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    10 January 2019, Volume 38 Issue 1
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    Effects of thinning on structure and spatial pattern of dominant populations in Pinus tabulifomisplantations.
    DUAN Meng-cheng, WANG Guo-liang, SHI Jun-yi, ZHOU Hao-xiang
    2019, 38(1):  1-10. 
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    We assessed the effects of moderate and heavy thinning intensities (30% and 45%) after 12 years on the structure, spatial distribution, and seedling regeneration of dominant canopy species, Pinus tabuliformisand Quercus liaotungensis, inP. tabulifomis plantations in the Huanglong Mountain, Shaanxi Province, northwest China. The thinning promoted a shift in curve ofdiameter class from positive distribution to negative one. The proportion of trees with large diameter (DBH≥20 cm) under moderate and heavy thinning intensities was higher than that under the control (nonthinning plots). Moderate and heavy thinning intensities significantly increased understory structure diversity. The diversity indices in the moderate and heavy thinning plots were 1.34 and 1.52 times as higher as those in the control, respectively. The populations of P. tabuliformiswere evenly distributed at the small scale (0-4.5, 0.5-4 m) under moderate and heavy thinning, but were aggregated at 2-4 m under the control, and were randomly distributed for all treatments at large scale. At 0-10 m scale, there was no difference in cumulative biomass between thinning treatment and control. Moderate thinning significantly increased the cumulative biomass at the scale of 15-25 m, with an increase of 29.55% at 25 m scale compared with the control. Heavy thinning increased the cumulative biomass at 25 m scale by 8.35%. There was no correlation between mature trees of P. tabuliformis and Q. liaotungensis at the entire spatial scale under heavy thinning. The age class of seedlings and saplings ofQ. liaotungensshowed an inverted “J” growth type under heavy thinning, suggesting that such an intensity would accelerate the transition from coniferous plantation to coniferous-broadleaved forest. In conclusion, thinning can optimize the structure of plantations, change the distribution pattern of biomass, and affect the succession of the community, which provides methodological and theoretical support for the directional cultivation of ecological plantations.
    Species composition and community structure of natural mixed needle and broad-leaved forest in Shennongjia.
    ZHOU Qiu-jing, HAN Wen-bin, ZHAO Chang-ming, WANG Yang, CHEN Fang-qing, XIE Zong-qiang
    2019, 38(1):  11-18. 
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    The natural needle and broad-leaved mixed forest is a vertical zonal vegetation in the Shennongjia Mountains, with important ecological and economic values. To gain insights into the structure, dynamics, and the maintenance of species diversity of the natural mixed needle and broad-leaf forest community, a 1hm2 forest plot was established in Shennongjia National Nature Reserve, Hubei Province. The species composition, sizeclass structure of diameter at breast height (DBH), and spatial distribution of dominant species were analyzed. A total of 5321 living individuals were recorded in the plot, belonging to 44 species, 26 genera, and 14 families. There were very few conifer species, with only Abies fargesii and Pinus armandii present in the plot. The total importance values of Abies fargesii, Crataegus wilsonii and Populus davidiana was 50.28%, and that of other broad-leaved species was 46.06%. The DBH class structure showed a reversed “J” shape with abundant saplings in the understory. Among the top three dominant species with respect to importance value, both Abies fargesii and Crataegus wilsonii had a DBH class structure of reversed “J” shape, indicating their regeneration status were good. On the contrary, the sizeclass structure of DBH of Populus davidiana was close to the normal distribution, the saplings were scarce, and the population had a tendency to decline.Abies fargesii,Crataegus wilsonii and Populus davidiana showed obvious habitat preference. With the increases of sampling scale size,Crataegus wilsonii and Populus davidiana did not change their aggregated distribution, while the spatial distribution of Abies fargesii changed from a clustered, via a random, to a uniform distribution. The species richness of broadleaved trees was higher than that of coniferous trees in the mixed needle and broad-leaved forest in Shennongjia. However, if only the top three dominant species on the importance value sorting list were considered, the importance values of needle and broad-leaved species were similar and the community structure was stable.
    Spatial distribution patterns of Ammopiptanthus mongolicus degraded populations in relation to developmental stages in western Erdos of Inner Mongolia.
    SHEN Jing-xin, YUAN Wei-jie, YU Yi, GAO Yong, WANG Ji, SONG Xiao-min
    2019, 38(1):  19-26. 
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    We examined the spatial distribution and associations of Ammopiptanthus mongolicus with different recession degrees and at different developmental stages in West Ordos National Nature Reserve in Inner Mongolia, China, with O-ring statistical analysis method. Spatial distribution patterns of A. mongolicus populations varied with different recession degrees, depending on the scale level. Populations with severe and moderate recession degrees performed random distribution at 0-50 m scale, while those with mild recession displayed clumped distribution, and shifted to random distribution with increasing scales. Healthy population showed clumped distribution at the small scale, uniform distribution at the middle scale, and random distribution at the large scale. Spatial distribution patterns of A. mongolicus varied with developmental stages. The population with young and old age classes displayed random distribution at the scale level of 0-50 m, whereas population with young-middle age class showed clumped distribution at the middle scale and random distribution at other scales. The populations with middle age class and middle-old age class all showed clumped distribution at the small scale, but showed uniform distribution with increasing scale and random distribution at the large scale. Moreover, the spatial association of A. mongolicus varied with developmental stages. There was no correlation between the population at the young class and those at different developmental stages at 0-50 m scale. Beginning with the populations at the middle-young class, the associations started to appear with the increase of age class. There was a positive correlation between these high age classes at most scales, whereas there was a negative correlation between the populations of middle class and middle-old class at the 5 m scale.
    Microclimate regulating effects of plant communities with different structures in summer and winter in Nanjing City.
    ZHANG Ming-juan, WEI Xiao, SU Xiao-lei, LI Chen, LIU Pei-fan
    2019, 38(1):  27-34. 
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    The microclimate regulation ability of plants is of great significance for improving the comfort of living environment in urban public spaces. Taking the parks and plazas in Nanjing City as the research objects, we analyzed the differences of temperature, humidity and thermal comfort (measured by temperature-humidity index) regulating ability of five structural types of communities (including single-layer grassland, evergreen single-layer woodland, evergreen tree-grass composite woodland, deciduous singlelayer woodland, and deciduous tree-grass composite woodland) in winter and summer by field measurement. The results showed that in summer, all communities had significant or extremely significant cooling and humidification effects (P<0.05 orP<0.01), but there was no significant difference among the four woodland types in their cooling and thermal comfort regulating ability. The effects of regulating temperature, humidity and thermal comfort of four woodland types were significantly or extremely significantly higher than those of the grassland (P<0.05 or P<0.01). In winter, the evergreen single-layer tree woodland or evergreen tree-grass composite woodland worsened the thermal comfort with significant cooling effect (P<0.05 or P<0.01), while the grassland and deciduous woodlands had no significant effect on microclimate. Except for the significant interaction between the deciduous tree and the understory in cooling effect in summer (P<0.05), the understory and the tree layer had no significant interaction in terms of other microclimate regulation effects. Our results suggested that the proportion of deciduous woodland could be increased to improve thermal comfort in cold winter and hot summer regions.
    Phenotypic diversity of leaf morphologic traits of Davidia involucrata natural populations in Sichuan Province.
    ZHANG Teng-ju, CHEN Xiao-hong, KANG Xi-kun, LIU Jing
    2019, 38(1):  35-43. 
