Objective: To provide a theoretical basis for biodiversity conservation and ecosystem restoration,a study of phylogenetic structure of the undergrowth tree,shrub,and herb layers and their driven ecological processes were conducted across different successional forest communities in the subalpine area of western Sichuan. Method: We used inventory data of tree-shrub-grass species compositions of the undergrowth layers in the subalpine forests,which consists of primary dark coniferous forests(hereafter primary forest) and their secondary forests(hereafter secondary forest) after harvesting in the period 1950 to 1969 and 1970 to 1989. We ignored canopy layer because tree species compositions in this layer were relatively simple. A phylogenetic tree of the understory plant species was rebuilt based on the APG Ⅲ phylogenetic framework for different successional forest communities. Two widely selected phylogenetic diversity indices,net relatedness index(NRI) and nearest taxon index(NTI),were used to quantify and assess the phylogenetic structure of different undergrowth layers and their driven ecological processes during forest succession. Result: For primary forest,a phylogenetic over-dispersion pattern(i.e.,NRI < 0; NTI < 0) was shown in the sub-canopy layer,suggesting that distantly related species coexist in this layer. In contrast,a phylogenetic clustering pattern(i.e.,NRI > 0; NTI > 0) was displayed in the other three layers(i.e.,herb,shrub and small tree),which implies that close related species consist of these layers. The two secondary forests formed in different deforestation phases showed a consistent phylogenetic pattern in the herb layer(i.e.,phylogenetic over-dispersion),which was contrary to that in the sub-canopy layer(i.e.,phylogenetic clustering). However,the shrub and small tree layers showed a similar pattern but inversely expressed on the two secondary forests,which were phylogenetic clustering in 1950—1969 regenerated forest and phylogenetic overdispersion in 1970—1989 regenerated forest. The relationships between NRI and NTI of the undergrowth layers were significantly positive for both primary and secondary forests. Pearson correlation analysis showed that Shannon's diversity index(H') and NRI or NTI were neither significant across undergrowth layers nor across different successional forests. However,the local polynomial regression fitting revealed that the correlations between H' and NRI or NTI displayed identical peak-and-trough changing patterns on primary and 1970—1989 secondary forests. Conclusion: The phylogenetic structure is different across undergrowth layers as well as across primary forests and their secondary forests with different deforestation phases. Environmental filtering is a main ecological process influencing species compositions in the herb,shrub and small tree layers,whereas competitive exclusion has a greater force in constructing phylogenetic assembly of the sub-canopy layer. For secondary forest,the phylogenetic structure of undergrowth layers and their underlying ecological processes are mainly opposite to those in primary forest,that is environmental filtering determines phylogenetic structure of the sub-canopy layer and competitive exclusion determines species compositions of the herb layer. Phylogenetic diversity is independent with species diversity for undergrowth layers across different successional forests in the subalpine of western Sichuan.

Objective: The vegetation and shape characteristics and spatial distribution of Nitraria tangutorum Nebkhas in different developmental stages were studied to characterize the spatial point distribution and patterns of variation of N. tangutorum Nebkhas with the increase of size of the sandpiles in order to reveal the characteristics of community formation and the mechanism of maintaining ecological patterns of N. tangutorum Nebkhas during the development process. Methods: Based on field investigation,four typical sample plots of N. tangutorum Nebkhas in 4 different developmental stages,i.e,prototype,developing,stabilizing,and activating,in Minqin desert-oasis ecotone were selected. In light of the two-dimensional coordinates,the N. tangutorum Nebkhas were graded into 3 classes,i.e. small,medium and large,respectively,according to the volumes of sandpiles. Their spatial distribution were analyzed with the univariate O-ring function while the correlation among different grades of the sandpiles at different scales was determined by the bivariate O-ring function under the quantitative statistical methods. Results: With the development of the sandpiles,the overall growth changed from good to poor,and the vegetation coverage tended to increase at the beginning and followed by a decrease,which was 51.4% at the prototype stage,reached to the highest 68.8% at the stabilizing stage,then decreased to 60% at the activating stage,whereas the bush deadwood rate showed an opposite trend,which increased from 15% at the prototype stage to 27% at the activating stage. Different distribution patterns appeared for different grades of sandpiles at different scales. At the prototype stage,they tended to be evenly distributed under the scale of 0-5 m,and randomly distributed on the scale of 2-25 cm,whereas distributed in aggregate under the scale of >25 m; at the developing stage,they tended to be uniformly distributed under the scale of 0-5 m,but were randomly distributed under the scale of 5-30 m; at the stabilizing stage and activating stage,they showed a uniform distribution under small scales(< 5 m),a random distribution under the scales >5 m,respectively. The sandpiles of different sizes at different developmental stages showed different association with changing scales. For the small grade sandpiles(grade 1 and 2),except that there was no correlation between the small sandpiles(grade 1 and 2) at the developing stage,it was positively correlated with each other in small sandpiles(grade 1 and 2) along with the increasing spatial scale in other different stages. For the grades 2 and 3,their spatial correlations with other sandpiles showed as a negative correlation under the scale of < 10 m,whereas there were gradually strengthen negative correlation or even disappearing with increasing scales under the scale of >10 m. Conclusion: The sandpiles of N. tangutorum Nebkhas showed no significant aggregation although the different grades of sandpiles at different development stages have different proportions in each sample plot. With the gradual progress of the sandpile development,large sandpiles tended to be randomly distributed,but,the correlations between the small sandpiles grades showed positive on the small scale,while,the negative correlations appeared strengthen or uncorrelated on the medium and large scales,indicating the composition and structure of the sandpiles of N. tangutorum Nebkhas community become less stabilized as the development progresses.

