Objective: This paper aims to explore the effect of thinning disturbance on the productivity stability of stand productivity in a secondary natural mixed conifer-broadleaved forest in Jiaohe in Jilin province, in order to provide a theoretical basis for the sustainable management of mixed carboniferous forest. Method: Four sample plots with an area of 1 hm² were established in the mixed forest in July 2011, thinning was conducted in December 2011 with a thinning intensity ranged from 2.7% to 77.6% with an average of 39.2%. The retained trees were measured in 2013, 2015 and 2018. using the data of woody plants obtained from 100 consecutive sample plots, the correlations of the thinning intensity, stand density, soil nutrient, tree size differentiation (DBH Shannon-Wiener index), species diversity (Species Simpson index) and the productivity stability were analyzed by using a linear regression model. Analysis of variance components was used to compare the contributions of different variables to the productivity stability. Furthermore, the effects of thinning on the tree size differentiation, the species diversity and the productivity stability and their inter-relations were analyzed by using structural equation model. Result: There was no significant correlation of the thinning intensity with the productivity stability, but a significant positive correlation of the species diversity and the tree size differentiation with the productivity stability (P < 0.05). The stand density had a significant negative impact on the productivity stability (P < 0.05). Among the variance components, that of species diversity alone contributed 19.5% of the productivity stability, those of the stand density and the tree size differentiation contributed to the productivity stability by 7.0% and 7.6% respectively. The thinning intensity had a significant negative effect on the stand density, the soil nutrients (the first principal component of soil carbon, nitrogen, phosphorus and calcium content) and the tree size differentiation (P < 0.001), and the path coefficients were －0.629, －0.316, and－0.255 respectively, but had no significant effect on the species diversity and the productivity stability. The stand density, the species diversity, and the tree size differentiation had significant effects on the productivity stability (P < 0.05), and the path coefficients were －2.063, 1.652 and 1.463 respectively. The stand and the tree size differentiation had significant negative effects on the productivity stability (P < 0.05), path coefficients were －2.365 and －0.556, and the species diversity had a significant positive effects on the productivity stability (P < 0.05), with a path coefficient of 1.652; the soil nutrients had no significant effects on the productivity stability; The thinning intensity had no significant direct impact on the productivity stability, neither indirect impact on the productivity stability through the species diversity and soil nutrients, but had significant indirect impact mainly through the stand density and the tree size differentiation. The thinning intensity has a significant negative effect on the productivity stability (P < 0.05), with a path coefficient of -0.290. Conclusion: The thinning intensity has no direct impact on the productivity stability. The stand density, the tree size differentiation and the species diversity have direct impact on the productivity stability. The thinning intensity indirectly influences the productivity stability through adjusting the stand density and the tree size differentiation, and further influences the variation of forest productivity. Therefore in forest management, a reasonable thinning interference is of great importance for promoting the stability of forest productivity.

Objective: This research was aimed to investigate the spatiotemporal distribution and coverage changes of forest and grass vegetation in the Yellow River Basin during 2009 and 2018, and to forecast future development trend of the forest and grass coverage in order to provide a basis for scientific protection and precise restoration of forest and grass vegetation, and for the promotion of positive ecosystem succession in the Yellow River Basin. Method: Based on the SPOT/VEGETATION NDVI time series data from 2009 to 2018, the spatial distribution and temporal changes of the vegetation coverage of forest and grass in the Yellow River Basin were studied by using annual mean method, Theil-Sen median trend analysis and Mann-Kendall test. The sustainability characteristics and future development trend of vegetation coverage were analyzed using Hurst index method. Result: In the total area of forestland and grassland in the Yellow River Basin, the area with a high vegetation coverage (NDVI≥0.7) accounted for 42.34%, distributed in aggregation in the Qilian Mountains, the east of Three-Rivers' Origin and Zoige grassland in the upper reaches of the basin, the northern foot of Qinling Mountains in the middle reaches, the south of Huhuanyong line in the Loess Plateau, and the surrounding area of Jinan City in the lower reaches; The area with a medium vegetation coverage area (0.3 < NDVI < 0.7) accounted for 44.92%, mainly distributed in the west of Three-Rrivers' Origin in the upper reaches of the basin and the junction of Ningxia, Inner Mongolia, and Shaanxi in the middle reaches. The area with a low vegetation coverage (NDVI < 0.3) accounted for 12.74%, mainly distributed in the Mu Us sandy land, the Loess Plateau in central Gansu Province, and the southern foot of Yinshan Mountains in the upper reaches of the basin. From 2009 to 2018, the annual mean NDVI of vegetation in forestland and grassland of the Yellow River Basin showed an overall increasing trend, with a growth rate of 0.007 4 a^-1. In the past 10 years, the area with improved vegetation coverage accounted for 81.62% of the total area of forest and grass, of which the area of significant improvement accounted for 33.36%. The area with vegetation degradation accounted for 13.86%, which was basically the same as the area with a low vegetation coverage. In the future, 61.89% of the vegetation coverage will develop in a positive direction, 33.60% in a negative direction, and 4.51% in a stable and uncertain direction. Conclusion: The vegetation coverage in forestland and grassland in the Yellow River Basin is high in the southeast and northwest mountain areas, and low in the north. From 2009 to 2018, the improved area is much larger than the degraded area, mainly concentrated in the Qilian mountain forest area and Zoige grassland in the upper reaches, Liupanshan forest area, Ziwuling forest area, Huanglongshan forest area, Luliang Mountain forest area and the northern foot of Qinling Mountain in the middle reaches.The degraded areas are mainly distributed in the Mu Us sandy land and the Loess Plateau in central Gansu Province with low vegetation coverage, where is the priority area for harness and restoration. The future development of vegetation coverage in the Yellow River Basin tends to be good in general. It is predicted that the positive development area is much larger than the negative development area. In the negative development area, although the vegetation coverage in Three-Rivers' Origin and Mu Us sandy land has slightly improved, the sustainability is poorer, and there is a possibility of degradation in future, therefore it should be given great attention in the ecological conservation and restoration of the Yellow River Basin.

