Objective: This study is aimed to through characterization of the changes of contents of active soil organic carbon and nitrogen, and their influential factors in three secondary natural forests with similar microclimate and soil parent materials, to deepen the understanding of the changes of soil organic carbon and nitrogen stock and contents of active components during the course of regeneration of the natural secondary forest. Method: The study site is located in Jiabigou forest zone of Miyaluo town in western Sichuan, where secondary forest was formed through natural regeneration after logging in the 1960s. Soil samples in the top soil layer (0-20 cm) from Acer spp.+Betula spp. deciduous broadleaf forest (ABB), a Betula spp.+Acer spp.+Abies faxoniana mixed broadleaf-conifer forest (BAA) and a Abies faxoniana pure forest (AFF) were collected in late July, 2018. We investigated the changes of contents of soil organic carbon (SOC), total nitrogen (TN), light fraction organic carbon (LFOC), dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved total nitrogen (DTN), dissolved inorganic nitrogen (WDON) microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN), and their relations with physical and chemical soil properties, and species diversity using the method of comparisons of adjacent plots. Correlation analysis was used to reveal the differences of soil active organic carbon and nitrogen fractions. Redundancy analysis (RDA) was determined to decipher the main factors influencing soil organic carbon and nitrogen fractions. Result: The results showed that, due to similar tree species in the ABB and BAA, the contents of SOC, LFOC, DON, and DTN ranked in the order of ABB > BAA > AFF. The contents of SOC, LFOC, MBC, DON, and DTN of AFF compared with ABB and BAA was 46.24% and 41.29%, 51.29% and 31.72%, 46.46% and 41.58%, 54.48% and 28.54%, 56.15% and 48.64% lower, respectively. The content of DOC was in the order of ABB > AFF > BAA. DOC content of AFF compared with ABB and BAA was 25.39% lower and 4.08% higher, respectively. The contents of TN, WDON, and MBN were in the order of BAA>ABB>AFF. The contents of TN and WDON of AFF compared with ABB and BAA was 48.46% and 48.59%, 63.57% and 79.94% lower, respectively. MBN content of AFF was 5.72% lower compared with ABB and 5.26% higher compared with BAA, respectively. Redundancy analysis(RDA) indicated that TN, soil total phosphorus(TP) and Shannon-Wiener index of arbor and herb layers were the major impacting factors for driving changes of soil active organic fraction contents. TN and NO₃^--N played an important role in driving changes of soil active nitrogen fractions contents. Conclusion: The results indicated that the differences of exogenous nitrogen and phosphorus (especially nitrogen) devotion were responsible for the significant differences of soil active carbon and nitrogen fractions, and the growth rhythm of tree and herbaceous plants, the availability of soil nutrient. The contents of topsoil organic carbon and nitrogen fractions in ABB and BAA were obviously higher than those in AFF. The results implied that AFF were not beneficial to the soil nutrient accumulation in the early stages (≤60 a) of natural regeneration after logging. It was therefore better to increase appropriately the proportion of broad-leaf and herbaceous species in managing A. faxoniana forests for improving soil fertility quality.

Objective: The InVEST model and scenario analysis were used to study the spatial-temporal dynamics of water yield in Danjiangkou reservoir area, in order to provide a scientific basis for the improvement and control of water conservation capacity in the reservoir area. Method: The InVEST model was used to quantitatively study the changes of temporal of water yield in 2003, 2013, and 2018. The changes of water yield depth under different land use/cover types were analyzed and compared. The effects of annual precipitation and land use/cover type changes on water yield were investigated by scenario simulation method. Result: The annual water yield of Danjiangkou from 2003 to 2018 showed a trend of a weakening followed by a strengthening, including the annual water yield depth of 310.09 mm and water yield of 1.36 billion m³ in 2003, the annual water yield depth of 146.67 mm and water yield of 525 million m³ in 2013, and the annual water yield depth of 166.06 mm and water yield of 728 million m³ in 2018, which decreased by 46.47% in 15 years. On the whole, the water yield per unit area is not evenly distributed in space. The northern hilly and mountainous areas are 39.84%-57.79% higher than the southern ones. The water yield depth of each land use/cover type showed a trend of a decrease followed by a slow increase. The highest water yield depth was urbanized land (530.35 mm), followed by cropland (292.85 mm), orangery (284.07 mm) and woodland (273.76 mm). Scenario simulation shows that annual precipitation and land use/cover type are the main factors affecting water yield. The contribution rate of precipitation in 2013 was 92.43%, and the change of land use/cover type contributes 64.71% to 2018. Conclusion: The InVEST model can be used to monitor the spatial-temporal dynamic changes of water yield in the reservoir area, and pay close attention to the influence of precipitation and land use/cover type changes on water yield, therefore providing a scientific basis for the improvement of water conservation capacity in the reservoir area.

