Objective: This study aims to investigate the impact of elevated CO₂ concentration and temperature on the morphological characteristics and nutrient component accumulation of three Lycium barbarum cultivars, so as to provide a theoretical basis for non-wood forests to cope with climate change and breed excellent adaptive cultivars. Methods: Three L. barbarum cultivars (‘Ningqi 1’, ‘Ningqi 7’, ‘Ningqi 10’) were subjected to the elevated CO₂ concentration (eCO₂) and atmospheric temperature (eT) in an Open-Top Chamber (OTCs) simulation control system. Fruits were collected at the young fruit stage (YF, treated for 60 days), green fruit stage (GF, treated for 70 days), coloring fruit stage (CF, treated for 80 days), and red fruit stage (RF, treated for 90 days) for measuring morphological characteristics and nutrient composition. Result: 1) Morphological analysis indicated that elevated CO₂ concentration significantly increased the longitudinal and transverse diameters of fruits at the CF and transverse diameter of fruits and single fruit weight at the RF of ‘Ningqi 1’. The elevated CO₂ concentration significantly increased the longitudinal diameter at the GF and the transverse diameter of fruits at the CF of ‘Ningqi 7’. The elevated CO₂ concentration significantly increased the transverse diameter of fruits at the YF and the single fruit weight at the CF of ‘Ningqi 10’. Elevated atmospheric temperature significantly increased the longitudinal diameter of fruits at the CF and RF, as well as the single fruit weight at the RF of ‘Ningqi 1’. Elevated atmospheric temperature significantly increased the longitudinal diameter of fruits at the GF and CF, as well as the transverse diameter of fruits and single fruit weight at the CF and RF of ‘Ningqi 7’. Elevated atmospheric temperature significantly increased the single fruit weight of ‘Ningqi 10’ (P<0.05). 2) Nutrient component analysis revealed that elevated CO₂ concentration increased the levels of galactose, sucrose, betaine, and flavonoids in the fruits of ‘Ningqi 1’ at four developmental stages, increased the levels of fructose, total sugar, sucrose, polysaccharides, carotenoids, and betaine at the RF of ‘Ningqi 7’, and increased the levels of galactose, fructose, glucose, and polysaccharides at the RF of ‘Ningqi 10’ (P<0.05). Elevated temperature treatment significantly increased the levels of galactose, fructose, total sugar, polysaccharides, betaine, and flavonoids at the RF of ‘Ningqi 1’, increased the levels of galactose, glucose, sucrose, and fructose at four developmental stages, as well as the levels of fructose, total sugar, polysaccharides, carotenoids, and betaine at the RF of ‘Ningqi 7’, and increased the levels of sucrose, carotenoids, and flavonoids at four developmental stages, as well as the levels of galactose, total sugar, and betaine at the RF of ‘Ningqi 10’ (P<0.05). Conclusion: Elevated CO₂ concentration and atmospheric temperature promote the morphological development and nutrient accumulation of L. barbarum. Among the three cultivars, ‘Ningqi 10’ exhibits stronger adaptability, with the largest increase in fruit size, single fruit weight, and 100-seeds weight during the development stage. Additionally, significantly increased levels of galactose, fructose, total sugar, polysaccharides, carotenoids, and betaine in the fruits.

Objective: This study aims to explore the effect of elevated CO₂ concentration on carbohydrate accumulation during the development of Lycium barbarum fruits,so as to provide a reference for adaptive management of L. barbarum to cope with climate change. Method: L. barbarum ‘Ningqi 1’ was used as the experimental material. An open-top chamber simulation control system was applied to elevate the CO₂ concentration (800±20 μmol·mol^?1), with the ambient CO₂ concentration (400±20 μmol·mol^?1) served as the control. After 60 days of treatment, the root, stem, leaf, and fruit samples were collected respectively at the young fruit stage, green fruit stage, coloring fruit stage, and red fruit stage, and the content of their sugar components, sugar metabolism-related enzyme activity, and relevant gene expression were determined. Result: 1) The elevated CO₂ concentration promoted the accumulation of lactose, sucrose, and total sugars during the fruit development, and at the red fruit stage, the content of lactose, fructose, sucrose, and total sugars significantly increased by 35.71%, 23.18%, 19.57%, and 12.23%, respectively, compared to the control group (P<0.05). 2) Furthermore, elevated CO₂ concentrations significantly (P<0.05) increased the activity of malic acid synthase (LbMS), neutral conversion enzyme (LbAI), sucrose phosphate synthase (LbSPS), and sucrose synthase (LbSS) in the root, stem, leaf, and fruit tissues of ‘Ningqi 1’ during its development. The activity of α-galactosidase (LbGALA) increased from leaf to fruit. Under the elevated CO₂ concentration treatment, the activity of the α-galactosidase in the fruits at four different stages was significantly increased by 19.54%, 36.68%, 21.00%, and 24.93%, respectively, compared to the control group (P<0.05). The activity of sucrose synthase and sucrose phosphate synthase in leaves was significantly higher than that in the other tissues (P<0.05). The gene expressions of LbGALA and LbNI were significantly up-regulated at the mature fruit stage (P<0.05). 3) The elevated CO₂ concentrations significantly up-regulated the gene expressions of LbGAE, LbNI, and LbSPS in stems, LbGALA in fruits, and LbMS and LbAI in roots. The expression levels of LbSPS and LbSS were significantly up-regulated in leaves (P<0.05). Conclusion: The elevated CO₂ concentration promotes the expression of sugar metabolism-related genes in different tissues of L. barbarum, and it also increases enzyme activity, and thereby promoting the accumulation of lactose, sucrose, and total sugars in the fruit.

