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Abstract:
  Objectives  With the application and development of digital technology of landscape architecture, big data technology and artificial intelligence technology have been gradually applied to landscape architecture, which have solved many problems. Machine learning technology, as a tool for processing big data and one of the core technologies of artificial intelligence, has gradually become a hot topic in landscape architecture research.   Methods  In this paper, the relevant practices at home and abroad in recent years have been systematically summarized and analyzed. Firstly, the application background is introduced to analyze the applicability of machine learning in landscape architecture. Secondly, based on different perspectives for machine learning to solve the problem in the fields of landscape architecture, the existing methods and processes of experiments at home and abroad are analyzed with examples from the site information extraction, landscape analysis and evaluation, self-generating system for planning schemes based on the deep learning algorithm, and then elaborate on the relationship among different fields of application of machine learning technology in landscape architecture and the relationship between different applications in the same fields.  Result  Finally, the possibility of building a landscape evaluation model based on multi-source data in the future, the possibility of applying the intelligent landscape analysis technology to the planning and design guidance, and the opportunity and challenge of constructing the future full artificial intelligence planning and design methods have been put forward.   Conclusion  From the technical level, constructing a comprehensive landscape evaluation model and landscpae analysis model based on a variety of data is a promising research direction in the future;On the application level, constructing digital planning and design methods based on various artificial intelligence methods with the integration of various intelligent technologies, the integration of multi-source data and the combination of practical planning and design projects is an important trend of machine learning in the future.
Abstract:
  Objective  As an indispensable process in the production and processing of MDF, abrasive belt grinding directly affects the processing efficiency and surface quality. At present, the research foundation on the grinding of wood materials is relatively weak, and most of them use metal grinding and solid wood as the research object. There are very few researches on the abrasive belt grinding of wood-based panels. In actual production, the selection and replacement of abrasive belts mostly rely on the experience of workers. The research can provide scientific basis and theoretical support for the selection and replacement of abrasive belts in actual production, and promote the development of wood processing technology and abrasive belt manufacturing technology in the direction of high efficiency and intelligence.  Method  This study used medium density fiberboard as the experimental material to test the grinding efficiency and surface roughness during abrasive belt grinding. Combining with the three-dimensional topography, the study analyzed the effect of abrasive belt wear on the material removal rate and surface roughness, and made predictions on the life of the abrasive belt.   Results  In the initial stage of MDF grinding, the abrasive grains are sharp and the material removal rate is high, but as the abrasive grains break and fall off, the material removal rate decreases faster. The material removal rate in the middle period of grinding tends to be dynamic and stable. In the later period of grinding, the material removal rate decreases again as the abrasive grains are further passivated and partially flaked off. As the number of grinding increases, the abrasive grains gradually become passivated and the diameter of the tip increases during the continuous wear process, leaving a widening grinding mark on the surface of the specimen, and the surface roughness of the specimen shows a downward trend. The roughness values in the early and late stages of grinding are relatively scattered, which in the middle stage are relatively concentrated and have good convergence. While the surface roughness of the abrasive belt is relatively concentrated in the early and late grinding stage, and the value in the middle stage is relatively scattered. In the case of the 120-mesh abrasive belt used in the test, when the material removal rate is used as the evaluation index, the cumulative grinding length of 23 096 m is the end of the service life of the abrasive belt. When the grinding surface roughness is used as the evaluation index, the service life end of the abrasive belt is when the cumulative grinding length is 18 375 m.   Conclusion  Abrasive belt wear to failure can be roughly divided into three stages. The grinding efficiency is directly proportional to the sharpness of the abrasive particles involved in the grinding and the number of effective abrasive particles. Abrasive belt wear has a greater impact on the surface roughness of grinding. When the purpose of the grinding process is different, the evaluation results of the abrasive belt life are different according to different inspection indicators. The life of the abrasive belt can be reasonably predicted by the change trend of the material removal rate and the surface roughness.
Abstract:
  Objective  Populus qiongdaoensis is a plant of the Populus genus found in tropical regions of China. So far, there is few studies focus on its classification and evolution. This study aims to understand the classification and evolution of P. qiongdaoensis in genus by third-generation full-length transcriptome sequencing and other methods.  Method  Based on the Pacbio Sequel sequencing technology, the complete full-length transcript data of P. qiongdaoensis, P. canadensis and P. simonii under heat stress were obtained. Then, the non-synonymous substitutions (Ka), sense substitution (Ks) and Ka/Ks value of homologous genes of three Populus were calculated. We further compared the expression patterns of orthologous genes under heat stress, and constructed the phylogenetic tree of five species to analyze the genetic relationship of Populus by combining the orthologous genes of P. trichocarpa and S. suchowensis. Finally, we cloned nuclear genes (nrDNA; UDP-SQ and POPTRDRAFT_575699) and chloroplast genes (cpDNA; atpⅠ and trnF) of P. qiongdaoensis to analyze the polymorphism of these gene sequences in the population of P. qiongdaoensis,calculated the intraspecific genetic distances of P. qiongdaoensis, and the interspecific genetic distances between P. qiongdaoensis and 19 species (Five Populus groups and one out-of-class group). Based on the maximum likelihood method and the minimum evolution method, the evolutionary tree of P. qiongdaoensis and 19 species were constructed to analyze the genetic relationship of P. qiongdaoensis.   Results  Third-generations of transcriptome sequencing obtained a total of 660 groups of orthologous genes from P. qiongdaoensis, P. canadensis and P. simonii. The average of Ks was 0.1505, the peak value was 0.02, and the ratio of Ka/Ks < 1 was 97.27%, showing the close relationship of the three Populus. Analysis of orthologous gene expression patterns revealed that they have the same expression pattern under heat stress. The average genetic distance of four genes including atpⅠ, trnF, UDP-SQ and POPTRDRAFT_575699 between P. qiongdaoensis and 19 species was 0.011, indicating that genetic relationship between P. qiongdaoensis and poplar group was closest.   Conclusion  The analysis of orthologous genes based on third-generation full-length transcriptome sequencing revealed that P. qiongdaoensis has a close relationship with other Populus. The results of genetic distances and constructing evolutionary trees show that P. qiongdaoensis has a close relationship with Leuce by cloning sequences of cpDNA and nrDNA genes. The polymorphism and evolutionary branch confidence of cpDNA were significantly higher than that of nrDNA, indicating that cpDNA was more capable of species discrimination than nrDNA genes in P. qiongdaoensis.
Abstract:
  Objective  Evaluating air quality scientifically is crucial for prevention and control of air pollution. Fuzzy synthetic evaluation (FSE) method has been widely used to comprehensively evaluate air quality, considering the influence of multiple pollutants. But the air quality level evaluated is often lower than the national AQI level, which weakens the impact of multiple primary pollutants on air quality. DS evidence theory has great advantages in uncertainty or ambiguity issues, such as the air quality levels. However, there are few studies to comprehensively evaluate air quality using DS evidence theory. Basic Probability Assignment (BPA) and evidence conflicts are key issues in DS evidence theory, that may lead to counterintuitive results.  Method  Therefore, in order to establish a highly reliable BPA, Pearson and Spearman correlation coefficient were used to analyze the air pollutants concentration data. And a progressive DS evidence theory strategy (Pro-DS) was proposed to avoid the conflict of evidence fusion. Thereby, a comprehensive evaluation model of ambient air quality based on Pro-DS was established. Then, the Pro-DS model was applied to Tianjin’s air quality evaluation in 2019. Finally, this paper proposed the Comprehensive Pollution Relative Coefficient (CPRC) to quantify the air quality under the action of multiple pollutants.  Result  Taking the AQI level as an indicator, the F1-score of Pro-DS method was 4.58% to 27.46% higher than that of the widely used models based on FSE, which validated the superiority of the Pro-DS model. Since the AQI standard is determined by a single pollutant, the F1-score of all FSE models was lower than 50%. However, taking the CPRC as an indicator, the F1-score of all FSE models exceeded 89.0%, which validated the effectiveness of CPRC. Experimental results showed that Pro-DS model had an F1 score of 93.1%, superior to other widely used FSE models.   Conclusion  The comprehensive air quality evaluated by Pro-DS model is lower or higher than the air quality evaluated by AQI, which better reflects the comprehensive effect of multiple pollutants on air quality. In this paper, the Pro-DS model can comprehensively evaluate the air quality, and the CPRC indicator can rank the degree of daily pollution, which can provide a substantial reference for the construction of ecological environment projects.
Abstract:
  Objective   This study aims to explore the impact of landscaping waste mulching on the soil fertility of urban green spaces, in order to provide a basis for the resource utilization of landscaping waste to solve urban green space soil problems.   Method  The Old Summer Palace, a typical urban green space soil in Beijing, was taken as the research object. Through field experiments, four different treatments were set up: no covering (CK), the upper layer was wood chips + the lower layer was the landscaping waste compost for 15 days (A), the upper layer was wood chips + the lower layer was the landscaping waste compost for 30 days (B), the upper layer was wood chips + the lower layer was the landscaping waste compost for for 60 days (C), and then analyzed and measured in the laboratory. Combined with the modified Nemerow index method, the comprehensive soil fertility index was calculated. Pearson correlation and stepwise regression analysis were used to analyze the effects of different mulching treatments on soil fertility.  Result  In 0−10 cm soil layer, the content of soil available phosphorus and available potassium were significantly increased by C mulching treatment (P < 0.05); in 10−20 cm soil layer, the content of soil available potassium were significantly increased by C mulching treatment (P < 0.05). The comprehensive fertility index of soil showed that the comprehensive fertility of 0−10 cm soil layer was significantly improved by C mulching treatment (P < 0.05). The Fimin value in the modified Nemero index method and stepwise regression analysis showed that the limiting factors of soil comprehensive fertility were soil bulk density and available phosphorus, soil organic matter was the most important factor affecting soil comprehensive fertility, followed by soil available phosphorus and soil bulk density.  Conclusion   In conclusion, landscaping waste mulching had different degrees of influence on soil physicochemical properties and comprehensive fertility. The results showed that treatment C is the best mulching scheme. In the future research, we should pay more attention to the dynamic change and improvement of the main influencing factors of soil fertility (soil organic matter, soil bulk density and available phosphorus).
Abstract:
  Objective  Forest carbon storage is an important indicator of the composition and functions of ecosystem. It will be benefit to forest resource management by investigating the state of forest carbon storage. The LiDAR can be used to monitor forest resources. There are some problems existed in forest parameter estimation, such as different models, uncertain variables, and lack of variables that are meaningful for forest stand three-dimensional structure. Therefore, it is necessary to select appropriate stand variables and models for forest monitoring.  Method  This paper used UAV lidar point cloud and sample plots data to analyze the plantation in Wangyedian forest form of Kalaqin banner, Chifeng city, Inner Mongolia autonomous region. The multiple linear model and the multiple power models were be used to estimate the forest carbon storage using different variables, and select the optimal model.  Result  (1) The nonlinear models (R2 = 0.66−0.86, rRMSE = 23.51%−9.91%) were better than linear models (R2 = 0.52−0.85, rRMSE = 27.70%−12.38%). (2) The mean height of point cloud and canopy cover were used as basic variable. The combinations of different variables were emulated to select the best model of forest parameters. The nonlinear model based on average height of the laser point cloud, canopy cover, height variation coefficient and leaf area variation coefficient (R2 = 0.86, rRMSE = 9.91%) had the highest estimating accuracy.  Conclusion  The vertical structure variables could improve the estimating accuracy of carbon storage of plantations using LiDAR. The non-linear model is more suitable for the estimation of carbon storage of plantations.
