Objective: The relationship between the three biomass estimation coefficients and the stand structure, climatic factors, and topographic factors was analyzed, and the main influencing factors of biomass estimation coefficients were determined to provide a scientific basis for accurately estimating the biomass of Eucalyptus plantations at regional scale. Method: By collecting and collating historical data from published literature on biomass measurements of Eucalyptus plantations, we analyzed and explored the relationship between three common biomass estimation coefficients (biomass conversion and expansion factor BCEF, biomass expansion factor BEF, and root/shoot ratio R) and stand structure (stand age, mean DBH, mean tree height, stand density, and standing volume), climatic factors (annual average temperature and annual average precipitation), and topographic factor (elevation). Result: Means of BCEF, BEF, and R were 0.658 Mg·m^-3 (n=119, SD=0.150), 1.251 (n=176, SD=0.167), and 0.190 (n=144, SD=0.102), respectively. The corresponding range values were 0.46-0.76 Mg·m^-3, 1.05-1.35, and 0.04-0.36, respectively. BCEF value displayed a decrease followed by an increase with the increase of mean DBH. BCEF value gradually decreased with the increase of mean tree height (r²=0.366), stand density (r²=0.430), and standing volume (r²=0.405). BEF value decreased and became stable with the increase of stand age(r²=0.765), mean tree height(r²=0.734), and standing volume(r²=0.578), decreased first and then increased with the increase of mean DBH(r²=0.644). R value decreased gradually and then became stable with the increase of stand age(r²=0.665), mean tree height(r²=0.338), stand density(r²=0.275), and standing volume(r²=0.403).BCEF value showed a decrease first followed by an increase with the increases of temperature (r²=0.193) and precipitation (r²=0.200). Values of BEF and R did not show a significant functional relationship with changes in temperature and precipitation. Three biomass estimation coefficients showed a trend of increase with elevation, and the equation fitting accuracies were 0.455, 0.501, and 0.314. Conclusion: The goodness of fit between stand density and BCEF was relatively high, and so did the stand age and the BEF and R. Stand density and age were the main factors affecting the estimation coefficient of biomass. The influence of topographic factors on the three biomass estimation coefficients was next only to the stand density and the age. The climatic factor only had some effects on the BCEF. Therefore, the difference in biomass estimation coefficients caused by stand structure and topographic factors should be considered when estimating the biomass of Eucalyptus plantations at regional scale.

Objective: A three-year (2015-2017) nitrogen and water addition control experiment was conducted in the southwestern margin of the Mu Us sandy land to investigate the effects and action pathways of increased nitrogen and moisture on the two dominant plant species (Artemisia ordosica and Leymus secalinus).This study was aimed to provide theoretical basis and case support for predicting nutrient cycling in desert ecosystems and nutrient limiting conditions for plant growth under future global environmental changes. Methods: For three successive years (2015-2017), a field control experiments with 2 factors and 9 interactive treatments were conducted in Ningxia Yanchi, Southwestern edge of Mu Us sandy land. Three nitrogen addition levels were N0(0 kg·hm^-2a^-1), N10(10 kg·hm^-2a^-1), and N60(60 kg·hm^-2a^-1). Three water addition levels were W0(natural precipitation), W20(20% increase over natural precipitation), and W40(40% increase over natural precipitation). We performed two-way ANOVAs to examine the responses of soil moisture, soil inorganic nitrogen and soil available phosphorus, soil Ca²⁺ content, and the leaf N:P of A. ordosica and L. secalinus to nitrogen and water addition. Then we used structural equation modeling to test their relationships. Results: Nitrogen addition significantly increased soil inorganic nitrogen and the leaf N:P of A. ordosica and L. secalinus, while no significant effects on soil available phosphorus and soil Ca²⁺ content were detected. Water addition decreased the leaf N:P of L. secalinus and soil Ca²⁺ content, but had no significant effect on soil inorganic nitrogen, soil available phosphorus, and the leaf N:P of A. ordosica. Conclusion: Nitrogen addition relieved the N limitation, but exacerbated P limitation. Water addition reduced the leaf N:P by changing soil (0-20 cm) Ca²⁺ content, therefore P limitation has been alleviated to some extents.

Objective: The aims of this study were to investigate the change trends of carbon storage and its distribution pattern(vegetation, litter and soil layer) within forest ecosystems at different restoration stages in hilly area of central Hunan Province of China, in order to provide a scientific basis for explaining the influence mechanism of vegetation restoration on carbon sink function of forest ecosystem, and implementing forest ecosystem carbon reservoir management measures in stages. Methods: By using the space-for-time substitution method, we selected four different types of ecosystems, comprising of Loropetalum chinense+Vaccinium bracteatum+Rhododendron simsii scrub-grass-land (LVR), L. chinense+Cunninghamia lanceolata+Quercus fabri shrubbery (LCQ), Pinus massoniana+Lithocarpus glaber+L.chinense coniferous-broad leaved mixed forest (PLL), and L. glaber+Cleyera japonica+Cyclobalanopsis glauca evergreen broad-leaved forest (LAG) to represent the successional sequence in the secondary forests in Changsha County, Hunan Province, China. Permanent plots were established in each ecosystems.Biomass was estimated by using the total harvesting method to establish relative growth equations of some dominant tree species and citing allometric equations of biomass of some dominant tree species. Soil samples (0-40 cm) were collected and divided into four layers (0-10, 10-20, 20-30, and 30-40 cm). Carbon contents in plant, litter, and soil samples were determinated, and carbon storage of vegetation, litter, and soil were estimated. Results: Carbon contents of different components at different vegetation layers varied with vegetation restoration. In the same restoration stage, carbon contents of different components at different vegetation layers ranked in the order of the arbor layer > the shrub layer > the herb layer. Carbon contents of litter were highest in PLL, followed by LAG and LCQ as the lowest. Soil organic carbon contents increased with the vegetation restoration.From LVR to LAG, carbon storage of vegetation, litter, 0-40 cm soil and ecosystem increased by 70.80, 1.17, 67.05 and 139.02 tC·hm^-2, respectively. The growth rate of carbon reserves in vegetation layer and ecosystem between different stage showed the characteristics of first fast and then slow. However the growth rate of carbon reserves in soil showed fast-slow-fast. Carbon stock within ecosystem showed a consistant spatial distribution pattern:0-40 cm soil layer > vegetation layer > litter layer in different restoration stages. With vegetation restoration, the contribution rate of carbon stock in vegetation layer to the ecosystem carbon stock increased, while that of soil carbon stock was in the decline, and that of litter carbon stock did not change. Carbon storages of ecosystem, vegetation, and soil were significantly positively correlated with species diversity index (except for vegetation), biomass in vegetaion, and soil organic carbon content. Conclusion: With vegetation restoration, plant diversity, vegetation biomass, soil organic carbon content, carbon storages of ecosystem and its each components (vegetation, litter and soil) increased. However the growth rates of carbon reserves in vegetation, soil and ecosystem showed different among different restoration stages. Therefore, it is an important way to improve the carbon reserve of subtropical forest ecosystem to promote forest vegetation restoration and improve tree species diversity, vegetation biomass, and soil organic carbon content in order to improve carbon reserves of the vegetation and soil by reasonable management measures in the early and middle of restoration stages, and to protect the above-ground vegetation and ensure the continuous increase of soil organic carbon content in the late stage of vegetation restoration.

