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    10 July 2021, Volume 40 Issue 7
    Response of plant community characteristics to precipitation change in desert steppe from a monthly-scale perspective.
    GUO Ya-fei, ZHANG Li-hua, ZHAO Rui-feng, XIE Zhong-kui, WANG Jun-feng, HAO Lian-yi, GAO Jiang-ping, WANG Meng-meng, GAO Han
    2021, 40(7):  1895-1906.  doi:DOI: 10.13292/j.1000-4890.202107.002
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    Precipitation is one of the most important water sources in semi-arid desert steppe. The changes of rainfall in growing season directly affect plant growth, interspecific relationship, and thus the structure and function of plant community. In this study, a three-year rainfall manipulation experiment (-40%, -20%, 0 (CK), +20%, +40% rainfall in growing season) was carried out in the desert steppe in the west of the Loess Plateau, to explore the effects of precipitation change on density, height, coverage, functional type composition, the importance value of dominant species, and species diversity of plant communities from the perspective of monthly scale. It was found that: (1) compared with the increasing rainfall treatments, there were significant effects of extreme reducing rainfall (-40%) on the density, height and coverage of plant communities (P<0.05), with such effects being significantly stronger in the middle and late growing season (July, August and September) than in the early growing season (May and June). The rainfall in July and August was the key factor driving plant growth in the semiarid area. (2) Extreme rainfall reduction altered plant community structure by increasing the importance value of Stipa brevifloraand decreasing that of Ajania fruticulosa. Extreme rainfall reduction increased the dominance of Gramineae species. (3) The threeyear extreme rainfall reduction decreased plant species richness and diversity, which was not conducive to the stability of plant community. However, the continuous extreme rainfall increasing treatment (+40%) resulted in higher species richness than other treatments, and had significant difference with the precipitation reduction treatments (P<0.05). Under the scenario of changes in precipitation regime, more real-time management of desert steppe in different periods during the growing season is of great significance for vegetation protection and stability maintenance in ecologically sensitive areas.
    Assessing the impacts of nitrogen deposition on poplar plantation based on Gaofen and Sentinel imagery.
    WANG Hao-bin, PU Yi-han, XU Dan-dan
    2021, 40(7):  1907-1915.  doi:DOI: 10.13292/j.1000-4890.202107.018
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    Nitrogen deposition has multiple effects on forest ecosystems. Previous related studies mainly focused on immediate effects in the short term. It is critically needed to study long-term impacts of nitrogen deposition on forest ecosystems. To understand the effects of nitrogen deposition with different levels on forest ecosystem, a simulated nitrogen deposition experiment was conducted in a 8-year-old poplar (Populus deltoides) plantation since 2012, with the treatments of CK (0 kg·hm-2·a-1), low nitrogen deposition (N1, 50 kg·hm-2·a-1), medium nitrogen deposition (N2, 100 kg·hm-2·a-1), high nitrogen deposition (N3, 150 kg·hm-2·a-1), and ultrahigh nitrogen deposition (N4, 300 kg·hm-2·a-1). The effects of nitrogen addition on the growth of poplar plantation over long time series was examined using Gaofen (GF1, GF2) and Sentinel (Sentinel-2) satellite images by extracting poplar NDVI values. The results showed that the NDVI values of poplar trees were increased by 2.0%, 4.8%, 4.3%, and 4.5% in the four N treatments, respectively. The maximum growth rate occurred after treated for two years. After four years of treatment, the NDVI values of poplar trees under nitrogen addition were all greater than that of the CK, which indicated that nitrogen deposition had positive effects on poplar growth. However, such promotion effects were overall weakened after three years. After being treated for six years, medium and low nitrogen deposition had a promoting effect on poplar growth, but high and ultrahigh nitrogen treatment had an inhibiting effect. Overall, the promoting effect was gradually weakened while the inhibiting effect was gradually enhanced with increasing nitrogen addition levels.
    Effects of soil and air warming on fine root biomass and leaf traits of Chinese fir saplings.  
