Objective: The objective was to stratify the arbor trees of a mid-subtropical forest community with a single dominant species of Castanopsis kawakamii, in order to provide a precondition for further study of the characteristics and dynamics of each layer. Method: Two sample plots in a size of 50 m×50 m of C. kawakamii forest community located in the provincial nature reserve of C. kawakamii were investigated respectively using the methods of maximum light receiving plane (MLRP), profile diagram, and model-based clustering (MCLUST) to stratify the forest community of the two sample plots. Result: The two sample plots were all closed forest stands and the canopy density were all more than 0.95. In sample plot 1, the stand density and volume were 424 trees·hm² and 588.04 m³·hm², and the average DBH was 39.2 cm, the average tree height was 26.69 m. In sample plot 2, the stand density and volume were 542 tree·hm² and 417.19 m³·hm², and the average DBH was 29.1 cm, the average tree height was 26.69 m. All the three methods can solve the problem of stratifying the arbor layer, but MLRP method was the optimal because it is relatively simple and convenient with less field work and having explicit biological interpretability. According to the MLRP, the arbor layer of the C. kawakamii forest community should be divided into two sub-layers which were consistent with the results of the profile diagram and the MCLUST. The upper layer was light receiving layer (LRL) and the lower layer was none-light receiving layer (NLRL). The thresholds between LRL and NLRL of the two sample plots were 16.00 and 16.90 m. In sample plot 1, the ratio was 6:4 for counts of trees of LRL and NLRL, and 99:1 for volume. In sample plot 2, the ratio was about 3:7 for counts of trees of LRL and NLRL, and 97:3 for volume. In sample plot 1, C. kawakamii distributed in LRL accounted for 40.6% of the total number of trees in the arbor layer and 76.9% of the total stand volume; in NLRL that were 3.8% and 0.4%. As to sample plot 2, C. kawakamii in LRL accounted for 27.0% of the total number of trees, and 84.1% of total stand volume; in NLRL that was 5.7% and 0.2%. Conclusion: The MLRP method is more suitable than the other two methods for stratifying the arbor layer of the C. kawakamii community. Both communities can be divided into LRL and NLRL. C. kawakamii is absolutely dominant in terms of number of trees and the volume in LRL but not NLRL. This vertical distribution pattern implies in sufficient regeneration and recruitments under forest, which can be a limitation for the sustainable development of C. kawakamii population. Further studies are needed to characterize the layers and their relationships, as well as the dynamics of formation and development of the layers, providing scientific basis for the protection of natural C. kawakamii forests.

Objective: This study aimed to provide a theoretical basis for understanding the characteristics of water use of trees and the response mechanisms to environment through measuring the characteristics of diurnal and nocturnal sap flow of Populus×euramericana cv. '74/76',quantifying the contribution rate of nocturnal sap flow to the daily sap flow,and investigating the response difference of diurnal and nocturnal sap flow to tree dimensions and environmental factors. Method: In this study,P.×euramericana cv.'74/76' was used as the research object,which is a common afforestation tree species in northern China,The experiment was conducted in the Binhe forest park of Shunyi new city,Beijing. Thermal dissipation (thermal dissipation probe,TDP) technique was used to continuously monitor the sap flow of P.×euramericana cv.'74/76',sunny day data were selected and calculated based on measuremnts of the individual plant of small,medium and large diameter of P.×euramericana cv.'74/76',and simultaneously the data of environmental factors were collected. Result: 1) The sap flow velocity of the small,medium and large diameter of P.×euramericana cv.'74/76' all showed a single peak curve with the diurnal sap flow high and nocturnal sap flow low. The first half of the nocturnal sap flow was more active than the second half. 2) During the period from July to October,the daily sap flow over all diameter classes ranged from 39.04 to 94.96 g·cm^-2d^-1,and the nocturnal sap flow was between 3.34-10.49 g·cm^-2d^-1. The contribution rate of nocturnal sap flow to the daily sap flow of all diameter classes was between 4.2% and 16.2%. There was significant difference between the daily sap flow and the diurnal sap flow (difference between the daily sap flow and the nocturnal sap flow from) (P < 0.01). 3) The responses of diurnal and nocturnal sap flow to tree dimention were consistent,and the canopy size was significantly (P < 0.05) correlated with diurnal and nocturnal sap flow in P.×euramericana cv.'74/76',and the interpretation of diurnal and nocturnal sap flow was 80% and 77%,respectively. Tree height and diameter at breast height had no significant effect on diurnal and nocturnal sap flow (P>0.05). 4) On the daily scale,vapor pressure deficit (VPD),global radiation (R_a),air temperature (T) and wind speed (W_s) were the main environmental factors affecting the sap flow of P.×euramericana cv.'74/76'. There were differences in the environmental influence factors influencing diurnal and nocturnal sap flow velocity. VPD,R_a,T and W_s were the main environmental factors affecting diurnal sap flow velocity,while nocturnal sap flow velocity was mainly affected by VPD and W_s. The effect of W_s on diurnal and nocturnal sap flow velocity was two fold,which was characterized by promoting diurnal sap flow velocity and inhibiting nocturnal sap flow velocity. Diurnal sap flow was extremely significantly positive correlated nocturnal sap flow (P < 0.01). The diurnal sap flow of the small,medium and large diameters explained 37%,48% and 47% of the nocturnal sap flow,respectively. Conclusion: There is obvious nocturnal sap flow in P.×euramericana cv.'74/76'. When estimating the water consumption of P.×euramericana cv.'74/76',if the nocturnal sap flow is neglected,the daily water demand of P.×euramericana cv.'74/76' will be underestimated. There is difference in the response of P.×euramericana cv.'74/76' sap flow velocity to environmental factors during the day and night,when estimating and simulating tree transpiration,we should consider the effects of diurnal and noctural environmental factors on sap flow velocity separately.