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    Dove tree (Davidia involucrata) is one of the national first-class protective plants in China. In order to understand its variation and adaptation mechanism of leaf phenotypic traits, 11 leaf phenotypic traits of 15 populations were investigated in Sichuan Province. The variation degrees of 11 leaf phenotypic traits were tested by nested analysis of variance, correlation analysis, and cluster analysis. Significant and abundant variations of 11 phenotypic traits were observed at inter and intra population levels. The mean phenotypic differentiation coefficient among populations was 37%, which was less than that within populations (63%), indicating that the variation within populations was the main source of the phenotypic variation of dove tree. The mean coefficient of variation (CV) of 11 phenotypic indices was 16.22%, ranging from 4.32% to 29.10%. The mean dispersion coefficient of populations was 53.21%, ranging from 39.38% to 87.14%. The results of correlation analysis showed that there were significant correlations among leaf length, leaf width, left leaf width, and petiole length, implying that some leaf phenotypic traits of dove tree coordinate each other in the 15 dove tree populations. Leaf size, leaf thickness and petiole size were negatively correlated with latitude and altitude, with the leaves being gradually smaller and thinner with elevated latitude and altitude. The mean values of Shannon index for leaf phenotypic traits and for dove tree populations were 2.360 and 2.331 respectively, and were well-distributed as well. Results from the clustering analysis showed that the 15 dove tree populations in Sichuan Province could be classified into three groups, with a lack of continuous geographical variations. In conclusion, the dove tree populations in Sichuan Province had higher phenotypic variations, which were related with the heredity and habitats. Our results provided scientific basis for conservation and utilization of dove tree resources.
    Effects of simulated nitrogen deposition and earthworm addition on ecosystem respiration of Pinus tabuliformis and Quercus liaotungensisseedlings.
    YANG Lu, ZHAO Bo, CHEN Ping, ZHAO Xiu-hai
    2019, 38(1):  44-50. 
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    To explore the effects of nitrogen (N) deposition and earthworm addition on seedling’s ecosystem respiratory rates, we used LI-8100 soil carbon flux measurement system to measure the ecosystem respiratory rates of Pinus tabuliformis andQuercus liaotungensis seedlings under simulated N deposition (0, 50, 100 kg N·hm-2·a-1, designated as CK, LN, HN respectively) and earthworm addition (no earthworm addition, A; earthworm addition, B) in the nursery located near Lingkong Mountain Nature Reserve, Shanxi Province from June to September in 2017. The results showed that the responses of ecosystem respiration rate of seedlings to N deposition differed between the two species. N deposition had no significant effects on the ecosystem respiration rate ofP. tabuliformis seedlings (P>0.05), but significantly affected that of Q. liaotungensis seedlings (P<0.01). In low LN and HN treatments, the ecosystem respiration rate of Q. liaotungensis seedlings increased by 0.61% and 3.65% respectively under no earthworm addition, and increased by 6.67% and 31.82% respectively under earthworm addition. Earthworm addition promoted the ecosystem respiration rate of P. tabuliformis(P<0.01)and Q. liaotungensis (P<0.05) seedlings, with increases of 16.04%, 40.86%, and 1.15% for P. tabuliformis and 0.31%, 6.34%, and 27.57% for Q. liaotungensis at CK, LN, and HN, respectively. N deposition interacted with earthworm addition to promote the ecosystem respiration rate of both species (P<0.05). arthworm addition increased the temperature coefficients of respiration (Q10 values) of P. tabuliformis in various N addition treatments, while decreased that of Q. liaotungensis. The Q10 values of P. tabuliformis were decreased and then increased with the increasing N level, while the Q10 values of Q. liaotungensis were increased and then decreased with the increasing N level.
    Effects of water stress on phenotypic plasticity of Quercus mongolicaseedlings grown in two soil substrates.
    WANG Jun, JI Li, ZHANG Zhong-hui, WANG Fang, LI Yan-long, LU Zhi-min, YANG Yu-chun
    2019, 38(1):  51-59. 
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    Soil moisture is one of the most important factors affecting plant growth. Investigating the responses of seedling growth and biomass allocation to drought stress on different soil substrates could provide theoretical support for the cultivation of high-quality afforestation seedlings. Here, 2-year-old Quercus mongolica seedlings were chosen as research object and an experiment was conducted under completely random design and with two factors (water levels and substrates). There were four water levels \[normal water supply (CK), mild water stress (T1), moderate water stress (T2), and severe water stress (T3), corresponding to 80%, 60%, 40%, and 20% of field water capacity respectively) in humus and clay. The height, ground diameter, crown area, leaf area, specific leaf area (SLA) and organ biomass of seedlings were measured in 20, 40, and 60 days. The results showed that the height and ground diameter of seedlings were decreased with increasing water stress intensity, and they had a significant difference betweenhumus and clay. The SLA of seedlings significantly differed among water stresses. The leaf areaindex and leaf biomass were higher in humus than in clay. After 60 days of water stress, with increased stress intensity, the total biomass and organ biomass  showed a descend trend in humus. The total, root and leaf biomass were 39.98, 22.32, 6.16 g per seedling and were the highest in T1 in clay. The results of redundancy analysis showed that soil total N, total P, available P, evaporation rate, permeation rate and aeration porosity had a significantly positive relation with seedling morphology, whereas soil bulk density, total porosity and water absorption capacity exhibited a negative relation with seedling morphology. The plasticity index of organs’ dry weight was higher than organs’ mass ratio on the whole. The soil substrates with an abundant nutrients and favorable soil structure could alleviate the negative effects of water deficiency on the growth of Q. mongolica seedlings. It’s necessary to rationally dispose soil and manage water for seedlings and thus improve the tolerance of seedlings to environment and their performance in afforestation.
    Reproductive allocation and floral characteristic of Saussurea katochaete in relation to elevation.
    MAO Wan-yi, WANG Yi-feng, YANG Li-long, SONG Wei-dong, MA Wen-mei
    2019, 38(1):  60-66. 
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    To understand reproductive allocation and floral traits of alpine plants in response to elevation and to clarify reproductive strategies of Sausserua plants at high elevation, we investigated the reproductive allocation and floral characteristic of Saussurea katochaete Maxim at different elevations along Tibetan Plateau. The results showed that there was a significantly negative correlation between the individual size, vegetative organ biomass, the number of tubular flowers, capitulum biomass and elevation (P<0.01). The length of filaments and the number of pollen were negatively correlated with elevation (P<0.01), while the anther length, style length, and style branch length were significantly and positively correlated with elevation (P<0.01). Reproductive organ biomass and reproductive allocation depended on individual size, with the former showing a positive correlation with individual size (P=0.024) but the latter showing a negative correlation with individual size (P<0.01). There was significantly negative correlations between the number of tubular florets and the weight of capitulum (P<0.01), between the number of tubular florets and single tubular floret weight (P<0.01), and between the pistil weight and stamen weight(P=0.024). Our results indicated that elevation had a great impact on the biomass of S. katochaete. The individual size was closely related to plant reproductive allocation strategy. As the elevation increased, S. katochaete adapted to the environment and improved its own fitness through the trade-offs of the flower number versus weight and pistil weight versus stamen weight.
    The effects of shading on photosynthetic characteristics and growth of Dendrocalamopsis oldhami seedlings in container.
    DU Lan, XIE Jin-zhong, LAI Qiu-xiang, CHEN Liang, ZHANG Wei, CHEN Sheng, XIA Jie, WU Wei
    2019, 38(1):  67-73. 
