[Objective]The aim of this study was to explore the changes in soil carbon (C) fluxes after conversion from evergreen broad-leaved forest (natural forest) to plantations for 35 and 38 years in central-subtropical areas, the results will provide a theoretical basis for assessing soil C emissions.[Method]An evergreen broad-leaved forest and two plantations converted from the natural forest, i.e., a Phoebe bournei stand and a Cunninghamia lanceolata stand in Xiqin Forest Farm of Fujian Agriculture and Forestry University were monitored. Four plots (20 m×20 m) were established in each stand and soil carbon dioxide fluxes were measured using an Automated Soil CO₂ Flux System (Li-8100) over 25 months (from September 2014 to September 2016). Soil temperature, soil water content, organic C content, microbial biomass C content, soluble C content, annual litter biomass, fine root biomass (0-20 cm soil layer) and litter C/N were measured.[Results]Results showed that stand conversion significantly reduced soil C fluxes. The annual soil C fluxes decreased from 16.22 tC·hm^-2a^-1 in natural forest to 12.71 and 4.83 tC·hm^-2a^-1 in a Phoebe bournei stand and a Cunninghamia lanceolata stand, reduced by 21.6% and 70.2% respectively. Stand conversion resulted in increased temperature sensitivity of soil respiration. The Q₁₀ values were ordered as follows:evergreen broad-leaved forest (1.97) < P. bournei stand (2.03) < C. lanceolata stand (2.91). The Q₁₀ value of C.lanceolata stand was significantly higher than that of the evergreen broad-leaved forest(P<0.05). Soil temperature explained 89.70%, 88.50%, and 87.90% of the variation in soil respiration rate in the evergreen broad-leaved forest, P. bournei stand and C. lanceolata stand, respectively. There were no significant relationships between soil water content and soil respiration rate (P>0.05). Correlations showed highly significant positive relationships between soil respiration rate and soil organic C content, dissolved organic C, microbial biomass C, annual litter biomass, fine root biomass (0-20 cm soil layer) (P<0.01). Accordingly, the Q₁₀ values were significantly positively correlated with litter C/N ratios, whereas it significantly negatively correlated with annual C fluxes and microbial biomass C (P<0.01). Further analysis showed that soil organic C and microbial biomass C were two important factors for determining the changes in soil respiration rates. However, litter C/N ratios were the most important regulators of Q₁₀ values.[Conclusion]In central-subtropical area, stands conversion from evergreen broad-leaved forest to plantations for 35 and 38 years resulting in significant decreases in soil C fluxes, which were associated by shifts in tree species composition and structure, decreased quantity and quality of litters, fine root biomass, soil organic C and microbial biomass C. Soil temperature drove the seasonal changes in soil respiration, soil organic C and soil microbial biomass C were the key factors determine soil respiration rates, while litter C/N ratio was the most important factor of Q₁₀ values. Our study highlights that soil organic C, soluble C and substrate quality should be incorporated into future models when predicting stand conversion effect on accuracy of soil C emissions.

[Objective] This paper presents an analysis and comprehension of the diversity and structural characteristics of woody plants in the greenbelt attached to urban roads in the Sixth Ring Road of Beijing from two aspects, comprehensively sort out the current situation of urban greening campaign in Beijing, in order to find the problems and gradient changes and provide basic sample data for further dynamic research.[Method]Based on the 0.5 m World View 2 remote sensing image, the roads within 1km outside the 6th Ring Road in Beijing were visually interpreted. Meanwhile, ArcGIS was used to randomly select field survey road sections for the named roads in the area through taking 10% of the total length of each type of roads as the survey length. Woody plant species, DBH, crown breadth and other indicators were investigated for the selected road sections, and the species diversity and tree structure were analyzed. Result]This study recorded a total of 33 families, 61 genera and 77 species of woody plants in the green spaces along the roads in Beijing, including 59 tree species, 15 shrub species and 3 vine species. The most common tree species was Sophora japonica (Japanese pagoda tree), and there were 62 native species in Beijing. The richness and species diversity showed a gradual trend of increase from the inside to the outside of the city along the ring roads. The mean DBH of trees was 24.07 cm, which decreased gradually from the inside to the outside of the city along the ring roads, and the number of the DBH of trees in the grade Ⅱ was the largest. The overall proportion of larger diameter class trees gradually decreases from the inside to the outside of the city, and it was also higher along national roads and hutongs than that of other types of roads. The average crown breadth of trees was 6.33 m, and the crown breadth of grade IV, i.e. 6-8 m, was the most common. The crown breadth of trees between ring roads gradually decreases from the inside to the outside of the city. Among all the types of roads, trees with a large crown breadth along national highways and hutongs occupy a large proportion.[Conclusion]The species diversity in the green spaces along the roads in Beijing is not high, and the dominant tree species is widely planted, especially S. japonica, as Beijing's city tree, its number and frequency are much higher than those of other tree species. The proportion of maturing trees is relatively high, with an uneven distribution, but there are too few juvenile trees, with no necessary supplementary plantings in the later period. The overall crown cover is good, and the crown breadth is distributed evenly in different grades. The green spaces along the roads in Beijing is obviously affected by the process of urbanization, along the ring roads, there is a gradual increase in the change of species and a decrease in the specifications from the inside to the outside of the city. The species richness along urban roads (ring road, main road, secondary main road, branch road, Hutong) is obviously higher than that of roads in the outskirts (expressway, national highway, provincial road,). The larger diameter class trees are mostly distributed along national roads and hutongs, and the crown breadth of trees along roads on the outskirts is larger than that along urban roads.

