, D_T3, D_T4) and the mean age of dominant trees (A_T1, A_T2, A_T3, A_T4) for a plot were also calculated using four different methods. Through correlation analysis and paired t-tests, differences among the four methods of estimating dominant height were compared. The study further analyzed the relationships between these dominant heights (H_T1, H_T2, H_T3, H_T4) and stand density, productivity, mean DBH of dominant trees, and mean age of dominant trees. Power function, Hossfeld II, and Richards’ equations were selected as candidate models describing the mean height-DBH relationship of stand dominant trees. The final model was determined according to model evaluation indices. The reference diameter was the rounded value with most frequency of diameter distribution of dominant trees, and the site form was derivated using the height-diameter model and the reference diameter. By comparing the relationships between the site forms corresponding to different dominant heights and stand factors, the optimal methods for estimating dominant height and calculating site form in natural mixed conifer-broadleaved forests were determined. Result: Significant correlations were found among the four methods of dominant height estimation. H_T1, H_T2, and H_T3 showed high correlation coefficients above 0.96, with no significant differences. However, H_T4 demonstrated the lowest correlation with the other three methods and there was a significant difference between H_T4 and the other three methods. The basal area-weighted mean height considering all tree species within a plot H_T4 showed no significant correlation with three stand density indicators (stand basal area, stem number, additive stand density index). Furthermore, H_T4 and its corresponding diameter (D_T4) and age (A_T4) showed the highest correlation coefficients of 0.815 and 0.657, respectively. The correlation coefficients between H_T3 and its corresponding D_T3 and A_T3 were 0.420 and 0.227, respectively. The models for H_T3-D_T3 and H_T4-D_T4 were established using Power and Richards equations, respectively, with adjusted determination coefficients (R_a²) of 0.16 and 0.68. Based on the most frequent DBH of dominant trees in the sample plots, the reference DBH was set as 30 cm after rounding. The corresponding site forms, S_F,T3 and S_F,T4, were then determined using guide curves. Among the two site forms, only S_F,T4 showed no correlations with additive stand density index, while both S_F,T3 and S_F,T4 were significantly related to stand productivity, with correlation coefficients of 0.224 and 0.264, respectively. Conclusion: The basal area-weighted mean height considering all tree species within a plot (H_T4) performed the best, and the site form (S_F,T4) calculated from the dominant height showed significant correlations with site productivity, making it suitable for assessing site quality in natural mixed conifer-broadleaved forests.

Objective: This study aims to develop models for tree crown width(CW) and stand density(SD), as well as a combined model integrating both. By exploring the correlation between CW model and SD model, this research provides a scientific basis for further studies on stand density management and guidance for forest management practices. Method: Using the measurement data of 600 representative sample trees of larch collected throughout the whole country of China, and the data of 1273 permanent plots in natural larch forests from the 9^th national forest inventory, the CW model and the SD model of larch were established by using nonlinear regression and logarithmic regression estimation methods. Based on the analysis of the relationship between CW model and SD model, a multivariate nonlinear regression method with dummy variables was used to establish the simultaneous models, and the maximum stand density line was determined. Result: The results showed that CW was positively correlated with diameter at breast height (DBH); the determination coefficient R² of CW model for larch was higher than 0.76, the standard error of estimate (SEE) was 1.03 m, and the mean prediction error (MPE) was 2.16%. The ratio of CW-DBH decreased with the increase of DBH, from 0.53 at 2 cm to 0.23 at 20 cm and then slowly to 0.17 at 50 cm. The SD was negatively correlated with mean DBH; the R² of SD model for larch forests reached to 0.88, the SEE was 147 stems per hectare, and the MPE was 2.58%. There was a 2-fold negative correlation between the two power parameters of SD model and CW model, and the slope parameter from the simultaneous models is ?1.384, which can be regarded as the average value of the slopes of self-thinning lines of natural larch forests in China. Conclusion: It is a feasible new approach to use multivariate regression method for estimating the slope parameter of the stand density index (SDI) based on the correlation between SD model and CW model. This is of practical significance to study the SDI of other tree species and to guide the stand density management and forest scientific management.

