Objective: In order to enhance understanding of the storage and allocation of carbon (C), nitrogen (N) and phosphorus (P) at the whole tree level, we quantified these inter-organ and inter-specific differences in C, N, and P contents and their stoichiometric relationship in the co-existing tree species, and explored the strategies of inter-organ nutrient allocation of coexisting tree species and inter-specific difference in nutrient uptake. Method: The C, N, P contents and their stoichiometry for different organs (leaf, branch, bark, sapwood, heartwood, stump, 5 mm < diameter≤ 30 mm large root, 2 mm < diameter≤ 5 mm coarse root, and diameter ≤ 2 mm fine root) were measured for 10 broadleaf tree species in a temperate mixed deciduous forest in Maoershan area, Heilongjiang Province. The coefficient of variation (CV) was used to express the differences among organs or tree species, and the slopes of standardized major axis regressions were used to test the allometric or isometric scaling relationships between elements. Result: The effects of tree species, organs and their interaction on C, N, P contents, C: N, C: P and N: P were all significant except the effect of tree species on C: P. For mean values, resource acquisition organs (leaf and fine root) had higher C, N, P contents and N: P, while the xylem (sapwood and heartwood) showed higher C: N, C: P than the other organs. For inter-specific variations, leaves had low inter-specific CVs of element contents and their stoichiometric ratios; fine roots had high inter-specific CVs of N, C: N, and N: P, but low inter-specific CVs for Pand C: P, suggesting that tree species in this area preferentially allocated the limited element N to the photosynthetic organ. For most organs, relationships between elements were not significant, indicating that the nutrient stoichiometric relationships for single organ could not directly represent the nutrient stoichiometries for other organs or at the whole tree level. The relationships between C and N or C and P across the nine organs varied with species, but the relationship between N and P was highly consistent in different species. Conclusion: The differences in C, N, P contents and their stoichiometric ratios were closely related to the functional differentiation among organs. Overall, the limited element N was preferentially allocated to leaves and constrained carbon sequestration in wood; whereas the utilization of C, N, and P for each organ diverged obviously among the coexisting species, which was likely to help reduce the inter-specific competition. No matter at the intra-specific or the inter-specific levels, the nutrients contents and their stoichiometric relationships of single organ could not directly reflect that of other organs. Therefore, only using one organ to assess the C, N, and P storage and allocation patterns at the whole tree level was inaccurate, thus future studies should fully consider the inter-organ and inter-specific differences of element contents.

Objective: To investigate the quantitative relationship between forest color landscape pattern indices (referred to as color pattern index), color attribute indicators and scenic beauty estimation (SBE); to establish an ornamental effect evaluation model; to screen for key indicators affecting SBE; to provide guidance for forest color landscape pattern allocation. Method: Typical mountain forest landscapes in the Yangtze River Delta region were studied, PS, Color Impact, CAD, ArcGIS, and Fragstics software tools were employed to divide color patches; calculate color pattern indices; obtain SBE via psychophysical method; generate statistics; analyze correlations between color pattern indices, color attribute indicators and SBE; establish an ornamental effect evaluation model and screen for key indicators affecting SBE. Result: The Pearson correlation analysis showed that the maximum patch relative area (r=-0.311, P < 0.05), forest color distribution model (r=-0.690, P < 0.01), and contagion index (r=-0.398, P < 0.01) were significantly (P < 0.05) or highly significantly negatively (P < 0.01) correlated with color SBE. Average patch fractional dimension (r=0.322, P < 0.05), Shannon's diversity index (r=0.352, P < 0.05), landscape abundance (r=0.655, P < 0.05), and panchromatic brightness (r=0.482, P < 0.01) were significantly and highly significantly positively correlated with color SBE. The landscape level index was more correlated with SBE than the patch level index, and the panchromatic attribute index was more correlated with SBE than the main and auxiliary color attribute indices. The correlation among the three indicators of panchromatic chromatic aberration, edge density and perimeter area ratio was highly significant (r>0.800, P < 0.01). There was a highly significant positive correlation between the relative area of the main color and contagion (r=0.862, P < 0.01), a highly significant negative correlation between the contagion and Shannon's Diversity Index (r=-0.862, P < 0.01), and a highly significant negative correlation between the relative area of the main color and Shannon's diversity index. The SBE evaluation model (R²=0.834 4) showed that forest color landscapes exhibited great ornamental effect if they tended to aggregate but did not completely connect, panchromatic relative area was large but main color relative area was small, color patches had natural curvilinear edges and perfect shape, colors were rich but displayed uneven spatial distribution, and color patches had natural and orderly mosaics with high ornamental effect. The effect of forest color distribution model indicators on SBE, which was proposed for the first time in this study, was highly significant (r=-0.690, P < 0.01), and the SBE of the color distribution model was high if the model featured favorable changes in color pattern, a high sense of order and strong naturalness. Conclusion: There are significant and highly significant correlations between SBE and color pattern index, it is feasible to apply the color pattern index for color ornamental effect evaluation using the established eveluation model.