Objective: The study aims to determine how growth rate of middle-aged Chinese fir responds to understory management. Method: This study was conducted in the framework of an understory management experiment ofsubtropical middle-aged Chinese fir established in 2013. The plantation on the platform was established in 1998. Weset a paired-treatment experiment, with understory left intact in one treatment (CK) and understory removed for the other treatment(UR). By 2016, trees with DBH classes of 12-14 cm and 16-18 cm accounted for 42.6% in CK treatment and 77.1% in UR treatment. During 2016-2018, we studied the stoichiometry, resource acquisition and utilization efficiency, carbon allocation patterns (e.g., structural vs non-structural carbohydrates (NSC) allocations and NSC allocations among different organs) and relative growth rate (RGR) of trees withthese two DBHclasses. Result: The effects of understory removal on the RGR of middle-aged Chinese fir depended on DBH. The understory removal had no significant effect on the RGR of the Chinese fir with 12-14 cm DBH, however decreased the RGR of the Chinese fir with 16-18 cm DBH. For the Chinese fir of 12-14 cm and 16-18 cm DBH classes, the understory removal had no significant effect on the maximum photosynthetic rate, instantaneous water-use efficiency, instantaneous nitrogen-use efficiency, leaf total nitrogen (N) content, leaf total phosphorus (P) content, leaf N/P, leaf NSC(NSC_leaf), branch NSC(NSC_branch), and trunk NSC(NSC_trunk). For the Chinese fir with16-18 cm DBH, understory removal significantly reduced the NSC of new leaves (especially soluble sugar, SS), increased NSC_trunk/RGR and NSC_leaf/RGR (indicatinga priority of carbon storage over growth), and thus decreased the RGR. For the Chinese fir with 12-14 cm DBH, although the understory removal significantly increased the ratio of new leaf SS and old leaf SS, the NSC_leaf/RGR was the main factor in regulating the RGR and the understory removal did not significantly affect NSC_leaf/RGR of Chinese fir with this DBH class. Conclusion: The DBH-dependent effects of understory removal on the growth rate of middle-aged Chinese fir are mainly controlled by carbon allocation rather than by nutrient stoichiometry, resource acquisition efficiency, and utilization efficiency. Objective: The study aims to determine how growth rate of middle-aged Chinese fir responds to understory management. Method: This study was conducted in the framework of an understory management experiment ofsubtropical middle-aged Chinese fir established in 2013. The plantation on the platform was established in 1998. Weset a paired-treatment experiment, with understory left intact in one treatment (CK) and understory removed for the other treatment(UR). By 2016, trees with DBH classes of 12-14 cm and 16-18 cm accounted for 42.6% in CK treatment and 77.1% in UR treatment. During 2016-2018, we studied the stoichiometry, resource acquisition and utilization efficiency, carbon allocation patterns (e.g., structural vs non-structural carbohydrates (NSC) allocations and NSC allocations among different organs) and relative growth rate (RGR) of trees withthese two DBHclasses. Result: The effects of understory removal on the RGR of middle-aged Chinese fir depended on DBH. The understory removal had no significant effect on the RGR of the Chinese fir with 12-14 cm DBH, however decreased the RGR of the Chinese fir with 16-18 cm DBH. For the Chinese fir of 12-14 cm and 16-18 cm DBH classes, the understory removal had no significant effect on the maximum photosynthetic rate, instantaneous water-use efficiency, instantaneous nitrogen-use efficiency, leaf total nitrogen (N) content, leaf total phosphorus (P) content, leaf N/P, leaf NSC(NSC_leaf), branch NSC(NSC_branch), and trunk NSC(NSC_trunk). For the Chinese fir with16-18 cm DBH, understory removal significantly reduced the NSC of new leaves (especially soluble sugar, SS), increased NSC_trunk/RGR and NSC_leaf/RGR (indicatinga priority of carbon storage over growth), and thus decreased the RGR. For the Chinese fir with 12-14 cm DBH, although the understory removal significantly increased the ratio of new leaf SS and old leaf SS, the NSC_leaf/RGR was the main factor in regulating the RGR and the understory removal did not significantly affect NSC_leaf/RGR of Chinese fir with this DBH class. Conclusion: The DBH-dependent effects of understory removal on the growth rate of middle-aged Chinese fir are mainly controlled by carbon allocation rather than by nutrient stoichiometry, resource acquisition efficiency, and utilization efficiency.

Objective: In this study, the inter-annual variation pattern of transpiration water consumption of Pinus sylvestris var. mongolica stand and its relationship with precipitation and groundwater level were determined by continuous and long-term field monitoring, which would clarify the water relationship of the tree species in sandy land, so as to provide reference for improving scientific management level of P. sylvestris var. mongolica. Methods: The sap flow velocity (J_s) of P. sylvestris var. mongolica plantation in the Zhanggutai area of the southern margin of Horqin sandy land was monitored continuously by thermal dissipation probe (TDP) methods for nine years from 2010 to 2018. Stand factors and environmental factors such as meteorology, groundwater level and soil volumetrical water content were simultaneously monitored. Results: The multi-year transpiration intensity of the medium-density P. sylvestris var. mongolicas stand (404 trees·hm^-2) during the growing season (April to October) averaged 163.7 mm·a^-1 with the maximum of 209.5 mm·a^-1. In general, the transpiration intensity rose from April to July, and then declined from July to October. The daily average transpiration intensity in April, July and October was 0.54, 0.98 and 0.36 mm·d^-1, respectively. The maximum intensity of daily transpiration over the whole study period was 1.99 mm·d^-1. The annual transpiration to annual precipitation ratio of P. sylvestris var. mongolica stand was 31.5% on average over the years, ranging from 16.6% to 54.7%. On a monthly scale, the normalized data of the transpiration intensity (T_s) of P. sylvestris var. mongolica showed a linear relationship to monthly precipitation (P_r), monthly average groundwater level (G), monthly average solar radiation (PY), and monthly average soil volumetric water content of 0-60 cm layer with a regression formula: T_s = 0.043 48 + 0.222 99×P_r -0.424 64×G + 1.201 93×PY + 0.307 18×θ_{0-60 cm} (R² = 0.58). Solar radiation had the greatest influence on transpiration intensity. Conclusion: The annual transpiration of P. sylvestris var. mongolica stand with medium density accounts for about one third of the annual precipitation, at most no more than 55.0%. The inter-annual variation of transpiration (the ratio of transpiration intensity to solar radiation) of P. sylvestris var. mongolica is basically consistent with the inter-annual changing trend of hydrology from dry to wet or from wet to dry dominated by precipitation, as well as with the inter-annual changes of groundwater, but not exactly the same.