Objective: In this study the critical moisture content of embryo axis of recalcitrant seed Castanea mollissima was studied,the seed cooling preservation technique and embryo axis cryopreservation technique were explored in order to provide scientific basis for the preservation of recalcitrant seeds in seed bank of chestnut and other recalcitrant forest trees. Method: Chestnut embryo axes were cut from the seed and subjected to rapid dehydration with silica gel to target moisture content,after which the germination rate of embryo axes at different moisture content was determined. Differential scanning calorimetry (DSC) was used to determine the thermodynamic characteristic parameters of embryo axis at different moisture content. According to the relationship between embryo axis moisture content and corresponding enthalpy,the critical moisture content of Chinese chestnut was calculated. Finally,the chestnut seeds were preserved at low temperature with the method of low temperature sealing preservation. The embryo axis cryopreservation of Chinese chestnut with different moisture content was determined by direct freezing,programmed freezing,vitrification freezing and programmed vitrification freezing. Result: 1) When the embryo axis moisture content decreased to 20%,the germination rate began to decline. When the embryo axis moisture content decreased to 10%,the germination rate decreased to 25.6%. 2) The DSC results showed that the onset temperature of crystallization,peak temperature and enthalpy were all decreasing with the decrease of embryo axis moisture content,and there was a significant positive correlation between them.When the embryo axis moisture content dropped to 25%,the onset temperature of crystallization drops to -37.2℃,the peak temperature dropped to -44.1℃,and the enthalpy value was 5.0 J·g^-1 dw.When the embryo axis moisture content decreased to 20%,no peak appeared in cooling crystallization and heating melting stages. 3) Base on the embryo moisture content and corresponding enthalpy,the critical moisture content of this chestnut variety was 23.9%. 4) Chestnut seeds were sealed and stored in a low temperature environment of 2℃,there was no significant change (P>0.9) in germination rate chestnut seeds and shoot lengths and root lengths of chestnut seedlings after 6 months storage. 5)Among the four cryopreservation methods,vitrification and programmed vitrification had higher embryo axis germination rate than direct freezing and programmed freezing,and the best method was programmed vitrification freezing. Conclusion: Chinese chestnut is a typical recalcitrance seed,and the embryo axis moisture content decreased to 20% or less will affect the germination activity of the embryo axis. Based on differential scanning calorimetry technique combined with embryo axis germination test of different water contents can effectively determine the critical water content of this chestnut variety of 23.9%. Chestnut seeds can be preserved more than 6 months under low temperature (2℃) with no significant change in germination rate and shoot lengths and root lengths. The embryo axis germination rate of chestnut can be improved after cryopreservation by adding PVS₂.

Objective: Secondary laticifer in the trunk of a rubber tree (Hevea brasiliensis) is the major tissue to synthesize and store the natural rubber. The number of secondary laticifer rows has a significantly positive correlation with the rubber yield,and further,the differentiation of the secondary laticifer can be induced by mechanical wounding in both mature tree trunk and tender shoot. Wickham germplasm,as the key source of cultivars,little is known about the secondary laticifer differentiation of shoots responded to the mechanical wounding. In the present study,the differentiation characteristics of different Wickham germplasm shoots were studied,in order to provide early prediction of the capacity of the secondary laticifer differentiation after tapping of mature trees,and to provide a basis for identification and evaluation of the germplasm resources,and further to shorten the time needed for breeding,therefore to improve the efficiency of Hevea breeding. Method: A total of 304 accessions of Wickham germplasms were selected and treated with mechanical wounding by using a blade to scrape the tender shoot deep to the cortex. Fresh bark samples were separately collected at 5 days and 10 days after wounding,then treated with iodine-bromine reagent,and embedded in paraffin. The differentiation of the secondary laticifers were observed with an optical microscope and data on time of emergence and number of the secondary laticifers were recorded for statistical analysis. Result: There was a significant difference of secondary laticifer differentiation among the 304 different accessions of Wickham germplasms induced by mechanical wounding. 5 days after wounding,secondary laticifer(SL) were clearly formed in rows in 95 accessions of the germplasms,sparse SL cells not in rows were found in 172 accessions of the germplasms,and no SL was detected in the other 37 accessions. 10 days after wounding,however,up to 265 accessions of the germplasms displayed clear SL rows,of which 22 accessions had 2 or more SL rows. Accordingly,the number of germplasm accessions with sparse SL and no SL reduced to 37 and 2 respectively. Undoubtedly,the induction ratio of SL differentiation in the 304 germplasm accessions at 10 days was obviously higher than that at 5 days. In different breeding series,the Dafeng,Baoting,Reyan,and Daling that derived from Hainan showed a better differentiation effect. According to the sensitivity and intensity of the SL differentiation,the Wickham germplasms were classified into 4 types:sensitivity type,sensitivity-sustainability type,hysteresis type and hysteresis-sustainability type,among which the sustainability types were always the high-yield germplasms. Conclusion: Different Wickham germplasm accessions had different characteristics of SL differentiation responded to mechanical wounding. 5 days and 10 days after wounding can be used to select the sensitive and the hysteretic germplasms respectively. Among the 4 types of the Wickham germplasms,the sustainability type is the main source for superior varieties. The ability of high SL differentiation of epicormic shoot induced by wounding can be used as an effective indicator for early selection of high-yield Hevea trees.