    SHI Ying-gui, XIONG De-cheng, YE Wang-min, ZHANG Nan, TANG Yu-xiang, CHEN Juan, WU Fan, LIU Xiao-fei, YANG Zhi-jie
    2021, 40(7):  1916-1923.  doi:DOI: 10.13292/j.1000-4890.202107.014
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    To reveal the effects of different warming modes on the fine root biomass and leaf traits of Chinese fir saplings, an experiment with factorial soil warming (ambient, +4 ℃ via cable heating) × air warming (ambient, opentop chamber (OTC)) was carried out in Sanming, Fujian Province. The results showed that the total fine root biomass of Chinese fir significantly reduced in the air warming treatment and the soil + air warming treatment compared to the control, whereas the total fine root biomass was not reduced by soil warming. Fine root biomass was significantly reduced in 0-10 cm soil layer under all the warming treatments, and was significantly reduced in 10-20 cm soil layer in the air warming treatment and the soil + air warming treatment. The biomass of fine roots in 20-40 cm soil layer did not differ among all the treatments. Leaf tissue density (LTD) and leaf mass per area (LMA) of 1-year-old leaf were significantly reduced in the soil warming treatment and the air warming treatment, while LTD and LMA of 2-year-old leaf were significantly increased in the soil warming treatment and the soil + air warming treatment. The leaf area of 2-year-old leaf was significantly reduced in the air warming treatment, the soil warming treatment, and the soil + air warming treatment. Our results suggest that Chinese fir saplings may adapt to the increased temperature by changing vertical distribution of fine root biomass in soils and leaf traits of different leaf ages. In order to reveal the effects of warming on plants more truly and accurately, the effects of different warming methods on plant traits should be considered, especially the control experiments of simultaneous warming above and below ground should be strengthened.
    The yield and quality formation characteristics of passion fruit and their response to meteorological factors in Guangxi, China.
    TIAN Qing-lan, WU Yan-yan, LIU Jie-yun, HUANG Wei-hua, MOU Hai-fei, ZHANG Ying-jun, WEI Shao-long, WEI Di
    2021, 40(7):  1924-1936.  doi:DOI: 10.13292/j.1000-4890.202107.020
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    To understand the yield and quality formation characteristics of passion fruit and their response to meteorological factors in Guangxi, we investigated the yield and yield components of ‘Tainong No. 1’, the main variety of passion fruit in China. We determined the fruit quality of different branches ripening in the same period and fruit quality of the same branches ripening in different periods. We further analyzed the relationships between quality characters and meteorological factors during flowing to fruit ripening stage by correlation analysis and regression analysis. The yield per unit area was 11.65 t·hm-2. The secondary lateral vine and primary lateral vine were the main yield components, with a contribution of 58.2% and 24.2%, respectively. The harvest time of the fruit was 91-186 days after transplanting. The fruit ripening time ranged from 43 to 165 days. Fruit morphology and single fruit weight were not affected by the ripening time. Fruit quality among different branches in the same harvest time differed in pulp weight, titratable acid content, and peel thickness. For the quality of fruit harvested in different growing seasons of the same branch, pulp weight and juice yield increased with the growth delay and the increasing ripening time. Pulp weight and juice yield began to decrease when the ripening time was longer than 125.6 and 141.6 days, respectively. The soluble solid content and peel thickness decreased from January of the following year. Except the maximum relative humidity, temperature and light intensity in the ripening stage of fruit were significantly negatively correlated with pulp weight and juice yield, while the relative humidity was significantly positively correlated with pulp weight and juice yield. The pulp weight (>35 g) and juice yield (>45%) of ‘Tainong No. 1’ were relatively high under the conditions of 16.1-18.7 ℃ for daily average temperature from flowering to maturity, 2.8×103-3.2×103 lx for daily average light intensity, and 88.0%-89.4% for the daily average relative humidity.
    The effects of rainfall partitioning on heavy metal deposition for three typical urban tree species in Guangzhou.
    CHEN Xiao-ying, ZHI Qiu-ying, YANG Xiao, JIANG Zhi-yun, XIE Ru-chen, GU Yuan-mei, ZENG Yi-hong, ZENG Da, SUN Sheng-sheng, HUANG Rui-bin, XIAO Yi-hua
    2021, 40(7):  1937-1946.  doi:DOI: 10.13292/j.1000-4890.202107.006
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    Rainfall partitioning has great effects on chemical elements transport. We examined the effects of rainfall partitioning on the deposition of heavy metals (Zn, Fe, Cu, Ni, Pb, As, Cd and Hg) for three typical urban tree species (Roystonea regia, Ficus microcarpa and Lagerstroemiaspeciosa) in Guangzhou from October 2018 to September 2019. Results showed that the rate of throughfall to precipitation for R. regia, F. microcarpa and L. speciosawas 62.68%, 58.79% and 67.95%, respectively, while the stemflow rate was 6.34%, 2.08% and 1.02%, respectively. These results suggest different rainfall partitioning among three urban tree species. Except that Cd leaching coefficient of F. microcarpa stemflow was less than 1, the leaching coefficients of heavy metals for throughfall and stemflow of three species were greater than 1, indicating positive leaching. The total inputs of heavy metals for three urban trees were 1.11, 1.80 and 1.99 times of that from precipitation, indicating that the contents of heavy metals were increased after precipitation. The enrichment rate of heavy metals for stemflow ranged from 2.06 to 118.22, suggesting that stemflow could enrich heavy metals in urban trees. The results have important implications for the selection of urban tree species and the prevention of regional pollution.