Objective: The objective of this study is to investigate and analyze the dynamic change patterns of photosynthetic characteristics, the contents and endogenous hormones in the process of fruit development of Idesia polycarpa, so as to provide reference for further study the mechanism of fruit development and regulation technology. Methods: In this paper, I. polycarpa derived from Chengdu was taken as the research material. The activities of superoxide dismutase (SOD) activity, peroxidase (POD) activity, catalase (CAT) activity, the content of MDA, soluble protein and soluble sugar were measured at different stages of fruit development. The contents of indole-3-acetic acid (IAA), abscisic acid (ABA), gibberellin acid (GA₃) and zeatin nucleoside (ZR) were determined by HPLC. The indexes of net photosynthetic rate (P_n), Transpiration rate (Tr), stomatal conductance (G_s) and intercellular CO₂ concentration (C_i) of plants were measured by LCpro-SD portable photosynthetic apparatus. Results: 1) SOD and POD activities showed overall a "down-rising" trend during the fruit development of I. polycarpa; CAT activity showed a "up-down" trend. MDA content showed an upward trend. The content of soluble sugar and soluble protein showed a "up-down" trend. 2) ABA content increased rapidly in period of fruit color change and ripening, and GA₃ content increased as a whole. The content of IAA was higher in fruit growth stage. The content of ZR was higher in both rapid growth and ripening stage of fruit. There were significantly positively correlations between ABA, GA₃ and ZR with soluble protein. 3) At different stages of fruit development, the diurnal change of P_n showed an asymmetric bimodal change trend, with an obvious phenomenon of "photosynthetic siesta", In addition, P_n was the highest at the slow growth stage. The trend of light response curve at different stages of fruit development was similar. The maximum net photosynthetic rate (P_nmax) was the highest, and dark respiration (R_d) and light saturation point (LCP) were the lowest at the slow fruit growth stage. LCP was positively correlated with ABA, GA₃ and ZR. The CO₂ response curve showed that there were higher P_nmax and CSP, and lower CO₂ compensation point (CCP) and photorespiration rate (R_p) at the slow growth stage. Conclusion: The dynamic changes of antioxidant enzyme, ABA, IAA, GA₃ and ZR contents in the fruit of I.polycarpa at different development stages are consistent with the fruit development rules, which would play an active regulatory role in the fruit development process. At the slow growth stage of I. polycarpa, there is a wide range of light energy and CO₂ utilization range as well as the relatively high net photosynthetic rate. However, at this time, high temperature and drought, stomatal conductance increases and transpiration rate reaches the highest. Therefore, timely irrigation should be carried out to maintain a high photosynthetic rate and provide ample photosynthetic products for I. polycarpa to ensure the excellent quality of the fruit.

Objective: The aim of this study was to analyze the genetic diversity of Chinese fir(Cunninghamia lanceolata) breeding populations, and to detect its genetic structure and gene flow, further to provide a scientific basis for long term breeding and sustainable management of Chinese fir. Method: Using nuclear and chloroplast microsatellite markers, a total of 520 clones of 2 breeding populations respectively of two national seed bases(Youxian and Lechang)were analyzed to compare their genetic diversity among different generations. Result: nSSR data showed that total genetic diversity of breeding populations was 0.687. Youxian and Lechang seed bases displayed a high genetic diversity, with expected heterozygosity of 0.678 and 0.667, respectively. With the advancement of breeding process, genetic diversity of advanced-generations of the two seed bases tended to decrease gradually. The average number of alleles in the two bases (Youxian and Lechang) decreased from 9.612 (F₁) to 8.750 (F₂), the F₃ generation of the Lechang Base had the smallest allele number 6.833, the expected heterozygosity was decreased by less than 6.46% among generations. cpSSR markers also showed a clear change of genetic diversity, but the changing trend was different in the two seed bases among different generations. With the advancement of breeding process, genetic diversity of the Youxian Base gradually increased, while Lechang Base showed a trend of a decline followed by a rise. This difference is related to the evolution model of chloroplast and nuclear genomes, and also affected by the number and sources of breeding materials in the two seed bases. Conclusion: Chinese fir breeding populations in the two national seed bases have high level of genetic diversity. With the advancement of breeding process, genetic diversity of advanced-generation breeding populations was decreasing gradually, but the reduction rate was less than 6.46%, suggesting that the advanced-generation breeding strategies and methods of Chinese fir were scientifically sound and effective.

Objective: The aim of this study was to clone and identify NAC (NAM, ATAF1/2 and CUC) transcription factors related to secondary cell wall formation in Populus trichocarpa. Based on the analysis of tissue-specific expression pattern, the phenotype and downstream regulatory network of transgenic plants, our results provide some new insights into the mechanism of the gene regulatory network of secondary cell wall biosynthesis in poplar, laying a foundation for the use of this gene in forest germplasm innovation. Method: Based on the previous transcriptome data, PtrNAC128, which was preferentially expressed in the stems of P. trichocarpa, was cloned. Relative expression of PtrNAC128 in roots, stems and leaves were analyzed by qRT-PCR analysis. The subcellular localization of PtrNAC128 was analyzed by gene gun bombardment method; 35S∷PtrNAC128-GFP plant binary expression vector was constructed and transformed to Populus tomentosa. Anatomical cross-sections of transgenic and wild-type plants were observed by paraffin analysis method, and the effects of PtrNAC128 overexpressing on the components of poplar secondary cell wall were examined. The expression fluctuation of key enzyme genes and NAC, MYB transcription factors which regulating the biosynthesis of lignin, cellulose and hemicellulose synthesis were detected by qRT-PCR analysis. Result: PtrNAC128 clustered in one branch with Arabidopsis ANAC075, with typical domains and intact C terminal activation regions. PtrNAC128 was expressed in all tissues tested, with the highest expression level in old stems and the lowest expression level in leaves. The expression of PtrNAC128 in old and young stems was 23.49 folds and 11.44 folds higher than that in young leaves, respectively. Subcellular localization analysis indicated that PtrNAC128 was localized into the nucleus. The secondary xylem width of PtrNAC128-overexpression (PtrNAC128-OE) transgenic plants had significantly increased to 1.42-1.51 folds, while the number of secondary xylem cells increased to 1.22-1.31 folds compared to the wild-type plants. The Klason lignin contents in the stems of PtrNAC128-OE lines were significantly increased by 12%-22% compared to the wild-type plants. Moreover, no significant effect was detected on the hemicellulose biosynthesis, while cellulose content increased by 7.4%-13.1% in the PtrNAC128-OE lines. The qRT-PCR analysis revealed that the relative expression levels of key synthetic enzyme genes of lignin and cellulose as well as some secondary wall-associated NAC and MYB transcription factors were elevated in the PtrNAC128-OE lines. Conclusion: These results suggested that PtrNAC128 may positively regulate the secondary cell wall biosynthesis by activating the enzyme genes and transcription factors of lignin and cellulose biosynthesis in poplar.