[Objective]Chemical properties of soils at different altitudes and layers after long-term reservoir water level changes were analyzed to understand the degree of variation of soil environment after years of drastic changes in dry-wet alternation in the fluctuation zone of the Three Gorges Reservoir.[Method] Sample plots were set up in a secondary shrub forest within the typical hydro-fluctuation belt in the Three Gorges Reservoir. According to the water level operation plan of the reservoir area, the pH-value, organic matter, and contents of available N, available P and available K in the soil at different altitudes (145-155, 155-165, 165-175, and 175-185 m) in different soil layers (0-10 and 10-20 cm) were measured in 2008, 2009, 2012, 2014, and 2015 (that is, through 0, 1, 4, 6, and 7 fluctuations of water level, respectively).[Results]Results showed that soil pH-values at all altitudes increased obviously, the pH value at 145-155 m changed from acid (pH6.1) to alkaline (pH8.2), and the pH-values at other altitudes gradually tended to be neutral after 7 fluctuations of water level. The extent of pH variation at different altitudes was:145-155 m > 155-165 m > 165-175 m > 175-185 m. The content of soil organic matter in the flooded area was higher than that of the non-flooded area at 175-185 m. With the increase of flood duration, the content of organic matter in the 0-10 cm soil layer decreased year by year compared with that in 2008, but in the 10-20 cm soil layer it increased first and followed by a decrease. With the increase of the number cycles of water level fluctuation, the contents of soil alkali hydrolysable nitrogen and available potassium showed a downward trend of fluctuation, and the contents in the 0-10 cm soil layer were more sensitive to flooding compared with those in 10-20 cm layer. The alkali hydrolyzed nitrogen in 0-10 cm soil layer decreased most significantly in 2009 and 2015, and compared with 2008, the decrease at all altitudes was by 37.2%-54.7% and 50.6%-65.7%, respectively. Moreover, the decrease of available potassium in 0-10 cm soil layer was the largest in 2009, up to 17.1%-50.8%. The content of available P decreased year by year, and the loss of available P was the biggest among all the available nutrients. After 1, 4, 6 and 7 fluctuations of water level, the content of available phosphorus in 0-10 cm layer significantly decreased by 21.8%, 45.4%, 82.2%, and 90.2%, and the content of available phosphorus in 10-20 cm layer significantly (P<0.01) decreased by 44.3%, 61.5%, 83.5%, and 92%, respectively.[Conclusion]With continual extension of the operation period of the Three Gorges reservoir, the soil properties of the fluctuating zone change gradually, reflected by the increased soil pH-values, the decreased content of organic matter, and the depleted available nutrients. To a certain extent, this provides a new scientific basis for predicting succession process of ecological environment quality and the changes of soil properties in the reservoir area under long-term flooding conditions.

[Objective] This study aimed to explain the formation mechanism of Picea balfouriana tree line in terms of nutrient elements. Effects of different soil temperature and moisture on the growth and physiology, and nutrient concentration (unit mass content)and content in responses to low soil-temperature and water stress(drought and saturated water stress) were studied by simulating changes of soil temperature and moisture.[Method]In this study, 5-year-old P. fouriana seedlings were taken as experimental material. The experiment was conducted in a walk-inartificial climate chamber with a nested design. Five soil temperature regimes (2, 7, 12, 17, 22℃) and three soil moisture treatments (drought treatment, normal moisture treatment and saturated moisture treatment) were set up. A total of 135 seedlings were used in the experiment, and 9 seedlings were randomly selected in each treatment. After 4 months treatments, phenotypic traits, dry mass, total nitrogen and total phosphorus of seedlings were measured and analyzed. At the same time, soil samples were collected to measure total nitrogen and total phosphorus.[Result]Soil temperature treatments had no significant effects on basal diameter and height increment, while soil moisture treatments had significant effects on height increment. Drought treatment significantly reduced height increment at 2℃ and 7℃, however the effect was no longer significant with soil temperature increasing. Soil temperature treatments had no significant influences on nitrogen (N) and phosphorus (P) concentration in soil, while drought stress significantly increased N and P concentration in soil. The N and P concentration in different organs, and N content in annual needles of spruce seedlings were significantly decreased with soil temperature decreasing. Drought and saturated water stress significantly reduced N concentration in annual needles and annual branches. Saturated water stress significantly reduced P concentration in annual needle, and drought stress significantly reduced P concentration in annual branch, stem and root. Drought and saturated water stress significantly decreased N and P content in annual needle and root, and the higher the temperature the effect was more significant.[Conclusion]In the short term, low soil temperature and water stress had no significant limitations on phenotypic traits, while the stress had significant effects on N, P concentration and content, especially in annual needle and root. The deficiency of N and P content in organs of the seedlings caused by extreme climate changes, such as low temperature stress and water stress, is likely to limit the vertical distribution of P. balfouriana in the western of Sichuan province, in China. In addition, there was a significant interaction between soil temperature and moisture treatment, The effects of water stress on nutrient in various organs of the seedlings was significantly reduced with soil temperature decreasing. It was suggested that low soil temperature became the leading factor for the deficiency of nutrient elements in various organs of P. balfouriana seedlings with the increase of altitude.

[Objective]This study aimed to explorethe relationships between leaf morphological structure, photosynthetic characteristics and water physiological characteristics, and the internal causes affecting plant biomass accumulation of Populus euramericana cv. ‘BYu’ in comparison with P. popularis ‘35-44’ and further reveal the drought-resistant of P.euramericana cv.‘BYu’ and P. popularis ‘35-44’, which could lay foundations for the drought physiology research and the promotion of poplar varieties in regional afforestation.[Method]A pot experiment with one-year-old cuttings of P.popularis ‘35-44’ and P.euramericana cv.‘BYu’ was conducted to investigate the effect of different drought stress on leaf area (LA), leaf vein density (LVD), leaf nitrogen use efficiency, photosynthetic characteristics and leaf hydraulic conductance(LHC), and their influence on plant biomass accumulation and drought-resistant ability.[Result]With the increase of drought stress, LVD and leaf nitrogen content per mass(N_mass) of two poplar varieties increased, and LVD increased more and N_mas increased less for P.euramericana cv.‘BYu’.Net photosynthetic rate(P_n), photosynthetic rateper plant(PTL),maximum net photosynthetic rate (P_nmax),daily accumulation of P_n and Tr, K_leaf, water use efficiency(WUE), photosynthetic nitrogen use efficiency(PNUE), LA and plant total biomass(TB) all decreased, with decreased less for P.euramericana cv.‘BYu’.Compared with P.popularis ‘35-44’, P.euramericana cv.‘BYu’ had higher LA, LVD, PNUE, TB,and daily water consumption, lower P_n, K_leaf, WUE, N_mass before and after drought stress, higher PTL, P_nmax, and daily accumulation of Tr under moderate and severe drought stress,and higher P_nmax, daily accumulation of P_n, and Tr under severe drought stress. PTL was more closely related to TB than P_n, and, PNUE was more closely related to than N_mass.[Conclusion]Under drought stress, the leaf morphological structure and physiological characteristics of P.euramericana cv.‘BYu’ presented a balanced constraint relation between inefficient water utilization, efficient adjustment of leaf morphological structure, efficient nitrogen utilization, efficient assimilation of carbon.Drought resistance mechanism of these two varieties wasdifferent, P.euramericana cv.‘BYu’ with strong drought-resistancehad more efficient leaf structure adjustment, P.popularis ‘35-44’ with weak drought-resistancehad more sensitive photosynthetic characteristics to drought. Leaf structure was most associated with drought resistance, followed by photosynthetic characteristics.