Objective: This study aims to investigate the phenotypic traits of Ziziphus jujuba var. spinosa fruit in the eastern Taihang Mountains and the environmental driving factors, and to screen out excellent Z. jujuba var. spinosa production areas, so as to provide a scientific basis for the development and utilization of jujube resources. Method: A total of 38 sampling sites with 152 plots were set up in the eastern Taihang Mountains, and the site conditions including altitude and soil pH were assessed. Z. jujuba var. spinosa fruits were collected from each plot, and their phenotypic traits (vertical and horizontal diameters, fruit mass, nutlet, kernel, etc.) were measured. Result: 1) There were significant differences in the phenotypic traits of Z. jujuba var. spinosa fruits among different regions (P < 0.01). Notably, kernel mass (20.86%), kernel rate (19.63%), fruit mass (13.72%), and fresh fruit edible rate (13.35%) had the higher inter-regional variability coefficients. There were correlations among various phenotypic traits. Specifically, the kernel rate showed a highly significant negative correlation with fruit vertical diameter, fruit horizontal diameter, and fruit mass (P < 0.01). 2) Environmental factors were able to explain 56.7% of the variation in the phenotypic traits of Z. jujuba var. spinosa fruits. Altitude (14.2%), latitude (11.8%), soil pH (4.2%), soil moisture content (3.9%), and soil bulk density (3.2%) were the main environmental factors influencing these traits. The kernel rate was significantly positively correlated with altitude (P < 0.01), but significantly negatively correlated with latitude, longitude, and soil moisture content (P < 0.01). Fresh fruit edible rate was significantly negatively correlated with latitude, altitude, longitude, and soil sand content (P < 0.01), and significantly positively correlated with annual average temperature and effective accumulated temperature (P < 0.01). 3) Based on the phenotypic distribution characteristics of Z. jujuba var. spinosa fruits, "fruit-use type" production sites were identified in Boai County and Zanhuang County; "kernel-use type" production sites were found in She County and Linzhou City; "fruit- kernel dual-use type" production sites were located in Yuquanshan Mountain within Xindu District of Xingtai City and Zanhuang County. Conclusion: There is a strong correlation among different phenotypic traits of Z. jujuba var. spinosa fruits, and the kernel rate, and fresh edible fruit rate can serve as important reference indicators in variety breeding and improvement. Phenotypic traits of Z. jujuba var. spinosa, such as kernel rate and fresh edible fruit rate, are greatly influenced by environmental factors. Adjustment of temperature, soil pH, and soil moisture content can be considered as one of the method to increase Z. jujuba var. spinosa kernel and pulp yield.

Objective: This study aims to establish the optimal detection and hydrolysis conditions for the 3,5-dinitrosalicylic acid method, in order to accurately determine the content and its variation of arabinogalactan in the xylem of Larix kaempferi, and provide technical support for deeply understanding the distribution, development, and biosynthesis of arabinogalactan in the xylem of L. kaempferi. Method: The optimal detection conditions of 3,5-dinitrosalicylic acid method were determined by analyzing the three aspects of coloration reagent volume, reaction time, and reaction temperature. At the same time, an orthogonal test was used to optimize the hydrolysis conditions of total sugar from three aspects of hydrochloric acid concentration, hydrochloric acid volume and hydrolysis time. The contents of total sugar and reducing sugar were measured, respectively, with which the polysaccharide content was calculated. Result: The optimum detection conditions of the 3,5-dinitrosalicylic acid method were established. The coloration reagent volume, reaction time, and reaction temperature were 5 mL, 9 min, and 90 ℃, respectively. The optimal hydrolysis conditions were hydrochloric acid concentration of 6 mol·L^?1, hydrochloric acid volume of 15 mL, and hydrolysis time of 40 min. In individual L. kaempferi trees, the content of arabinogalactan in xylem gradually decreased with the increase of tree height in the axial direction, and was much lower in the sapwood than that in the heartwood in the radial direction. Overall, the arabinogalactan content in heartwood area gradually increased outward with the growth ring, while the arabinogalactan content in the sapwood area gradually increased inward the growth ring. The arabinogalactan content was highest in the transition zone between sapwood and heartwood, the arabinogalactan content in springwood was much higher than that in summerwood within each growth ring, and the arabinogalactan content in earlywood was much higher than that in latewood within the transition zone. Conclusion: In this study, a simple and stable method for accurately detecting the content of arabinogalactan without relying on high-quality samples has been established. At the same time, it has been found that arabinogalactan content is highest in the basal trunk, and is higher in the heartwood than in the sapwood, and higher in the springwood than in the summerwood, and highest in the transition zone, suggesting that the arabinogalactan may be synthesized in the transition zone and related to the formation of heartwood.