Objective: This study aims to investigate the differences in wax content and composition in pericarp at various picking periods, and explore the relationship between meteorological factors and wax accumulation in pericarp of Lycium barbarum during different picking periods, in order to provide a theoretical basis for the selection of suitable drying methods for different picking periods. Method: The fruits of L. barbarum ‘Ningqi No. 1’ and L. barbarum ‘Ningqi No. 5’ in three picking periods (old eye branch period, seven-inch branch period and autumn fruit period) were used as materials. GC-MS technology was used to measure and analyze the wax content and components. The meteorological factors in different picking periods were monitored by JL-18 air temperature, humidity and light recorder. The relationship between wax content and components in pericarp and meteorological factors was analyzed by regression analysis. Result: 1)There were significant differences in fruit wax content between the two L. barbarum varieties during the three picking periods of green fruit stage, color change stage and red fruit stage. The wax content of the fruit at the red fruit stage was significantly different from that at the green fruit stage and color change stage. However, the difference in wax content between green stage fruit stage and color change stage was not significant. 2) The wax composition analysis showed that the wax of ‘Ningqi No.1’ peel was mainly composed of hexacosane, octacosane, 1-iodoctacosane, 1-iodotriacontane, docosanol and β-amyrin, while the wax of ‘Ningqi No. 5’ peel was mainly composed of hexacosane, heptacosane, 1-iodoctacosane, 1-iodotriacontane, docosanol and 2-hexyl-1-decanol. 3) During the old eye branch period, the peel wax content of the two cultivars was significantly negatively correlated with light intensity, with correlation coefficients of ?0.759 (P<0.05) and ?0.838 (P<0.01). For ‘Ningqi No.1’, esters were significantly negatively correlated with daily average temperature, with a correlation coefficient of ?0.712. For ‘Ningqi No.5’, acids and esters were significantly positively correlated with daily average humidity, with correlation coefficients of 0.728 (P<0.05) and 0.739 (P<0.05), ketones were significantly positively correlated with night average temperature, and significantly negatively correlated with light intensity, with correlation coefficients of 0.717 (P<0.01) and -0.649 (P<0.05), alkanes were significantly negatively correlated with daily average humidity and night average temperature, with correlation coefficients of ?0.772 (P<0.01) and 0.637 (P<0.05), iodinated alkanes were significantly positively correlated with night average humidity, with the correlation coefficient of 0.820 (P<0.01). During the seven-inch branch period, for ‘Ningqi No.1’, the alkanes were significantly positively correlated with the average night temperature, with the correlation coefficient of 0.779 (P<0.05), the iodinated alkanes were significantly negatively correlated with the average daily temperature, with the correlation coefficient of -0.724 (P<0.05), the acids were significantly negatively correlated with the average daily humidity, with the correlation coefficient of -0.680. For ‘Ningqi No.5’, the wax content was significantly positively correlated with night average humidity and light intensity, with the correlation coefficients of 0.795 (P<0.01) and 0.748 (P<0.01), the ketones and iodoalkanes were significantly negatively correlated with daily average temperature, with the correlation coefficients of -0.887 (P<0.01) and -0.749. During the autumn fruit period, for ‘Ningqi No.1’, the alkanes and iodoalkanes were significantly positively correlated with night average temperature, with correlation coefficients of 0.887 (P<0.01) and 0.767 (P<0.05). Conclusion: The meteorological factors during different picking periods have differents effects on wax content and components. Temperature is mainly related to the accumulation of iodoalkanes, ketones and alkanes. Humidity is related to the accumulation of esters, acids and alkanes. Light intensity is related to the accumulation of esters and alcohols. The results provide a theoretical basis for the suitable dewaxing agent pretreatment in the drying of L. barbarum fruits at different picking periods.