Abstract:
In recent years, with the aggravation of climate change and human activities, the global forest area continues to reduce, forest quality keeps declining, and the ecological and environmental events occurs frequently. Thus, forest health issues have received unprecedented attention, and have become an important part of the ecological civilization strategy. China’s forest resources continue to grow, but it also faces some problems, such as single afforestation structure, low stand quality and weak ecological stability. How to evaluate forest health systematically and accurately is still a difficult problem. Compared with the traditional ground survey methods, remote sensing technology has the advantages of macroscopic, timeliness and economic efficiency. With the rapid development of high-resolution remote sensing and artificial intelligence technology, it is possible to overcome the problem of forest health assessment. In order to systematically evaluate the potential of new remote sensing technology, this paper points out the existing paths and methods on the basis of literature analysis, including: (1) through bibliometric analysis, four core contents of forest health assessment (vitality, organizational structure, resistance and resilience) and four key issues (tree species classification, forest vitality, forest pests, drought threat) were identified. (2) Systematically interpreting the advantages and disadvantages of existing remote sensing technologies from three angles, namely, different scales (single tree stand ecosystem landscape), different platforms (near ground remote sensing, aerial remote sensing satellite remote sensing) and different sensors (including RGB cameras, multi/hyperspectral cameras, lidar, thermal infrared cameras, microwave radars and chlorophyll fluorescence scanners). (3) Focusing on four key issues, this paper expounds the application path and method of remote sensing technology to evaluate forest health in recent years. Furthermore, this paper points out the challenges and opportunities, including multi-source fusion analysis, forest health monitoring network and near ground remote sensing, forest health big data application, in order to provide reference for the intelligent management of forest resources in China.
Abstract:
  Objective  Aminopeptidase N(APN) is a class of important kind of BT receptor protein in insect midgut. The mechanism of Cry toxin produced by Bt bacteria to kill insects has been controversial in the academic research, but it is generally believed that the binding of toxin and Bt receptor protein is the necessary link to its virulence. the APN1 gene of Lymantria xylina was studied by gene cloning, biological information analysis and expression patterns, with the purpose to provid a reference for the subsequent study of APN gene family, other Bt receptor proteins and the mechanism of Cry toxin.  Method  APN1 was cloned by cDNA from midgut of the moth as template in a PCR system. Biological analysis and real time quantitative PCR(qRT-PCR) were performed to analyze to the expression pattern of LxAPN1 gene in different ages and tissues of Lymantria xylina.  Result  The full-length DNA of APN1 gene was cloned from midgut of Lymantria xylina and named LxAPN1. The full-length sequence of LxAPN1 was 3 159 bp, ORF was 3 054 bp, encoding 1 017 amino acids. Sequence alignment and phylogenetic tree analysis showed that LxAPN1 and LdAPN1 were highly homologous, with signal peptide at N-terminal, zinc binding site HEXXH (X18) E and conserved region GAMENWG, and GPI binding site at the end. LxAPN1 was not expressed in egg stage, and expressed in 1-7 instar larvae, the expression of LxAPN1 decreased after larval stage; the expression of LxAPN1 in intestine was significantly higher than that in head and cuticle.  Conclusion  LxAPN1 was successfully cloned in the midgut of Lymantria xylina. LxAPN1 and LdAPN1 are highly homologous, and the distribution of phylogenetic tree is also very similar, which not only indicates the similarity between Lymantria xylina and Lymantria dispar, but also the similarity of APN1 function between them; The expression of LxAPN1 was the highest in the second instar larvae of Lymantria xylina. And the expression was the highest in the gut from 6 instar larvae, as an Bt receptor in the intestinal of Lymantria xylina.
Abstract:
  Objective  The cloning and function of effector gene of pine wood nematode (Bursaphelenchus xylophilus) were studied to reveal the effects of Bx-Hh-grl on the pathogenicity of the nematode, and to provide theoretical basis for the control of the nematode.  Method  Black pine (Pinus thunbergia) was inoculated with Bx1022 strain. Twenty days later, total RNA of the nematodes was extracted for transcriptome sequencing, and the transcriptome was set as the transcriptome of phytophagous phase. The total RNA of Bx1022 cultured on Botrytis cinerea was extracted for transcriptome sequencing, and the transcriptome was set as the transcriptome of mycophagous phase. The differentially expressed gene Bx-Hh-grl was screened by comparative analysis of the two transcriptomes. The transmembrane domain and signal peptide of Bx-Hh-grl encoding protein were predicted. The expression sites of Bx-Hh-grl were detected by in-situ hybridization. The expression of Bx-Hh-grl was interfered by RNAi to verify the important role of Bx-Hh-grl on the pathogenicity of pine wood nematode. Q-PCR confirmed that the RNAi effect was significant. The RNAi treated pine wood nematodes were inoculated into branches of 3-year-old black pine. The untreated pine wood nematodes (CK group) and ddH2O treated pine tree nematodes (Mock group) were used as the control groups to compare the differences of the incidences of black pines and the pathogenicity of differently treated pine wood nematodes.  Result  The differentially expressed gene Bx-Hh-grl was screened out from the transcriptomes of phytophagous phase and mycophagous phase, and the protein encoded by Bx-Hh-grl had transmembrane domain and signal peptide. The results of in situ hybridization showed that Bx-Hh-grl was expressed in the esophageal gland of pine wood nematode, which was consistent with the effector gene characteristics. Q-PCR results showed that the expression of Bx-Hh-grl in pine wood nematode was down-regulated after RNAi treatment, and the effect of RNAi treatment was significant. Inoculation experiments showed that the symptoms of Bx-Hh-grl-RNAi nematodes treated group showed significantly later than the CK group, and the Mock group remained healthy all the time.  Conclusion  Bx-Hh-grl is an effector gene related to the pathogenicity of pine wood nematode. Understanding the function of Bx-Hh-grl is beneficial to further clarify the pathogenicity of pine wood nematode, and lay a theoretical foundation for reducing the damage and controlling the nematode.
Abstract:
  Objective  The objective was to determine the root nitrogen uptake and its relationships with root morphological and chemical traits in Korean pine (Pinus koraiensis) at different ages, and to advance our understanding in the linkage between root resource acquisition strategy and tree ontogeny.   Method  We sampled young ((14 ± 1) years), middle-aged ((48 ± 3) years) and mature ((217 ± 4) years) individuals of Korean pine in a mixed broadleaved Korean pine forest at Liangshui national nature reserve, Heilongjiang Province. Root nitrogen uptake was measured in situ with a short-term 15N labeling hydroponic experiment, and root morphological and chemical traits were also determined concurrently.   Result  Root ammonium, glycine and total nitrogen uptake rate of Korean pine decreased gradually with the increase of age, while no significant change in nitrate uptake rate was found. Across all ages, the contributions of different forms of nitrogen to total uptake ranked in the order of ammonium (62% ~ 65%) > glycine (25% ~ 32%) > nitrate (4% ~ 12%). The contribution of nitrate to total nitrogen uptake increased with the increase of age, but no clear patterns were shown in ammonium and glycine. The percentages of glycine as molecular absorbed by roots were very similar across young, middle-aged and mature individuals, with the corresponding values of 78%, 81% and 80%, respectively. With tree age increased, root diameter increased significantly, showing negative correlations with uptake rates of ammonium, glycine and total nitrogen (significant correlation only found in glycine), but positive correlation with nitrate. By contrast, specific root length and specific root surface area decreased with increasing age, both of them were positively correlated with uptake rates of ammonium, glycine and total nitrogen (significant correlation only found in glycine), but negatively correlated with nitrate. Root tissue density and chemical traits did not show significant changes among tree ages, and exhibited very weak relationships with nitrogen uptake rates.  Conclusion  With the increase of tree age, root nitrogen uptake rate and preference of P. koraiensis are significantly changed, which may be related to the alternation of root morphological traits.
Abstract:
  Objective  By comparing differences in the selection and consumption of Meliboeus ohbayashii primoriensis to 3 kinds of plants (Juglans regia, Malus pumila, and Crataegus pinnatifida), and by analyzing the composition and content of plant volatiles, this research provides a solid basis for a further development of the plant source attractant for M. ohbayashii primoriensis.  Method  The leaves of three plants (J. regia, M. pumila, and C. pinnatifida) were used to determine host plant choice and consumption by this insect pest. Volatile components in the branches and leaves of these three plants were collected using the dynamic headspace method and were analyzed by gas chromatography-mass spectrometry. Furthermore, Chi-square test was used to analyze and compare the differences in behavioral responses of M. ohbayashii primoriensis adults in the volatiles emitted by these plants.  Result  Significant differences were found in the selection and consumption of the three plants by M. ohbayashii primoriensis. Adults displayed high feeding selectivity for J. regia and consumed J. regia leaves. Whereas they showed low feeding selectivity for M. pumila and C. pinnatifida, without consuming their leaves. A total of 45 plant volatile compounds were identified from the branches and leaves of these three plants, including five alkanes, eight esters, three aromatic hydrocarbons, 18 terpenes, two aldehydes, four alcohols and five ketones. In the experiment of behavioral responses, both male and female adults of M. ohbayashii primoriensis were attracted by camphene in obvious tendency responses, while only males were attracted by bornyl acetate, decanal and eucalyptol in a certain attraction.  Conclusion  J. regia can be used as a host plant to supplement the nutrition of adult M. ohbayashii primoriensis, whereas the leaves of M. pumila and C. pinnatifida are not suitable for consumption. Camphene, bornyl acetate, decanal and eucalyptol had a certain attraction effect on the adults M. ohbayashii primoriensis. These volatile components may play an important role during the identification and selection of host plants by adult M. ohbayashii primoriensis. These volatile components of branches and leaves may play an important role during the identification and selection of host plants by adult M. ohbayashii primoriensis.
Abstract:
  Objective  Thecodiplosis japonensis is a newly discovered forest pest invading China in recent years. It has caused a large area of the weakening and dying of the coastal shelter forest of Pinus thunbergii in Huangdao District, Qingdao City, Shandong Province of eastern China. As a new invasive species, basic research on the prevention and control of Thecodiplosis japonensis is extremely weak. In order to develop effective prevention and control technologies to contain the serious harm of Thecodiplosis japonensis as soon as possible and avoid further spread, this paper starts from the host identification mechanism, so as to develop targeted attractants for monitoring and killing.  Method  In this study, the sequence of the odorant binding protein TjapOBP1 was screened from the antennal transcriptome data of Thecodiplosis japonensis, and the 3D structure model of the protein was obtained by homology modeling. We evaluated the reliability of the model with Procheck, Verify_3D and ERRAT. TjapOBP1 was docked with 67 ligand molecules measured in the volatiles of Pinus thunbergii by AutoDock software.  Result  Procheck analysis showed that 95.5% of the amino acids of TjapOBP1 fell in the optimal reasonable region. Verify_3D analysis showed that 83.3% of the amino acid score was greater than 0.2. The ERRAT values of TjapOBP1 were 73.2%. To sum up, the modeling results had high reliability. Molecular docking results showed that β-Myrcene had the best binding effect with TjapOBP1, and the binding energy was −5.26. In addition, the binding energies of 2,6-dimethylocta-1,5,7-trien-3-ol, neryl acetate, sabinene, lavandulyl acetate and 1-isopropyl-4-methylenebicyclo[3.1.0]hex-2-ene with TjapOBP1 increased successively, but were all below −5.0. All these 6 chemicals may be the odors that can be recognized and bound by TjapOBP1.  Conclusion  The establishment of 3D structural model laid a foundation for further study of the function of OBP in Thecodiplosis japonensis. Molecular docking screened the host volatiles that may bind specifically to this OBP, thus providing support for the development of attractants.