Objective: This study aims to investigate the effects of different anti-vibration packaging materials on the shelf-life quality of kiwifruit during the storage and transportation of ‘Xu Xiang’ kiwifruit, as well as the effects of expanded polyethylene (EPE) packaging treatment on the activity of relevant enzymes and gene expression during the malic acid metabolism of kiwifruit after harvest. Method: Three kinds of anti-vibration packaging treatments, namely, foam mesh bag packaging, expanded polystyrene (EPS) and expanded polyethylene (EPE), were adopted, and road transportation was simulated in a 72 h vibration experiment on a vibration test bench. The shelf-life qualities of kiwifruit (hardness, color, and the contents of titratable acid, soluble solids, vitamin C and total phenol) were determined. Then, the indicators of cell membrane damage (malondialdehyde, relative conductivity and lipoxygenase activity) were analyzed, and the activity and gene expression of enzymes involved in malic acid metabolism were measured and the correlation among the measured data was investigated. Result: Compared with the foam mesh bag and EPS packaging, the EPE packaging maintained the hardness and color of kiwifruit fruits, promoted the synthesis of saccharides, and inhibited the decomposition of antioxidants. It also slowed down the rise of relative conductivity and malondialdehyde content, reduced lipid peroxidation and maintained the integrity of cell membranes. Furthermore, results showed that malic acid content was positively correlated with synthesis-related NAD-MDH and PEPC enzyme activities, and negatively correlated with degradation-related NADP-ME enzyme activities. EPE packaging stabilized the malic acid metabolism-related enzyme activities and gene expression. Conclusion: EPE anti-vibration packaging treatment is beneficial to the maintenance of shelf-life quality of kiwifruit fruit during storage and transportation. It exhibits a positive effect on malic acid metabolism of kiwifruit fruits.

Objective: The NAC transcription factor plays a pivotal role in plant, specifically in regulating secondary cell wall (SCW) development. In this study, we cloned a NAC gene associated with SCW development in Cunninghamia lanceolata and conducted an extensive investigation into its bioinformatics characteristics, expression patterns, and the effects of overexpression in Arabidopsis thaliana. This study aims to provide important reference value for elucidating the molecular mechanisms underlying SCW development and facilitating molecular-assisted breeding in C. lanceolata. Method: Based on the transcriptome sequencing data from different organs and tissues of C. lanceolata, a co-expression network analysis was conducted to identify the NAC gene associated with lignification. Subsequently, the full-length sequence of this gene was cloned and subjected to sequence alignment and phylogenetic tree analysis. Real-time quantitative PCR (RT-qPCR) was used to investigate its expression patterns in different tissues and during the process of compression wood formation. Furthermore, an overexpression recombinant vector for the NAC gene was constructed and transformed into A. thaliana via inflorescence infestation. The cross sections of the inflorescence stem from transgenic plants were stained, and the expression of key enzyme genes involved in lignin biosynthesis was analyzed. Result: A ClNAC40 gene was isolated from C. lanceolata, with the cDNA sequence length of 1 556 bp and an open reading frame (ORF) of 1 344 bp that can encode 447 amino acids. A total of 3 430 bp of the ClNAC40 genome sequence was obtained, consisting of six exons and five introns. Evolutionary tree analysis revealed that ClNAC40 was clustered with the reported NAC transcription factors involved in SCW formation. The ClNAC40 was predominantly expressed in xylem (XY), while it exhibited relatively lower levels in root (RT), female cone (FC), male cone (MC), and bark (BK). Additionally, the expression in the stems was positively correlated with the degree of lignification, with a 3.2-fold increase in expression level observed in lignified stems (S3) compared