Objective: The mechanism of forest stability maintenance based on spatial structure was discussed and the forest "random structural framework-stability" hypothesis was also put forward, to provide scientific reference for improving the stability of plantation in China. Method: Taking the typical natural forests in different climatic zones in China as the research objects, the stand spatial structure parameters of uniform angle index were used to interpret the pattern of tree points. The structural unit was defined according to the distribution form of the nearest four adjacent trees around the reference tree. The composition of typical natural forest structural unit was analyzed and the universal structure law of natural forest with high stability was revealed. Result: The trees in the natural forest are mainly composed of random trees, whose tree number frequency is as high as 55%, and the basal area accounts for more than 50%; random trees constitute the main body of natural forests, which haven't corretation with the geographical distribution and forest types of natural forests, and don't correlate with the tree species composition and pattern types of natural forests either. Conclusion: Random tree is the cornerstone of natural forest stability, and its main composition in natural forest is the key to promote forest stability. The random structural unit in the stand makes the random trees have the neighborhood microenvironment with light on both sides, compared with the regular unit, the reference tree has less competitive pressure from its neighbors. Compared with the clumped unit, the degree of extrusion between the neighbors of random trees is smaller, so the survival pressure of random trees and their neighbors (random structural unit) is relatively small, and they can obtain a greater survival probability in the process of natural succession. The more the number of random structural unit is, the more stable the forest community might be.

Objective: This study aimed to develop a generalized forest volume model with same variables and stable structure based on airborne laser scanning(ALS) data, which would provide a reference for standardizing forest volume modeling and evaluation. Method: Based on the ALS data and field measurement data of 790 sample plots distributed across the larch(Larix spp.), Korean pine(Pinus koraiensis), poplar(Populus spp.) and birch(Betula spp.) forest stands in northeastern China, the stand volume regression models were developed through multiple linear regression and nonlinear regression methods, and the generalized model with same variables and unified structure was determined by comparison and analysis. Then, the stand volume models with the same ALS variables were developed jointly for different forest types, using the dummy variable modeling approach. Result: The developed multiple linear volume regression models for the 4 stand types have 2-6 explainable variables and the coefficients of determination(R²) are 0.701-0.827; the nonlinear models have 2-4 explainable variables and the R² are 0.707-0.818. The R² of two-variable nonlinear volume models based on mean height and mean intensity of point clouds are 0.679, 0.814, 0.698 and 0.703 for larch, Korean pine, poplar and birth forest stands, respectively; the mean prediction errors(MPEs) are 4.26%, 2.90%, 3.68% and 3.83%, and the mean percent standard errors(MPSEs) are 24.44%, 18.23%, 21.47% and 23.26%, respectively. Conclusion: For estimating stand volume based on ALS data, the nonlinear model might be better than the linear model, and the two-variable model based on mean height and mean intensity of point clouds might be generally applicable, which could be defined as standard model for estimating stand volume. The stand volume models developed in this study for 4 forest types using dummy variable modeling approach could meet the need of precision requirements to relevant regulations on forest resource inventory, indicating that the models could be applied in practice.

Objective: This paper aims to study the effect of exogenous regulators on physiological characteristics and stress resistance of Erythrophleum fordii subjected to lead stress, and to explore the response mechanism of the plant to lead ions, so as to provide theoretical guidance for the cultivation, and introduction of and its function in restoring heavy metal contaminated soil. Method: In this study, one-year-old seedlings of E. fordii were treated with different concentrations of betaine (BT), salicylic acid (SA), methyle jasmonate(MeJA) and calciumchloride(CaCl₂), and then the seedlings were subjected to lead stress(10 mmol·L^-1). The activity of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)), contents osmotic adjustment substances, leaf cell membrane permeability and chlorophyll content (SPAD value) in E. fordii seedlings were measured. Result: The results showed that lead stress significantly inhibited the growth of seedlings, resulting in a significant decrease in the content of osmotic adjustment substances, a significant increase in MDA content and RC, and inhibition of photosynthetic pigment synthesis. Compared with the non-stress control(CK1), the activities of SOD, POD and CAT increased by 7.0%, 1 221.6% and 121.0%, respectively. The results showed hat E. fordii seedlings had a certain resistance to lead stress. The exogenous regulators had significant effects on activating antioxidant enzymes activities, increasing PRO and SP content, reducing MDA content and RC, and promoting the synthesis of chlorophyll, but had no promotion effect on SS content. Compared with the treatments of lead stress (CK2), MeJA of 0.1 mmol·L^-1 increased SOD activity by 13.2%, BT of 100 mg·L^-1 enhanced CAT activity by 17.7%, SA of 25 mg·L^-1 improved POD activity by 36.2%, MeJA of 1 mmol·L^-1 improved PRO content by 157.3%, BT of 1 000 mg·L^-1 increased SP content by 71.9%, CaCl₂ of 5 mmol·L^-1 enhanced SPAD value by 22.9%, BT of 100 mg·L^-1 decreased MDA content by 58.9%, and BT reduced the RC to some extent. Correlation analysis showed that there was a direct or indirect internal correlation between those physiological indicators. Physiological indicators promoted or antagonized each other, and regulated dynamic repair of damage by lead stress. Conclusion: Exogenous regulators can effectively alleviate the damage of lead to E. fordii seedlings. According to its overall benefit contribution, the performance of exogenous regulators in adaptively inducting lead resistance is 1 mmol·L^-1 MeJA > 20 mmol·L^-1 CaCl₂ > 100 mg·L^-1 BT > 5 mmol·L^-1 CaCl₂ > 0.1 mmol·L^-1 MeJA > 500 mg·L^-1 BT > CK2.