[Objective] In this study, effects of different phosphorus levels on growth and root morphological changes of the variety ‘Guinong 5’ seedlings of Rosa roxbunghii Tratt., as well as their interactions with endogenous hormones were studied in order to understand the adaptation strategies of this species under low phosphorus stress. The study would provide scientific basis for phosphorus nutrient management and growth regulation of R. roxbunghii on low phosphorus soil of Karst area.[Method] Five different available phosphorus levels (5,25,45,65 and 85 mg·L^-1) were applied to the culture matrix for growing the seedlings. The growth and root morphological indexes and the endogenous hormones contents in leaves and roots were were determined. The relationship between root morphology and endogenous hormone contents at different phosphorus supplying levels was analyzed.[Result] The seedlings treated with 45 mg·L^-1 phosphorus performed best compared with other treatments, with the fastest growth rate, the greatest biomass of whole plant, the longest main root length, the greatest amount of total root tips, total root length, total volume, total surface area, average diameters, lateral root length and number, and density of first order lateral root. The content of GA₁₊₃ in roots and leaves of seedlings treated with 45 mg·L^-1 phosphorus was the highest and the content of ABA was the lowest. The plant growth was inhibited when the supplying level of phosphorus was lower or more than 45 mg·L^-1, with a significantly reduced biomass, a decreased content of GA₁₊₃ and an increase of ABA as well as decreases in indexes of root morphology mentioned above. The root-shoot ratio, the density of secondary and tertiary lateral roots and the root hair density and length of R. roxbunghii seedlings reached the maximum at 5 mg·L^-1 phosphorus level. The contents of IAA and ZR in the roots and leaves of R. roxbunghii increased with the decrease of phosphorus level. A significant quadratic nonlinear regression relationship was found between the growth indexes, biomass of the plant at different phosphorus supply levels and the contents of IAA, ZR in roots and leaves, and a significant positive correlation and negative correlation with the content of GA₁₊₃ and ABA, respectively. The inhibitory effects of low or high phosphorus supply on plant growth were the results of synergistic effects of changes in IAA, ZR, GA₁₊₃, and ABA content. The inhibition of root growth at low phosphorus level was related to the increase of IAA, ZR and ABA contents and the decrease of GA₁₊₃ in leaves and roots. High concentration of GA₁₊₃ and low concentration of ABA promoted the elongation of main roots and the formation of lateral roots, and high concentration of IAA and ZR promoted the formation, elongation of root hairs and the density of root hairs.[Conclusion] Seedlings treated with 45 mg·L^-1 phosphorus performed best according to growth and root development, in main root length, total amount of root tips, total root length, total volume, total surface area, mean diameters, length and number of lateral roots, the density of first order lateral roots. The plant growth was inhibited when the phosphorus levels were lower or higher than 45 mg·L^-1, and the root morphological indexes mentioned above were decreased. The root-shoot ratio of Rosa roxbunghii seedlings increased, and the density of secondary and tertiary lateral root, root hair and length increased significantly under low phosphorus stress. The content of IAA, ZR, GA₁₊₃, and ABA in leaves and roots of the plant changed due to the changes of phosphorus supplying levels, which co-regulated the growth and root morphology of R. roxbunghii seedlings. The increase of root-shoot ratio, root density, root hair density and the length of second and third order lateral roots was the adaptation strategy of R. roxbunghii seedlings to low phosphorus stress, in which high level of ZR and IAA in roots and leaves played an important promoting and regulating role.

[Objective] In this study, dynamic patterns of sex-specific water and nitrogen use efficiencies in male and female plants of dioecious Litsea cubeba were analyzed. The result provides a theoretical basis for understanding of the dynamic changes of resource allocation of dioecious plants.[Method] The nutrient content (carbon and nitrogen content, the ratio of carbon and nitrogen (C/N)), water use efficiency, as inferred from leaf carbon isotope composition (δ¹³C), and nitrogen use, estimated by leaf nitrogen isotope composition (δ¹⁵N) were measured in male and female plants during 105 and 165 days after flowering (DAF).[Result] 1) The mean leaf δ¹³C values of female and male plants were -29.38‰ and -28.08‰. Leaf δ¹³C values of both male and female plants were significantly affected by sex and development period. Leaf δ¹³C values of the female plants were all lower than the male plants for the five periods. Leaf δ¹³C values of both male and female plants were constantly decreased during the development period. 2) The mean leaf δ¹⁵N values of the female and male plants were 1.90‰ and 2.95‰. Sex and development period also had significant effect on leaf δ¹⁵N values of male and female plants. Leaf δ¹⁵N values of the female plants were lower than the male plants from 105 to 150 DAF (rapid accumulation stage of oil and citral contents). δ¹⁵N values showed double peaks during 105 and 165 DAF, and the largest values were appeared at 105 and 135 DAF. Meanwhile, δ¹⁵N value of the female plant was lowest at 120 DAF, while the lowest value was appeared in the male plant at 165 DAF. 3) The mean leaf carbon contents of the female and male plants were 49.44% and 49.28% respectively. Leaf carbon contents were higher in the female plant than in the male plant at 105 and 120 DAF, while lower in the female plant than in the male plant from 135 DAF to 165 DAF (from accumulation stage to stable stage of oil content). The leaf carbon contents significantly increased with time in the male plant, but not significantly in the female in different periods. 4) The mean leaf nitrogen contents of the female and male plants were 1.71% and 1.51%. Sex had a significant effect on the leaf nitrogen content, and the leaf nitrogen contents of the male plants were lower than the female plants from 105 to 165 DAF (except for 135 DAF). 5) The mean leaf C/N of the female and male plants was 29.15 and 33.72. Sex had a significant effect on C/N, and the female plants had a lower C/N than the male plants, regardless of time. The decreased value of C/N was higher in the male plants than in the male plants from 135 to 165 DAF. 6) There were no correlations between δ¹³C and the nitrogen content and between δ¹³C and δ¹⁵N.[Conclusion] The sexes of the L. cubeba differ in terms of temporal patterns of water use efficiency and nitrogen use. The water use efficiency of female plant was lower than that of male plant, and constantly declined from rapid accumulation stage to stable stage of oil and citral contents. The nitrogen use efficiency of female plant was also lower than that of male plant, and the nitrogen use efficiency of female and male plants showed double peaks. The nitrogen content of male plant was lower than that of female plant, allocating more nitrogen to flower buds for pollen formation. The carbon content of female plant was lower than that of male plant from the rapid accumulation stage to stable stage of oil and citral contents, supplying more carbon for fruit and seed formation.