Objective: This study aimed to propose a theoretical basis for the uncertainty analysis in modeling young tree growth. A height increment model for young Pinus tabulaeformis was built using research inventory data of pine-oak forests in the Qinling Mountains. The effect of uncertainty sources on model predictions was then analyzed by disaggregating the predictive uncertainty into contributions from every single parameter. Method: The height increment model of young P. tabulaeformis was constructed using 132 sampled young trees. The Markov Chain Monte Carlo (MCMC) method was used to obtain the joint posterior distribution of parameters,and to quantify the uncertainty of model outputs,in terms of the uncertainty of prediction error,measurement errors of the inputs and the parametric uncertainty. A combination of Bayesian statistics and global sensitivity analysis (GSA) was used to quantify the uncertainty propagation. The contributions of different parameters to the predictive uncertainty were represented by the variable coefficient (CV,%) and 95% Bayesian credible intervals (B). Result: 1) The largest uncertainty source of model predictions was the random error,accounting for 51% of the total uncertainty. The least uncertainty source was parametric uncertainty,accounting for 43% of total uncertainty. The minimum uncertainty source was the measurement errors of model input,i.e. light interception (LI) and crown competition factor (CCF),accounting for only 6% of total uncertainty. The 95% credible interval of model prediction included 97% of observations,and sufficiently covered the ranges of random errors of observed data. 2) The parameter relating to CCF resulted in the largest contribution to the uncertainty of the predictions,and the propagated uncertainty attributed 64.87% of total parametric uncertainty. Parameters of LI and slope (SL) propagated 15.88% and 10.02% of total parametric uncertainty,respectively. The parameter of height accounted for only 1.78%,and the uncertainty contributed from other parameters was less than 1%. The uncertainty propagated from parametric interaction was less than 1%,except for the parameters relating to CCF and SL. 3) The Bayesian MAP (maximum a posteriori probability estimate) showed that the effects of CCF,LI and SL on the 5-year height increment of young P. tabulaeformis were negative,but positive on tree height. The results revealed that the higher parametric uncertainty,the less effects of corresponding variables on predictions. Conclusion: The uncertainty sources in the predictions of height increment for young P. tabulaeformis were complicated. Bayesian statistics and global sensitivity analysis (GSA) were combined to quantify and explain the uncertainty of young P. tabulaeformis growth by disaggregating the uncertainty into multiple sources. The contribution of each parameter to predictive uncertainty was quantified by sampling from the joint posterior distribution of parameters. Such a Bayesian approach might be capable for the quantification and disaggregation of uncertainty analysis in simulating of forest ecosystem dynamics.

Objective: Stem taper functions are important components in forest management and planning systems. Currently,there is no taper function for Betula platyphylla in northeast China,therefore,it is necessary to develop the taper function for this species. Eight commonly used taper functions in forestry were compared to evaluate which would provide a better prediction for diameter at a specific height and total volume for B. platyphylla in northeast China. Method: The data used in this study were collected from 253 destructively felled sample trees with 3 795 diameter/height measurements in the northwest of the northern slope of Yilehuli Mountains of northeast China. A first-order continuous autoregressive error structure was used to model the error term and account for autocorrelation. Multicollinearity was also evaluated with condition number. Coefficient of determination (R²),mean absolute bias (MAB),root mean square error (RMSE) and mean percentage of bias (MPB) were selected as evaluation criteria of models. Comparison of the taper models was carried out using goodness-of-fit statistics,box plots of diameter and volume residual distributions and validation statistics. Result: 1) In terms of model fitting statistics, the models of Kozak (2004)-2, Fang et al. (2000) and Max et al. (1976) were the top three models. The model of Sharma et al. (2001) showed the poorest performance. 2) Based on the box plots of diameter and volume residuals, the models of Bi (2000), Max et al. (1976), Kozak (2004)-2 and Fang et al. (2000) were more accurate in diameter and volume prediction with smaller errors and almost similar residual diameter and volume distribution. The models of Sharma et al. (2001), Sharma et al. (2004), Sharma et al. (2009) and Kozak (2004)-1 had non homogeneous distribution of the diameter residuals along different sections of the stem. 3) Model validation also confirmed that Max et al. (1976), Kozak (2004)-2 and Fang et al. (2000) showed better performances. In general, the model of Kozak (2004)-2 showed consistent performances and was superior to other taper models in predicting diameter and volume. Conclusion: Based on the evaluation statistics of fitting and validation,graphic analysis and condition number,the model of Kozak (2004)-2 was recommended for estimating diameter at a specific height,total volume and merchantable volume for B. platyphylla in northeast China.