Objective: In this study, the effects of paclobutrazol (PP₃₃₃) and chlormequat (CCC) on the growth of chestnut young branches and leaves, and carbon-nitrogen metabolism of leaves were investigated, which aims to provide a scientific basis for comprehensive understanding of the effects of plant growth retardants on the growth of chestnut saplings and their application. Methods: The 6-year-old Chinese chestnut variety Castanea mollissima 'Yanshanzaofeng' was selected as the test material. Two kinds of retardants, paclobutrazol and chlormequat, were sprayed on the leaves during the rapid growth period of branches. The retardant concentrations were set as 100, 200 and 300 mg·L^-1, with water served as the control (CK). After treatment, the growth index of mother branch, fruit branch, vegetative branch, single leaf area, leaf length-width ratio, leaf water content, relative chlorophyll, carbon and nitrogen metabolite content were regularly measured, and those collected data were used to explore the effect and application feasibility of the two kinds of retardants. Results: The main results were as follows:1) Paclobutrazol and chlormequat significantly inhibited the longitudinal growth of mother branch, fruit branch and vegetative branch of young chestnut trees, and promoted the basal diameter, and there were significant (P < 0.05) differences of all treatments compared with the control. For fruit branches, the effect of spraying 200 mg·L^-1 chlormequat was the most significant on length growth, and the growth was about 81% less than the control. The growth of base diameter of fruit branch was significantly increased by spraying 100 mg·L^-1 chlormequat, and the growth was about 74% higher than the control. 2) Paclobutrazol and chlormequat significantly reduced the single leaf area and increase the ratio of leaf length to width, leaf water content and relative chlorophyll content. Among treatments, spraying 200 mg·L^-1 chlormequat reduced the single leaf area by 11% compared with the control, and increased the relative chlorophyll content by 10.28% compared with the control. Spraying 300 mg·L^-1 paclobutrazol significantly increased the content of leaf water, with 28% higher than the control. 3) Paclobutrazol and chlormequat were able to significantly promote the accumulation of carbon and nitrogen metabolites of young chestnut leaves. Compared with the control, spraying 300 mg·L^-1 paclobutrazol or 100-200 mg·L^-1 chlormequat significantly increased the content of soluble sugar, total nitrogen and the ratio of carbon to nitrogen. Conclusion: Based on the comprehensive analysis of the effects of two kinds of retardants on branch growth and leaf physiological indexes, it is found that spraying 100-200 mg·L^-1 chlormequat during the rapid growth period of young trees can significantly promote the diameter of mother branch and fruit branch, and inhibit their elongation growth, and also effectively promote the accumulation of carbon and nitrogen metabolites in leaves.

Objective: Castanopsis hystrix is a rare broadleaved tree species under the second grade national protection in China, and it is difficult to regenerate in nature. Our study aims to examine whether population regeneraion is limited by seedling recruitment. We investigated dynamics of seed rain, soil seed bank and seedling regeneration of C. hystrix. Methods: The line transect method was used to collect the seed rain and fallen leaves of C. hystrix in 2017 and 2018. Seed rain density, quality, total of seed rain and weight of fallen leaves in different seed dispersal stages were analyzed. At the same time, small plots were also set under the seed trees for collecting samples in litter layer, 0-5 cm humus layer and 5-10 cm soil layer. The soil seed bank density and the number of full seeds were calculated then, and the germination capacity and the weight of thousand seeds were measured in laboratory. In May 2018, small plots were set around each of sampling seed trees to investigate the seedlings regeneration. Results: 1) Seed rain of C. hystrix lasted from the middle of September to the late of December, and its concentrated scatter period was from October to November. In 2017, it was a big year for producing seeds of C. hystrix, and the seed rain density was (480.97±11.61) seeds The seed quality was good, the number of full seeds was (433.86 ±12.65) seeds·m^-2, accounting for 90.20%±1.09% of the total seed rain. In 2018, it was a small year for seed production, both seed production and full seeds proportion were lower than those in 2017. The seed rain density was (126.37±12.04) seeds·m^-2, and the full seeds accounted for 36.04%±0.95% of the total seed rain. 2) The soil seed bank in April 2018 was mainly from the seed rain in 2017, and the average density of soil seed bank was (360.09±10.43) seeds·m^-2, of which full seeds accounted for 59.74%±8.56%. By indoor germination test in 2018, the average germination rate of full seeds was 28.53%±7.50% in seed bank. There were about (61.38±18.57) seeds·m^-2 having germination potential before natural regeneration. However, when the seeds were buried into the forest soil till April in 2019, the germination rate decreased to 2.85%±0.86%, and only about (8.59±1.90) seeds·m^-2 had germination capacity in seed bank. Approximate 63.79%±3.55% of seeds in the bank were mainly distributed in litter layer. 3) The average renewal frequency of seedlings of C. hystrix was 16%, and only 11 of the 78 regenerated seedlings were survived. Conclusion: The dynamics of seed rain diffusion is consistent with that of fallen leaves of C. hystrix. The vertical spatial distribution of soil seed bank is significantly different, and the most of the seeds fall into litter layer. The germination rate and survival rate of seedlings are low, it is still difficult for seedling recruitment even if after a big year of C. hystrix. Thus, low seed germination rate and litter barrier are the main influencing factors leading to the poor regeneration of C. hystrix.