Objective: In this study,5-year-old European spruce(Picea abies) seedlings were used to evaluate the thermal stability and self-repairing ability of PSⅡ in the future climate warming. Method: Three clones,10 ramets of each clone,30 ramets in total,were selected and cultured in an artificial climate chamber under normal conditions. Two weeks later,hand-PEA and image-PAM were used to detect the fluorescence parameters and image of leaves as control. After preheating for 5 hours in a low light incubator at 38℃,seedlings were heated for 30 minutes at 40,42,43,44,46,48,50,52,53 and 54℃,respectively. Three clones(one ramet per clone) were treated in each experimental group. Hand-PEA and image-PAM were used to detect the fluorescence parameters of leaves and two critical temperatures of tress were selected. Seedlings treated under two critical temperatures were cultured in an artificial climate chamber for two weeks. Hand-PEA and image-PAM were used to detect the fluorescence parameters and images of leaves,and to study the self-repairing ability of spruce PSⅡ after heat shock. Result: 1) Through the study of Y(Ⅱ),Y(NO) and Y(NPQ) fluorescence images and kinetic curves,it was found that under 44 ℃ heat stress,PSⅡ of P. abies reached the initial stress temperature,and under 52 ℃ heat stress,it reached the maximum stress temperature. Compared with herbs,other woody species and related species,the thermal stability of PSⅡ was at a higher level for P. abies. 2) The fluorescence parameters of F₀,F_m,F_v/F_M,NPQ,q_L and q_P of PSⅡ and the fluorescence kinetic parameters of NPQ,q_L and q_P were detected by image-PAM at critical temperature: the fluorescence kinetic parameters of F_m and F_v/F_m were weakened,the fluorescence images of q_L and q_P were enhanced,and the fluorescence kinetic parameters of NPQ,q_L and q_P were higher than those of the control at 44 ℃. The fluorescence kinetic curves of F_v/F_m,q_L and q_P were lower than those of the control. 3) The hand-PEA was used to further detect the change of fluorescence parameters of PSⅡ. Under 44 ℃ short-time heat shock,F_v/F_m and OJIP curves did not change significantly,PI_ABS decreased only to 79.5% of the control group. The ability of chlorophyll(Chl) to absorb and capture light energy,the transmission of electrons,and the activity of center protein in electron transfer chain were not significantly inhibited. The heat chock also promoted the ability of Chl to absorb energy(ABC) photochemical reaction and fluorescence quenching. However,under the short-term heat shock of 52 ℃,the function of PSⅡ was obviously inhibited,and the OJIP curve also showed a large "K" band,F_v/F_m was reduced to 63.2% of the control group. PI_ABS was only 6.6% of the control group. The absorption and capture of light energy,photochemical reaction,fluorescence quenching and electron transfer ability of chlorophyll(Chl) were severely inhibited at the moment of F_m,and the oxygen evolution complex(OEC) of electron transfer chain was also severely damaged. Therefore,it was predicted that increasing temperature mainly inhibited the activity of reaction center and electron transfer on receptor side of PSⅡ in leaves,changed the energy flow and distribution in PSⅡ reaction center. But it had little effect on the donor side of PSⅡ. 4) After two weeks of recovery in normal growth condition,the fluorescence parameters and images of the needles of the seedlings that were previously subjected to heat shock under the two stress temperatures were restored to the level of the control,indicating that P. abies had a strong recovery ability to the short-term stress. Conclusion: Therefore,we predict that PSⅡ of P. abies has a strong elastic adaptation physiological mechanism to cope with the short-term high temperature in extreme weather at noon under the future climate change,and its temperature range of heat shock stress can be withstood that is 44-52 ℃.

Objective: Phosphoenol pyruvate carboxylase(PEPC) and phosphopyruvate dikinase(PPDK) are the key enzymes to ensure efficient photosynthesis in C₄ plants. Poplar,as a C₃ plant with low photosynthetic efficiency,has low light energy utilization. In this study,maize PEPC gene and PPDK gene were used as target genes for genetic transformation in poplar,respectively,to obtain highly expressed transgenic plants,and molecular detection and functional analysis were carried out to provide a basis for breeding new poplar varieties with high light efficiency. Method: The PEPC and PPDK genes of maize were screened through bioinformatics. With Gateway system,PEPC and PPDK genes were constructed into plant expression vector pGWB406,respectively,and transformed into 'Nanlin 895' poplars(Populus deltoides×P. euramericana 'Nanlin 895') by Agrobacterium-mediated transformation. The photosynthetic physiological characteristics of transgenic plants and control('Nanlin 895' poplars) were compared and analyzed. Result: The cloned PEPC and PPDK genes all encode typical key enzymes of C₄ photosynthesis. There were 5 lines transformed with PEPC gene and 3 lines transformed with PPDK gene. There were differences in gene expression among different lines of PEPC gene,up to 1.79 times,but there was no significant difference in the expression of proteins in leaves of different lines,and no significant difference in gene and protein expression among lines of PPDK gene; the expression of the two genes in leaves were higher than that in stems,and increased with time during plant growth and development; the expression of PEPC gene and PPDK gene were affected by light conditions,and increased 2-3 times under high illumination; the net photosynthetic rate of the transgenic lines showed a double peak at 11:00—14:00,which were significantly higher than that of the control group,with a maximum of 16.2%(PEPC-5 line); the stomatal conductance were higher at 12:00—16:00 than that of the control group; except PPDK-2 line,higher intercellular CO₂ concentrations were detected in all transgenic lines than in the control group,and except for PEPC-1 and PEPC-4 lines,the CO₂ saturation points of the transgenic lines were lower than that of the control group; the CO₂ compensation points of all transgenic lines were lower than that of the control group,and the photosynthetic rate at light saturation point and light saturation point were higher than that of the control group. The growth parameters of PEPC-3 and PEPC-4 lines were significantly larger than those of the control group(P < 0.05). The average tree height was 5.6% and 2.9% higher than that of the control group,the leaf area was 13.8% and 8.9% higher than that of the control group,the leaf weight was 23.6% and 19.8% higher than that of the control group,and the ground diameter was 13.5% and 5.4% higher than that of the control group,respectively. The leaf biomass measurements showed that the dominant lines were PEPC-3,PEPC-5 and PEPC-4,which were 34.8%,15.4% and 6.3% higher than those of the control group respectively. Conclusion: The introduction of PEPC and PPDK genes made the transgenic plants have obvious advantages in light utilization,significantly improved the photosynthetic capability of the plants,and the growth performance was better than that of the control group. The genetic transformation of poplar using the key enzymes coding genes of photosynthesis in C₄ plants is of great significance for improving the photosynthetic efficiency of poplar and even other woody plants.