Objective: This study is aimed to explore the distribution and main influencing factors of microbial biomass C and N across three different altitudinal vegetation zones, which provides baseline data for understanding the process of soil carbon and nitrogen cycling and its regulation mechanism in subtropical forest. Method: We used the chloroform fumigation method to measure changes in microbial biomass C and N along altitudinal gradients and soil layers in three typical vegetation zones (i.e., subtropical monsoon evergreen broad-leaved forest, sub-humid evergreen broad-leaved forest, and humid evergreen broad-leaved forest). The partial Mantel's test and Fourth-Corner method were used to analyze the relationships of microbial biomass C and N to vegetation diversities and soil properties. Result: 1) The altitudinal variation of soil microbial biomass C and N were significant (P < 0.05). Soil microbial biomass C and N in communities of the three vegetation zones increased with the rise of altitudes, in an order of subtropical monsoon evergreen broad-leaved forest (28.05, 4.95 mg·kg^-1) < semi-humid evergreen broad-leaved forest (15.75, 2.84 mg·kg^-1) < humid evergreen broad-leaved forest (41.61, 7.80 mg·kg^-1). 2) Soil microbial biomass C and N significantly decreased with the depth of soil layers (P < 0.05). Soil microbial biomass C and N were 4.26 and 3.22 times, respectively higher in 0-10 cm layer than in 40-50 cm layer. The largest range of vertical variations in biomass C and N (7.21 and 3.42 times, respectively) was observed in subtropical monsoon evergreen broad-leaved forest. 3) Partial Mantel correlation test showed that microbial biomass carbon and nitrogen had the strongest correlation with total nitrogen, soil organic matter, and pH value (P < 0.01, r≥0.75), followed by the correlation with soil moisture content, bulk density, and total potassium (P < 0.05, r>0.5). The fourth corner analysis showed highly negative correlations of soil microbial biomass C and N with the vegetation diversity (i.e., Shannon, Margalef, and Pielou index) (P < 0.01) in the subtropical monsoon evergreen broad-leaved forest, and highly negative correlation with soil pH but highly positive correlation with litter thickness, organic matter and total nitrogen (P < 0.01) in the semi-humid evergreen broad-leaved and humid evergreen broad-leaved forests in the middle vegetation zone. Conclusion: The altitudinal variation of soil microbial biomass C and N were mostly controlled by total nitrogen, soil organic matter, and soil pH, but mainly by vegetation community diversity at low altitudes, and by litter thickness, soil pH, soil organic matter, and total nitrogen at high altitudes.

Objective: In this paper, the vegetation flora, plant life forms and their responses to altitude gradients were investigated in Dunhuang and Mazongshan, to clarify the life-form characteristics of plant communities and their reflections on climatic habitats. The main purpose of this study is to provide a theoretical basis and scientific basis for the protection of regional plant diversity and vertical pattern research. Method: On the basis of plant community investigation, the life forms of vascular plants in Dunhuang and Mazongshan were counted by using Raunkiaer life form classification system, and then the life form spectrum was prepared. The life form composition of plants at different altitude gradients was analyzed. Result: 1) A total of 217 species of plants were recorded in this study area, belonging to 34 families and 122 genera, accounting for 41.46% of the total families in arid areas of China and 10.09 % of the total families in China. Among them, there were 3 species of gymnosperm belonging to 1 family and 1 genus, 175 species of dicotyledon belonging to 96 genera and 28 families, and 38 species of monocotyledon belonging to 25 genus and 5 families. 2) The life forms of plants were mainly Chamaephytes in the study area, accounting for 33.18%. Suffruticose-chamaephytes had the greatest number among the four subgroups of Chamaephytes in the areas of Dunhuang and Mazongshan. The lifestyle sequence was: Chamaephytes > Hemicryptophytes > Therophytes > Cryptophytes > Phanerophytes. 3) The Chamaephytes species occupied an important position in all altitude gradients, accounting for 59.15% of all life form species in the study area. With the increase of altitude, the Chamaephytes first increased and then decreased, reaching a maximum at 1 700 m altitude. The Hemicryptophytes species also showed a trend of first increasing and then decreasing with the increase in altitude. The Phanerophytes and Cryptophytes species accounted for a small proportion. The therophytes accounted for less than 10.00% of the entire elevation gradients, and had little fluctuation with the increase of altitude. Conclusion: The regional vegetation is dominated by shrub or semi-shrub vegetation in the areas of Dunhuang and Mazongshan, which is mainly distributed at 1 000~3 000 m altitude. The community life forms are dominated by Chamaephytes and Hemicryptophytes, and show a single peak distribution pattern of first rising and then falling with the altitude gradient.