Objective: Plant embolism vulnerability is a hot issue in hydraulics studies of woody plants, and is generally assessed by establishing vulnerability curve (VC). Centrifuge method is one of the main method being applied to establish the VC. Previous studies have generally believed that when the Cavitron centrifuge method was used to establish the VC of a long-vesselled tree species, the vessels inside the centrifuged branch was cut open, and the presence of a large number of open vessels causing the embolism artifact, resulting in extremely vulnerable "r-shaped" curve, so significantly overestimated the cavitation vulnerability of plants. This study was intended to test whether the type of VC is affected by the proportion of open vessels at the inter-specific level, and to lay a foundation for the reliability of centrifuge method in assessing the plant embolism vulnerability, therefore, the plant's cavitation resistance can be more accurately evaluated, which provides a reliable basis for the selection of drought-resistant tree species in ecological construction. Methods: Nine tree species with different vessel lengths were selected. According to the Cavitron centrifuge rotor diameter (27.4 cm), nine tree species were divided into three categories:long-vesselled species (average vessel length > 15 cm, Robinia pseudoacacia, Morus alba and Lagerstroemia indica), medium-vesselled species (average vessel length 10-15 cm, Ligustrum lucidum, Amygdalus persica, Hippophae rhamnoides) and short-vesselled species (average vessel length < 10 cm, Acer truncatum, Corylus heterophylla, Populus alba 'I-101'×(P. alba×P. glandulosa '84K'). The VCs were established by Cavitron centrifuge. Maximum and mean lengths of vessels were measured by air injection technique. Relationships between open vessels fractions and characteristics of the VCs were analyzed. Results: The VCs of long-vesselled species and short-vesselled species of A. truncatum and C. heterophylla could be well fitted by single Weibull function, while the VCs of medium-vesselled species and short-vesselled species of I-101×84K could be well fitted by double Weibull function. The VCs of long-vesselled R. pseudoacacia and M. alba were similar, showing "r-shaped", while that of L. indica was "s-shaped"; the VCs of medium-vesselled H. rhamnoides and L. lucidum, and short-vesselled I-101×84K were double Weibull shape consist of two "s-shaped" curves, while the VC of medium-vesselled A. persica was closer to "s-shaped"; the VCs of short-vesselled A. truncatum and C. heterophylla were both "s-shaped". The mean vessel lengths (L_v) of long-vesselled species were close to 20 cm, the proportion of vessels with both ends opened (F_27.4) was about 20%, the proportion of vessels opened from one end to the center of centrifuge rotor (F_13.7) was about 60%; the L_v of medium-vesselled species was close to the radius of centrifuge rotor (13.7 cm), F_27.4 was about 10%, and F_13.7 was about 40%; the L_v of short-vesselled species was below 5 cm, F_27.4 was less than 0.1%, and the maximum value of F_13.7 was 2.68%. The embolism vulnerability indices P₁₂ and P₅₀(xylem water potentials correspond to hydraulic loss of 12% and 50%, respectively) of nine species were positively correlated with the proportion of open vessels (F_27.4 and F_13.7), but P₈₈(xylem water potential corresponds to hydraulic loss of 88%) was not significantly correlated with the proportion of open vessels. Conclusion: At the inter-specific level, this study verified that the proportion of open vessels significantly affected the types of embolism vulnerability curves established by Cavitron centrifuge. When the proportion of open vessels was very few, the VCs were "s-shaped", but with the increase of the proportion of open vessels, the "r-shaped" and "intermediate-shaped" curve may be formed. This conclusion further supports the hypothesis of open vessel artifacts, and provides a theoretical basis for the selection of tree species when measuring the embolism vulnerability by Cavitron centrifuge.

Objective: Ostrya multinervis is a species endemic to China, and it is listed as a rare and endangered wild plant, and a species with extremely small population in Zhejiang Province. The wild O. multinervis trees are found to be very rare in Zhejiang Province with very few young-aged plants and a declining population. During the evolution process, the chloroplast genomes are relatively conserved and thus provide useful information for genetic relationship analysis and phylogenetic studies. In the present study, based on the assembly of chloroplast genome, sequence characteristics were determined to confirm its structure and gene organization. By phylogenetic analysis, relationships and taxonomic ranks with its relative were identified. Methods: Genomic DNA of O. multinervis was extracted by using CTAB method, and a library was constructed for high-throughput sequencing with HiSeq X Ten with the paired-end strategy. The chloroplast genome was assembled by using NovoPlasty, and PCR was applied to isolate the border sequences following sequencing verification. SSR loci were detected by MISA and a phylogenetic tree was generated using PhyML 3.0. Results: A total of 19 869 412 clean reads were obtained by getting rid of both adaptors and low quality sequences. The result indicated that the complete O. multinervis chloroplast genome was 159 583 bp in length containing a typical quadripartite structure, and the lengths of large single copy, small single copy, and inverted repeat were 88 514 bp, 18 953 bp, and 26 058 bp, respectively. The O. multinervis chloroplast genome contains 131 genes, with 87 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. Among them, ycf1 and ycf15 were pseudogenes, and their sequences were shorter than normal ones. A total of 58 SSR loci were predicted from O. multinervis plastome, and 53 of which were mononucleotide repeats. Multiple sequence comparison showed the highest similarity between O. multinervis and O. rehderiana (99.1%) and the lowest was between O. multinervis and O. japonica (98.7%). The best fit model for constructing a phylogenetic tree was GTR+G+I, and the Akaike information criterion and Bayesian information criterion were 556 643.629 64 and 556 954.642 07, respectively. The phylogenetic analysis indicated that 12 plants could be divided into two groups, and Alnus japonica and A. rubra from the tribe Betuleae were grouped into one clade, while 10 plants from tribe Coryleae were grouped into another clade. O. multinervis and the other three Ostrya species clustered in the same clade with 100% of bootstrap support. Conclusion: Based on the high-throughput sequencing, the chloroplast genome of O. multinervis was assembled, and its structure and gene organizations were confirmed. Higher similarities in chloroplast genome sequences were found between O. multinervis and other three Ostrya species, and they shared the same clade. The assembly, sequence comparison and phylogenetic analysis provide a basis for genetic structure and population diversity studies in the future.