[Objective] The phenotypic traits of pod and seed from an endangered plant Erythrophleum fordii were measured to investigate the phenotypic diversity and variation pattern of populations. And combing with geographical and climatic information, the factors affecting the phenotypic variation were discussed. This study provides a basis for genetic diversity conservation, restoration, and cultivation of E. fordii.[Method] The phenotypic characteristics of thirteen pods and seeds from 114 individuals of eight natural populations were measured. Nested analysis of variance, multi-comparison, correlation analysis, principal components analysis, and cluster analysis were used to study phenotypic diversity,evolution and adaptive potential, patterns of phenotypic variation, level of phenotypic differentiation, cluster of populations, and the correlation between phenotypic traits and climate factors, respectively.[Result] E. fordii showed a modest level of phenotypic diversity, the range of Shannon-Wiener index is from 1.911 1 (Shape index of seed) to 2.103 9 (Perimeter of pod)with an average of 2.027 8. The range of Shannon-Wiener index of eight populations is from 0.920 9(P6)to 1.885 6(P8) with an average of 1.474 7. The range of variation of variance among the 13 traits was from 7.544 6% (Length of seed)to 18.868 5%(Area of pod)with an average of 12.410 9%. The range of variation of variance among the eight populations was from 8.852 9%(P1) to 13.984 8%(P5) with an average of 12.410 9%. The range of times of maximum and minimum was from 1.395 2(Shape index of seed) to 2.805 6(Number of seeds in pod)with an average of 1.791 7. Analysis of nested variance showed that there was a significant differences (P<0.01) among and within populations, suggesting that abundant variation among and within populations. The within-population variation(40.387 1%) was much larger than the among-population variation(11.948 9%); and the average phenotypic population differentiation coefficient was 21.857 9% with a range from 7.476 5% (Shape index of seed)to 38.674 0% (Width of pod). Correlation analysis revealed that there were significant correlations among most phenotypic traits. The significantly negative correlation between the width of pod, length of seed and perimeter of seed was detected, whereas, there were significantly positive correlations between width of pod and latitude. The pod and seed were mostly found small in the areas with high temperature and rainfall in general, and the size of pod and seed became bigger and bigger along with the increase of the latitude and the decrease of the temperature. Principal component analysis showed that the four principal components added up to 87.382% of the variation. The eight natural populations were divided into three groups by UPGMA cluster analysis based on Euclidean distance calculated from phenotypic traits. The first group was comprised of populations with small pods and small seeds, which are located in the south of the natural distribution. The second group has characteristics of big pods and big seeds, which are located in the north of the natural distribution, and only one population is located in the south of the distribution. Populations with small pods, big and thin seeds are located in the middle of the distribution, belonging to the third group.[Conclusion] E. fordii has the modest level of phenotypic diversity, there were abundant variations among and within populations. The degree of phenotypic variation was slight and stable, and there was low level of population differentiation in E. fordii. Within-population variation was the main source of variation. For germplasm collection and preservation, the number of populations can be reduced while the number of individual trees within populations can be increased, especially the individuals with unique phenotypic characteristics. Rongxian and Longxu of Guangxi are the most important regions for genetic conservation and germplasm collection. Temperature was the most important factor affecting the phenotypic traits and distribution of E. fordii. Pod and seed sizes are the basis for populations clustering.

[Objective] The difference and variation patterns of seed economic properties of 1 000-grain weight,kernel rate,oil yield, and seed oil fatty acid of Handeliodendron bodinieri among provenances were studied,and the best provenance for biodiesel material was evaluated and screened.[Method] Seeds of H. bodinieri from five provenances including Leye, Tianlin, Fengshan, and Huanjiang in Guangxi, and Dushan in Guizhou were used as experimental materials. The oil yield of seed,seed kernel and seed coat was determined by Soxhlet extraction after measuring the 1 000-grain weight and kernel rate. The fatty acid composition and content of seed oil were analyzed by gas chromatography. Correlation analysis among seed economic traits and between the traits and geographic-climatic factors were conducted,and cluster analysis of different provenances was performed. On the basis of fuel property of fatty acids,evaluation of different provenances was conducted.[Result] 1) The difference in oil content of seed coat among different provenances was not significant,but extremely significant (P<0.01) in 1 000-grain weight,kernel rate,seed oil yield and seed kernel oil yield,and the average coefficient of variation of these five traits among provenances was 13.7%,in which,1 000-grain weight (210.02 g),kernel rate (68.89%),seed oil yield (43.23 g·(100 g)^-1) and seed kernel oil yield (56.56 g·(100 g)^-1) of Fengshan provenance were all the highest except for seed coat oil yield. 2) 14 long chain fatty acids,including 6 saturated fatty acid,5 monounsaturated fatty acids and 3 polyunsaturated fatty acids were found in the seed oil of H. bodinieri,among which the average mass fraction of unsaturated fatty acid was as high as 94.08%,and the average coefficient of variation among provenances was only 0.53%. Eight major fatty acids (mass fraction >1%) accounted for 98.19% of the total fatty acid of seed oil,and their average coefficient of variation among provenances was 7.21%,among them the average mass fraction of nervonic acid (7.80%) was ranked the 4^th in the list of woody plants known to contain nerve acid. 3)The correlation analysis showed that there was an extremely significant positive correlation(P<0.01,R=0.997) between oil yield of seed and kernel. There were many significant or extremely significant correlations between the major fatty acids except linolenic acid. These main fatty acids were divided into two groups according to the length of carbon chain 22,and promoted each other within group,but reversely promoted between groups. There were extremely significant correlations(P<0.01)among 1 000-grain weight with linolenic acid,kernel rate with saturated and unsaturated fatty acids,seed oil yield with palmitic acid,linoleic acid,erucic acid and single unsaturated fatty acids,and their correlation coefficients were -0.983,-0.964,0.964,-0.998,-0.981,0.995 and 0.976,respectively. The correlations between seed economic traits and geographic-climatic factors were not significant. 4) The cluster analysis showed that five provenances were clustered in 3 groups,in which,2 provenances of Leye and Dushan were clustered in one group,2 provenances of Tianlin and Huanjiang were clustered in one group,and Fengshan provenance was separately clustered in one group. 5) As raw material for biodiesel, the tetracosanoic acid and nervonic acid must be isolated from the seed oil of H. bodinieri which could not meet the CFPP requirement of -10℃. All the evaluated values of Fengshan provenance were the best.[Conclusion] There are abundant variation among provenance of seed economic traits of 1 000-grain weight,kernel rate,seed oil yield,seed kernel oil yield of H. bodinieri. The economic utilization value of seed oil is higher and the low temperature fluidity of seed oil is better. Mass fractions of major fatty acids are in a stable condition with a small degree of dispersion and variation among provenances. The seed economic traits are not significantly affected by geographic-climatic factors and have the characteristics of random variation among provenances,and Fengshan is the best provenance for raw material for biodiesel.