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    Dendrocalamopsis oldhami is an important bamboo species for afforestation in south subtropical China, with a broad application prospect in culm and shoot production. In this study, photosynthetic capacity, chlorophyll fluorescence parameters, and growth characteristics of D. oldhamiwere investigated under three shading treatments: no shading as control (full illumination, L0), singlelayer shading (70% of full illumination, L1), and two-layer shading (30% of full illumination, L2). We found that treatment L1 increased the apparent quantum efficiency and net photosynthetic rate of D. oldhami leaves, while treatment L2 had the lower values, with significant difference among the three treatments (P<0.05). The dark respiration rate (Rd), light compensation point (LCP), and light saturation point (LSP) declined with decreasing light levels. For the chlorophyll fluorescence parameters, shading significantly increased PSⅡ primary energy conversion efficiency (Fv/Fm), PSⅡ potential activity (Fv/Fo) and electron transport rate (ETR), and decreased photochemical efficiency of PSⅡ (Fv′/Fm′), photochemical quenching (qP) and nonphotochemical quenching (NPQ). Moreover, shading significantly increasedleaf chlorophyll content (Chla+Chlb) and Chla/Chlb ratio, with a significant difference between treatments L0 and L2 (P<0.05). Shading enhanced the growth performance of D. oldhami, with greatest basal diameter in treatment L1. Leaf area increased with the increases of shading levels. There was no effect of shading on plant height (P>0.05). Thus, D. oldhami has a strong adaptability to weak shading environment and an adjustable inherent mechanism to utilize low intensity light. However, low light intensity would restrict the growth ofD. oldhami container seedlings.
    Species composition and community structure of Pinus tabuliformis forest in the South Lake Park in Changchun.
    LI Ming-rui, CUI Shuang, ZHENG Hai-feng, HE Xing-yuan, TANG Ze, ZHANG Si-yu, SHEN Guo-qiang
    2019, 38(1):  74-82. 
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    We analyzed the community structure and floristic characteristics of Pinus tabuliformis forest in the South Lake Park in Changchun. Based on the first-order pattern test discriminant theory, the species composition and structure of P. tabuliformisforest were studied using diameter class as an age-level proxy indicator. The results showed that the trees belong to seven families, nine genera and 10 species. That means the tree composition was monotonous and unreasonable at species, genus, and family levels. The floristic element at the family level was mainly dominated by pan-tropical with certain proportions of cosmopolitan and north temperate elements. The north temperate was the dominant of genus. The abundance and importance value of P. tabuliformis in the communities were predominant, but its dominance in DBH and height was not obvious. There was a normal distribution in diameter class forP. tabuliformis. The communities were dominated by middle-aged trees, followed by near-mature and mature trees, with few seedlings and saplings. These communities were stable but with poor regeneration ability. The P. tabuliformis population in all the communities showed aggregated distribution, while a uniform distribution occurred on each single plant community. The types of population aggregation changed with different ages in spatial pattern discrimination. With the shrinking of the spatial scale, the distribution pattern of P. tabuliformis population changed from aggregated type to uniform type.
    Effects of altitude on the variation of appearance, nutrition, and taste for bamboo shoots of Pleioblastus amarusin Shaxian, Fujian Province.
    GUO Zi-wu, YANG Li-ting, LIN Hua, CHEN Shuang-lin, YANG Qing-ping
    2019, 38(1):  83-88. 
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    To clarify the difference of shoot quality from different altitudes and provide theoretical guidance to the management of Pleioblastus amarusforest for producing highquality shoots, we analyzed the appearance, nutrition, and taste of bamboo shoots from three altitudes (190±20 m, 380±20 m, 600±20 m). The results showed that with increasing altitude, individual weight, diameter, length, and edible rate of shoots generally decreased. Those parameters of bamboo shoots from low and middle altitudes were better than that from high altitude. In addition, the contents of protein, cellulose, and lignin in bamboo shoots first decreased and then increased, while fat and starch contents changed in an opposite trend. Protein content in shoots from low altitude was obviously higher than that from middle and high altitudes. The cellulose and lignin content in shoots from low and middle altitudes was lower than that from high altitude, while starch content changed in an opposite trend. The fat content significantly differed among the three altitudes. Moreover, with increasing altitude, soluble sugar content and sugar to acid ratio increased at first and then decreased, while the contents of tannin, oxalic acid, total acids decreased at first and then increased. Soluble sugar content and sugar to acid ratio of shoots from low and middle altitudes were significantly higher than that from high altitude, while oxalic acid and total acid contents of the two formers was obviously lower than that of the latter. There was no significant difference in tannin content among the three altitudes. Moreover, the contents of total amino acids and components and their proportions fell at first and then rose. The contents of total amino acids and components of shoots from middle altitude were lower than those from low and high altitudes, while the proportion of aromatic amino acid was higher. Our results indicate that altitude greatly influences shoot appearance, nutrition and taste, and that the shoots from low and middle altitudes have more favorable quality.
    Water use characteristics of main species in different shrub encroachment stages on Ordos Plateau.
    LI Qiao-yan, LAI Li-ming, ZHOU Ji-hua, JIANG Lian-he, YANG Liu, YI San-gui, SUN Qing-lin, ZHENG Yuan-run
    2019, 38(1):  89-96. 
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    Shrub encroachment occurs in degraded grasslands worldwide. Most hypotheses about shrub encroachment suggest that the differences of water use strategies between shrubs and herbaceous species are important, but with limited empirical evidence. Based on filed survey of four different succession stages (Agriophyllum squarrosum community in shifting sandy land, Artemisia ordosica community in semi-fixed sandy land, A. ordosica community in fixed sandy land, and Stipa bungeana community in fixed sandy land) on the Ordos Plateau, we examined the changes of water use characters of dominant species in different succession stages by determining water source through δ18O analysis. In different succession stages, herbaceous plants mainly used water from shallow soil layer (0-20 cm), whereas shrubs predominantly used water from middle or deep soil layers (50-200 cm). The plasticity of water use by shrubs was stronger than that of herbaceous plants. When suffering water stress, shrubs can change their water use sources to different soil layers according to water availability. These findings improve our understanding of water use strategy of the main species at different successional stages on the Ordos Plateau. The results suggest that it is crucial to reduce human disturbances such as overgrazing, to improve soil structure and increase soil moisture in shallow soil, and consequently to restore zonal S. bungeana steppe from A. ordosica encroached grassland on the Ordos Plateau.
    The application of high-sensitivity thermocouple in monitoring the sap flow and transpirational cooling in Ferula krylovii leaves.
    ZHANG Ping, HAO Xiu-ying, YU Rui-feng, ZHOU Hong-mei, ZHU Jian-jun
    2019, 38(1):  97-103. 
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    We used high-sensitivity thermocouple was to monitor sap flow, especially for the sap flow and transpirational cooling in the leaves of Ferula krylovii, the measurement of which was difficult with the conventional sap flow meter. The thermal signals from sap flow, leaf temperature, and air temperature were recorded with highsensitivity thermocouples. The results showed that the thermal signal of sap flow could be expressed either with the value of the thermal peak or with the areas below the thermal peak which showed a higher sensitivity. The transpiration rate in the leaves of F. kryloviiincreased quickly and steadily with the increases of light intensity and air temperature, and decreased only when light intensity and air temperature began to decrease. The fact that no sign of transpiration regulation was seen indicates that the F. krylovii was a highly water consuming plant. The plant could maintain a temperature constantly below or equal to the air temperature through transpirational cooling, with a maximum decline of 6 ℃ in the leavesbelow the air temperature, thus effectively prevented the possible high temperature injury due to the absorption of high solar radiation at a price of large amount of water consumption. Our results indicated that the high-sensitivity thermocouples could be used not only in detecting sap flow, but also in cases that were difficult for the normal sap flow meters, with low cost.