Objective: This study aims to explore the responses of water resources of Platycladus orientalis to various water conditions, so as to provide scientific support for managing P. orientalis plantations in Beijing mountainous area. Method: P. orientalis, a typical afforestation species in Beijing mountainous area, was used as the study object. Three consecutive years with different annual precipitation were targeted to analyze the water source characteristics of P. orientalis under different annual precipitation conditions, and the annual precipitation in 2015, 2016, and 2017 was 580 mm, 649.8 mm, and 309.3 mm, respectively. The stable hydrogen and oxygen isotope technique, and MixSIAR model were used to analyze water resources. Simultaneously the climate data were collected, and the soil water content in the plot was measured, and the relative extractable water (REW) of soil was calculated. All the data were used to analyze the water use patterns of P. orientalis under different water conditions. Result: 1) The REW of deep soil was significantly higher than that of shallow soil (P < 0.05), and rainfall significantly increased the REW of each layer. REW in rainy season is significantly higher than that in dry season. In the three years, the REW of shallow soil in 2016 (0.341) and 2017 (0.360) was significantly lower than that in 2015 (0.423) (P < 0.05), while the REW of deep soil in the three years was not significantly different, which was 0.613, 0.618 and 0.587 in chronological order. 2) The contribution rate of deep soil water was generally greater than that of shallow soil water, but the contribution rate of shallow soil water increased after rain, with 45.7% after rain and 44.5% without rain, respectively. In different seasons, P. orientalis had higher utilization of deep soil water in the rainy season (56.2%) than in the dry season (54.8%). In different years, the utilization of the deep layer in dry year (2017) was 57.8%, and was significantly higher than that in normal year (2015) (54.1%) and rainy year (2016) (54.6%). Conclusion: P. orientalis mainly relies on deep soil water to maintain its water demand. Rainfall events and seasonal soil water variation do not significantly affect the water use strategy of P. orientalis, but the significant decrease in annual rainfall will cause P. orientalis to be more dependent on deep soil water.

Objective: This study aims to investigate the change pattern of transcriptomics of Camellia olefolia root in the early stage of its interaction with endophytic bacteria, so as to provide reference for clarifying the molecular mechanism of interaction between C. olefolia and endophytic bacteria. Method: An interaction system between endophytic Bacillus subtilis 1-L-29 and C. olefolia root was constructed. The transcriptomes of the interaction system were sequenced and analyzed by RNA-Seq at different time periods (0, 6, 12, 24 h). Result: 1) The transcriptome sequencing produced a total of 52 958 922 sequences, about 46.1 Gb, and 10 314 differentially expressed genes (FDR < 0.05 and |log₂FC|>1). With the extension of interaction time, the expression of differentially expressed genes showed a high-low-high trend. The number of differentially expressed genes at 6 h after vaccination was 6 306, of which 3 434 genes were significantly up-regulated and 2 572 were significantly down-regulated. At 24 h, a total of 903 genes were significantly up-regulated, and 526 genes were significantly down-regulated. At 24 h, a total of 1 195 genes were significantly up-regulated, and 1 384 genes were significantly down-regulated. 2) Go enrichment analysis showed that the biological process and molecular function of C. olefolia were changed most obviously after 6 hours of interaction. In the biological process, phosphate metabolism pathway, phosphorus-containing compound metabolism pathway, hormone response pathway, jasmonic acid metabolism pathway, bacterial response pathway, hormone-mediated signal pathway, cell response to hormone stimulation, phenylpropane biosynthesis pathway and so on were enriched. The activities of terpene synthase and dioxygenase in molecular functions were enriched. The membrane and intrinsic components of the membrane were enriched. 3) KEGG pathway analysis showed that the differentially expressed genes were mainly enriched into carbohydrate metabolism, amino acid metabolism, signal transduction, environmental adaptability and other pathways. The metabolic pathways enriched at 6 h after inoculation were significantly different from those at 12 h and 24 h, among which the significant differences were mainly plant hormone synthesis signaling pathway, plant pathogen interaction pathway and phenylpropanol biosynthesis pathway. 4) The genes with large changes in expression included auxin-inducible protein coding gene (SAUR), xyloglucan endoglycosyltransferase/hydrolytic protease coding gene (XTH), jasmonate ZIM domain protein coding gene (TIFY), calmodulin coding gene (CAM2), transcription factor MYB coding gene, disease resistance protein coding gene (RPM, RPS), respiratory burst oxidase coding gene (RBOHC), peroxidase coding gene (POD). Conclusion: In this study, for the first time, the living body interaction system has been used to analyze the endophytic bacteria-C. olefolia root interaction transcriptome at different time periods. The results indicate that endophytic bacteria can stimulate plant root growth, increase resistance, and induce immune response, but then the immune response gradually weakens. The results of this study laid a theoretical foundation for the analysis of the molecular mechanism of interaction between endophytic bacteria and C. oleifera.

Objective: BLH (BEL1-like homeodomain) gene family belongs to a transcription factor widely existing in plant, and its interaction with KNOX and other transcription factors are considered to play an important regulatory role in the development of plant secondary cell wall (SCW). The aim of this study is to clone BlBLH1 gene of Betula luminifera, then analyze its expression pattern and identify proteins that can interact with BlBLH1. Method: The BlBLH1 sequence in the genome sequence of B. luminifera was first identified by blast and other software. After verification by cloning, further bioinformatic analyses, including multiple sequence alignment and phylogenetic analysis, were also carried out. Quantitative Real-time PCR (qRT-PCR) was used to analyze the expression pattern of BlBLH1 in different tissues, organs and tension wood (TW). Yeast two hybrid technology was used to screen the proteins interacting with BlBLH1, and bimolecular fluorescence complementary (BiFC) was used to verify its interactions with some identified proteins in Arabidopsis thaliana cells. Result: The full-length of BlBLH1 was 2 128 bp in length with an open reading frame (ORF) of 1 830 bp. It encoded 609 amino acids harboring three conserved domains of SKY, BEL and HD. Phylogenetic analysis showed that BlBLH1 had the closest homologous relationship with A. thaliana BLH1. Expression analysis showed that the expression level of BlBLH1 in male inflorescence was the highest, followed by that in lignified stem. During the induction of tension wood, the expression level of BlBLH1 in tension wood was significantly higher than that in control. Through yeast two hybrid, 47 proteins, including structural proteins, enzymes and transcription factors, with strong interaction with BlBLH1 were identified, and the interactions of BlBLH1 with BlKNOX4 and BlKNOX9 were also verified by BiFC in A. thaliana protoplasts. Moreover, the expression patterns of these three genes in stems and tension wood were similar. Conclusion: In this study, BlBLH1 gene is cloned from B. luminifera. Based on the results of bioinformatics, expression and protein interaction analysis, it is inferred that BlBLH1 may be involved in the process of wood formation in B. luminifera, and interacted with KNOX proteins.