[Objective] Monitoring the spatial distribution pattern of forest in the water source area of the middle-route of the south-to-north water diversion project from 2000 to 2015 and studying the process mechanism of forest dynamic change provide a theoretical basis for forest ecosystem protection and water quality safety in the study area.[Method] Based on the 30 m resolution HJ-1 A/B CCD images(2010, 2015)and Landsat TM images(2000), the object-based decision tree classification method was used to obtain the land cover and the pixel dichotomy model for fractional vegetation coverage(FVC)estimation by NDVI.[Result] The classification accuracy K value went up to 89.4%, 86.9% and 84.4%, respectively and the user's accuracy of forest was 98% in 2000, 96% in 2010 and 94% in 2015. The result showed that the acreage of forest increased continually from 2000 to 2015, and mainly transferred from grassland, cropland and construction land, due to the implementation of ecological projects, such as Grain for Green. However, because of the mass migration and the continuous development of regional economy, part of the forest acreage turned to cropland, grassland and construction land. Due to the remarkable implementation of ecological projects, in the statistical analysis of cities, the increments of forest area in Shiyan city and Ankang city were the most, reaching 1 383.9 km² and 1 344.8 km²,respectively. From 2000 to 2015, the FVC of forest increased with a rate of 25.4%. The acreage with FVC above 0.6 took account of the largest proportion of forest area.[Conclusion] In summary, not only the acreage of forest, but also the FVC of forest both increased significantly. Thus the quality of forest in the water source area has been improved generally, which form the vegetation protective layer on the surface to reduce the risk of water erosion and ditch erosion, so as to improve the soil and water conservation capacity of the water source area.

[Objective] This study integrated multi-temporal aerial photographs and DEM derived from airborne LiDAR data to calculate the forest canopy height of Cunninghamia lanceolata and monitor the variation of growth quantitatively.[Method] First of all, high accuracy digital elevation model beneath canopy and forestry digital surface model were constructed based on classified LiDAR point cloud data. Digital surface models were then created by applying an automated stereo-matching algorithm to the scanning copy of aerial photographs. These multi-temporal canopy heights were obtained by subtracting the LiDAR ground elevations from the two kinds of DSM. Using historical aerial photographs of 1996, 2004 and digital aerial photographs, LiDAR data of 2014, multi-temporal CHMs were reconstructed within a period of 18 years, and the accuracy was evaluated and analyzed.[Result] 1) The R² between the canopy height models acquired by LiDAR data and corresponding digital aerial photographs in 2014 is 0.52, and the root mean square error is 1.79 m. 2) Compared with the measurements from field plots, our data showed an accuracy of 85.00% with mean absolute errorand mean relative error of 1.59 m and 15.00%, and the maximum absolute error and maximum relative error of 3.45 m and 30.80% respectively. 3) Combined with the aerial photos of year 1996, 2004 and 2014, these multi-temporal canopy height models of Cunninghamia lanceolata plantation have a similar growth trend to the predicted growth curve.[Conclusion] Based on the results, utilizing aerial photographs can characterize the variation of canopy height in the sunny slope of mountainous terrain. However, for forests located in the valley bottom, the canopy height would be under estimated with aerial photographs. Multi-temporal aerial photographs combining with the high accuracy DEM can reflect the variation of overstory's height, which provide the possibility for monitoring the forest's growth trend and access the forest's productivity.

[Objective] The important pest mites that infest Castanea mollissima,an economic forest species, and Cunninghamia lanceolata, have been considered to be the same mites, Oligonychus ununguis. However, previous studies have shown that reproductive isolation exists between the C. mollissima population from Shandong Province(TSBL) and the C. lanceolata population from Zhejiang Province(ZJSM) of O. ununguis and the reproductive isolation is not caused by geographic isolation and the endosymbionts that can manipulate the reproduction of their hosts. The two populations have been differentiated into two independent species, but whether the differentiation is related to adaptation to different host plants has not been determined. This study was carried out to clarify the differentiation reasons and enrich the speciation theory.[Method] Three female adult mites were randomly selected from the C. mollissima population and the C. lanceolata population respectively which collected previously to be used to hybridization experiment. The genomic DNA was extracted from a single female adult. The 28S rDNA sequences were amplified used the primers designed according to the conserved sequences of the 28S rDNA of other mites in Oligonychus. The amplified products were purified and sequenced. The 28S rDNA sequences of the two populations were compared and the phylogenetic tree of Oligonychus was constructed based on the 28S rDNA sequences. The differentiation reasons of these two populations were analyzed combined with previous studies.[Result] The 28S rDNA sequences of three individuals in each population were identical, without intraspecific variation. The interpopulation sequence identity and the genetic distance between the C. mollissima population and the C. lanceolata population based on 28S rDNA sequences were 98.3% and 1.7% respectively. The phylogenetic tree of Oligonychus based on 28S rDNA sequences showed that O. hondoensis collected from Cryptomeria japonica in Japan was the closest relative of the C. lanceolata population, while O. castaneae collected from Castanea crenata in Japan was the closest relative of the C. mollissima population.[Conclusion] The spider mites on C. mollissima and C. lanceolata are probably two independent species rather than differentiated from the same kind of spider mite because of adaptation to different host plants.