Objective: Tubulin is an important component of plant cytoskeleton and plays an important role in plant cell division and growth,cell morphology maintenance,intracellular material transport and cell wall biosynthesis. In order to comprehensively understand the molecular characteristics of tubulin in Moso bamboo(Phyllostachys edulis),the genome-wide identification and analysis of tubulin were carried out,and the gene function of PeTUA3 was preliminarily studied,intending to provide evidences for revealing the role of tubulin involved in the growth and development of Moso bamboo. Method: A genome-wide analysis of tubulin genes in Moso bamboo was conducted using bioinformatics method. The tissue expression patterns of tubulin genes and their expression changes with increasing shoot height were analyzed by transcriptome data and real-time fluorescence quantitative PCR(qPCR) respectively. The function of PeTUA3 was preliminarily studied by ectopic expression in Arabidopsis thaliana followed by phenotypic observation. Result: A total of 18 tubulin gene sequences were obtained from the Moso bamboo genome,which encoded proteins with complete conserved domains of tubulin. The length of these proteins ranged from 430 aa to 634 aa with the molecular weight of 48.31-69.89 kDa. In the phylogenetic tree constructed with tubulins of Oryza sativa and A. thaliana, they were clustered into two subfamilies(TUA and TUB),and those members of Moso bamboo were closer to those of rice,which were named as PeTUA1-PeTUA6 and PeTUB1-PeTUB12, respectively. Subcellular localization prediction showed that all the PeTUAs were localized in the cytoplasm,while all the PeTUBs were localized in the nucleus. Gene-specific expression analysis based on transcriptome data showed that there were some differences in the expression levels of different tubulin genes in seven different tissues of Moso bamboo. For example,the expression levels of PeTUA3, PeTUA6, PeTUB2 and PeTUB3 were higher in each tissue,while those of PeTUA2 and PeTUB12 were lower in all the tissues. The qPCR demonstrated that with the increasing height of bamboo shoots,all the expression of the members in TUA subfamily was upregulated,while 8 genes in TUB subfamily showed upregulation trend,and 4 genes with fluctuations,indicating they may play different roles in different developmental stages of bamboo shoots. The expression of sense PeTUA3 in A. thaliana promoted the growth of transgenic plants,especially the elongation of the main roots,while that of antisense PeTUA3 inhibited the growth of transgenic plants,and the growth of the main roots was inhibited significantly. Conclusion: Six TUA genes and 12 TUB genes were identified in Moso bamboo. The molecular characteristics of each tubulin gene were different,and the expression of each gene in different bamboo tissues and shoots at different developmental stages showed different patterns,indicating that they may play different functions in different tissues and different growth stages of the same tissue. Overexpression of PeTUA3 could affect the growth of transgenic A. thaliana plants,suggesting that PeTUA3 may play an important role in the rapid growth of bamboo.

Objective: Population genetic diversity and genetic structure of Disanthus cercidifolius var. longipes were analyzed,and its population demographic history was speculated,so as to deepen understanding on its evolutionary process,and to provide a theoretical basis for conservation and utilization of its genetic resources. Method: Genetic diversity of 261 individuals from 12 natural populations of the species were estimated at 15 polymorphic loci using TP-M13-SSR technology. All sampled individuals were genotyped using Gene Marker,genetic parameters were assessed with FSTAT,analysis of molecular variance was carried out with ARLEQUIN,Bayesian clustering analysis was conducted for all sampled individuals with STRUCTURE,and genetic bottleneck effect was detected by Bottleneck software. Result: A total of 129 alleles were detected at 15 loci,and the mean allele number and effective allele number at each locus were 8.6 and 3.5,respectively. The mean observed heterozygosity and expected heterozygosity were 0.37,0.67. At population level,the mean allele number and effective allele number were 3.4 and 2.1,the mean observed heterozygosity and expected heterozygosity were 0.35 and 0.43,respectively. The private allelic richness and within-population inbreeding coefficient were 0.15 and 0.19,respectively. All populations deviated significantly from HWE with an excess of homozygotes except DX population. The genetic differentiation between populations was statistically significant(P < 0.001). All the populations were classified into two clusters,and the lineages of most individual were clear. The populations had not experienced genetic bottleneck events over the historical evolutionary process. Conclusion: Our results demonstrated that D. cercidifolius var. longipes maintained a moderate to high genetic variation,and the habitat fragmentation and genetic drift has not yet declined within-population genetic diversity. This species has high evolutionary potential. The geographic isolation,habitat fragmentation caused by climate change and human disturbance might be the main causes for the formation of current geographical distribution pattern and population genetic structure. Overall,our study provides scientific evidences for making effective conservation strategies for the species.

Objective: The aim of this study is to explore the roles of Bursaphelenchus xylophilus (pine wood nematode,PWN) and the bacteria associated with PWN in the development of pine wilt disease (PWD),to provide theory gist for research on PWN pathogenic mechanism and PWD prevention. Method: Five-year-old healthy Pinus massoniana seedlings grown in green house were artificially inoculated with aseptic PWNs and non-aseptic PWNs,including 8000 PWNs per seedling,and then the status of seedling wilting was observed. The cross section was taken to detect the resin secretion after 5,10 and 30 days of inoculation. The anatomical structure of stem section was observed under a microscope after 20 days of inoculation. The PWNs were re-isolated from wilting seedlings after 30 days of inoculation. Result: Both aseptic PWNs and non-aseptic PWNs wilted 5-year-old seedlings of P. massoniana, expressing similar symptom.The wilting rate reached 90% after 35 days of inoculation,while the control seedlings remained healthy. The observation of cross sections showed that resin stopped secreting after 5 days of aseptic PWNs inoculation,a small amount of cavities began to appear after 10 days,and serious cavitation appeared after 30 days. The observation of cross sections showed that resin decreased secretion but not stopped yet after 5 days of non-aseptic PWNs inoculation,the secretion stopped after 10 days and cavities formed after 30 days. While the control pines secreted normally resin and there is no cavity in their stems. The results of paraffin section showed that the histological and anatomical structure of the stem segments of wilted seedlings changed remarkably in the both treated groups. Most of the cells,in cortex,xylem and pith,were deformed and the epithelial cells near the resin canal were broken and disintegrated. The multiplication rate of aseptic PWNs in wilted seedlings was higher than that of non-aseptic PWNs. The average number of nematodes re-isolated from wilted seedlings was (8 105±5 661)·g^-1 for aseptic PWNs and (4 317±1 896)·g^-1 for non-aseptic PWNs,with no significant difference between the two groups (P = 0.3619). Conclusion: Both of the aseptic and non-aseptic PWNs are able to infect P. massoniana. Asepsis does not make PWNs lose their pathogenicity on P. massoniana. PWNs are necessary factor in the PWD development while,the pathogenicity has nothing to do with the associated bacteria.