Objective: Heat shock transcription factor (HSF) plays an important regulatory role in plant response to abiotic stress. The aim of this study was to identify the stress resistance function of BpHSFA4 in birch(Betula platyphylla) in order to lay a theoretical foundation for using the gene in tree breeding through genetic engineering. Methods: The BpHSFA4 cDNA sequence was obtained by searching with birch transcriptome libraries. Further, the BpHSFA4 gene was cloned by RT-PCR. And the BpHSFA4 cDNA sequence was analyzed using bioinformatics tools. Quantitative real-time RT-PCR was used to monitor the expression patterns of BpHSFA4 genes in the leaves, stems and roots of birch under different stress treatments. The vector of overexpression pROKⅡ-BpHSFA4 and silencing expression vector of pFGC5941-BpHSFA4 were constructed and transient transformed into birch. The empty pROKⅡ was also transient infected into birch as a control. The MDA content, H₂O₂, SOD activity, POD activity, electrolyte leakage and diaminobenzidine(DAB), nitrotetrazolium blue chloride (NBT) and Evans blue staining under NaCl stress were measured and compared between transgenic (OE, SE) and control (CK) plants. Results: The results showed that the cDNA length of BpHSFA4 was 1 170 bp. The protein encoded by this BpHSFA4 gene was 389 amino acids. The relative molecular weight of BpHSFA4 protein was 44.15 kDa, with isoelectric point 5.14. The typical HSF domain was found in the BpHSFA4 sequence.The results of qRT-PCR showed that the expressions of BpHSFA4 gene were different under abiotic stresses and hormone treatments compared to the control. Furthermore, the expressions were significantly different at least at one stress point time for each treatment. In addition, the expression patterns of BpHSFA4 gene were more significantly changed under NaCl stress. To determine whether BpHSFA4 displayed a successful overexpression(OE) or a suppressed expression (SE), the transcript levels of BpHSFA4 in the three types of transformed birch plants were measured by qRT-PCR. The results showed that the expression of BpHSFA4 was significantly higher in OE plants and clearly lower in SE plants, especially 12 h after transformation, indicating that these transient expression plants were suitable for further study. Under NaCl stress, The NBT and DAB staining and H₂O₂ content also showed that overexpression of BpHSFA4 markedly reduced ${\rm{O}}_2^{\bar \cdot }$ and H₂O₂ accumulation, while suppressed expression of BpHSFA4 led to elevated accumulation of ${\rm{O}}_2^{\bar \cdot }$ and H₂O₂. The SOD and POD activities of transgenic birch plants showed that OE had the highest SOD and POD activities, and that SE plants had the lowest SOD and POD activities. The Evans blue staining and MDA content and electrolyte leakage showed that cell death greatly decreased in the OE plants, but greatly increased in the SE plants. Conclusion: BpHSFA4 gene can respond to abiotic stresses and hormone treatments, and stronger under salt stress, it indicates that the gene may be involved in the response to salt stress in birch trees. All results indicated that overexpression of BpHSFA4 improved the salt stress tolerance by increasing the ability to scavenge reactive oxygen species (ROS), the activities of SOD and POD to reduce the accumulation of H₂O₂ and ${\rm{O}}_2^{\bar \cdot }$, thereby reducing cell damage or cell death and enhancing birch resistance. BpHSFA4 was proved to be a candidate gene responding to stresses.

Objective: Considering the character of forest disturbance in China is frequent and complicated, we use the series trajectory analysis method to monitor forest disturbance which can provide references for carbon cycle and carbon accumulation of terrestrial forest ecosystems and climate change research. It is of important significance to the terrestrial carbon cycle and climate change research. Method: We conduct a study in Changting county base on 15 Landsat time-series data from 2000 to 2016 by adopting a time-series trajectory analysis technique(LandTrendr)to identify forest disturbance which apply segment properly and fit linearly a time sequence on the time-series trajectory. The results are verified based on field survey and pixel of interference by using the Google image and global 30 m resolution of GDEM digital elevation products. Result: The total area of forest disturbance is 192.49 km² and the mean area is 12.83 km² within the area from 2000 to 2016, of which that in 2001 is the minimum and less than l km².The most serious disturbance occurred in 2004, 2008 and 2009. The area all over 30 km² and occupy about 1.3% of forest area in those years. In the three years, the total area represent 50% of the forest disturbed area and the biggest disturbance area is 32.85 km² in 2004. In 2003, 2006, 2007 and 2010-2011, the disturbance area was slightly larger than 10 km², but less 0.6% of forest area in this year. It's much less than 10 km² for remaining years. The area of forest disturbance fluctuates greatly in individual years, but it is decreasing over time. The duration of forest disturbance is mainly about 1 to 3 years and the largest disturbance area occurred in 1 year which up to 82%. Disturbance is mainly concentrated in the east of Changting where is near the non-forest area. It's obvious that disturbance area is declined with the elevation and more than 60% of disturbance occurred at low-middle altitudes. Combined with visual interpretation of Google images, it is shown that the forest disturbance in Changting is mainly caused by forest fires and artificial deforestation, which mainly occurs in low altitude areas near the non-forest areas. Conclusion: The results of field survey and pixel of interference are consistent with the results of monitoring. Disturbance patch can be extract completely and the boundary is accurate and distinct, so is the fine disturbance. Base on pixel scale accuracy verification to monitor forest disturbance, it is showed that the overall accuracy reaches 96.26%, with a Kappa coefficient of 0.92. In all years, the accuracy of users is over 80%., and the accuracy of producers is more than 75% except several years. The results require a high monitoring accuracy, indicating a significant potential of the technique for forest disturbance monitoring.