Objective: This study was implemented to explore the potential of deep convolutional neural networks in airborne hyperspectral data classification,so as to improve the classification accuracy of forest tree species in subtropical regions. Method: The aeronautical hyperspectral data of Nanning Gaofeng forest farm in Guangxi Zhuang Autonomous Region obtained by the LiCHy system of Chinese Academy of Forestry was used. The CNN model used in this paper aimed to deal with hyperspectral image analysis problems in an end-to-end manner. It could take raw data as input,without dimension reduction or feature screening,eliminating the need for traditional classification methods to manually feature selection in different degrees. The 3D convolutional layers in the network could extract spectral features and spatial features simultaneously,learn the local signal changes in the spatial and spectral dimensions of the feature cube,and classify them with important recognition features to improve the discriminating ability of hyperspectral images. For the problem of high dimensionality of airborne hyperspectral data and relatively few training samples,the CNN model was optimized to avoid over-fitting. Result: Compared with the traditional feature selection and object-oriented segmentation method,CNN could obtain a higher classification accuracy,the overall accuracy reached 98.38%,Kappa coefficient was 0.98. Compared with support vector machine combined with random forest (RF) feature selection classification,the overall accuracy was improved by 8.82%,and the Kappa coefficient was increased by 0.11. In the case of small sample training (75% reduction in training samples size),the overall accuracy still reached 95.89%,and the Kappa coefficient was 0.94. Conclusion: The three-dimensional convolutional neural network could fully utilize the rich information in the image processing of the feature extraction and classification of airborne hyperspectral imagery,which could achieve high-precision discrimination of subtropical forest tree species; in addition,reasonable network structure and training strategy (adding the Dropout layer) could greatly improve the network training speed and still get good results in small sample training,and could achieve efficient and accurate classification of forest species.

Objective: This study aims to provide theoretical basis on pathogenicity mechanism of Larix olgensis with pine wilt disease,and give some advice on pine wilt disease control in northern China. To this end,we investigated the pathogenicity and migration of pinewood nematode (PWN)Bursaphelenchus xylophilus in L. olgensis and the activity changes of superoxide (SOD) in L.olgensis after being inoculated with PWNs. Method: Two-year-old L. olgensis seedlings were inoculated sepa rately with three different isolates of PWN(QH-1,NM-1,and CM-1),the number of inoculation was 2 000 nematodes per seedling. After then,the pathogenicity,the external symptom and the nematode migration were observed daily. The stems segments with the same length above and below the inoculation spot(1.5 cm) were cut down in 1,2,4,7,10,15,and 25days after the inoculation,the cross-section was observed for detecting the disease occurrence and the migration of PWNs. Leaves were collected every day till 7days after inoculation,to analysis the change of SOD activity in L. olgensis. In 35 days after the inoculation,the morbidity was recorded and PWNs were extracted separately from wilt seedlings. The pathogenicity and migration of QH-1,NM-1,and CM-1 PWN in L. olgensis seedlings and the change of SOD activity in L. olgensis were analyzed. Result: L. olgensis seedlings were all wilt after inoculation with QH-1,NM-1 and CM-1 PWNs,but QH-1 PWNs caused seedlings to wilt 5days earlier than NM-1 and CM-1 PWNs. In 35 days after the inoculation,the morbidity rates of seedlings inoculated with QH-1,NM-1,and CM-1 PWN were 100%,70% and 60%,respectively,and the disease-infected indices were 100,43.3 and 40,respectively. The number of PWNs of QH-1 treatment was significantly greater than that of NM-1 and CM-1 treatments(P < 0.01). The migration ability of PWNs after inoculation showed the difference among QH-1,NM-1,and CM-1,and the migration ability of QH-1 was higher than that of NM-1,and CM-1. The change of SOD activity in L. olgensis showed the difference over QH-1,NM-1,and CM-1 PWN treatments,and the increase degree and decrease degree of QH-1 treatment were greater than those of NM-1 and CM-1 PWN treatments. The observation of cross-section showed that browning of pith and cavitation of xylem occurred at the early stage,and the QH-1 PWN treatment caused more serious damage than NM-1 and CM-1 PWN treatments. Conclusion: According to the external symptoms and the morbidities of seedlings,the migration of PWNs,the change of SOD activity,and the investigation of the cross-section,the three isolate PWNs all can cause wilt to L. olgensis seedlings,and the QH-1 PWN is more virulent than NM-1 and CM-1 PWN. Some of the inoculated seedlings had no obvious disease,but a small number of nematodes could be isolated,which indicates that the wilt of L. olgensis is related to the migration ability and fertility of the PWN inside L.olgensis.

Objective: This study aims to investigate the sources of the proctodeal trophallaxis substances of Reticulitermes chinensis,and provide reference for further study on the mechanism of trophallaxis and control of the termite. Method: The morphological changes of the alimentary canal in different types of individuals were compared by microanatomy. The contents of protein in the paunch (P3) and colon (P4) + rectum (P5) in different instar workers were measured,and the sources of the proctodeal trophallaxis substances of R. chinensis were determined. The relationship between "provider" and "recipient" of different instar workers in the proctodeal trophallaxis was inferred by counting the proportion of different instar workers in different nests. Result: 1) The P3 of the queen was the most developed among different types of individuals and its contents were viscous and yellowish brown color. The P3 of the worker was relatively developed and its contents were viscous and yellowish brown color. The P3 of soldier was also relatively developed and its contents were thick and white color. The P3 of 3^rd instar larva was still at the early stage and its contents were thick and white color. The contents of P3 were sticky and light yellow color in alate. 2) The P1,P4 and P5 of workers,soldiers,alates and queens were all similar in size with each other,suggesting that there is little relationship between the sources of the trophallaxis substances and the sizes of P1,P4 and P5. There was no significant difference in the size of the P3 among workers,soldiers and queens,but the color of the contents was obviously different. Thus,the color of the contents in P3 could be used as a morphological index to judge the "provider" or "recipient" of proctodeal trophallaxis. 3) In 2^nd-6^th instar workers,the protein content of P3 was higher than that of P4+P5,respectively. It was suggested that protein content in different parts of hindgut could also be used as a judging index of the trophallaxis substances origination. (4) The 2^nd-3^rd instar workers accounted for more than 50% of the total number of workers. With the development of colony,the proportion of the 4rd instar worker increased slightly. Conclusion: P3 is the main source site of the proctodeal trophallaxis substance. The 2^nd and the 3^rd instar workers are the main "provider" of proctodeal trophallaxis substances.