Objective: In this study, the influence of temperature and light on leaf coloration of three cultivars of Buxus mircophylla during overwintering was studied. The threshold value of the temperature and light on B. mircophylla leaf reddening in winter was explored. This study aims to provide a theoretical basis for the application of evergreen broad-leaved plants in witer and the promotion of green landscape in northern China. Method: From 2011 to 2013, the temperature of the three cultivars of B. mircophylla and the illumination conditions of the leaves under five different shading treatments were monitored in two consecutive overwintering and regreening periods (from October of the first year to March of the following year). Meanwhile, the redness index and anatomical structure of leaves were observed dynamically during the periods. Correlation analysis and linear fitting were used to investigate the relationship between the temperature, light and the leaf coloration of the Buxus mircophylla during overwintering. Result: The three cultivars appeared different leaf coloration in winter, among which 'Greenbeauty' maintained the best greening effect, 'Sunnyside' performed a moderate redness in winter but retruned green the latest in spring, and 'Wintergreen' turned red seriously in winter but returned green the earliest in spring. The reddening of the wintering leaves of the three cultivars was directly related to temperature changes, and the critical temperature for the leaf reddening on the adaxial side was lower than that on the abaxial side. Among them, the critical temperature for leaf redness of 'Greenbeauty' was the lowest (0.67-1.55 ℃ on the adaxial side and 5.25-7.68 ℃ on the abaxial side), different performances were presented on the adaxial and abaxial sides of 'Sunnyside' and 'Wintergreen'. Among them, the critical temperature of 'Sunnyside' leaves was 4.33-6.42 ℃ on the adaxial side and 8.43-9.41 ℃ on the abaxial side; the critical temperature of 'Wintergreen' leaves was 4.16-4.98 ℃ on the adaxial side and 9.41-10.23 ℃ on the abaxial side. The red index (RI) of the leaves of the three cultivars decreased with the light intensity. Conclusion: The leaf reddening of the three cultivars of B. mircophylla is closely related to the interaction between low temperature and relatively high light during the overwintering. The sunny leaves of three cultivars show differences in leaf coloration, reflecting their different tolerance to low temperature + high light and the sensitivity of the leaves. These results suggest that B. mircophylla should be planted under a sheltered environment which is conducive to maintaining a good green landscape in winter.

Objective: This study exploredthe effect of different canopy heights of broad-leaved trees on the relationship between individual leaf mass and leafing intensity of current-year twigs, which is helpful to understand the impact of light environment changes on the twig traits. The main objective of this paper is to provide a theoretical basis for revealing the response mechanism of broad-leaved trees canopy growth to the changes in light environment. Method: In this study, the standardized major axis estimation method was used to determine the allometric growth relationship (the relative growth of a certain part of the tree itself) between individual leaf mass(ILM) and leafing intensity (leafing intensity per unit stem mass or leafing intensity per unit stem volume, Lim and Liv) at the different canopy heights of 69 broad-leaved tree species in Yangjifeng Nature Reserve, Jiangxi Province. The effects of canopy heights (upper canopy height and lower canopy height) on individual leaf mass and leafing intensity relationship of evergreen and deciduous trees in subtropical evergreen broad-leaved forests were analyzed. Result: 1) There were significant differences in Liv, specific leaf area and individual leaf area between evergreen and deciduous trees (P < 0.05), but no significant differences in leaf number, ILM, Lim and stem density (P>0.05). There was significant difference in leaf number, Liv, specific leaf area, Lim and stem density of evergreen tree species at different canopy heights (P < 0.05).However, there were only significant differences in leaf area among deciduous trees at different canopy heights (P < 0.05). 2) The relationship between individual leaf mass and leafing intensity of the current-year twigs was negative isometric among evergreen and deciduous trees at different canopy heights. The canopy height had no significant effect on the allometric growth index (equation slope) of ILM-Lim in evergreen trees (P=0.95), but the allometric growth constant (equation intercept) of the upper canopy ILM-Lim was significantly higher than that of the lower canopy (1.24, 1.05, respectively); The canopy height had no significant effect on the allometric growth index (P=0.65) and allometric growth constant (P=0.83) of the deciduous trees ILM-Lim. 3) The canopy height had no significant effect on the allometric growth index (P=0.43) and constant (P=0.16) of the current twigs ILM-Liv of evergreen trees. The canopy height had no significant effect on the allometric growth index (P=0.69) and constant (P=0.28) of the current twigs ILM-Liv of deciduous trees. Conclusion: The canopy height has no effect on the negative isometric relationships between individual leaf mass and leafing intensity of current-year twigs of evergreen and deciduous trees. However, the canopy height hasa significant effect on the allometric growth constant of evergreen trees. The result indicates that under a certain leafing intensity, the upper canopy has higher individual leaf mass. This may be due to the relationship of resource acquisition strategies between twigs and leaf at different canopy heights.