Objective: Based on the accurate measuring of the stem volume of moso bamboo(Phyllostachys edulis), the research on bamboo stem volume models was conducted to accurately estimate the stem volume and to provide a theoretical basis for the management of bamboo forest. Method: Taking moso bamboo as the research object, based on the measured data of 216 samples of bamboo from Lin'an, Qingyuan, Wuyi, Changshan, Ninghai, Anji, Zhuji, Yuyao, Huangyan and Taishun county of Zhejiang Province, drainage method that could measure the volume of irregular shaped object was used to measure the bamboo stem volume. Firstly, based on the allometric equation and the equation proposed by Terasaki Watari, taking the diameter at breast height(D)and the internode length of bamboo at breast height(L)as the independent variables, one unary model(M₁)and four binary models(M₂-M₅)were selected to establish the three bamboo stem volume models with all the samples data. Secondly, model error structures were analyzed with the likelihood analysis with which whether the log-transformed linear models or nonlinear weighted models were chosen for model fitting. The parameter estimations were obtained by fitting regression of the models using ForStat2.2 software. Finally, the bamboo stem volume model that fit for Zhejiang Province well and had stable parameters and higher prediction accuracy was selected according to analysis towards the results of t test for the parameter estimates and 4 validation statistics, namely the adjusted coefficient of determination(R_a²), the standard error of the estimate(SEE), the mean errors(ME)and the mean systematic errors(MSE). Result: The Akaike's information criterion(AICc)of the 5 basic models were calculated with the likelihood analysis of model error structure. The results showed that the value of ΔAICc was larger than 2, which indicated the multiplicative error and the use of log-transformed model for model fitting. The parameters of the 5 bamboo stem volume log-models established were stable for the absolute t-value was larger than 2. All of the R_a² were above 0.95, and the SEE and MSE were around 0, respectively, which reflected the well-fitting, and the model M₂ fit the best. The statistics of model fitting and prediction across diameter classes were investigated as well. The results illustrated that the fitting and prediction performance across diameter classes of the 5 models was quite preferable, yet better when assuming the medium diameter classes and a bit worse as assuming the class of 4.0-5.9 cm and that of 14.0-15.9 cm. Finally, the prediction log-models with correction did not perform a better fitting effects and prediction precision. Conclusion: Drainage method is a better method for accurate measurement of bamboo stem volume. Likelihood analysis is suitable to analyze the error structure and provide with a reliable justification of choosing the fitting models. The evaluation accuracy of binary models is higher than that of unary model as the variable H and L are introduced. Considering the easier and more accurate measurement of internodes length of bamboo at breast height(L)in practice, and the stem volume model M₅ performs better than model M₂, the suggested suitable model for predicting the stem volume is M₅ that is based on variable D-L, i.e.V=0.191 2D^{2.114 9}e^{-6.841 1/L}.

Objective: In this study,endophytic bacteria were isolated and screened from a wild apple (Malus sieversii) in Xinjiang,which is an excellent germplasm resource in China,in order to obtain new bacterial resources for biological control of apple diseases. Method: Endophytic bacteria were isolated from the branches of M. sieversii by the methods of dilution plating and tissue isolation. Seven endophytic bacteria strains,with the strong inhibitory effect on three pathogenic fungi (Botryosphaeria dothidea,Colletotrichum gloeosporioides and Phomopsis mali),were selected by the method of plate confrontation. The 7 strains were identified based on morphological,physiological and biochemical characteristics,as well as 16S rDNA sequence analysis. Their pathogenicity was determined by using in vitro inoculation tests. Result: In this study,a total of 217 strains of endophytic bacteria were isolated and purified,among which seven strains (M-m7,M-m12,M-r12,P-m9,P-m11,L-m12 and P-r21) with strong inhibitory effects on mycelium growth of three pathogenic fungi of B. dothidea,C. gloeosporioides and P. mali were screened out. Their inhibition rates were 77.00%,72.60%,76.60%,60.64%,65.96%,65.81% and 71.79% on B. dothidea; 69.85%,64.95%,68.87%,68.37%,56.12%,53.54% and 65.66% on C. gloeosporioides; 77.63%,79.22%,72.60%,69.37%,70.27%,69.30% and 71.05% on P. mali,respectively. Strains M-m7,M-m12,P-m11 and L-m12 were identified as Bacillus subtilis,strains M-r12 and P-m9 were identified as B. elezensis and strain P-r21 was identified as B. amyloliquefaciens. Inoculation tests showed the 7 strains had no pathogenicity to apple tree itself. Conclusion: Seven strains of endophytic bacteria in M. sieversii can effectively suppress mycelium growth of B. dothidea,C. gloeosporioides and P. mali,and have no pathogenicity to apple tree.

In this paper, a new species, Zaraea mengmeng Yan, Li & Wei sp. nov. (Hymenoptera:Cimbicidae), collected from the Mt. Tianmu, Zhejiang Province, China, is described. Its larvae feeding on leaves of Padus brachypoda and could defoliate entire leaves of the host tree with high density, which will affect its growth, thus affecting the yield of fruit trees and seriously reducing the economic benefits of trees. The new species develops one generation a year in the Mountains and overwinters in the form of pre-pupa. This new species is very similar to Z. akebiae, but can be distinguished from the latter by the following characters:metanotum and abdominal tergum 1 entirely yellowish white; tibia and tarsus of each leg dark brown; the ventral half of mesepisternum smooth and sparsely punctured. The genomic DNA of the new species was extracted using the DNeasy Tissue Kit (Qiagen, Valencia, CA), 12 sequences of Cytochrome oxidase Ⅰ(COⅠ) (2 sequences of the new species and 10 sequences of other species of Cimbicidae were obtained from the mitochondrial gene, with a length of 850 bp; In addition, we downloaded 23 COⅠ sequences of known Cimbicidae and related genera species used in previous phylogenetic analyses from GenBank database, which constitute the CO Ⅰ sequence data set with the new species sequence (35 samples in total). The genetic distance of Abiinae was analyzed and the results showed that the genetic distance is 0.005 between two samples of the new species. Each of the clade Zaraea, Orientabia and Abia, are recovered as a monophyletic group, with high support for the BI trees (Posterior probability >0.96). We suggest that Zaraea, Orientabia and Abia are three valid genera of Abiinae. Results of molecular analysis of the new species are consistent with those of morphological identification, which supports the establishment of new species.

Objective: In order to provide theoretical basis for developing of bionic wood sound absorption material, the sound absorption structure of the bionic wood is designed according to the wood structure. Then, the hole angles of the absorption structure are tested. Method: First of all, we modeled the bionic wood sound absorption structure with Rhinoceros 3D software, and prepared this structure by 3D printing technology. The influences of different inclined angles(15°, 30°, 45°, 60°)on the resonant frequency and sound absorption coefficient were investigated by means of impedance tube transfer function. Then, the sound absorption properties of 3D printed perforated plates were compared. Result: 1) This study found that the 3D printed perforated plates had two resonance frequencies, which were at the low frequency and the middle high frequency, respectively. However, the sound absorption structure of 3D printed bionic wood had three resonant frequencies, which were located at low frequency, medium to high frequency and high frequency, and wood perforated plate only had low resonance frequency. 2) The angle of the perforation had effect on the sound absorption performance of the 3D printed perforated plate. At low frequency, the resonance frequency would move to the low frequency direction with the increase of the inclination angle. The peak of the sound absorption coefficient was above 0.8; in the medium to high frequency section, the angle changed with the angle of the complex hole. The resonance frequency and the peak absorption coefficient of 3D printed perforated panel were both changed, but there was no a clear law. However, the peak of sound absorption coefficient was about 0.3, and the sound absorption performance was poor. 3)The inclined angle of the hole had a great influence on the sound absorption property of the 3D printed bionic wood sound absorption structure, the sound absorption law of the low frequency section and the medium to high frequency section was basically the same as that of the 3D print perforated plate. In the high frequency section, the common vibration frequency moved to the low frequency direction with the increase of the hole angle. The peak value was above 0.8, and had a good absorption performance. Conclusion: The 3D printed bionic wood sound absorption structure with different hole angle presented good sound absorption properties at low frequency, medium to high frequency and high frequency, which were not found in the previous studies of perforated sound absorption materials. In addition, at high frequency, the resonance frequency of the 3D printed bionic wood sound absorption structure with different angle is larger, which lays a theoretical foundation for the design of the future full frequency sound absorption structure. This experiment provided a new research field for the new composite materials which can design the sound absorption frequency. It will have a good prospect in some special sound absorption environment.

