Objective: The objective was to explore the differences of soil respiration and its components among different levels of nitrogen addition of the natural forest of Pinus tabulaeformis under long-term nitrogen enrichment, to reveal the main influencing factors of the changes in the respiration of soil components, and to provide a scientific basis for evaluating the effect of long-term nitrogen application on soil respiration in regional forests. Method: We conducted a 10-year nitrogen addition experiment (2009-2018) in a P. tabulaeformis forest in Taiyue Mountain, Shanxi Province, with four levels of nitrogen addition including control (CK, 0 kg N·hm^-2 a^-1), low nitrogen (LN, 50 kg N·hm^-2 a^-1), medium nitrogen (100 kg N·hm^-2a^-1), and high nitrogen (HN, 150 kg N·hm^-2 a^-1). Soil respiration and its components were measured monthly in growing seasons from 2016-2018. Result: Mean annual soil respiration rate was significantly decreased by 21.9%, 27.3%, and 29.1%; and mean annual heterotrophic respiration rate was significantly reduced by 21.8%, 36.6%, 31.4% under LN, MN and HN, respectively, compared with the control. Long-term nitrogen addition had no significant effect on soil autotrophic respiration rate. Meanwhile, soil pH and soil microbial biomass carbon were significantly decreased by 0.07, 0.37, 0.78 units and 11.3%, 14.5%, 14.7% under LN, MN and HN, respectively relative to the control. However, soil organic carbon, total nitrogen and fine root biomass were not altered by nitrogen enrichment. There was a significant linear relationship between heterotrophic respiration and soil microbial biomass carbon; autotrophic respiration also exhibited a significant linear correlation with fine root biomass. The long-term nitrogen addition significantly increased temperature sensitivity(Q₁₀) of soil autotrophic respiration (CK=2.19, LN=2.90, MN=2.86, HN=2.34), but decreased the Q₁₀ values of soil heterotrophic respiration (CK=2.72, LN=2.23, MN=2.12, HN=2.27). Soil respiration were not correlated with soil moisture (P>0.05). In addition, two-factor models combining soil temperature and soil moisture explained 28.7%-42.0% (P < 0.05) and 64.9%-78.1% (P < 0.001) of the autotrophic respiration and heterotrophic respiration, respectively. Conclusion: Long-term nitrogen addition reduced soil respiration by the nitrogen-induced decrease in the heterotrophic respiration, but had no significant effect on autotrophic respiration rate. In addition, changes in respiratory substrates were the main factors for the inconsistent effects of chronic nitrogen application on the Q₁₀ values of autotrophic and heterotrophic respiration. Our study highlights that fine root biomass and respiration substrate should be incorporated into future models when accurately predicting chronic nitrogen addition effect on soil respiration and its components.

Objective: It's the first time to report the characteristics of 7-year-old Castanopsis fargesii natural forest which was converted from Eucalyptus dunnii plantation that suffered from successive freezing damage in Yong'an, Fujian Province, aiming to provide a scientific basis for revealing the basic conditions for the conversion of plantations into natural broad-leaved forests in mid-subtropical zone, the vegetation control of plantation, the protection of natural broad-leaved forest and the development of native hardwood forest. Method: 3 sample plots in size of 20 m×20 m were set in the natural forest of C. fargesii which was converted from E. dunning plantation in Yong'an, Fujian Province, and each plot was divided into four 10 m×10 m quadrats. The arbor layer of each quadrat was investigated and one representative quadrat in each plot was selected for shrub layer investigation. At the same time, a small quadrat of 4 m×4 m was set in the center of each plot for the investigation of the herb layer. The stand characteristics such as tree species composition, diversity of the arbor layer and shrub layer and stand growth were analyzed by using important values, commonly used diversity indices and main stand description factor. Results: The mean DBH, mean height, density and volume of the 7-year-old C. fargesii natural forest which was converted from E. dunnii plantation were 5.1 cm, 6.8 m, 6 350 stems·hm^-2 and 47.70 m³·hm^-2, respectively. The ratio of height to diameter was between 43 and 393, and the average was 146. Both the diameter and tree height structure showed the characteristics of heterogeneous forest. The proportions of regenerated seedlings and sprouts were 84.78% and 15.22%, respectively. E.dunnii was in the form of dead standing tree or down-timber, and the density of dead standing tree was 550 stems·hm^-2. There were 51 tree species in the arbor layer, and the Shannon-Wiener index, evenness index and dominance index were 4.20, 0.74, and 0.11, respectively. The number of arbor and shrub species in the arbor layer were 38 and 13, and the importance values were 87.32% and 12.78%, respectively. There were 30 evergreen and 21 deciduous tree species in the arbor layer, with the importance values of 57.93% and 42.07%; and the number of trees and tree species of broad-leaved evergreen were more than that of deciduous broad-leaf trees. C. fargesii was the dominant species in the arbor layer, and its relative abundance, relative frequency, relative dominance and importance value were the largest. There were 21 tree species in the shrub layer. The Shannon-Wiener index, evenness index and dominance index were 3.68, 0.84, and 0.10, respectively. The number of arbor and shrub species were 15 and 6, respectively, and the proportion of arbor species (47.68%) was less than shrub species (52.32%), but its importance value (53.91%) was higher than that of shrub species (46.09%). In the shrub layer, not only the number of tree species but also the relative abundance, relative frequency, relative dominance and importance value of evergreen tree species were higher than that of deciduous tree species. Among all the tree species in the shrub layer, the relative abundance, relative frequency, relative dominance and importancevalue of the Eurya loquaiana were the largest. Compared with the C. fargesii forest by artificial measures promoting natural regeneration (AMPR) of similar ages, there were no differences in characteristics of the 7-year-old C. fargesii between the natural forest and those of similar ages. It belongs to a relatively typical subtropical natural broad-leaved forest in the young stage. Both in arbor and shrub layer, there were many precious or high value timber tree species. Conclusion: The E. dunnii plantation has been successfully converted into 7-year-old C. fargesii natural forest with rich tree species diversity and distinct characteristics of heterogeneous forest. This C. fargesii natural forest has a high canopy density, tree number density, ratio of height to diameter and stand volume. The stand characteristics of the 7-year-old C. fargesii natural forest were no longer essentially different from those of C. fargesii forest byartificial measures promoting natural regeneration atsimilar age. It was a relatively typical subtropical natural broad-leaved forest in the young period and a typical case of successful conversion of the subtropical plantation into a natural broad-leaved forest.