Abstract:
  Objective  Based on the morphological characteristics, types, distribution and quantity of sensilla, the adaptability between the antennal, thoracic and abdominal tegument sensilla of Endoclita signifier larvae and their wormhole was investigated.  Method  Scanning electron microscopy combined with measurement, statistical analysis, and scale mapping were used to observe, describe and make statistics of the sensillum on antennal, thoracic and abdominal tegument of the 4th instar E. signifier larvae.  Result  The antennal sensilla of E. signifier larvae were mainly distributed at the end of the flagellum, consisting of eight pairs of sensilla, including three pairs of sensilla chaetica, four pairs of sensilla basiconca, and one pair of sensilla styloconica, which can satisfy the chemical and mechanical sensory needs of the larvae. The sensillum type on the surface of thoracic and abdominal tegument were Bohm’s bristle and three subtypes of sensilla chaetica. All sensilla chaetica had spiral lines, and sensilla chaetica typeⅡ was the most unique, with spinous protrudes on its outer wall, which play a role in the mechanical expansion and defense of the larvae.  Conclusion  The antennal, thoracic and abdominal tegument sensilla of E. signifier larvae were adapted to their living environment, and the results will provide basic support for subsequent feeding behavior, olfactory recognition, and selective adaptation of E. signifier larvae.
Abstract:
  Objective  The colonization of plant disease biocontrol agents in plant rhizosphere soil is one of the important factors affecting its biocontrol effect. In recent years, walnut anthracnose has caused serious harm to the development of walnut industry in Yunnan Province of southwestern China, and it has posed a serious threat to the development of walnut industry in the growing areas. In the early stage, Trichoderma hamatum YB-4-15 and Bacillus subtilis yb33, which are important biocontrol agents, were obtained indoors by screening biocontrol of anthracnose on walnut in rhizosphere soil of Guangming Village, Yangbi County, Dali City. To better promote the above biocontrol agents, the colonization of the above strains in the rhizosphere of walnuts should be firstly considered.   Method  Trichoderma spore suspensions of different concentrations were applied to sterilized rhizosphere of walnuts.   Result  The colonization amount of the two biocontrol agents in rhizosphere soil was regularly measured, and it was found that after one month of mixing the biocontrol agents to the rhizosphere soil, the colonization amount of T. hamatum was 2 × 104 cfu/g at lowest level to 5 × 104 cfu/g at maximum level. At the same time, the rifampicin-resistant B. subtilis yb33-Rif was usedto determine the colonization ability in sterilized soil and field soil, the colonization amount of tested bacteria ranged from 7.07 × 106 to 1.08 × 108 cfu/g, significantly lower in field soil than in sterilized soil, ranging from 1.03 × 106 cfu/g at lowest level to 7.53 × 106 cfu/g at maximum level. In addition, the two tested biocontrol agents were mixed in the rhizosphere soils of walnut, osmanthus, camphor and heather, and it was found that the two biocontrol agents were found to grow well in walnut rhizosphere soil.  Conclusion  The current study lays a solid base for future application of the two biocontrol agents in walnut fields.
Abstract:
  Objective  The bacterial canker of Populus euramericana is caused by the Gram-negative bacterium Lonsdalea populi. The rapid spread of the disease has seriously threatened the growth and development of P. euramericana and has caused great economic losses to the plantation. Two-component system (TCS) is the important signal transduction mechanism of Lonsdalea populi. Now, how the two-component system of poplar bacterial canker regulates the pathogenic process is still lack of systematic research. Therefore, the large-scale deletion mutation and mutant phenotype analysis of TCS in this study will provide genetic materials for further study on the pathogenic mechanism of poplar bacterial canker.  Method  In this study, 28 two-component gene deletion mutants of poplar canker pathogen strain L. populi N-5-1 were constructed by parental association, the differences in pathogenicity, growth, motility, biofilm formation and resistance of these mutants were analyzed by phenotypic analysis, and the regulation of two-component system coding genes on the pathogenicity of these mutants was studied.  Result  In this study, 36 recombinant vectors of two-component coding genes were constructed and 28 deletion mutants were obtained. Phenotypic analysis showed that 18 genes encoding TCS were involved in virulence of L. populi N-5-1. Among them, the pathogenicity of 8 mutants had obviously disappeared. In addition, the deletion mutants regulating motility and biofilm-forming ability and those deficient in stress response (metal ions, salt ions, antibiotic stress, etc.) were also screened.  Conclusion  In this study, five two-component genes significantly affecting the pathogenicity of L. populi were obtained, providing genetic material for future studies on the pathogenic mechanism of L. populi.
Abstract:
The latent infection was defined as a state of disease without evident symptoms in which the carrier harbors the disease agent because of the host resistance and unsuitable environment. Pine Wilt Disease is an important pine epidemic disease worldwide, and it is also the most serious forest disease in China. The latent infection of pine wood nematodes is prevalent in epidemic area of pine wilt disease. Until now, the mechanism of latent infection is still unclear it bring some difficult to prevent and control of pine wilt disease. Due to the asymptomatic carriers are easily recognized as health trees and retained during the infection trees cutting process, and attract vector insects to feed and lay eggs as a source of pathogen to cause the spread of pine wilt disease once again. Therefore, we should pay more attention on the mechanism, epidemiology, and rapidly identification of latent infection to put forward effective prevention and control strategies of pine wilt disease.
Abstract:
  Objective  Venom-allergen proteins (VAPs) are proteins secreted by pine wood nematode during the process of infesting pine trees. Such proteins may inhibit the defense response of pine trees, thereby facilitating the colonization and spread of pine wood nematodes in pine trees. In this study, the prokaryotic expression, polyclonal antibody preparation and expression pattern analysis of four VAPs were conducted to clarify the structures and functions of the VAPs of B.xylophilus (Bx-VAPs), in order to provide basic support for elucidating the mechanism of this kind of protein in the interaction between pine wood nematode and the host pine.  Method  Polymerase chain reaction (PCR) was used to amplify the fourBx-VAPs genes, and the expression levels of the fourBx-VAPs genes were detected by Real-time quantitative polymerase chain reaction (RT-qPCR) method. At the same time, the amplified full-length products of the four genes were cloned into the pET32b prokaryotic expression vector separately, and the recombinant plasmid pET-32b-VAPS were constructed. After the identification, the correct recombinant plasmids were transformed into Escherichia coli BL21DE3 for induced expression. The purified Bx-VAPs were used to immunize Balb/c mice respectively, and polyclonal antibodies were obtained after four immunizations; the antibody serum titer was determined by indirect enzyme-linked immunosorbent assay (ELISA); the proteins were identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western-blot (WB). Finally, using bioinformatics methods to analyze and predict the physical and chemical properties, secondary structure, surface properties and B cell epitopes of the proteins encoded by these four genes.  Result  The results showed that there were significant differences in the expression levels of the fourBx-VAPs genes of B.xylophilus during different developmental stages. Among them, the Bx-VAP1 and Bx-VAP2 genes were expressed in high level in the adult stage, and the Bx-VAP3 and Bx-VAP4 genes were expressed in high level in propagative third-larval instar (L3). The constructed recombinant plasmid pET-32b-VAPn induce and express the proteins with a molecular weight between 21 kDa and 31 kDa. The three purified polyclonal antibodies anti-VAP1, anti-VAP2 and anti-VAP3 all have higher effect on the B.xylophilus protein solution specificity, but the anti-VAP4 antibody failed to react with the protein solution ofB.xylophilus. The secondary structures of the four Bx-VAPs are dominated by alph-helix and random coils, all have signal peptides, SCP domains, and no transmembrane domains. Bx-VAP1 has many potential dominant B cell epitopes.  Conclusion  The protein size induced by recombinant plasmid pET-32b-VAPn is consistent with the predicted protein size. All are expression of inclusion bodies, the prepared polyclonal anti-VAP1、anti-VAP2 and anti-VAP3 have high titer and good specificity. Bx-VAP1 has potential B cell epitope advantages. This study provides experimental materials and basis for further research on the function of B.xylophilus VAPs protein and related pathogenic mechanisms.
Abstract:
  Objective  Remote sensing image classification technology plays a vital role in forestry monitoring operations such as forest resource surveys, ecological engineering planning and forest pest and disease control.  Method  the work proposes a remote sensing image classification method based on multi-headed self-attentive modules, which uses the convolutional neural network framework ResNet50 as the backbone network of the whole framework. The intermediate layers of the last three bottleneck layers of the ResNet50 network are replaced with multi-headed self-attentive modules, which enable the model to focus on the regions with the highest discrimination and thus improve the classification accuracy. The experiments in this study use three publicly available datasets, RSSCN7, EuroSAT and PatternNet, based on the Pytorch machine learning library, to train and test the framework, and add a comparison experiment with the accuracy of existing classification frameworks. At the same time, different batch sizes are used to train the proposed framework and test the classification effect.  Result  Experimental results show the average recognition rate of the proposed method on the three remote sensing classification datasets reached 91.30%, 97.88% and 97.37% respectively, which is better than the existing algorithms based on deep convolutional networks. Also, the total number of parameters of this algorithm is 2.08 × 107, which is also much lower than that of existing algorithms.  Conclusion  The results show that the proposed framework is able to achieve higher accuracy in a GPU-accelerated environment, reduce the number of parameters included in the framework, reduce the video memory consumption, and improve the accuracy of the classification results compared to existing remote sensing image classification frameworks.
Abstract:
  Objective  In order to investigate the distribution of non-structural carbohydrates (NSC) in major soil and water conservation tree species in typical black soil region and their interspecific differences at organ level.  Method  Five species of soil and water conservation trees (Caragana microphylla, Amygdalus triloba, Betula platyphylla, Acer negundo and Picea koraiensis) were selected as the research objects, the concentration of soluble sugar, starch and total non-structural carbohydrate (NSC) in different organs were determined and compared.  Result  Within the same tree species, the concentration of NSC and its components in different organs had significant differences (P < 0.05). The mean concentration of soluble sugar in leaves was the highest, and that in trunk was the lowest. The mean concentration of starch and NSC in roots was the highest. The average concentration of soluble sugar and NSC in shrub leaves were lower than those in trees, and the average concentration of starch and NSC in deciduous roots were higher than those in evergreen trees. Evergreen trees (Picea koraiensis) allocated more NSC in the aboveground part, while deciduous tree(Amygdalus trilobaBetula platyphyllaAcer negundo) species allocated more NSC in the underground part. Deciduous shrub species (Caragana microphylla and Amygdalus triloba) chose to allocate most NSC to fine roots and medium roots, deciduous trees (Betula platyphylla and Acer negundo) chose to allocate most NSC to coarse roots, and evergreen trees (Picea koraiensis) chose fine roots as the main tissue for storing NSC.  Conclusion  Acer negundo is not suitable for afforestation in arid area, but Picea koraiensis can be afforested under different site conditions. This study analyzed and compared the NSC allocation strategies of five species, reflecting the growth adaptation strategies of soil and water conservation species, in order to provide theoretical basis for scientific selection and cultivation of soil and water conservation plants.