Objective: China has been using the cross-spraying method of air and ground to control forest pests. Stereoscopic spraying chemical has been adopted in the forestry pests control which apply pesticide both on the ground and in the air. Due to greater human awareness of environmental conservation and public health, pests and diseases control requires accurate, efficient, scientific, and reasonable operation according to the actual conditions. A wide variety of choices and decisions must be made by applicators to result in a successful pesticide application. Examples of these choices include proper adjuvant mixture and spray equipment (e.g. nozzle type and orifice size) and application technique (e.g. spraying pressure) selection while also considering environmental influences such as wind speed. Droplet size is one of the most important factors affecting spray application, efficacy, drift and spray performance optimization. Method: A laser diffraction technique in wind tunnel was used to provide complimentary information on droplet size distribution and spectra. Droplet size was determined by application conditions (nozzle type, spraying pressure, operation condition and wind speed), and tank mixing physical properties were affected by the carriers (water or oil) and adjuvants (drift retardant, surfactant and wetting agent). These sprays were atomized using ground nozzles and aerial nozzles placed in a wind tunnel and the droplet spectra measured via a laser diffraction instrument. Result: Experimental results showed that the VMD decreased with the increase of the spray pressure and decrease of nozzle's orifice size. It was also showed by tests that when spraying 41A liquid as drift retardant, VMD produced by nozzles increased compared with water as solution in the wind tunnel, and all the nozzles' RS value increased, the spectrum category changed. When the CHEMWET100 as wetting agent and LI700 as surfactant, VMD produced by import nozzles and domestic nozzle reduced lightly and the spectrum category remained the same. Droplet size sprayed by CP nozzles could be changed both by orifice size and deflector angle. Increasing the deflector angle produced smaller droplets, e.g., 30° produced smaller droplets than those of 0°. Meanwhile, using a downward deflection of 30 degree might have improved relative RS of droplet sizes for CP nozzle. Conclusion: Spray mix composition and adjuvant could have a large effect on droplet size and spray performance criteria. During aerial application, in order to reduce the drift of airborne droplets, appropriate pesticide additives (such as drift retardant 41A) should be added to increase the droplet size and improve their adhesion. During ground application, appropriate pesticide additives (such as surfactant LI700) should be added to reduce the droplet size and enhance the deposition rate in order to ensure the coverage area and canopy penetration. For the leaves of trees with a thick waxy layer, the surface might be difficult to be wetted by the pesticide solution. When spraying pesticides on these targets, the wetting agent CHEMWET should be used to increase the wettability and adhesion of the pesticide solution to the target surface.

Objective: This study was carried out to explore the release characteristics of VOCs and odor from lacquer veneer particleboards,at the same time,analyze the influence of environmental factors on the components of VOCs and odor in the equilibrium state. Two kinds of lacquer Fraxinus mandshurica veneer particleboards were analyzed by gas chromatography-mass spectroscopy/olfactometry in this research. The emission of VOCs and odors from different lacquer veneer particleboards was compared,and the basic data were provided for further odor research. Method: This paper established a single factor experiment matched to the appropriate environmental conditions to analyze the release rule of VOC and odor from nitrocellulose lacquer veneered particleboards and water based acrylic lacquer veneered particleboards under different environmental factors. On the one hand,the characteristic odor compound and their resources from lacquer particleboards were indentified. On the other hand,the effects of environmental factors on the VOCs and the odor release of lacquer particleboards were investigated. Finally,the VOCs and odor release of the two lacquer veneer particleboards were evaluated by the method of "synthetic index-olfactory evaluation method ". Result: Compared with nitrocellulose lacquer veneered particleboard,water based acrylic lacquer veneered particleboard has a lower TVOC concentration,less odor amount and lower total odor intensity. Aromatics and esters exceeded the standard most seriously in both kinds of boards. The main components of odor emission released from nitrocellulose lacquer veneered particleboards were aromatic,esters,and alcohols,whereas,those of water based acrylic lacquer veneered particleboard's were aromatics and alcohols. For different odorous compounds,there was no direct correlation between odor intensity and its concentration,but,for the same odorant compound,its concentration affected the odor intensity somewhat. Furthermore,with the increase of ratio of air exchange rate to loading factor,the TVOC emission concentration and total value of odor intensity from two kinds of lacquer particleboards declined,but it increased with the temperature increase. At the same time,when relative humidity increased,the TVOC emission concentration and total value of odor intensity from nitrocellulose lacquer veneered particleboards increased,but the TVOC emission concentration and total value of odor intensity from water based acrylic lacquer veneered particleboards declined. The proportion of the odor substance concentration in the total VOCs concentration decreased with the increase of temperature and relative humidity. The ratio of air exchange rate to loading factor had a little effect. Conclusion: Gas chromatography-mass spectroscopy/olfactometry could be used as a method to detect the odor from wood-based panels and furniture materials. Compared with nitrocellulose lacquer veneered particleboard,water based acrylic lacquer veneered particleboard might be a more suitable material for interior decoration. The total odor intensity and odor grade of two kinds of painted veneer particleboard might be fitted by Gaussian function.

Objective: Small-diameter log is integrated by half-sectional finger joint process in order to improve its recovery. Methods: The mathematical model of the ideal log and log integrated by half-sectional figure joint was established, respectively. The slab was cut to process finger-joint when the central angle was set as 60°. Additionally, the volumes of log, slab and finger joint section were calculated to obtain the effective volume of small-diameter log. Logs with diameters of 120-190 mm were chosen. The long-diameter and short-diameter of 5 groups of small-diameter log were measured, and their recoveries were calculated. Results: The recovery of finger-joint log increased with an increasing diameter. When the diameter of log was 190 mm, according to the mathematical model of the ideal log, the volume of log was 32 022.51 mm³; according to the mathematical model of the slab, the removal volume was 966.46 mm³; according to the mathematical model of the finger joint, the removal volume was 3 907.93 mm³. According to the above data, the recovery of log was 84.78% and reached to the maximum. Conclusion: Half-sectional finger joint process could improve the recovery of small-diameter log. The established mathematical model of the ideal log, the mathematical model of log integrated by half-sectional figure joint and the corresponding formula could provide theoretical bases for correlational studies. The recovery of log would be larger with an increasing diameter, which could provide references for actual selection of logs.