Objective: This paper aims to determinate the light saturation point of biomass estimation using remote sensing data of Simao pine(Pinus kesiya var. langbianensis)forest, and construct the spatial global model and the local remote sensing information model, then inverse the biomass of Simao pine forest. The results will provide a reference for estimating biomass of Simao pine using remote sensing data. Method: This study calculated the light saturation point of Simao pine forest biomass using the quadratic term function and power function model based on Landsat8 OLI images, and the forest resource inventory data in 2016 of Pu'er city, Yunnan Province, were used to construct the remote sensing information model with the ordinary least square(OLS), spatial lag model(SLM), spatial error model(SEM)and geographically weighed regression(GWR), and then the aboveground biomass of Simao pine forest was estimated. Result: 1) The light saturation point of aboveground biomass estimated by Landsat 8 OLI remote sensing in Simao pine forest of Pu'er city was 106.3 t·hm^-2. 2) The highest coefficient of determination(R²=0.373)and the lowest Akaike information index(AIC=4 577.8)of GWR model indicated that it has the better fitting performance than OLS, SLM and SEM model. 3) The results of the independent sample test showed that the estimation accuracy of GWR model was higher than those of OLS, SLM and SEM model, especially at the high value stage (above 100 t·hm^-2) and the low value stage (below 50 t·hm^-2) based on the Jackknife method test. 4) The aboveground biomass by inversion using GWR model was 66.496 t·hm^-2, and its estimation error with the measured data was 23.511%, which was less than the estimation values of OLS, SLM and SEM model. Conclusion: GWR model is superior to OLS model and other spatial global regression models in estimating biomass of Simao pine forest in Pu'er city by remote sensing. Moreover, GWR model can solve the problems of high-value under estimation and low-value over estimation to a certain extent, and reduce the influences of the light saturation point on the accuracy of remote sensing estimation.

Objective: The study was conducted to perform the two-branch improvement on fully convolutional network models to explore a new method for the deep learning classification of remote sensing images of forest types with a high spatial resolution, with an aim to provide technical support for the improvement of the accuracy of remote sensing investigation of forest resources. Method: The two-branch FCN-8s contained two FCN-8s sub-models. One sub-model was constructed by fine-tuning based on RGB three-band features and the other sub-model was constructed based on five-band features. The sampling results of these two sub-models at 8, 16, and 32 magnifications were fused and classified to obtain the category of each pixel. Taking Wangyedian forest farm as the research area, the normalized difference vegetation index (NDVI) was extracted based on GF-2 satellite remote sensing images. In addition, the data set based on R+G+B three-band features, R+G+B + NIR four-band features and R+G+B + NIR + NDVI five-band features was constructed to evaluate the effectiveness of the two-branch FCN-8s optimization method quantitatively. Result: 1) The overall classification accuracy of the two-branch FCN-8s method is 85.89% and the Kappa coefficient is 0.84. Compared with the traditional FCN-8s, the dual-branch FCN-8s method can improve the classification accuracy of most forest types, especially for Chinese pine, Korean pine and white birch, and the improvement effects are significant. 2) Compared with the SVM model based on traditional features, the overall classification accuracy of the dual-branch FCN-8s method increaseds from 75% to 85.89%. The accuracy is improved by over 10%. The classification effects of each category are also improved. 3) With the fine-tuning strategy and NDVI features, the model can effectively improve the classification effects of Chinese pine, aspen and white birch. Conclusion: The deep learning precision classification method for forest types with dual-branch FCN-8s high-resolution remote sensing images can effectively improve the subdivision degree and the classification accuracy of forest types.

Objective: Changsha, Dalian, Nanchang and Shenzhen were selected to detect the spatio-temporal patterns of greenspace changes and main impact factors.This study aims to provide the new spatial data for the improvement of urban greenspace theories and models, and for the optimization of greenspace network. Method: Based on the time-series Landsat composites imagess, NDVI-thresholding technique was applied to reclassify greenspace into four categories and landscape indices were used to measure the characteristics of greenspace patterns. Temporal dynamics of greenspace was assessed using the Mann-Kendall trend test. Normalized distance index (NDI) was calculated to measure the urban-to-rural gradients. Dynamic time warping (DTW) was applied to detect the differences of long-term trends trajectories of landscape indices in four cities. Finally, maximum information-based non-parametric exploration method (MINE) was used to detect the pairwise relationships between the changes in greenspace patterns and main impact factors. Result: From 1985 to 2011, the percentage of dense vegetation in Changsha, Dalian, and Shenzhen had an average increase of 0.26% and the mean patch size of dense vegetation increased 0.11 hm². The percentage of medium-dense vegetation in these three cities had an average decrease of 0.40%, while the mean patch size in Nanchang and Shenzhen increased 0.15, 0.04 hm² respectively, however, Changsha and Dalian decreased 0.01, 0.08 hm² respectively. The percentage and mean patch size of sparse vegetation in Changsha and Nanchang showed an increase trend. The percentage increased by 0.12% and 0.23%, the mean patch size increased by 0.04 and 0.01 hm², respectively. To the contrary, the percentage of sparse vegetation in Dalian and Shenzhen decreased 0.22% and 0.63% while the mean patch size decreased 0.04 and 0.06 hm².The urban-to-rural gradients of dense vegetation in Changsha and Nanchang had a ∩-shaped trajectory. Sparse vegetation in Changsha and Shenzhen had a monotonic decreasing trajectory, while Dalian, and Nanchang had a ∪-shaped trajectory. The changes in greenspace patterns had strong non-linear relationships with income, gross domestic product per person, proportion of urban population and proportion of city area. Conclusion: From 1985 to 2011, the dense vegetation in Changsha, Dalian and Shenzhen increased and the patches became more connected, contrasting to medium-dense vegetations. In the four selected cities, sparse vegetation increased in inland cities and the patterns became less fragmented, contrasting to the coastal cities. There are three trajectories of urban-to-rural gradients of greenspace, the first one is parabola-shaped trajectory ("∩or∪"), second is constant trajectory ("-"), third is monotonic increasing or decreasing trajectory. The greenspaces tended to have large changes in the city centers and suburb areas.