    Effects of nitrogen addition on ecosystem carbon exchange in a sandy grassland.
    SUN Xue-kai, LIN Li-tao, YU Zhan-yuan, HUANG Yue, ZENG De-hui
    2019, 38(1):  104-112. 
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    Ecosystem carbon exchange is a key component of terrestrial ecosystem carbon cycle. Nitrogen (N) deposition is one of the most common disturbances in grassland ecosystems. In this study, we assessed the effects of N addition on ecosystem carbon exchange and its responses to the variations of temperature and moisture. Results showed that the daily variations of NEE, ER and GEP under N addition showed the same trend, but different magnitudes of variation during different growing periods with a significant level at vegetation vigorous period (P<0.05). NEE had no significant correlation with sunshine duration and temperature (P>0.05), but was positively correlated with biomass and soil moisture (P<0.05). N addition enhanced the sensitivity of NEE to soil moisture, from 0.18 to 0.37. Both ER and GEP showed a significant exponential relationship with sunshine duration and temperature (P<0.01). N addition increased the sensitivity of ER and GEP to sunshine duration and temperature. Aboveground biomass had a good correlation with ER and GEP at the beginning of the growing season. Changes of biomass following Naddition may play an important role in mediating the effects of N addition on grassland ecosystem carbon exchange.
    Diversity of soil ammonia-oxidizing bacteria under Caragana microphyllacommunity in Horqin Sandy Land.
    GAO Ting-ting, ZHANG Ying, YANG Sheng, CUI Zhen-bo, CAO Cheng-you
    2019, 38(1):  113-120. 
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    Soil nitrogen transformation is primarily driven by related functional soil microbes. Ammonia oxidation by ammonia-oxidizing bacteria (AOB) is the rate-limiting step of nitrification. During the processes of desertification and restoration, soil microbial communities are significantly affected by the changes of vegetation and soil. In this study, we investigated the diversity and community structure of soil AOB marked by amoA gene with clone library and quantitative PCR techniques under 30-year-old Caragana microphyllasandfixation plantation and moving sandy dune in Horqin Sandy Land. We found that the diversity of AOB in the C. microphyllasoil was very low, with only some Nitrosospira species being observed. During the positive and negative processes of desertification, the structure of soil AOB communities mainly varied in quantity, while the composition of soil AOB communities remained unchanged. These results indicate that soil AOB community structure in moving sandy dune can be restored to its original condition by planting C. microphylla. Soil total N and P concentrations are major environmental factors affecting AOB community structure.
    Effects of different years of recovery on vegetation and soil characteristics of open-pit coal mine dumps in alpine region.
    JIN Li-qun, LI Xi-lai, SUN Hua-fang, YANG Xin-guang, ZHANG-jing
    2019, 38(1):  121-128. 
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    To understand vegetation restoration in alpine coal mining area, we investigated the vegetation and soil characteristics of sites with soil inoculation under different restoration durations (1, 3, and 5 years) in Jiangcang mining area of Muli Coal Field. The results showed that, compared with one-year duration of restoration, the aboveground biomass of vegetation was significantly increased three years after restoration(P<0.05). The vegetation height, coverage, aboveground biomass, seed number, and seeding height and coverage were significantly higher after five years restoration(P<0.05). Except soil total K, soil physicochemical propertiesimproved over time (P<0.05). The abundance of soil bacteria decreased by 19% (P<0.05), while that of soil fungi and actinomycetes significantly increased(P<0.05). Correlation analysis showed that soil physicochemical properties (except soil pH) were significantly correlated with vegetation characteristics. The abundance of soil fungi and actinomycetes was significantly correlated with soil nitrogen, organic matter and water content(P<0.05). Our results indicated that the recovery of soil physical properties lagged behind chemical properties during vegetation restoration in alpine coal mining region. In the early stage of restoration, application of enough organic fertilizer combined timely addition of chemical fertilizer would accelerate the restoration of vegetation in alpine coal mining area.
    Effects of combined application of Chinese milk vetch (Astragalus sinicus L.) and nitrogen fertilizer on paddy soil carbon pool.
    MA Yan-qin, HUANG Guo-qin
    2019, 38(1):  129-135. 
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    Chinese milk vetch (Astragalus sinicus L.) is an important green manure crop of paddy fields in southern China. Understanding the effects of planting Chinese milk vetch in combination with nitrogen fertilizer application on soil organic carbon is crucial for the optimization of fertilizer application and soil fertility management, which could provide a theoretical basis for the sustainable development of agriculture in paddy fields. There were five treatments, including no Chinese milk vetch planting in winter + no nitrogen application (CK), planting Chinese milk vetch without nitrogen application, planting Chinese milk vetch with nitrogen-reducing application, planting Chinese milk vetch with conventional-level nitrogen application, and planting Chinese milk vetch with high-level nitrogen application. The results showed that, compared with CK, soil total organic carbon and active organic carbon under the treatment of planting Chinese milk vetch alone increased by 14% and 22% respectively. For the four treatments of planting Chinese milk vetch, soil microbial biomass carbon, soil microbial entropy and carbon pool management index increased by 70%, 58%, and 8%, respectively. For the three treatments of planting Chinese milk vetch with varied nitrogen application levels, total organic carbon, active organic carbon, and soil microbial entropy increased by 8%, 15%, and 72%, respectively. In summary, as compared with fallow in winter without nitrogen application, single application of Chinese milk vetch could significantly increase soil total organic carbon and active organic carbon content. Planting Chinese milk vetch in combination with nitrogen fertilizer applications could significantly increase soil microbial biomass, microbial entropy, and soil carbon pool management index. Among all the treatments, planting Chinese milk vetch in combination with nitrogen-reducing application and conventional-level nitrogen application had better performance.
    Microbial activity analysis during the electrokinetic-bioremediation of resin-contaminated soil.
    WANG Bing, JIA Guang-min, LI Feng-mei, WANG Sa, WU Bo, GUO Shu-hai
    2019, 38(1):  136-144. 
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    Resin, due to its extreme difficulty to be degraded in nature, plays an essential role during the remediation of petroleum-contaminated soil. Resin has high environmental risks since it could accumulate long time in the environment. Functional groups in resin structure such as aromatic nucleus and carboxyl groups are hard to be degraded. Consequently, degradation rate is not enough to indicate the effect of remediation. MicroRespTM method can be used to assess soil community level physiological profiles, which is an important index reflecting the effect of remediation. In this study, resin obtained from Liaohe oilfield and superior mixed bacteria were prepared for the remediation. There were four treatments, including bioremediation (Bio), electrokinetic-bioremediation (EK+Bio1), electrokinetic-bioremediation with nutrient matters (EK+Bio2) and discontinuous electrokinetic-bioremediation (EK+Bio3). The results showed that the average degradation rate varied among different treatments, with an order of EK+Bio2>EK+Bio3>EK+Bio1>Bio. The highest degradation rate was 9.82% (for EK+Bio2), which was 3.06 times of that Bio (3.21%). The abundance of microorganisms increased after remediation, the trend of which was similar to the degradation rate of resin. The results of MicroRespTM analysis showed that the microbial metabolism and microbial activity were promoted. Microorganisms had selectivity of carbon sources under different remediation approaches. The ability of microorganisms to metabolize saccharides substantially increased. In conclusion, electrokinetic-bioremediation could promote the degradation of resin as well as enhance the physiological profiles of soil community.
    Responses of aboveground part of rice to simulated vibration in soil.