Objective: The changes of metabolites and metabolic pathway in leaves of two Nitraria species under salt stress were studied in order to reveal the metabolic response mechanism of Nitraria to salt stress, which could provide the basic theory basis for effectively improving the sustainable biological improvement and adaptability of Nitraria to saline-alkali soil. Method: The seedlings of N.tangutorum And N.sibirica. were treated with 300 mmol·L^-1 NaCl with distilled water as the control. The effects of salt stress on metabolites and their metabolic pathways in leaves of two Nitraria species were analyzed by GC-TOF-MS metabonomics. Result: 1) There were 11 differentially expressed metabolites in the leaves of N.tangutorum under salt stress, 8 of which were significantly up-regulated, including 1 fatty acid, 5 organic acids, 1 alcohol and 1 base derivative, while there were 108 differentially expressed metabolites in the leaves of N.sibirica, 106 of which were significantly up-regulated, including 51 amino acids, 22 sugars, 11 fatty acids and 8 organic acid, 7 alcohols, 5 alkaloids and 2 vitamins. 2) Through KEGG annotation, the differentially expressed metabolites of N.tangutorum can be enriched into six metabolic pathways, and the key pathways that have the highest correlation with the difference of metabolites are sulfur metabolism, TCA cycle and dicarboxylic acid cycle through topological analysis, while the differentially expressed metabolites of N.sibirica can be enriched into 46 metabolic pathways, of which up to 13 are amino acid metabolism, and the key pathways arevaline, leucine and isoleucine biosynthesis, C5-Branched dibasic acid metabolism and pantothenate and CoA biosynthesis. Conclusion: The two Nitraria species have different metabolic response mechanisms to salt stress. N.tangutorum responds to salt stress through changes of 11 metabolites that are mainly composed of organic acids, and responds to salt stress by strengthening six metabolic pathways mainly composed of sulfur metabolism. N.sibirica responds to salt stress through changes of 108 metabolites, which mainly include amino acid, sugar and fatty acid, and also responds to salt stress by strengthening 46 metabolic pathways, mainly amino acid metabolism. The metabolites involved in the regulation of salt stress in N.sibirica have more species, more ways and more significant metabolic response to salt stress than those in N.tangutorum.

Objective: Genetic improvement using somatic embryogenesis of larch can improve the environmental adaptability and the wood yield of larch. Exogenous hormones are an important factor affecting the somatic embryogenesis of larch, so we explored the effects of exogenous hormones on the different stages of somatic embryogenesis of Larix kaempferi, in order to improve the quality of embryos obtained through somatic embryogenesis and to accelerate the genetic transformation of larch. Method: The delay phase, logarithmic phase and plateau phase of the growth curve were first determined. Then, according to the growth curve, orthogonal design was used to investigate the proliferation and somatic embryogenesis of proembryogenic masses at 2, 4-D 0.15, 0.30, 0.50 mg·L^-1, 6-BA 0, 0.15, 0.30 mg·L^-1 and ABA 0, 0.50, 1.00 mg·L^-1 concentrations on day 7, 14 and 21, factorial design was used to investigate the suspension cell growth and somatic embryogenesis at 2, 4-D 0.15, 0.30, 0.50 mg·L^-1 and 6-BA 0, 0.15, 0.30 mg·L^-1 concentrations on day 7, 14 and 21, and the optimum hormone concentrations of the two cultures were determined. Finally, the effects of GA₃ or IAA on somatic embryogenesis were studied using a somatic embryogenic induction medium without GA₃ or IAA as the control. Result: The results showed that day 7, 14 and 21 were in the delay phase, logarithmic phase and plateau phase of proembryogenic mass proliferation and suspension cell growth, respectively. Then, the effects of 2, 4-D, 6-BA, and ABA on proembryogenic mass proliferation were proved to be obvious(P < 0.05), and the optimal hormone combination comprised 2, 4-D 0.15 mg·L^-1 and ABA 0.50 mg·L^-1. The effects of 2, 4-D and 6-BA on suspension cell growth was dramatic(P < 0.05), and the optimal hormone combination comprised 2, 4-D 0.15 mg·L^-1 and 6-BA 0.15 mg·L^-1. Finally, we found that the effects of GA₃ and IAA on somatic embryogenesis were all significant(P < 0.05), and the mature somatic embryo number increased significantly when 10-20 mg·L^-1 GA₃ or IAA was added, whereas the higher concentrations of GA₃ or IAA significantly inhibited it. Conclusion: Exogenous hormones can effectively regulate the cell proliferation. The optimal hormone combination for proembryogenic mass proliferation comprised 2, 4-D 0.15 mg·L^-1 and ABA 0.50 mg·L^-1, and the optimal hormone combination for suspension cell growth comprised 2, 4-D 0.15 mg·L^-1 and 6-BA 0.15 mg·L^-1. In addition, 10-20 mg·L^-1 GA₃ or IAA could significantly increase the number of mature cotyledon embryos of Larix kaempferi. The results laid a foundation for large-scale propagation and genetic modification of larch.