Objective: This paper aims to study the taxonomic status of endophytic actinomycete A-m1, optimize its fermentation conditions, and clarify its antibacterial activity and antibacterial spectrum against pathogens such as apple diseases, and provide biological control for related diseases and further application of the strain. Method: The colony culture characteristics, morphological observation, physicochemical properties and 16S rDNA sequence of strain A-m1 were studied. The basic medium for the highest antibacterial activity was determined by using Botryosphaeria dothidea as the target bacteria, and the types of carbon source and nitrogen sources were optimized. The optimal fermentation conditions were determined; the antibacterial activity of the fermentation filtrate against the nine tested pathogens was determined. Result: The strain A-m1 was identified as Streptomyces rochei by combining morphology, physiological and biochemical characteristics and 16S rDNA molecular identification. The basic medium required for high bacteriostatic activity was Gause 1 cultural medium, the best carbon source was soluble starch, the optimum nitrogen source was potassium nitrate. The optimal fermentation conditions were: adding 5% seed solution of medium volume, the fermentation temperature of 23-32 ℃, pH of 6-8, the liquid volume of 100/500 mL, and fermentation culture for 4 days. The fermentation filtrate showed antibacterial activity against the 9 plant pathogens tested, showing the broad-spectrum of antibacterial activity. Among them, the antibacterial activity of the fermentation filtrate against B.dothidea and Phomopsis mali was more than 95%, and the inhibition rate against Colletotrichum gloeosporioides, Fusarium graminearum and Rizoctonia cerealis was over 80%. Conclusions: S. rochei A-m1 has a broad spectrum of antibacterial activity and high antibacterial activity, and has the potential for controlling fungal diseases of some crops.

Objective: This study aims to investigate the fungal groups associated with pest Agrilus mali (Coleoptera: Buprestidae) in the wild apple (Malus sieversii) forests in Xinjiang and their diversity, and to study the death of trees caused by A. mali and the associated fungi altogether. Method: The strains of the associated fungi were obtained by isolating the tissues of the beetle larvae, pupae, adults and galleries. The identification was conducted based on the molecular data. The diversity of the associated fungi was analyzed using the statistical and graphic software. Result: The result showed that totally 57 genera of the associated fungi, belonging to six classes and eighteen orders, were isolated. Among them, 40 genera were isolated from galleries, 37 genera from adults and 34 genera from larvae+pupae, respectively. As a whole, Alternaria is the dominant genus for all experimental materials, with the relative abundance of 30.58%, followed by Fusarium which was 13.8%. In terms of the isolation materials, Alternaria was also the main group from the adults, Dothiorella was the main group from the larvae+pupae, and Cytospora was the main group from the galleries, with the relative abundance 50.30%, 13.91% and 16.96%, respectively. Besides, in the three experimental materials, the β-dissimilarity index of the fungi from the larvae+pupae and adults were the highest (Jaccard dissimilarity index=0.608, Bray-Curtis dissimilarity index =0.683); the two dissimilarity indices of fungi from the adults and galleries were quite different (Jaccard dissimilarity index = 0. 490, Bray-Curtis dissimilarity index = 0.609); Shannon-Wiener index (H' = 2.949 6) and Richness index (R = 7.206 7) of the fungi from the galleries were the highest, while Pielou index (J=0. 830 2) of the fungi from the larvae +pupae was the highest; adults fungi population diversity index (H' = 2.012 8), Pielou index (J=0.557 4) and Richness index (R=6.214 4) were the lowest, indicating that the adult carried relatively less diverse fungi, however, the proportions of several main fungi species were significantly different among the whole associated fungal groups. Conclusion: The associated fungi of A. mali are diverse, with the various compositions and numbers on three experimental materials. For four main associated genera fungi, Fusarium usually leads to branches withered and rot of their host plants, while Dothiorella and Cytospora cause plants canker. Therefore, we suggest that the wild apple trees are likely endangered by both A. mali and its associated fungi above western Tianshan Mountains in Xinjiang. The result provides insights to the communities and structures of the associated fungi of A. mali. In addition, the findings would be helpful to establish the effective management strategy of the pest insect.

Objective: The effects of different host tree species, on which Batocera lineolata larvae fed, on adult behavior and the internal mechanism were discussed based on the comparisons of the supplementary nutritional behavior, morphological characteristics and genetic traits of B. lineolata adults. Method: B. lineolata adults emerged from host trees of Populus tomentosa and Fraxinus pennsylvanica were collected respectively. The external morphology and male genital structure of B. lineolata adults from the two host plants were observed and compared. Then, through the feeding preference experiment, the feeding behavior and mating behavior of these two kinds of adults on the shoots of five plant species, i.e. Rosa multiflora, Carya illinoinensis, Viburnum odoratissimum var. awabuki, F. pennsylvanica and P. tomentosa were observed. The interactive mating tests were conducted between B. lineolata adults from the two host plants. Finally, mitochondrial cytochrome c oxidase subunit I(COI) gene sequences of the two populations of B. lineolata were cloned by universal primer, and the sequence differences and phylogenetic relationships were analyzed based on COI gene. Result: 1) There are obvious differences in external morphology between the two B. lineolata beetles whose larvae fed on P. tomentosa and F. pennsylvanica, respectively. The bottom of abdomen of the male adults emerged from F. pennsylvanica is narrow, in obtuse angle, inward-concave and covered with sparse hairs, and the bottom of the female adults is curved-concave, and the central indentation of the bottom is not obvious. However, the bottom of abdomen of the male adult from P. tomentosa is wide, curved, inner-concave and covered with dense hairs. And the bottom of the female adults is flattened and the central indentation of the bottom is obvious. The genital morphological characteristics of the two beetles are similar. 2) B. lineolata adults from F. pennsylvanica only consumed the fresh branches of F. pennsylvanica, and B. lineolata from P. tomentosa fed on three plant species, and preferred order was R. multiflora > C. illinoinensis > V. odoratissimum var. awabuki; 3) Male and female adults from different host plants were able to mate with each other, and the mean mating bouts was equal to that of male and female adults from the same host plant(P > 0.05); 4) Analysis of molecular variation(AMOVA) for COI genes indicated a significant genetic differentiation between the two B. lineolata populations(F_st =0.813 85, P < 0.001), and most of the genetic variance was among populations(81.39%) rather than within populations(18.61%). Conclusion: Larval feeding experience(feeding on different host plants) and habit differentiation can significantly affect feeding behavior of B. lineolata adults and genetic variation of populations.