Objective: In this study, based on computer image processing technology to extract insect image features, a new feature selection technique was proposed to screen features related insect identification. The technique is developed for accurately and quickly identifying the species of Lepidopteran insects. Method: In order to improve the universality of the model, the open-source Leeds butterfly dataset and the dataset of the forest Lepidopteran insects were used in this study. The improved texture feature extraction algorithm (DRLBP) was used to extract the texture features of Lepidopteran insect images to obtain high recognition accuracy. The hamming distance was used to calculate the distance between particles and measure the population diversity. A method of automatically adjusting the diversity in the evolutionary process was proposed. A binary adaptive differential evolution (BADE) algorithm was presented. The BADE algorithm were used to select the appropriate subset of texture features with small dimensions, and probabilistic collaborative representation based classifier (PROCRC) was used to classify images. Result: PROCRC classifier showed good classification result on all datasets. Its average recognition rate was 81.73% and 88.18% respectively. The classification accuracy of insects was significantly improved by feature selection. Its highest rate of improvement was 13.49%. The performance of BADE algorithm were better than other feature selection algorithms. The dimension and classification time of texture dataset selected by the BADE algorithm was significantly reduced. The dimensionality reduction rate was close to 50%, and the time reduction rate was up to 50%. Conclusion: The BADE algorithm proposed in this study can effectively carry out feature selection, which improves the recognition accuracy and saves the recognition time of the model. It is indicated that the method of feature selection for Lepidopteran insect images using swarm intelligence optimization algorithm is feasible. In summary, the method of recognition of Lepidopteran Insects combined with DRLBP and BADE algorithm is proposed in this study, which has important application prospects in rapid and accurate identification of agricultural and forestry insects.

Objective: In this study, we isolated and characterized the causal agents of witches' broom disease on 5 bamboo species of non-Phyllostachys, and analyzed the morphological features and culture characteristics of the pathogens, which would provide a scientific basis for identifying of the pathogen, controlling the witches' broom disease of bamboo, and determining the phylogenetic relationship of Clavicepitaceae. Method: The pathogens of witches' broom disease were isolated from the infected tissues of five bamboo species of non-Phyllostachys in Hangzhou of Zheijiang and Xishuangbanna, Yunnan through the conventional tissue isolation approach. The species identification was conducted based on morphological methods combined with molecular biology. The morphology and conidia size of the pathogens were determined by microscope, and the phylogenetic relationships of Clavicipitaceae were investigated based on the ITS rDNA and LSU rDNA sequences. Result: The morphological structure of the pathogens isolated from Semiarundinaria sinica, Bashania fargesii and Pseudosasa amabilis var. tenuis were similar to Aciculosporium take. The conidia of pathogenic fungus formed a pale yellow colony with uneven fold, slightly glossy surface and irregular edge on PDA plate. The conidia of pathogenic fungus was needle shape, (22.4-52.0) μm×(2.2-6.0) μm in size. The mycelia of pathogenic fungi isolated from the infected tissues of Dendrocalamopsis stenoaurita and Dendrocalamus strictus formed round colony with smooth surface and regular edge on PDA plate. The pathogen produced short rod-like conidia after 72 days of culture, and the size of the conidia was (5.4-10.5) μm×(1.2-2.8) μm. The sequence analysis and phylogenetic analysis based on ITS rDNA and LSU rDNA showed that the pathogenic fungus isolated from S. sinica, B. fargesii and P. amabilis var. tenuis were clustered with A. take with 99% bootstrap support, and the pathogenic fungus isolated from D. stenoaurita and D. strictus were clustered with Heteroepichloë bambusae with 100% bootstrap support. Conclusion: The causal agent of witches' broom disease of S. sinica, B. fargesii and P. amabilis var. tenuis is A.take, which is closely related to the genus Claviceps.The causal agent of witches' broom disease of D. stenoaurita and D. strictus. is H.bambusae, which is closely related to the genus Balansia, but distantly related to the genus Epichlo.

Objective: This study aims to elucidate the distribution regulation and relationship of competition and coexistence of three Tomicus minor, T. yunnanensis and T. brevipilosus (Coleoptera, Scolytidae) infesting Pinus yunnanensis shoots and trunks during the transferring stage from shoot to trunk, and provide theoretical support for population monitoring and integrated control of the three Tomicus species in the future. Method: Based on niche theory, the relationship between niche and population distribution of three Tomicus spp. feeding on P.yunnanensis during the transferring stage from shoot to trunk was studied by using sampling method with pruner in Xiangyun County, Yunnan province. Result: The peak time in both sexes of T. minor was later than that of T. yunnanensis in the crowns of P. yunnanensis, respectively, while there was no significant peak of T. brevipilosus. T. minor was distributed in the base of crowns, while T. yunnanensis and T. brevipilosus were distributed in the upper parts. In the early stage of invasion, T. yunnanensis was distributed in the whole stems of P. yunnanensis, and gradually distributed to the middle-upper part of stem as T. minor infested from the base to upper of stem. The population density of T. minor was significantly different in different heights of Yunnan pine trees, while that of T. yunnanensis was significantly different during the later stage of trunk-boring. There was significant difference in the temporal- and spatial- niche among the three Tomicus species, as well as between the sexes. The temporal-niche breadth in T. minor was more than that T. yunnanensi. On the contrary, the spatial-niche in T. minor was lower than that T. yunnanensi. Conclusion: T. minor and T. yunnanensis co-existed and homologously competed with each other through the allocation and compensation of spatial and temporal resources. The temporal resources in T. brevipilosus were separated from the former two beetle species.

