Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Naturalness evaluation of rivers based on the fuzzy comprehensive evaluation and the grey correlation analysis
YAN Lin, MA Lan, PAN Chengzhong, ZHANG Dong, SUN Zhanwei, ZHANG Jinge, LIU Jingjing, LI Junyou
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.2020.20190485
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  Objective  To restore and better protect the naturalness of Yongding River, one of the five major rivers in Haihe River Basin, the current study is aimed at the naturalness evaluation of it based on the close-to-nature concept, which is of grate significance of the drinking water safety of residents in Beijing and the water environment of Haihe River Basin.   Method  Taking the Beijing gorge section of Yongding River as the study subject, the evaluation index system of river naturalness was constructed with 25 qualitative and quantitative indexes selected from five aspects, namely, hydrological elements, cross-sectional configuration, physical and chemical properties of water body, riparian zone conditions and social ecological value of river. Then, the weight of each index in the evaluation system was calculated with the weighting method of analytic hierarchy process intergrated with the entropy weight method before the naturalness of the river is evaluated and the natural grade is determined employing the fuzzy comprehensive evaluation method and the grey correlation analysis respectively.  Result  The naturalness of the river evaluated employing fuzzy comprehensive evaluation method is generally consistent with that using the grey correlation analysis, and among the 21 river segments, the natural, near-natural, degraded and artificial river segments accounted for 14.29%, 28.57%, 46.62% and 9.52% of the total river length, respectively, and the length is about 7.5, 15.0, 25.0 and 5.0 km.  Conclusion  In general, most of the investigated river segments are being degraded, but they all still display potential in restoring the naturalness and the fuzzy comprehensive evaluation method and grey correlation analysis are both feasible methods for river naturalness evaluation. [Ch, 3 tab. 27 ref.]
Study on rapid propagation system of superior clones in Cryptomeria fortunei
WANG Chen, ZHANG Junhong, ZHANG Miao, XU Wenting, LOU Xiongzhen, TONG Zaikang
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190484
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  Objective  The induced clustered buds of Cryptomeria fortunei have strong differentiative capacity but insufficient elongation ability. In order to obtain the optimum medium of adventitious bud induction, proliferation, elongation culture and rooting induction, the rapid propagation system of C. fortunei was established.  Method  The annual shoot from 20-year-old C. fortunei were used as explants; the orthogonal test design was used to select the optimum medium. The propagation system of C. fortunei includes induction, proliferation, elongation, rooting and transplant.  Result  ① Adventitious buds from three clones could be induced on MS, DCR and WPM basic medium supplemented with different combinations of 6-BA, IBA and CH. But the proliferation ability of buds varied significantly among different mediums. When clones were cultured in WPM medium with 1.0 mg·L−1 6-BA and 0.1 mg·L−1 IBA, the induction rate and proliferation coefficient was the highest, which was 100% and 9.13, respectively. ②When three clones of C. fortunei were subcultured alternately with high concentration hormone and low concentration hormone, the effective shoot growth rate reached 456.87%. ③ The most suitable medium for the C. fortunei rooting was DCR medium with 0.1 mg·L−1 IBA, under which the rooting rate ratio was 100%. ④The rooted seedlings were transplanted to a mixed matrix with equal vermiculite and peat, after 15−20 days of seedling hardening, and the survival rate was 96.70%. Therefore, the potential propagation ability is 3 865 seedlings per maternal plant per year.  Conclusion  Thus, an efficient propagation technology for C. fortunei was established, which laid a technical foundation for industrialization of improved varieties. [Ch, 1 fig. 5 tab. 23 ref.]
Drying characteristics and drying schedule developed of Acacia melanoxylon wood
ZHOU Fan, ZHOU Yongdong, GAO Xin, FU Zongying, HOU Junfeng, WENG Xiang, LIN Shaohui
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190394
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  Objective  In order to provide the technical support for promoting the practical development and utilization of blackwood (Acacia melanoxylon) planted in China, its drying characteristics were investigated, and further its suitable drying schedule was drawn up.  Method  The drying characteristics of blackwood were determined using the 100 ℃ test method. The kiln drying experiments were conducted on the lumber of 25 mm in thickness to develop a suitable drying tecchnique.  Result  The main drying defects were initial cracking and twist deformation. The cross-sectional deformation degree was light, and there were no internal cracks. The blackwood was moderately easy to dry with the drying speed. The blackwood was a medium density hardwood with the air-dry density at 15% moisture content of 0.619 g·cm−3. Applying the proposed drying technique, the drying period of lumber was 268.0 h (11.2 d) as the moisture content of wood decreased from 110.40% to 8.42%. The drying rate remained relatively constant with an average value of 0.38%·h−1 during the whole process.  Conclusion  The findings provide the scientific basis for the actual production of kiln drying to ensure drying quality of the blackwood. [Ch, 2 fig. 6 tab. 25 ref.]
Differences and influencing factors of soil moisture in Karst microhabitats in southeast Yunnan
KUANG Yuanyuan, FAN Tao
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190383
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  Objective  This study aims to analyze differences in soil moisture and influencing factors of karst microhabitats of the eastern Yunnan Plateau, so as to provide scientific basis for the restoration of karst ecosystems.  Method  We studied karst niches (stone ditch, stone pit, soil surface) with different vegetation types, including limestone shrub, Pistacia weinmannifolia secondary forest and Pinus yunnanensis artificial mature forest under the forest-lake basin of Puzhehei karst.  Result  (1) In each niche soil moisture was significantly higher in the rainy season than in the dry season(P<0.05), and the order of average soil moisture was stone ditch (42.24%)>stone pit (41.63%)>soil surface (32.98%). (2) With natural and artificial restoration of limestone shrub, soil moisture increased from natural secondary forest over Pinus yunnanensis plantation to limestone shrub. Pistacia weinmannifolia secondary forest (35.80%)>Pinus yunnanensis artificial mature forest (31.67%)>limestone shrub (29.36%). (3) The difference in soil moisture in karst niches was influenced by the type of habitats, soil properties and vegetation type. Vegetation often preferred the karst niches of stone pit and stone ditch with superior habitat conditions.  Conclusion  Vegetation restoration in karst rocky desertification areas should be combined with vegetation communities and niche types, and stone ditch and stone pit niches should be given priority to vegetation restoration. The combination of natural restoration and artificial restoration can effectively improve karst ecosystems. [Ch, 4 fig. 2 tab. 28 ref.]
Growth, photosynthesis and ultrastructure of mesophyll cells for Cercidiphyllum japonicum seedlings with shading in summer
LI Donglin, JIN Yaqin, CUI Mengfan, HUANG Linxi, PEI Wenhui
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190370
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  Objective  To provide a scientific basis for seedling breeding and population protection, the effects of shading treatment on the growth and physiological functions of Cercidiphyllum japonicum seedlings were analyzed.  Method  With single factor random block design was adopted, using a LI-6400 portable photosynthetic system, a series of shading experiments were conducted on C. japonicum seedlings to study the effects of light on physiological characteristics, diurnal variation of net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and intercellular CO2 concentration (Ci) with seedlings being measured in summer under four light treatments: full light (L0), 55% transmittance (L1), 25% transmittance (L2), and 10% transmittance (L3). At the same time, changes in growth, in morphological indexes, and in the ultrastructure of leaf mesophyll cells were observed by sampling and transmission electron microscope technique.  Result  (1) Shading affected the leaf water content (LWC) and morphology compared to the control; with an increase in shading intensity, LWC increased (P<0.05), single leaf area (SLA) increased (P<0.05) too, both single leaf dry weight (SLWd) and lamina mass per unit area (LMA) decreased (P<0.05), and lamina area per unit mass (LAM) increased (P<0.05). (2) Shading had a strong effect on photosynthesis of seedlings. The “noon break” did not appear during the course of the day. The peak value appeared at 14:00, and other treatments were relatively mild with the peak value appearing at 12:00. The variation curve for Gs was similar to Pn, and Ci basically showed a concave change. The daily average for Pn, Gs, and Tr were L0>L1>L2>L3, but the order of Ci was reversed. (3) Chlorophyll and carotenoid content in leaves increased significantly with shading condition (P<0.05), and both chlorophyll and carotenoid content increased progressively with an increase of shading intensity (P<0.05). Long-term shading improved the light capture ability of leaves. (4) With full light: the outline of cells in the mesophyll tissue could be identified, the number of chloroplasts was small, the arrangement of chloroplasts was close to parallel to the cell wall, there was a large cavity in the center of the cells, the arrangement of thylakoid body was uniform, and the starch granules and osmium granules were few. With shading, the number of chloroplasts increased, the proportion of chloroplasts in the whole cell increased, the shape of chloroplasts gradually became spherical or oval, the number of starch grains increased, and the thickness of thylakoid lamellar was so. (5) For intensity shading L2 and L3, height (H) and basal diameter (D) decreased (P<0.05), the biomass model D2H decreased significantly (P<0.05), and normal growth and development of seedlings affected. However, there were no significant differences between growth indexes of seedlings for L1 (mild shade) compared to L0 (P>0.05). Thus, intensity shading has a great effect on the growth of seedlings.  Conclusion  The mild shading possibly beneficial for the growth environment of forests and having no obvious inhibitory effect on seedling growth, but the effective radiation intensity should be more than 55% of natural light intensity. [Ch, 3 fig. 4 tab. 29 ref.]
Diversity and flora of wetland plants of Changxing County, Zhejiang Province
LIU Zheng, LI Ying, ZHU Pei, CHU Xudong, HE Guoqing, SUN Yong
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190436
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  Objective  Wetland is a precious natural resource and an important ecosystem with irreplaceable functions. The wetlands in Changxing County play an important role in Zhejiang Province. A survey of the diversity of vascular plants in wetlands was carried out to provide scientific basis for the restoration and protection of wetland ecosystem in Changxing County.  Method  The diversity of vascular plants and the flora in wetlands were studied by route survey and quadrat survey.  Result  (1) There were 464 species of vascular plants, belonging to 277 genera 95 families. Among them, there were 7 species of ferns in 7 genera of 7 families, 4 species of gymnosperms in 3 genera of 2 families, and 453 species of angiosperms in 267 genera of 86 families which included 393 species of dicotyledons in 222 genera of 68 families and 60 species of monocotyledons in 45 genera of 18 families. (2) Families of 2−9 species and 1 species were dominant in the composition of plant families, accounting for 88.42%. Genera consisting of 2−5 species and 1 species were dominant, accounting for 97.11%. (3) Aquatic plants accounted for 82.54% of the total species of wetland plants, and herbaceous plants accounted for 85.86%. (4) There were 11 distribution types of family, dominated by pan-tropic family and north temperate distribution family, in addition to world-wide distribution. There were 12 distribution types of genus, dominated by north temperate distribution genus, and the number ratio of tropical genus to temperate genus was 0.77.  Conclusion  The vascular plants in Changxing County are abundant, and the flora shows typical temperate and transitional characteristics. [Ch, 7 tab. 25 ref.]