[Objective] The present study was carried out in order to clarify the relationship between the percentage of Pinus yunnanensis shoots with beetles and trap catches of Tomicus minor (Coleoptera:Scolytidae), and furthermore, to provide technical support for population monitoring and controlling of the T. minor pest in the future.[Method]The shoot damages by Tomicus were investigated by random branch sampling method with a pruner in two different damage level sites of Pupeng and Xiazhuang, Xiangyun County, Yunnan province. The adults were trapped by aggregation pheromone of T. minor during the period from shoots transferring to trunk, in order to evaluate the population flight dynamics and analyze the relationship between the percentage of shoots infected with beetles and trap catches.[Result]T. minor and T. yunnanensis were two dominant Tomicus species in Pupeng and Xiazhuang forest sites. T. minor accounted for 49.75% with sex ratio 1.06:1, however, T. yunnanensis consisted of 50.25% with sex ratio 1.32:1 in the Pupeng forest site. In Xiazhuang forest site, it accounted for 54% of T. minor with sex ratio 1.45:1, and for 46% of T. yunnanensis with sex ratio 1.88:1, respectively. The percentage of shoots with beetles gradually reduced from top crown to bottom crown in Pupeng and Xiazhuang sampling locations, where the density of the Pupeng population was ca. 10 times higher than that of Xiazhuang population. The population flight dynamics of T. minor in Pupeng site showed the same trend as that of Xiazhuang, that is, adult flight began in mid-November and ended in late May of the next year. The peak period of adults' flight activities was from early March to late April. The number of natural enemies and the number of the pests in traps had obvious following phenomena. The traps caught more number of males than females with sex ratio ranging from 1:1.09 to 1.71 (♀:♂). There was a linear positive correlation between the percentage of insect-infected shoots (y) and the amount of the trap catches (x), the fitting function formula was y=0.002 4x + 0.060 1 (R²=0.67) in high population densities area (Pupeng), and y=0.003 2x-0.004 3 (R²=0.71) in low population densities area (Xiazhuang).[Conclusion]This study clarified the distribution patterns of T. minor in the tree crown of Yunnan pine with high and low pest population densities. Furthermore, the aggregation pheromone trapping test could be regard as an effective method to monitor the population dynamic of T. minor in the forest. The trapping amount of pests was positively and linearly correlated with percentage of shoots infected with beetles, suggesting that the number of trap catches could reveal the percentage of shoots infected with beetles.

[Objective] Reasonable micro-pit surface texture has been proved to improve the friction between birch and cemented carbide surfaces and to reduce the friction coefficient. The aims of this study are to discuss the influences of wood moisture content, the direction of wood section and fiber, and the speed of motion on the coefficient of friction, and provide reference and guidance for designing more reasonable texture forms.[Method] Ash and pine were selected as the research objects, the influences of wood moisture content, wood section and fiber direction and sliding speed on the friction coefficient of different micro-pits structures were assessed and compared.[Result] Compared with the non micro-pits texture surface, it was found that when the diameter of the pit is 60 μm and the moisture content is 67%±3%, the friction coefficient showed the largest decrease.The friction coefficient on the surface of the ash decreased from 0.151 to 0.091, and decreased extent reached 39.7%, and the friction coefficient decreased from 0.241 to 0.164, with a 32.0% drop on the surface of pine. The difference among the directions of wood fiber on the radial section has little effect on the friction coefficient. On the cross section, the smaller the pit diameter, the higher the friction coefficient was obtained. The influences of sliding speed on friction coefficient exhibited a great relationship with the wood moisture content during friction process. The coefficient of surface friction decreased with the increase of sliding speed, the friction coefficient curve with d=60 μm declined more obviously when the moisture content with green condition showed higher than that of surface with no micro-texture. The friction coefficient of the plane surface was reduced from 0.160 to 0.134, the decrease extent was 16.3%, and the friction coefficient of the surface with micro-texture (d=60 μm) reduced from 0.124 to 0.071, the decrease extent was 42.7%.[Conclusion] The wood moisture content has a great influence on the friction coefficient between micro-pit surface texture and wood, and the free water in wood can reduce the friction coefficient between cemented carbide and wood surface. The smaller the diameter of micro-pits, the greater the average change rate of contact angle, and the higher surface spreading speed were obtained,moreover,the friction was improved better.

Urban forest is an important green infrastructure alleviating urban heat island. This study was aimed to explore the internal and external factors influcening the cooling impacts of urban forest and to understand the mechanisms of such influence. It provides an scientific basis for optimization of urban forest structure and alleviation of the effects of urban heat island.The internal factors that affect urban forest cooling effect at individual tree scale were tree species, canopy structure and crown shape, while at stand scale, the factors mainly contained forest type, forest structure, green biomass and shape and size of the stand, moreover, the cooling effect of urban forest was studied mainly by remote sensing method at urban scale, and the representative indices included NDVI, LAI and landscape ecological indicators. In addition, the external factors that affected the cooling effect of urban forest included non-biological factors such as climate and ground types, as well as forest management. The internal and external factors affected the cooling effect of urban forest jointly by affecting the flow and exchange of energy inside and outside the forest.To alleviate the effect of urban heat island, on the one hand, it is necessary to strengthen theoretical research, attach importance to the theory of temperature field, and study the relationship between stand structure and energy transmission in urban forest by combining ground observation and remote sensing. On the other hand, it is important to strengthen the management of urban forests, optimize the stand structure from the perspective of promoting heat exchange, and rationally match buildings, forests and water to maximize the cooling effect.