Objective: Drying is an important step of the processing of Chinese medicine wolfberry. The effects of different varieties (lines) of Lycium barbarum fruit traits and pretreatment on drying were studied to provide a valuable theoretical basis for the drying process of L. barbarum. Method: In this study, different varieties (lines) of L. barbarum with obvious differences in dryness were used as experimental materials. The paraffin sectioning and scanning electron microscopy techniques were used to investigate the fruit processing characteristics, peel and cuticle structure, and peel waxy micromorphology, as well as effects of different pretreatment times on the drying of L. barbarum fruits, by which the influence of the L. barbarum fruit traits on the drying of the fruits was clarified. Result: 1) There were significant differences in the longitudinal diameter, fresh weight of 100 grains, and single fruit volume among different varieties (lines). L. barbarum ‘16-23-7-8’ had the largest transverse diameter, longitudinal diameter, fresh weight of 100 grains, and single fruit volume, while those parameters of L. barbarum ‘Ningqi No.1’ were the lowest. 2) With the development of the fruit, the thickness of the pericarp and cuticle increased gradually and there were significant differences in those traits among different varieties (lines). The pericarp thickness of L. barbarum ‘Ningqi No.5’ was the largest with 768.273 μm, and that of L. barbarum ‘Ningqi No.1’ was the lowest with 445.100 μm. L. barbarum ‘14-402’ had the thickest cuticle with 9.420 μm, and the L. barbarum ‘16-23-7-8’ cuticle was the lowest, being 7.528 μm. 3) The epidermis of L. barbarum fruit at mature stage was covered by fascicular waxy layer, and the waxy crystals were irregular flakes, and the flake waxy layer was thicker and arranged closely. 4) There were differences in the drying time of different varieties (lines) of L. barbarum fruits, and the order from easy to difficult was ‘Ningqi No.1’, ‘Z44’, ‘16-23-7-8’, ‘14-402’, and ‘Ningqi No 5’. Compared with the control, the average drying time was shortened by 4.10 h after alkali treatment, and the average drying time was shortened by 16.94 h after chloroform treatment. Conclusion: The structure of L. barbarum peel affects the drying process of the wolfberry fruits by affecting the water transport pathway. Pretreatment can destroy the waxy layer of wolfberry epidermis and shorten the drying time. In this study, ‘Ningqi No.5’ is hard to dry, while ‘Ningqi No.1’ is the easiest to dry. Therefore, when drying wolfberry, the pretreatment method applied must take into account the differences in tissue and morphological anatomical characteristics among varieties.

Objective: To study the trend of radial growth change, response to climatic factors and ecological resilience to drought stress of Picea schrenkiana at different altitudes in the central Tianshan Mountains, and to provide theoretical references for predicting the community development trend of P. schrenkiana forests along the altitudinal gradient in the Tianshan Mountains under climate change. Method: The core samples of P. schrenkiana were collected at the lower, middle and upper forest line of P. schrenkiana forest in the middle section of the northern slope of Tianshan Mountains. Three tree-ring standard chronologies were established, and the basal area increment was calculated. The relationship between the radial growth of P. schrenkiana and climatic factors was analyzed. The resistance, recovery and resilience were used to analyze the response of P. schrenkiana to drought. Result: In the past 61 years, the radial growth of P. schrenkiana at all altitudes in the study area was significantly inhibited. The degree of inhibition was the highest at the lower forest line, followed by the middle forest belt, and the upper forest line was lighter. There are differences in the main climatic factors affecting the radial growth of P. schrenkiana at different altitudes. The radial growth of P. schrenkiana at the lower forest line is mainly negatively correlated with the temperature from April to July of the current year, and is significantly positively correlated with the precipitation in June of the previous year（P<0.05）, April and June of the current year, and the self-calibrated Palmer drought index (scPDSI) from August to September of the current year（P<0.05）. The radial growth of P. schrenkiana at the middle forest belt is mainly negatively correlated with the temperature from June to August of the previous year, from March to April and June to July of the current year（P<0.05）. The radial growth of P. schrenkiana at the upper forest line is mainly positively correlated with the temperature from February to July of the current year, and is significantly positively correlated with August of the previous year（P<0.05）. There was a significant positive correlation between the precipitation in April and scPDSI from June of last year to May of this year（P<0.05）. The response of radial growth of P. schrenkiana to climatic factors was different in altitudinal gradient and temporal gradient. The negative correlation with air temperature decreased successively and the positive correlation with precipitation and scPDSI decreased successively from underline to overline. The correlation with air temperature decreased gradually and the positive correlation with precipitation and scPDSI increased gradually in temporal gradient. The ecological resilience of P. schrenkiana to drought at different altitudes is different. The resistance and resilience are shown as upper forest line > middle forest belt > lower forest line, and the recovery is shown as lower forest line > middle forest belt > upper forest line. P. schrenkiana is more sensitive to drought, and its growth decreases significantly under drought stress. When the reverse balance between resistance and resilience is not broken, P. schrenkiana is not affected by the residual effect of drought. Conclusion: Due to the rapid increase of temperature and slow increase of precipitation in the study area, P. schrenkiana at different altitudes is more and more seriously affected by drought stress. Among them, the radial growth of P. schrenkiana in the lower forest line decreased the most, the resistance was the smallest, and the risk of growth decline was the highest.