Purification effect of immobilized effective microorganism community of fly ash ceramsite on aquaculture wastewater
CHEN Shuang, WANG Liangkai, WEN Tao, MAO Xinyu, XU Ming, SHAO Xiaohou
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190443
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  Objective  With ash and pond sediment as main raw material, the purpose of this research is to prepare biological ceramics with efficient nitrogen and phosphorus removal for treatment of polluted aquaculture water by immobilizing effective microorganism (EM) community.  Method  The optimal proportion of fly ash ceramsite was determined by isothermal adsorption test. The fly ash ceramsite was fixed with EM and treated for 6 days in simulated aquaculture wastewater with ammonia nitrogen, total nitrogen and total phosphorus concentrations of 50, 55 and 20 mg·L−1.  Result  Under the preheating temperature of 300 ℃ and the firing temperature of 1 100 ℃, when the mass ratio of fly ash ceramsite was m (fly ash)∶m (active sediment)∶m (limestone powder)∶m (iron powder)=50∶40∶5∶5, the modified fly ash ceramsite immobilized EM had the best purification effect on nitrogen and phosphorus in the simulated aquaculture wastewater. After 6 days, the maximum removal rates of ammonia nitrogen, total nitrogen and total phosphorus were 99.14%, 92.18% and 44.35%, respectively.  Conclusion  Fly ash ceramsite itself has a certain adsorption and purification capacity of nitrogen and phosphorus. After the immobilization of ceramsite with EM, water purification effect can be enhanced.[Ch, 5 fig. 4 tab. 24 ref.]
Research progress on evolution trends and maintenance measures of soil fertility quality in Cunninghamia lanceolata plantations
GUO Jiahuan, SUN Jiejie, FENG Huili, CAO Penghe, YU Yuanchun
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190478
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In recent years, the growing contradiction between degradation of soil fertility quality and forestry production has seriously threatened the survival and development of human beings. Aiming at the hot issue of degradation and maintenance of soil fertility quality in plantations, this paper systematically elaborates the evolution trend of soil fertility quality in management of Cunninghamia lanceolata plantations from the perspectives of soil physical property, soil chemical property, soil microorganism, soil enzyme activity and allelopathy. Many studies have shown that degradation of soil fertility quality and continuous decrease of productivity are common problems in C. lanceolata plantations, and the main contributing factor is unsustainable forestry practice. The results of soil fertility maintenance in C. lanceolata plantations are reviewed from such aspects as rotation management, mixed compound afforestation, forest density adjustment, fertility compensation and sustainable forest management. The research on soil fertility quality maintenance in C. lanceolata plantations is prospected. [Ch, 1 tab. 48 ref.]
Quality evaluation of Shajiabang National Wetland Park from the perspective of coordinated development
ZHU Ying, WU Yingqian, LI Xin
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190448
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  Objective  The aim is to conduct a scientific assessment of the coordinated development between environmental construction and social service in wetland parks and the overall quality of wetland parks.  Method  Based on the clarification of the quality connotation of wetland parks, this paper, taking Shajiabang National Wetland Park as the research object and applies analytic hierarchy analysis. The quality evaluation indes system of wetland parks is established from the perspective of environmental factors and social services, and the construction of a quality evaluation model as well as a grade classification of wetland parks with the theory of coordinated development degree was introduced.  Result  There has been a significant promotion of the quality grade of Shajiabang National Wetland Park from 2009 to 2018 with arise from Level 1 to Level 4. The coordinated development between environmental construction and social services has been constantly facilitated with the coordinated development index rising from 0.143 to 0.665. Environmental factors such as water quality, invasion of alien species, plant species and bird species affect the quality of wetland parks to a great extent while service factors such as the number of popular science education courses and that of the ecological lecturers are positively correlated to the quality improvementof the wetland parks.  Conclusion  With a higher growth rate than the environmental quality index, the service quality index of wetland parks exerts larger impact on the quality of wetland parks. Therefore, it is advisable that efforts should be focused on the improvement of social service functions so as to effectively promote the overall quality of wetland parks. [Ch, 1 fig. 4 tab. 17 ref.]
Analysis of biomass allocation and allometric growth of Picea schrenkiana in Tianshan Mountains
LAN Jie, XIAO Zhongqi, LI Jimei, ZHANG Yutao
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190384
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  Objective  A proper understanding of the above-ground and underground biomass allocation and carbon storage of Picea schrenkiana, an important tree species in Xinjiang mountainous areas of great significance to the forest resources investigations in Xinjiang. To establish the allometric growth models of trunk, branch, leaf, root, the above-ground part and the whole plant with DBH(D), tree height (H) and DBH-H (D2H, D3/H and DbHc).   Method  Analysis of the of above-ground and underground biomass distribution pattern of 30 P. schrenkiana trees by whole plant harvesting method.  Result  There were significant differences in the biomass of trunk, branch, leaf and root of P. schrenkiana (P<0.01). The biomass of whole P. schrenkiana trees ranged from 12.04−2 014.34 kg·plant−1, and the biomass of the above-ground part and the underground part were 10.16−1 475.17 and 1.88−539.18 kg·plant−1 respectively. The biomass of trunk, branch, leaf and root accounted for 56.86%, 13.03%, 5.96% and 24.15% of the whole plant, and the range of root-shoot ratio was 0.08−0.55. At the plant level, the biomass model of each organ based on DBH(D) and tree height(H) variables was established. The optimal biomass model of root biomass was W=a(D2H)b, and other organs was W=aDbHc. Slope position, slope, altitude and soil thickness are the main environmental factors affecting the biomass of spruce.  Conclusion  The allometric growth model based on tree height (H)-DBH can better fit the biomass of each organ of P. schrenkiana, and can effectively estimate its biomass and carbon reserves. [Ch, 4 fig. 3 tab. 30 ref.]
Community structure characteristics for landscape-recreational forests in the urban parks of Foshan City
ZHAO Qing, HU Rouxuan, XU Dongxian, WEI Yuhan, TANG Honghui
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190396
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  Objective  With an attempt at the clarification of the dominant species and structural characteristics of landscape-recreational forests in different ecological niches, the current paper is aimed to conclude the rules and research the existing problems of the construction of landscape-recreational forests.  Method  With the method of community ecology employed and 20 sample plots in Qiandeng Lake Park, 40 sample plots in Wenhua Park, and 20 sample plots in the Pingzhou Park selected as researching areas, the research was conducted with every tree surveyed using high-resolution remote sensing images. After the diameter classes, height classes and crown areas were clarified, an analysis was made of the differences among different types of landscapes.  Result  (1) Compared with Wenhua Park and Pingzhou Park, Qiandeng Lake Park enjoys a higher level of singleness in tress species with Khaya senegalensis as the dominant tree of large diameter, height, and canopy class; (2) Landscape-recreational forests on closed forest land and besides the buildings are mainly composed of medium-diameter trees while those on in the open forest land and besides the water are mainly composed of small diameter trees with larger diameter trees taking up a small percentage; (3) Landscape-recreational forests in the closed forest land and besides the buildings are mainly composed of the medium-height trees while, those in the open forest land and besides the water are mainly composed of small height trees, with large height trees taking up a small percentage; (4) Landscape-recreational forests are mainly composed of the medium canopy class trees with, the large canopy trees taking up only a small percentage.  Conclusion  To sum up, floristic characteristics of tropical or subtropical monsoon are all shown in the landscape-recreational forests of the three parks. There are differences in the distribution of diameter classes among the trees in the closed forest land and open forest land (the center forest land) as well as those besides the water and buildings (fringe forest land). The differences in the distribution of height class are gradually decreased with the location of landscape-recreational forests shifted from the downtown to subsidiary center and finally to the suburbs. It is necessary to conduct long-term dynamic canopy monitoring to reflect the trend of canopy distribution. [Ch, 3 fig. 4 tab. 20 ref.]
Relationship between height and diameter at breast height(DBH) in mixed coniferous and broadleaved forest based on quantile regression
ZHANG Dongyan, WANG Dongzhi, LI Xiao, GAO Yushan, LI Tianyu, CHEN Jing
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190461
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  Objective  With the employment of nonlinear quantile regression method using dummy variables, the current study is aimed to establish a prediction model for the relationship between height and diameter at breast height (DBH) in Larix principis-rupprechtii and Betula platyphylla mixed forest so as to better predict the tree structure and site productivity of mixed forests.   Method   Taking L. principis-rupprechtii and B. platyphylla mixed forest of Saihanba Mechanised Tree farm in Hebei Province as the research object, with 83 pieces of standard land survey data used and dummy variables created, this paper adopted the least square method and nonlinear quantile regression method respectively in the construction of the relationship model of tree height and DBH of different species.   Result   The accuracy of the nonlinear quantile regression prediction model based on dummy variables was higher than that of the one constructed using the least square method. Specifically, when the least square method was used to fit the tree height and DBH relationship model of different tree species, the determination coefficient, average difference and average absolute error of different tree species models were within the range of 0.787−0.814, 1.581−1.877 and 2.447−2.654 respectively. When the nonlinear quantile regression method was used, the coefficient, average deviation, and average absolute error were within the range of 0.839−0.921, 0.213−1.469, 0.561−2.322. In accordance with the residual analysis, when the quantiles of τ is 0.7, the relationship model of tree height and DBH of different species demonstrated a higher accuracy.   Conclusion   To sum up, compared with the one constructed employing the least square method, the prediction model of tree height and DBH relationship of different tree species adopting the nonlinear quantile regression method has higher prediction accuracy. [Ch, 3 fig. 3 tab. 33 ref.]
Resistance of Phoebe sheareri to anthracnose induced by salicylic acid
HOU Panpan, CHEN Anliang, FEI Libin, MA Liangjin
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190342
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  Objective  The objective is to investigate the resistance of Phoebe sheareri to anthracnose induced by salicylic acid (SA).  Method  The 2-year old P. sheareri was used as material, spayed with 100, 200, 500 mg·L−1 SA. After 5 days, the leaves were collected and in vitro puncture inoculation method was used to determine the inhibition of anthracnose lesions, changes in soluble protein, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in the leaves.  Result  Leaves treated with different concentrations of SA could inhibit the anthracnose lesions, and the lesion inhibition rate with 100 mg·L−1 SA treatment reached 64.28%. After SA spray and inoculation with anthracnose, soluble protein, SOD, CAT and POD in leaves increased in 1−7 days, and decreased after 7 days. At the peak, the soluble protein was 2.57 times of ck, SOD was 1.21 times of ck, CAT was 2.04 times of ck, and POD was 1.46 times of ck. All physiological indexes were higher than those of ck within 15 days.  Conclusion  SA can induce the increase of soluble protein, SOD, CAT and POD of Phoebe sheareri and produce disease resistance.[Ch, 10 fig. 23 ref.]