Objective: In this study, the FISH technology was used to track the behavior of specific chromosomes during meiosis of microsporocytes of triploid Populus alba × P. berolinensis 'Yinzhong', to clarify the pattern of chromosome pairing and separation, which would enhance understanding of the cytogenetic knowledge of chromosome behavior during meiosis of allotriploid plants and promote the polyploid breeding of poplars. Method: The anthers of triploid Populus alba × P. berolinensis 'Yinzhong' were used as materials to screen suitable enzyme solution and hydrolysis time. On this basis, the slides of meiotic chromosomes were prepared. The 45S rDNA probe was used to trace the chromosomal behavior of pollen mother cells during meiosis by fluorescence in situ hybridization (FISH) analysis. Result: 1) The suitable enzymolysis conditions for meiotic chromosome preparations of pollen mother cells of 'Yinzhong' were selected as the mixture with 3% cellulase and 1% pectolyase, enzymolysis at 37 ℃ for 3 h, combined with squashing coverslip and frozen coverslip removing. The preparations were characterized by good cell dispersion, thin cytoplasm, clean background, and clear chromatid morphology, which were suitable for FISH analysis. 2) The 45S rDNA probe signals were located on three homologous chromosomes of 'Yinzhong', which showed three different chromosome pairing types at metaphase I: one trivalent (Ⅲ), one bivalent and one univalent (Ⅱ+Ⅰ), and three univalents (Ⅰ+Ⅰ+Ⅰ), among them the frequency of cells with one trivalent was the highest, reaching 69.28%. The pairing types of Ⅱ+Ⅰ and Ⅰ+Ⅰ+Ⅰ accounted for 28.10% and 2.61% respectively, indicating that the chromosomes located by the 45S rDNA signals might be closely related, but the synaptic relaxation also existed. 3) Approximately 80.37%-93.44% of the cells presented a 2/1 distribution pattern from the anaphase Ⅰ to the metaphase Ⅱ, and about 63.00%-73.08% of the cells presented a 2/2/1/1 distribution pattern from anaphase Ⅱ to telophase Ⅱ, indicating that the chromosomes tended to follow a relatively normal separation in most of cells during the second meiotic division. However, in some cells, 1-2 chromosomes corresponding to the probe signals were observed to lag or form micronucleus in anaphase Ⅰ, metaphase Ⅱ, anaphase Ⅱ and telophase Ⅱ, which might be lost in the subsequent development. 4) There were some proportions of fusion nuclei in telophase Ⅱ cells with 3-4 45S rDNA probe signals, which might develop into gametes with 2n or even supernumerary chromosomes. Conclusion: FISH technology can be used to locate and analyze the specific chromosome behavior during the meiosis of poplars. Although the triploid 'Yinzhong' has abnormal chromosome behavior during the meiosis, the chromosome behavior located by 45S rDNA probe is relatively stable, which enriches the understanding of the meiotic chromosome behavior of allotriploid poplars.

Objective: In this study, the emergence, courtship and mating behavior of Dendrolimus suffuscus illustratus were investigated to explore its law of courtship and mating, and the attraction activity between male and female moths was tested through the experiment of trapping moths in the forest. This study aims to lay a foundation for the extraction and identification of sex pheromone of D. suffuscus illustratus. Method: This experiment was conducted in 2019 and 2020 to observe the eclosion and reproductive biological rhythm of D. suffuscus illustratus by artificially rearing in outdoor cages and trapping moths in the field. Result: The results showed that adult eclosion was concentrated in the dark period (19:00-2:00), and the daily eclosion peak was concentrated at 21:00. The eclosion period in 2019 was different from that in 2020. In 2019, the pupae in the cage began to emerge in early July, and reached the peak in late July (around July 29), and gradually decreased in mid-August. In 2020, the pupae in the cage emerged later than that in 2019, and began to emerge in mid-July, and entered the peak in mid-August (around August 11), and then gradually decreased. The number of emerged male moths was more than that of emerged female moths before the emergence peak, while the number of female moths was more than that of male moths after the peak. The emergence rates of adults in 2019 and 2020 were 83.8% and 88.5%, respectively. The sex ratio of male and female moths was 1∶1.04 (2019) and 1∶1.01 (2020). The average life span of unmated male and female moths was 4.05 and 5.84 d, respectively, and the average life span of mated female and male moths was 3.69 and 5.33 d, respectively. The courtship behavior of female moths was observed on the day of eclosion. The courtship behavior occurred in the dark period. The highest courtship rate of 1-day-old and 2-day-old adults was 40% and 45.5% respectively during the 6-8 h of the dark period. With the increase of age, the courtship behavior was advanced and the courtship rate decreased gradually. The rhythm of mating and courtship was consistent. The mating rate of 2-day-old adults was the highest (45%) at 6-8 h in the dark stage. With the increase of age, the mating behavior was advanced and the mating rate decreased. Both mated and unmated females were able to lay eggs. After mating, the average number of eggs laid by females was 154.1, and the average hatching rate was 94.8%. The average number of eggs laid by unmated females was 160.7 and the hatching rate was 0. The results showed that virgin moths could attract male moths in the field. The number of male moths trapped by 2-day-old virgin moths was significantly higher than that by other female moths. However, neither the blank trap nor the male moth attracted the adults. Conclusion: The emergence and reproductive behavior of D. suffuscus illustratus have obvious time rhythm. The day age is one of the main factors affecting the behavior of courtship and mating. With the increase of age, the time of courtship and mating is advanced, and the courtship rate and mating rate decrease.