Objective: In this study, we identified xylem development-related genes in differentiating xylem of Larix kaempferi and built a gene co-expression network among hub genes and xylem development-related genes, aiming to provide reference for wood formation-related studies in L. kaempferi in future. Method: Illumia-seq and SMRT-seq were used to sequence xylem, phloem and needles of L. kaempferi; The differential expressed genes(DEGs) between xylem and phloem and between xylem and needles were identified by DEseq2 package in R software. The specifically expressed genes in differentiating xylem were obtained by comparing DEGs in the two parallel groups. The functions of these xylem-specific genes were predicted using GO, KEGG and BLASTN method. WGCNA method was used to build a co-expression network. Result: We obtained 2 596 genes in total that were specifically up or down regulated in the differentiating xylem of L. kaempferi; GO analysis showed that these genes were mainly enriched in metabolic process, cellular process, localization, membrane, cell, cell part, catalytic activity, binding and transporter activity. KEGG analysis showed that these genes were significantly enriched in starch and sucrose metabolism, flavonoid biosynthesis and metabolic pathways. 38 and 196 genes were enriched in phenylpropanoid biosynthesis and starch and sucrose metabolism pathway, respectively; In the differentiating xylem of L. kaempferi, lignin formation-related genes were identified including PAL4, CCR1, C4H, HCT, COMT1, PER12, PER52, CYP98A3, LAC12 and LAC17, and cellulose and hemicellulose formation-related genes were identified including DEC, CEL1, Csl, CTL2 and SPS3. All 2 596 up or down regulated genes were analysed by WGCNA method, 17 hub genes having close relationship with wood formation-related genes were obtained. Conclusion: Xylem development-related genes in Larix kaempferi participate in biological processes of wood formation such as galactomannan biosynthesis, xyloglucan biosynthesis, microfibrils formation, fiber biosynthesis in cell wall, secondary cell wall formation, fiber elongation, carbon flux to lignins, biosynthesis and degradation of lignin, monolignol polymerization, monolignol methylation and programmed cell death; the 17 hub genes in gene co-expression network are candidates for function exploration during wood formation in future.

Objective: Plant SKOR(Stelar K⁺ outward rectifier) is a typical outwardly rectifying Shaker type potassium(K⁺) channel, mediated long-distance K⁺ transport from roots to shoots. The objectives of this study were to isolate a K⁺ channel gene PdbSKOR from the hybrid of Populus davidiana × P.bolleana, to characterize the tissue-specific expression patterns of PdbSKOR gene and responses to K⁺ depletion, K⁺ excess, drought and low temperature treatments, and to determine electrophysiological function. Method: By carrying out homology-based cloning, a putative K⁺ channel gene PdbSKOR was characterized and cloned from P.davidiana × P.bolleana. The details of PdbSKOR gene and encoded protein were analyzed. MEGA7.0 software was used to construct a phylogenetic tree by multiple alignment of 14 SKOR proteins from different genera and families, including the hybrid of P.davidiana×P.bolleana. Expression profiles of PdbSKOR and responses to K⁺ depletion, K⁺ excess(60 mmol·L^-1 KCl), drought(15% PEG6000) and low temperature(4℃) treatments, especially in the roots, were analyzed using quantitative real-time RT-PCR(qRT-PCR). The electrophysiological function of PdbSKOR was preliminarily determined using patch clamping. Result: The K⁺ channel gene PdbSKOR(GenBank No. MT335814) was cloned from hybrid of P.davidiana × P.bolleana. PdbSKOR possessed the functional domains of 6 ion trans-membrane domains(S1-S6), cyclic nucleotide binding domain, ankyrin domain and KHA dimerisation domain, which belonging to the classic plant potassium channels. The amino acid sequences of SKOR proteins from 14 woody plants shared an overall identity of 81.09%, and the highest identity(96%) was observed in the S6 transmembrane region. The phylogenetic tree showed that SKOR homologs from different families and genera are quite different during evolution, while those from the same Family and Genus are relatively close in genetic distance. Particularly, P.davidiana ×P.bolleana and Salix purpurea belong to the same family of Salicaceae, PdbSKOR was closely clustered with SpuSKOR in the phylogenetic tree. Eighteen cis-acting regulatory elements, including development regulation, hormone response and stress response, were observed in the promoter region of PdbSKOR gene. qRT-PCR verification showed that PdbSKOR was dominately expressed in roots of 3-year-old hybrid of P.davidiana ×P.bolleana, followed by full bloom flower and inflorescence, and weakly expressed in stems, leaves and fruit flocs. Moreover, the relative expression of PdbSKOR was the highest in roots of tissue-culture plantlets, and was more sensitive to K⁺ depletion, drought and low temperature treatments, whose expression was decreased under K⁺ depletion and drought but induced under low temperature treatment. Expression of PdbSKOR had little response to K⁺ excess treatment. Patch clamp analysis demonstrated that the activity of PdbSKOR channel was activated when the cell membrane voltage reached at +20 mV, and the channel activity was increased correspondingly with the enhancement of positive membrane voltage, typical outward currents were recorded and enhanced alongside with the decrease of external K⁺ concentration. All these findings showed that PdbSKOR was a typical voltage dependent outwardly rectifying K⁺ channel. Conclusion: PdbSKOR gene was cloned and characterized from hybrid of P. davidiana × P. bolleana. PdbSKOR was closely clustered with homolog of SpuSKOR from S.purpurea in the phylogenetic tree. PdbSKOR was mainly expressed in roots of both mature trees and tissue-culture plantlets, and was prone to be regulated by K⁺ depletion, drought, and low temperature treatment. PdbSKOR is a voltage dependent outwardly rectifying K⁺ channel that dominates the K⁺ release in roots of P.davidiana × P.bolleana.