    Radial growth responses of four typical coniferous species to climatic factors in the Western Sichuan Plateau, China.
    ZHANG Meng, SHI Song-lin, SHI Chun-ming, BAI Hai, LI Zong-shan, PENG Pei-hao
    2021, 40(7):  1947-1957.  doi:DOI: 10.13292/j.1000-4890.202107.015
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    To reveal the growth responses of different coniferous species to climatic factors in the southeastern Tibetan Plateau, we used dendrochronological techniques to sample tree-ring cores of the dominant species of alpine coniferous forest in Daofu County, western Sichuan Province, including Abies squamata, Picea likiangensis var. rubescens, Juniperus saltuaria, and Larix potaninii. We developed treering width chronologies of the four species and conducted growth-climate relationship analyses to understand the influence of climatic factors on tree radial growth. The results showed that tree growth responses to climatic factors differed among the four species. The radial growth of A. squamata and L. potaniniiwas significantly positively associated with mean minimum temperature (Tmin) during most of the months in previous and current years, while the growth of P. likiangensis var. rubescens and J. saltuaria was not significantly correlated withTmin. Furthermore, relative humidity had strong limiting effect on the radial growth of P. likiangensis var. rubescens from previous October to current March, but had little influence on the growth of other three conifers. Since 1958, the relationship between the growth of A.squamataand the Tmin in growing season (June to August) has remained stable, the relationship of radial growth of L. potaniniiandP. likiangensis var.rubescens with theTmin in growing season decreased first and then increased, while the association between J.saltuaria radial growth and growing season Tmin has gradually decreased. Those results suggest that climate warming could benefit the development of A. squamata, L. potaninii and P. likiangensis var.rubescens and enhance tree radial growth, but weakly influence the radial growth of J. saltuaria, which may potentially affect stand structure and composition of alpine coniferous forest in this area.
    Adaptation of leaf anatomical structure and stoichiometric characteristics of wild ancient tea tree to different altitudes in Qianjiazhai.
    WANG Fei, CHENG Xiao-mao, XIAOYun-long, HUANG Xiao-xia
    2021, 40(7):  1958-1968.  doi:DOI: 10.13292/j.1000-4890.202107.034
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    We compared leaf anatomical structure, carbon (C), nitrogen (N) and phosphorus (P) concentration and their stoichiometry of wild ancient tea trees (Camellia talinensis) along an altitudinal gradient (2050, 2200, 2350, 2500 m) of Qianjiazhai Reserve in Ailao Mountain to clarify the response and adaptation of tea trees to environmental changes. The results showed that the thickness of leaf and diverse tissues (epidermis, cuticle, palisade tissue, sponge tissue, main vein) and C concentration showed a uni-modal pattern with rising altitude and peaked at altitude of 2200 m, suggesting that the environment at 2200 m altitude was conducive to the wild ancient tea trees for carbon assimilation, growth, and metabolism. The leaf structure became more compact and the concentrations of C, N and P in leaves showed a trend of increase, which would help tea trees adapt to the environment at high altitude. The anatomical indices showed a medium variation and exhibited high plasticity across the altitudinal gradient. Moreover, the growth of wild ancient tea trees in this region was not limited by N and P availability. The differences in either anatomical structure or stoichiometry of wild ancient tea trees across the altitudinal gradient might play a significant role in adapting to the vertical gradient niche.
    Changes of non-structural carbohydrates of Populus × xiaozhuanica cv. Zhangwu seedlings during process of natural drought.