Abstract:
  Objective  To achieve the value-added utilization of wood after high energy density microwave treatment, crack-filled type microwave puffed wood based metal composites (WMC) was prepared, which provided a reference for the efficient utilization of planted solid wood treated by microwave.  Method  Tin-bismuth low melting point alloy (LMA) was used to impregnate microwave puffed Pinus radiata wood to prepare WMC by vacuum impregnation method. The micro-morphology, thermal stability, surface contact angle and other properties of WMC were characterized and analyzed by SEM, EDS, CT, DMA, TG, DSC, XRD, FTIR, etc. Meanwhile, the compound mechanism of LMA and microwave puffed wood was discussed.  Result  LMA was filled in the cracks of the microwave puffed wood and forms a mechanical interlocking meshing structure with wood, making it tightly combined at the cracks and improving the interface bonding strength. The mass percentages of Sn and Bi in WMC were 25.97% and 31.13%, respectively. The CT scan image reconstructs the spatial distribution of LMA in WMC, realizes three-dimensional rendering of WMC visualization, and shows its unique texture. Compared with the untreated wood sample, WMC has higher storage modulus, loss modulus and char yield, and the thermal stability is improved. In addition, there were no new functional group characteristic peaks such as esters and ethers in WMC. The crystal structure of WMC was not destroyed, and the crystallinity of WMC shows an upward trend, increasing from 25.9% of the untreated wood sample to 38.6%. The surface contact angle is 172% higher than that of the untreated wood sample at 60 s, and the hydrophobicity was significantly improved.  Conclusion  In this study, a crack-filled microwave puffed wood based metal composites was prepared, the distribution of tin-bismuth alloy in microwave puffed wood was observed and modeled, and thermal stability and surface contact angle were characterized, which provided a new idea for the development of new wood products based on high energy density microwave treatment of wood.
Abstract:
  Objective  The quality of snow leopard monitoring images collected by infrared trigger cameras is uneven and the number is limited. An automatic recognition method of snow leopard monitoring images based on deep learning data expansion was proposed to improve the recognition accuracy of the snow leopard under limited samples.  Method  Improve the ResNeSt50 model with attention mechanism, the snow leopard monitoring images of Qilian Mountain National Park were used as the original data set, the non-snow leopard terrestrial wildlife images taken by the infrared trigger camera were used as the extended negative sample, and the network snow leopard images were used as the extended positive sample. Comparative experiments were conducted in turn based on the above three data sets. The model was gradually guided to focus on the key characteristics of individual snow leopards by choosing an appropriate expansion method, and the effectiveness of the data expansion was verified by using Gradient-weighted Class Activation Map.  Result  Results showed that the model trained with the original data set+expanded negative samples+expanded positive samples had the best recognition effect. The Grad-CAM showed that the model correctly focused on the individual pattern and spot characteristics of the snow leopard. Compared with the recognition model based on Vgg16 and ResNet50, ResNeSt50 achieved the best recognition effect, the test set recognition accuracy rate reached 97.70%, the precision rate reached 97.26%, and the recall rate reached 97.59%.  Conclusion  The model trained by the original data set+extended negative sample+extended positive sample data expansion method proposed in this paper can distinguish the background from the foreground, and has a strong ability to discriminate the characteristics of the snow leopard itself, and the generalization ability is the best.
Abstract:
  Objective  In this study, we cloned the odorant receptor gene (LdOR2) and determined the expression levels of this gene in developmental stages and different tissues of the Lymantria dispar and its behavioral response to CO2 stress. The results will provide a theoretical basis for clarifying the olfactory response mechanism of the L. dispar under climate change.  Methods  The LdOR2 gene was cloned through transcriptome library screening, and its characteristics were analyzed by bioinformatics. The expression levels of LdOR2 gene in different developmental stages and tissues as well as in different CO2 concentrations (397, 550 and 750 μL/L) was determined by Real-time fluorescence quantitative PCR technology. In addition, RNA interference (RNAi) technology was used to study the behavioral responses of L. dispar adults silenced by LdOR2 at different CO2 concentration.  Results  The open reading frame (ORF) of LdOR2 gene in L. dispar was 1 203 bp, encoding 400 amino acids. The molecular weight of the LdOR2 protein was 45.76 kDa and the theoretical isoelectric point was 8.22. The phylogenetic tree showed that the LdOR2 in L. dispar was closely related to MsepOR24 Mythimna separata and AdisOR21 in Athetis dissimilis, and clustered into one group. RT-qPCR results showed that LdOR2 was expressed at all developmental stages of the L. dispar, with the highest expression level in female pupae and the lowest expression levels in male adults. In different tissues of female and male adults, the expression levels in antennae were significantly higher than those in other tissues (P < 0.05), but showed no difference between the antennae of female and male. The expression of LdOR2 gene decreased under high CO2 concentration. Compared with the control group, the expression of female antennae under 550 μL/L and 750 μL/L conditions decreased by 21% and 29% (P < 0.05), respectively, and the expression levels of antennae of male L. dispar adultsdecreased by 43% and 7% (P < 0.05). After LdOR2 gene silencing, the tendency of female and male L. dispar adults to eugenol and cis-3-hexene-1-ol was weakened, while the response rates of the L. dispar silencers to seven volatiles decreased under high CO2 concentration.  Conclusion  LdOR2 plays an important role in the odor recognition of L. dispar. The sensitivity of L. dispar to odor was affected by the expression levels of LdOR2 gene regulated by the changes of CO2 concentration.
Abstract:
  Objective  GRAS family is a plant-specific transcription factor family, characterized by a highly conserved carboxyl terminus domain. Previous studies have shown that GRAS transcription factor is one of the key transcriptional regulators in plant stress response. The purpose of this study is to analyze the salt tolerance of GRAS transcription factor gene BpPAT1 gene in B. platyphylla, so as to lay a foundation for elucidating the molecular regulation mechanism of GRAS transcription factor in response to salt stress. Our work enriched the research on the molecular mechanism of the GRAS transcription factors of woody plant in response to stress.  Method  In this study, one GRAS transcription factor gene was screened from the transcriptome data of B. platyphylla under salt stress and named as BpPAT1. Multiple sequence alignment and phylogenetic tree were used to analyze the genetic relationship between BpPAT1 and other organism’s GRAS family genes. Real-time fluorescence quantitative PCR (qRT-PCR) method was used to analyze the expression pattern of BpPAT1 in root, stem and leaf tissues of B. platyphylla under salt stress and normal condition, to identify whether it responded to salt stress or not. In order to further analyze the stress tolerance function of BpPAT1, plant overexpression vector (pROKII-BpPAT1) and inhibitory expression vector (pFGC5941-BpPAT1) were constructed. Transient overexpression and inhibitory expression of BpPAT1 gene and control B. platyphylla plants were obtained by Agrobacterium tumefaciens-mediated transient genetic transformation system. The physiological indexes related to salt tolerance were measured to identify whether the BpPAT1 was associated with salt tolerance in transient expression of BpPAT1 and control plants under salt stress.  Results  The results of multiple sequence alignment and phylogenetic tree analysis showed that BpPAT1 protein had the sequence characteristics of GRAS family and was closely related to AtPAT1 protein in A. thaliana. The results level of qRT-PCR showed that the expression of BpPAT increased significantly in B. platyphylla plants after 6 hours of salt stress, indicating that BpPAT1 could respond to salt stress signal.The measurement results of the physiological indexes of stress resistance showed that the overexpression of BpPAT1 in B. platyphylla could significantly increase the activity of peroxidase (POD) and superoxide dismutase (SOD), increased the content of proline, and decreased electrolyte leakage and malondialdehyde (MDA) content.  Conclusion  In conclusion, The BpPAT1 gene can respond to salt stress, overexpression of BpPAT1 significantly enhanced POD, SOD enzyme activities and proline content, decreased electrolyte leakage and MDA content under salt stress, thus improved ROS scavenging ability and salt tolerance of B. platyphylla.
Abstract:
  Objective  To lay the foundation of the development of new insect-resistant biological pesticides in trees, the insect-resistant function of the serine protease inhibitor PtrSPI of Populus tomentosa was studied.  Method  To analyzed the function of the serine protease inhibitor gene PtrSPI, the promoter and the expression pattern under feeding stress of Lymantria dispar larvaes of the gene PtrSPI in P. tomentosa was studied. To discuss the anti-insect ability of PtrSPI, the food intake, the body mass, the mortality and the serine protease enzyme activities of L. dispar larvae are studied after using the eukaryotic recombinant protein PtrSPI feeding L. dispar larvaes.  Result  The results showed that 5 elements related to plant resistance to disease and insects were in the promoter region of the serine protease inhibitor gene PtrSPI of P. tomentosa; the expression pattern of the gene PtrSPI in P. tomentosa leaves was firstly decreased and then increased after fed by L. dispar larvae, and the peak was 2.03 times than that of the control at 30 h; under the high concentration of recombinant protein (300 and 500 mg/mL), the food intake and the body mass of L. dispar larvaes was significantly inhibited, the mortality of L. dispar larvaes was up to more than 60% after 6 and 4 h, respectively, and the activities of the serine protease in L. dispar larvaes were significantly increased at the beginning of feeding.  Conclusion  This study verified the insect resistance of the serine protease inhibitor PtrSPI of P. tomentosa, and it provides theoretical basis and research materials for further research and development of new non-pollution and insect-resistance biological pesticides.
Abstract:
  Objective  The micro-scale environment is a very important human-scale outdoor spatial unit. Explore the influence mechanism of micro-scale land-cover type and pattern on microclimate is the theoretical basis of improving urban thermal environment with the help of landscape design strategies.  Method  Through field measurements, differences of daily air temperature (AT) and relative humidity (RH) among seven typical land-cover types of urban residential green space, and correlations between daily AT and RH and various micro-scale land-cover patterns as explained by landscape metrics were analyzed.  Result  During the four seasons, there were various differences in daily AT and RH among the seven land-cover types, and the order of the seven types varies seasonally. Overall, high canopy-density vegetation and water bodies type always had prominent cooling and humidifying effects, whereas highest AT and Lowest RH were always found in pavement type. Correlations between landscape metrics and daily AT and RH varied by season. Metrics reflecting the dominance and distribution of land-cover classifications had closer relationships with microclimate level in the micro-scale environment. The proportion and average patch area of land-cover classifications were the critical pattern characteristics that affect the daily AT and RH of micro-scale environment. And the fragmentation and aggregation also have certain influence.  Conclusion  When designing micro-scale thermal comfort outdoor space, increasing the proportion and patch area of high and moderate canopy-density vegetation, controlling the fragmentation and adopting aggregating layout can significantly reduce AT and increase RH. The hard pavement with high proportion, large area and concentrated distribution should be avoided to reduce its thermal regulation negative effect.