Objective: Accurate species definition is the premise for development and utilization of wild plant resources. Due to the fact that chloroplast DNA fragments cannot distinguish Rhododendron species of the Baili Rhododendron Reserve in Guizhou reported before, the present study attempted to explore the phylogenetic relationships of Rhododendron in this region based on genome-level RAD(restriction-site associated DNA) sequencing technology, aiming to detect the power of RAD for species definition of complicated plant groups. Method: RAD-seq sequencing was performed on 34 species of Rhododendron from the reserve, and the basic characteristics of the data such as depth, coverage and polymorphic sites were evaluated. De novo method was employed to call SNPs which were subsequently evaluated to be neutral or selective by Tajima's D. Based on these neutral SNPs, fastStructure, PCA, GCTA and IQ-Tree software were finally employed to perform genetic separation, clustering and phylogenetic tree construction. Result: A total of 42 083 SNPs were obtained, among which 28 983 SNPs were detected to be neutral. The analyses of PCA, fastStructure and phylogenetic tree supports the morphological classification of 34 species of Rhododendron at the subgenus level. Subgen. Hymenanthes, Subgen. Azaleastrum, Subgen. Pentanthera and Subgen. Tsutsusi of the 6 subgenera can be distinguished, whereas Subgen. Pseudorhodorastrum and Subgen. Rhododendron cannot, suggesting that the 2 subgenera are closely related. In addition, at species-level most species can be distinguished, indicating a great improvement compared to previous studies, but the species with very similar morphological characteristics are indistinguishable, such as R. floribundum and R. denudatum. Conclusion: RAD-seq data produced a large number of SNPs that can distinguish most Rhododendron species in the reserve at the subgenus and species levels, proving that RAD technology had significant advantages over traditional molecular markers in the classification of complicated plant groups.

Objective: Optimization of an in vitro germination protocol to effectively determine the viability of Paeonia ludlowii pollen, the effects of different storage conditions and incubation temperature on pollen longevity were compared to determine the appropriate temperature for pollen storage in the short, mid and long term, and the physiological mechanism of the programmed death of P. ludlowii pollen at different storage temperatures was analyzed, so as to provide a basis for cross breeding and germplasm resource conservation. Method: The fresh pollen of P. ludlowii from Tibet was used to examine pollen morphology by scanning electronic microscope (SEM). Pollen germination was characterized by in vitro culture to investigate the effects of different storage temperatures and times on pollen viability and activity of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT), as well as the contents of ascorbic acid(AsA) and malondialdehyde(MDA). Result: The rate of pollen plumpness of P. ludlowii is high under the natural conditions, and the deformity rate is only 5.6%, and the sexual reproductivity is relatively high. The factors influencing the pollen germination were as follows: sucrose > boric acid > CaCl₂ > GA₃. The longevity of pollen stored at room temperature was only 24 days, the longevity of pollen stored at 4 ℃ was about 80 days, and the longevity of pollen stored at -20 ℃ was 120-184 days. The pollen longevity for storage at -80 ℃ was over one year, and the suitable temperature for long-term preservation of pollen was at -196 ℃. The germination rate of pollen decreased rapidly before and after the drastic changes of pollen protective enzyme, MDA content and AsA content. SOD, CAT, POD activities and AsA content at -196 ℃ remained stable and the ability of eliminating active oxidation was strong. Correlation analysis showed that SOD activity was the most important physiological factor that affected the pollen longevity during storage, and membrane peroxidation was the main physiological factor that caused pollen death. The three protective enzymes and AsA under different storage temperatures had different effects: POD served as a sensitive protective enzyme at room temperature, SOD served as a sensitive protective enzyme at - 20 ℃ and - 80 ℃, whereas both SOD and CAT served as sensitive protective enzymes at 4 ℃. The order of the effects of three protective enzyme activities and AsA content on pollen germination rate was as follows: SOD > CAT > AsA > POD. Conclusion: The rate of pollen plumpness was correlated with the germination rate. The highest germination rate in Paeonia ludlowii was about 92.10% of the pollen treated with 120 g·L^-1 sucrose+45 mg·L^-1 boric acid + 55 mg·L^-1 GA₃ + 30 mg·L^-1 CaCl₂. The room temperature was suitable for the short-term storage of P. ludlowii pollen within 24 days, 4 ℃, -20 ℃ were suitable for the mid-term storage of pollen in 80-120 days. -80 ℃ was suitable for transannual storage of pollen, and -196 ℃ was suitable for long-term storage of pollen. The generation and removal of reactive oxygen species within pollen cells were at an equilibrium when the pollen was stored at -196 ℃, and the stability of cell membrane system was the physiological responses to keeping high pollen germination rate. The cell membrane peroxidation and damage caused by excessive accumulation of reactive oxygen species and free radicals were the main reasons for the decrease of pollen germination rate after storage at room temperature, 4 ℃, -20 ℃ and -80 ℃.