to non-lignified stems (S1). During the formation of compression wood, the expression of ClNAC40 was upregulated, with significantly higher levels observed in compression wood compared to upright wood after 30 and 60 days of oblique treatment. The overexpression of ClNAC40 in A. thaliana resulted in a significant enhancement in plant height and inflorescence stem diameter. Subsequently, the phloroglucinol staining of the cross section of the inflorescence stem exhibited a deeper color compared to the wild type, accompanied by a larger staining area, indicating an increase in lignin deposition. The RT-qPCR analysis showed that the overexpression of ClNAC40 significantly upregulated the expression of key enzyme genes involved in the lignin biosynthesis in A. thaliana. Conclusion: The ClNAC40 in C. lanceolata participates in regulating SCW development by activating the transcription of lignin biosynthesis-related enzyme genes.

Objective: The aim of this study is to investigate the adaptation of seedling traits in the progeny of poplar hybrids under low nitrogen stress, and to screen for excellent genotypes with strong low nitrogen tolerance, in order to provide theoretical basis for breeding new poplar varieties with fast growth and strong adaptability to low nitrogen environment. Method: Using the potting method in greenhouse, a total of 226 hybrids from the crossing between Populus simonigra and P. nigra were used as experimental material to determine growth, leaf morphology, chlorophyll fluorescence parameters and nitrogen isotope parameters traits under low nitrogen (LN) and normal nitrogen (NN) treatments. The Restricted Maximum Likelihood/Best Linear Unbiased Prediction (REML/BLUP) based on the linear mixed model was used to analyze genetic variation and the estimation of genetic parameters including breeding values. The multi-trait selection based multi-trait genotype-ideotype distance index (MGIDI) was used to rank the genotypes of the hybrid progeny and to comprehensively evaluate the adaptability of the hybrid progeny to the experiment. Result: The mean values of growth and leaf morphological traits differed significantly between the two groups of N supply levels, with LN﹤NN. For most of these above traits, the genotype effects were significant among the progeny, and the interaction effect (G × E) between genotype and nitrogen-supplying treatment environment was extremely significant, whereas neither genotype effects nor G × E effects were significant for chlorophyll fluorescence parameters. Broad sense heritability ($ {h}_{\mathrm{g}}^{2} $), mean heritability ($ {h}_{\mathrm{g}\mathrm{m}}^{2} $), and coefficient of genetic variation (CV_g) of the traits were less than 0.38, 0.56 and 22.30%, respectively. The principal component analysis (PCA) was conducted on the breeding values of growth and morphological traits, as well as the observed values of nitrogen isotope parameters. The first four principal components (FA) with their eigenvalues above 1 were extracted for factor analysis, accounting for 84.10% of total variance. The four factors (FA1, FA2, FA3 and FA4) of the factor analysis reflected the information on growth, leaf morphology, nitrogen isotope composition and nitrogen isotope content, respectively. The multi-trait index, MGIDI, was obtained to rank the genotypes of the progeny. The top 42 genotypes of the progeny were selected at a selection intensity of 20% with genetic gains for the traits ranging from 2.0% to 16.50%, of which 7, 8, 7 and 3 genotypes showed dominance for growth, leaf morphology, nitrogen isotope combinations and nitrogen isotope content, respectively. Conclusion: The seedling growth, leaf morphology and physiological traits of the poplar hybrid progeny are significantly inhibited under low nitrogen stress. The growth traits and leaf morphological characteristics are significantly influenced by genetic factors and their interactions with the environment. The genotypes selected by the comprehensive evaluation of multiple trait indices have strong adaptation to low nitrogen stress and can be used for selection of new poplar varieties with low nitrogen tolerance.