Analysis of blocking effects of urban roadside forests on PM2.5
LIU Haodong, CHEN Yajing, LI Qingdian, XIAO Mao, GUO Huiling, SHEN Weixing, TAN Yajun, LI Chuanrong
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190335
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  Objective  The present study is to analyze the dynamic change patterns of fine particulate matter (PM2.5) and the blocking effects of urban road forests, and further explore which type of forest belt has the optimal dust and haze control effects.  Method  Three types of urban road forests with a total of 12 configurations were selected. Firstly, the daily dynamics, interannual dynamics and horizontal spatial variations of PM2.5 in and out of the forest belt were analyzed. Then, the dust reduction rate was used to evaluate the blocking effect of different forest belts on PM2.5. Finally, the Pearson correlation analysis was carried out between the dust reduction rate and microclimate factors to explore the possible factors affecting the dust reduction rate of vegetation.  Result  The results showed that concentrations of PM2.5 in roadside forests were highest around 8:00 and 18:00 and lowest at 10:00 and 14:00. The annual dynamic pattern indicated the most obvious change in winter (136.74−194.18 μg·m−3), followed by autumn (63.48−104.96 μg·m−3), spring (28.68−36.31 μg·m−3), and summer (13.30−19.13 μg·m−3). The variation of PM2.5 in the horizontal space of the forest belt varies with seasons. In the spring and summer, PM2.5 gradually decreased from the edge of the forest to the interior of the forest, while in the autumn and winter, the dust margin increased at 25 m in the forest, but decreased at 25−30 m and was lower than the outer edge of the forest. The blocking rate of PM2.5 was highest in arbor-shrub-grass structure, followed by mixed conifer and broadleaved forest structure, and lowest in uniform arbor type. In spring and summer, the blocking rate of 12 kinds of roadside forests on PM2.5 was positive, while in autumn and winter only A5 (mixed conifer and broadleaved forest), B1, B2, and B3 (uniform arbor type) and C2 and C3 (arbor-shrub-grass structure) were positive, and the rest were negative. There were seasonal differences between microclimate factors and PM2.5. PM2.5 concentration was negatively correlated with wind speed in spring, autumn and winter, but positively correlated with relative humidity in autumn and winter, as well as temperature in spring and summer. The block rate of PM2.5 in roadside forests showed a significant positive correlation with temperature in autumn and relative humidity in autumn and winter, but had no significant correlation with other microclimate factors.  Conclusion  The belt width, the proportion of evergreen coniferous trees and shrubs of urban roadside forests should be reasonably increased to reduce PM2.5 and improve air quality. [Ch, 5 fig. 6 tab. 33 ref.]
Effects of shading and fertilization on growth and nitrogen accumulation of Phoebe zhennan seedlings
DENG Bo, YAN Lipeng, LIU Guihua, XU Mengyuan
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190399
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  Objective  This study aims to reveal the effects of shading and fertilization on growth and nitrogen accumulation of Phoebe zhennan seedlings to provide scientific basis for the growth control of this plant.  Method  The two-split-plot test design was used to analyze the effects of shading, fertilization, and interaction of shading and fertilization on the growth, biomass accumulation and nitrogen accumulation of the 1-year-old P. Zhennan seedlings. The main plot contained three different shading levels: natural light (A1, 0% of shading rate), one-layer shading (A2, 54.5% of shading rate), and two-layer shading (A3, 85.3% of shading rate). Each main plot contained three different sub-plots with three different fertilization levels: no fertilization (B1), mild fertilization (B2, 3.3 g compound fertilizer per plant), and moderate fertilization (B3, 6.7 g compound fertilizer per plant). A total of 9 treatments were included in this study.  Result  The growth and nitrogen accumulation were significantly influenced by shading, fertilization, and their interaction (P<0.05). The seedling height, basal diameter, and biomass accumulation under A2B2 treatment were 77.2%, 30.3% and 62.1% higher than those under other treatments, respectively. Furthermore, the nitrogen accumulation reached the maximum under A2B2 treatment, 68.3% higher than that of other treatments. However, the nitrogen content was highest under A3B3 treatment, and was significantly higher than that under other treatments (P<0.05).  Conclusion  Moderate shading and fertilization can increase the nitrogen accumulation, and promote the photosynthesis, growth and biomass accumulation of P. Zhennan, but excessive shading and fertilization can inhibit its growth to some extent. [Ch, 3 fig. 4 tab. 24 ref.]
Characteristics and influencing factors of plant diversity in riverside rural settlement in Guangzhou
WANG Ziyan, WANG Cheng, TANG Sainan, ZHANG Chang, HAN Dan
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190391
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  Objective  This study aims to analyze the horizontal and vertical distribution characteristics of plants diversity in typical riverside rural settlement zones along the Nansha river of Guangzhou, and explore the variation law of plant diversity with the change of the river sections and residential activities.  Method  The basic data were obtained by field survey, satellite image interpretation and mathematical statistics.  Result  A total of 77 species of 70 genera and 44 families were recorded, including 42 species of trees, 19 species of shrubs, 13 species of herbs and 3 species of vines, among which Rosaceae and Palmae had the most species, followed by Moraceae and Rutaceae. There were no significant differences in dominant plant species in different river sections. The dominant trees were Dimocarpus longan, Ficus microphylla and Clausena lansium, while the main shrubs were Osmanthus fragrans, Murraya exotica and Aglaia odorata, and the main herbs were Musa nana and Bambusa textilis. In different reaches from the west gate to the east gate in the study area, tree diversity showed a downward trend as a whole, while no obvious trend was found in shrubs, herbs and overall evenness. However, the diversity and evenness index of trees, shrubs and herbs in the residential section were significantly higher than those in other sections, while the indices in the agricultural section were lower than those in other sections. The river width was significantly correlated with herb diversity, and building coverage was significantly correlated with shrub evenness. Vegetation in the study area was vertically distributed and divided into upper, middle and lower layers with 4 m and 8 m as boundaries. The dominant tree species in different height layers were different. M. nana, B. textilis and D. longan were dominant in the lower layer. D. longan, C. lansium, Taxodium distichum and Gironniera subaequalis were dominant in the middle layer. D. longan, F. concinna and Clausena lansium were dominant in the upper layer.  Conclusion  Human activities have little impact on large trees, but significant impact on small flexible plants such as potted shrubs and herbs. [Ch, 4 fig. 2 tab. 29 ref.]
Characteristics and impact factors of space utilization of young and middle-aged natural Larix gmelinii forests
YU Bao
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190382
[Abstract](306) [HTML](166) [PDF](7)
Abstract:
  Objective  Taking the over-cutting forest in Daxingan mountains as the research object, this study aims to define space utilization of forest, propose the calculation method for space utilization ratio and analyze space utilization law of natural stands from three aspects: horizontal space, vertical space and comprehensive space utilization of stands.  Method  Using the data of 14 sample plots, correlation analysis and stepwise regression analysis were applied to reveal the main factors influencing space utilization ratio of forest stands to provide theoretical basis for the structure optimization of natural stand, its tending and management.  Result  1) The utilization ratios of horizontal space, vertical space and comprehensive space in 14 plots were 62.5%−85.9%, 31.2%−65.5% and 50.1%−68.7%, respectively. The average levels were 73.6%, 46.0% and 59.2%, respectively. 2) With the growth of forest stands, the tree number, individual size and distribution pattern were constantly adjusted, and utilization ratio of horizontal space also changed. The horizontal space utilization ratio of stands was significantly positively correlated with tree number, renewal density as well as tree clustering coefficient (P<0.01), negatively correlated with stand stock (P<0.05) and stand mean breast-height diameter (P<0.01). 3) The vertical space size of stands at different growth stages varied. When stand growth, stand height, tree number and height of each layer were adjusted gradually, the vertical space size and space utilization ratio of forest stands changed dynamically. The utilization ratio of vertical space of stands had extremely significant positive correlation with height of renewal layer (P<0.01), significant negative correlation with tree number, renewal density and forest accumulation coefficient (P<0.05), and extremely significant negative correlation with the number of vertical layer, height of main forest, height of succession, height difference between main forest and renewal layer, height difference between succession layer and renewal layer, and number of plants in renewal layer (P<0.01). 4) The comprehensive space utilization ratio of stands was affected by both horizontal and vertical structure factors, which had significant positive correlation with stand density and plant number of main forest layer (P<0.05), significant negative correlation with vertical layer number and succession height (P<0.05), and extremely significant negative correlation with height of main forest layer, height difference between main forest layer and renewal layer (P<0.01).  Conclusion  Space size and space utilization ratio change dynamically with the growth of forest stands. The main factors affecting utilization of horizontal space, vertical space, and comprehensive space of stands include renewal density, height difference between succession layer and renewal layer, main forest height, stand density and succession height. To improve the utilization ratio of stand space and optimize stand structure, it is necessary to take three-dimensional technical measures that take into account such factors as horizontal and vertical structures. It's also important to reasonably regulate and control the forest stand density in different growth stages, ensure natural renewal capability of forest stands, and reasonably set the tree number and height distribution at all levels of stands to form a stepped distribution state and make full use of stand space. [Ch, 6 tab. 22 ref.]
Correlation between the remote sensing index of the underlying surface and the surface temperature in the villages in Hangzhou
JIN Jiale, SUN Jian, YANG Libin, DONG Chengfeng, QI Feng
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190379
[Abstract](237) [HTML](113) [PDF](12)
Abstract:
  Objective  In order to figure out how the underlying surface influences the thermal environment of villages and towns, the current study is aimed at a further analysis of the correlation between the characteristics of the underlying surface and the surface temperature of various villages and towns.  Method  First, single-channel algorithm was used to invert the underlying surface temperature of villages and towns. Then, based on the the features of different wave bands of remote sensing data, the normalized difference vegetation index (NDVI), normalized difference build-up index(NDBI), normalized difference impervious surface index(NDISI), normalized difference moisture index(NDMI) and modified normalized difference water index(MNDWI) were calculated. Lastly, on the basis of the results of surface temperature and remote sensing index in summer and winter in Hangzhou, a statistic analysis was conducted of the linear correlation between the characteristics of the underlying surface and the surface temperature of different types of villages and towns.  Result  The land surface temperature had a significant negative correlation with NDVI and NDMI; but a significant positive correlation with NDBI. The influence of NDMI and NDBI on surface temperature was greater than that of NDVI index, while the influence of NDISI and MNDWI on surface temperature was relatively weaker. The correlation between land surface temperature and surface remote sensing index in winter was weaker than in summer.  Conclusion  Reducing the building density, improving the underlying surface humidity and increasing vegetation coverage were all conducive to the reduction of the surface temperature of villages and towns in summer and the optimization of the thermal environment of villages and towns. [Ch, 7 fig. 2 tab. 27 ref.]
Automatic navigation of production platform in greenhouse based on wireless positioning
ZHAO Chenyan, YAO Lijian, YANG Zidong, YAN Song, CAI Cuncheng
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190364
[Abstract](106) [HTML](64) [PDF](14)
Abstract:
  Objective  The current paper is aimed to put forward a path tracking method based on ultra wideband (UWB) positioning and fuzzy control with self-adjustment function in order to improve the accuracy of automatic vehicle navigation in greenhouse.  Method  Firstly, the UWB module was used to construct the wireless positioning system, with which the positioning error of the experimental data was fitted employing bivariate cubic polynomial while measurement point errors were corrected by means of data fitting. Secondly, the weight of lateral deviation and heading deviation was dynamically adjusted with a self-adjusting analytic fuzzy controller so as to obtain the front wheel angle. Finally, real vehicle tests of linear and rectangular path tracking were carried out with the results compared with those obtained employing pure tracking method.  Result  When the line path tracking with different initial stages is conducted, there was an average deviation of 22.4 cm, a standard deviation of 5.8 cm and a mean steady-state deviation of 5.4 cm. And the accuracy of this model has been improved by 28.4%, 40.2% and 34.9% respectively compared with that of pure tracking model. As for rectangular path tracking, the average deviation of the current method is 14.4 cm and the maximum deviation is 46.9 cm, with the maximum deviation mainly occurring at the corner of the rectangle. Similarly, the accuracy of this model is improved by 46.5% and 53.5% respectively, compared with that of the pure tracking model.  Conclusion  The method presented in this paper demonstrates favorable stability and control precision, and it could meet the needs of the automatic navigation operation of the production platform in the greenhouse. [Ch, 8 fig. 3 tab. 24 ref.]