Objective: Gravity plays an important role in growth and development, in terms of morphogenesis, physiology, metabolism and other biological process in plant. The change of gravity condition will induce a series of changes in plant growth and orientation. In response to the change of gravity conditions, the activities of cambium in woody plant increase unevenly, leading to the eccentric growth of stem and the formation of reaction wood with the obvious changes of xylem structure and cell wall components. Monocotyledons have no cambium, and the stem node elongated through the activity of intermediate meristem. In order to explore the response process and structural changes of monocotyledons under gravistimulation, we use maize to analyze its dynamic process and morphological changes in response to gravistimulation. By comparing with xylophyta, the differences of gravity response between monocotyledons and xylophyta were revealed. It provides a basis for further studies on the gravity response of monocotyledonous woody plants (such as bamboo, etc.) and other trees. Method: The inbred line B73 of maize was used to grow seedlings until 10 leaf stage, the seedlings were laid down horizontally, and the seedlings used as control were still kept upright. The dynamic changes and time points of maize gravity response process were recorded by delay photography. Through tissue sections and special staining, the changes of tissue structure and the differences of cell wall components in maize stem nodes response to gravity were analyzed. Result: The node which the first flag leaf came from was counted as the first one, then the stem nodes were numbered from the bottom to the top. Following the gravity induction, the response processes changed as followed: 1) Gravity response process: Maize plants sense the gravity from the top down subsequently. The plants began to respond to gravity 10 hours after induction. In the next 20 hours, the plants were bent up from the top to the fourth stem node successively, until the plant was perpendicular to ground that is the termination state. 2) Morphology and structure: The repeated experiments showed that only the fourth, fifth and sixth stem nodes had morphological changes, where different degrees of tissue expansion occurred at the side facing ground. The tissue growth and internal vascular bundles in expanded parts of these three stem nodes showed upward bending. The corresponding stem nodes of the control plants showed normal morphology. 3) Vascular bundles: Compared with the control group, the number of proximal vascular bundle cells increased and showed spindle shape, and the cell wall became significantly thinner without obvious vessel tissue, while the number of cells and the thickness of cell wall in the distal vascular bundles varied with the developmental status. In addition, the fourth internode changed most significantly. 4) Cell wall components of vascular bundles: The sections of normal and experimental stem were stained with phloroglucinol and Calcofluor white respectively. The results showed that the content of lignin in the cell walls of proximal vascular bundles was low, and the content of cellulose was higher than that of the control. There was no significant content change in the cell wall of the distal vascular bundles compared with the control. Conclusion: In response to gravity condition, maize can adjust the extension direction of stem node quickly, and cell number of the proximal vascular bundles increased dramatically. At the same time, the cell walls of the proximal vascular bundles became thinner with the content of lignin decreased but cellulose increased. Therefore, it is speculated that after responding to gravity, maize may produce tissues similar to tension wood and compressed wood by adjusting the activities of the intercalary meristem, but different from them. This study lays a foundation for the study of the regulation mechanism of vascular tissue development (wood formation) of woody plants in gravity response.

Objective: The chemical compositions of extracts, anatomical characteristics and plant morphology were compared between Dalbergia odorifera and D. tonkinensis, and the distinguishability of them was explored to provide a basis to determine whether they were the same species. Method: Observation method was used to observe the tree morphological characteristics of D. odorifera and D. tonkinensis. Wood anatomical method was used to observe the three dimensional sections of wood, wood tissue structure of D. odorifera and D. tonkinensis were observed by means of macroscopic and microscopic perspectives. The chemical compositions of extracts of D. odorifera and D. tonkinensis were checked by GC/MS and UPLC-ESI-MS/MS method and a comparative analysis was made. Result: The flowers, fruits, and leaves of D. odorifera were similar to those of D. tonkinensis. Compared with D. tonkinensis, the grain of D. odorifera was slightly rich. The pore type belonged to the semi-ring porous wood and the heartwood had slightly less heterogeneous-Ⅲ ray tissue, but these differences were difficult to quantify. Thus, it was difficult to distinguish between the two species and other structural features were not distinguishable. The wood from the same latitude was clustered into one group by cluster analysis and the chemical compositions of the extracts from them had no relation with species. Similarly, the PCA analysis showed no distinguishability because of obvious intersection between the two groups. Conclusion: There are no significant differences in the morphological characteristics of flowers, fruits and leaves, the anatomical structure of wood and the chemical compositions of extracts from D. odorifera and D. tonkinensis. Therefore, there was no distinguishability between the two species.