Objective: In order to early warn stealthy wood boring pest, lightweight neural networks were designed and implemented in the present study, and the acoustics recognition technique was used to automatically identify larvae boring vibrations of Semanotus bifasciatus (Coleoptera:Cerambycidae) and Eucryptorrhynchus brandti (Coleoptera:Curculionidae). Method: The SP-1L piezoelectric vibration probe of the AED-2010L sound pick-up was embeded into the woods sections with larvae of S.bifasciatus and E.brandti, the boring vibrations were recorded by the sound recorder. The sounds of S.bifasciatus, E.brandti and no insect were preprocessed by endpoint detection algorithm and time warping algorithm to calculate the log mel-spectrograms. The log mel-spectrograms were then fed into the convolutional neural networks (CNNs). The boring vibrations were short impulses, thus their size was far smaller than that of images. In this paper the InsectFrames of a light-weight CNN were designed in order to prevent over-fitting of the mode. The insectFrames consisted of four convolutional layers using 3×3 kernels. Global average pooling was located before the connected layer, which can reduce parameters of network.The present study proposed four different CNNs which named InsectFrames_1-4 based on different feature interlayer dimensions and dimensionality reduction method. Result: The vibration identification method for identifying the two insect boring vibrations based on neural networks was able to efficently monitor the occurrence of forest boring insects early, and accurately identify the pest species.The sounds of S.bifasciatus, E.brandti and no insect were recognized using InsectFrames_1-4.The average accuracy on the test set reached more than 90%, and the average recognition time of CPU was about 0.1-1.3 s. Among them, model InsectFrame-2 was the best and its accuracy was 95.83%, and the accuracy was 34.2% higher compared to the Gaussian mixture model which is widely used for insect sound recognition.The accuracy increased by 6.94% compared to the heavy-weight ResNet18 model designed for image classification, and the time efficiency increased by more than 170 times. Conclusion: The proposed method applies neural network and sound identification technique to automatic monitoring of larvae boring vibrations, which can improve the early warning of forestry boring insects, and has the advantages of high efficiency, simplicity and low cost.

Objective: The effects of enzymatic hydrolysis lignin(EHL)mass concentration in tetrahydrofuran(THF)on the structure of lignin hollow nanoparticles(LHNPs)and the effects of the structure of doxorubicin hydrochloride(DOX)loaded LHNPs(DOX@LHNPs)on the drug controlled release behavior were investigated in this study, which might provide bases for selecting entrapment utilization of LHNPs in different fields. Method: LHNPs were prepared with dissolving different quality of EHL in THF and afterward dropping deionized water to the solution. EHL could be self-assembled into nanoparticles and loaded DOX- iniside LHNPs forming drug-loaded nanoparticles, by adding a certain quality of DOX to the mixed solution. The microstructure and particle size of the material were characterized by transmission electron microscope(TEM), scanning electron microscope(SEM), laser particle size analyzer(DLS)and surface area and a pore volume analyzer. Ultraviolet-visible spectrophotometer(UV-vis), X-ray diffractometer(XRD) and infrared spectrometer(FTIR)were performed to quantify the encapsulation and controlled release of DOX by LHNPs. Result: The value obtained by DLS showed that an increase of the pre-dropping lignin mass concentration from 0.3 to 3 mg·mL^-1 led to the nanoparticles size decreased from 552.6 to 266.8 nm, whereas the PDI values were basically stable. Additionally, the distribution for size of nanoparticles was uniform, which could be stored in water for more than 10 days. Moreover, the size of shells, surface area and pore volume were also decreased with the increase of pre-dropping lignin mass concentration. Hollow spherical structure of lignin nanoparticles with a hole on the surface was observed by TEM and SEM. The test result of UV-vis, XRD and FTIR showed that DOX could be loaded by LHNPs. The behaviors of DOX release were different in two pH systems. For the same test object, the drug released slightly rapidly in acidic(pH=5.5)condition comparing with in neutral(pH=7.4)condition. The larger specific surface area and porosity could improve the encapsulation ability of hollow nanoparticles for DOX, and the thicker shell particles had more stable controlled release result for DOX. Conclusion: The EHL could be microphase-separated in tetrahydrofuran and self-assembled into a dimensionally stable nano-scale surface with hollow spherical particles of a single pore. By controlling the initial mass concentration of lignin, it might be possible to obtain hollow particles of different diameters and shell wall thicknesses. For DOX@LHNPs, the larger the area and porosity is, the greater the drug loading. However, the hollow drug-loaded nanoparticles with more regular structure and thicker shell walls were beneficial to the stable release of DOX.

Mature forest is often referred to as the old-growth forest or the late-successional forest, which plays an important role in maintaining biodiversity and long-term carbon balance. In recent ten years, the carbon sequestration in mature forests under different environmental regimes and global change scenarios has received increasing attention since the founding that the old-growth forests can accumulate carbon in soils. Understanding the carbon storage and carbon source/sink dynamics of mature forests can be helpful for evaluating and predicting the role of mature forests in regional carbon cycles. It is also essential to evaluate the full range of forest C mitigation and to develop the close-to-nature forest management practices. On the basis of introducing the thresholds of mature forest ages, this paper analyzes the dynamics of carbon storage and distribution in natural mature forest, and the mature forest productivity and their influencing factors. Three carbon source/sink hypotheses of mature forest are summarized:1) The carbon neutral hypothesis proposes that net ecosystem productivity in forests steadily increases to a maximum with the age of forests, followed by gradual decline. The total ecosystem photosynthetic assimilation is increasingly offset by higher autotrophic and heterotrophic respiration at the mature forest stage, eventually, old forests are believed to reach (that is, C neutrality). 2) The carbon sequestration hypothesis suggests that many old-growth forest ecosystems in tropical, subtropical, and northern and temperate regions can continue to accumulate carbon, and act as a net sink for atmospheric carbon dioxide for centuries. The carbon sequestration in the mature forests is mainly in the soil, which is probably related to the increasing productivity of mature forests caused by climate change, and the increasing conversion of vegetation carbon into soil carbon with the increase of forest maturity, as well as the decreasing heterotrophic respiration in mature forest soil due to the global warming and atmospheric nitrogen deposition. 3) But very few studies have shown that the old-growth forests serve as a het carbon source. Accelerated carbon cycling of litters, dead trees, and soil organic carbon pools, especially when coupled with limited growth potential, could potentially drive the mature forest ecosystems to become a net source of carbon under future regional climate change scenarios. A growing number of studies have confirmed that the mature forests can sequester carbon, supporting the mature forest sink hypothesis. The future research should be focused on:1) Ttrengthening the carbon fluxes observation of mature forests by using eddy covariance approach. 2) Exploring the process of carbon source/sink and its formation mechanism in mature forest based on ecosystems respiration and its composition. 3) Studying the effects of global change on carbon sequestration in mature forests.