Objective: This study aims to clarify the composition of gut fungi and bacteria of Agrilus mali in natural population in different developmental stages and different environmental conditions, and infer the possible effects on growth, development and physiological changes of the hosts. Method: The intact intestines of the adult (A) and larva (L) of Agrilus mali collected from wild fruit forest (W) and cultivated orchard (C) were dissected. The ITS2 sequence (fungi) and V3-V4 variant region (bacteria) of 16S rRNA were determined by Illumina MiSeq technology. The number of operating taxonomic units (OTU) of gut symbiotic microorganisms was counted, the species abundance, composition and alpha diversity were analyzed, and PICRUSt2 was used to predict function of OTUs. Result: A total of 177 028 ITS2 sequences of intestinal fungi and 253 712 16S rRNA high-quality sequences of bacteria were obtained from the gut microorganisms of A. mali. After cluster analysis, 285 (fungi) and 1 470 (bacteria) OTUs were obtained, respectively. For fungi, 5 phyla, 22 classes, 50 orders, 92 families, and 122 genera were identified; and for bacteria, totally 40 phyla, 103 classes, 231 orders, 364 families, and 594 genera were identified. There were 11 unique genera of fungi in CA, 28 in CL, 37 in WA, 12 in WL, and there were 2 unique genera of bacteria in CA, 223 in CL, 47 in WA, 68 in WL. A total of 7 genera of fungal communities and 21 genera of bacterial communities were determined as the core taxa. In addition, for intestinal fungal community, both the species diversity and richness of adults were greater than those of larvae, however for the bacterial community, species diversity in adults was greater than that in larvae, but the richness in the former was lower than in the later. Also, both the species diversity and richness of gut microorganism community of the larvae were much greater in cultivated than those in wild. Furthermore, a total of 74 fungal metabolic pathways and 426 bacterial metabolic pathways were annotated through MetaCyc Pathway. A total of 868 fungal metabolic pathways and 2 188 bacterial metabolic pathways were annotated through KEGG. Conclusion: There are differences in species and abundance of gut fungi and bacteria communities of A. mali at different developmental stages and in different environments. The species diversity and abundance of gut fungi in adults are greater than those in larvae. However, the intestinal bacteria in adults have lower abundance than that in larvae, suggesting that fungi play a significant role during developing process of adults while bacteria play a significant role during developing process of larvae. Additionally, although the species and abundance of intestinal microorganisms are quite difference, their functions are almost the same, indicating that a fixed group or symbiotic bacteria play a role in the gut of A. mali, which may be the result of long-term co-evolution between A. mali and its host.

Objective: Based on the indoor burning experiment carried out in the combustion wind tunnel laboratory, the particle size distribution and variation characteristics of the particulate matter released by surface fuel combustion in Korean pine plantation were quantitatively revealed, which would provide reference for the particulate matter released by forest fire. Method: The Korean pine plantation in the eastern mountainous area of Northeast China was selected as the object, and the fuel bed with different wind speed, fuel load and fuel moisture content was constructed. Based on 108 ignition experiments in the combustion wind tunnel laboratory, real-time monitoring was carried out by using the dissolved aerosol monitor (TSI Dust Trak 8533, USA), and random forest algorithm was used to establish a prediction model for particles of different sizes. Result: Wind speed was one of the most important factors affecting the mass of the four particle matter sizes. PM₁ was most affected by wind speed (37.207%) and temperature (25.651%), and was least affected by fuel moisture content (8.304%); PM_2.5 was most affected by wind speed (43.293%) and fuel load (22.855%), and was least affected by combustion efficiency (7.509%); PM₄ was the most affected by wind speed (43.552%) and fuel load (21.225%), and was least affected by fuel moisture content (6.841%); PM₁₀ was most affected by wind speed (40.832%) and fuel load (23.337%), and was least affected by fuel moisture content (6.946%). The R² of prediction models for PM₁、PM_2.5、PM₄、PM₁₀ based on the random forest algorithm were 0.804, 0.810, 0.806 and 0.812, respectively. Conclusion: The mass of particulate matter is positively correlated with wind speed, fuel load, fuel moisture content, and combustion efficiency (>80%), and negatively correlated with temperature and relative humidity. In general, the random forest algorithm can be used to better analyze the complex relationships between various variables and the mass of particulate matter. The observed range of particulate matter released from surface fuel combustion in Korean pine plantation is 1.72-56.04 g, and the predicted range is 5.67-36.33 g, which provides a data basis for the establishment of pollution source emission inventories and occupational exposure standards for fire-fighting practitioners.