Objective: Gut microbiota can help host insects to degrade indigestible ingredients and harmful substance in food. The ability to digest and utilize the leaves of Eucomnia ulmoides in Orthosia songi (Lepidoptera: Noctuidae) larvae may be related with gut microbiota. Therefore,this study aims to investigate the gut bacterial composition of larvae in O. songi,so as to reveal the effects of intestinal bacteria on the growth and development,food digestion,nutrition utilization of host insects. Method: The traditional methods of microbial isolation and culture and the sequencing of 16S rRNA gene were used to isolate and identify the gut bacteria from the larvae. The dinitrosalicylic acid (DNS) and HPLC methods were used to verify the degradation of biomacromolecules (cellulose,pectin and starch) and chemical substances in leaves of Eucommia ulmoides by gut bacteria. Then the effects of gut bacteria on the growth and nutritional utilization of larvae were investigated by feeding 1 μg·mL^-1 chloramphenicol,an antibiotic. Result: Ten different bacterial strains were isolated from the larval guts by traditional microbial isolation and culture methods,and their DNA sequences showed that they belonged to ten genera in Proteobacteria,Firmicutes and Actinobacteria,including Brevundimonas,Enterococcus,Pseudomonas,Sphingomonas,Kluyvera,Acinetobacter,Moraxinella,Agrobacterium,Microbacterium, and Arthrobacter. These strains were able to cause degradation to biomacromolecules (cellulose,pectin and starch) in varying degrees,and affect the changes of some substances in Eucommia ulmoides leaves. The feeding test with 1μg/mL chloramphenicol affected the growth and development of larvae,and significantly reduced the pupation rate of larvae and the feeding and digestive ability of the younger larvae. Conclusion: Ten bacterial strains were isolated from the larval guts of O. songi,and they play important roles in the growth and development,food digestion and nutrient utilization of O. songi larvae.

Objective: The purpose of this work is to understand the habitats selection and spatial distribution of main pheasant species in Fanjingshan National Nature Reserve during breeding period and provide scientific basis for effective management of rare pheasants. Method: From April to July during the breeding season of pheasants from 2017 to 2019,60 camera traps were set up in 3 sample regions (20 cameras in each sample region) to monitor the pheasants living in the area. The habitats selection patterns of four species of pheasants were studied based on occupancy modelling. Result: 1) A total of 882 independent valid photos were obtained by infrared camera. Seven species of pheasants were recorded,including Syrmaticus ellioti,Bambusicola thoracicus,Tragopan temminckii,Chrysolophus pictus,and etc. 2) The results of occupancy modelling showed that altitude was the major factor affecting the occupancy rate of the four main pheasants,and the pheasants had different altitudinal distribution patterns. The occupancy rate of Syrmaticus ellioti,Bambusicola thoracicus,and Chrysolophus pictus were negatively correlated with the altitude (Bambusicola thoracicus mainly lived at altitude below 1 100 m; Syrmaticus ellioti mainly lived at altitude below 1 500 m; Chrysolophus pictus have adapted to life at different elevation). However,the occupancy rate of Tragopan temminckii,who actively lived at altitude above 1 500 m,was positively correlated with the altitude. 3) The four main species of pheasants showed two different patterns of vegetation type selection. Bambusicola thoracicus and Chrysolophus pictus were obviously inclined to choose coniferous and broad-leaved mixed forest for habitat,and obviously not preferred to choose evergreen and deciduous broad-leaved mixed forest; while Syrmaticus ellioti and Tragopan temminckii were inclined to choose evergreen and deciduous broad-leaved mixed forest,and obviously not preferred to choose coniferous and broad-leaved mixed forest. Meanwhile,as for the selection of slope,Syrmaticus ellioti and Tragopan temminckii had similar selection pattern in which the habitation was positively correlated with the slope index; Bambusicola thoracicus and Chrysolophus pictus,on the other hand,showed a different pattern in which the habitation was negatively correlated with slope index. Conclusion: In this study,the habitat selection and spatial distribution differences of four species of pheasants were studied by using the occupancy modelling in Fanjingshan Nature Reserve. The results preliminarily revealed the coexistence pattern of the four main pheasants during breeding period.

Objective: This study aimed to understand the reproductive traits and estimate the current population size of the endangered Crested Ibis (Nipponia nippon), so as to provide a scientific basis for the population status assessment and efficient conservation and management. Method: We investigated the nest sites of wild Crested Ibis in Yangxian and the surrounding area of Shaanxi Province and the environmental factors and reproductive parameters of each nest from March to June, 2019, and analyzed the nesting success and breeding productivity. Meanwhile, a simultaneous survey at the nocturnal roosts was conducted in September 2019, to investigate the population size and age structure. According to nest-site density, a fixed Kernel method in ArcView GIS 3.3 was used to estimate the distribution and area of three different nesting ranges, and Crosstabs and ANOVA in SPSS 22.0 were used to compare the differences of reproductive traits. Result: A total of 449 nest sites were recorded in 2019, which mainly distributed in Yangxian (66.8%) and Chenggu (29.0%). Based on Fixed Kernel estimation, the size of core nesting range and regular nesting range of Crested Ibis were 244.1 km² and 1 523.7 km², respectively, with the nesting density in core range of 0.73 nests·km^-2, which was much higher than that in regular range with 0.16 nests·km^-2. The nesting success rate averaged 66.4%, and it increased from core range, regular nest range to peripheral nest range, and the difference was significant among the three nesting ranges. The breeding productivity averaged 2.05, and it was significantly higher in peripheral nesting range than that in the other two nesting ranges. A total of 19 species of nesting trees were recorded, dominated by Pinus spp. (30.2%), Ulmus pumila (28.6%) and Populus davidiana (26.6%). There was no significant difference of nesting success among the three tree species, but the breeding productivity in Pinus spp. was significantly higher than that in the other two species. A total of 2 571 individuals were recorded in 38 nocturnal roosts, among which Yangxian and Chenggu counties accounted for 73.7% and 15.8% of the total roosts, respectively, and 73.0% and 23.4% of the total number of birds, respectively. The fledglings accounted for 11.6% of the total population. Conclusion: The wild population of Crested Ibis is increasing steadily, and the most of the nest sites and nocturnal roosts are still distributed in Yangxian and Chenggu. However, the population growth in the core nesting range may have been experiencing the suppression from the environment capacity, and consequently the population is accelerating its dispersal outside. The age structure of wild population is changing, which will have impact on the population growth rate. It is crucial to facilitate the habitat restoration in the core ranging and efficient management of peripheral population.