    ZHAO Ben-liang, WEN Ting, ZHANG Jia-en, TANG Wei, LIU Jin-ling
    2019, 38(1):  145-152. 
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    In rice-duck farming system, diverse duck behaviours may influence rice growth and the microenvironment. Here, a pot experiment was conducted to clarify the effects of soil vibration that simulated the duck trampling on the aboveground part of Oryza sativa. Four intensities of soil vibrations including 0 (CK), 9 (SV9)，39 (SV39), 90 (SV90) s·d-1·pot-1 were applied for 21 days, using a handmade device to simulate the vibration of duck activities. High intensity of vibration (SV90) significantly reduced leaf surface area and leaf chlorophyll content. The moderate intensity of vibration (SV39) significantly increased soluble protein content. The N contents in the aboveground parts in SV9, SV39 and SV90 treatments increased by 20%, 16% and 12% respectively. The Mg contents in SV9, SV39 and SV90 treatments increased by 25%, 20% and 11%, respectively, while Ca contents increased by 24%, 15% and 8%, respectively. The low intensity of vibration (SV9) increased leaf SOD activity, while both the low intensity and moderate intensity of vibrations increased the leaf POD activities. The moderate intensity of vibration significantly enhanced the leaf CAT activity. The high intensity of vibration significantly increased the content of malondialdehyde in leaves. The low intensity of vibration increased the contents of available N and available P. Our results suggest that soil vibration has significant effects on the morphological and physiological characteristics of the aboveground parts of rice, providing technical parameters for the design of mechanical stimulators to control rice growth.
    Effects of reduction and deep placement of nitrogen fertilizer on rice yield and N2O emissions from double cropping paddy field.
    PENG Shu, ZHANG Wen-zhao, HOU Hai-jun, WANG Hua, CHEN An-lei, WEI Wen-xue
    2019, 38(1):  153-160. 
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    Paddy field is an important N2O emission source. Nitrogen fertilization is one of the main influencing factors for N2O emissions from paddy field. Therefore, it is significant to clarify reasonable nitrogen fertilization to maintain high rice yield and reduce N2O emissions. With the conventional fertilization as control (CF, 150 kg N·hm-2 in the early and late season rice, respectively), three nitrogen application rates (nitrogen fertilizer reduction 30%, 23%, and 16%, respectively) were set up with deep placement to examine the effects of reduction and deep placement of nitrogen fertilizer on rice yield and N2O emissions from double cropping paddy field. The results of a two-year field experiment showed that, through applying chemical fertilizers at a depth of 7 cm in soil,  nitrogen fertilizer reduction 30% significantly increased the numbers of productive ear and grains and increased grain yield by 5%. Reduction and deep placement of nitrogen fertilizer obviously reduced N2O emissions from double cropping paddy field. Compared with CF treatment, nitrogen fertilizer reduction 30% significantly diminished the accumulative emission of N2O by 57% and 72% in the early and late growing season, respectively. In addition, reduction and deep placement of nitrogen fertilizer changed the N2O emission pattern. The N2O emission peak appeared at the tillering stage in the CF treatment, while there was only low N2O emission at the seeding establishment and ripening stages in the treatments with reduction and deep placement of nitrogen fertilizer. In conclusion, rational nitrogen fertilizer reduction combined with deep placement can maintain grain yield and mitigate N2O emissions from double cropping paddy field.
    Effects of different salt stress conditions on growth of sorghum seedlings and function of leaf photosynthetic apparatus.
    ZHANG Hui-hui, LONG Jing-hong, WANG Jun-rui, WU Xu-ye, MA Song-liang, NING Qiang, XU Nan
    2019, 38(1):  161-172. 
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    To clarify the effects of different salt stress conditions on the growth and function of photosynthetic apparatus in Sorghum bicolor seedlings, we evaluated the influences of different Na+ concentrations of two neutral salts (NaCl and Na2SO4) and two alkaline salts (NaHCO3 and Na2CO3) on the seedling growth and functions of photosystem Ⅰ (PSⅠ) and photosystem Ⅱ (PSⅡ) in sorghum variety “Longza No. 17” using hydroponics and simulated salt stress method. The results showed that all the four salt stresses at different concentrations inhibited the growth of sorghum seedlings. The inhibitory effect of the two alkaline salts, especially Na2CO3, was significantly stronger than that of both neutral salts. The neutral salt NaCl had the lowest effect on the growth of sorghum seedlings. The PSⅡ activity in the leaves of sorghum seedlings was inhibited and the maximum PSⅠ redox potential (△I/Io) decreased under all salt stress conditions. The decrease in PSⅡ activity was mainly reflected by the reduction in the activity of oxygen-evolving complex (OEC) on the donor side of PSⅡ and the blockage of electron transfer from QA to QB on the receptor side of PSⅡ. Especially, the donor side was more sensitive to salt stress than the receptor side of PSⅡ. In addition, under the four salt stress conditions, the ability of PSⅡ reaction center to harvest and utilize light was reduced, as well as the concentration of reaction centers (expressed as per unit leaf area) and the ratio of excitation energy to absorb energy. The absorbed- light energy of PSⅡ reaction center was mainly dissipated in the form of heat energy. The effects of the four salt stress conditions on the growth and function of photosynthetic apparatus were in order as follows: Na2CO3>NaHCO3>Na2SO4>NaCl. Therefore, in addition to salt damage, the influence of total alkalinity and the degree of alkalization should be considered while planting sorghum in saline and alkali soils.
    Expression analysis of RbohA andRbohD genes in Brassicacampestris under different treatments.
    ZHANG Teng-guo, LAI Jing, LI Ping, SUN Wan-cang, DIAO Zhi-hong, WANG Juan, ZHENG Sheng
    2019, 38(1):  173-180. 
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    The expression of RbohA and RbohD genes in different tissues of Brassica campestris L. cultivars “Longyou 6” and “Tianyou 2” seedlings under different treatments was detected by realtime fluorescence quantitative PCR. The results showed that RbohAandRbohD genes were expressed in roots, stems, leaves, and hypocotyls of both cultivars without tissue specificity. The expression of RbohA and RbohD was induced by different treatments, including low temperature (2 ℃), salt stress (200 mmol·L-1), and PEG-6000 simulated drought stress. The expression of both genes was higher in “Longyou 6” than in “Tianyou 2”. The expression of RbohA and RbohD genes increased with various degrees in seedlings under exogenous ABA and H2O2 treatments. Compared to the treatment of low temperature or salt stress alone, the expression of RbohA andRbohD was significantly decreased in both cultivars when they were pretreated with DPI (NADPH oxidase inhibitor), U0126 (MPKK specific inhibitor) and DMTU (H2O2 scavenger) with low temperature or salt stress. Such a result indicated that RbohA and RbohD are important for responses to low temperature, salt, and PEG-6000 simulated drought stress. ABA and H2O2 induced the expression of RbohA and RbohD. H2O2 and MAP kinase were involved in the induction of RbohA and RbohD gene expression under low temperature and salt stress.
    Grafting induced the changes of cadmium accumulation in plants.
    GAO Xin, YUAN Hong-hong, SUN Li-zong, GAO Tian-han, WENG Li-ping, TAI Pei-dong
    2019, 38(1):  181-187. 