Impact assessment of fuel regulation measures in Platycladus orientalis forest in Western Hills of Beijing
LI Weike, ZHANG Chen, GU Xinghan, NIU Shukui, YIN Jiyan, LIU Xiaodong
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190343
[Abstract](102) [HTML](48) [PDF](7)
Abstract:
  Objective  Based on the fuel distribution characteristics of the Platycladus orientalis forest in Western Hills of Beijing, fuel regulation measures of different intensities were implemented, and effects of the fuel regulation measures were evaluated according to the biodiversity and photosynthetic characteristics of understory vegetation.  Method  P. orientalis, a typical coniferous tree species in North China was selected as the research object. By investigating and analyzing distribution characteristics of P. orientalis forest fuel, regulation measures focusing on pruning, cutting and irrigation were formulated, including: unregulated stands (ck), pruning height 2.5 m and cleaning the surface litter appropriately (P1), pruning height 3.0 m and cutting shrubs and cleaning the surface litter appropriately (P2), pruning height 3.5 m and cutting shrubs and cleaning the surface litter appropriately (P3). Three sample plots of 20 m×20 m were established for each treatment, and changes of plant diversity and photosynthesis attributes of dominant shrubs were compared between regulated and unregulated stands.  Result  The biodiversity of understory vegetation was altered after different fuel managements, among which the species dominance (D) and diversity (H) of shrub layer and grass layer and the species evenness (J) of shrub layer after P2 management were significantly higher than those of ck. Compared with ck, the maximum net photosynthetic rate, light saturation point, light compensation point, dark respiration rate of the understory vegetation (Grewia biloba var. parviflora and Broussonetia papyrifera) all increased, while the apparent quantum efficiency decresed after P2 management. We observed that the accumulation of understory vegetation photosynthetic products was more obvious with P2 management.  Conclusion  The implementation of regulation measures changed the forest structure and increased the light intensity. The effects of different regulation intensity on biodiversity and photosynthetic characteristics of understory vegetation were different. P2 management was most conducive to stand recovery in the study area. [Ch, 2 fig. 4 tab. 26 ref.]
Extraction of polysaccharides of Abelmoschus esculentus using ultrasonic-assisted [Bmim] Cl-K2HPO4 aqueous two phases optimized by response surface method
HE Ziqiang, ZHANG Huiling, YANG Zhengxiong
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190339
[Abstract](92) [HTML](49) [PDF](4)
Abstract:
  Objective  This study attempts to explore the optimum technology of ultrasonic-assisted [Bmim]Cl-K2HPO4 extraction of okra polysaccharides.  Method  Cloud point titration was used to compare the phase separation ability and extraction ability of four aqueous two-phase systems, [Bmim]Cl-(NH4)2SO4, [Bmim]Cl-Na2HPO4, [Bmim]Cl-Na2CO3 and [Bmim]Cl-K2HPO4. [Bmim]Cl-K2HPO4 was determined to be the best aqueous two-phase system. The polysaccharides were extracted from okra (Abelmoschus esculentus) by ultrasonic-assisted [Bmim]Cl-K2HPO4. The effects of five single factors on the extraction rate were discussed: mass fraction of K2HPO4, extraction time, extraction temperature, liquid-solid ratio and mass fraction of [Bmim]Cl. On the basis of the optimum conditions of each single factor experiment, the Box-Behnken design of response surface was applied to optimize the extraction process of okra polysaccharides.  Result  The results showed that the effects of various factors on the extraction rate ranging from large to small included liquid-solid ratio, mass fraction of [Bmim]Cl, extraction temperature, extraction time, and mass fraction of K2HPO4. The optimum extraction conditions were aqueous two-phase system consisting of 5 mL ionic liquid [Bmim]Cl with mass fraction of 71.94%, and 5mL K2HPO4 with mass fraction of 22.31%, extraction time of 29.36 min, extraction temperature of 55.69 ℃, and liquid-solid ratio of 25.00 mL·g−1. Under the above optimized extraction conditions, the predicted value of extraction rate was 29.12%. The validation average was 31.22%, and RSD was 3.70%.   Conclusion  Ultrasonic-assisted extraction of [Bmim] Cl-K2HPO4 has such advantages as high extraction rate, short time and recyclable ionic liquids, and can be used in industrial production. [Ch, 8 fig. 3 tab. 24 ref.]
Effects of exogenous oxalic acid on antioxidant enzymes and lignification of Bambusa oldhami shoots
YU Tun, ZHENG Jian, YU Xuejun
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190337
[Abstract](220) [HTML](121) [PDF](15)
Abstract:
  Objective  The purpose is to explore the preservation effect and mechanism of exogenous oxalic acid treatment on bamboo(Bambusa oldhami) shoots at low temperature.  Method  The peeled bamboo shoots were soaked in 5 mmol·L−1 oxalic acid solution for 10 minutes and stored at 6±1 ℃. The effects of oxalic acid treatment on H2O2 content, SOD activity, CAT activity, hardness, lignin content, key enzymes of lignin metabolism (PAL, 4-CL, CAD, POD) activities as well as their gene expression levels were measured regularly.  Result  Soaking the bamboo shoots in 5 mmol·L−1 oxalic acid solution for 10 minutes increased the activities of SOD and CAT, delayed the accumulation of H2O2, inhibited the increase of key enzymes of lignin metabolism (PAL, 4-CL, CAD, POD) activities and their gene expression level, and significantly reduced the accumulation of lignin and hardness increase in bamboo shoots without sheaths.  Conclusion  Exogenous oxalic acid treatment can retard the lignification process in bamboo shoots without sheaths by inhibiting lignin metabolism and improving antioxidant enzyme system. Thus, the quality decline during the cold storage could be postponed. [Ch, 4 fig. 32 ref.]
Imaging ules in chlorophyll fluorescence of soybean pods in response to Fusarium verticillioides
LONG Xiyang, XIAO Xinli, ZHANG Qihui, YANG Wenyu, LIU Jiang, ZHANG Jing
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190325
[Abstract](133) [HTML](91) [PDF](11)
Abstract:
  Objective  The current study, in order to establish the index for the rapid identification of the resistance of soybean pods, is focused on three cultivars of cultivars, namely the high-resistant cultivar ‘QWT15-2’, the medium-resistant cultivar ‘E1’ and the sensitive cultivar ‘E314’.  Method  The pods were first inoculated with Fusarium verticillioides in vitro, and then the changes of chlorophyll fluorescence parameters in pods were monitored with the employment of chlorophyll fluorescence imaging technology.  Result  After 24 hours of inoculation, the epidermal lesions of the pods were clearly observed through the chlorophyll fluorescence imaging system, and there was a significant change in the fluorescence parameters. To be specific, 0−5 days after mold infection, there was a significant decrease in the initial fluorescence parameters Fo, Fm, Fv of soybean pods, an increase in the non-photochemical quenching coefficient qN and a decrease in QNP, which was accompanied with an inclination of decline in the maximum photochemical efficiency Fv/Fm, actual photochemical efficiency ΦPSⅡ and electron transport rate RET.  Conclusion  The high-resistant culivar ‘QWT15-2’ maintained a relatively healthy tissue with stable fluorescence parameters. The medium-resistant cultivar ‘E1’ and the sensitive cultivar ‘E314’ were affected by mold infection with severe epidermal tissue damage and significant change in the fluorescence parameters. Fluorescence parameters such as Fv/Fm, Fm, Fv, qN and QNP are sensitive to mold infection and can be used as an indicator to evaluate the resistance of soybean pods in the field. [Ch, 4 fig. 17 ref.]
Forests landscape pattern changes and driving forces in Mount Tianmu
YU Fei, LI Zhiyong
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190306
[Abstract](131) [HTML](83) [PDF](16)
Abstract:
  Objective  This research studied the characteristics and driving forces of landscape pattern change in southern collective forest area to provide scientific basis for sustainable forest management.  Method  Landscape pattern change characteristics of state-owned forest in Zhejiang Tianmu Mount nature reserve and collective forest in surrounding community of the reserve in 2000, 2010 and 2017 were compared and studied by using landscape type area transfer matrix and landscape pattern index analysis method.  Result  Ecological forest was the dominant landscape in the reserve and communities. The area of ecological forest increased in the reserve and decreased in the communities, while the area of economic forest changed in an opposite way. The bamboo forest and hickory forest transformed to ecological forest in the reserve, while ecological forest transformed to economic forest, buildings and roads, then mutual transformation between different kinds of economic forest or mutual transformation between economic forest and cultivated land in the communities. The landscape pattern in the reserve changed little, but landscape fragmentation, heterogeneity and uniformity in the communities increased year by year, and the ascendancy of ecological forest had been on the decline. Policy factors, market demand changes and roads were the main driving forces behind the changes of forest landscape patterns.  Conclusion  Changes of landscape patterns in community may affect ecological and cultural functions of forest. Measures, such as policy making, tourism development and road construction can be taken. [Ch, 1 fig. 8 tab. 17 ref.]
Effects of wetland reclamation on kinetic characteristics of soil alkaline phosphatase
XU Chuanhong, LU Mingxing, FAN Diwu, CHENG Hu, HAN Jiangang
Accepted Manuscript doi: 10.11833/j.issn.2095-0756.20190388
[Abstract](89) [HTML](49) [PDF](6)
Abstract:
  Objective  Enzyme kinetics study is a crucial method to reveal nutrient transformation in soil. The purpose of this study is to investigate the effects of wetland reclamation on transformation and availability of soil phosphorus and provide theoretical basis for nutrient conversion efficiency and quality improvement of wetland.  Method  Eight kinds of soil with different natural covers or land use patterns were collected in Hung-tse Lake estuary (shoal, Phragmites communis, Populus and paddy field) and Chongming Dongtan wetlands (shoal, Spartina alterniflora, P. communis and wheat field), and the soil alkaline phosphatase (ALP) was taken as an example to study kinetic characteristics of enzymatic reaction. One-Way ANOVA was used to compare the difference of soil ALP dynamic parameters under different land uses, and the correlation between physical and chemical properties of soil and kinetic parameters was explored by using redundancy analysis.  Result  Vmax (maximum reaction rate) and Km (Michaelis constant) of ALP kinetic parameters increased by 13.0%−313.4% and 21.0%−50.8%, respectively in Hung-tse Lake wetland, no matter whether the shoal naturally evolved into P. communis, or the reclaimed P. communis wetland into Populus plantation or paddy field. However, the Vmax/Km (catalytic efficiency) decreased by 25.0% during natural succession and increased by 2.3 times after artificial reclamation. For Chongming Dongtan wetland, Vmax and Km increased by 7.0 times and 6.2 times, and Vmax/Km increased by 11.1% after the transformation of shoal into P. communis. Moreover, the Vmax, Km and Vmax/Km decreased by 54.8%, 47.0% and 13.3% respectively after the conversion of P. communis into wheat field. Redundancy analysis results indicated that the Vmax/Km was positively correlated with total nitrogen (Hung-tse Lake) and organic carbon (Chongming Dongtan).  Conclusion  The total ALP significantly increased when the shoal was transformed into P. communis wetland, but the affinity between enzyme and substrate decreased. The Vmax/Km of ALP was significantly influenced by land use type and management mode after artificial reclamation. Increasing soil total nitrogen and organic carbon is beneficial to improvement of ALP catalytic efficiency no matter whether the land type is natural cover or artificial reclamation. [Ch, 1 fig. 3 tab. 43 ref.]