Objective: The study on the pyrolysis characteristics of forest fuel can help us to understand the difficulty level of forest fire occurrence and the characteristics of potential fire behavior, which is of great significance for the rational selection of fire-resistant tree species and the construction of biological fire-resistant forest belt. In this paper, the pyrolysis process of forest fuel in Bilahe forest area in Daxing'an Mountains of Inner Mongolia was obtained by thermogravimetric analysis in order to select the tree species with good fire resistance. Method: Thermogravimetric analysis was used to study the thermogravimetric behavior of five typical tree species in Bilahe forest area: Populus davidiana, Larix gmelinii, Betula dahurica, Betula platyphylla, Quercus mongolica (trunks, barks, branches) and surface dead fuel (undecomposed layer, semi-decomposed layer and decomposed layer), and three typical shrub species: Corylus heterophylla, Rhododendron dauricum, Lespedeza bicolor (twigs) under the conditions of heating rate of 30℃·min^-1 and oxygen flow rate of 20 mL·min^-1. TG-DTG curve was used to analyze the pyrolysis process, Coats-Redfem integration method was used to conduct the kinetic analysis of the rapid pyrolysis stage, the pyrolysis characteristic index P was used to comprehensively evaluate the pyrolysis characteristics, and the activation energy, ignition temperature and pyrolysis characteristic index were used to comprehensively analyze the fire resistance. Result: The pyrolysis process of forest fuel under air atmosphere can be divided into dehydration stage, rapid pyrolysis stage and carbonization stage. The activation energy (E), frequency factor (A) and correlation coefficient (R) of forest fuel during the rapid pyrolysis stage can be calculated by Coats-Redfem integration method of the first-order reaction kinetics model. Combing the comprehensive analysis of thermal stability, ignition temperature and pyrolysis characteristic index, the fire resistance of five tree species was Larix gmelinii > Betula platyphylla > Betula dahurica > Populus davidiana > Quercus mongolica. The fire resistance of three shrub species was Corylus heterophylla > Lespedeza bicolor > Rhododendron dauricum. The fire resistance of surface dead fuel of five tree species was Larix gmelinii > Betula platyphylla, Betula dahurica > Populus davidiana, Quercus mongolica. Conclusion: The fire resistance of Larix gmelinii and Corylus heterophylla are the best among the selected samples. The results can provide theoretical basis for decision-making of selection of fire-resistant tree species in Daxing'an Mountains, Inner Mongolia.

Objective: In this paper, Robinia pseudoacacia was taken as the research object, and the physical and mechanical properties such as density, compression strength parallel to grain, bending strength and bending modulus of elasticity of branches, stems and roots of R. pseudoacacia at different ages were studied. We used the SEM image and chemical composition to explain the intensity difference of branches, stems and roots wood in order to enhance the added value and to provide theoretical supports and experimental bases for improving the comprehensive utilization rate of branches, stems and roots. Method: The physical and mechanical properties such as density, compression strength parallel to grain, bending strength and bending modulus of elasticity of branches, stems and roots of R. pseudoacacia at different ages were determined, as well as the SEM images and chemical composition. Result: The air-dry density of R. pseudoacacia in one tree was classified as branches > stems > roots. With the increase of age, the density of branches, stems and roots increased, but the extent of increase was small. The air-dry density of the branches of R. pseudoacacia was slightly higher than medium density, and the air-dry density of stems and roots was medium density. The compression strength parallel to grain, bending strength and bending modulus of elasticity in one tree were all classified as stems > branches > roots. With the increase of tree age, the compression strength parallel to grain, bending strength and bending modulus of elasticity of branches, stems and roots of R. pseudoacacia increased, but the extent of increase was small. There was a positive correlation between cellulose content and mechanical strength, and lignin content was negatively correlated with mechanical strength. The content of cellulose in roots was larger than that in branches and stems. Conclusion: The stems of R. pseudoacacia above 10 years old can be used as timber structure of load-bearing wood; the mechanical strength of the branches is slightly lower than that of the stems, it can be used as a general structural material in the case of meeting the requirements of the size of the timber; the roots can be used as a small size decorative structural material. Roots of R. pseudoacacia has a high content of cellulose, which can be used to make medium density fiberboard.