Abstract:
  Objective  In order to provide scientific proposals and theoretical basis for the integration and optimization of protected areas (PAs) in Liaoning Province, we analyzed the spatial distribution pattern and overlapping status of 235 PAs of six categories in Liaoning Province qualitatively and quantitatively.  Method  The nearest neighbor index analysis and kernel density analysis were used to evaluate the spatial distribution of the PAs. By calculating the proportion of overlap in each protected area mosaic, the overlap status of PAs in Liaoning Province was analyzed qualitatively and quantitatively. We also proposed a new method to calculate the overlap rate of multiple layers.  Result  (1) The nearest neighbor ratio of PAs in Liaoning Province was 0.904, indicating the aggregation distribution pattern of PAs in Liaoning Province. (2) The PA in Liaoning Province mainly formed four aggregation regions: deciduous broad-leaved forest in west Liaoning and north Hebei, mixed coniferous and broad-leaved forest in Longgang Mountains, grassland and cultivated vegetation in Liaohe Plain, northern part of wet land and deciduous broad-leaved forest in Liaodong Peninsula. (3) The PAs with overlap accounted for 50.43% (by amount) and 8.63% (by area) of the total PAs in Liaoning Province. The overlaps mainly occurred between nature reserves and natural parks, with a total area of 134, 421 hm2 occurred in 107 PAs. (4) There were 82, 13, and one overlapped patche (s) with two, three and four overlapped layers respectively in Liaoning Province. (5) Based on the concept of PAM, a total of 36 PAMs were recognized in Liaoning Province, of which eight had an overlap rate more than 50% (maximum of 81.34%), 6 less than 10% (minimum of 1.82%).  Conclusion  The high overlap rate of PAMs indicated over evaluation of the area and conservation service function of the PAs. In this case, we suggested that the PA overlaps should be merged, and appropriate reduction of the total area should be permitted during the integration and optimization of the PA system in Liaoning Province... Furthermore, given the low protection effectiveness of some regions worthy of conservation, e. g., the coastal areas at the southern part of the deciduous broad-leaved forest and wetland in Liaodong Peninsula, we suggested new PAs be established or expansion of the existing PAs to ensure the protection intensity and effectiveness of the PA system of Liaoning Province.
Abstract:
  Objective  In order to analysis the diversity of water adaptation strategies adopted by different tree species in same environment, here, we selected four typical suitable tree species with great differences in root distribution depth wood properties and growth speed .These species were Acer truncatum, Prunus cerasifera, Populus tomentosa and Robinia pseudoacacia and planted in Gaotang region, Shandong Province.  Method  In this study, we compared the hydraulic traits and iso/anisohydry evaluation of the leaves of these four species. The hydraulic traits included embolism vulnerability parameters Pressure-Volume (PV) curve parameters hydraulic structure and functional properties.  Results  The results indicated that different species selected different water adaptation strategies to adjust to the same environment. Among them, P. cerasifera and A. truncatum owned more conservative water adaptation strategies, while R. pseudoacacia and P. tomentosa adopted more adventurous water adaptation strategies; P. cerasifera is a fast-growing tree with shallow-rooted diffuse-porous wood, it had the strongest leaf embolism resistance (embolism vulnerability P50 is −2.67 MPa). Meanwhile, the water safety of P. cerasifera was very high (hydraulic safety margin HSM is 1.57 MPa), the water adaptation strategy was conservative; A. truncatum is a slow-growing tree species with shallow-rooted diffuse-porous wood, its leaves inclined to isohydraulic regulation (the hydraulic area is 0.049 MPa2).When drought stress is encountered, the stomata can be closed early to keep the leaf water potential and turbulence stable. Its P50 is relatively high and HSM is relatively low, showed low anti-embolism ability and low hydraulic safety. The adjustment range of leaf water potential is narrow. Its high Huber value (Hv) shows that it has high drought resistance. A more conservative water adaptation strategy has been adopted by it. R. pseudoacacia is a kind of fast-growing species, its leaves were inclined to aniso-hydraulic regulation, had strong anti-embolism ability, the range of leaf water potential was wide, the water adaptation strategy was more adventurous. P. tomentosa, is the fast-growing species with deep-rooted diffuse-porous wood and low sieve resistance. The water safety factor is close to limit (HSM is 0.0015 MPa). Its leaves owned the strongest ability to maintain turgor pressure (water potential at turgor pressure loss point ψtlp is −3.36 MPa), to ensure they could obtain water from deep soil under water when in shortage conditions. P. tomentosa selected more risky adaptation strategy.  Conclusion  In summary, trees could adopt different hydraulic traitsiso/anisohydry traits morphological and structural characteristics to select different water adaptation strategies to adapt the same environment. The diversity of water adaptation strategies is conducive to maintaining the stability of local ecosystem.
Abstract:
  Objective  In order to reveal the molecular mechanism of drug sensitivity of Bursaphelenchus xylophilus to provide a theoretical basis for the control of Bursaphelenchus xylophilus.  Method  In this study, the homologous detoxification gene Bx-pgp23 of Caenorhabditis elegans was obtained from the genome of Bursaphelenchus xylophilus, and PCR amplified the protein-coding region of the gene. Subsequently, the physicochemical properties, hydrophobicity, transmembrane distribution, phosphorylation sites, secondary structure, and tertiary structure of the protein the Bx-PGP23 were analyzed and predicted by bioinformatics. The effect of the Bx-pgp23 silencing on drug sensitivity of Bursaphelenchus xylophilus was analyzed by RNAi technology.  Result  Bioinformatics prediction showed that the stability coefficient of PGP protein was 38.31 and the hydrophilic coefficient was −0.018. The tertiary structure predicted that PGP protein had multiple amino acids involved in the formation of α-helix and β-sheet with multiple nucleotide-binding domains (NBD) and transmembrane domain (TMD). The gene silencing of Bx-pgp23 gene was performed by RNAi technology, after that the expression of Bx-pgp23 gene was changed to 42.65% of the original. The results of the bioassay experiment showed that the mortality rate of Bursaphelenchus xylophilus in the RNAi group increased by 7.2% and 6.4% compared with the control group after 24 h of treatment with 1.5 and 2.5 g/L of matrine solution. After tremeant for 48 h, the mortality rate of Bursaphelenchus xylophilus in the RNAi group increased by 9.0% and 7.2% compared with the control group.  Conclusion  Protein Bx-PGP23 was a stable hydrophilic protein with transmembrane efflux function. The Bx-pgp23 gene was successfully cloned and the dsRNA of the gene was synthesized. Bx-pgp23 gene silencing affected the sensitivity of Bursaphelenchus xylophilus to matrine solution and the mortality rate of Bursaphelenchus xylophilus in the RNAi group was significantly higher than the control group under the same mass concentration of matrine solution. The results indicated that the Bx-pgp23 gene plays a positive regulatory role in the regulating of drug metabolism in Bursaphelenchus xylophilus.
Abstract:
  Objective  Colletotrichum fructicola is a major pathogen causing anthracnose on Camellia oleifera, and leads to substantial losses annually. The domain analysis of transcription factor CfHac1 will help us understanding the CfHac1-regulated pathogenic mechanism of the pathogen and providing new insights to control this disease.  Method  We constructed the domain deletion vector by using point mutation technology and introduced it into the ΔCfhac1 mutant through the PEG-mediated protoplast transformation. The strains were selected by bleomycin and fluorescence, then functional analyzed in C. fructicola.  Result  The structure prediction revealed that CfHac1 contains one basic region-leucine zipper motif (BRLZ), which contains 58 amino acid residues. Comparing to the wide type and complemented strains, the mycelial growth rate, conidiation and appressorium formation rate of the Cfhac1ΔBRLZ were significantly reduced, and the Cfhac1ΔBRLZ strain was sensitive to dithiothreitol. The pathogenicity test showed that the Cfhac1ΔBRLZ lost the ability to infect C. oleifera leaves, which phenotype is consistent with ΔCfhac1 mutant.  Conclusion  The results showed that BRLZ is an important domain of CfHac1 and is essential for normal function of CfHac1 in C. fructicola.
Abstract:
  Objective  Physical and value of carbon sequestration of China’s forest resources should be calculated to find out the family background of China’s forest resources, understand the status of forest resources, and formulate a reasonable forestry development plan. Through the prediction of forest carbon stocks and carbon sequestration potential, it can improve the level of forest management and provide reference value for China to achieve the goal of carbon neutrality and at the peak carbon dioxide emissions in forestry development.  Method  Based on the data of 9 forest inventories from 1973 to 2018 in China, the total carbon stocks of forest resources in China were calculated using forest volume method, and the carbon stocks and values of forest resources were calculated according to the different forest types. This paper uses GM (1,1) grey model and power function model to predict the development potential of forest carbon sequestration in China, and analyzes the change rate of carbon sequestration under different management levels by constructing the regression model of forest growth per unit area and carbon storage.   Result  (1) Over the past 40 years, China’s average unit area volume of forest resources is 73.56 m3/ha, forest carbon stocks increased from 5.196 billion t in 1976 to 8.79 billion t in 2018, the average annual increase of 0.855 7 billion t/a. The total carbon stocks of forest resources (including forest, woodland and understory vegetation) increased from 12.506 billion t to 21.439 billion t; Among them, carbon stocks of plantation increased significantly, with an average annual increase of 5.05%. (2) The values of forest carbon stocks in China increased from 148.209 billion CNY in 1976 to 882.385 billion CNY in 2018, with an average annual increase of 17.480 billion CNY and a compound annual growth rate of 4.34%; Among them, the values of plantation carbon stocks increased by 8.24%. (3) The GM (1,1) grey model predicts that the forest carbon stocks will reach 10.013 billion t in 2030, the average annual increase of carbon sequestration will be 159 million t/year from 2018 to 2030, and the forest volume will reach 21.08 billion m3 in 2030; the forest carbon stocks in China will reach 18.032 billion t in 2060, and the average annual increase of carbon sequestration will be 236 million t/year from 2018 to 2060. The power function model predicts that China’s forest carbon stocks will reach 10.8 billion tons in 2030, the average annual carbon sequestration will be 225 million t/year from 2018 to 2030, and the forest volume is expected to reach 22.738 billion m3 in 2030; China’s forest carbon stocks will reach 21.227 billion t in 2060, and the annual increase of carbon sequestration will be 312 million t/year from 2018 to 2060. (4) Based on the average benchmark of forest carbon stocks in recent 15 years, the forest management level is increased by 5%, the forest carbon stocks will increase by 4.30% ~ 6.86%; By 10%, the forest carbon stocks will increase by 9.89% ~ 12.47%. By 15%, the forest carbon stocks will increase by 15.48% ~ 18.09%; By 20%, the forest carbon stocks will increase by 20.96% ~ 21.07%.  Conclusion  Without considering the influence of external factors such as economy and policy, based on the changes of forest biomass and volume, China’s forest carbon stocks and values are increased. According to this development trend, China can achieve the expected development goal of carbon neutrality and at the peak carbon dioxide emissions for forestry in 2030 and 2060. If the current forest management level is further improved, the change rate of forest carbon stocks will gradually increase, and the carbon sinks potential will be huge.