MaxEnt model-based prediction of potential distribution of Liriodendron chinense in China
QIU Haojie, SUN Jiejie, XU Da, SHEN Aihua, JIANG Bo, YUAN Weigao, LI Sheng
2020, 37(1): 1-8.   doi: 10.11833/j.issn.2095-0756.2020.01.001
[Abstract](40) [HTML](21) [PDF](5)
Abstract:
  Objective  The aim is to scientifically and rationally develop protective measures for Liriodendron chinense.  Method  Maximum Entropy Model (MaxEnt) and Geographic Information System (ArcGIS)were adopted to predict the potential distribution areas of L. chinense, and to explore the dominant environmental factors of L. chinense under various climate change scenarios.  Result  The mean AUC of the training data was 0.973, and the AUC of the test data reached 0.953, indicating that MaxEnt model had a good predicting ability. The annual precipitation, precipitation of wettest quarter, min temperature of coldest month, precipitation of seasonality and monthly mean temperature difference were predicted to be five main factors affecting the distribution of L. chinense, with a total contribution rate of over 80%. The intensity of human activities was 2.3%. Then MaxEnt model was imported into GIS to classify the suitable areas, and the results showed that the highly suitable distribution areas of L. chinense ranged from south of Daba Mountain to the north-central part of Guizhou in Southwest China; its southernmost part extended to the hilly area in the southern part of Zhejiang Province and the northern part of Fujian Province while its northernmost part reached the Tianmu Mountain in East China, which was similar with the investigation before. Meanwhile, the distribution of L. chinense in China under different RCP scenarios of the 2050s and 2070s was simulated. The study showed that the potential distribution area would move to higher latitudes, and the area would remain stable and then decline with the growth of the year. In 2070s under the climate scenario of RCP 8.5, the distribution area of L. chinense would decrease by 5.3% compared with the current period. These were consistent with the results of previous studies on the reduction of biogenic suitable area in the context of global warming.  Conclusion  The predictions indicated that climate change would affect the distribution of L. chinense populations, and would provide a reference for the future cultivation and ex-situ conservation of L. chinense too.
Dynamic evolution and landscape ecological risks assessment of Qilu Lake in Yunnan Plateau
WANG Tao, XIAO Caixia, LIU Jiao, LU Xin
2020, 37(1): 9-17.   doi: 10.11833/j.issn.2095-0756.2020.01.002
[Abstract](38) [HTML](12) [PDF](0)
Abstract:
  Objective  The research aim is to study the dynamic evolution process of Qilu Lake and its watershed landscape ecological risks under the background of climate change.  Method  The lake boundary was extracted based on eight time series Landsat images from 1975 to 2015, and three watershed landscape classification data were interpreted. The dynamic evolution of Qilu Lake was studied from the change of lake area, lake shape and the lake centroid. The ecological risk assessment model was established by dividing ecological risk sampling plots, and the landscape ecological risk of Qilu Lake Basin was quantitatively analyzed.  Result  (1) Over the last 30 years, the landscape structure of Qilu Lake Basin has changed obviously; the area of construction land and beach wetland has increased significantly; the area of farmland, forest land and water area has decreased continuously, and the area of unused land has not changed much; (2) Over the last 40 years, Qilu Lake has been in a continuous shrinking state, and the water area in 2015 is only 56.05% of that in the largest year (1985); Qilu Lake is characterized by continuous and complex changes in shape, the most obvious change is at the entrance of rivers to lake in the west and south part, and the smallest change in the east part; The centroid of Qilu Lake mainly migrates to the northeast, and there is a 1 242 m gap between the centroid in 1975 and that in 2015. The results of ecological risk assessment indicates that the main ecological risk is in lower grade, accounting for 26.75%-35.09% between 1985-2015; The average ecological risk has increased from 0.957 8 to 1.013 9 between 1985-2015, indicating increasing ecological risks.  Conclusion  The spatial distribution of ecological risk in Qilu Lake Basin has obvious aggregation and spatial heterogeneity. The high ecological risk mainly lies in the Qilu Lake, the low ecological risk mainly in the lake basin, and the other ecological risks mainly in block or band along the lake basin and lake.
Characteristics of litter-root-soil ecological stoichiometry of three forest stands in northern Guangdong
LI Feifan, SUN Bing, PEI Nancai, YAN Weiming, LUO Xinhua
2020, 37(1): 18-26.   doi: 10.11833/j.issn.2095-0756.2020.01.003
[Abstract](29) [HTML](14) [PDF](1)
Abstract:
  Objective  The similarities, differences and inducements of nutrient distribution between plantation and secondary forest were analyzed, in order to master the situation and dynamic law of nutrients in different parts.  Method  The leaves, roots and soil (0-20 cm) of the Castanopsis hystrix plantation(CHP), the Michelin chapensis plantation(MCP) and the secondary forest(SF) were investigated in the southern subtropical region of northern Guangdong. Total C, total N and total P concentrations of litter, roots and soil were measured.  Result  (1) There was no significant difference in the concentrations of C and P in the litter among the three stands (P>0.05), but the concentrations of litter N in the CHP were significantly higher than those in MCP and the secondary forest. The roots of C, N and P concentrations were significantly different among the three stands (P < 0.05) and both N and P concentrations were MCP > SF > CHP. The C, N, and P concentrations in the soil were significantly different and both were CHP > SF > MCP. (2) All the three stands showed a C/N ratios of roots > litter > soil; while CSP and the secondary forest showed a C/P ratios of roots > litter > soil. C/P ratios was litter > root > soil in the MCP. N/P ratios was litter > root > soil in the three stands. C/N, C/P, and N/P ratios were not significantly different among the three types of forests; C/N and C/P ratios of litter were highest in MCP. All C/N and C/P ratios of roots were CHP > SF > MCP. (3) The N and P concentrations of roots in CSP, the N and P concentrations of litter and roots in MCP and the secondary forest displayed a significantly positive correlation (P < 0.05). There was no correlation between C/N and N/P ratios in litter and roots of the three stands (P>0.05). There was a significant positive correlation between C/P and N/P ratios in litter, roots and soil of CHP and MCP (P < 0.05), while C/P and N/P ratios of the secondary forest only showed a significant positive correlation (P < 0.05) between litter and soil.  Conclusion  Roots of different stands displayed different laws of soil nutrient absorption. Compared with the national average value of soil nutrients, the study area showed a pattern of high N and low P, indicating that local soil was limited by P. Therefore, P can be appropriately applied according to demand to improve soil nutrient quality.
Reconstruction measures of species diversity of low-function Platycladus orientalis forest in Beijing
JIN Mengli, HU Jun, QI Shi, LU Jinsheng, LI Yue, JIANG Jiuhua
2020, 37(1): 27-35.   doi: 10.11833/j.issn.2095-0756.2020.01.004
[Abstract](46) [HTML](11) [PDF](1)
Abstract:
  Objective  One of the main tasks of reconstruction of low-function forest of Beijing-Tianjin Sandstorm Source Control Ⅱ Project is to increase species diversity indices. The aim is to explore and assess the effects of various environmental factors on the species diversity indices of understory in low-function forests in Beijing.  Method  35 low-function Platycladus orientalis forest plots were investigated and species diversity indices were also calculated. The Maximum Entropy model was used to study the relationship between 10 environmental variables (such as soil properties and topographic factors) and understory species diversity indices of low-function cypress forests, analyze the effects of site conditions on understory biodiversity of cypress forest.  Result  (1) The main environmental variables affecting the species diversity indices were altitude, slope direction, soil total phosphorus content, slope and soil total potassium content, and the cumulative contribution rate of the five indices reached 93.8%; (2) The probability higher than filter value of species diversity under low-function cypress forests increased from 0.354 to 0.431, 0.654 and 0.379 by improving soil total phosphorus, total potassium content and micro-topography, and the distribution probability was increased to 0.738 after implementing the above three measures. The total phosphorus, total potassium content of soil in classes of low-function cypress forest and slope measures adopted separately and simultaneously can help improve diversity.  Conclusion  Improvement of site conditions can increase the species diversity indices of low-function cypress forest.
Plant community characteristics of young Cunninghamia lanceolata sprout forest
TIAN Tian, YU Shuquan, ZHANG Xudong, BAI Yanfeng, ZHANG Huafeng, JIANG Chunqian
2020, 37(1): 36-42.   doi: 10.11833/j.issn.2095-0756.2020.01.005
[Abstract](35) [HTML](12) [PDF](2)
Abstract:
  Objective  This study aims to explore the way of forest rehabilitation, improve the forest structure, maintain biodiversity and provide a reference for further research on plant community characteristics of Cunninghamia lanceolata forests.  Method  A field investigation was conducted on the plant community characteristics of the second generation young C. lanceolata sprout forest in Xikou Village, Lin'an, Zhejiang Province in October 2017.  Result  The data analysis showed that there were 104 species of plants in the young C. lanceolata sprout forest in Xikou Village, including 14 species of arbor layer plants, 58 species of shrub layer plants, and 41 species of herbaceous layer plants. The dominant vegetation constituted the C. lanceolata-Rubus hirsutus-Pteridium aquilinum community. The species richness index, the Simpson index, the Shannon-Wiener index, and the Pielou index were all shrub layer > herbal layer > tree layer. Except for some dominant species, most plant species of understory vegetation were small in number and sparsely distributed.  Conclusion  It is recommended that needs of local farmers and communities should be taken into consideration to improve the heterogeneity of forest ecosystem species, structure and resource use, and local native broad-leaved tree species and suitable broad-leaved tree species should be selected for replanting to form mixed forests, supplemented by scientific cultivation measures.
Analysis of PeATG1/PeATG4 gene expression in Phyllostachys edulis during rapid growth
BU Keli, FU Lucheng, WANG Lingjie, LI Qingli, WANG Keyang, MA Yuandan, GAO Yan, ZHANG Rumin
2020, 37(1): 43-50.   doi: 10.11833/j.issn.2095-0756.2020.01.006
[Abstract](33) [HTML](17) [PDF](1)
Abstract:
  Objective  The aim is to discuss the relationship between rapid growth of stems of Phyllostachys edulis and gene expression of PeATG1 and PeATG4.  Method  Stems of P. edulis shoots were used as materials, the autophagic activity at different periods (10:00, 14:00, 18:00, 22:00, 2:00, and 6:00) and in different parts (internodes 4, 7, 10 and 13) was monitored by transmission electron microscope (TEM), and the expression of PeATG1 and PeATG4 genes in the 7th internode was determined by real-time fluorescence quantitative polymerase chain reaction (qRT-PCR).  Result  The autophagosomes were observed at 22:00 and 2:00 in internodes 7 and 10 during 24 h monitoring, while no autophagosome was observed in internodes 4 or 13. The expression of PeATG1 and PeATG4 enhanced at night. The expression of PeATG1 was highest at 22:00, which was 3.0-fold and 1.3-fold of 18:00 and 6:00 respectively (P < 0.05). The expression of PeATG4 was highest at 2:00, which was 1.7-fold and 1.6-fold of 18:00 and 6:00 respectively (P < 0.05).  Conclusion  The research showed significant differences in growth and development of P. edulis at different stages. Autophagosomes were formed at night, and the expressions of PeATG1 and PeATG4 were high, which resulted in rapid growth of stems.