    WANG Kai, PANG Ying-ying, LYU Lin-you, ZHANG Da-peng, JIAO Xiang-li
    2021, 40(7):  1969-1978.  doi:DOI: 10.13292/j.1000-4890.202107.038
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    In order to understand the changes of non-structural carbohydrates (NSC) in Populus× xiaozhuanica cv. Zhangwu seedlings under drought stress, we analyzed leaf water potential and contents of NSC, soluble sugar, and starch in different organs (leaf, stem, and root) with intensified drought conditions. The results showed that the contents of NSC and soluble sugar in leaves and roots increased, and starch content and water potential in leaves and soluble sugar content in stems decreased when soil water content dropped from 100% to 84% of field waterholding capacity. NSC contents in leaves and stems decreased and the ratio of soluble sugar to starch in stems and roots increased, while leaf water potential increased at predawn and decreased at midday when soil water content dropped from 84% to 41% of field water holding capacity. Leaf NSC content and water potential, stem NSC content, and root soluble sugar content increased, while leaf and root starch contents decreased when soil water content dropped from 41% to 31% of field water holding capacity. NSC and starch contents in leaves and stems, and leaf soluble sugar content and water potential decreased, whereas root NSC contentincreased when soil water content dropped from 31% to 20% of field water-holding capacity. Contents of NSC, soluble sugar and starch in leaves and stems increased, whereas root NSC content and ratio of soluble sugar to starch, and leaf water potential decreased when soil water content dropped from 20% to 16% of field waterholding capacity. Our results indicated that P. ×xiaozhuanica cv. Zhangwu seedlings would decrease leaf carbon storage but increase root carbon distribution and carbon consumption under natural drought. When hydraulic imbalance limits carbon transport and metabolism, seedlings may die due to root carbon starvation.
    Seed germination of an invasive species Iva xanthiifolia.
    WANG Li-Juan, LI Ai-Yu, FENG Xu, WU Jia-Wen, WANG Xue, LIU Dan, LI Cui-Ting, XU Yong-Qing
    2021, 40(7):  1979-1987.  doi:DOI: 10.13292/j.1000-4890.202107.024
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    Iva xanthiifolia is an alien invasive plant species, with serious threat to biodiversity in Northeast China. In this study, we measured the 1000grain weight, water content, germination indices and endogenous gibberellin levels of seeds collected in different years. To elucidate the germination characteristics of Iva xanthiifolia seeds and their roles in invasion, we explored the effects of photoperiod, cold stratification time, and freezing stress on seed germination and seedling growth with seeds collected in 2019. Results showed that the 1000-grain weight of seeds collected in different years was 1.172-1.311 g, water content was 0.93%-1.26%, and germination rate and endogenous gibberellin content were decreased significantly with the increasing storage time. Iva xanthiifolia seeds required light for germination. The germination rate tended to increase significantly with the duration of light exposure. However, light treatment significantly inhibited seedling hypocotyl elongation. With the time extension of cold stratification at 4 ℃, there was an initial increase and then a decreasing trend for seed germination characteristics. The highest germination rate of 68.3% was obtained after 15 d of treatment. Germination rate, endogenous gibberellin content of seeds, fresh weight of seedlings were significantly reduced by freezing treatment at -20 ℃ and -40 ℃, but the hypocotyl length of seedlings was not significantly affected. Our results showed that deep ploughing before sowing would be an effective measure for field control of Iva xanthiifolia.
    Altitudinal variations of leaf functional traits of Rhododendron simsii and Pinus taiwanensis in Wuyi Mountain, Jiangxi.