Objective: By examining the relationship between the stand productivity and community structure , and analyze the factors affecting stand productivity in different forest layers of a broad-leaved Korean pine (Pinus koraiensis) mixed forest community in Changbai Mountain, the purpose of this study is to build a scientific foundation for the restoration and sustainable management of temperate forests. Method: Using vegetation survey data from a 40 hm² fixed monitoring sample plots of broad-leaved Korean pine forest in Changbai Mountain Nature Reserve in 2014 and 2019, we selected woody plants with diameter at breast height (DBH) ≥ 5 cm from the sample plot as the object. The stand was divided into four layers, namely the dominant layer, the subdominant layer, the medium layer and the pressed layer, using the interval of 10 cm breast diameter. We used the Pearson correlation to analyze the relationship among species diversity, stand density, structure diversity , and productivity factors; a structural equation model using productivity as the response variable was developed to investigate the effects of species diversity, structural diversity and stand density on productivity. Result: 1) There was a significantly positive correlation between stand density and productivity (P<0.05), and it declined as the rise of forest layers. 2) The analysis of the Pearson correlation shows that the species of Shannon-Wiener index is significantly positive (P<0.05), and the correlation of the correlation of the forest rising has weakened. Conversely, there is a significant negative (P<0.05) correlation between the Sorensen index that represents β diversity, but this correlation is not significant in the medium wood layer and the Asian advantage wood layer. In addition, the species Pielou index and productivity are significantly negative (P<0.05). And the correlation coefficients increase with the rise of the forest and decrease; DBH Gini index and DBH Pielou are significantly negative with productivity, and this correlation weakens with the upper forest layer, and has no significant correlation with the productivity in the superior wood layer. The DBH Shannon-Wiener index is significantly positively (P<0.05) correlated with productivity, and the correlation between the upper forest movement is reduced, and the correlation coefficient is reduced from 0.44 to 0.31. 3) In different forest layers, he stand density had a significant impact on productivity (P<0.001), and its action intensity gradually decreased with the rise of forest layers, and the path coefficient dropped from 0.59 to 0.27. Species diversity had a significant positive (P<0.05) effect on productivity in the pressed and medium layers, but had no effect on productivity in the dominant and subdominant layers; structural diversity indirectly affected stand productivity in the pressed and medium wood layers by acting on species diversity and stand density, and directly affected stand productivity in the dominant and subdominant wood layers. Conclusion: To summarize, the study shows that stand density had a significant effect on productivity in each forest layer (P<0.05), and the intensity of action gradually decreased as the forest layer increased. The direction and intensity of the influence of species diversity and community structure on productivity differ across forest layers. Therefore, in the practice of forest production and management of forest resources, the relationship between forest structural characteristics at different vertical spatial scales of forest layers and forest productivity should be fully considered.