Objective: The objective of this study is to qualify the effect of root architecture and mechanical traits on root soil reinforcement, and further understand the mechanism of the root-soil interactions and soil consolidation. Method: The tensile strength, Young's modulus, friction and other mechanical characteristics of root system of Symplocos setchuensis were measured with a modified universal testing machine. Furthermore, the shear strength of root soil samples was measured by self-made large box direct shear device, in order to find out the multiple relationships between root architecture, mechanical, and soil reinforcement traits. Result: Firstly, there was a power function relationship between the root diameter of S. setchuensis with root length, tensile strength, Young's modulus, as well as pullout force. Among them, the root diameter was negatively correlated with root tensile strength, and Young's modulus, while the root diameter was positively related to root length and pullout force. Secondly, there was a strong positive relationship between root branching and pullout force. However, there was no significant statistical difference between the branching and pullout force per unit root length (or diameter). Thirdly, The increase of root branching nodes was able to significantly improve the soil reinforcement effect of root system, and each branching node could increase the additional shear strength of root system by about 50%. Moreover, the branching nodes also could increase the reinforcement effect per unit length and root diameter. Fourthly, Principal component analysis showed that root length was found strongly correlated with root reinforcement at the maximum point while diameter was strongly correlated with root reinforcement at yield point. Conclusion: The study quantified the positive influence of S. setchuensis root mechanical properties and branches on its resistance of pullout and soil shear behavior. This information is important to improve the accuracy of root reinforcement estimated and our understanding of root reinforcement mechanism.

Objective: This study aims to explore the niche and interspecific association of dominant species of protozoa community under different hydrologic periods in the Mitika Wetland National Nature Reserve of Tibet, China, to reveal the resource utilization status, functional status and ecological adaptability of the dominant species of protozoa community in different hydrologic periods, and to provide basis for further study on the stability and spatial distribution pattern of protozoan community in Mitika Wetland. Method: According to the characteristics of ecological environment, functional zoning and gradient structure of Mitika wetland, 14 representative sampling sites were set for sample collection. A total of 168 water samples were collected using 25 # standard plankton net in July (wet season) and October (dry season), 2018. The niche and interspecific association among the dominant species were analyzed via the niche breadth, niche overlap, ecological response rate, overall interspecific connections, χ²-test, association coefficient (AC), percentage co-occurrence (PC) and percentage point correlation (φ). Result: 1) A total of 141 species of protozoa were identified in wet season of Mitika wetland and 138 species were identified in dry season. Among them, there are 9 dominant species, belonging to 2 phyla and 5 genera. Cryptomonas obovate and Difflugia globulosa were the dominant species in two hydrological periods. The frequency, abundance and dominance of dominant species were different in different hydrological periods. 2) The dominant species of protozoa in the Mitika wetland are composed of broad niche species, medium niche species and narrow niche species, and the broad niche species were dominant. The result showed that there were significant differences in niche overlap values between species. The maximum and minimum values were 1 and 0.001, respectively. Moreover, the degree of niche overlap was not high, and the inter specific competition was weak; the sum of ecological response rates in the two hydrological periods was positive, indicating that the protozoan community was in the development stage. 3) The dominant species in the two hydrological periods of Mitika wetland were in general positively correlated with each other, however, the correlation among the most species was not significant (χ² > 3.841), and the interspecific relationship was relatively loose. Conclusion: Among the dominant species of protozoa community in the Mitika wetland, Bodo sp. in wet season, Cryptomonas rostrata in dry season and Difflugia globulosa in the two hydrological periods have strong adaptability to the environment, and have a wide range of ecological adaptation; while Hyalosphenia minuta in wet season and Vorticella campanula in dry season are more sensitive to the changes of water environment conditions, and their adaptability is weak. The niche overlap and breadth characteristics of some dominant species are not consistent. For example, the overlap value of Cryptomonas pyrenoidifera and Cryptomonas rostrata in dry season was high, but the niche breadth was small. The species composition and dominant species structure of protozoa community in the Mitika wetland are relatively stable and have a positive succession trend, but the relative dynamic balance between dominant species and between dominant species and environment is not reached, and the protozoa community is still in the development stage and has not yet reached the top stage of succession.