Lignocellulosic biomass is one of the most abundant renewable resources on earth. In order to improve the conversion rate of lignocellulosic biomass, increase the enzymatic hydrolysis efficiency of cellulose and the yield of fermentable sugars and to reduce the usage of cellulase and the conversion cost of biomass, it is essential to obtain the pretreated lignocellulosic biomass. However, the natural barrier between lignin, cellulose and hemicellulose limits the availability of cellulase to the cellulose components encapsulated inside. The main pretreatment methods of lignocellulose covered physical method, chemical method, physical chemical method and biological method. At present, the more adopted pretreatment methods include the dilute acid(hydrochloric acid, sulfuric acid, nitric acid, etc.)with the mass fraction less than 4% at the temperature of 120-210℃, high temperature hot water method, steam explosion method and liquid hydrothermal method. The dissolution and removal of lignin or most of the hemicellulose by various pretreatment methods is beneficial to improve cellulase accessibility. At present, a large number of studies have shown that lignin can significantly inhibit the enzymatic hydrolysis of cellulose, pretreatment can reduce lignin content and improve the efficiency of cellulose hydrolysis. In recent years, studies have shown that the relative content of Klason lignin would increase after the pretreatment of lignocellulose under severe conditions by using dilute acid and high temperature water. During the pretreatment processes of lignocellulosic biomass, lignin droplets may be deposited on the surface of the cellulose in the form of pseudo-lignin, so that it can inhibit cellulase hydrolysis more than natural lignin. However, no relevant review paper was found in the published articles. In this paper, the formation processes of lignin droplets and pseudo-lignin during the pretreatment of biomass were described. The possible mechanisms of pseudo-lignin production were put forward, and its composition and properties were reviewed. On this basis, the effects of lignin droplets and pseudo-lignin on the enzymatic hydrolysis of lignocellulose were summarized. Finally, the effects of lignin droplet and pseudo-lignin on the enzymatic hydrolysis of cellulose were discussed, and then the regulation strategy of pseudo-lignin formation was summarized. The authors believe that it is of great significance to study the mechanisms, structure characteristics, regulation mechanisms of the production of pseudo-lignin in the process of biorefinery. The formation of pseudo-lignin is a heterogeneous reaction process. At the same time, the formation mechanisms of pseudo-lignin can be studied from the mesoscale behavior due to the influence of mass transfer(molecular level)and the flow(macroscopic statistical level), and at the same time, the related models and theories should be established to realize their scientific quantitative descriptions and regulation. Moreover, it is beneficial to the development of lignocellulosic biomass refining processes and also it is conducive to promote the formation and development of an interdisciplinary scale of science.

Objective: The study is intended to reveal the threshold effect of household forestland transfer. It is important to identify the threshold characteristics and the non-linear effects of key factors in different threshold ranges for supporting decision-making for improving forestland transfer policy. Method: Based on the monitoring data of collective forest tenure reform of the State Forestry Administration in 2016 and survey data of farmers in Guangdong and Guizhou provinces in 2017, the panel data on the size of transferred household forestland was constructed for different forest blocks. From the perspective of power matching, the threshold variable is the size of household forestland management, and the core explanatory variable is the level of family income, the number of household labor force and whether they have forest certificate or not. Using threshold regression model, empirical tests of the threshold effect of the size of household forestland transfer and the non-linear influence of various factors were conducted. Result: Firstly, when the household income level and the number of household farming labors are taken as the core explanatory variables, the threshold estimates show that there are double thresholds for the size of household forestland management, with the values of 18 hm² and 20 hm², respectively. When the core explanatory variable is whether or not the forest ownership certificate exists, there exists a single threshold for the size of household forestland management, with a value of 33.4 hm². Secondly, When the size of household forestland management is more than 18 hm², the level of family income has a significant positive impact on the size of forestland transfer. When the size of forestland management is larger than 20 hm², its influence coefficient is obviously larger. When the size of household forestland management is less than 18 hm², the number of household farming labor has a significant negative impact on the size of forestland transfer. However, when the size of forestland management is more than 18 hm² and less than 20 hm², it has a significant positive impact. When the size of household forestland management is less than or greater than 33.4 hm², whether the ownership certificate has a negative and positive impact on the size of transferred forestland, but not significant. Samples were grouped according to the threshold value of household forestland management and then regression analyses were conducted to test the robustness of the estimated results, the significance of the influence of each core explanatory variable is different from that of the threshold estimation, but the direction is the same. Conclusion: Household forestland transfer is not unidirectional or linear, and the role of key factors has a threshold effect. Only at a certain level of forestland management, the increase of household income significantly promotes the size of forestland transfer. It shows that reducing the dependence of farmers on forestland may not be able to promote the transter of forestland. Within the threshold range for different sizes of forestland management, the impact of household farming labor force on the size of household forestland transfer is different. Transfer of rural labor force may not be able to promote the transfer of forestland. The effect of certification of forestland ownership on the size of household forestland transfer is also bidirectional and not significant, implying that the stabilization of forestland property rights is less important than policy expectation in promoting forestland transfer. Improving the policy on forestland transfer needs to pay attention to the threshold effect of household behavior. Relaxation of restrictions may not promote the transfer of rural forestland and may even have the opposite effect. Institutional supply can take into account the different demands of forestland transfer under different conditions. Increasing the flexibility and priority of policy implementation improves the institutional performance and promotes large-scale management of forestland.