Objective: This paper aims to study the feasibility of forest fire image information extraction and data analysis by only using one high-resolution remote sensing image (Planet Labs, PL), so as to provide reliable remote sensing data source and extraction methods for forest fire assessment. Method: In this study, the burned area of the "5·2" big forest fire in Bilahe in 2017 was used as the study area, three phases of PL images including before the fire, the year after the fire and one year after the fire were used as the data source, and the burned area was extracted by using ROIs. The variation characteristics of NDVI before and after fire interference were analyzed. Combined with the ground survey data, the difference normalized vegetation index (dNDVI) was used to divide the fire severity level, and the threshold was verified based on the classification standard of Luo Dekun fire damage levels. The damage status of vegetation in the burned area was evaluated to obtain the spatial distribution pattern of the degree of fire. Result: Fire disturbance led to a sharp decrease in NDVI values, and the NDVI value slightly increased one year after fire, indicating that the ability of vegetation restoration was very limited. The 3 m high spatial resolution of PL Remote Sensing Image made its RGB image highly saturated and every land class clear, and directly classified the land cover types. The training sample separation was above 1.91, the land cover types could be divided into 4 types: forest, herbaceous swamp, road and river. The classification accuracy was 98.05% and the Kappa_Coefficient value was 0.95. The fire severity was classified into 4 levels: unburned area, light burned area, moderate burned area and severe burned area. The overall classification accuracy was 91.55%, and the Kappa_Coefficient was 0.91. The total study area in Bilahe was 10 711.18 hm², and the burned area was 10 130.31 hm², accounting for 94.58% of the total fire area. Most burned area was light burned one with 5 700.78 hm², accounting for 53.22% of the total fire area., The moderate burned area was secondary, with an area of 3 035.12 hm², accounting for 28.34%. The damaged forest area affected by moderate burned was the largest, up to 6 167.48 hm², accounting for 60.88% of the total burned area. The secondary damaged forest area was in the light burned region, reached to 1 846.93 hm², accounting for 29.95%. The damaged forest area in the severe burned swamp region was the least, accounting for only 22.60%. The damage of herbaceous swamp was less, with a burned area of 3 962.86 hm², of which 97.25% of burned swamp area was concentrated in the light burned region. Conclusion: Compared with the traditional research methods, the research method used in this paper can achieve more accurate results in the analysis of forest fire in Bilahe, with higher classification accuracy, more reliable results and more efficient data processing. At the same time, PL remote sensing has ultra-high frequency time resolution, which covers the whole world once a day, and satisfies the requirements of covering different research areas to a great extent.

Objective: In this study, we investigated the temporal and spatial distribution pattern of sympatric Rhinopithecus brelichi and Macaca thibetana in the northeast of Fanjingshan Reserve, in order to further understand the their interspecific relationship and adaptation characteristics to the environment. Method: From 2017 to 2020, 66 infrared cameras were deployed in different vegetation types and altitudes in the northeast of Fanjingshan Reserve to monitor the temporal and spatial distribution of R. brelichi and M. thibetana. Result: The results showed that M. thibetana were widely distributed in the whole study area, while R. brelichi were mainly located in high-altitude areas far away from tourist trails and the distribution range completely overlapped that of M. thibetana generally was found in variety of habitats, while R. brelichi showed specific selection for habitats. In terms of altitude selection, there was no significant difference (P = 0.27) in the distribution of M. thibetana over various altitudes, while an extremely significant difference (P < 0.01) was found in the distribution of R. brelichi at different altitudes, mostly occupying the habitats from 1 600-1 900 m altitude. In terms of the selection of vegetation types, there was no significant difference in the selection of vegetation types for M. thibetana (P = 0.27), while there was a very significant difference in the distribution of R. brelichi (P < 0.01), with their relative abundance being the highest in evergreen and deciduous broad-leaved forests. Nevertheless, R. brelichi and M. thibetana had the co-occurrence habitats. It was found that there were 45 co-occurring sites in which R. brelichi and M. thibetana met within 15 days, accounting for 68.18% of the total monitored sites and 91.84% of the sites where R. brelichi was ever detected. The spatial overlap of habitats was very high. There was no significant difference in meeting times of the two species at the same site (P = 0.48), and they appeared at the same site once every 5-6 days on average, without any seasonal difference (P = 0.35). R. brelichi and M. thibetana were completely diurnal animals, with R. brelichi more activity at dawn and dusk, and M. thibetana activity around midday. The daily activity patterns of the two species were significantly different (P < 0.01), with the overlap of 0.76. However, the daily activity patterns and the resulting overlap of the two species varied significantly among seasons (P < 0.01). Conclusion: This study has revealed the temporal and spatial distribution characteristics of R. brelichi and M. thibetana by using camera-trapping in the northeast of Fanjingshan Reserve, indicating that the niche of R. brelichi and M. thibetana varies temporally and spatially. This study provides scientific data for effective protection of R. brelichi and M. thibetana.

Objective: In order to prepare TiO₂@SiO₂-delignified wood(TiO₂@SiO₂-DW) with an enhanced photostability by suppressing photodegradation of remaining lignin in DW, SiO₂, a kind of UV light inert material, was coated on the surface of TiO₂ nanoparticles to form monodispersed TiO₂@SiO₂ with core@shell structure to suppress inherent photocatalytic activity of TiO₂, to remain UV shielding, Vis light transparent properties. Method: The monodispersed, anatase TiO₂ nanoparticles with size of about 8 nm, which modified with oleic acid, dispersed in cyclohexane, were prepared by liquid-solid-solution(LSS) method. Reverse microemulsion method was used to deposit SiO₂ onto the surface of as-prepared TiO₂ nanoparticles to form monodispersed TiO₂@SiO₂ with size of about 12 nm, core@shell structure, and a good dispersity in ethanol. The lignin was removed from natural wood by H₂O₂/HAc delignification method to form DW with well-preserved cellulose skeleton. TiO₂@SiO₂ was soaked/coated on the surface of DW, and subsequently mechanical pressing to form TiO₂@SiO₂-DW. TEM, XRD, FTIR, and UV-Vis were used to characterize morphology/monodispersity, crystallized phase, functional groups, and UV-Vis absorbance properties of both TiO₂ and TiO₂@SiO₂. SEM and EDS were used to demonstrate the coating of TiO₂@SiO₂ on the surface of DW. Parameters of L^*a^*b^* of DW and TiO₂@SiO₂ -DW were used to evaluate the photostability. Result: TEM images demonstrates that both TiO₂ and TiO₂@SiO₂ possess monodispersity with particle size of 8 and 12 nm, respectively. The photos reveal that both TiO₂ and TiO₂@SiO₂ have a good dispersity in cyclohexane and ethanol, respectively. XRD analysis indicates that the crystallized phase of TiO₂ core and SiO₂ shell are anatase and amorphous, respectively. UV-Vis reveals that, TiO₂@SiO₂ possess both UV shielding and Vis light transparent properties. Remaining lignin content of DW is as low as 0.8%. SEM/EDS and photos demonstrate that TiO₂@SiO₂ is uniformly coated on the surface of DW with original color and texture. The result of accelerating aging test indicates that, ΔE^* value of H₂O₂/HAc-DW and TiO₂@SiO₂-DW is 4.9±0.9 and 2.3±0.3, respectively, due to the contribution of both 0.8% remaining lignin content and UV shielding of TiO₂@SiO₂. Conclusion: Based on the strategy of delignification and UV shielding of TiO₂@SiO₂, TiO₂@SiO₂-DW shows an enhanced photostability, better than those of TiO₂-, antimony-doped tin oxide-, and organic UV shielding compound protected wood, DW, and transparent wood. The mechanical strength of TiO₂@SiO₂-DW is better than that of natural wood. We might provide an alternative solution to deposit SiO₂ shell on the surface of the other nanoparticles with monodispersity, size of about 8 nm, oleic acid modification, prepared via LSS method.