Objective: In the paper, testing in the full size structural beam connected with a dowel (drift pin) to the slotted-in steel plates in the loading direction of perpendicular to the grain of the beam was done to study the failure mechanisms and load-bearing performances of the dowel joint of Japanese cedar beam. The research was conducted to provide basic data for the design of dowel joint at the end of the beam in the post and beam structure. Method: After slotting and drilling at the end of the beam, a single dowel was connected to the slotted-in steel plates. The bending shear testing under load perpendicular to the grain was carried out on the Japanese cedar beam of sawn timber and glued laminated timber (glulam) in the same size, respectively. According to the general analysis method in Japan, standard percentile values of load-bearing in the short term of dowel joint in the beam were determined, and compared with the calculated values based on the yield load specified in 5 different national standards. Result: In the initial loading, the load-displacement curve had a linear relationship in a linear elastic stage. As the displacement increased, the curve became nonlinear and entered the elastoplastic stage. When the displacement increased to a certain value, initial brittle cracking occurred at the end of the beam, and the load was suddenly reduced rapidly, and then the load rose again. When loaded to the limit state, the beam member split and lost its bearing capacity. Cracks along the horizontal shear plane of the pin hole in the beam component happened with yield mode Ⅲ in the final failure. The standard percentile value in the short-term bearing capacity of the single dowel joint in the slotted-in steel plates at the end of beam of the sawn timber and glulam beams with a cross section of 120 mm×240 mm depended on the yield load, which was 8.6 kN and 13.7 kN, and the average load value corresponding to the initial cracking was 15.0 kN and 21.1 kN, the average yield load was 14.50 kN and 15.00 kN, and the average maximum load was 27.0 kN and 30.8 kN, respectively. Conclusion: The average value of maximum load and the yield load of a single dowel connection of glulam beams was greater than that of the sawn timber beams, and the coefficient of variation was significantly smaller than that of the sawn timber. The moisture content of glulam beams was relatively low and less variation. The above reasons resulted in the standard value of pin joint load of glulam timber a little higher than that of sawn timber, i.e. a higher connection bearing capacity. When the dowels were used as the main type of connectors for post and beam components, glulam with certificated strength grades as the wood component might be preferable to sawn timber. The bearing capacity of the pin connection in the beam end had a good correlation with the bearing capacity of the single pin connection and the number of pins, which could be used as the design basis of the beam-column joints with metal connectors. The cracking of the wood after pin yielding occurred. The initial cracking depended on the shear strength or perpendicular tension strength of the wood and the pin hole position at the end of beam. After the initial cracking, the dowel could still play a supporting role, which kept the joint a good ductility. The standard percentile values of bearing capacity of sawn timber and glulam beam by test data had a good correspondence with the calculated value of the yield load formula specified in the several standards. The calculation formulas of brittle failure in the standards from various countries could predict the brittle failure of the pin connection. Compared with the testing values, the calculation values of the cleavage failure in the Japanese standard were closer, and the calculation results of the European and Canadian standards were more conservative. The brittle failure in the design of the wood connection in our current standard had not been considered fully. In the future, further research should be done related to the calculation formula and parameters of the dowel connection to better ensure the safety and reliability of the wood components connection.

Objective: By evaluating the effects of VOCs released from MDF on indoor air quality(IAQ), the maximum loading capacity of MDF when it was used alone indoors was estimated. Method: Unfinished MDF, PVC facing MDF and melamine finishing MDF were selected as research objectives, the 1 m³ climate chamber was used to simulate indoor environment and GC-MS were used to analyze VOCs concentration changes of MDF during one cycle. The main pollutants released by MDF were determined through establishing single factor index model, and the improved Shen model was used to make a comprehensive evaluation of possible pollution caused by MDF to the indoor environment. Result: The results showed that when the indoor environment was under the test conditions of this climate chamber, the main pollutants released by unfinished MDF were esters, aromatic hydrocarbons and olefins. The main pollutants released by PVC facing MDF and melamine finishing MDF were both aromatic hydrocarbons and esters. After the release of VOCs reached an equilibrium state, when melamine finishing MDF was used alone indoors, the indoor air quality was grade Ⅰ, being suitable for living. In the initial stage of release, when unfinished MDF or PVC facing MDF were used alone indoors, the indoor air quality were grade Ⅴ and grade Ⅳ, which were seriously polluted. After the release of VOCs became stable, the indoor air quality was all grade Ⅱ, which met the living conditions. Under the premise of ensuring that the indoor air is not polluted, the maximum loading capacity of control MDF, PVC facing MDF and melamine finishing MDF were 1.5, 1.8 and 3.2 m²·m^-3, respectively. Conclusion: The evaluation of the impact of volatile organic compounds released from MDF used on indoor air quality was quite satisfactory. After the release of volatile organic compounds achieved a steady state, the indoor air quality where the MDF was used alone, achieved a pollution-free standard. Under the premise of guaranteeing that the indoor air is not polluted, the maximum loading capacity of control MDF, PVC facing MDF and melamine finishing MDF were 1.5, 1.8 and 3.2 m²·m^-3, respectively.

Most PSESP (Plant Species with Extremely Small Populations) in China are endemic species, and contribute greatly to the maintenance of species diversity in China. As one of the endemic species in Zhejiang Province, Ostrya rehderiana has only 5 naturally-regenerated mature individuals that occur in the same region. The reveal of its mechanism of endangerment is an important basis for the protection and restoration of the population. We reviewed the studies on potential endangerment mechanism of O. rehderiana and classified them into two categories: the external factors like climate change, human disturbance and pest damage, as well as the internal factors such as photosynthetic capacity, growth rhythm, seed vigor and genetic diversity. 1) External factors: Climate change since Quaternary Glaciations led to a sharp decrease in the number of the effective population of O. rehderiana; man-made disturbance made O. rehderiana greater survival pressure and smaller population size; damage from diseases and insects also affected the survival rate of seedlings. 2) Internal factors: The narrow range of light adaptation and low photosynthetic rate of O. rehderiana made it inferior in the competition for light resources in the community, which impaired its environmental adaptability. The features of growth rhythm, such as short pollination time, low pollen germination rate and short life span, resulted in low seed yield and poor quality. The seed structure and the restrictions of endogenous nutrients and phytohormones led to the low seed germination rate and very few naturally-regenerated seedlings. The extremely small population size and the low level genetic diversity made the inbreeding of O. rehderiana very serious, which led to decreased heterozygosity, bringing about the weaker heritability, fertility, vitality and adaptability in offspring. In summary, human disturbance and climate change should be the direct reasons for the sharp decrease of the population size. The frequent inbreeding and lower genetic diversity might have led to potential defects in development and reproduction. In addition, due to the competition for resources with other populations in the community, it might be too difficult for O. rehderiana seedlings to naturally regenerate, which also makes the recovery of its population size improbably. However, the past protection of O. rehderiana, one of the PSESP with very low level genetic diversity, only focused on the removal or control of endangered factors, but not its unique genetic problems. Therefore, in order to protect O. rehderiana effectively, multiple method should be used, such as designing artificial hybridization strategy, together with vegetative propagation, increasing fertility of wild individuals, sustaining genetic diversity in the limited gene pool, combined with in-situ conservation, ex-situ conservation and reintroduction to the wild, the species of O. rehderiana might be finally protected and recovered.