Objective: The phylogenetic relationship of 80 Metarhizium strains isolated from domestic and abroad and their virulence to Monochamus alternatus adult were investigated in order to screen highly virulent strains for the control of M. alternatus adult. Method: The ITS1/ITS4 and T1/T22 primer pairs were used to amplify the ITS region and β-tubulin gene sequences of 80 Metarhizium strains, respectively. MAFFT was used to align the sequences, and the phylogenetic tree was constructed using the maximum likelihood method and the Bayesian method with IQ-TREE and Mrbayes 3.2.7 software. The virulence of Metarhizium strains was determined using M. alternatus adults in 1-3 days after emergence. Metarhizium strains were cultured on PDA medium, and the spores were collected and prepared into a spore suspension with a concentration of 10⁷·mL^?1 using 0.05% Tween 80 solution, and 0.05% Tween 80 solution was used as a blank control. The impregnation method was used to treat M. alternatus adults, and the pathogenicity of the strains was evaluated by using the cumulative corrected mortality rate of M. alternatus adults. Result: Among the 123 strains collected from domestic and international libraries, there are 80 strains of Metarhizium, which are divided into 6 major taxa, including 57 strains belonging to M. anisopliae species complex, 11 strains belonging to M. flavoviride species complex, 6 strains belonging to M. rileyi, 4 strains belonging to M. viride, one strain belonging to M. cylindrosporum, and one strain belonging to M. novozealandicum. The highly virulent strains were mainly found in M. anisopliae species complex and M. flavoviride species complex. M. acridum, M. cylindrosporum, M. novozealandicum, M. rileyi, and M. viride did not show pathogenicity against M. alternatus adults. A total of 14 strains of Metarhizium were highly virulence (LT₅₀< 15 d, 15-day adjusted mortality >80%), which can be used as alternative strains for the control of M. alternatus. Conclusion: Based on the phylogenetic and virulence test results of 80 strains of Metarhizium from domestic and international, strains with high virulence against M. alternatus adult have been screened, among which 14 strains have high application potential. The phylogenetic relationships of Metarhizium are established, and the distribution of highly virulent strains against M. alternatus adult is confirmed.

Objective: The aim of this study was to investigate the effects of temperature on the bending mechanical properties of Phyllostachys edulis, providing data support and a theoretical basis for its structural application in extreme environment conditions. Method: Bamboo samples aged 3–6 years from Chishui City, Guizhou Province, were used to prepare two types of specimens: with nodes and without nodes, with 66 specimens of each type. Eleven target temperatures (?60, ?40, ?20, 0, 20, 60, 100, 130, 175, 185, and 200 ℃) were set for three-point bending tests to measure the bending strength and bending elastic modulus of the bamboo. The effects of temperature on bending mechanical properties were analyzed. Correlation analysis was conducted to explore the relationships between temperature, bending strength, and bending elastic modulus. Quadratic function equations were proposed for the temperature impact coefficients of bending strength and bending elastic modulus. Microscopic structural observations were conducted to examine changes in bamboo cell walls at low and high temperatures, revealing the intrinsic mechanisms behind the changes in bending mechanical properties. Result: Temperature has a significant impact on the bending mechanical properties of Phyllostachys edulis. As the temperature increases, both the bending strength and bending elastic modulus exhibit a pronounced declining trend. At 200 ℃, the bending strength of specimens with and without nodes is reduced to 31% of the bending strength at room temperature (20 ℃), while the bending elastic modulus decreases to 44% and 41% of the corresponding room temperature values. Conversely, at ?60 ℃, the bending strength of specimens with and without nodes increases to 116% and 115% of the bending strength at room temperature, while the bending elastic modulus rises to 135% and 128% of the room temperature values, respectively. Under low-temperature conditions, Phyllostachys edulis exhibits higher strength but pronounced