Objective: In order to develop a novel approach of preparing lignin-based carbon materials, this paper has exploited a self-bubbling approach of industrial lignin for the preparation of carbon foams based on the physicochemical properties of lignin. Method: A self-bubbling process of lignin was realized using enzymatic hydrolysis lignin as the carbonaceous precursor, zinc chloride as a catalyst and phenolic formaldehyde resin as enhancer in the absence of additional foaming agents. The lignin-based carbons with a high surface area could be prepared from the mixture of lignin, zinc chloride and resoles through the steps of kneading, foaming, curing and carbonization. A thermogravimetric analysis, scanning electron microscope observation and nitrogen adsorption were employed to elucidate the mechanisms of lignin self-bubbling, the foaming processes and the texture of the resultant carbon foams. The effects of the dosage of zinc chloride and phenolic resin on the structure of carbon foams were studied by measuring the density, mechanical properties and porosity of the carbon foams. Result: The thermogravimetric analysis revealed that in the process of lignin self-bubbling, zinc chloride catalyzed the thermal decomposition of lignin leading to an obvious decrease in the temperature of lignin pyrolysis. As a result, the thermal decomposition and softening/plasticizing of lignin could simultaneously take place in the same temperature range, which allows lignin derived volatile pyrolysis products to work as a foaming agent in the softening/plasticizing lignin precursors. Meantime, phenolic resin provided the lignin-based foaming precursors with a higher tenacity and strength by crosslinking with lignin forming a three-dimensional network structure. The results showed that 160-180 ℃ is the suitable temperature range for lignin self-bubbling. The dosage of zinc chloride produced a significant effect on the density and porosity of carbon foams, and the dosage of phenol formaldehyde resin had a main effect on the cell size and open porosity. The self-bubbling process of lignin developed here produced lignin-based carbon foams with a relatively homogeneous cell bubble texture and high surface area, which had a bulk density of 0.26-0.46 g·cm^-3, porosity of 74%-85%, open porosity of 82%-94% and specific surface area of 524-1 055 m²·g^-1. Conclusion: The self-bubbling of lignin might be feasible to prepare lignin-based carbon foams with developed cell structure by regulating the temperature of thermal decomposition and softening/plasticizing of lignin. Therefore, it may be a graat potential to become a novel technology for the preparation of lignin-based carbon material.

Objective: Based on the cell characteristics of the processed image of cell on wood end faces, the search for corresponding machine learning methods can significantly increase the accuracy of identifying and realize efficient utilization and processing of wood, with the aim to provide an important basis for the identification and protection of rare wood species. Method: Using the cells on end faces of five kinds of wood(Abies nephrolepis, Larix olgensis, Picea jezoensis var.microsperma, Liriodendron chinense, Magnolia officinalis subsp. biloba) as research samples, a variety of differential images are extracted as data sets. Feature information is extracted by image processing, and support vector machine classifier(SVM) and AlexNet neural network are used for classification and recognition. According to the difference of wood end face cell distinction, BN (batch normalization) algorithm is added to the AlexNet neural network architecture for optimization, and a more efficient wood recognition method is designed. Result: The 29 680 enhanced images are divided into a 7∶3 ratio and saved in the training set and the test set folders. The test samples are labeled and put into the same folder, then conduct an overall batch test of the three classification algorithms. The results show that the overall recognition accuracy of the test set of the support vector machine classifier is 84.67%, the overall recognition accuracy of the test set of the AlexNet neural network is 88.76%, the overall recognition accuracy of the AlexNet neural network based on the BN algorithm is 91.15%. It can be seen that the recognition accuracy of the AlexNet neural network based on the BN algorithm is better. Conclusion: When the sample size is sufficient, the classification effect of the AlexNet neural network on images of cell on wood end faces is significantly better than that of the SVM classifier. The optimized AlexNet neural network based on the BN algorithm architecture is more sensitive to the linear features of the image, retains the fitting optimization of the AlexNet neural network and speeds up the optimization rate, which can effectively improve the classification accuracy and achieve high-precision wood classification.