The mechanisms of tree mortality caused by forest fire are of great guiding significance to forestry practices such as prescribed burning, fire loss assessment and restoration of burned area. However, the action way of forest fire on trees and the factors affecting tree mortality are still unclear. In this review, the forest fire behavior is associated with the burn of tree crown, bole, and roots, and whole-tree mortality. The biological mechanisms underlying fire-caused tree mortality and influencing factors are analyzed. Finally, the review summarizs the method of assessing fire injury and prediction models of tree mortality. It can be seen from the literature review that the direct mortality of trees after fire depends on the burn of leaves and meristem(bud and cambium). The boundary conditions during tissue heating and metric of localized heat-transfer are vital variables in determining and predicting fire-caused tree mortality. Carbon starvation caused by the reduction of canopy photosynthesis and phloem transport and water stress induced by cavitation and deformation of xylem contribute to tree mortality following fire. Compared to carbon starvation, the impact of hydraulic failure on post-fire tree mortality is greater in short term. The response of leaves during fire depends on stomatal conductance and stomatal sensitivity to an increase of vapor pressure deficit, and photosynthesis rate per unit area will increase temporarily due to increasing mineral nutrient after burning. In addition, the variations of secondary metabolites such as phytohormone, phenol, terpene and alcohol, which are correlated with insect attacks, can reflect physiological responses in delayed mortality. Crown scorch variables following fire are reliable to evaluate tree survival and growth condition within short-term. Leaf flushing in the second year following fire can be used as a supplementary standard. For now, independent indicator variables, comprehensive rating indexes and statistical empirical models are the most simple and effective method to predict tree mortality, while biophysical model based on process is further research trend in the future. In addition, this paper also summarizes existing problems in the field, andproposes the corresponding opinions and suggestions in future study related to post-fire tree mortality.

Objective: Measuring forestry and its three industries' contributions to ecological civilization, and comparing the other industries' contributions with forestry's contribution are favorable for managers to grasp the objective regulations those forestry has on ecological civilization, which can also support some references for managers to scientifically put forward some differentiation strategies of developing industries to stimulate the construction of ecological civilization better. Method: With the data of ten years from 2007 to 2016, firstly, the indicators of ecological civilization were optimized and their weightings were also determined with the method of PSIR-SEM according to these indicators. Secondly, by means of the coupling from indicators to indexes of Lotka-Volterra symbiotic model, threshold values and green degrees were calculated to respectively judge "stage and level" for ecological civilization in order based on the indicators and their weightings. Thirdly, the level of ecological civilization was put as the dependent variable and the levels of agriculture, forestry and its three industries, graziery, fishery, industrial, construction, transportation, science and technology, ecological environmental protection were put as the independent variables, the regression model was then built to estimate the coefficients of forestry and its three industries to ecological civilization. Finally, the contribution rates of forestry and its three industries to ecological civilization were calculated on basis of coefficients. Result: 1) The contribution rate of forestry to ecological civilization was positive and the largest, while the contribution rate of industry to ecological civilization was negative. The contribution rate of forestry, agriculture, ecological treat, science and technology, industry, construction, transportation, graziery and fishery to ecological civilization was decreasing successively. 2)The contribution rates of forestry three industries to ecological civilization from large to small were forestry primary industry (positive), forestry tertiary industry(positive)and forestry secondary industry(negative). Conclusion: The contribution rates of industries to ecological civilization depend on ecological benefits property of industries. The contribution rates of forestry three industries to ecological civilization present the feature of a "structure smiling curve".

Objective: The impacts of varying N fertilization patternser modes and rates quantities were incorporated to the soil to assessed their influence on biomass and root morphological traits of one-year-old Fokienia hodginsii seedlings. The current study was aimed to provide a theoretical basis for the rational application of N fertilizer in F. hodginsii seedlings plantation. Method: One-year-old F. hodginsii seedlings were grown under three treatments: average fertilization (applying the same amount of N with the same interval), exponential fertilization (adding N according to the N index), and the control (CK). Effects of different N application quantities on allocation of leaves, stem, and roots of the seedlings were also determined and Lorentz model and parabolic model were used to fit the relationship between root biomass, height and diameter. Moreover, the optimum pattern and quantity of N application were evaluated using principal component analysis. Result: The application of N (average fertilization and exponential fertilization) had a significant effect on the seedling biomass of F. hodginsii. The influence of the two models of nitrogen application on biomass allocation was different. However, the biomass of roots, stems, and leaves showed the same trend of increasing followed by decreasing with the increase of nitrogen application. The biomass of roots and stems amended with exponential fertilization was higher than that of the average fertilization. Seedlings treated with N fertilizers showed improved root morphological traits (total root length, total root surface area, total root volume, average root diameter, and specific root length) compared to the CK. The trend of root morphological changes was consistent with biomass allocation with an increase of N application, and the root indices of the treatment of average fertilization were higher than that of the exponential fertilization treatment. The Parabolic model as a multi-variable nonlinear model showed a better fit to the total root biomass with higher correlation coefficients (R² is 0.922-0.978) and the smaller residual sum of squares RSS (0.234-0.841). The fitting was better than that of the Lorentzian model, which can accurately predict the root biomass and height and diameter under different nitrogen treatments. Conclusion: The two application patterns had positive effects on the biomass accumulation (above and below ground biomass) and growth attributes of F. hodginsii but the exponential fertilization showed better results than the average fertilization and 600 mg per plant proved to be the best N application.