Effects of bamboo shoot truncation on growth and chlorophyll fluorescence characteristics of Dendrocalamopsis oldhami
LU Yusheng, GUAN Fengying, PENG Chao, YIN Zixu, ZHANG Meiman, ZHAN Meichun, YAN Yingjie
2020, 37(1): 51-59.   doi: 10.11833/j.issn.2095-0756.2020.01.007
[Abstract](46) [HTML](27) [PDF](2)
Abstract:
  Objective  The aim is to explore the dwarf method and clarify preliminarily the growth and photosynthetic mechanism of Dendrocalamus oldhami, effects of bamboo shoot truncation on morphology, survival rate, chlorophyll content and chlorophyll fluorescence parameters of D. oldhami.  Method  Different heights H1(60 cm), H2(90 cm), H3(120 cm), H4(150 cm), H5(180 cm) of bamboo shoots at peak period in Youxi County, Fujian Province were used as test materials and bamboo shoots without truncation as the control group.  Result  (1) Morphological characteristics changed significantly after bamboo shoot truncation treatment, and there was a significant negative correlation between plant height and bamboo shoot height before truncation (R2=0.90, P < 0.01). Plant height of H5 after treatment was 539.40 cm and that of the control group was 234.70 cm, reducing by 56.49%. With bamboo shoot truncation treatment, the under branch height, internode number and branch rate decreased significantly while the length of the main branch increased. Survival rate of D. oldhami ranged from 82.14% to 85.71%, and no significant difference in survival rate was observed (P>0.05).(2) The chlorophyll a, chlorophyll b and total chlorophyll of D. oldhami increased while chlorophyll a/b decreased. (3) There was no significant difference in initial fluorescence (Fo) between the experiment groups and the control group. With the decrease of plant height, the PS Ⅱ maximal photochemical efficiency(Fv/Fm) and photochemical quenching coefficient (qP) enhanced, while the nonphotochemical quenching coefficient (qNP) reduced. The maximum values of electron transport rate (ETR) and PS Ⅱ actual photochemical efficiency(Yield) were achieved under H5 treatment, increasing by 48.63% and 42.17% respectively compared with the control group. (4) Pearson correlation analysis showed that plant height was negatively correlated with total chlorophyll and chlorophyll fluorescence parameters Fv/Fm, Yield and ETR, and positively correlated with chlorophyll a/b and qNP.  Conclusion  It could be concluded that 180 cm was the optimal bamboo shoot truncation treatment, which helped control plant height and improve photochemical effect.
Seed germination and seedling growth response to drought stress and resistance evaluation for introduced Pinus sylvestris var. mongolica sandy-fixation plantation
WANG Dongli, ZHANG Risheng, FANG Xiang, WANG Kai, WU Yeli, QIN Songyue, LONG Dandan, SHEN Haiou
2020, 37(1): 60-68.   doi: 10.11833/j.issn.2095-0756.2020.01.008
[Abstract](34) [HTML](14) [PDF](1)
Abstract:
  Objective  The aim is to understand the difficulty of seedling breeding and to solve the natrual regeneration problem in declined stands of Pinus sylvestris var. mongolica sandy-fixation plantation, response characteristics of the seed germination and seedling growth as well as resistance to drought stress were mined.  Method  An indoor control method was used for drought stress, with PEG 6000 (polyethylene glycol) solution concentrations (in MPa) and treatments being 0 (ck), -0.054 (T1), -0.177 (T2), -0.393 (T3), and -0.735 (T4). Seeds of P. sylvestris var. mongolica for different stand ages from the south margin of Horqin Sandy Land were selected as study materials, with characteristics of seed germination and seedling growth were measured. Drought resistance of P. sylvestris var. mongolica were analyzed by using principal component analysis and membership function method.  Result  Seed germination percentages and seed germination rates declined with an increase in time before germination in drought stress. Seed germination duration shortened significantly for T4 (P < 0.05). Differences existed between stand ages and responses of seed germination characteristics to drought stress. With strong drought stress, seed duration was extended for younger forests, but seeds of older forests finished germination rapidly. The threshold value of response to drought stress for seed germination percentage of 28 year-old P. sylvestris var. mongolica was maximal. Seedling growth relative value declined with drought stress and increased firstly then decreased as drought stress increased. Embryo length and hypocotyl diameter decreased overall as drought stress increased, and radicle length increased with drought stress. The membership function method showed that drought tolerance for different forest ages for P. sylvestris var. mongolica was in the order of 16 a > 28 a > 35 a > 54 a. Responses to drought stress during the germination stage included reduction in germination percentage, delayed germination, extended duration of germination time, slowed seed germination rate and increased radicle growth.  Conclusion  Drought tolerance of P. sylvestris var. mongolica during seed germination stage decreased as stand age increased, making it suitable to select seeds during the early production stage to promote natural regeneration of P. sylvestris var. mongolica sandy-fixation plantation.
Soil oxygen content of Phyllostachys violascens with pipe-buried aeration
GUO Yichang, ZHUANG Shunyao, HU Yuyan, GUI Renyi
2020, 37(1): 69-75.   doi: 10.11833/j.issn.2095-0756.2020.01.009
[Abstract](46) [HTML](10) [PDF](1)
Abstract:
  Objective  Limitations to growth and biomass production are expected due to low soil oxygen content. To increase soil oxygen content of Phyllostachys violascens stands under various managements and to provide a new technique for soil aeration and sustainable management of P. violascens are necessary.  Method  A pipe-buried aeration method was adopted. An in-situ measurement was used to detect soil oxygen content of various managed bamboo stands. There are split-plot design with four treatments (M:mulching without aeration, MA:mulching with aeration, A:no mulching with aeration, and ck:no mulching without aeration) and 3 replications. We studied the response of soil oxygen content after pipe-buried aeration to four levels of soil depth(V10, V20, V30 and V40, respectively)and four levels of distance to pipe(H15, H30, H45 and H60, respectively).  Result  The mulching technique could lead to soil hypoxia, but the pipe-buried aeration improved soil oxygen significantly(P < 0.05). In the soil layer below 40 cm, soil oxygen content increased 2.20%-5.25% compared to the control(P < 0.05). For the vertical level in various layers, soil oxygen content increased 0.78%-4.98%(P < 0.05). When the mulching technique was adopted, the pipe-buried aeration method increased soil oxygen content 1.26%-4.71%(P < 0.05). When water saturated, the aeration method increased soil oxygen content 0.69%-7.58%(P < 0.05).  Conclusion  The pipe-buried aeration method was an effective measure for increasing bamboo soil oxygen content, and it could be promising with sustainable bamboo management.
Response of soil microorganism to stand density in Cunninghamia lanceolata plantation
LI Zhichao, ZHANG Yongqiang, HOU Lingyu, SONG Liguo, SUN Qiwu
2020, 37(1): 76-84.   doi: 10.11833/j.issn.2095-0756.2020.01.010
[Abstract](39) [HTML](14) [PDF](0)
Abstract:
  Objective  To provide theoretical basis for the sustainable development of Cunninghamia lanceolata public welfare forest, a study is conducted of the response of soil microbial carbon metabolism to stand density and the relationship between soil physico-chemical properties and microbial carbon metabolism.  Method  With the Biolog-ECO method employed, five 38-year-old C. lanceolata plantations with various densities were selected in Dagang mountain to study the functional diversity of carbon-source metabolism.  Result  (1) When the survival density of C. lanceolata was 2 600-4 600 plants·hm-2, the average color change rate (AWCD) which is reflective of the diversity of soil microbial metabolic function was higher and such density range comes with a high soil microbial diversity, which contributes to the soil organic matter decomposition and soil nutrients' transformation and accumulation. (2) The utilization amount of six carbon sources by soil microorganisms varies for C. lanceolata plantations of different densities. When the density was 2 600-4 600 plants·hm-2, the main carbon sources were carbohydrates, followed by carboxylic acids and amino acids. When the density was lower or higher, the soil microorganisms utilized more carboxylic acids than carbohydrates. It is shown in the principal component analysis that α-D-lactose contributed the greatest to the utilization of soil microorganisms and was the most utilized substance in C. lanceolata plantation. It is demonstrated in the correlation analysis that the total nitrogen and alkali-hydrolyzable nitrogen were significantly correlated with microbial diversity, and were the decisive factors for microbial carbon utilization.  Conclusion  With both the microbial carbon metabolism and soil physico-chemical properties taken into consideration, it was found that the density of 2 600 plants·hm-2 was the most suitable for the sustainable development of C. lanceolata plantation.
Effects of different rice straw returning quantities on soil fauna community structure
LUO Manli, DUAN Junhua, YAO Heng, LU Changtai, XIAO Jiujin, ZHANG Jian
2020, 37(1): 85-92.   doi: 10.11833/j.issn.2095-0756.2020.01.011
[Abstract](36) [HTML](17) [PDF](0)
Abstract:
  Objective  The aim is to reveal the effects of different straw returning quantities on cropland soil fauna community.  Method  An experiment with four types of straw returning quantities[0.8(T20), 0.4(T10), 0.2(T5) kg·m-2 and no straw returning(ck)], were carried out in 5 m×5 m quadrats. Hand-picking method and dry and wet funnel separation method were used in the experiment.  Result  The total soil animals 1 194 were captured in this survey, belonging to 3 phyla, 11 classes, 19 orders and 44 families. The average density of soil animals was 4.45×105 ind·m-2. The density and variety of soil animals in the sample land increased significantly after straw returning(P < 0.05). The varieties were ranked as follows:T20(37) > T10(30) > T5(28) > ck(17). The vertical distribution of soil fauna community was obvious, and the density of soil fauna decreased with the deepening of soil layer, which had obvious surface aggregation. Two months after straw returning, T20 had the highest diversity index, evenness index and species richness. Five months after straw returning, T10 had the highest predominant index.  Conclusion  0.8 kg·m-2 straw returning quantity is suggested.
A catastrophe model to forecast larvae occurrence of Dendrolimus punctatus
ZHANG Shuping, YU Yan, BI Shoudong, ZHOU Xiazhi, ZOU Yunding, ZHANG Guoqing, ZHANG Zhen, FANG Guofei, SONG Yushuang
2020, 37(1): 93-99.   doi: 10.11833/j.issn.2095-0756.2020.01.012
[Abstract](31) [HTML](14) [PDF](0)
Abstract:
  Objective  The aim is to improve control of Dendrolimus punctatus larval occurrence, and to select a suitable prediction model by increasing prediction accuracy through a catastrophe prediction method.  Method  The prediction model GM(1, 1) for D. punctatus was used over 28 years from 1989 to 2016 in Qianshan County, Anhui Province.  Result  The GM(1, 1) cataclysmic prediction model for the overwintering generation of D. punctatus was as follows:\begin{document}${\hat z^{(1)}}$\end{document}(k+1)=9.580 75e0.269 33k-8.580 75, where k was the annual serial number and \begin{document}${\hat z^{(1)}}$\end{document}(k+1) was the disaster year serial number. The GM(1, 1) cataclysmic prediction model for the number of larvae of the first generation was:\begin{document}${\hat z^{(1)}}$\end{document}(k+1)=18.181 8e0.241 87k-17.181 8, and the second generation larval population was:\begin{document}${\hat z^{(1)}}$\end{document}(k+1)=20.123 7e0.197 58k-19.123 7. According to this model, fitted and observed values of known years were obtained. Results of a t test for t0.05 were not significant. The average annual accuracy of three disasters was 84.40%, 84.85%, and 84.08% with the total average accuracy of the first being 96.25%, of the second being 92.34%, and of the third being 94.09%. The predicted future times were as follows:for the wintering D. punctatus disaster of 2011, it would be another 10 years (2021) before the next overwintering. For the first generation D. punctatus larvae in the catastrophic year 2011, it would be another 11 years (2022), until the great occurrence of the first generation larvae. For the second generation D. punctatus larvae, the next disaster after 2011 would occur 9 years later (2020).  Conclusion  Thus, the catastrophe prediction method could be an ideal method for predicting the occurrence of larval cataclysm with D. punctatus.