Objective: Three national forest parks(Taibaishan, Taiping, and Wangshunshan from the west to the east in Shaanxi Province)were taken as a case to evaluate the current status of tourist satisfaction of the national forest parks, and to identify the key factors that affect the satisfaction, in order to provide evidences for developing strategies improve the tourist satisfaction. Method: Based on effective improvement, the tourist satisfaction levels were classified by the fuzzy comprehensive evaluation method in combination with the IPA analysis to find the advantage and disadvantage resources that affect the development level of the forest parks. Result: The results showed that the comprehensive satisfaction score of the three forest parks was 5.076, classified as"a little satisfied". The highest level of tourist satisfaction was on natural environment, classified as "very satisfied", and the lowest level was on tourism facilities and their quality and tourism information and communication, at classified as "dissatisfied". tourism consumption price was classified as "general satisfaction", and quality and safety of services, transportation and environment protection facilities and advertisements for attracting tourists were all classifiedas "a little satisfied". The IPA analysis showed that, 12 items were classified as "high importance-low satisfaction" and need urgent improvement, and they are ticket price, traffic price within the park, restaurant price, catering facilities, catering quality accommodation facilities, accessibility from external transport, mobile communication, WiFi access, diversity of rare animals and plants, values of cultural heritages and emergency facilities. Conclusion: In future development of forest parks, items with low satisfaction such as tourism facilities and their quality, tourism information and communication and tourism consumption price should be given priority for improvement. Specifically, we should create more tourist attractions, control the prices of catering and transport within the parks, meanwhile, it is vital to upgrade the facilities for catering and communication and improve the quality of catering and accommodation.

Objective: This study aims to find the optimal compost mixtures for mulberry growth. The effects of different ratios of compost mixtures of municipal sludge and garden waste and their application amount on mulberry growth were investigated, in order to provide the scientific basis for the circulation of garden waste and municipal sludge. Method: A poting experiment was conducted with a design of four different compost products and different dosages. Municipal sludge and garden waste were mixed at four volume ratios (0:1, 1:3, 1:1, 1:0, marking as W01, W13, W11, W10), and each compost was put together with soil at different volume ratios (0:1, 1:3, 1:1, 1:3, 1:0, marking as CK, T1, T2, T3, T4). The germination, plant height in different growth periods and biomass were measured in the poting experiment. Result: The germination of mulberry seeds were inhibited by all four compost mixtures.The germination was most strongly inhibited by W10 ratio under the same fertilization, and the germination was most strongly inhibited by T4 in all of the four different compost mixtures. The growth of mulberry seedlings was inhibited to various degrees with the increase of fertilizer application at the early growth stage (30-60 d), and the inhibition was weakened at the subsequent growth phase, and even the growth promotion happened by some treatments.The maximum plant height appeared in T2 treatment with W11 ratio. The biomass accumulations of aboveground and underground were increased to various degrees by all the treatments except T4 of W10. Conclusion: Mixed compost products containing sludge can inhibit the germination and the early growth of mulberry seedlings, however the growth and biomass accumulation of mulberry seedlings can be promoted with the development of time, among which the best effect is to apply 25% mixed compost with 1:1 ratio of sludge and garden waste.

Objective: To provide theoretical guidance for construction of Ulmus pumila shelterbelt, the adaptive mechanisms of C, N, P allocation of U. pumila seedlings in response to nitrogen deposition and increasing precipitation were studied. Method: A full factorial experimental design of two factors (nitrogen and water), was applied, i.e., four N fertilization levels (0, 5, 10 and 15 g N·m^-2a^-1) and three water treatments (natural precipitation, natural precipitation increased by 50% and 100%) with randomized block design. The C, N, and P contents in leaf, branch, stem, coarse root and fine root of U. pumila seedlings under the different water and nitrogen treatments were measured and their ratios were calculated, and the stability of C, N, and P and their relationships with allometric growth were explored. Result: There were significant interactions between nitrogen addition and increasing precipitation on N content, P content and their ratios in different organs of U. pumila seedlings. With the increase of N addition, C content increased in leaf and fine root, while it was unchanged in branch, stem and coarse root. Meanwhile, N content and N:P ratio increased in all organs, whereas C:N ratio decreased. P content declined in leaf and stem while C:P ratio elevated in leaf, stem and fine root. With the increasing of precipitation, C content reduced in leaf and fine root, while it remained unchanged in branch, stem and coarse root, and P content decreased and C:P and N:P ratios increased in branch and stem. The effects of precipitation increase on the element allocation were various under different nitrogen deposition levels. With the increasing of precipitation, under no N addition condition, N content and N:P ratio in leaf increased whereas C:N ratio decreased, and P content firstly increased and then decreased in leaf, coarse root and fine root whereas C:P firstly reduced and then elevated. Meanwhile, N:P ratio firstly increased and then declined in fine root. However, under 15 g N·m^-2a^-1 nitrogen addition condition, N content decreased, C:N ratio increased and N:P ratio remained unchanged in leaf, while P content declined and C:P ratio enhanced in leaf, coarse root and fine root, N:P ratio gradually elevated in fine root with the increasing of precipitation. C content of different organs followed the following order:stem > coarse root > leaf and fine root, while N and P content followed the order:leaf > fine root > branch, stem, and coarse root. Meanwhile, the coefficient of variation for C content followed the order:branch, stem, and coarse root < leaf and fine root. The variation coefficient of N content was the largest in leaf and coarse root, and the smallest in fine root. The variation coefficient of P content was the largest in stem and the smallest in leaf. The variation coefficient for C:N ratio followed the order:coarse root > leaf, branch, and stem > fine root, whereas the variation coefficients for C:P and N:P ratios followed the order:stem > coarse root > fine root > leaf and branch. The variation coefficient for N:P ratio was greater than those for N and P content. There were significant allometric growth relationships with C and N content in leaf, branch, coarse root and fine root of U. pumila seedlings. C content was negatively related to P content in leaf and coarse root. Furthermore, N content was negatively related to P content in each organ, and the index of allometric growth ranged from -0.534 to -1.224. Conclusion: With the increasing nitrogen deposition and precipitation, N limitation for the growth of U. pumila seedlings changed into N and P joint limitation. Meanwhile, N use efficiency decreased, but P use efficiency enhanced. The stability of N content was the strongest in fine root, while P content and N:P ratio stability were the strongest in leaf. The stability of N and P content were stronger than that of N:P ratio in each organ.