objective: Soil organic carbon contents were simulated for typical forests (evergreen coniferous, deciduous broadleaved and evergreen broadleaved forests) in central China. The optimal models were used to reveal the key factors influencing the accumulation and spatial distribution of soil organic carbon in mixed forests in central China, which would technically improve the understanding of spatial pattern of forest soil carbon. Method: Forest soil organic carbon content of 0–60 cm was modeled by four advanced machine learning algorithms, including support vector machine, multi-layer perceptron of artificial neural networks, random forests and quantile regression forests. Model selection was conducted by comparing their model explanation and performance stability. Result: Models for organic carbon content of forest soil were developed successfully using all the 4 algorithms for 0–60 cm soil depths. The results of multi-layer perceptron, random forests, and quantile regression forests were significantly better than support vector machine, among which random forests processed the most stable results along soil layers, with the highest R² at 0.620. Parent material, bulk density, soil porosity, topography, elevation, vegetation, and moisture deficit conditions jointly influenced the soil organic carbon content of 0–60 cm in the mentioned forests, while the significant factors differed among the topsoil (0–20 cm), middle (20–40 cm) and deep soil layers (40–60 cm) due to different mechanisms. Forest soil organic carbon content in the topsoil was comprehensively affected by soil porosity, geographic factors, vegetation, and climate, besides soil density as the most significant covariate (P<0.05). In the middle soil layer, soil properties and topography were still significant, while the influence of each factor on the soil organic carbon content showed complexity and transitional characteristics (P<0.05). In the deep soil layer, the parent material was the most important influencing factor, followed by soil properties and moisture insufficiency, while the influence of vegetation decreased (P<0.05). Geographically, the 0–20 cm surface soil organic carbon was higher in the southeast than in the northwest, while contents were observed higher in the west than in the east for the two deeper soil layers. Forest soil organic carbon contents were higher in mountainous forests with lower latitudes and higher elevations. Strong evaporation or insufficient moisture supply would limit the accumulation of forest soil organic carbon in all soil layers. Forest soil organic carbon content decreased significantly along soil layers. The highest soil organic carbon contents were found in evergreen coniferous forests, followed by deciduous broadleaved and evergreen broadleaved forests. Conclusion: The distribution of soil organic carbon in natural forests is characterized by spatial heterogeneity and differences among forest compositions in central China. Evergreen coniferous forests performed the largest contribution to soil organic carbon among these forests. Parent material and soil physical properties played a decisive role in the enrichment and distribution of soil organic carbon in the regional forests. Both suitable geographical and favorable topographical conditions contributed to the enrichment of soil organic carbon in forests. The proportion of mixed forests with local species could be promoted in forest management and silviculture to enhance forest soil carbon sinks.

Objective: This study aims to explore the effects of planting Pinus elliottii, Cunninghamia lanceolata and Alnus cremastogyne on the soil heavy metal mass fraction and microbial community composition in the iron tailing mine area of Jiulong, and to provide reliable scientific data and theoretical basis for vegetation restoration in this mine area and areas with similar stand conditions. Method: Rhizosphere and non-rhizosphere soil samples and root, stem and leaf samples of Pinus elliottii, Cunninghamia lanceolata and Alnus cremastogyne were treated by microwave digestion. The heavy metal mass fractions of the samples were determined by ICP and AAS. Macrogenomics sequencing was used to analyze the rhizosphere and non-rhizosphere soil samples of the three tree species and to investigate the composition of microbial communities in the corresponding soils of the three tree species. Result: 1) The biotransfer coefficients of all three species were greater than 1 for Hg, Cu, Pb, and Zn, and less than 1 for Cr, indicating their strong transfer ability to Hg, Cu, Pb, and Zn and weak transfer ability to Cr. The biotransfer coefficients of Cunninghamia lanceolata to As were greater than 1, indicating that the transfer ability of Cunninghamia lanceolata to As was strong. 2) The bioenrichment coefficients of Cunninghamia lanceolata for Hg and Pb were all greater than 1, indicating that Cunninghamia lanceolata has good bioenrichment ability for Hg and Pb. Compared with other heavy metals, Pinus elliottii had the highest bioenrichment coefficients for Hg and Pb, and Alnus cremastogyne had the highest bioenrichment coefficients for Zn, indicating that Pinus elliottii had better bioenrichment ability for Hg and Pb, and Alnus cremastogyne had better bioenrichment ability for Zn. 3)At the phylum level, the phylum with the highest relative abundance in J1 was Acidobacteria (45.55%), followed by Proteobacteria (12.11%). The most abundant phylum in J2, J3, J4, J5, and J6 was Proteobacteria, with an abundance range of 22.72% to 44.56%. The next most abundant phylum was Acidobacteria, with an abundance range of 13.49% to 16.56%. At the genus level, the dominant genera in J1 were Bradyrhizobium and Ktedonobacter spp. The dominant genera with the highest relative abundance percentages in J2, J3, J4, J5 and J6 were Bradyrhizobium and Sphingomonas spp. Conclusion: 1) Pinus elliottii, Cunninghamia lanceolata and Alnus cremastogyne all had a strong transfer ability for Hg, Cu, Pb and Zn, and all had a weak transfer ability for Cr. The transfer ability of Cunninghamia lanceolata to As was stronger. Pinus elliottii and Cunninghamia lanceolata have better bioenrichment ability for Hg and Pb, and Alnus cremastogyne has better bioenrichment ability for Zn. Pinus elliottii and Cunninghamia lanceolata can be used as pioneer trees for Hg and Pb restoration, and Alnus cremastogyne can be used as restoration trees for Zn with their intercropping. 2) Based on the analysis at the two taxonomic levels of phylum and genus, the dominant microbial communities in the rhizosphere and non-rhizosphere soils of the three tree species were all in the phylum Proteobacteria, and the planting of all three tree species promoted the increase in the relative abundance of microorganisms of the phylum Proteobacteria in soil. Phylum Proteobacteria can improve the absorption of heavy metals by plants and promote plant growth. The two complement each other and promote each other. It can effectively improve the absorption efficiency of heavy metals by plants.