Olfaction plays an important role in survival and reproduction of insects. Many proteins from olfactory sensory neurons participate in the olfactory recognition process,including odorant binding protein (OBP),odorant receptor (OR),odorant degrading enzyme (ODE),chemosensory protein (CSP),and sensory neuron membrane protein (SNMP). As an important protein,OR mediates the specific combination of odour molecules and olfactory neurons,which is an important basis for insects to perform olfactory functions. Because the OR structure of insects is different from that of vertebrates,it cannot be obtained by homologous cloning for long time. Thus,ORs discovery of insects has taken a long time. ORs can be divided into two categories. The first category is the functional receptors to recognize various odour molecules,the second one is the receptor without odour molecules recognition function,which co-expresses with other functional receptors to perform olfactory functions together. Researches on OR mainly focus on its identification and functional exploration. At present,there are three expression systems in vitro commonly used in the functional analyses of OR,including the Xenopus oocyte expression system,the heterologous cell expression system,and the Drosophila empty neuron expression system. As for in vivo methods for researching the gene functions,RNAi (RNA interference,RNAi) and Crispr/Cas9 (clustered regularly interspaced short palindromic repeats/Crispr-associated sequence) systems have also been used to explore the OR's function in some insects. Researches on the mechanism of insects OR mainly focus on some model insects. Although forest insects are important insects,their OR research started late. At present,researches about OR in forest insect are mainly gene identification,and only few work is on gene function. The research on the olfactory receptor mechanism provides a good direction for pest control,and it is worth to further strengthen researches about the mechanisms and pest control methods based on olfactory regulation.

Objective: To provide a theoretical basis for the protection,sustainable utilization and the formulation of restoration strategies of Vatica mangachapoi population,the structure and dynamics of V. mangachapoi population in Ganshiling,Hainan Island were studied,in order to elucidate the survival status and quantitative dynamics,and to reveal the patterns of regeneration. Methods: A field survey was carried out on V. mangachapoi population in sample plots in Ganshiling,Hainan Island. According to the characteristics of life history of the species and considering the results from previous researches,diameter,height and crown width were divided into classes and population structure was constructed using the classes. The static life table,survival curve,mortality curve,loss rate curve were produced using space to replace time which meant diameter structure instead of age structure. Four functions (survival,accumulated mortality,mortality density,and hazard rate) of survival analysis were used to analyze population dynamics of V. mangachapoi. Time series analysis method was used to predict the age structure of V. mangachapoi population. Results: The population of V. mangachapoi had complete structures of age,height,and crown width,showing the stable development and good regeneration potential. The static life table showed that there were large differences of number of survival trees among different classes. The rate of mortality and loss were both the highest in age class Ⅳ. The population of V. mangachapoi fitted type B₁ of Deevey-Ⅱ. The changes of mortality and loss rate were in similar trends. Four survival curves showed that the population of V. mangachapoi was decline in every stage,suffering from competitive pressures in the middle period. The prediction by the time series analysis showed that the population of V. mangachapoi had a high ability to regenerate and quickly restore to the stable population structure. Conclusion: A large number of seedlings growing in the population of V. mangachapoi made them survive environmental elimination and competition pressure,enabling some individuals survive and grow into the next age class. However,in the middle and young age class,individuals occupy a certain space and environmental resources in the community,and the environmental stress and competition pressure increased substantially,only a few of individuals may grow into the later stage.

Objective: The tree diameter at breast height (DBH) is an important measurement factor in forest survey and forest management evaluation. In this study,the main leaf functional traits of different diameter classes in even-aged stands of Zenia insignis were determined in order to illuminate the relationship between the leaf functional traits and the diameter growth,which aims to provide theoretical basis for selection of excellent germplasm resources and precision nutrient management of Z. insignis. Methods: Principal component analysis (PCA) was used to determine the main leaf functional traits affecting the DBH growth of the even-aged stand of Z. insignis. Results: Firstly,individual leaf area (ILA),specific leaf area (SLA),leaf relative water content (LRWC),leaf carbon content (LCC),leaf nitrogen content (LNC),leaf phosphorus content (LPC),leaf C:N ratio (C/N),leaf C:P ratio(C/P),leaf N:P ratio(N/P),leaf nitrogen content based on area (N_area),and leaf area phosphorus content based on area (P_area) differed significantly among different diameter classes. Secondly,leaf structural traits,such as ILA and LRWC,and leaf functional traits,such as P_area,C/P,LPC and N/P,had important impact on the DBH growth. ILA and P_area showed a significant linear positive correlation with the diameter growth (P < 0.01). LRWC and leaf N/P showed a significant linear negative correlation with the DBH growth (P < 0.01). There was a quadratic parabola relationship between leaf C/P and DBH growth,showing increase after slightly decrease (P < 0.01). Whereas there was a quadratic parabola relationship between LPC and the DBH growth,showing decrease after slightly increase (P < 0.05). Thirdly,the correlations between SLA,N_area,LCC,LNC and C/N were not significantly correlated with the DBH growth. Conclusion: Leaf structural and functional traits have important effects on the DBH growth of Z. insignis. ILA in structural traits as well as LPC and P_area in functional traits are the most important influencing factors.