Objective: The aim of this paper is to provide scientific reference on fuel management by analyzing the effect of the fuel treatments on fire behavior of the main forest types in Daxing'anling. Method: In this study, three 20 m×20 m plots were set in each forest type during fire season of 2019, and four 10 m×10 m sub-plots were further divided in each plot. The forest types included natural forests of Larix gmelinii (Larch natural forest), Betula platyphylla (Birch natural forest), and coniferous and broad-leaf mixed forest (Larch and birch natural mixed forest), and plantations of L. gmelinii (Larch plantation) and Pinus sylvestris var. mongolica (Mongolian Scots pine plantation). The forest structure of each plot was investigated, and then four sub-plots were treated with combustible materials, including cutting dead shrubs and herbs, clearing dead branches and surface litter. The combustible materials in sub-plot were treated with four intensities (untreated, low, mid, and high intensive treatment) respectively. After low intensity treatment, there were no inflammable and dead shrubs and grass in the forest and large combustible materials on the surface (> 10 h). After medium intensity treatment, all fallen trees, shrubs and small trees were removed. After high intensity treatment, the combustible materials on the surface would not support the continuous combustion and spreading of fire. The Fuel Characteristic Classification System (FCCS) was used to simulate fire behaviors for each plot under the ordinary weather scenario and drought scenario. Result: The simulation results showed that the surface fire spread decreased by 51.6% and 42.8% for Larch natural forest and plantation under the ordinary weather scenario after fuel treatments in low intensity, respectively. The flame length dropped by 33.6% and 39.4%, and the fire intensity decreased by 33.6% and 39.4%. However, the surface fire behavior did not change significantly after the low intensity treatment in larch and birch natural mixed forest, birch natural forest, and Mongolian Scots pine plantation. The surface fire spread rate decreased by 29.4%, 37.1%, 79.1%, 83.3%, and 19.7% after mid intensity treatment in mixed forest, birch forest, larch natural forest, larch plantation, and Mongolian Scots pine plantation, respectively, and flame length decreased by 33.3%, 29.8%, 67.2%, 69.7% and 38.1%. The surface fire spread rate decreased by 95.3%, 97.6%, 85.7%, 88.9%, and 77.6% after high intensity treatment in larch natural forest, larch plantation, larch and birch natural mixed forest, birch natural forest, and Mongolian Scots pine plantation, and flame length dropped by 93.1%, 93.9%, 92.6%, 87.6%, and 87.3%, respectively. The surface fire behavior under the drought scenario in all forest types decreased significantly with the increasing intensity of fuel treatment (P < 0.01). The crown fire behavior under the drought scenario decreased significantly after fuel treatments for larch natural forest and plantation, larch and birch natural mixed forest, and Mongolian Scots pine plantation (P < 0.01). Conclusion: The surface fire spread rate is less than 1 m·min^-1, and flame length below 1 m under ordinary weather scenario after mid-intensity treatment in mixed forest, birch forest, larch natural forest, and Mongolian Scots pine plantation. The surface fire spread rate and flame length are less than 0.1 m·min^-1 and 0.1 m in larch plantation, respectively. Those fires can be suppressed directly. Crown fires may drop by more than 20% and fire spread rate decreases more than 40% under drought scenario after mid-intensity treatment in mixed forest, Mongolian Scots pine plantation, larch natural forest, and larch plantation. High intensity treatment might affect the forest structure and environment. We recommend the mid-intensity treatment on fuel management for the region.

Objective: In view of the differences in the quality of agarwood from different origins and the identification of traditional agarwood origin relying on experience judgment, high performance liquid chromatography(HPLC) fingerprint characteristics of agarwood from different origins were studied, and the feasibility of chromatographic fingerprint analysis technology for traceability of agarwood origin was also discussed. Method: 36 batches of agarwood from three origins were analyzed by optimized HPLC. The retention time and area of chromatographic peaks was obtained by the similarity evaluation system of chromatographic fingerprints of traditional Chinese medicines. HPLC fingerprints of agarwood from three different production regions were established. Principal component analysis(PCA) and orthogonal partial least squares discriminant analysis(OPLS-DA) was used to establish the discriminant methods of agarwood from different origins. Result: By analyzing the 85 characteristic peak variables of the HPLC fingerprint of agarwood from three different origins, it was found that the species and relative content of 2-(2-phenylethyl) chromone composition were the most abundant in Guan-Xiang Zone. In Sin-Chew Zone, the peaks of agarotetrol were extremely high and the relative content of the other chromones was relatively low. There were more species of 2-(2-phenylethyl) chromone in the samples of Hoi-An Zone, whose relative content was slightly lower than that in Guan-Xiang Zone and slightly higher than that in the Sin-Chew Zone. According to the geographical distribution of the origins, the samples of Hoi-An Zone showed certain transition characteristics in the three production origins. PCA analysis showed that the samples could basically be aggregated into three categories according to the origin. The accuracy of OPLS-DA analysis method in identifying the sample origin of training set and test set was 100%. Conclusion: The composition and relative content of 2-(2-phenylethyl) chromophenone in agarwood from different origins might be quite different, showing a certain extent of regional characteristics. The origin of agarwood could be identified by HPLC combined with OPLS-DA.

Objective: Potassium iodide was catalyzed by laccase and the iodine free radicals produced from the reaction could be fixed on bamboo, which was expected to improve the leaching resistance as well as the decay resistance. In this paper, enzymatic catalyzation was applied to fix antifungal agents on bamboo, which would provide an ecological and effective method for the protection and modification of wood and bamboo. Method: Using ABTS as mediator, bamboo blocks were iodized in different activities of laccase and potassium iodide(KI) combinations. The decay resistance of treated bamboo before and after 14 days was tested. The morphology and components of treated bamboo were characterized by means of scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). Result: Bamboo treated with KI alone showed limited decay resistances with a mass loss rate(ML) above 10%, while the ML of laccase catalyzed iodization of bamboo revealed better decay resistances comparing with KI alone treated ones. The best performance for bamboo protection was laccase activity at 0.60 U·mL^-1 (0.60LAK). The mass loss rate of bamboo iodized by 0.60 U·mL^-1 laccase(0.60LAK) was 7.92 % when exposed to Trametes versicolor after 3 months. After leaching, the mass loss rate increased to 9.85%, still belonged to Ⅰ decay resistance. Gloeophyllum trabeum degraded bamboo more vigorously than white rot fungi T. versicolor, causing about 24.95% mass loss rate for the untreated bamboo. The mass loss rate of 0.60 U·mL^-1 laccase iodized bamboo was 9.44%, after leaching the ML increased by 0.91%. The mass loss rate of KI alone treated one increased from 14.30% to 15.34%. Accordingly, laccase catalyzed iodination of bamboo was an effective method for bamboo against decay fungi. SEM presented clear grooves and serious damage in the structure of untreated bamboo after leaching, especially G. trabeum. Some pits were enlarged even connected together, and the integrity of cell was much destroyed. However, 0.60 U·mL^-1 laccase iodized bamboo showed a less destruction and no obvious mycelia existed. XPS analyses showed that the leached 0.60LAK samples were slightly oxidized by T. versicolor and G. trabeum. The results indicated that bamboo treated with KI-laccase could inhibit the cell wall degradation caused by T. versicolor and G. trabeum, which also had a good leaching resistance. Conclusion: The treatment of bamboo with the KI-laccase mediator systems could improve both the fixation of iodine and decay resistance, the decay resistance of laccase catalyzed iodization of bamboo was higher than that of KI alone treated. Thus, the KI-laccase mediator system might be an effective and ecological way to protect bamboo against decay fungi.