Objective: To explore the anatomical characteristics of fine roots of trees under drought environments, and to reveal the ecological strategies of trees adapted to drought stress. Method: Fine roots were sampled from eleven tree species in a 4 hm² plot which was established in 2011 in the hilly mountainous areas in central parts of Shandong province. Anatomical structures (root diameter, cortex thickness, vascular cylinder (stele) diameter, vessel inner diameter, and the density of vessels) of 2 475 samples of roots from the first to the third order were measured via microscopy imaging system and paraffin sectioning. One-way ANOVA was conducted to compare differences in the anatomical characteristics among the tree species, and Principle Component Analysis (PCA) was performed to group the tree species. Result: The diameter of fine roots of the 11 tree species increased with root orders in general. The diameter, cortex thickness, vascular cylinder (stele) diameter of the fine roots within the same root order was significantly different among species (P < 0.05). Gleditsia sinensis has the largest cortex thickness of the first and the second order roots whereas Clerodendrum trichotomum and Morus alba have the smallest. Cotinus coggygria has the largest stele diameter in the third order roots; Melia azedarach has the largest vessel inner diameter. Pistacia chinensis has the smallest stele diameter and vessel inner diameter; P. chinensis has the largest root vessel density. PCA analysis showed that the first component explained 46% of variation in fine root anatomical traits representing absorptive functions, and the second component summarized 38% of variation in fine root anatomical traits responsible for transportation. PCA analysis grouped the 11 tree species into three groups based on anatomical features of fine roots, with the first group possessing a smaller root diameter, thinner cortex and more compacted transportation tissues (including 8 tree species such as M. alba, P. chinensis), the second having a smaller root diameter and thinner cortex, but looser transportation tissue (including C. coggygria and M. azedarach), and the third group showing a larger root diameter, thicker cortex and more compacted transport tissue (only including G. sinensis). Conclusion: Anatomical structure of fine roots reflected their adaptation to arid habitats. The eleven species displayed two strategies to adapt to the drought conditions: one was fast uptake and rapid transportation of water, and another was efficient finding and rapid transportation of water. The two strategies have their own advantages in different soil conditions. Nine tree species showed their adaptation to drought via improving water absorptive capabilities. Some trees with fast water uptaking and rapid transportation, such as M. alba and P. chinensis, demonstrating more suitability for habitats with long-term drought, seasonal rainfall and thin soil layer. Some species with efficient water finding and rapid water transport, such as G. sinensis, are more suitable for the habitats with long-term drought and thick soil layer. The anatomical traits of fine roots determine the strategies of trees adapted to drought environment. The root cortex thickness and vessel properties in fine roots are important indicators of assessing the capability of trees adapting to dry soils, this would provide a theoretical basis for species selection for afforestation in arid infertile mountainous areas.

Objective: To explore the mechanism of leaf color variation of six bamboo species, we investigated the relationship among leaf color, chlorophyll and carotenoids, and cell ultrastructure in different color stripe of six colorful bamboo species. Method: We collected leaves from six bamboo species. In this study, 6 colorful bamboo species were targeted, and they are Indosasa hispida 'Rainbow' (IH), Pleioblastus fortunei (PF), Sasaella glabra f. albostriata (SG), S. kogasenis 'Aureostriatus' (SK), Hibanobambusa tranquillans f. shiroshima (HT) and Sinobambusa tootsik var. luteoloalbostriata (ST). The leaves were separated into albino stripe and green stripe regions according to leaf color. The pixel value of leaf color and the contents of chlorophyll a, chlorophyll b and carotenoids in different zones of leaves were tested. Meanwhile, the microstructure of leaves in different development stages and the ultrastructure of different color zones of mature leaves were observed and analyzed. Result: There were significant differences in photosynthetic pigment content, microstructure and ultrastructure among different leaf color zones of six bamboo species. The photosynthetic pigment content in green stripe was significantly higher than that in albino stripe. The content of chlorophyll a was the highest in green stripe, and that of carotenoid was the highest in albino stripe. Microstructure of leaves at different developmental stages showed that albino stripe appeared in mature leaves for SK, while albino stripe appeared in the leaves at middle developmental stage for IH, PF, SG, HT, ST. The albino stripe of mature leaves in IH and SK showed the serious deficiency of cytoplasmic substances, while albino stripe in the other four bamboo species showed partial deficiency. The ultrastructure of the leaves of six bamboo species showed that chloroplast distributed in two types of mesophyll cells which are arm cells and rosette cell cells in green stripe. While there were a few organelles and abnormal chloroplasts in albino stripe. And the plastid morphology of six bamboo species were different. Conclusion: The appearance of white (yellow) stripes in leaves of six colorful bamboo species is not related the arrangement of cells. The appearance of yellow stripes in SK is caused by the degradation of photosynthetic pigment and the destruction of chloroplast structure after leaves matured. While the different leaves color in IH, PF, SG, HT and ST are related to the chloroplast dysplasia and low content of photosynthetic pigment in some cells. The proportion of carotenoids in albino stripe affects the yellow degree of leaves.

Objective: The aim of this study was to provide basic data reference for the selection of wood flooring and further guarantee the indoor air quality by verifying the formaldehyde release under the conditions that laminate flooring is completely paved in habitable room. Method: In this study, five batches of laminate flooring with formaldehyde emission less than 0.06 mg·m^-3(1 m³ chamber method)were selected as research objects, and according to five kinds of habitable room respectively, which formaldehyde concentration in the verification space was tested by phenol reagent spectrophotometry. Result: 1) Before paving the floor, the selected space in this study was verified the existence of a certain amount of formaldehyde (hereinafter referred to as C₀) in the air. In Ⅰ class buildings, C₀ of 1 h and 12 h in the range of 0.006-0.031 mg·m^-3 and 0.006-0.032 mg·m^-3, with a mean of 0.015 mg·m^-3 and 0.016 mg·m^-3, respectively. In class Ⅱ buildings, C₀ of 1 h and 12 h was in the range of 0.004-0.021 mg·m^-3 and 0.004-0.022 mg·m^-3, respectively, with a mean of both 0.015 mg·m^-3.2) After paving the floor, with airtight time increased in the door and window, formaldehyde concentration also increased in the air. When the airtight time increased from 1 h to 12 h, the average value of C in class Ⅰ buildings increased from 0.054 mg·m^-3 to 0.068 mg·m^-3, while In class Ⅱ buildings, the average value of C increased from 0.055 mg·m^-3 to 0.066 mg·m^-3.3) Five batches of laminate floorings were selected to be paved in five kinds of indoor spaces respectively, and formaldehyde concentration released from laminate floorings to the verification spaces at each sampling point(after deducting C₀) conformed to the national standard GB 50325—2010 and GB/T 18883—2002. Meanwhile, the formaldehyde concentration of each sampling point still conforms to the national standard. Conclusion: Accordingly, under the testing conditions, formaldehyde emission concentration of the house still meet the national building and air quality standards after paved laminate flooring completely. It is suggested to study the effects of different formaldehyde grades and flooring types on formaldehyde concentration in indoor air in the future, with aims to systematically and scientifically evaluate the relationships between the basic performances of wood flooring and formaldehyde concentration in indoor air.