Objective: This current study was carried out to investigate the effects of different drying method on drying characteristics with the aim to provide theoretical bases for the high temperature energy-saving and green drying of plantation-grown Pinus sylvestris var. mongolica. Method: Four drying methods including conventional drying, high temperature drying, solar-conventional joint drying and solar-high temperature joint drying were used to study the drying characteristics of P. sylvestris var. mongolica focusing on drying time, drying rate, drying quality, drying energy consumption, etc. Result: The results showed that the drying characteristics of wood varied greatly with different drying methods. 100 ℃ showed that the comprehensive drying characteristics of P. sylvestris var. mongolica were grade 1. Moisture content of solar energy pre-drying wood was reduced from 80% to 30%, drying time was about 78 h, daytime drying speed was about 1.07%·h^-1, night drying speed was about 0.36%·h^-1. In the early and middle stages of drying, the drying speed of high temperature drying was higher than that of conventional drying by 136.15% and 113.30%, respectively, and only about 20.87% higher in the latter stage drying. The time of solar-conventional and solar-high temperature joint drying were 92 h and 86 h, respectively, which was about 3-5 times of conventional and high temperature drying. The wood drying quality after conventional drying was grade 1, and after high temperature drying was grade 2. The wood drying quality after solar energy joint drying was grade 3. High temperature drying made the wood color changed severely, turning dark yellow/dark yellow. Compared with conventional drying, high temperature drying could save 48.53% energy. Compared with conventional drying and high temperature drying, solar-conventional joint drying could save 40.09% and 17.08% energy, solar-high temperature joint drying could save 68.76% and 57.76% energy. Conclusion: The high temperature drying of P. sylvestris var. mongolica presented a good drying effect. Solar predrying could save a lot of energy consumption, whereas the joint of solar energy and high temperature drying could show efficient and green drying.

Objective: The desiccator method is one of the main methods to determine formaldehyde emission in wood-based panels. However, the desiccator method also has some problems such as poor reproducibility and low accuracy. In order to improve the accuracy of the measurement results, it is necessary to study the main influencing factors and measurement uncertainty of the desiccator method. Method: In this paper, veneer particleboard was used as the research object, the influences of water absorption and panel's loading rate on the determination of formaldehyde emission in panel by desiccator method were investigated. Meanwhile, the sources of various uncertainties in the determination processes of desiccator method were analyzed, and the uncertainty was also calculated. Result: When the water absorption increased from 20 mL to 300 mL, the stable release value of formaldehyde increased from 49 μg to 72 μg. When the load-carrying ratio of sheet metal increased from 0.037 m²·m^-3 to 17.6 m²·m^-3, the stable release value of formaldehyde decreased from 2.14 mg·L^-1 to 0.88 mg·L^-1 at unit load-carrying ratio. Furthermore, the uncertainty of the 40 L dryer method was higher than that of the 9-11 L dryer. Among the main sources of uncertainty, the uncertainty introduced by repeated measurements contributed the largest to the overall uncertainty. Conclusion: Absorbed water was positively correlated with formaldehyde emission, while carrying capacity was negatively correlated with formaldehyde emission. In the processes of experiment, each step should be operated according to the standard specification to ensure the accuracy and reliability of the data.

Objective: This research was implemented to study the influences of different laminate thicknesses of Chinese fir (Cunninghamia lanceolata) on the mechanical properties of cross-laminated timber (CLT), and to expand the application range of Chinese fir in the field of wood structure construction and further promote the development of CLT in China. Method: Under the premise that the overall thickness of the domestic Chinese fir CLT remains unchanged, the effects of different layer thicknesses on the CLT bending and shearing properties were studied. Combined with the bending test results, the existing CLT statics analysis theory was used to perform the above tests on the CLT specimens. The bending performances under different conditions were also calculated and compared. Result: Under the premise of an unchanging total thickness, bending stiffness of the three-layer CLT specimens was the highest, and the five-layer and seven-layer specimens were reduced by 11% and 18%, respectively. The bending strength of the five-layer CLT specimens was increased by 18% compared with the three-layer specimens, which was 36% higher than that of the seven-layer specimens. The shear strength of the five-layer specimens and the seven-layer specimens was increased by 2.6% and 16%, respectively, over the three-layer specimens. The trend of the theoretical analysis of the bending stiffness was the same as the test results, however, the theoretical analysis of the bending strength showed that the higher the number of layers, the higher the value, the test results showed that the five layers were better than the seven layers. When the five-layer specimens was taken as an example, under the premise of overall thickness unchanged, increasing odd and even layer thickness ratio could effectively improve the bending and shear properties of CLT specimens in a certain percentage range. Theoretical analysis had the same trend as the experimental results. Conclusion: The results showed that under the premise of overall thickness unchanged, the thicker the CLT laminated, the better the bending stiffness was, the worse the shear properties presented, and the single failure mode was. The 5-layer CLT specimen had the best bending strength; within a certain ratio range, increasing the ratio of odd and even layer thickness could effectively improve the bending and shear resistance of the CLT specimen.