Objective: Nodulin 26-like intrinsic aquaporin proteins(NIPs) are transmembrane proteins essential for controlling the flow of water and other molecules, which play important roles in plant growth and stress tolerance. Temperature and water are important environmental factors for the growth and development of bamboo, the expression patterns of NIP family members of Moso bamboo(Phllostachys edulis) under temperature and drought stresses are of great significance to reveal their functions in response to stresses. Method: A genome-wide analysis of NIP genes and their promoter sequences in Moso bamboo was conducted comprehensively using bioinformatics software. The tissue expression patterns of PeNIPs were analyzed using the transcriptome data, and their expression patterns under temperature and drought stresses were validated by quantitative real-time PCR(qPCR). Two yeast expression vectors of PeNIPs were constructed to analyze their effects on drought and salt stress tolerance of yeast. Result: A total of 14 NIP genes were obtained from the genome of Moso bamboo (PeNIP1-1-PeNIP1-6, PeNIP2-1-PeNIP2-4 and PeNIP3-1-PeNIP3-4), of which the number of introns varied from 3 to 5. A variety of stress and hormone-related regulatory elements were found in the promoters of PeNIPs. The proteins encoded by PeNIPs had completely conserved domains of NIP family. The length of PeNIPs ranged from 235 aa to 297 aa with molecular weight of 24.03-31.84 kDa. The prediction of subcellular localization showed that all PeNIPs were localized on the plasma membrane. Collinearity analysis showed that a total of 27 pairs of fragments were found in 12 PeNIPs and 8 rice NIP genes. All the values of nonsynonymous and synonymous substitution ratios(K_a/K_s) were less than 1, indicating that these PeNIPs had undergone strong purification selection after replication in evolution. In the phylogenetic tree constructed with NIPs of P. edulis and other 5 species, all the NIPs were clustered into three groups(Ⅰ, Ⅱ, Ⅲ), which included 6, 4, and 4 members of PeNIPs, respectively. A total of 10 conserved motifs were found in PeNIPs, of which motif 1, 2 and 4 were common to all PeNIPs. Gene-specific expression analysis based on transcriptome data showed that there were some differences in the expression levels of different PeNIPs in 26 different tissues of Moso bamboo. For examples, PeNIP1-3, PeNIP1-4 and PeNIP1-5 of group I expressed in roots, but hardly expressed in bamboo shoots; four PeNIP2s of group Ⅱ as well as PeNIP3-1 and PeNIP3-2 of group Ⅲ had higher expression levels in roots and shoots. The results of qPCR demonstrated that with the extension of stress duration, 8 genes were up-regulated and 2 genes were down-regulated under 4℃ stresses, and 2 genes were up-regulated and 4 genes were down-regulated under 42℃ stresses. While under the drought stresses there were 3 genes up-regulated. The yeasts expressing PeNIP1-1 and PeNIP2-2 all grew better on the media supplemented with sorbitol or NaCl than the control. Conclusion: Fourteen PeNIPs belonging to NIP family were identified in Moso bamboo. There were some differences in the molecular characteristics and expression patterns of PeNIPs, suggesting that they might play different roles in the growth and development of Moso bamboo and in response to environmental stress. The tolerance ability of yeasts expressing PeNIP1-1 and PeNIP2-2 were improved to a certain degree, indicating that they might have important roles in the stress response of Moso bamboo.

Objective: The comprehensive evaluation of forest quality is the premise and key of forest management decision-making. In order to solve the imbalance development of forest caused by simply emphasizing the accumulation of stand quality, this paper attempted to propose different homogeneity indices based on isoperimetric theorem and equal circle theory, and to construct more universal evaluation function, so as to provide a reference for the problem diagnosis and precise improvement of stand quality. Method: The forest quality comprehensive evaluation of Quercus aliena var. acuteserrata natural forest in Xiaolong Mountains forest region in Gansu Province(a and b), broad-leaved Pinus koraiensis forest in Jiaohe forest region in Jilin Province(c and d) and simulated natural forests(d and f) were taken as examples. 10 indexes were selected from forest structure and vitality, each index was normalized and positive firstly, and the radius and central angle of each sector in unit circle represented the value and weight of each index. The extracted area of the closed graph was used to characterize the accumulation of forest quality(ω_i1). The indices α_i2 and β_i2 were constructed based on the relationships between extracted area and arc length, and the isoperimetric theorem. Similarly, another index γ_i2 was proposed based on the relationships between area and perimeter in the equal circles. The forests(c and e, d and f) with equal accumulation values were used to verify the validity of these three homogeneity indexes of forest quality(ω_i2). Then, a comprehensive evaluation function F_i was constructed based on the geometric mean value of ω_i1 and ω_i2 to compare the quality of four natural forests. Result: When the accumulative values of all evaluation indices were equal, the homogeneity values of α_i2, β_i2 and γ_i2 in the broad-leaved P. koraiensis forest stands c and d were smaller than those simulated stands e and f, showing a consistent evaluation result. The accumulation, homogeneity and comprehensive evaluation sorting results of both Q. aliena var. acuteserrata natural forest and broad-leaved P. koraiensis forest were d > a > c > b. Therefore, the stand d had the best forest quality, followed by stands a and c, and the stand b was the worst. Conclusion: The value and weight of each index could be represented by the radius and central angle of each sector in improved unit circle, respectively. ω_i1 could effectively quantify the accumulation of stand quality. The existed β_i2 and newly proposed α_i2 and γ_i2 could well express the homogeneity among different evaluation indices of forest quality, and their evaluation results have strong consistency among different natural forests. The comprehensive evaluation method of stand quality simultaneously considering accumulation and homogeneity was more comprehensive and objective, and its results would present obvious implications to the potential problems diagnosis of forest quality and the decision-making of forest management, so as to effectively improve the forest quality and promote their balanced development.

Objective: In individual tree segmentation using three-dimensional point could data, common problems include insufficient detection of the understory trees, the low proportion of true positive detections which decreases the effectiveness of the extracted information, and the detection being sensitive to the point density and the complexity of the forest structure. This study aimed to solve these problems by improving the segmentation algorithm, which was expected to support the implementation of the algorithm in the practice. Method: In this study, we proposed an algorithm for the detection and delineation of individual trees in heterogeneous and dense forests based on multi-slice clustering by using low density point cloud data, and the procedures for slicing, detection, segmentation and matching were also improved. Result: The results showed that the improved algorithm could achieve the detection and delineation of individual trees in heterogeneous and dense forests. The obtained trees could be reasonably matched with field trees, where the proportion of accurately extracted trees was 88.70%. Furthermore, the accuracy of individual tree height and mean height were 92.38% and 99.84%, respectively. The highest accuracy of the forest-structure parameters was 89.65%. Conclusion: In general, the main accomplishments of this study were as follows: 1) through the improvement of multi-slice clustering to the algorithm, we enhanced the detection capacity for understory and regeneration trees. 2) Through the establishment of an effectiveness index, named validity index, we were able to assess the effectiveness of the detection and delineation results. 3) Through the addition of the stand spatial structure parameters, we were able to utilize the prominent capacity of LiDAR in obtaining vertical structure information.