Abstract:
  Objective  SPL is a plant-specific transcription factor and plays crucial roles in the growth and development of plants. It participates in multiple processes such as plant phase transformation, flower development, sporogenesis, leaf and root development, and stress response. Exploring the cis-acting elements of the promoter region of the BpSPL6 gene, as well as the expression pattern under normal and stress conditions, this paper provides a reference for further study of the function of BpSPL6 gene and also provides a basis for understanding the stress resistance mechanism of Betula platyphylla.  Method  Using the total DNA of tissue-cultures B. platyphylla in this laboratory as a template, the 1 703 bp promoter sequence of BpSPL6 gene was cloned by PCR. The cis-elements of the promoter region were analyzed using PLACE and Plant CARE web tools. We constructed the BpSPL6 gene promoter-driven GUS expression vector, which was transformed into Arabidopsis thaliana. Transgenic A. thaliana was subjected to stress experiments, and GUS staining was used to analyze the expression pattern of the BpSPL6 gene promoter.   Result  A 1 703 bp promoter sequence of BpSPL6 gene was cloned from B. platyphylla genomic DNA. Sequence analysis showed that the BpSPL6 gene promoter included core promoter elements TATA-box and CAAT-box, as well as cis-elements for specific parts (root and pollen), hormone response elements (auxin, gibberellin, salicylic acid, abscisic acid) and dehydration response elements. The GUS staining results of transgenic A. thaliana showed that the expression of GUS gene driven by BpSPL6 gene promoter had spatiotemporal specificity. Throughout the development of A. thaliana, the GUS gene driven by BpSPL6 gene promoter was expressed in euphylla, but the expression sites were different. As the leaf grows, it is first expressed at the tip of the leaf, then expands to the leaf vein and reaches the entire leaf, and the expression level gradually increases. At the same time, the GUS gene driven by BpSPL6 gene promoter is also expressed in the roots during vegetative growth. When transgenic A. thaliana was subjected to sodium chloride and mannitol stress, the expression level of GUS gene driven by BpSPL6 gene promoter decreased compared with control. Comparing the two stresses, the expression level of GUS gene changed more after being subjected to sodium chloride stress, indicating that the response to sodium chloride stress was stronger.  Conclusion  BpSPL6 gene may be involved in plant leaf and root development and response to salt and drought stress.
Abstract:
  Objective  Due to the frequent occurrence of forest pests and diseases, a large number of chemical pesticides are used for pest control which enter the water and pollute the water resources. Therefore, it is planned to establish a novel sample pretreatment method for on-site processing to detect pesticides in environmental water bodies.   Method  0.499 2 g of citric acid, 0.405 6 g of sodium dihydrogen phosphate, 0.218 4 g of sodium bicarbonate and 0.18 g of sodium caproate are weighed, ground and mixed evenly. The powder is compressed by a tablet machine into effervescent tablets for use. The polypropylene oil-absorbent cotton was cut into a cylinder with a height of 2 cm and a density of 60 mg/cm and packed into a filter column, which a novel homemade filter column was accomplished finally. The 10 mL sample was placed in a syringe and added with effervescent tablets. After the reaction was complete, it was filtered through a self-made filter column. After the filter column was eluted with 200 μL of acetonitrile, the filtrate was detected by gas chromatography-electron capture detector.   Result  Under the optimal conditions, the linearity was in the concentration ranges of 5−500 μg/L, with coefficients greater than 0.999 0. The limit of detection and limit of quantification were calculated based on 3 times signal-to-noise ratio and 10 times signal-to-noise ratio. The limit of detection and the limit of quantitation were in the range of 0.22−1.88 μg/L and 0.75−6.25 μg/L. The recovery rate was between 88.2−113.0%, the relative standard deviation was 0.8−6.1%, and the enrichment factor was between 65−108.  Conclusion  In this study, a new method named switchable hydrophilic solvent-based effervescent tablet assisted on-site dispersion liquid-liquid microextraction-gas chromatography was established to determine five pyrethroid pesticides in environmental waters. This method does not require the use of electrical equipment and can realize on-site pretreatment, which reduces the consumption of manpower and material resources and has broad application prospects.
Abstract:
  Objective  To reveal the influence rule of liberation cutting intensity on the medium and long term carbon sink of Korean pine forests by planting conifer and reserving broad-leaved tree(PCRBT), and to provide basis for the restoration of zonal climax vegetation broad-leaved Korean pine forest.  Method  The carbon storage (vegetation and soil), net primary productivity (NPP) and net annual carbon sequestration (ANCS) of the mid-term(35 years) Korean pine forests by PCRBT under the different liberation cutting(LC) intensity(control(C), Low-intensity LC(L)-1/7, moderate-intensity LC(M) -1/5, and high-intensity LC(H)-1/4(volume ratio)) were measured simultaneously by using the relative growth equation and carbon/nitrogen analysis method in temperate Xiaoxing’an Mountains of China, to reveal the law and mechanism of the effect of the liberation cutting on the carbon sink of the Korean Pine Forest.  Results  (1) The vegetation carbon storage (81.15 ± 3.63 ~ 85.48 ± 2.30 t/ha) of the Korean Pine Forests by PCRBT were significantly lower than that of control treatment (100.24 ± 1.10 t/ha) by 14.7% ~ 19.0% (P < 0.05) after liberation cutting 30 years, but the difference of vegetation carbon reserves was not significant among the low-, medium-, and high-intensity liberation cutting(because the carbon reserves of upper canopy broadleaf trees decreased with liberation cutting intensity (21.1% ~ 31.2%), while the carbon reserves of Korean pine under canopy increased by 39.0% ~ 107.4%). (2) The soil carbon storage (108.32 ± 6.27 ~ 121.42 ± 11.75 t/ha) of the Korean Pine Forests by PCRBT were similar to that of control (−8.4% ~ 2.7%, P > 0.05), however, the spatial distribution patterns of soil carbon storage were changed by the liberation cutting(on the horizontal distribution, the soil surface carbon storage decreased with increasing of liberation cutting intensity; on the vertical distribution, low-intensity and moderate-intensity liberation cutting made its vertical distribution changed from upper soil layer > middle soil layer ≈ lower soil layer in control forest to upper soil layer > middle soil layer > lower soil layer, or upper soil layer ≈ middle soil layer > lower soil layer). (3) The carbon storage of ecosystem (189.47 ± 5.16 ~ 218.44 ± 10.65 t/ha) of the Korean pine Forest by PCRBT has been recovered under low intensity LC (−5.3%, P > 0.05), but moderate-intensity and High-intensity LC still made them significantly lower than that of the control by 9.3% and 13.3% (P < 0.05), and the carbon storage distribution ratio of the ecosystem were slightly changed by all the three intensity LC treatments (the carbon storage ratio of vegetation was reduced by 3.06% ~ 4.57%). (4) The NPP(8.02 ± 0.79 ~ 9.51 ± 0.79 t/ha) and ANCS (3.72 ± 0.37 ~ 4.42 ± 0.37 t/ha) of the Korean pine forest under low intensity liberation cutting treatment have been restored (−11.5% and −9.7%, P > 0.05), while moderate-intensity and high-intensity liberation cutting still made them significantly lower than that of the control by 15.4% ~ 15.7% and 14.0% ~ 15.8% (P < 0.05), but there was no significant difference among the different liberation cutting intensity treatments (which because the net primary productivity and the annual net carbon sequestration of upper canopy broadleaf trees decreased by 20.8% ~ 25.6% and 19.3% ~ 24.5%, however, those of Korean pine under canopy increased by 0.90 ~ 1.12 t/ha and 0.43 ~ 0.52 t/ha, with the Liberation cutting intensities increasing).  Conclusion  Low-intensity liberation cutting have made the ecosystem carbon storage and annual net carbon sequestration amount of the Korean Pine forests by planting conifer and reserving broad-leaved tree restored after 30 years, while moderate-intensity and High-intensity liberation cutting made them significantly reduces 9.1% ~ 14.3% and 14.3% ~ 16.7% in the Xiaoxing’an Mountains. Therefore, from the perspective of maintaining forest carbon sink, it is more appropriate to adopt low intensity liberation cutting in the management practice of the secondary forest restoring zonal climax vegetation.
Abstract:
  Objective  To provide a theoretical basis for optimizing the intensive management technology in Populus tomentosa–Wheat agroforestry system under wide- and narrow-row spacing planting schemes, the distribution and morphological characteristics of fine root length density (FRLD) in this system were studied.  Method  In a four-year-old triploid P. tomentosa–Wheat agroforestry system under wide- and narrow-row spacing planting schemes, a soil coring method was adopted for roots sampling around three average standard trees after wheat harvest. The sampling locations were 75 cm away from tree lines for narrow row and 75 cm away from trees for tree row, while 100, 200, 300, and 400 cm away from tree lines for the wide row, sampling depth was 80 cm. A total of 288 root samples were obtained. All fine root samples were scanned, dried and weighed to obtain the distribution and morphological data in different depths and horizontal distances.  Result  Vertically, the fine roots of P. tomentosa and wheat were mainly concentrated in the shallow soil layer. The FRLD in 0–20 cm soil layer accounted for 68% and 45% of the total FRLD, respectively. The FRLD of decreased exponentially with depth for both P. tomentosa (R2 = 0.679 3, P < 0.05) and wheat (R2 = 0.922 9, P < 0.05). There was no significant difference in FRLD between the two species in the shallow soil layer (P > 0.05). However, in the deep soil layer, the FRLD of wheat was significantly higher than that of P. tomentosa (P < 0.05). Horizontally, Fine roots of P. tomentosa were mainly concentrated in narrow row and tree row, while fine roots of wheat were widely distributed in wide row. On a two–dimensional scale, two species had their own dense distribution zones of fine roots and did not interfere with each other. The fine root diameter of P. tomentosa was significantly higher than that of wheat, while its specific root length was significantly lower than that of wheat (P < 0.05).  Conclusion  In P. tomentosa–Wheat agroforestry system under wide- and narrow-row spacing planting schemes, the spatial distribution of the fine roots of P. tomentosa and wheat was separated, and the dense distribution area overlapped less. Also, in order to absorb soil resources more effectively and occupy a competitive advantage, wheat would produce more fine roots with higher absorption efficiency. The results can provide a theoretical basis for optimizing the intensive management technology in agroforestry system under this planting schemes.
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2021, (8): 1-2.  
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Abstract:
Forest Sciences
Abstract:
  Objective  This paper aims to develop a large number of specific SNP molecular markers in the whole genome of Pinus bungeana, and provide enough resources of molecular markers for key gene mapping, marker assisted selection and germplasm resource evaluation of P. bungeana.  Method  In this study, 52 P. bungeana resources from five populations were used as materials, and the genome of P. taeda was selected as reference genome. A large number of specific SNP sites were developed on polymorphic SLAF tags using specific length amplification fragment sequencing (SLAF-seq), and a batch of high-quality SNP sites were filtered out for genetic diversity analysis of different populations of P. bungeana.   Result  Through sequence comparative analysis, 23 597 049 SLAF tags were obtained, including 370 659 polymorphic SLAF tags and 1 291 290 SNPs of P. bungeana population were developed. Under the condition of missing rate was less than 20% and minor gene frequency (MAF) was greater than 5%, a total of 346 840 SNPs with high consistency were obtained, accounting for 26.9% of the total SNPs, including 9 SNP loci with mutation only in Jiufeng, Beijing (JF) population, 148 SNP loci with mutation only in Lantian, Shaanxi (LT) population, 425 SNP loci with mutation only in Maiji Mountain, Gansu (MJS) population, 1 466 SNP loci with mutation only in Wuzi Mountain, Shaanxi (WZS) population, 4 SNP loci with mutation only in Baiwa Mountain, Shanxi (BWS) population. Genetic diversities of 5 P. bungeana populations were analyzed based on 346 840 SNPs, and the results showed that there were significant differences in genetic diversity among different populations of P. bungeana, among which the level of genetic diversity was relatively high in MJS and WZS population, and relatively low in JF population.   Conclusion  The results showed that SLAF-seq technology can be used to develop a large number of SNP markers in the whole genome, and the developed SNP markers showed abundant genetic polymorphisms in different populations of P. bungeana. The results of this study lay a foundation for the identification of germplasm resources, QTL mapping, construction of genetic linkage map and association analysis of important traits of P. bungeana, and are of great significance for the protection of germplasm resources and molecular marker assisted breeding of P. bungeana in the future.