Liquid crystal is a special phase state with partially ordered arrangement, and shows remarkable difference between completely ordered solid state and completely disordered liquid state. As the representative liquid crystal, cellulose nanocrystal (CNC) is currently prepared by the strong acid hydrolysis of natural cellulose, including wood, bamboo, cotton, tunicate, bacteria and so on. The individual CNC is randomly dispersed in the CNC suspension at low concentration solution. With the concentration increased, the randomly dispersed CNCs spontaneously arrange to form cholesteric liquid crystals. Due to the special optical properties such as bragg reflection, polarized light dichroism and rotary polarization, cholesteric liquid crystals from CNCs can be applied as anti-counterfeiting optical information storage, intelligent windows and liquid crystal display. In this paper, the preparation and regulation method of cholesteric liquid crystals from CNCs are introduced. The preparation and comparison of different CNCs from a large variety of resources are proposed. The regulation effects of physical factors (ultrasonic, temperature, vacuum drying and magnetic field and other regulatory factors) and chemical factors (electrolyte and additives and other regulatory factors) on the pitch of cholesteric liquid crystals from CNCs are be discussed in order to make a theoretical contribution to the regulation preparation of cholesteric liquid crystal. In addition, the formation mechanism, the structure and optical properties of cholesteric liquid crystals from CNCs are introduced, and the application status in thermo-sensitive functional materials, optoelectronic functional materials and chiral mesoporous materials are summarized. The future development trends of cholesteric liquid crystals from CNCs are also discussed as the following:1) Adjusting the preparation method to obtain CNC with negative charges, rod-shape and small size distribution which are all necessary for CNC to form ideal cholesteric structure; 2) Developing less time consuming and greener preparation method of cholesteric liquid instead of slow evaporation self-assembly method; 3) Establishing the relevant regulatory model to achieve controllable preparation of cholesteric liquid crystals from CNC; 4) Copying stable chiral nematic structure from CNCs and developing high performance multi-functional materials in the future.

[Objective]The objective of the research is to predict the potential geographical distributions of Dothistroma pini under the climate change, and to study the effects of climatic factors on the geographical distribution.[Method] Based on the known distribution areas of D. pini and related climate data, combined with the CCSM4 climate model data released by the Intergovernmental Panel on Climate Change (IPCC) for future climate change scenarios, the maximum entropy model (MaxEnt) was used to predict the potential suitable geographical distributions of D. pini.[Result]The results showed that the principal geographical distribution areas of D. pini were Heilongjiang, Jilin, Liaoning, northeastern Inner Mongolia and Yunnan. The analysis of Jackknife showed that factors such as precipitation in June, average highest temperature in November and precipitation in the coldest quarter had important influences on the geographical distribution areas of D. pini. Under different scenarios of climate change in the future, the total area of suitable geographical distributions is on the rise, with an increase range of 15.66% to 18.29%. The suitable distribution areas of each grade in northern Shandong, Hebei and Shanxi, central and southern Shaanxi, southeastern Gansu, northern and southern Sichuan, western liaoning and eastern Inner Mongolia increased, and the appropriate grade increased.[Conclusion] The MaxEnt model is proved high reliability to determine the geographic distribution range of D. pini. Under different scenarios of climate change in the future, the principal geographical distribution areas in border area of Yunnan and Sichuan, northeast three provinces and northeast Inner Mongolia show a trend of fragmented. The centroid suitable for the D. pini distribution tends to spread from northeast to north and northwest in China.

[Objective] Chinese bayberry (Myrica rubar Sieb. et Zucc.) is an evergreen tree species and suitable for growing in weak acid soil, and it has been cultivated mainly in southern China. Bayberry fruit is ripe in early summer and delicious with attractive color, flavor, and high economic and medicinal value. M. cerifera is suitable for growing in poor alkaline soil, and different from M. rubar. It is of practical significance to study the grafting compatibility and genetic relationship between M. rubar and M. cerifera for expanding M. rubar cultivation.[Method] For three consecutive years, M. rubra and M. cerifera were used as rootstocks, and four cultivated varieties (‘Biqizhong’, ‘Dongkui’, ‘Xiazhihong’ and ‘Shuijingzhong’) as scions, and the interspecific grafting was carried out on the beach of Yuyao, Zhejiang Province (soil pH8.01). The genetic relationship between M. rubar and M. cerifera was identified and clustered based on SSR. After three years of grafting experiments, survival rate of grafting and related indexes of rootstock-scion combinations were investigated.[Results] The grafting survival rate of rootstock-scion combinations of M. rubra was 70.08-83.47%, among which the grafting survival rate of scion of ‘Xiazhihong’ was highest (81.98%), and the grafting survival rate of ‘Biqizhong’ was the second (80.43%). The grafting survival rate of rootstock-scion combinations of M. cerifera were 27.51%-38.29%, among which the grafting survival rate of scion ‘Dongkui’ was highest (34.88%). The grafting survival rate of M. cerifera rootstock-scion combinations was significantly lower than that of M. rubar rootstock-scion combinations. T-test showed that BQ4-6, DK4-6 and SJ4-6 of M. cerifera rootstock-scion combinations had significantly higher crown diameter, dry rootstock perimeter and plant height than those of M. rubra combinations, respectively. The correlation analysis of six indexes showed that there was a significant positive correlation between grafting survival rate and plant height and crown diameter, and a negative correlation between plant height and rootstock height in both rootstock populations over three consecutive years experiment. A total of 127 SSR markers were used to detect DNA polymorphisms of 2 rootstocks and 4 scions, these materials were clustered into 3 groups, and the genetic similarity between M. cerifera and M. rubra was 0.31. The relationship between rootstock of M. rubra and ‘Xiazhihong’ was the closest, followed by ‘Biqizhong’. The rootstock of M. cerifera had the highest relationship coefficients with ‘Dongkui’; it was demonstrated that the closer genetic relationship the higher grafting survival rate.[Conclusion] This study proved that M. cerifera used as rootstocks had to a certain degree grafting affinity with M. rubra scion, which was more suitable than M. rubra rootstocks for growing in alkali soil.