Objective: Climate is considered as a potential driver of tree growth. Cyclobalanopsis glauca is an important timber species in southern China. However, we lack an understanding about the growth of this species and its response to climate. The purpose of this study was to explore the long-term effects of climate on the growth of C. glauca in order to provide a basis for the management decision of C. glauca forests under future climatic changes. Method: In this study, based on the data of C. glauca trees dissected in Lutou forest farm, Hunan Province, we constructed the re-parameterization model and the nonlinear mixed-effects(NLME) model with climate variables by using the Mitscherlich growth equation as the basic model, and the diameter at breast height(DBH) growth of C. glauca under the three representative concentration pathways(RCP2.6, RCP4.5 and RCP8.5) in the future was also predicted. Result: 1) The NLME growth model could accurately describe the complex nonlinear relationships between the DBH growth of C. glauca and climate variables, and exhibited more advantages than the traditional regression models in terms of fitting accuracy and error level. 2) The incorporation of climate variables enabled the growth model of C. glauca to respond to the impacts of climate changes on tree growth. The mean coldest month temperature was the most important climatic factor affecting the DBH growth of C. glauca, and was negatively correlated with tree DBH growth. Other climate factors were not included in the growth model because they were not statistically significant. So their effects on the growth of C. glauca were not clear. 3) The response of the DBH growth of C. glauca to different climate scenarios was different. High emission RCP8.5 had a greater negative impact on the DBH growth of C. glauca, while low emission RCP2.6 had a relatively small negative impact. These effects would become more pronounced over time. It was estimated that by 2100, the DBH growth of C. glauca at 30 ages would decrease by 6.3%, 15.6% and 53.1%, respectively, under the scenarios of RCP2.6, RCP4.5 and RCP8.5, compared with the current climate conditions. Conclusion: This study might be a beneficial exploration on the influences of climate changes on the growth of C. glauca, and the NLME DBH growth model for C. glauca proposed in our paper presented the advantages of climate-sensitivity, statistically reliability and predictive effectiveness, etc. These findings of the study would contribute to address the challenges of future climate changes in forest management.

Objective: Traditional forest carbon stock estimation is considered as a heavy workload and high cost in labor and financial resources. In this study, a simple and accurate algorithm was proposed for forest carbon stock estimation. Method: The vertical images of the stand contain two kinds of information(density and height), which is related to the forest carbon storage directly. Firstly, a tree identification algorithm was proposed. Based on the global threshold, the classification of pixels was determined by combining the feature of neighborhood pixels which function is to weaken the influences of uneven light on the gray level of the image. Then, a parameter which is closely related to the forest carbon stock and calculation method was proposed. Finally, the parameter was used as input in a prediction model to estimate carbon stock. Result: The results showed that if there were more than 6 similar pixels in the neighborhood of 3×3 centered at the central pixel, the pixel was also classified as the same category as the similar pixels. The method which used the relationships with adjacent pixels to determine the classification of the current pixel has the characteristics of expansion and corrosion. Therefore, this algorithm can increase the accuracy of forest image classification, which was better than the simple global threshold method. As for the prediction model of carbon stock, the accuracy of the two-parameter linear equation estimation was close to the logistic model of three-parameters and the Logistic model. If the virtual variable which represents the altitude was added into the ordinary model, the prediction accuracy of the carbon reserves can be improved greatly. Taking Larix gmelinii as an example, the hypothesis that carbon stock per unit area can be accurately estimated based on the forest vertical image is verified. Conclusion: This study improved the classification accuracy of the symmetric cross-entropy algorithm by taking into account the category of neighbor pixels. This improved algorithm could achieve higher classification accuracy by showing robust performances to the changes of illumination. In terms of the carbon storage prediction model based on image data, the logistic curve might show a good adaptability. Considering the altitude factor could reduce the estimation error, it is necessary to estimate the carbon storage at different altitudes in practical application.

The larvae of Analcellicampa spp. (Hymenoptera, Tenthredinidae) are fruit borer of Cerasus spp. (Rosaceae). It has been reported in many provinces and regions in China that Cerasus spp. fruits are damaged severely by sawfly borers, but the name of the sawfly was unknown or misidentified. In this paper, a new species of Tenthredinidae collected from Gansu, Analcellicampa wui Niu & Wei, sp. nov., the larvae bore and eat the young fruits of Cherry, is described. The new species, A. wui, is similar to A. danfengensis (Xiao, 1994) from Shaanxi, Henan, Hubei and Hunan Provinces but differs from the latter by the followings: the apex of each coxa and entire trochanter yellowish brown; the hind tibia largely and antennomere 2 pale brown; the epicnemium of mesepisternum pilose and without naked area; the free abscissa of vein Rs basad the apex of vein 1M and remote from it, vein R+M as long as 1m-cu and much shorter than vein 1M; vein 2A of hind wing very short and about as long as cu-a; the abdominal tergite 1 deeply and triangularly incised with inner margins almost straight; lancet with large tangium, middle segments with distinct annuli and narrower than subapical segments. The K2P distance between the COI sequences of A. wui and A. danfengensis, and between those of A. wui and A. xanthosoma, are 7.29% and 8.54% respectively. A key to genera of Hoplocampini and 3 known Chinese species of Analcellicampa are also provided to facilitate the identification of the pests.