Objective: This paper proposed an individual tree segmentation algorithm utilizing hierarchical layer stacking approach to optimize the use of high-density LiDAR point cloud data, thereby improving the accuracy of individual tree segmentation in the understory of forest stands. Method: Diverging from traditional algorithms which utilize canopy vertices as cluster seeds, this hierarchical overlay-based segmentation algorithm selects local maxima of each layer after horizontal slicing of point clouds for tiered clustering. It diminishes the over-segmentation due to branches through layered overlay and iterative refinement, securing segmentation precision of canopy trees and boosting extraction of understory trees. Result: The tree segmentation algorithm based on layer stacking exhibits high precision in larch stands of various stem densities, with a maximum matching success rate of 94% between extracted and observed trees, and up to 92% in medium to high density stands. Compared to other algorithms, the matching rate for mid and lower-layer trees can be improved by 20% to 40%. In terms of individual tree height extraction precision, the correlation coefficient between extracted and observed tree heights is 0.8, with a relative root mean square error of 8.45%. The highest correlation coefficient between extracted and observed crown widths is 0.83, with a relative root mean square error of 16.5%. Conclusion: By stacking hierarchical clustering and optimizing seed point selection, the comprehensive use of point cloud data across forest layers enhances individual tree segmentation accuracy, providing valuable data support for forest management and operations.

Objective: Under the background of obvious shifts in the amount and component of global radiation, this study aims to elucidate the impact of variations in the fraction of diffuse radiation (F_dif) on energy partitioning of a poplar plantation in the North China Plain. Method: The eddy covariance techniques and microclimate observations were used to investigate energy fluxes and environmental variables in a poplar plantation during the growing seasons of 2019 and 2021 (DOY 91–304). Result: The energy distribution of the ecosystem primarily consisted of latent heat flux (LE) during the mid-growing season (DOY 152–243), whereas of sensible heat flux (H) during early (DOY 91–151) and late (DOY 244–304) growing seasons. There was a significant negative correlation between F_dif and Bowen ratio (β), and a significant positive correlation between F_dif and G_s, Ω, and α. Path analysis revealed that G_s was the crucial factor regulating the ecosystem's energy distribution. When F_dif decreased, G_s decreased, saturated water vapor pressure difference (VPD) increased, and the ecosystem’s β significantly increased, which in turn altered ecosystem energy partition patterns. Conclusion: The change of F_dif will affect the energy distribution of the poplar plantation ecosystem in the North China Plain. A decrease in F_dif results in a higher proportion of LE and a lower proportion of H, significantly affecting energy partitioning in poplar plantation ecosystems. In the context of climate change, this study not only provides a deep insight into the energy allocation mechanisms of poplar plantation ecosystems in the North China Plain, but also plays a crucial role in accurately assessing the ecological service functions of these forests.