[Objective]In this study, we investigated the role of medium components in somatic embryo maturation, in order to further improve the quality and quantity of somatic embryos.[Method]The embryogenic cells were incubated for 10 days in the solid proliferation medium. Sterile electronic scales (75% ethanol wipe, ultraviolet sterilize 30 min) were used to weigh 1 g embryonic cells, a 50 mL sterile measuring cylinder (ultraviolet sterilization 30 min) was used to measure 30 mL liquid medium which was poured into a 100 mL conical flask. Then, 1 gram embryonic cells were transferred into a 100 mL conical flask which was transferred into a constant temperature incubator shaker. The culture was incubated 7-8 days in darkness at 25℃, 90 r·min^-1. Subsequently, suspension cells (precipitated volume 3 mL) were taken for the subculture. The subculture was proliferated once a week until all embryogenic cells were evenly dispersed in the culture medium. The suspension cells of 2 mL (fresh mass 200 mg) from the forth culture were sprayed on solid mature media which contained various components of maltose (30,45,60 g·L^-1), abscisic acid (ABA) (0,5,10,20,30,50 mg·L^-1), polyethylene glycol (PEG8000) (0,50,75,100,125,150 g·L^-1), activated carbon (AC) (1 g·L^-1, 2 g·L^-1, 3 g·L^-1), coagulating agent (agar:6, 8, 10, 12 g·L^-1; Phytagel 2, 2.5, 3, 3.5 g·L^-1) and the combination of maltose, ABA and PEG8000.[Result]During the development and maturation of somatic embryos (cell line #1337), the number of somatic embryos obtained from maltose 45 g·L^-1 medium increased significantly; When the ABA concentration ranged from 5 mg·L^-1 to 20 mg·L^-1, the number of somatic embryos increased significantly with ABA concentration, and with abscisic acid (ABA) concentration in 20 mg·L^-1, the maximum quantity of somatic embryos was obtained; The optimal concentration of polyethylene glycol (PEG8000) and activated carbon (AC) for somatic embryogenesis was 125 and 2 g·L^-1, respectively; Agar powder, as coagulant, was added to the mature medium that could not solidify; phytagel was more suitable for solidifying mature medium. phytagel of 3 g·L^-1 was the optimum concentration of somatic embryo maturation. The orthogonal experiment showed that maltose 45 g·L^-1, ABA 10 mg·L^-1, and PEG8000 125 g·L^-1 were the media on which the embryogenic cells (cell line #1337, #1537, #1637) produced the most somatic embryos among the nine maturation medium combinations. Among different combinations of maltose, ABA and PEG8000, the productivity of somatic embryos produced from different clones showed different trends. The optimal combination for somatic embryo development and maturation from embryogenic cell #1337 was maltose 45 g·L^-1, ABA 10 mg·L^-1, PEG8000 125 g·L^-1; from #1537 and #1637, the optimal combination was maltose 30 g·L^-1, ABA 10 mg·L^-1, PEG8000 125 g·L^-1; PEG8000 had the biggest range in the three clones, and thus, PEG8000 had the most important effect on somatic embryos development and maturation of Pinus thunbergii.[Conclusion]In process of somatic embryo maturation (#1337), maltose 45 g·L^-1, ABA 20-30 mg·L^-1, PEG8000 125g·L^-1, AC 2 g·L^-1 and 3 g·L^-1 phytagel promoted somatic embryo maturation. The optimal combination for Japanese black pine somatic embryo maturation is maltose concentration 30 g·L^-1, ABA 10mg·L^-1 and PEG8000 125g·L^-1.

[Objective] In this paper, the method based on linear spectral clustering (LSC) superpixel was applied in the field of forest pest control, which was able to intelligently monitor dead trees in forest pest images taken from the unmanned aerial vehicle (UAV), and provide technological support for intelligently monitoring of forest pests.[Method]The UAV images of pine forests infected by Bursaphelenchus xylophilus and Dendroctonus valens respectively from Hubei and Liaoning provinces were chosen as the experiment data. Firstly, the linear spectral clustering superpixel algorithm was used to divide the image into many compact and uniform superpixels. Then, on a basis of the different color characteristics of dead trees and healthy trees, the superpixels which might be dead trees were initially extracted. Next, based on the different texture features of dead trees and other red disturbances, the area density and the lacunarity of the initially extracted superpixels were calculated. Finally, the support vector machine based on texture features was used to classify the initially extracted superpixels to detect dead trees in the image.[Result]The method based on LSC superpixel was able to exclude other interference objects that were similar in color to dead trees, and accurately extracted dead trees. The 35 UAV images of the pest-infected pine forest were used for comparing quantitatively this method with the other two methods. One is threshold segmentation method based on vegetation color index, and the other is simple linear iterative clustering (SLIC) superpixel and random forest method. Furthermore, the three evaluation indexes:intersection over union, the false alarm rate and the misdetection rate were used to quantitatively compare and analyze the three methods. The experimental results showed that the algorithm based on LSC superpixel and SVM was the most accurate to detect dead trees. The mean of intersection over union between this method's result and manual detection result was more than 58% and the false alarm rate and the misdetection rate were better than the other two algorithms.[Conclusion] Our results showed that the dead tree monitoring method based on LSC superpixel was able to detect and locate dead trees quickly and precisely in the UAV pine forest images and effectively protect forest resources.

[Objective] To observe the pit morphology and distribution in moso bamboo, resin casting, a very proper way to obtain three-dimensional duplicate of pits, was applied.[Method] A two-component resin BS was used to complete the following procedures, infiltration of resin, resin curing, corrosion of bamboo tissue and dry cleaning in order. Resin casts of different types of individual cell and cells within certain scope served to reveal characteristics of pits in cell wall, pit pairs between cells and channels in vascular bundle. Moreover, a combination with observing bamboo sections was able to make verification of result getting from two ways.[Result] Pits in metaxylem vessels of moso bamboo presented a high selectivity of distribution, that is, large scale of pits were centered in single side of cell wall near to the geometric center of vascular bundle, though pits in the other side turned to be the opposite. And clear pit border structure was found. Diameter of pit aperture and pit membrane of vessel resin casts were 0.9-2.7 μm and 1.1-3.8 μm respectively. There were some smaller metaxylem vessel elements scattered or arranged adjacent connecting with bordered pit. As for parenchyma cells within the vascular bundle, pits were more and larger than those in the ground tissue. And parenchyma cells adjacent to metaxylem showed particularity. Pits in fiber cells were in sparse distribution with small openings, long and narrow cavities and suspect pit borders. Cells in vascular bundle connected each other through the pit and formatted space networks further.[Conclusion] Resin casting, which is capable of showing the pit stereo structure and reflecting diffusion permeation of specific fluid inside bamboo both directly and objectively, is a suitable method for investigating pits in moso bamboo.