Density index model of the Pinus massoniana plantation based on artifical neural network (ANN)
LIU Guangwu, CHEN Chen, WANG Keli
2020, 37(1): 100-104.   doi: 10.11833/j.issn.2095-0756.2020.01.013
[Abstract](32) [HTML](11) [PDF](0)
Abstract:
  Objective  To provide reference for wood production and quality improvement management measures, a study was conducted of the density index model of the Pinus massoniana plantation.  Method  Taking the P. massoniana plantation in the Boshan Forest Form in Henan Province as the research object with data collected of 147 standard plots, artifical neural network (ANN) model of the stand density index was established taking stand DBH as input vector and the plant number density as output vector and compared with Reineke's stand density index model.  Result  (1) The maximum density slope b of the P. massoniana plantation in the Boshan Forest Form was -1.516 3, the standardized mean DBH was 14 cm, the fitting accuracy of Reineke's stand density index model was 92.11%, and the effect of t test was significant. (2) The fitting accuracy of ANN model was 92.57% and the mean square error (MSE) was 0.001 469 7. (3)Either with Reineke density index or ANN technique employed, the young forest group demonstrate lower accuracy in fitting the variation trends of number density against that of stand DBH, which attributes to the smaller data of the young forest group.  Conclusion  The above established model was expected to provide reference for the operational decisions of the P. massoniana plantation in the Boshan Forest Form in Henan Province.
Site quality evaluation of Cunninghamia lanceolata plantations in Zhejiang Province based on maximum DBH growth rate
YANG Haibin, ZHANG Maozhen, DING Lixia, YU Xiaohui
2020, 37(1): 105-113.   doi: 10.11833/j.issn.2095-0756.2020.01.014
[Abstract](27) [HTML](15) [PDF](0)
Abstract:
  Objective  Forest site quality evaluation refers to the judgement and prediction of site suitability or potential productivity. The aim is to establish a site quality evaluation model of Cunninghamia lanceolata plantaion.  Method  A new site quality evaluation index, the maximum growth rate index of DBH, was proposed. Taken as the site evaluation index, and based on the National Forest Inventory(NFI) data of Zhejiang Province from 1994 to 2009, the maximum DBH growth rate for 529 permenant plots of C. lanceolata plantations was extracted from the NFI time series data as the site quality evaluation index of C. lanceolata plantations. Integrated with readily available site factors such as latitude, altitude, slope position, slope direction, slope, soil types, etc., and based on the quantitative theory Ⅰ method, a site quality evaluation model of C. lanceolata plantations was established.  Result  The statistical test value of the model is 14.723, and the complex correlation coefficient of the model is 0.606, which reaches a very significant level, and the effect of the model is satisfactory. The maximum DBH growth rate based on NFI is an appropriate index for site quality evaluation. The contribution of site factors such as slope direction, slope position, soil type, slope, latitude and altitude to the maximum growth rate of DBH decreases sequentially.  Conclusion  Based on NFI and quantitative theory Ⅰ, the overall index of site quality evaluation model of C. lanceolata plantations in Zhejiang Province is reasonable. It overcomes the dependence of traditional site quality evaluation on age, and can effectively use NFI historical data, which is suitable for forests of the same age and different age. The site quality evaluation model can effectively evaluate the site quality of the study area. It can not only evaluate the productivity of existing C. lanceolata plantations, but also predict the potential productivity of non-forest land.
Crown profile and volume compatibility model of Cunninghamia lanceolata in Fujian Province
WU Danzi, WANG Chengde, LI Liang, LIU Min
2020, 37(1): 114-121.   doi: 10.11833/j.issn.2095-0756.2020.01.015
[Abstract](33) [HTML](18) [PDF](0)
Abstract:
  Objective  Crown profile models can not only describe the radius at any position of the crown, but also predict the crown volume and the aboveground biomass. This paper developed a simultaneous equation system of crown profile model and crown volume prediction with the same set of model parameters using the data of 413 trees in 98 sample plots of Cunninghamia lanceolata plantation in Fujian Province.  Method  Four commonly used and integral crown profile models were selected, and the crown volume prediction models were derived by using integral method. The model equations were set up in pairs to establish the simultaneous equations of tree crown profile and volume compatibility, and the seemingly unrelated regression (SUR) process in SAS software module was used to estimate the parameters of the simultaneous equations model system. In order to eliminate the heteroscedasticity of the model, the weighted regression method was used to fit the model. The fitting accuracy and prediction accuracy of different model systems were compared and analyzed.  Result  The simultaneous equations based on model 4 had high fitting accuracy and good prediction performance. The fitting accuracy of the crown profile model and crown volume model reached 0.829 5 and 0.861 0 respectively, and the accuracy of prediction was 0.803 9 and 0.856 0 respectively. The collinearity problem of simultaneous equations was solved by the SUR method, and the heteroscedasticity in the model was eliminated to some extent by the weighted regression method.  Conclusion  The consistency model equation of crown profile-volume constructed in this paper can be used to derive the crown profile and volume model, which provides a theoretical basis for estimating the biomass of the aboveground part of trees.
Eucalyptus suitability in Guangxi based on machine learning algorithms
DU Yufei, WU Baoguo, CHEN Yuling
2020, 37(1): 122-128.   doi: 10.11833/j.issn.2095-0756.2020.01.016
[Abstract](38) [HTML](13) [PDF](1)
Abstract:
  Objective  The aim is to provide a new idea for tree species suitability evaluation, provide a support for scientific afforestation, and explore the relationship between site factors and tree suitability.  Method  Take a Eucalyptus plantation in Guangxi as the research object, 1 883 forest resource sub-compartment survey data of Guangxi state-owned Gaofeng Forest Farm were selected. Then, Naive Bayesian, Support Vector Machine, and Random Forest algorithm were used to evaluate the suitability of tree species and to construct a suitability classification model for Eucalyptus. Eleven site factors, namely, landform type, elevation, aspect, slope position, slope, litter thickness, humus layer thickness, soil layer thickness, gravel content, parent material, and soil type were input with the output being Eucalyptus suitability.  Result  The fitting accuracy of the three models was 63.18% for Naive Bayesian, 69.73% for Support Vector Machine, and 78.03% for Random Forest algorithm with a generalization accuracy of 64.33% for Naive Bayesian, 67.93% for Support Vector Machine, and 78.18% for Random Forest algorithm. The order of importance for site factors was elevation > soil layer thickness > aspect > slope > gravel content > litter thickness > slope position > humus layer thickness > soil type > landform type > parent material. Overall, Eucalyptus was more suitable for growth in areas of 200-350 m altitude and 80-100 cm soil layer thickness.  Conclusion  Thus, machine learning classification algorithms could be used to fit the non-linear relationship between tree species suitability and site factors.
GF-1 remote sensing data for Panax notoginseng planting information extraction in Wenshan, Yunnan Province
ZHU Zan, YUAN Xiping, GAN Shu, ZHANG Liangjie, ZHAO Qinghui
2020, 37(1): 129-135.   doi: 10.11833/j.issn.2095-0756.2020.01.017
[Abstract](31) [HTML](17) [PDF](0)
Abstract:
  Objective  Panax notoginseng, a kind of Chinese herbal medicine with high economic value and a close relationship to price fluctuation, could be very meaningful for a government's agricultural management departments to scientifically guide its planting scale and determine the price of macro controls. The aim is to obtain P. notoginseng planting information in real time and accurately.  Method  Four counties which mainly produce P. notoginseng in Wenshan Prefecture were taken as the research area. According to the characteristics of P. notoginseng growth, environment construction expert decision tree, the decision tree classification method to extract P. notoginseng shade patches and a method of refining processing on classification results through GIS spatial analysis, was used. Based on these, the area of P. notoginseng from the Gaofen-1 (GF-1) remote sensing images with 16 m resolution was extracted, and the extracted results were refined. Then, Google image was used, instead of field mapping, as a method to verify the area and classification accuracy of the image in order to obtain the accuracy and reliability of identification and evaluation of the Shade shed area for P. notoginseng.  Result  The accuracy of decision tree classification method is 87%, and that of visual interpretation method is 99%. The area accuracy of decision tree classification can reach 80%.  Conclusion  Compared with the traditional method of using high-resolution commercial images and artificial drawing spots, this method of extracting the P. notoginseng area could quickly determine P. notoginseng planting resources with higher accuracy, thereby providing basic data and effective technical methods for scientific supervision and value estimation of locally cultivated agricultural products.
Crops identification based on hyperspectral data and random forest method
WU Lizhou, WANG Xiaohui, WANG Zhihui, FANG Xin, ZHU Tingyu, DING Lixia
2020, 37(1): 136-142.   doi: 10.11833/j.issn.2095-0756.2020.01.018
[Abstract](43) [HTML](17) [PDF](2)
Abstract:
  Objective  The difference in hyperspectral reflectance of different crops is small, the subtle differences of the spectral feature enable identification of different crops. This aim is to find an effective way to select spectral feature bands from hundreds of bands and indentify different crops.  Method  The random forest method and the traditional methods were applied to analyze the reflective hyperspectra of 8 typical crops in Hangzhou, the spectral feature bands were extracted and the crops were distinguished. The traditional methods included first-order derivative, second-order derivative, logarithm of reciprocal, and the de-enveloping line method.  Result  The reflective hyperspectra of the different crops and the results processed by traditional methods were limited in crops identification, the spectral feature extracted by these traditional ways could not distinguish all of 8 crops. The random forest method was the most effective one for extraction of the spectral feature.  Conclusion  The extracted spectral feature bands were 550, 2 490, 370, 770, 560, 380, 540, 530, 570 and 350 nm, which not only were applied effectively to distinguish 8 crops, but also reflected the biochemical properties of the crops, which made sense to explain the classification with hyperspectral remote sensing.The random forest method fully demonstrated the advantages of hyperspectral remote sensing for crop identification and spectral feature extraction. The random forest classification can provide reference for large-scale crop fine classification with hyperspectral image.
Comprehensive evaluation of pumpkin cultivars based on a principal component analysis
TENG Zhiyan, CUI Yutong, YING Xuebing, ZHENG Weiwei, ZANG Yunxiang, ZHU Zhujun
2020, 37(1): 143-150.   doi: 10.11833/j.issn.2095-0756.2020.01.019
[Abstract](43) [HTML](14) [PDF](0)
Abstract:
  Objective   The aim is to quickly perform the difference among pumpkin cultivars, a suitable evaluation system was established for pumpkin.  Method   10 pumpkin cultivars were used to determine 30 indicators relevant to plant growth, fruit, texture, seed, as well as quality characteristics. Biological characteristics were obtained by ruler etc and analysis of nutritional quality were performed according to the methods from references. Each sample was analyzed five times and each experiment was conducted in five repetition (n=5). The results were expressed as means ±SE. Statistical comparisons were made by one-way analysis of variance (ANOVA) followed by Duncan's multiple range test (P=0.05). A principal component analysis was used for a comprehensive evaluation of the pumpkin cultivars and was constructed by taking the eigenvalues corresponding to the principal components and the ratio of a single principal component to the extracted principal components.  Result   There are strong differences among pumpkin cultivars. The first pistillate flower node of 'Doll' was earlier than that of others. Also, the branchiness of 'Red Chestnut' and 'NGMB' were strong. Although the chlorophyll content of 'Black Japan' was lowest, petiole diameter and leaf size of 'Black Japan' were higher than those of the other nine cultivars. Chlorophyll content of 'Rising Sun' and 'Jin Li' was highest. As for soluble sugar and starch content, 'Jin Li' was the best among all pumpkin cultivars. The highest chroma value and lowest chroma angle were found in 'Red Chestnut' which had the largest circumference and the most important single fruit. The flesh of the Cream series and 'Yellow Wolf' was relatively hard, and the toughness was very different for 'Cream NL1', 'Cream Y', and 'Yellow Wolf'. The seed number in 'Rising Sun' was highest, but in the cream pumpkin series the seed number was small. The seed weight of Red Chestnut was heaviest; whereas, the longitudinal diameter and thickness of the seeds were much larger than other cultivars. The principal component analysis extracted a total of five principal components with a cumulative contribution rate of 87.240%.  Conclusion   The best comprehensive score was found in 'Red Chestnut'; whereas, the worst was found in 'Cream NL1'. This study provided a theoretical reference for rapid screening of germplasm resources and pumpkin breeding.