brittleness, whereas under high-temperature conditions, it demonstrates lower strength and increased plastic deformation. The presence of nodes had little effect on bending strength, with no significant difference observed between specimens with and without nodes under either low or high temperatures. However, nodes have a significantly adverse impact on the bending elastic modulus, particularly within the temperature range of ?40 ℃ to 130 ℃. Microscopic structural analysis revealed that under low-temperature conditions, the bamboo cell walls remain intact and tightly compacted, which contributes to enhanced mechanical performance. Under high temperatures, due to moisture evaporation and chemical composition transformation, bamboo cell walls softened and gradually thinned, resulting in a significant decline in mechanical properties. Conclusion: Our results demonstrated that the bending mechanical properties of Phyllostachys edulis under extreme environment conditions are significantly influenced by temperature variations. Low temperatures enhance the strength of Phyllostachys edulis but increase its brittleness, while high temperatures weaken its strength and promote greater plastic deformation. Our findings showed that the presence of nodes has minimal impact on bending strength but exerts a noticeable adverse effect on its elastic modulus.

Objective: In the present work, the evolution of ash composition and transformation mechanism was interpreted in details. Importantly, the distribution pattern of silicon in internodes and nodes as well as the effects of gradient pyrolysis on the silicon deposition will be investigated. The above results will provide theoretical and data support for the development of efficient ash removal process as well as the production of high purity bamboo charcoal and bamboo activated carbon. Method: One-year-old moso bamboo (Phyllostachys edulis) was selected, and SEM-EDXA, XRF, XRD and other analytical techniques were used to study the changing rules of ash content and composition in different parts of bamboo (internodes, nodes, inner bark, outer bark and stomata) under the gradient pyrolysis conditions (350, 500, 800, and 1 000 ℃). Also, the combination of all these techniques were used to explore the distribution of silicon in the various parts of bamboo (inner and outer bark, stomata, bamboo green, bamboo timber, and bamboo yellow) and the effects of the pyrolysis treatment on the silicon distribution. Result: The ash of bamboo mainly consisted of CaO, K₂O, SiO₂, Al₂O₃, and certain sulfur oxides (SO₃) and phosphorus oxides (P₂O₅). XRD analysis showed that the ash of bamboo internodes was mainly composed of KCl, K₂SO₄, KAlSiO, KFeSiO₄, etc. In addition to the above inorganic salts, there were obvious crystalline SiO₂ characteristic peaks in the internodes. Silicon-containing inorganic salts, such as KAlSiO, and KFeSiO₄ were generated and short-range order of turbostratic stacks in bamboo charcoal occured when the pyrolysis temperature reaches 800 ℃ Higher silicon content was observed in the bark and stomata for both internodes and nodes. Besides the parenchyma near the epidermis containing silicon particles, the parenchyma located in bamboo timber and yellow also existed micrometers silicon oxides. The relative content of silicon reached the maximum at 500 ℃, while the relative content of silicon began to decrease at 800 ℃ with the generation of silicate and aluminosilicate. The relative content of potassium showed a linear increase throughout the pyrolysis process. High-temperature heat treatment caused the volatilization of elements such as H and O, the consumption of carbon, resulting in the release of silicon which were deposited in the lumen of the vessel and parenchyma. Conclusion: 1) Bamboo nodes and internodes displayed the similar ash composition, while the internode parts had a higher silicon content. Silicon was widely distributed in the bamboo outer bark, stomata and parenchyma adjacent to bamboo green. 2) The relative content of CaO and K₂O in the nodes and internodes displayed the maximum value when the pyrolysis temperature reached 500 ℃ Increasing the pyrolysis temperature to 800 ℃ converted these inorganic salts into silicate and aluminosilicate. 3) High-temperature treatment caused the release of silicon in the internodes, which was deposited in the lumen of vessel and parenchyma.