Objective: This study aims to explore the relationship between different leaf colors of Acer truncatum and the content and distribution of internal pigments, as well as the ultrastructure of mesophyll cells, to provide cytological basis for clarifying the internal mechanism of leaf coloration of A. truncatum, and provide a reference for revealing the color changing mechanism of red leaf plants. Method: A. truncatum leaves were divided into three categories of green, red and yellow leaves according to the leaf color. The contents of chlorophyll, carotenoid and anthocyanin in the leaves with different colors were determined, and the distribution of pigments in various tissues of the leaves was observed. According to the process of leaf color change, it was able to be divided into six categories: light green, green, yellow, reddish tip, full red and brown tip. The chloroplasts and other organelles of mesophyll cells were observed by using a transmission electron microscopy. Result: There were significant differences in pigment content and distribution, and ultrastructure among leaves with different colors. 1) The anthocyanin content of red leaves was significantly higher than that of yellow and green leaves (P<0.05), while the chlorophyll content was lower. The chlorophyll content of yellow leaves was the lowest, the carotenoid content was significantly (P<0.05) higher than that of red leaves, and the ratio of carotenoid to chlorophyll was significantly higher than that of green leaves and red leaves (P<0.05). The chlorophyll and carotenoid contents of green leaves were significantly higher than those of yellow and red leaves (P<0.05), and the anthocyanin content was significantly lower than that of red leaves (P<0.05), but there was no significant difference in anthocyanin content between green and yellow leaves. Correlation analysis showed that the ratio of pigment content in A. truncatum leaves was negatively correlated with chlorophyll content. 2） There were no pigments in the upper and lower epidermic cells. Anthocyanin was mainly distributed in the palisade tissue. The anthocyanin distribution was prominent in red leaves and less in green leaves and yellow leaves. The distribution of carotenoids was prominent in the yellow leaves. Anthocyanin in yellow leaves was also distributed in spongy tissue. 3） Chloroplasts in young green leaves were still developing, and those in green leaves were mature and had starch grains. After the leaves turned red, the ribosomes in the chloroplasts reduced, and residues of the chloroplast disassembly appeared in fully red leaves. Chloroplasts were damaged in the yellow leaves, and there were osmiophilic granules in the cells. There were lots of osmiophilic granules in tip-brown leaves, and some cells were hollow. Conclusion: There is no structural variation in the coloration of A. truncatum leaves. The color change is caused by the decrease of chlorophyll and carotenoid content during the reddening process of leaves, especially a rapid decrease in chlorophyll content. At the same time, the anthocyanin content increases, and the ratio of anthocyanin to chlorophyll and carotenoid increases. Anthocyanins in the leaves are mainly distributed in the palisade tissue, and synthetized before leaf coloration. With the increase of the anthocyanin content, leaves eventually exhibit color. In the process of leaf coloration, the chloroplasts gradually disintegrate, and some senescence features occur. The colored leaves in A. trumcatum are senescent colored leaves. Yellow leaves are in poor nutritional condition, and their color changes from green to yellow, and cannot turn red. Yellow leaves age faster than red leaves.

Objective: To improve the detection accuracy of wildlife in complex forest environments and advance the development of forest wildlife conservation technology, an improved detection algorithm based on the YOLOv5s network model is proposed for forest wildlife images taken by trap cameras in this study. Method: A dataset containing several typical forest wildlife in the Huping Mountain National Nature Reserve in Hunan was used as the research object. Firstly, image enhancement was performed by cropping, normalizing and scaling the ground truth box images, and then two to four cropped images were randomly collaged to form new dataset elements to enrich and enhance the dataset image information. Secondly, a weighted channel stitching method based on the idea of channel attention was used, specifically, the number of channels was changed by introducing weights in channel stitching, and the weights was continuously updated to increase the number of channel layers with important feature information by a back-propagation training method. Then, the Swin Transformer module was introduced to and combined with the CNN network to add a self-attentive mechanism to the convolutional neural network feature extraction, which integrated the advantages of the feature extraction layers of both networks and improved the perceptual field of feature extraction. Finally, a better α-DIoU loss function was chosen to replace the GIoU loss function, and a new geometric factor penalty term was introduced to address the loss caused by the overlapping area of the bounding box and the distance of the centroid. Result: Under the same experimental conditions with the same data set, compared with the original YOLOv5s network model, the improved algorithm greatly improved the average accuracy and average regression rate of detection, increased the mean average precision (mAP) from 74.1% to 88.4%, obtained an accuracy improvement of 14.3%, and also outperformed other popular target detection algorithms such as YOLOv3, YOLOXs, RetinaNet and Faster R-CNN. Conclusion: The low contrast between background and target of forest wildlife images taken by trap cameras and serious overlap of occlusion result in high detection false detection rate and leakage rate. To address those problems, in this study a series of improvement measures have been proposed in the detection algorithm, which provides a new feasible solution and idea for the protection and data acquisition of forest wildlife in China.

Objective: In order to provide theoretical reference for better controlling the sanding surface roughness of the wood board with air-drum belt sanding, the effect of sanding parameters on grinding force and the relationship between grinding force and sanding surface roughness were studied. Method: The main research contents included: we carried out the single factor tests on the air-drum belt sanding MDF (medium-density fiberboard), established the finite element model of the air-drum belt sanding MDF, based on fluid cavity theory. By combining the finite element model with the single factor tests, we investigated the influence of air drum pressure, feed rate and axis parallelism error on the sanding force and the sanding surface roughness, and analyzed the relationship between sanding force and surface roughness. Result: With the increase of air drum pressure, feed rate and axial parallelism error, the sanding force of the specimen increased, but the reasons for the increase of the sanding force were different. The normal stress at the contact center of the specimen was mainly related to the air pressure of the air drum. Corresponding to the measuring point in the middle area (6-59 mm), the local sanding force of the specimen in the air drum pressure group and the feed group were approximately equal, and the local sanding force of the measuring point was approximately linearly related to the position during contact of the specimen in the axial parallelism error group. The air pressure of the air drum had little effect on the sanding force and surface roughness of the specimen, while the feed rate can significantly improve the surface roughness of the specimen. The linear fitting correlation coefficient R² between the surface roughness of the specimen and the local sanding force was 0.975, the linear fitting correlation coefficient R² with the total sanding force was 0.871, and the linear correlation coefficient between the surface roughness and the local sanding force is better. Conclusion: The finite element model of the air-drum belt-sanded MDF can accurately predict the sanding force of specimen. When analyzing the relationship between the grinding force and the surface roughness of specimen, choosing the local grinding force of specimen is better than the total grinding force and the normal stress of specimen.