Objective: The mixed forest of Korean pine (Pinus koraiensis) with broad-leaved tree species is the climax forest community in Changbaishan Mountains of Northeast China. There are abundant animals and plants species. In this paper, the saproxylic beetles (Coleoptera) species composition, diversity and the effects of different forest stand factor on the beetles were analyzed in the Korean pine and broad-leaved trees mixed forests. This study aimed to reveal the interaction mechanism between habitat change of forest and saproxylic beetles, as well as to provide basis information for evaluating role of nature forest in protecting the diversity and effects of different habitats on diversity of saproxylic beetles. Method: The saproxylic beetles specimens were collected by flying intercepted traps in Korean pine and broad-leaved trees mixed forests, poplar-birch forests, and ash-walnut forests during the whole active period of the beetles from middle May to late August of 2012 and 2013. The saproxylic beetles were identified by beetles biology, related literature and foreign saproxylic beetles database. Result: Totally 239 beetle species in 39 families were collected, among which 203 species, and 7 465 individuals belonged to saproxylic beetles. The number of the species and individuals of Elateridae, Staphylinidae, Nitidulidae, Cerambycidae were relatively richer. Helota gemmata and Rhysodes craciulus were collected for the first time in this area. The diversity of saproxylic beetles in two Korean pine and broad-leaved tree mixed forests was higher, while it was lower in poplar-birch forest and ash-walnut forest. The species number, individual number, richness index, diversity index of saproxylic beetles were significantly different in different stands, and they were higher in two Korean pine mixed with broad-leaved tree forests than in poplar-birch forest and ash-walnut forest. The canopy density, mean DBH, hectare stock, hectare stems, and shrub coverage had different effects on different saproxylic beetles groups. The canopy density, mean DBH, hectare stock had positive effects on most saproxylic beetles groups. Conclusion: The number of species and individuals of saproxylic beetles are abundant in the Korean pine with broad-leaved tree forests. The Korean pine mixed with broad-leaved tree forests greater stand age, DBH and stock has higher diversity of the saproxylic beetles, and it may play an important role in maintaining the diversity of saproxylic beetles. The number of species and individuals of Cerambycidae is higher in the Korean pine mixed with broad-leaved tree forests than that in the poplar-birch forest and ash-walnut forest. Elateridae is the largest group in the Korean pine mixed with broad-leaved tree forests, and it is different from other groups, the number of Elateridae is the more abundant in the poplar-birch forest with hectare stems and shrub coverage.

Objective: Phyllostachys edulis is a main bamboo species in term of both economic and ecological benefits and the sawfly Eutomostethus deqingensis, a defoliator pest, severely attacks the bamboo. It is helpful for effective control the pest by surveying its oviposition habits in different ecological habitats and the effects of host nutritional conditions on its ovipasition selection. Method: The bamboo forests with different structure and environmental conditions were randomly selected as sample sites, then the damage rate of E. deqingensis and the total number of eggs laid in each bamboo were investigated. Meanwhile, the factors, water content, the content of nutrient elements(N, Na, K, C), and the thickness of upper and lower epidermis of bamboo leaves were measured. Finally, the relationships between the factors with oviposition preference of E. deqingensis adults were analyzed by Stepwise Discriminant Analysis. Result: 1) Most eggs were laid on the leaves in the middle and high branches of the bamboo, and the total number of eggs on the leaves of the bamboos grown in the slope bottom (3 835.0 ±385.2 per bamboo) was significantly higher than that in the slope upper part (864.5 ±215.5 per bamboo, P < 0.01). 2) Bamboo age had a significant impact on oviposition preference of E. deqingensis, and the number of eggs on leaves of one-year-old bamboo(3 954.6 ±1 247.4) was significantly higher than that of two-year-old bamboo(144.3 ±49.3, P < 0.001). The oviposition preference showed significant positive correlation with the water content of bamboo leaves(54.90% for newly grown leaves and 51.99% for two-year-old leaves, P < 0.05), no significant correlation with the thickness of leaf epidermis(P>0.05).3) There were significant differences in N and Na content(P < 0.01)between newly grown leaves and two-year-old leaves, while no significant differences in C and K content were found. The result analyzed by Stepwise Discriminant Analysis showed that N content was the dominant factor affecting oviposition preference of E. deqingensis, followed by Na. Conclusion: E. deqingensis adults prefer to laying eggs in the newly grown leaves of the bamboos growing at the bottom of slope, especially the middle part of the bamboos. The age, water content, and the content of N and Na of leaves are significantly related to the oviposition preference of this insect. The pesticide-injecting in the newly grown bamboo cavity is an effective method to control E. deqingensis.

Objective: This study aimed at providing spatial guidance for prevention and control of risk management, and the factors and risks affecting the occurrence and spread of pests were described as continuous variables on the spatial grid points to improve the precision of measurement and warning. The raster model of GIS (geographic information system) was used to express the variables in digital matrix and spatial unit, and the multivariate logistic probability model with 0-1 measure was established by SPSS to present the risk of pest occurrence. The flowchart was illustrated by taking Hyphantria cunea as an example. Method: Based on the national quarantine data in township of Hyphantria cunea during 2011 and 2016, simulation of host, meteorological factors, biogeographic environment, and main factors impact variables was carried out to analyze the risk pattern of occurrence and spread of Hyphantria cunea. Taking 250 m as the minimum spatial grid, the risk probability of any spatial geographic unit is described. Result: Besides bioclimates, the impact of human mobility and logistics variables is significant in risk assessment. The high risk is located in the eastern farmland and construction land of man-made vegetation regions, mainly in Liaoning, Beijing, Tianjin, Shanghai, Hebei, Shandong, Henan, Anhui, Hubei, Jiangsu, Shanxi and other provinces and cities, and has the trend of spreading to Jilin, Inner Mongolia, Hunan, Jiangxi, Xinjiang, Ningxia and other provinces. Conclusion: The matrix model and 0-1 probabilistic measure are used to describe the risk of occurrence and diffusion of pests. The simulation of human impacts spread can effectively improve the accuracy of measurement and warning. The human activity intensive region is not only the epidemic area, but also the transmission path. The natural vegetation of the mountain forest system has a blocking effect on the propagation and diffusion. It is of great significance for the prevention and control to strengthen the restoration and construction of near-natural forests in high-risk areas and to increase the quarantine of important passageways.