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    Using wild-type eggplant (Solanum torvum) as rootstock, a field plot experiment was conducted to examine the effects of grafting on Cd accumulation in the shoots of scion plants eggplant (Solanum melongena) and tomato (Solanum lycopersicum). We also explored the role of sulfur in driving plant Cd accumulation. Compared to selfrooted plants, Cd contents in stems, leaves, and fruits of grafted eggplants were reduced by 78.0%, 86.3%, 93.2% in CK, and 89.1%, 89.5%, 92.3% in 2 mg·kg-1 Cdpolluted field plots, respectively. The decreases in grafted tomato plants were 20.6%, 15.5%, 10% in CK, and 79.3%, 48.3%, 4.2% in 2 mg·kg-1 Cd polluted field plots, respectively. Moreover, total sulfur contents in leaves of grafted plants (eggplant and tomato) were significantly reduced, and the trends of which were consistent with Cd accumulation. Our results indicated that specific rootstock induced the changes of Cd accumulation in grafted plants. There was interspecific difference in the responses of plants to the same rootstock. In addition, such changes of Cd accumulation in plants were closely related with the changes of total sulfur content.
    Community structure of crustacean zooplankton and its relationship with environmental factors in two small lakes of Huaibei excavating coal subsidence region.
    YANG Wei, ZHANG Ting-ting, SUN Yu-chen, LIU Qi, GE Qian, DENG Dao-gui
    2019, 38(1):  188-196. 
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    The seasonal dynamics of community structure of crustacean zooplankton in the collapse lakes of Huaibei mining areas (Lake Donghu and Lake Liuqiao) were investigated in April, July, and October 2017 and January 2018. The results showed that a total of 12 species were recorded in two lakes, out of which 8 species (7 genera) belong to cladocera and 4 species (4 genera) belong to copepoda. The annual average density and biomass of crustacean zooplankton in Lake Donghu (12.8 ind·L-1 and 0.26 mg·L-1) were higher than those in Lake Liuqiao (4.4 ind·L-1 and 0.1 mg·L-1). In Lake Donghu, Mesocyclops leuckarti and Diaphanosoma brachyurumwere the dominant species in summer and autumn, whereasCyclops vicinus, Alona quadranyularis, Daphnia galeata, and Chydorus ovalis were the dominant species in winter and spring. In Lake Liuqiao, Bosmina sp., D. brachyurum and M. leuckarti were the dominant species in summer and autumn, whereasA. quadranyularis and C. vicinus were the dominant species in winter and spring. The average values of Shannon index in Lake Donghu and Lake Liuqiao were 0.64±0.27 and 0.93±0.29, respectively. Results from the redundancy analysis showed that water temperature, nutrient concentration (TN and TP), and phytoplankton biomass were main environmental factors affecting the community structure of crustacean zooplankton. The predation pressure of Hypophthalmichthys molitrix and Aristichthys nobilishad an important influence on the seasonal dynamics of crustacean zooplankton community in both lakes.
    The biodiversity and ordination of the plankton community in Maolihu lake by fish community manipulation.
    LIU Fei, YANG Chao, ZHANG Jia-yun, ZHAO Chong, KUANG Wei-qi, CHEN Ke-zhong, LI Meng-jun, LUO Yun-sheng, LIU Liang-guo
    2019, 38(1):  197-204. 
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    The replenishment of fish with different species compositions at the beginning of the year was used to remediate and maintain the ecological environment of Maoli Lake, Changde. We monitored the characteristics of lake plankton and environmental factors in the summer of two years. The effects of fish control measure were analyzed from the aspect of community diversity and ordination. We further discussed the practicability of implementing this technology in lake ecological remediation and maintenance. The mass ratio of silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), block carp (Mylopharyngodon pieces), crucian carp (Carassius auratus) was 15∶60∶15∶10 (by weight) in 2016. The mass proportion of silver carp, bighead carp, block carp, crucian carp, culter fish (Culter aburnus), yellow-head catfish (Pseudobagrus fulvidraco) and mandarin fish (Siniperca chuats) was 25∶50∶10∶5∶5∶3∶2 in 2017. The results showed that water quality of the whole lake was enhanced to the level of Class Ⅲ following environmental quality standards within the two years. The mean chemical oxygen demand (COD) was decreased by 16% from 4.12 mg·L-1 in 2016 to 3.47 mg·L-1 in 2017. The mean levels of transparency, pH, dissolved oxygen, chlorophyll, total nitrogen and total phosphorus of the lake were not significantly changed (P>0.05). The mean density of the phytoplankton was decreased by 4.8% from 518 ×104 ind·L-1 in 2016 to 493×104 ind·L-1 in 2017, while that of the zooplankton was increased by 9.6% from 3283 ind·L-1 in 2016 to 3597 ind·L-1 in 2017. The green algae were dominant, the miniaturization of the zooplankton appeared, and the abundance of the large zooplankton was low. The Margalef indices of phytoplankton, zooplankton and plankton were increased by 6.2%, 15.5%, and 13.6% respectively, while the Shannon index of the zooplankton was increased by 8.3%. Water depth, chlorophyll level and total nitrogen concentration were the key factors controlling the plankton community structure across the two years. The factor weight of COD effect on the community ordination decreased from 0.68 in 2016 to 0.20 in 2017. The COD became the minimum factor affecting community ordination in 2017. The community similarity, plankton population correlation, and the relation of community diversity to environmental factors among nine sites in 2017 weredeclined compared with those in 2016. In all, the fish population manipulation for raising functional group diversity and trophic levels of fish in the lake ecosystem could maintain the lakewater quality to the Class Ⅲ under the national groundwater environmental standards, improve the community diversity, and drive a uniform distribution of plankton species in the lake.
    Visual recognition of carp on invasive species alligator snapping turtle and red-eared slider.
    LIANG Bi-xia, XU Yan-ping, WU Zheng-jun, HUANG Jin-long
    2019, 38(1):  205-209. 
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    Alligator snapping turtle (Macroclemys temmincki) and red-eared slider (Trachemys scripta elegans) are harmful alien invasive species. Both of them have been found in many aquatic ecosystems in China. Here, we examined the antipredation ability of a native species in China, carp (Cyprinus carpio), against those invasive species. By observing whether the carp would try to far away from them during the appearance of alligator snapping turtle and red-eared slider, we estimated the visual recognition ability and anti-predatory behavior of carp. The results showed that when only alligator snapping turtle was present, the carp was able to visually identify the predator within a short period of time (10 min) and stayed away from it. When both invasive species presented simultaneously, the number of carp moving away from alligator snapping turtle was significantly higher than that moving away from red-eared slider at all time points (0-10 min). This may be due to the large range of action, high risk and the fierce movement of the snapping turtle. Our results indicate that the carp can visually identify predators and adopt appropriate survival strategies. Alien invasive species in aquatic ecosystems are harmful to native aquatic organisms. The control of invasive alien species should be strengthened to prevent the release of alien species and reduce their ecological hazards.
    Bacterial community structure and function in the intestinal tracts and culture environment of sea cucumber (Apostichopus japonicus).
    DING Si-yu, WANG Luo, XU Han-chen, BAO Xue-yu, WANG Heng, CHANG Ya-qing, DING Jun
    2019, 38(1):  210-220. 