Roadcut slopes are artificially created habitats constantly affected by human disturbance. The revegetation of these slopes has long challenged forestry managers due to the dual constraints of seed availability and harsh conditions. Despite advancements in slope revegetation techniques, resulting plant communities often lack naturalness and sustainability. A key reason for this lies in the oversight of current restoration techniques, neglecting the formation patterns and potential roles of plant traits in the community assembly process. Functional trait analysis of plants is now a fundamental tool for understanding ecological processes and patterns in plant communities. However, the significance of seed functional traits, particularly those closely tied to community assembly processes like seed dispersal, deposition, and germination, is frequently underestimated. To enhance our understanding of the role of seed traits in community assembly, this paper reviews existing research based on the biotic and abiotic characteristics of roadside slope environments and their associated ecological constraints. The analysis identifies key factors influencing plant colonization on roadcut slopes under natural conditions from a trait perspective. Additionally, the paper outlines the potential of seed traits in predicting community assembly and selecting suitable restoration plants. In general, seed traits related to dispersal, persistence, and germination play a crucial role in the successful colonization of plants on roadcut slopes. During the early stages of succession, source scarcity and harsh abiotic environments emerge as primary factors influencing the establishment of plant communities on slopes. Plants adapted to slope environments often employ unique ecological strategies in seed dispersal, deposition, and germination to cope with erosive runoff, arid conditions, and infertile environments. Summarizing these findings contributes to a deeper understanding of the assembly processes and patterns of early plant communities on roadcut slopes from the perspective of seed traits. This sheds light on the significant role and potential of seed traits in this process, providing theoretical support for research and practices in the revegetation of roadcut slopes, especially in sensitive areas.

Saccharides are the basic nutrients and important components for living organisms, while sugar based platform compounds are essential chemicals derived from sugars through biological or chemical transformation and can be further transformed into high-value bio-based chemicals or materials. Bamboo, which has a large biomass resource and short growth cycle, is a potential source for development of a series of biomass-based sugar platform compounds. The process of preparing monosaccharides from bamboo by enzymatic hydrolysis is green and sustainable, where the most critical step is pretreatment, which requires reasonable cost, easy and environmentally friendly spent liquid treatment process and effective utilization of lignin. This paper reviews the influence of pretreatment methods on enzymatic hydrolysis for the preparation of monosaccharides from bamboo in the last decade, and summarizes the advantages and shortcomings of pretreatment methods including physical, chemical, physicochemical, eutectic solvent, organic solvent and other methods, compares the perspectives of each reaction mechanism, substrate yield, cellulose content in substrate, enzymatic hydrolysis efficiency and sugar degradation to generate fermentation inhibitors. To reach the goal of green and efficient conversion utilization, the pretreatment process, enzymes, bamboo species and age, lignin utilization should be taken into account. The future research of bamboo biorefinery technology are proposed: 1) due to the hardness of bamboo materials, it is necessary to explore low energy consumption crushing method; 2) to develop pretreatment process which not only has green chemicals, simple process, low degradation byproduct, but also adaptive the specific structural characteristics of bamboo; 3) research on techniques for high-value utilization of bamboo lignin, and promote the utilization of the whole chemical components of bamboo raw materials.

Cellulose is deemed as the most abundant and renewable resource on the earth. Enzymatic saccharification of cellulose to glucose is an ideal bioconversion, but its low efficiency significantly impedes the development of cellulose industrialization. Recognition and deconstruction of different recalcitrant factors and improving enzymatic hydrolysis efficiency are still the vital scientific problems in the high valorization of cellulose. In this article, various recalcitrant factors that impeding the enzymatic hydrolysis were summarized at multidimensional levels, in the aspects of macrostructure, microstructure, ultra-structure, molecule, chemical group, chemical element, chemical bonds and gene. Furthermore, we revealed that recalcitrant factors exhibited typical heterogeneity in specific biomass, high dynamics in different development stage of plant, and complex relation during the pretreatment. Finally, several novel research directions and strategy on recalcitrant barrier were proposed: cell wall interface recalcitrance, modification and valorization of cell wall from a biorefinery concept and saccharification hydrolysis with synergies of multiple enzymes.