Objective: The altitudinal patterns of distribution of structural characteristics of shrub communities in the western part of Hexi Corridor was analyzed in order to explore the spatial distribution patterns of species diversity in shrub communities in desert gobi. Method: 12 plots were set up in the shrub communities within an altitudinal range of 800-3 200 m in the desert gobi to investigate the changes of species diversity along elevation. Result: From low to high altitudes, the types of shrub communities were in turn Calligonum mongolicum + Haloxylon ammodendron, Nitraria sphaerocarpa, C. mongolicum + N. sphaerocarpa, N. sphaerocarpa + Reaumuria soongarica + C. mongolicum + Ephedra przewalskii, Sympegma regelii + R. soongarica, N. sphaerocarpa + R. songarica, S. regelii + Kalidium foliatum + R. soongarica, Ajania fruticulosa + K. gracile, S. regelii, K. foliatum, K. foliatum + R. soongarica, R. soongarica, among which R.soongarica, S. regelii and N. sphaerocarpa were dominant species with large distribution range, playing an important role in the desert gobi ecosystem. The α diversity index showed a unimodal distribution pattern that increased first and then decreased along the altitudinal gradient, with the maximum value occurred at 2 000-2 200 m. The richness index (Gleason, Margalef) and the diversity index (Shannon-Wiener, Simpson) showed a significant unimodal pattern with the altitudinal gradient (P < 0.05). The vertical distribution pattern of diversity in the shrub communities in desert gobi was significantly affected by the altitudes (P < 0.05). Although the mean annual precipitation and the mean temperature were extremely significantly correlated with the altitude (P < 0.01), the correlation between species diversity and precipitation or temperature was not significant (P>0.05). The species diversity indices of desert gobi shrub communities were low, with simple structure and few species. Most Jaccard similarity levels of different shrub communities were low between altitudinal gradients. Conclusion: The distribution pattern of desert gobi shrub community was patchiness in regional scale in West Hexi Corridor. The constructive species of shrub communities changed within different altitudinal gradients. The distribution pattern of species diversity was unimodal on the altitudinal gradients, which rose first and then descend. This study will help to understand the spatial distribution pattern of shrub communities in arid region, and provide a basis for scientific conservation and management.

Objective: A novel method of obstacle avoidance path planning for a manipulator was proposed in response to meet the requirements of obstacle avoidance operations of forestry felling & cultivation machine in complex environments of forest areas. This method was expected to provide a theoretical basis for the development of forestry machinery and equipment. Method: Firstly, the kinematic analysis of the manipulator of the forestry felling & cultivation machine was carried out. At the same time, in order to solve the problems of strong random unsmooth path and long calculation time of the classic rapidly-exploring random tree, the idea of improving the artificial potential field was introduced. An avoid rapidly-exploring random tree(avoid-rapidly exploring random tree, A-RRT) algorithm was utilized for path search, which used B-spline curve fitting and the minimum inverse solution of the manipulator energy to optimize the motion path. Then the multi-point collision detection method was used, to realize the stability and rapid planning of the obstacle avoidance path of the manipulator. Result: Through experimental simulation analysis, the results showed that: 1) the manipulator of forestry felling & cultivation machine could successfully avoid obstacles and reach the target point in the obstacle environments. 2) Whether in a single obstacle or multiple obstacle environments, the angle transformation of each joint of manipulator was relatively smooth. 3) Compared with the classic RRT algorithm, biasing RRT algorithm and bidirectional RRT algorithm, the proposed path planning algorithm in this study improved the search efficiency by 95.9%, 56.9% and 40.5% respectively, which effectively improved the efficiency of robotic arm obstacle avoidance planning. Conclusion: The proposed obstacle avoidance algorithm of the manipulator of forestry felling & cultivation machine in this paper might have a better obstacle avoidance effect and a faster searching speed, which could reduce the labor intensity of the forestry environments, and could also improve the efficiency of the harvesting, tending and pilling of forestry mechanical equipment.