Objective: In this study,we investigated the response of the growth and cell ultrastructure of poplar cutting seedlings to high temperature,drought and their combined stresses,in order to explore the relationship between leaf morphology,growth and ultrastructure damage under stress and thereby reveal the differences of the response mechanism of poplar to different stresses from morphological and cytological perspectives. Methods: Cuttings of Populus×euramericana 'Nanlin-895' poplar were used as the experimental material. Different temperature and moisture gradients were set to study the growth and morphological indexes of poplar under single factor stress and combined stress of high temperature and drought,and the effects of different treatments on cell ultrastructure were investigated under TEM. Results: 1) Compared to the control,the basal diameter,seedling height,biomass and partitioning index of leaves decreased while leaf perimeter to area ratio,the ratio of root to shoot,partitioning indices of root increased under single or combined stress of high temperature and drought. The effects of combined stress on growth morphological index were greater than those of the single stress. 2)Ultrastructure of leaves was damaged to different degrees under single or combined stress of high temperature and drought. Chloroplast swelled,and lamella structure expanded or even melt,osmiophilic granules content increased and starch granule content decreased,and even the arrangement of mesophyll cells was disorganized with damaged membrane structure under severe stress. The damage intensity of leaf ultrastructure was consistent with the stress level. Severe high temperature stress produced more obvious impact on ultrastructure than drought stress. The effects of combined stress on ultrastructure were greater than those of single stress. Conclusion: Under high temperature and drought stress,the damage of ultrastructure of leaves affects the photosynthesis and the stability of the intracellular environment. Normal physiological processes are affected,and eventually results in the changes of seedling growth morphology.In this study,destruction of cell ultrastructure was consistent with the performances of growth morphology,which indicates the feasibility of revealing the response mechanism of plants to stress by cytology and morphology indicator analysis.

Objective: Populus euphratica is an important tree species in arid areas,the species is of great significance for maintaining the ecological environment stability in arid areas. The paper tries to identify the dominant environmental variables that limit the distribution of P. euphratica, and to predict its suitable distribution area,in order to provide a theoretical basis for the protection and restoration of the species. Methods: The geographical information of 226 existing occurrences of P. euphratica and four types of environmental variables,including climate,topography,soil and hydrology were analyzed using the MaxEnt ecological niche modeling to simulate the potential suitable distribution areas for the species. Evaluation of credibility of the MaxEnt model,comparison of the accuracies of simulation using single climate variable and four types of environmental variables,and identification of the environmental variables limiting the distribution of the species were carried out with combination of method of the receiver-operating characteristic curve (ROC),the jack knife,the percent contribution of the environment variables and the permutation importance for the analyses. Results: 1) The area under the receiver-operating characteristic curve (AUC) showed that the training data of the single climate variable and four types of environmental variables was 0.983±0.002 and 0.982±0.001,respectively. The test data was 0.980±0.006 and 0.967±0.009,respectively. It indicated that two different quantitative data sets had less influence on AUC value and the simulation performed well with a very high credibility. 2) The percent contribution,permutation importance and jack knife showed that the simulation with the four types of environmental variables could identify more effective environmental variables affecting the distribution of P. euphratica. The geographical distribution of the species was affected by precipitation of the driest month and the warmest quarter,the soil moisture content (10-40 cm underground),the soil moisture around root system and the evapotranspiration of soil water. 3) The simulated potential suitable area based on climate variable expanded by 4.33 times compared to that on the four types of environmental variables. The simulation based on the four types of environmental variables reflects more details of distribution such that along riverbank. 4) The suitable distribution area simulated by the MaxEnt model was much larger than the actual distribution area,implying great potential for development of plantations of P. euphratica. Conclusion: The distribution of P. euphratica is affected by many environment variables. There is large deviation between the simulated distribution area using only climate variable and the actual distribution range of this species. The simulation based on four types of environmental variables reflects more characteristics of the actual distribution. This study provides a theoretical basis for the protection and restoration of the degraded P. euphratica forest.

Objective: This study aims to clarify the effects of different cultivation methods on the growth of four poplar Aigeiros Section clones as well as their resistance to drought stress and defoliator of Apocheima cinerarius (Lepidoptera:Geometridae) to explore a forest cultivation method that raises the poplar with fast growth,drought resistance and pest resistance,in order to provide a reference for improving the poplar plantation quality. Methods: In March 2013, four poplar Aigeiros section clones (P.×euramericana cv. Guariento,P.×euramericana cl.N3016,P. deltoides cl. Nanyang and P. deltoides cl. Danhong) were planted in the forest farm of Mengzhou,Henan Province with different cultivation methods of pure or mixed forests. The effects of different cultivation methods on the growth rate,survival rate and population density of A. cinerarius,an important leaf eating insect of poplar,were evaluated through sampling survey. In the case that some clones died due to severe drought in 2013,P.×euramericana cv. Guariento with strong drought resistance were used to replenish the planting in each plot in March 2014, and then the growth status of P.×euramericana cv. Guariento forest and its mixture with other clones and their insect resistance were investigated. Results: There was no significant difference in the annual mean tree growth rate and annual mean DBH growth rate of the five treatments during 2013-2016. After the replantation with P.×euramericana cv. Guariento,the height and DBH of P. deltoides cl. Danhong and P. deltoides cl. Nanyang were significantly greater than that of P.×euramericana cl.N3016 in 2016. The annual survival rate of P.×euramericana cv. Guariento and P.×euramericana cl.N3016 was significantly higher than that of P. deltoides cl. Danhong and P. deltoides cl. Nanyang in 2013 (P < 0.05). The main pest was A. cinerarius. In the three years,the damage rate of five forests and the population density of A. cinerarius from high to low respectively was:P.×euramericana cv. Guariento,P.×euramericana cl.N3016,mixed planting,P. deltoides cl. Nanyang and P. deltoides cl. Danhong. After replanting with P.×euramericana cv. Guariento,the damage rate and the insect population density of P.×euramericana cv. Guariento,P.×euramericana cl.N3016 and their plots were significantly reduced. However,there was no significant difference in the damage rate and insect population density between P. deltoides cl. Nanyang,P. deltoides cl. Danhong and their plots during three years. In addition,the damage rates of the plots of P. deltoides cl. Nanyang and P. deltoides cl. Danhong mixed with P.×euramericana cv. Guariento respectively were significantly lower than that of the plots of four clones mixed planting,and the damage rate and insect population density of the replanting of P.×euramericana cv. Guariento in P. deltoides cl. Nanyang and P. deltoides cl. Danhong plots were significantly lower than that in P.×euramericana cv. Guariento and P.×euramericana cl.N3016 plots in 2015 (P < 0.05). Conclusion: The study reveals that P.×euramericana cv. Guariento,P. deltoides cl. Danhong and P. deltoides cl. Nanyang should be used as suitable species for poplar plantation. Although P.×euramericana cv. Guariento has high damage rate,but it has high survival rate and strong drought and pest tolerance. P. deltoides cl. Danhong and P. deltoides cl. Nanyang have high pest resistance and good growth traits. P.×euramericana cv. Guariento mixed with P. deltoides cl. Nanyang or P. deltoides cl. Danhong can promote growth and improve resistance to insect pest.