Abstract:
  Objective  Hybrid sweetgum is an important timber and ornamental tree resources in China, but its genetic transformation system has not been established yet. Establishing genetic transformation system of hybrid sweetgum provides a useful approach for trait improvement and allows us to conduct a functional identification of gene in hybrid sweetgum.   Method  Based on the efficient somatic embryogenesis of hybrid sweetgum, the embryogenic calluses were transformed by Agrobacterium tumefaciens-mediated genetic transformation. Factors influencing transformation were studied by orthogonal experiment, including hygromycin selective pressure, concentration of Agrobacterium, infection time, co-culture time and co-culture temperature.  Result  Results showed that the minimum lethal concentration of hygromycin to embryogenic callus was 10 mg/L. The number of Gus positive spots was highest when bacterium solution (OD600) was 0.8, co-culture time was 3 d, infection time was 10 min, co-culture temperature was 25 ℃. The most transgenic positive resistant calluses were obtained when bacterium solution (OD600) was 0.2, co-culture time was 2 d, infection time was 10 min, co-culture temperature was 23 ℃. And the optimal treatment combination was 0.2 bacterium solution (OD600), 2 d co-culture time, 20 min infection time, 23 ℃ co-culture temperature.   Conclusion  A total of 210 positive transgenic callus were obtained by molecular identification. The genetic transformation system was established, which provides more feasible foundation for the transformation of broadleaf tree callus.
Abstract:
  Objective  This paper aims to reveal the biomass allocation and allometric relationships from different families, and to analyze their ontogenetic law and adaptive strategy of seedlings.  Method  The growth and biomass indexes of 310 Pinus yunnanensis seedlings from 10 families were investigated. One-way ANOVA was used to compare the differences in biomass and biomass allocation of seedlings from different families, and the allometric relationship was analyzed by standardized major axis analysis.  Result  (1) The biomass accumulation and allocation were different among varied families, the biomass allocation in each organ was ordered by leaf > stem > root, the biomass allocation of seedlings was constrained by its individual size, and the smaller the individual size was, the larger the leaf biomass ratio was, while the larger the individual size was, the more the stem biomass ratio was. (2) The allometric growth relationships within the plant organ biomass and organ biomass to individual size were quite discrepant, but the growth relationships were isometric overall. (3) The biomass pair aboveground and root biomass, stem and root biomass of seedlings exhibited a common allometric scaling exponent index of 1.054 and 1.209, respectively. The seedlings of different families had both isometric and allometric relationships.  Conclusion  There is no consistency allometric growth relationship among different families, but it represents the growth and adaptation strategies of seedlings.
Abstract:
  Objective  Different crown prediction methods were used to predict varied crown components (east, west, south, north crown width and east-west crown width, south-north crown width, average crown width) of young spruce fir, and the prediction accuracy was compared in order to provide a theoretical basis for the tending of spruce fir management.  Method  The measured data of different crown components in permanent spruce fir sample plots was got from three 1 ha sample plots on Jingouling Forest Farm of northeastern China in 2013, the logistic model was chosen as base model and the ordinary least square method was used to fit crown radii of east, west, south, north and crown width of east-west, south-north, and mean direction. 1/D, 1/D0.5, and 1/D2 were used as weight function to eliminate the heteroscedasticity of model residuals. The unweighted nonlinear seemingly unrelated regression method, weighted nonlinear seemingly unrelated regression method, quantile regression method, and ordinary least square method were applied to develop different crown component prediction model.  Result  The fitting results indicated that, quantile regression model had the lowest fitting accuracy, compared with quantile regression, weighted nonlinear seemingly unrelated regression and weighted ordinary least square regression had nearly same fitting effectiveness. The accuracy order arrangement was weighted NSUR ≈ weighted OLS > OLS > QR, 1/D2 was the best choice to eliminate heteroscedasticity by residuals plot.  Conclusion  In this paper, the fitting effect of nonlinear quantile regression model was not necessarily better than that of nonlinear least square method, the weighted nonlinear seemingly unrelated regression model (1/D2 as weight function) developed in this essay can provide some theory basis for different crown components of young spruce fir.
Abstract:
  Objective  In this paper, taking the coniferous and broadleaved mixed forest at different development stages in Jiaohe, Jilin Province of northeastern China as research object, the interannual variation of kernel density estimation curve of seedling density was compared and analyzed. The relative effects of marginal changes of soil factors and distribution changes of soil factors on the dynamics of seedling density distribution were discussed.  Method  Seedling investigation sample plots were systematically arranged in 420 m × 520 m half-matured forest (HF) sample plots and 500 m × 840 m mature forest (MF) sample plots. Quantile regression and counterfactual decomposition were used to test the marginal effects of environmental factors on seedling density at different quantile levels, and then to identify the leading factors resulting in the unequal change of seedling density.  Result  The kernel density estimation curve of seedling density showed a positive skewed distribution with peak value shifting to the left and long tail extending to the right. At the high quantile of θ = 0.90, the change value of seedling density was −5.9 in HF sample plots and −2.6 in MF sample plots. The change value of seedling density in HF sample plot was 5.8 when θ = 0.75, and that in MF sample plot was 2 when θ = 0.50 and θ = 0.75. The greater change of seedling density at high quantile reflects the inequality of probability distribution of the right single tail. The relative effects of coefficient effect and covariant effect on seedling density distribution were different in varied estimated quantiles. The coefficient effect in HF sample plots had a high explanation on all estimated quantiles; in MF sample plots, the covariant effect had 89% explanation for the change of seedling density at θ = 0.50 quantile. In other estimated quantiles, the explanation of coefficient effect was higher. Therefore, the relative effect of distribution of soil factors on the distribution of seedling density was greater, and the marginal change of soil factors was the main factor leading to unequal change of seedling density. Most of the changes in the distribution of available nitrogen, available phosphorus and available potassium in soil explained less than 30% of the changes in seedling density at each estimated quantile, while soil water content and soil pH had a relatively greater effect on the change of seedling density.  Conclusion  The interannual variation of seedling density is unequal in different quantiles, especially in the high quantile. The marginal change of soil factors and the distribution of soil factors determine the survival dynamics of seedlings.
Abstract:
  Objective  In this study, soil quality index (SQI) was used to evaluate the effects of different mixed modes on soil fertility quality in Larix principis-rupprechtii forests, in order to provide theoretical basis for proper management and soil fertility recovery.  Method  The pure Larix principis-rupprechtii stands (LP), mixed Larix principis-rupprechtii and Betula platyphylla stands (BL), and mixed Larix principis-rupprechtii and Pinus sylvestris var. mongolica stands (ML) were selected as the research objects in Saihanba Mechanical Forest Farm of Hebei Province, northern China. The soils of 0−20 cm soil depths were collected and analyzed to investigate the soil physicochemical and biological properties. SQI was used to evaluate soil fertility quality. SQI was determined in three steps by selecting a minimum data set (MDS) through principal component analysis, scoring the MDS indicators using non-linear scoring functions, and integrating the indicator scores into a SQI using the weighted additive equation.  Result  There were different degrees of differences in soil physicochemical and biological properties among different mixed modes. Compared with LP, the soil physicochemical and biological properties of BL were significantly improved. The soil physicochemical conditions in ML were worse than those in LP. And there were no obvious differences in soil biological properties in ML and LP. The MDS consisted of soil microbial biomass nitrogen, total phosphorus, and ammonia nitrogen among 17 soil fertility quality indicators. There were significant differences in the SQI among three mixed modes, which were showed as: BL (0.59) > LP (0.47) > ML (0.39).  Conclusion  The soil fertility quality differed significantly among varied mixed modes. The mixed Larix principis-rupprechtii and Betula platyphylla stands in Saihanba Mechanical Forest Farm can improve soil fertility. Soil fertility quality evaluation based on SQI by indexing approach can provide the basis for evaluating forest soil quality of other species and regions.
Abstract:
  Objective  The hydrological effects of litter layer and soil layer of Larix kaempferi plantation under different management models in subtropical regions were studied and compared, and the correlation between hydrological performance of the two was explored to provide scientific basis for regional forest hydrological cycle and forest health management.  Method  Taking three typical management models of Larix kaempferi plantation (Larix kaempferi-Sassafras tzumu mixed management model, Larix kaempferi-Liriodendron chinense mixed management model and Larix kaempferi pure forest management model) in Changlinggang State-Owned Forest Farm of Jianshi County as the research objects, and the hydrological effects of litter layer and soil layer were studied by means of sample plot observation method, indoor immersion method, cutting ring method and double ring method, and the regression analysis and bivariate correlation analysis were used to fit and analyze the hydrological effects.  Result  (1) There were significant differences in the stratification changes of litter thickness and volume under different management models (P < 0.05); the thickness and volume of semi-decomposed layer in mixed forest management model were significantly higher than those in un-decomposed layer, but the opposite was true in pure forest management mode. (2) The change law of water holding capacity and water absorption rate of litter with soaking time in different management models was basically consistent. There was a logarithmic regression relationship between litter water holding capacity and soaking time, and a power function regression relationship between litter water absorption rate and soaking time. (3) The soil physical properties and infiltration performance of mixed forest were better than that of pure forest, and the difference was significant (P < 0.05); the relationship between soil infiltration rate and infiltration time was power function regression. (4) There was a certain correlation between the hydrological effects of litter layer and soil layer in different management models. Except for soil bulk density, soil hydrological indexes were positively correlated with hydrological indexes of semi-decomposed layer of litter, and negatively correlated with hydrological indexes of un-decomposed layer of litter; maximum soil water holding capacity, total porosity, initial infiltration rate, steady infiltration rate were positively correlated with thickness of litter, maximum water holding capacity and maximum water absorption rate of semi-decomposed layer.  Conclusion  Generally, the hydrological properties of litter layer and soil layer of mixed management model were better than that of pure forest management model. It is suggested that the influence of tree species composition and configuration mode should be fully considered in forest management, and the near-natural broadleaved transformation of pure coniferous forest should be accelerated to strengthen the hydrological function and healthy management of regional forest.