Objective: The aim of this study was to investigate the application of time-temperature superposition principle(TTSP) to orthotropic creep of Chinese fir(Cunninghamia lanceolata). Method: Dynamic mechanical analysis(DMA 2980) was used to determine a sequence of short-term(20 min) tensile creep for longitudinal(L), radial(R) and tangential(T) specimens with a moisture content of 0.6% in the temperature range of 30℃ to 150℃ and at three stress levels. All creep curves at other temperatures were shifted along the log time axis to superimpose them on a reference temperature(i.e. 30℃ in this study) curve. The extended isothermal creep strain master curve was over a wide range of time. The smooth master curve should ensure that not only the values of creep strain match, but also the slope. The horizontal shift factor was determined to be a function of temperature and fitted into the WLF equation and Arrhenius equation with the least squares method. Result: Creep strain increased with increasing stress and temperature for each specimen, irrespective of grain orientation. There were differences in creep strain among the specimens with three grain orientations. Creep strain for L specimen was significantly lower than that for R and T specimens, and T specimen was higher than R specimen almost twice. TTSP was well matched for R and T specimens only using horizontal shift factor to construct master curves, and the extended time scale of master curves was from 10³ s to 10⁷ s. An additional vertical shift factor was applied to construct smooth master curve of L specimen, the extended time scale of master curve was about reduced from 10⁵ s to 104.5 s. In addition, only the excellent fit of the horizontal shift factor to the WLF equation(standard error of estimate < 13.61%) was observed over the entire temperature range in all orthotropic directions. Conclusion: The validity of TTSP to characterize the creep behavior of dry wood was found in the range of 30℃ to 150℃. The TTSP were constructed for R and T specimens using horizontal shift factor, while horizontal shift factor and vertical shift factor were used for L specimen. The WLF equation provided a better fitting with horizontal shift factor in all orthotropic directions.

Objective: Using near-infrared spectrum(NIR) analysis technology, a wood elastic modulus prediction model based on support vector machine optimized by artificial bee colony algorithm(ABC-SVM) was proposed, which was expected to provide a scientific reference for non-destructive prediction of wood elastic modulus. Method: Taking 294 samples of Cunninghamia lanceolata as experimental materials, the elastic modulus of the samples was measured by conventional mechanical method, and the near-infrared diffuse reflection spectra of the samples were collected. The 350-2 500 nm spectrum was selected and the original spectrum was preprocessed by first-order derivation and 15-step exponential smoothing. Using principal component analysis to reduce the data, then the partial least squares regression(PLS) model, support vector machine regression(SVR) model and the ABC-SVM model were established to predict the elastic modulus of Cunninghamia lanceolata. The determination coefficient(R²), the root mean square error(RMSE), the mean absolute percentage error(MAPE) and the mean absolute error(MAE) were used to evaluate the advantages and disadvantages of the three models. Result: The R² of PLS model is 0.726 700, the RMSE is 6.744 9, the MAPE is 0.063 5, and the MAE is 5.065 6. As for SVR model, the R² is 0.935 305, the RMSE is 3.528 1, the MAPE is 0.023 7, the MAE is 1.840 9. Using artificial bee colony algorithm to optimize SVM parameters, the optimal parameters are c=5.670 51, g=0.031 25. The R² of ABC-SVM model is 0.935 371, the RMSE is 3.526 0, the MAPE is 0.023 7 and the MAE is 1.840 0. All three models could effectively predict the elastic modulus of Cunninghamia lanceolata. Conclusion: 1) Observing the index of determination coefficient(R²), both SVR and ABC-SVM models have better prediction performances than PLS model, and ABC-SVM has the best prediction performance. 2)According to the obtained error results(RMSE, MAPE and MAE), the MAPE of the three models is within the acceptable range, and the ABC-SVM model has the smallest indicators for the error, indicating that the model is efficient and scientific in predicting elastic modulus of Cunninghamia lanceolata.

Objective: This study was carried out with the aim to provide scientific bases for the wood processing and utilization of Catalpa bungeana wood through the characterization of the heterogeneity of chemical compositions in various heights and radial regions. Method: The contents of benzyl alcohol extracts, polysaccharides and lignin of the heartwood and sapwood at various heights of C. bungeana wood were analyzed. The structural features of the lignin in the corresponding regions were also characterized through whole cell wall dissolving system combined with two-dimensional heteronuclear single-quantum coherence NMR technique. Result: The contents of the benzyl alcohol extracts in sapwood of C. bungeana wood were higher than those in the heartwood. More extracts were found in the heartwood near the sapwood compared with those in the heartwood near the tree heart. There were some differences in the chemical compositions of the extracts between the sapwood and heartwood of C. bungeana. However, no relationship could be found between the extract contents and tree heights, and the differences in extract content between sapwood and heartwood at different heights were identical. The lignin content in sapwood of C. bungeana was lower than that in heartwood. However, no relationship could be found between the lignin contents and heights. The lignin of C. bungeana wood was made up of guaiacyl(G) and syringyl(S) phenylpropane units. The molecular structure of the lignin at various heights of the C. bungeana wood was similar with each other. However, more β-5' linkages could be found in the lignin of the heartwood as compared with the lignin of the sapwood. Xylan was the predominant polysaccharide in hemicelluloses of the C. bungeana wood. The content of the polysaccharides in sapwood was higher than that in heartwood. However, no obvious differences in the content of the polysaccharides in the wood obtained from various heights. Conclusion: There were obvious differences in content and molecular structure of the chemical compositions between sapwood and heartwood of the C. bungeana. The accumulation of lignin and biosynthesis of chromogenic substances both occurred during the formation of heartwood of C. bungeana. Some differences in content of the chemical compositions could also be found in the wood at various heights of the C. bungeana. However, the differences had nothing to do with the tree heights. The molecular structures of the chemical compositions in a specific region at various treat heights were almost the same. The differences of chemical composition content and properties in radial direction should be taken into account during the processing of the C. bungeana wood.