Objective: The PIN1 gene plays a role in the growth and development of plant roots by regulating the polar transport of auxin. In this study, the full-length cloning and functional analysis of the PmPIN1 gene of Pinus massoniana was carried out in order to reveal the molecular mechanism of rooting for cutting propagation of P. massoniana. Method: The cDNA sequence of PmPIN1 gene of P. massoniana was successfully cloned by PCR and RACE. Bioinformatics software was used to analyze the nucleic acid sequence, amino acid sequence and construct a phylogenetic tree of PmPIN1 gene. The expression of PmPIN1 gene in young roots, annual branch, young leaf and flowers of 10-year-old P. massoniana was analyzed by real-time polymerase chain reaction. The PmPIN1 gene was overexpressed in tobacco(Nicotiana tabacum)by Agrobacterium infection method to obtain transgenic plants, and the phenotypic differences between transgenic plants and pCAMBIA-1302 blank vector were compared, and PmPIN1-GFP fluorescent protein was observed in transgenic tobacco roots by laser scanning confocal microscope. The expression of auxin in roots, rhizomes and leaves of transgenic tobacco and wild tobacco was determined by enzyme-linked immunosorbent assay (ELISA). Treatment of wild-type and transgenic tobacco with different concentrations of auxin polar transport inhibitor (1-N-naphthylphthalamic acid, NPA), the changes of auxin content in tobacco roots, rhizome junctions and leaves were analyzed. 16318-hGFP-PmPIN1 recombinant vector was transferred to Arabidopsis thaliana protoplasts by PEG-mediated method for subcellular localization analysis. Result: The PmPIN1 gene is 2 914 bp in length and contains a 2 085 bp ORF, which encodes a protein consisting of 695 amino acids, with a membrane transport protein at the N-terminus and C-terminus. The phylogenetic tree showed that P. massoniana and P. tabulaeformis are on the same branch of the development tree. The difference in expression of PmPIN1 in different tissues was found to be extremely significant by real-time polymerase chain reaction, high expression in annual branch and young roots, lowest in flowers; Transgenic tobacco obtained by Agrobacterium rhizogenes-mediated transformation had higher growth, increased rooting and longer root length compared with a blank vector. Laser confocal microscopy showed that there was obvious green fluorescence enrichment around the root of transgenic tobacco. ELISA was used to determine the content of auxin in the roots and rhizomes of transgenic tobacco, and the content was found higher than that in wild type, and less in leaves than in roots and rhizomes. After treatment with different concentrations of NPA, the auxin content of wild type tobacco roots changed extremely significantly, and the auxin content decreased with the increase of NPA treatment concentration. When the treatment concentration was 10 nmol·L^-1, the auxin content in leaves was the largest. When the concentration was 2 nmol·L^-1, the content of auxin in the rhizome junction increased more. After treatment with different concentrations of NPA, the changes of auxin content in different parts of transgenic tobacco did not reach extremely significant. Subcellular localization analysis indicated that PmPIN1 protein was mainly distributed on the cell membrane. Conclusion: PmPIN1 of P. massoniana and PIN1 of P. tabulaeformis had a higher affinity. PmPIN1 belongs to membrane protein. PmPIN1 transgenic tobacco increases the transport capacity of auxin from aboveground to underground. Transgenic tobacco reduces the effect of NPA on auxin content, indicating that PmPIN1 likely regulates the polar transport of auxin. PmPIN1-GFP green fluorescence was enriched in the middle of the root, PmPIN1 was highly expressed in young roots. Transgenic tobacco had more roots and longer roots than transgenic plasmid. The above findings suggest that the PmPIN1 gene plays an important role in root development.

Objective: Liquidambar styraciflua, north American sweetgum tree is a new important exotic ornamental foliage tree that is widely used in urban areas of eastern China. To provide information for prevention and control of a new bark beetle pest, Acanthotomicus suncei, which damages north American sweetgum, we described morphological characteristics of the bark beetle and its biological characteristics as well as its occurrence status in Shanghai and adjacent regions. Method: We collected information of its biology and occurrence through field investigation. The proventricule and male genitalia of the beetle specimens were collected from host trees in the field. A stereo microscope was used to observe the morphological characteristics. The difference in the morphological characteristics from all known Acanthotomicus species in China were compared. Result: A. suncei has distinct identification characteristics. The placement of four elytral declivital spines arise on interstriae 2, 4, 6, and 8. Lateral tibiae of both foreleg and midleg have 4 dentations respectively, and the declivital spines of females are smaller than males. The differences in morphological characteristics from the three known Acanthotomicus species in China were significant. The length of A. perexiguus is less than 2 mm, with 3 pairs of declivital spines. A. spinosus carries 8 pairs of declivital spines while the length is similar with A. suncei. The beetle has 2 to 3 generations per year in Shanghai. The larvae feed on cambium and phloem in the trunk, causing rapid death of the host trees. It was found that 14 planting sites of American sweetgum were infested by A. suncei and more than 30 000 trees died from the beetle feeding under nurseries, parks or landscapes in Shanghai and adjacent regions. Meanwhile, L. formosana trees in some regions were also found to die after being attacked by A. suncei. Conclusion: The phenomenon of A. suncei attacking healthy sweetgum trees is reported for the first within the genus Acanthotomicus. A. suncei is an oligophagous insect, and the host range is limited to the genus Liquidambar. It's unlikely to harm other host plants. A. suncei prefers to American sweetgum, which may be related to the principle of physiological equivalence of the host plant. A. suncei is a serious threat to the introduction and cultivation of north America sweetgum. We recommend that monitoring should be carried out as soon as possible in planting areas of north American sweetgum trees. Once the infestation of A. suncei is found, the infested plants should be removed immediately, and isolation zones should be set up to protect healthy plants, which could prevent the spread of the pest. At the same time, it is necessary to strengthen the research on risk prediction, early warning, prevention and control method in the suitable distribution area of this pest, so as to lay the foundation for the final control of the pest.