Objective: This study was implemented to make a kind of steel-to-cross-laminated timber joint connected by self-tapping screws, and to explore the influences of different combinations on the mechanical properties of the joint. Based on the comparison between the existing theoretical models and the experimental values, the calculation model was optimized. Method: Six groups of shear tests with different combinations were carried out for self-tapping screws with angles of 45° and 90° by changing the screw tapping angles and combination forms, and loaded at a uniform speed of 1 mm·min^-1 according to the American standard ASTM D1761-12. The failure modes of the joints subjected to shear were recorded and analyzed, and the load-displacement curves, load-carrying capacity, stiffness and energy dissipation of each specimen were compared. Result: The main failure modes of the specimens were two screws cut off at the same time, the screws not cut off but plastic hinges produced, and the screws not cut off but pulled out at the same time. For all the 6 groups, there was a failure mode in which one side of the screws were cut off. In addition, there was a failure mode in which the screws for the group J-Cross45°T and S-Double45°T were pulled out instead of being cut off, and in group S-45°T-45℃ there was a failure mode in which plastic hinges were produced instead of being cut off. In this test, the load-carrying capacity and stiffness of groups J-Cross45°T, J-Double45°T were S-Double45°T were much higher than those of groups S-45°T-45℃, S-90°-45℃ and S-90°-45°T.The displacement corresponding to energy dissipation and load-carrying capacity of group S-90°-45℃ was the maximum. Conclusion: Among the 6 groups of specimens, Group S-Double45°T might have the best comprehensive mechanical performance, while group S-90°-45℃ could be suitable for the joints with high seismic requirements in the building.

Objective: Carpenter bees nesting on wooden components of ancient buildings brings damage to wooden structures. This study evaluated the carpenter bees damage grade for wooden components in order to provide a basis and an evaluation standard for the investigation and maintenance design of ancient building protection engineering. Method: Balsa woods damaged by carpenter bees were collected, then inspected nest structure by endoscopy and CT. Then the wood was cut through to observe the nest cell structure. Damage degree of wood structures was converted by tunnels volume and nest size. Result: The carpenter bee collected in this study was identified as Xylocopa(Koptortosoma) appendiculata. The endoscope could observe the main tunnel, and it could be found that the tunnel had 2-3 branches. CT scanning could provide an accurate understanding of nest structure. By dissecting the nests, it was found that the most nests of X. appendiculata were two parallel tunnels in two sides perpendicular to the entrance hole or two tunnels on one side and one on the other side. The average internal diameter of the tunnel was 1.55 cm, and the average length was 14.4 cm. The average of tunnels volume of each nest was 133.67 cm³. and the average of nest volumes was estimated at 1 436.58 cm³. Conclusion: The damage of carpenter bees in ancient buildings generally occured on the non load-bearing and independent wood components such as rafters, roof boarding or brackets. In order to estimate the degree of damage, this study evaluated the carpenter bee damage grade as 1-4 rate based on nesting habits: the wood component is found only one hole, it is classified as class 1 damage; when 2-3 holes are found, it is classified as class 2 damage; when 4-5 holes are found, it is classified as grade 3 damage; when more than 6 holes are found, it is classified as class 4 damage.

Objective: In this study, we measured the dynamic changes of photosynthetic physiological parameters, osmotic adjustment substances and protective enzyme system of mulberry leaves of different breeding methods under waterlogging stress. The main purpose of this study is to reveal the response strategies and differences of mulberry trees derived from different breeding methods to waterlogging stress, so as to provide a theoretical basis for the ecological restoration and sustainable development of mulberry under the adverse environment such as the water level fluctuation. Method: The seedlings of two mulberry varieties (SG and AY), which were reproduced by grafting (JJ) and cutting (QC), were selected as the test objects. and the waterlogging stress (YS) was simulated through covering a pot with another pot. The dynamic changes of photosynthetic parameters, chlorophyll content, osmotic adjustment substance content (soluble protein, soluble sugar, proline, malondialdehyde) and leaf protective enzyme activity (superoxide dismutase, peroxidase, catalase, ascorbate peroxidase) were measured on 0 d, 3 d, 7 d, 12 d, and 18 d of the waterlogging treatment to explore the effects of different breeding methods on the response of mulberry trees to flooding stress. Result: 1) The chlorophyll content decreased with the increase of waterlogging days, and the chlorophyll content of different varieties was only slightly different (P>0.05); 2)The diurnal variation of net photosynthetic rate (P_n) of CK-treated leaves showed a bimodal curve, while the mulberry seedlings with YS treatment showed a single peak curve of diurnal variation of P_n. QC breeding had slightly greater P_n value than JJ breeding did (P>0.05). The dynamic changes of photosynthetic parameters (P_n, G_s and Tr) of mulberry leaves in all treatments showed a trend of first decline and then increase, and the P_n value of QC breeding was slightly greater than that of JJ breeding (P>0.05). 3) With the extension of waterlogging time, the content of osmotic adjustment substances in the leaves of each treatment showed a downward trend. 4)Mulberry in all treatments could remove reactive oxygen species and maintain growth by increasing superoxide during the entire flooding period, but the changes of peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) showed a downward trend. Conclusion: The waterlogging stress reduces photosynthesis of mulberry trees, but there are differences in photosynthetic capacity between seedlings with different breeding methods. The photosynthesis ability of QC breeding mulberry is stronger than that of JJ breeding in the waterlogging stress. With the prolongation of waterlogging time, the two mulberry varieties in this experiment do not reduce the osmotic potential by accumulating osmotic condition substances. The SOD is the main defensive enzyme of mulberry in response to waterlogging stress. As for the response speed to waterlogging stress, there is interaction between breeding methods and different varieties. SG seedlings bred by QC respond faster than that bred by JJ, while AY seedlings bred by JJ respond faster than that bred by QC. This experiment shows that SG is suitable for QC breeding while AY is suitable JJ breeding. Whether different breeding methods have an impact on the physiological and ecological response of other mulberry varieties under waterlogging stress still needs further research and verification.