Walnut is the most widely cultivated nut tree species, as well as an important woody oil crop in the world. In recent years, the cultivation scale of walnut in China has expanded rapidly, but the yield per unit area is relatively low. Inadequate nutrient management measures are one of the major reasons. In this paper, we review the literature relevant to walnut production at home and abroad, summarize the research results of walnut mineral nutrition, and clarify the suitable soil environment and mineral nutrition characteristics of walnut growth, and the nutritional functions and abundance and deficiency effects of essential mineral elements in walnut, so as to provide reference for improving quality and efficiency of walnut industry through high-efficiency nutrient management and fertilization practice. Walnut has a strong adaptability to the soil environment, and even the ameliorated soil with strong acid, strong alkali and high salt can also produce high yield. Walnut production has a relatively high demand for mineral nutrients, and the contents of marcoelements in adult trees are in the order of Ca, N, K, Mg, P and S. The abundance and deficiency standards of major mineral elements in adult walnut trees were sorted out according to the content of the elements in midsummer leaves, and the physiological disease symptoms caused by nutrient stress and their occurrence period were described. N, P and K deficiency can significantly affect the growth of young trees. The increase of some non-physiological diseases may be related to the abnormal nutrition of P and Ca. Walnut is sensitive to B and Cl, and their excessive supply is easy to cause toxicity. It has been proved that N, K, Ca, B, Zn and Cu are closely related to the quality and yield of walnut, however the roles of P, Mg, Fe and Mn need to be further clarified. Based on the analysis of the research difficulties in walnut mineral nutrition and the summary of the working experience in developed countries, some research and practice suggestions on walnut mineral nutrition in China are put forward.

Objective: Wuyishan National Natural Reserve in Jiangxi has a large local distribution area of Tsuga chinensis var. tchekiangensis population. Niche characteristics of dominant plants therein coniferous(T. chinensis var. tchekiangensis) and mixed broad-leaf forest were investigated, which was not only beneficial to reveal the utilization potential of the dominant plants to their surrounding resources and the competition between different plants for similar resources, but also provided a scientific basis for protection of ancient T. chinensis var. tchekiangensis and maintenance of the stability of virgin forest ecosystem. Method: Based on investigation data of woody plants in permanent plot at 1 800 m altitude in Jiangxi Wuyishan National Natural Reserve, to inquire into the position of T. chinensis var. tchekiangensis in the mixed forest, niche breadth of main plants and niche overlap between plants in arbor layer, regeneration layer, shrub layer and herb layer were calculated by corresponding calculation methods to compare. Result: The species with the largest niche breadth in arbor layer were T. chinensis var. tchekiangensis and Cyclobalanopsis glauca, while C. glauca was the species with the highest niche overlap to T. chinensis var. tchekiangensis, indicating the most intensive competitive relationship between them. The resources utilization potential of Symplocos phyllocalyx and Stewartia gemmata were weak in arbor layer with the least niche breadth. In regeneration layer, Illicium minwanense and C. multinervis with wide distribution had strong resource utilization potential, and niche breadth of them were the largest. While the niche breadth of T. chinensis var. tchekiangensis was small, itrepresented a poor degree of dominance in the regeneration layer. Rhododendron fortunei and Rhus punjabensis var. sinica had the highest niche overlap between T. chinensis var. tchekiangensis, resulting in the disadvantage of T. chinensis var. tchekiangensis saplings in regeneration layer. The niche breadth of 7 saplings, such as Styrax hemsleyanus, C. multinervis, R. punjabensis var. sinica, S. phyllocalyx, R. fortunei, C. glauca, and T. chinensis var. tchekiangensis were apparently lower than that of trees in the arbor layer. The species with the largest niche breadth in the shrub layer and the herb layer were Fargesia spathacea and Oplismenus undulatifolius. As a result of a massive quantity and a wide distribution in plot, F. spathacea had a negative effect on the survival of regeneration layer species. Conclusion: T. chinensis var. tchekiangensis was the constructive species in virgin mixed forest, only C. glauca had certain competitiveness with that in the arbor layer. The regeneration of T. chinensis var. tchekiangensis saplings was poor, C. glauca with high dominance may replace T. chinensis var. tchekiangensis. To maintain virgin forest stability and improve the management and protection measures of T. chinensis var. tchekiangensis, the regeneration conditions of T. chinensis var. tchekiangensiscanbe optimized by using artificial disturbance measures such as selective cutting.

Objective: Non-structural carbohydrates (NSC) reserves support tree metabolism and growth when current photosynthates are insufficient, offering resilience in times of stress. Thus, investigation of seasonal dynamic patterns of NSC and the components and the allocation relationship among different organs of trees will help us to better understand the mechanism of carbon allocation in the process of tree growth. Method: In this study, the contents of NSC and its components in coarse roots and stems of the dominant species, Quercus variabilis, in the eastern part of Qinling Mountains, China in growing season and non-growing season were determined. The experiment was conducted from May 2016 to June 2017.We collected samples at semimonthly/monthly intervals during the leaf unfolding period from March to May, atmonthly/bimonthly during the leaf full growing season from June to November, and by one time during non-growing season in February. A total of approximately 130 samples were used to determine their NSC concentrations by Anthrone-sulfuric acid method and the correlations between coarse roots and stems in NSC concentrations were analyzed. Concurrently, the leaf phenology was monitored by direct observation. Result: 1) The contents of NSC and its components in coarse roots and stems of Q. variabilis were significantly different with time(P < 0.05), and the mean content of NSC in coarse roots(13.96%)was much higher than that in stems(6.24%), which was mainly related to the functional differences between the two organs. 2)There were positive correlations in NSC, soluble sugar contents and the ratio of soluble sugar to starch between coarse roots and stems(P < 0.05), but no significant correlation in starch concentration between them. 3)The peak value of NSC concentration in stems occurred in March, whereas that in coarse roots did in February, lagging behind about half a month. This difference between two organs could be explained by the carbon coordination between coarse roots and stems.The increase of stem NSC was synchronized with the decrease of thick root NSC, which followed by carbon demand for annual stem growth initiation. As a ring-porous tree, Q. variabilis leaf bud burst generally occurs after stem growth. Thus, before leaf unfolding, coarse roots provide NSC for the stem growth. Conclusion: The NSC concentrations in the coarse roots and stems of Q. variabilis has an obvious seasonal dynamic change. The species shows coordinated response of carbon storage and growth between coarse roots and stems.