Genomic selection was supposed to be the key technology and hotspot of those studies on animal and plant genetic breeding. Some progress has been made toward the genetic improvement of some animal and plant species. The breeding cycle of tree species is long due to their long generation interval. Early selection is an effective way to shorten the breeding cycle of trees and speed up the breeding process. The studies of early selection of trees can be roughly divided into three stages, including early selection based on the correlation between the early and late trait values, molecular marker-assisted selection and genomic selection. The growth and wood quality traits, the main target traits for tree genetic improvement, are often complex traits controlled by quantitative traits. During the constant process of tree growth and development, these traits are suffered from the on-going influence of the environment. Meanwhile, the heritability of these traits may be gradually changing in the process of tree growth and development. However, the application of genomic selection in tree genetic improvement was limited by the unique characteristic and weak research basis of perennial tree species, such as long generation interval, large body size, long juvenile phase, the lack of multi-omics data (genomic and phenotypic data), and the imperfection of technology platform to facilitate tree researches. To speed the application process of genomic selection in forest genetic improvement, this paper attempts to provide a short overview of the principles and method of whole genomic selection, to summarize recent progress of genome-wide selection in forestry tree genetics and breeding, and to discuss the constraint factors which impact the application of genomic selection in forestry tree genetic improvement. The paper provides a brief introduction of the linear model, statistical estimation methods (SNP-BLUP, GBLUP & Bayesian) and analytical tools (rrBLUP, synbreed, BGLR, GVCBLUP, GAPIT, sommer, BLUPGA and so on) used for genomic selection. It summarizes the advantage of genomic selection applied in forestry tree breeding and the studies of using genomic selection in both broadleaf Populus, Eucalyptus, Elaeis & Hevea) and coniferous (Pinus & Picea) tree species, and dissects these reports of genomic selection in Elaeis guineensis as typical cases. These studies of genomic selection in forestry tree species show that genomic selection contributes to improving the efficiency of forest selection and to accelerating tree breeding. It discusses in detail the possible influence of the tree reference genome, the genome-wide association study, the breeding population, the linkage disequilibrium and the perennial attribute on the genomic selection of trees. Genomic selection has potential application prospects in tree genetics and breeding research. Nevertheless, its feasibility still needs to be further evaluated using vast amounts of simulated and real data. The current research on tree genomic selection is facing multiple challenges: 1) a relatively low quality of genome assembly for tree species, 2) genomic selection for simultaneously screening multiple target traits, 3) the designing of the rational experimental scheme according to the characteristics of the perennial tree species, and the development of the statistical model and analytical tool capable of analyzing the longitudinal character data.

Objective: Through the establishment of global forest product space to test whether there is a dynamic correlation between the spatial structural change of global forest products and the dynamic evolution of comparative advantage, this paper attempts to make a preliminary analysis of the cultivation target of China's comparative advantage of forest products from the perspective of microcosmic product. Method: Based on the theory of product spatial structure, the global forest product space was constructed. Using the forest product trade data of 43 major forest product trading countries from 1992 to 2017, the R software was used to measure the proximity between two forest products in 72 forest products, and the heterogeneity structure of global forest product spatial distribution was verified, and a high dimensional panel data model was established to further examine the relationship between the spatial distribution structure of global forest products and the dynamic evolution of comparative advantage of a country's forest products; On this basis, the density of forest products with potential comparative advantage was ranked to choose the cultivation goal of the comparative advantage of China's forest products trade. Result: From the perspective of the spatial composition of global forest products, the wood products and furniture are mainly in dense areas; Non-wood forest products are not found in the top 10 products in the dense area, but in the sparse area, the ten commodities are non-wood forest products except recycled paper and wood pulp products; There is a significant positive correlation between product density and product comparative advantage, which is stable in time series. In the future, the possibility of conversion from forest products in comparative disadvantage to comparative advantage will be gradually reduced from high to low according to the ranking of product density. Conclusion: The distance between two forest products in the global forest product space is not equal, and the global forest product space is heterogeneous and unbalanced; The closer the distance between the forest product with potential comparative advantage and the existing comparative advantage product set, the easier it is to realize the transformation from potential to actual comparative advantage; Ranking the density of forest product comparative disadvantage can guide the trade of forest products for government or competent authorities, combine the comprehensive practice of forest product trade of China and the environmental changes of global forest product trade, and finally achieve the policy objectives through the cultivation of comparative advantage forest products; The spatial structure of global forest products is closely related to the change of comparative advantage of forest products. If the competent authority or policy-making department follow this inherent law to guide the changes in the comparative advantage of its forest products, it would have a better policy effectiveness.

objective: This paper aims to study the diversity of urban riparian forests in Beijing and explore the regularity of gradient changes in the diversity of plant populations in order to provide a basis for the construction of close-to-nature riparian plant community. Method: Urban rivers of different scales within the sixth ring road of Beijing were divided into 337 river segments through field investigation. 575 transects in size of 400 m² were set up to investigate the species names and quantity of arbors and shrubs. Statistical analyses were carried out to compare the changes of diversity of urban riparian forests among different ring roads, different scales of rivers and different hardening-degree river banks. Result: there are 119 species, 75 genera, 40 families of urban riparian forest in Beijing, including 82 species, 49 genera, 31 families of arbors and 37 species, 28 genera, 14 families of shrubs; the Margelf index of urban riparian arbors was ranked as 5th-6th ring road > 2nd-3rd ring road > within 2nd ring road > 3rd-4th ring road > 4th-5th ring road, while the Margelf index of shrubs was ranked as 2nd-3rd ring road > 5th-6th ring road > 4th-5th ring road > within 2nd ring road > 3rd-4th ring road; the Shannon Wiener indices of urban riparian forest in different river gradients presents first-grade river > third-grade river > second-grade river, while the Shannon-Wiener index of shrub displayed opposite orders.4)the Magnelf index, the Shannon-Wiener index and the Pielou index of close-to-nature river bank are the largest among banks with different hardening gradients, while the diversity index (except evenness index) of shrub in the vertical dam bank isthe largest. Conclusion: The level of diversity of urban riparian forest in Beijing is generally low. With the increase of the distance from the city center, it shows a trend of increase-decrease-increase, which is consistent with the change trend of undergrowth shrubs. The trend of arbor-bush diversity of riparian forest in different river grades is different, and the arbor species diversity level is generally higher than that of shrubs. The overall level of tree diversity is higher than that of shrub. The arbor species diversity index is higher in close-to-nature river bank, while the undergrowth shrub diversity index is lower. We should make more use of the reasonable plant community structure of typical vegetation of arbor and shrub to improve the diversity level of urban riparian forest in Beijing.