Abstract:
  Objective  Our objective was to explore the mechanism of the effects of thinning on non-structural carbon (NSC), carbon (C), nitrogen (N) and phosphorus (P) stoichiometry of Pinus yunnanensis.  Method  The middle-aged P. yunnanensis forests were chosen in the Baima River forest area of Yongren County, Yunnan Province of southwestern China, and two experimental sample plots of thinning (thinning intensity of 35.4%) and control were set up to analyze the effects of thinning on NSC and CNP stoichiometric characteristics of P. yunnanensis forests.  Result  (1) Tending thinning significantly affected the NSC content of needles and branches of P. yunnanensis (P < 0.01), whereas no significant difference on roots was observed. In addition, the NSC content of branch increased by 9.30%, while the NSC content in needles decreased by 3.57%. (2) Thinning had a significant effect on C content of P. yunnanensis branch, P content in needles and stems (P < 0.05), and a highly significant effect on N content in needles (P < 0.01), however, no significant effect was observed on C, N and P content in roots. After thinning, the C content of P. yunnanensis branch increased by 12.93%; the N content in needles increased by 18.04%, and the P content in needles and stems decreased by 27.78% and 55.56%, respectively. (3) The NSC, CNP stoichiometric characteristics showed significant differences among P. yunnanensis organs (P < 0.05). Correlation analysis showed that the P content in needles and roots was significantly positively correlated with soluble sugar content (P < 0.05), while C content in needles was significantly negatively correlated with soluble sugar content (P < 0.05).  Conclusion  Thinning promots the accumulation of NSC content in stem, branch and root and C content in each organ, whereas needle NSC and P content decreased in each organ, furthermore, distribution pattern of C, N and P in each organ was affected; the growth of P. yunnanensis plantation in this area was limited by N to some extent, and appropriate application of N fertilizer will promote the improvement of stand quality.
Abstract:
  Objective  Potassium (K) is a vital element to sustain plant growth and high water-use efficiency, especially in the current context of increasing aridification. However, previous studies on plant K have mostly been conducted at local scale, and it is still unclear that what difference exists in the spatial patterns and controlling factors of leaf K content among different herb functional groups across large scale.  Method  Based on an analysis of 685 herbaceous plants across 158 sampling sites in China, this study aims to reveal the spatial patterns of leaf K content among different herb functional groups, and further quantify the relationship of leaf K with climate or soil nutrients.  Result  Our results showed that: (1) herb leaf K content across China increased linearly with latitude, but decreased with longitude. Its spatial patterns were different among varied functional groups. (2) These patterns of leaf K were mainly driven by humid index and soil total nitrogen. (3) The impacting factors of the spatial patterns were different among varied functional groups. Leaf K in annual herb was significantly affected by both humid index and soil total nitrogen, while it was only influenced by soil total nitrogen for perennial herb. Leaf K in herbs with low K use efficiency was mainly affected by humid index and soil total nitrogen, but it was impacted by soil total nitrogen and total phosphorus for herbs with high K use efficiency. The main impacting factor of leaf K in Asteraceae and Cyperaceae herbs was soil total nitrogen, but humid index for Poaceae herbs.  Conclusion  This study is the first to systematically compare and reveal the difference in the spatial patterns and key controlling factors of leaf K among different herb functional groups across China. These results have important implications for understanding the adaptive mechanisms of plant functional groups and the dynamics of plant community composition with increasing global aridification.
Abstract:
  Objective  This paper aims to screen out the pioneer plants that can adapt to the habitat characteristics such as large slope angle, barrenness and aridity of coal gangue piles in North China, and build a stable vegetation community to solve the environmental problems such as soil erosion, re-ignition and dust emission caused by the lack of vegetation cover in acidic coal gangue piles.  Method  14 dominant species of herbaceous plants commonly used in land reclamation and those native to North China were analyzed and compared by field experiments using life cycle, cover, significance value and ecological position width as indicators.  Result  The artificially introduced Medicago sativa and Astragalus dahuricus can adapt well to the habitat of the coal gangue pile, and maintain an advantageous position in the vegetation community on the reclaimed slope, with a life cycle of more than 7 months, the maximum sub-coverage of 33.93% and 17.59%, but from June to September, the cover decreased significantly. Among the native species, Artemisia capillaris had a wider ecological position, with the highest cover in July and September, and the maximum sub-coverage of 12.67, can make up for the lack of Medicago sativa and Astragalus dahuricus in the summer cover is lower.  Conclusion  The above three herbaceous plants can be used as the pioneer species for the future vegetation restoration in the coal gangue piles.
Forestry Engineering
Abstract:
  Objective  The objective of this research was to investigate the difference of medium density fiberboard (MDF) cutting characteristics between spherical cone grit and pentagonal pyramid grit and study the action mechanism of cutting edges on fibrous material removal in sanding process. This research is going to provide some theory basis to fulfill highly efficient sanding.  Method  Spherical cone grit and pentagonal pyramid grit were used to conduct the cutting experiments through a wedge-style scratching method. High-speed camera, three-dimensional dynamometer and 3D profiler were applied to record and measure the dynamic cutting process, the cutting force variation and the sanded surface morphological profile.  Result  Spherical cone grit caused more material pile-up on both sides of the groove, where the initial surface integrity was better. For nearly the same groove volume, more chips formed in the pentagonal pyramid grit cutting, where the relative moment of chip formation was earlier for a single scratch with more evident chip flowing from the two rake faces. For a single scratch, the pentagonal pyramid grit presented less time to reach the peak value of tangential cutting force. The two kinds of abrasive grits when cutting MDF showed a quadratic increasing trend between cutting force and cutting depth. And the force ratio of the pentagonal pyramid grit was greater. There was a quadratic variation that first decreased and then increased between the specific grinding energy and the groove volume for the two kinds of abrasive grits. And there existed a turning point that was the critical groove volume (a critical cutting depth). When the groove volume was basically the same, the actual specific energy of spherical cone grit was greater than that of the pentagonal pyramid grit.  Conclusion  The pentagonal pyramid grit which was with evident cutting edges presented better cutting performances, specifically higher material removal rate and energy utilization rate, which shows that cutting edge plays a key role in removing fibrous material during sanding processes.
Abstract:
  Objective  The performance effect of Guzheng is not only related to the skill of performer, but also closely related to the structure of Guzheng itself. Among them, the resonance panel receives the vibration of string and causes the resonant sound, which is a crucial part of the sound process of Guzheng. In this study, the acoustic vibration performance of Guzheng resonance panel with whole board structure was studied by different analysis methods.   Method  The experimental modal analysis of the resonant panel was carried out by ZSDASP signal acquisition and analysis software, and the characteristics and laws of the resonance frequencies of each order and the corresponding mode shapes were obtained. A three-dimensional model of the resonance panel of the whole board structure was established, and the computational modal analysis was carried out to verify the feasibility of the computational modal analysis applied in this study.   Result  Through modal analysis experiment and computational modal analysis, it was found that with the increase of vibration order, the mode shapes of the resonant panel of the whole board structure tended to be more complicated, and the corresponding resonance frequency gradually increased. In the modal experiment results, the resonance frequencies of (0, n), (1, n) and (2, n) orders were easier to identify; the mode shapes corresponding to the (0, n) order were relatively clear and easy to identify, but the mode shapes corresponding to the lower orders of (1, n) and (2, n) were not obvious. The modes corresponding to each frequency that can be identified by the computational modal were (1, n) and (2, n), which were missing (0, n) compared with the experimental modal results. But the results obtained by computational modal analysis were more continuous, and all orders of (1, n) and (2, n) can be identified. Several orders were not obvious enough in experimental modal analysis.  Conclusion  The results of computational modal analysis are compared with the experimental modal results, and it is concluded that the computational modal analysis is feasible to be applied to the vibration modal research of the resonant panel of the whole board structure of Guzheng.
Abstract:
  Objective  By analyzing the influence of thickness and decorative materials on very volatile organic compounds (VVOC) and odor intensity of wood-based panels, the released characteristics were explored.  Method  Melamine-impregnated paper finished particleboard, polyvinyl chloride finished particleboard and particleboard with different thickness were selected as experimental subjects. VVOC and odor characteristic compounds released from these particleboards were analyzed by gas chromatography-mass spectrometry/olfactory.  Result  In this experiment, the types of VVOC of particleboard (PB), melamine-impregnated paper finished particleboard (MI-PB), and polyvinyl chloride finished particleboard (PVC-PB) were 9, 10 and 8, respectively. The released concentrations of TVVOC were as follows: PB > MI-PB > PVC-PB, 18 mm > 8 mm. TVVOC emission concentration of particleboard with different decorative materials was affected by the thickness to different degrees, with PB being the most affected and MI-PB being the least. Under different thicknesses and different finishes, the released concentration and odor intensity of each odor characteristic compound were different, and the odor intensity was related to the released concentration and odor threshold, different compounds did not conform to the changing rule of “higher concentration leads to higher odor intensity”. The overall odor characteristics of the decorative particleboard were mainly determined by the special fragrance and sweet fragrance, and the pungent odor as the basic characteristic odor plays an auxiliary role in the formation of overall odor. The main components of VVOC released from decorative particleboard were alcohols and ketones. The characteristic compounds with higher odor intensity were alcohols, ketones, ethers and esters. The types and mass concentration of VVOC were increased with the increase of thickness, and the odor characteristic compounds and odor intensity were increased accordingly.  Conclusion  Decorative treatment can reduce the released species and content to a certain extent, and in this experiment, PVC as a decorative material plays a better inhibiting role on VVOC and odor intensity of particleboard than melamine-impregnated paper.
Abstract:
  Objective  Replacing the web of I-shaped timber beam with steel can solve the problems of web shear failure and low bending stiffness of bare timber beam. This helps to reduce the component size and increase its application in large-span buildings.  Method  The steel-timber composite (STC) beam was prepared by connecting two timber slabs on the H-shaped steel flanges with bolts. The influence of different bolt spacing and shear-span ratio on the structural behavior (failure modes, stiffness and load capacity) of STC beams were studied. Three-point bending tests were carried out on 11 STC beams. Four push-out tests were carried out to investigate steel-timber interface slip.  Result  The bending stiffness of the STC beams was 201% higher than that of the rectangular timber beam with the same section size. The steel upper flange was prone to buckle by concentrate load. Increasing the shear-span ratio, the failure converts from brittle to ductile, the initial failure transforms from top timber slab to bottom. Increasing the shear-span ratio or decreasing the bolt spacing, the bending stiffness was declined, the ductility coefficient was improved and the peak load decreased by more than 15%. The formulations of yield load and mid-span deflection considering interface slip between steel and timber were proposed, the error of most specimens was less than 10% between calculated and experimental results. In addition, referencing material properties and push-out test, the finite element models of STC beams were established. The errors between simulated and experimental values of bending stiffness and yield load were basically within 10%.  Conclusion  Steel used as the web can significantly improve the bending stiffness of beams and prevent shear failure of webs. Considering the interface slip, the theoretical calculation and simulation results of flexural performance of STC beams are accurate.
Reviews
Abstract:
Biomass is an important information in the study of forestry and ecological applications, and remote sensing technology of aboveground biomass estimation in forest ecosystems has attracted intensive attention of the international scholars. Reviewing and discussing different data sources and estimation methods can provide guidance for estimation of forest aboveground biomass. This study discussed the application of single sensor remote sensing data, including optical remote sensing, synthetic aperture radar and LiDAR data in forest biomass estimation, and the advantages of using multi-sources remote sensing data to estimate forest biomass. Then we discussed the traditional analysis methods and machine learning methods (decision tree regression, k-nearest neighbor, artificial neural network, support vector regression, maximum entropy) used for estimating forest biomass. Multi-source remote sensing data integration can combine the advantages of different data and provide rich characteristic information for forest aboveground biomass estimation. Combining machine learning methods is a development trend to improve the accuracy of forest aboveground biomass estimation.

Establishment Time:1979

CN 11-1932/S

ISSN 1000-1522

Supervisor:Sinopec Research Institute of Petroleum Engineering

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