Objective: A numerical model of tire-soil interaction for the typical unsaturated red soil environment of southern forests in China is proposed. Based on the model, the impact of tire size parameters on the driving performance of small wheeled mobile platforms in forest is analyzed. This research provides a theoretical basis for optimizing tire size parameters for small wheeled mobile platforms to enhance the maneuverability. Method: The commonly used rubber tires of small wheeled mobile platform are investigated in this paper. Physical parameters of the rubber tires are determined through uniaxial tensile test. An accurate tire model is constructed using the finite element software Abaqus. In addition, unsaturated red soil samples from southern forests are collected. Physical and mechanical properties are identified through measurements and triaxial compression tests. A precise model of the unsaturated red soil is established using the discrete element software PFC3D. As a result, a novel numerical model of tire-soil interaction for the typical unsaturated red soil environment of southern forests in China is established by integrating the finite element method and the discrete element method. The approach overcomes the limitations of using either the finite element method or the discrete element method individually. Significantly, the numerical model is used to simulate the impact of tire diameter (D = 65, 75, 85 mm), width (W = 20, 25, 34 mm), and diameter-to-width ratio (D/W = 2.2, 2.6, 3.0, 3.4, 3.8) on the drawbar pull and tire sinkage. Furthermore, soil-bin tests, consistent with the simulation analysis, are established to validate the effectiveness of the numerical model and the accuracy of the analysis regarding the impact of tire size parameters on the driving performance of small wheeled mobile platforms. Result: 1） The drawbar pull shows an increasing trend with the increase in tire diameter and width. 2） The tire sinkage shows a decreasing trend with the increase in tire diameter and width, but beyond a certain range, the influence of tire diameter and width on sinkage diminishes. 3） The comprehensive indicator of tire diameter and width, the diameter-to-width ratio (D/W), has a significant impact on the drawbar pull and sinkage. Among the simulation and experimental data, a D/W ratio of 2.2 provides the maximum drawbar pull and the minimum sinkage, demonstrating the optimal driving performance. Conclusion: The research accurately establishes a numerical model of tire-soil interaction for the typical unsaturated red soil environment southern forests in China. The model can be used to analyze the impact of tire size parameters on the driving performance of small wheeled mobile platforms. Additionally, the research provides a scientific basis for the design, optimization, and mobility studies of small wheeled mobile platforms in forest.

Populus spp., as an economic forest, ecological protection forest and national reserve forest construction species, plays a pivotal role as a significant carbon sink in achieving the goal of “carbon peaking and carbon neutrality” due to their fast-growing and wide-adaptable characteristics. However, the productivity of poplar plantations has been seriously affected by foliage-feeding and wood-boring insect pests. Therefore, it is an urgent task to elucidate the molecular mechanism of insect resistance in poplar and cultivate new insect-resistant and high-yielding poplar varieties for the development of poplar plantations. In this paper, we firstly outline the progress of molecular mechanism of poplars in reducing biotic stress through forming leaf trichomes, fortifying physical defenses including increased wood density, and rapid responses of secondary metabolites such as intrinsic phenolic glycosides and volatiles, as well as protease inhibitors. Then, we summarize the main applications of poplar cross-breeding, transgenic breeding technology, and multi-omics analysis in the cultivation of new varieties of poplars with insect-resistance and in the mining of key resistant sites and genes. The biosafety evaluation methods and progress of insect-resistant transgenic poplars are analyzed. Finally, it is proposed that in the future, emphasis should be placed on analyzing the molecular mechanism of poplar resistance to trunk borers, and integrating traditional cross-breeding approach with modern breeding techniques such as transgenics, gene editing and whole genome selection around the breeding goals to realize polymer breeding for insect resistance, enhanced quality, and increased yield. Concurrently, it is essential to establish and improve the biosafety assessment protocols and regulations for transgenic and gene-edited poplars for laying a solid theoretical and practical foundation for the genetic improvement and molecular design breeding of insect-resistant poplars.