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    Based on the MiSeq high-throughput sequencing technology, we investigated the structure, α-diversity and function of bacterial community in the intestinal tracts and culture environment of the sea cucumbers (Apostichopus japonicus)  in autumn. The sea cucumbers were cultured in the ponds of the Yellow Sea and Bohai Sea. The results showed that the Chao1 and ACE indices of bacterial community in the bottom sediments of the Yellow Sea and the Bohai Sea were rela-tively high, indicating that the bacterial community in the bottom sediments of the culture ponds was abundant. The dominant bacterial phylum was Proteobacteria (with a proportion of >43.25%) in the intestine of sea cucumbers, pond sediments, and seawater of the Yellow Sea and Bohai Sea. Halioglobus (with a proportion of >12.67%) was the dominant bacterial genus in the intestine of the sea cucumbers in both sea areas. There were differences in the dominant genera in the culture environment. The dominant genus was Roseibacillus (13.59%) in the aquaculture water of the Yellow Sea and Marivita (21.33%) in that of the Bohai Sea. In the aquaculture sediments, the dominant genus was Desulfopila (>9.26%) in Yellow Sea and Thioprofundum (3.79%) in Bohai Sea. In addition, special species belonging to genera Marivita, Ascidiaceihabitans and Aliivibrio were found in the Bohai Sea and accounted for a large proportion. COG and KEGG annotation analysis revealed 24 COG functional groups (primarily serving functions such as amino acid transport and metabolism), and 41 KEGG pathways (mainly representing amino acid transport and metabolism, carbohydrate metabolism, and membrane transport). Our results provide scientific basis for healthy aquaculture of sea cucumber and disease prevention.
    Effects of water depth on chlorophyll content and antioxidant enzyme activity of Hydrilla verticillata.
    LUO Shan-shan, CAO Yun, JI Xin-sheng, XU Ling-ming, WANG Jia-yi, WANG Wen-lin
    2019, 38(1):  221-228. 
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    To clarify the optimal water level for the growth of Hydrilla verticillata and provide theoretical basis for the successful colonization of H. verticillata, we planted H. verticillata in pots with depths of 0.5-1.4 m under water using controlled experiment to examine the influence of water depths on chlorophyll content, antioxidative enzyme activity, malondialdehyde (MDA), and root activity ofH. verticillata. With the increases of water depth, underwater light intensity significantly decreased, whereas chlorophyll a, chlorophyll b, and chlorophyll a+b contents of H. verticillata increased. No significant change was found in chlorophyll a/b, and carotenoid (Car) content increased constantly. Water depth had a significant effect on the antioxidant enzyme activity ofH. verticillata (P<0.05). The activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased first and then decreased. The membrane lipid peroxidation of H. verticillata intensified at the depth of 0.5-0.8 m, which promoted the maximum MDA content and increased the activity of antioxidant enzymes (SOD, POD). When water depth increased from 0.5 m to 1.4 m, there was no significant change of soluble protein content. Root activity increased from 0.12 to 0.51 mg·g-1·h-1, with significant differences among different water depths (P<0.05). Water depth affected the physiology of H.verticillata. The growth and physiology of H.verticillata in the shallow depths (0.5-0.8 m) were strongly inhibited by light availability, manifested as yellow plants, broken branches, residual leaves, reduced chlorophyll content, and increased membrane lipid peroxidation. During the ecological restoration of waters, therefore, a range of 0.9-1.4 m water depth should be considered to restore H.verticillata population, which would facilitate the restoration of aquatic ecosystems.
    Construction of ecological security pattern based on suitability evaluation and minimum cumulative resistance model: A case study of Yingkou City.
    ZHANG Lei, WEI Xiao-jian, ZHOU Peng
    2019, 38(1):  229-236. 
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    Using the combination of “source-corridor” to construct ecological security pattern can maintain regional ecological security and promote human well-being. With Yingkou as a case, ecological sources were selected based on ecological sensitivity and the importance of ecosystem services. The ecological corridor suitability evaluation method and minimum cumulative resistance model were used to identify the potential ecological corridors. The key ecological sources and the important ecological corridors were identified through centrality analysis to construct the ecological security pattern of Yingkou City. The results showed that a total of 134 ecological sources with an area of 2203.88 hm2 were selected in Yingkou. The total length of ecological corridors was 221.06 km. The suitability and important degree of ecological sources and corridors were higher in the southeast and lower in the north, with a large difference between the north and the south. The stepping stone patches and corridors should be constructed in the central and northern parts to promote the material and energy exchange between the north and the south. By putting forward the ecological network framework of “one belt, three regions, three corridors, and multipoints” in Yingkou City, the ecological security pattern was constructed, which would provide references for regional ecological conservation and sustainable development of the city.
    Spatio-temporal variation of cold rain and snow events over South China.
    LU Hong, ZHOU Xiu-hua, HUANG Zhuo, QIN Chuan, NONG Meng-song
    2019, 38(1):  237-246. 
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    We defined and detected the station-based and regional persistent cold rain and snow events over South China (Guangxi and Guangdong) using observation data from 178 stations during 1951-2012, and analyzed their spatiotemporal variation. We aimed to provide a reference for the prediction of cold rain and snow events and for the estimation of the impacts of cold rain and snow events on ecological environment in winter over South China. Station-based events over South China occurred mainly in the north of 23°N, and high-frequency events area mainly concentrated over northeast Guangxi and northwest Guangdong. The regional events mainly occurred in the north of 24°N, and high-frequency events area was similar with the station-based events. The most stationbased and regional persistent cold rain and snow events occurred in January, followed by February. The events were more frequent in the 1970s and 1980s, consistent with the climatic change characteristics of winter temperature over South China. The occurrence of cold rain and snow events was closely related to elevation and terrain. The events occurred more easily in the stations with elevation between 100-200 m. The analysis of the intensity of regional persistent cold rain and snow events using the coldwet index showed that serious events were more frequent in the 1970s. After the 1990s, the serious events tended to be reduced but the severity was more extreme.
    Research advances in seed morphophysiological dormancy.
    YAO Lin-jun, ZHANG Keliang, XIONG Zuo-ming, TAO Jun
    2019, 38(1):  247-255. 
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    Seed morphophysiological dormancy (MPD) is a combination of physiological dormancy (PD) and morphological dormancy (MD), which occurs in seeds with undifferentiated or underdeveloped embryos that are linear, spatulate, or globular in shape. Based on cold and/or warm stratification requirements for germination, temperature requirements for embryo growth, and response to GA3, MPD can be classified into nine types, i.e. non-deep simple, intermediate simple, deep simple, deep simple epicotyl, non-deep simple epicotyl, deep simple double, non-deep complex, intermediate complex and deep complex MPD. The embryo growth and dormancy break are promoted by the same environmental conditions for species, whereas in others they require different conditions. The species that have been reported with MPD are about 34 orders and 72 families. We summarized the morphology of MPD seeds, the environmental conditions required to break MPD, the origin and evolution of MPD, and the species with MPD. Last, we summarized the shortcomings of the previous studies and prospected future researches.
    Research advances in plant symbiotic actinomyces.
    NING Chu-han, LI Wen-bin, LIU Run-jin
    2019, 38(1):  256-266. 
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    Plants are closely related to fungi, bacteria, as well as actinomycetes, constituting a coevolutionary and mutualistic system. There are globally 25 dominant genera of plant symbiotic actinomyces (PSAs), with rich species resources and wide distribution. These PSAs may colonize plant roots, stems and/or leaves to form various symbionts. PSAs can improve plant growth and development through directly or indirectly increasing nutrient and water absorption and utilization, and excretion of plant growth hormones. They can enhance plant stress resistance (such as salt and toxic heavy metal tolerance, and disease resistance) through synthesizing antibiotics and secondary metabolites. Furthermore, they could promote soil health through adjusting soil chemical and physical properties and activating soil nutrients. The development and functions of symbionts between 〖HJ*3〗plants and actinomyces are influenced and regulated by soil conditions, climate factors, geographical characters, and agricultural management strategies. The current status of PSAs application and the problems existing in the current research are also analyzed, aiming to provide theoretical basis and reference for further research and application of PSAs. PSAs are new and unexploited microbial resources with broad application prospect.