Effects of maturity on seed quality of five conventional japonica rice cultivars
WANG Li, LI Xiaotian, ZHAO Guangwu
2020, 37(1): 151-157.   doi: 10.11833/j.issn.2095-0756.2020.01.020
[Abstract](44) [HTML](11) [PDF](0)
Abstract:
  Objective   The aim is to explore the effect of maturity on seed quality of conventional japonica rice.  Method  Five conventional japonica rice cultivars of 'Chunjiangnuo 6', 'Shaonuo 9714', 'Xiushui 121', 'Xiushui 14' and 'Zhejing 70' were used as materials, and the effects of maturity on moisture content of fresh rice seeds, 1 000-grain weight and germination rate were compared and analyzed.  Result   The moisture content of fresh seeds decreased with the increase of maturity. Compared with the seeds in the normal harvest period(68 DAF for 'Shaonuo 9714', 73 DAF for other four cultivars), the 1000-grain weight of dry seeds of the five rice cultivars reached the maximum value at 50-55 days after flowering, which increased by 0.9%-2.6%, especially for 'Chunjiangnuo 6' and 'Shaonuo 9714'. The germination rate of five rice cultivars increased first and then decreased with the extension of the harvest period, and reached the maximum at 50 days after flowering, increasing by 1.0%-7.1% compared with the seeds in the normal harvest period, especially for 'Xiushui 121'. The results of correlation analysis also showed that the moisture content of fresh seeds and 1000-grain weight had significant or extremely significant correlations with germination rate. The germination rate of seeds could be well predicted by establishing a quadratic equation model between moisture content of fresh seeds and germination rate of different rice cultivars, and the regression equation was:y=-0.099 6x2+5.739 5x+15.883 0.  Conclusion  The seed quality of the five rice cultivars was improving as the seed maturity increasing, and reached the maximum then did not improve. So harvesting on time is necessary.
Fiber morphology, microfibril angle and crystallinity of American red oak introduced
LI Congcong, PAN Biao, WANG Hui, HUANG Libin
2020, 37(1): 158-164.   doi: 10.11833/j.issn.2095-0756.2020.01.021
[Abstract](31) [HTML](17) [PDF](1)
Abstract:
  Objective   Measuring and analyzingthe fiber morphology, microfibril angle and crystallinity can provide a theoretical basis for its quality prediction and utilization.  Method   Taking 14-year-old Quercus nuttallii, Q. nigra and Q. shumardii as the research object, with the maceration method and X-ray diffractometer (XRD) employed, a study is conducted of their fiber morphology, microfibril angle and crystallinity with a regression and variance analysis made of the data.  Result   (1) The fiber lengths of the three species of oak are 1 172.14, 1 178.68 and 1 162.45 μm, the fiber widths of the three species of oak are 15.86, 16.56 and 16.91 μm with no significant differences among species (P>0.05). The double-wall thickness of three species of oak are 10.23, 11.19 and 10.96 μm, and the wall thickness-lumen diameter ratios of the three species of oak are 1.85, 2.10 and 1.91 with significant differences among species (P < 0.05). The microfibril angles of three species of oak are 33.79°, 30.48° and 34.10° and the crystallinities of the three oak species are 51.35%, 53.30% and 52.97% with extremely significant differences among species (P < 0.01). (2) The fiber length, the fiber width, the double-wall thickness, the wall thickness-lumen diameter ratio and the crystallinity of three species of oak displayed an ascending trend from pith to bark. The microfibril angle displayed a descending trend from pith to bark with some fluctuations between the rings.  Conclusion   The radial change of the fiber morphology, the microfibril angle and the crystallinity of 14-years-old Q. nuttallii, Q. nigra and Q. shumardii was not stable but stayed in the juvenile stage. Also, the fiber length, fiber width, double wall thickness and microfibril angle demonstrate favorable fitting with growth rings.
Effects of CuAz preservative on the antiseptic performance and physical and mechanical properties of poplar scrimber
BAO Minzhen, YU Wenji, CHEN Yuhe, YU Yanglun, WU Zaixing, HE Sheng, LI Neng
2020, 37(1): 165-170.   doi: 10.11833/j.issn.2095-0756.2020.01.022
[Abstract](39) [HTML](15) [PDF](0)
Abstract:
  Objective   The research aim is to improve the outdoor durability of scrimber.  Method   Water-soluble CuAz preservative was used to impregnate poplar fibrous veneer by means of atmospheric pressure and vacuum-pressure, respectively. The effects of CuAz preservative on chemical composition, antiseptic performance and physical and mechanical properties of scrimber were investigated.  Result   CuAz preservative could enter the cell lumen and cell wall of vessel, wood ray and fiber, and complexed with hemicellulose and lignin of cell wall. After 12 weeks of decay test by Coriolus versicolor and Gloeophyllum trabeum, the mass loss rate of the antiseptic scrimber was less than 10%, reaching the grade of strong decay resistance. The water absorption rate, thickness swelling rate and width swelling rate of antiseptic scrimber were lower than those of untreated scrimber. The modulus of elasticity and horizontal shear strength of anticorrosive scrimber were higher than those of untreated scrimber, while the static bending strength of antiseptic scrimber was lower than that of control scrimber.  Conclusion   Water-soluble CuAz preservative can improve the scrimber's antiseptic performance and physical and mechanical properties.
Review
Research advances in the influence of vegetation on urban heat island effect
CUI Fengjiao, SHAO Feng, QI Feng, WANG Yujie, ZHANG Tailong, YU Haiying
2020, 37(1): 171-181.   doi: 10.11833/j.issn.2095-0756.2020.01.023
[Abstract](46) [HTML](16) [PDF](1)
Abstract:
Heat island effect leads to the deterioration of urban residential thermal environment and the consumption of large amount of energy. How to effectively alleviate the heat island effect has become an urgent problem. Vegetation can reduce air temperature and increase humidity through long-wave and short-wave radiation and transpiration. Therefore, urban greening has become an important technical means to alleviate the heat island effect. In order to continuously promote the research on the impact of vegetation on urban heat island effect, this paper reviews and summarizes the relevant studies at home and abroad from the aspects of research status, research content and research methods, existing problems and prospects. Firstly, the research progress of urban heat island effect at home and abroad is reviewed from the perspectives of research origin and observation methods. On this basis, the regulation mechanism of vegetation on urban air temperature is further analyzed, and the mechanism of vegetation cooling effect is further summarized from the perspectives of vegetation vertical structure, horizontal structure, canopy structure and vegetation remote sensing index. Among them, vegetation canopy structure contains parameters such as leaf area index, canopy width, canopy density and three-dimensional green biomass, while remote sensing index contains parameters such as normalized vegetation index, vegetation coverage and greenness vegetation index. This paper not only summarizes the research status at home and abroad, but also concludes the main problems in the current study of the cooling effect of green spaces, and puts forward suggestions for future research directions, which aims to provide references for follow-up research.
Scientific notes
Pollen viability and stigma receptivity of Heimia myrtifolia
LUO Qingqing, ZHENG Gang, GU Cuihua, GU Fan, CHEN Kai, ZHENG Shaoyu
2020, 37(1): 182-187.   doi: 10.11833/j.issn.2095-0756.2020.01.024
[Abstract](36) [HTML](18) [PDF](0)
Abstract:
  Objective   To determine the effects of different temperatures, sucrose concentrations, and boric acid concentrations on pollen germination and pollen tube growth of Heimia myrtifolia, and study the effects of different concentrations of naphthylacetic acid(NAA), gibberellin (GA3), and 6-benzyladenine (6-BA) on stigma receptivity of H. myrtifolia.  Method   In vitro pollen germination, the agar medium germination and benzidine-hydrogen peroxide methods were used. The stigma and pollen were observed under a scanning electron microscope.  Result   The effects of different temperatures, sucrose concentrations, and boric acid concentrations on pollen germination and on pollen tube growth were significantly different (P < 0.05). Suitable concentrations of boric acid and sucrose on pollen germination ranged from 0.05% to 0.10% and on pollen tube growth ranged from 5% to 15%. The suitable storage temperature was 35℃. The stigma of H. myrtifolia had different receptivity during the blooming period with the highest receptivity 6-8 hours after blooming. The effects of the hormone with different concentrations of NAA, GA3, and 6-BA on pollen viability and growth of H. myrtifolia were significantly different (P < 0.05) with the optimum concentrations being 10.0 mg·L-1 NAA, 200.0-400.0 mg·L-1 GA3, and 20.0 mg·L-1 6-BA. Stigma diameter of H. myrtifolia ranged from 425.78 μm to 546.93 μm. Scanning electron microscopy of the H. myrtifolia pollen showed that the polar axis length ranged from 23.15 μm to 26.74 μm, and the equatorial axis length ranged from 18.02 μm to 20.03 μm qualifying it as a small-sized pollen.  Conclusion   The optimum time for artificial pollination of H. myrtifolia was 6-8 hours after anthesis, and hormone stimulation of a specific concentration could effectively improve the seed setting rate.
A micro-cutting system for breeding of Phoebe bournei
XIAO Yeling, TONG Zaikang, WU Jianhui
2020, 37(1): 188-194.   doi: 10.11833/j.issn.2095-0756.2020.01.025
[Abstract](58) [HTML](21) [PDF](1)
Abstract:
  Objective   The mature embryos of Phoebo bournei were used as explants, and a variety of methods were used to establish the micro-cutting and breeding system of P. bournei.  Method   To explore the effects of different cotyledon excision intensities on embryo browning, the type and concentration of anti-browning agent, the effect of indolebutyric acid (IBA) on the germination of near mature embryos, and the rooting of sterile seedlings, nearly-mature cotyledon embryos of P. bournei were used as explants.  Result   The main browning part of P. bournei nearly-mature cotyledon embryos was the cotyledon. The embryo could germinate but it grew weak after the cotyledon was cut off. The addition of anti-browning agents inhibited the browning. The optimal culture medium for germination of the nearly-mature cotyledon embryo was 1/2 Murashige and Skoog (MS) + 0.2 mg·L-1 IBA + 2 g·L-1 polyvinylpyrrolidone (PVP) with a germination rate of 89.7%. The optimal culture medium for rooting of an aseptic seedling was 1/2 MS + 1.5 mg·L-1 IBA + 2 g·L-1 PVP, and the rooting rate of the apical bud was 100%. The average number of roots was 3.86, and the average root length was 1.56 cm; whereas, the rooting rate of the lateral bud was 60.3%. The average number of roots was 1.55, and the average root length was 0.85 cm. Also, the three selected strains had a reproductive coefficient of 24.40.  Conclusion   The results could lay a foundation for the breeding of further varieties.

Bimonthly, Start in 1984

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