    Eco-restoration research progress and strategy about wind-break and sand-fixation forest in Beijing-Tianjin-Hebei Metropolitan Region.
    LIU Shuo, LI Pin, FENG Zhao-zhong
    2019, 38(1):  267-274. 
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    There are serious eco-environmental issues and frequent wind/sand disasters around the Beijing-Tianjin-Hebei Metropolitan Region (Jing-Jin-Ji). Jing-Jin-Ji Dust Storm Sources Control Project is an important ecological construction project in China, with the aim to minimize the sandstorm hazards around the Jing-Jin-Ji. While the project has made some progresses, there are some serious problems during the eco-restoration. The systematical analysis on the constraints to eco-environment and eco-restoration in Jing-Jin-Ji is important to the eco-reconstruction and service function enhancement. Here, we summarized the advances of researches of eco-environment in sandy land, shelterbelt status, vegetation dynamic, tree species selection, and the evaluation of ecological functions in the shelter forests in Jing-Jin-Ji, analyzed the main issues about eco-restoration, and proposed some suggestions to improve the eco-restoration, which could provide effective reference for the vegetation eco-restoration of sandy land in Jing-Jin-Ji.
    Nondestructive diagnosis of total nitrogen content in canopy leaves of Dalbergia odorifera based on multi-features and improved BPNN.
    CHEN Zhu-lin, WANG Xue-feng, CHEN Yi-qing, XUE Yang, LIU Jia-zheng
    2019, 38(1):  275-282. 
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    Nitrogen is one of the indispensable nutritional components for plant growth. Proper fertilization is not only conducive to the healthy growth of plants, but also can reduce the pollution of soil and groundwater. In this study, we proposed a nondestructive diagnosis method of total nitrogen content in canopy leaves of Dalbergia odorifera based on multi-feature and improved BPNN. We divided the canopy image by digital image processing technology, and obtained 27 image features (color, texture, and shape). By calculating the Pearson coefficient, we screened out the factors significantly related to total nitrogen content by principal components analysis. We extracted the first four principal components as the input factors of improved BPNN which was optimized by PSO and Adaboost algorithm (PSO-BPNN-Adaboost). The results showed that the use of multiple features can more comprehensively and accurately reflect the nitrogen content of canopy leaves in Dalbergia odorifera. By comparing BPNN, PSO-BPNN, BPNN-Adaboost and PSO-BPNN-Adaboost, we found that the PSO-BPNN-Adaboost was more reliable and the PSO algorithm had a more optimization effect. Therefore, for the BP neural network, it is necessary to find a suitable initial value and threshold before enhancing them. Our method fully considered the influence of nitrogen stress on plants and outcompeted the traditional method which only considered color factors. Our method provided reference for the precision fertilization in the management of precious trees, which could effectively reduce environmental pollution.
    Accuracy evaluation of different land use or land cover data in grassland of northern China.
    GAO Yan-ni, GUO Yan-fang, WANG Wei, LI Fu-jie, HUANG Pan-pan
    2019, 38(1):  283-293. 
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    Grassland is one of the most widely distributed vegetation types in the world. A precise definition of the grassland boundary is essential for grassland resources research and management. We assessed the boundary accuracy of grassland in northern China, where was characterized by the most concentrated distribution of grassland in China. Based on the grassland sampling point data obtained from field survey, seven kinds of land use/cover data were examined, including the 30m globalland cover data (GlobeLand30), 1∶1000000 grassland resource map (GLT80s), remote sensing monitoring data of land use status in China (LUCC2010), multi-source integrated Chinese land cover map (MICLCover), GlobCover land cover map (Globcover2009), global land use data (GLC2000), and MODIS land cover data (MCD12Q1). The results showed that GLT80s had the largest area of grassland in northern China and was the most consistent with the other six land use/cover data. GLT80s also had the highest accuracy through sampling point verification, with a value of 88.32%. Globcover2009 had the lowest accuracy, with a value of 29.31%. The accuracy of MCD12Q1 and GLC2000 was 83.74% and 83.45%, respectively. The values of other three land use/cover data ranged from 73.42% to 78.97%. Results of statistical analysis for different provinces showed that MCD12Q1 in Qinghai had the highest accuracy(94.23%), and the accuracy of GLC2000 and GlobeLand30 was also above 90% respectively. However, GLT80s always had the highest accuracy in other provinces, including Xinjiang, Tibet, Inner Mongolia, and Gansu. The main reason for the difference of grassland distribution between GLT80s and other data was that the temperate desert grassland in GLT80s was generally classified as bare ground in other data, which occupied 22.59%-42.87% of the total inconsistent distribution area. Therefore, we suggested that MCD12Q1 should be given preference in Qinghai for assessing the grassland resources and function, while GLT80s should be selected in other provinces, but special attention should be paid to the accuracy of its division in temperate desert grassland.
    Retrieval of soil total nitrogen content in reclaimed farmland of mining area based on hyperspectral imaging.
    WANG Shi-dong, SHI Pu-jie, ZHANG He-bing, WANG Xin-chuang
    2019, 38(1):  294-301. 
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    Accurate and rapid estimation of soil total nitrogen (TN) content in reclaimed farmland is the guarantee of land reclamation quality evaluation. Soil samples from reclaimed farmland of Yongcheng mining area were chemically treated and the hyperspectral data were measured indoors. Soil hyperspectral data were transformed by three mathematical methods and then correlated with TN contents, and then the sensitive bands were determined. Subsequently, the partial least squares regression (PLSR) models with BP neural networks (BPNN) and random forest (RF) were combined to establish PLSR-BPNN and PLSR-RF models of inversion of soil TN content based on hyperspectral data. The newly established models were compared with the traditional PLSR, BPNN and RF models. The results showed that the accuracy of the synthetic models (PLSR-BPNN and PLSR-RF) was significantly improved compared to the single model algorithm. In particular, the accuracy of the spectral data processed by the first-order differential method PLSR-BPNN was the highest, with a decision coefficient (R2) of 0.92 and a relative analysis error (RPD) of 4.01. Therefore, the PLS-BPNN model based on the first-order differential spectrum was the best one among the estimation models of soil TN content. The results provide reference for the retrieval of soil TN based on hyperspectral data in reclaimed farmland.
    Scenario analysis on regional energy consumption based on grey model GM(1, 1) and factorization approach: A case study of Liaoning Province.
    JIANG Lu, CHEN Xing-peng, KONG Yun-xiao, ZHANG Zi-long, XUE Bing
    2019, 38(1):  302-308. 
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    As one of the fundamental resources for the survival of human society, energy is an important resource for sustaining economic development and societal progress. Energy consumption is one of the important factors which would trigger climate change and affect the quality of regional environment. Therefore, a situational analysis of regional energy consumption is important for controlling the overall energy consumption and making a reasonable regional energy policy. Taking Liaoning, an old industrial base in Northeastern China, as an example, we used the method of grey relational analysis to quantitatively analyze the correlation of energy consumption and economic growth between 2000 and 2014. The degree of correlation was 0.93, suggesting an energy driven model of development. Based on grey model GM(1, 1), we conducted a situational analysis of expected energy consumption between 2015 and 2029. The results showed that the secondary industry would consume the greatest amount of energy. The consumption would show an exponentially rising trend. Based on the factoring method as well as energy saving index, we evaluated the potential and efficiency of regional energy conservancy. We concluded that regional energy conservancy should be structural energy conservancy and technology-based energy conservancy. We proposed recommendations towards sustainable transition of energy.