    LAI Yuan, ZHANG Ling-ling, GUO Ying-rong, LEI Ping, REN Wen-dan, LIU Zhan-feng, KUANG Yuan-wen
    2021, 40(7):  1988-1996.  doi:DOI: 10.13292/j.1000-4890.202107.023
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    Understanding the variation of leaf functional traits of plant species from different elevations provides basis for assessing the adaptive strategies of plants and predicting the potential shifts in plant species distribution, community dynamic, and forest ecosystem structure and function under climate changes. In this study, we quantified the variations in leaf traits of two species (Rhododendron simsii and Pinus taiwanensis) commonly growing at three elevations (>1900, 1500-1700, 1000-1300 m above sea level) in Wuyi Mountain National Nature Reserve in Jiangxi Province. Leaf traits related to defence (i.e.,concentrations of lipids, lignin, soluble phenolics, organic acids, total nonstructural carbohydrates, total structural carbohydrates), traits related to growth (i.e., specific leaf area, concentrations of protein, minerals, carbon (C), nitrogen (N), phosphorus (P), and N/P ratio), and leaf construction costs (CC) were compared for species from different elevations. Correlations among the different leaf traits were also examined. The results showed that 
    leaf CC of both species did not vary significantly among the elevations. The concentrations of soluble phenolics  in leaves of both species significantly decreased with elevation, while foliar protein, N and P concentrations increased. With increasing elevation, lignin concentrations in leaves of R. simsii decreased, whereas the concentrations of total structural carbohydrates and minerals in leaves of R. simsi and the concentration of total nonstructural carbohydrates in leaves of P. taiwanensis increased. Leaf CC of R. simsii was negatively correlated with the concentrations of organic acids and minerals and specific leaf area, and positively correlated with the concentration of total nonstructural carbohydrates. Leaf CC of P. taiwanensis was positively correlated with the concentration of soluble phenolics. The concentration of leaf protein was positively correlated with the concentration of leaf total structural carbohydrates in R. simsii, and positively correlated with the concentration of leaf nonstructural carbohydrates in P. taiwanensis. The variations of leaf functional traits related to growth and defence across the altitudinal gradient indicate that both species could adapt to environmental change.
    Differences in clonal growth and photosynthetic physiology between Populus euphratica Oliv. and Populus pruinosa Schrenk.
    LI Xiu, CHEN Xiang-xiang, ZHAI Jun-tuan, LI Zhi-jun
    2021, 40(7):  1997-2004.  doi:DOI: 10.13292/j.1000-4890.202107.019
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    We compared the interspecific and intraspecific clonal growth and photosynthetic physiology ofPopulus euphraticaOliv. and Populus pruinosa Schrenk in the mixed forest in different groundwater-level habitats in Alar, Xinjiang, China. Under the same habitat, Populus euphraticaand Populus pruinosa differed in leaf area and dry weight of ramets. The leaf area and leaf dry weight of Populus pruinosa were significantly higher than those of Populus euphratica, while the net photosynthetic rate, stomatal conductance, transpiration rate and CO2 utilization efficiency of the ramets of Populus pruinosa were significantly higher than those of Populus euphratica. Across different habitats, basal diameter, plant height, leaf number, leaf area, stem dry weight and leaf dry weight of each clump of the ramets of both species were significantly higher in the habitat of 1.5 m groundwater level than in the habitat of 2.6 m groundwater level, whereas the number of branches per clump and the specific leaf area were opposite. The stomatal conductance, intercellular CO2 concentration, net photosynthetic rate, and water use efficiency of Populus euphratica ramets in the habitat with low groundwater level were significantly higher than those in the habitat with high groundwater level. Collectively, under the same habitats, Populus pruinosa ramets had a stronger ability to acquire light resources than Populus euphratica ramets. Under different habitats, the differences in the growth and photosynthetic physiological characteristics in both Populus euphratica and Populus pruinosa ramets were related to groundwater depth.
    Effects of exogenous abscisic acid (ABA)on the growth, stomatal traits, and photosynthesis of maize seedlings under NaCl stress.
    ZHANG Hao, WU Zi-long, FU Wei, YE Jia, MA Jie, HAO Li-hua, CHANG Zhi-jie, ZHENG Yun-pu
    2021, 40(7):  2005-2015.  doi:DOI: 10.13292/j.1000-4890.202107.028
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    We explored the effects of different concentrations of abscisic acid (ABA; 0, 1, 2.5, 5, 10 μmol·L-1) on the growth characteristics, stomatal morphology, photosynthesis of maize seedlings (Jingke 665) under NaCl stress (100 mmol·L-1), with the treatment without NaCl solution and ABA as the control. The results showed that exogenous ABA increased plant height, leaf length, root/shoot ratio, aboveground biomass, and total biomass of maize under salt stress (P<0.01). Both stomatal width (P=0.001) and area (P<0.001) on the adaxial surface were decreased, while the width (P=0.001) and area (P=0.012) of the stomata on the abaxial surface reached the maximum at the concentration of 5 μmol·L-1. Exogenous ABA reduced the L(d) values of stomatal spatial distribution on the abaxial leaf surface than those under salt stress, suggesting exogenous ABA could make the stomatal spatial distribution more regular than those plants under salt stress. The application of ABA released the decline of Pn, Tr, Gs, Ciand WUE of maize leaves under salt stress, and increased the contents of chlorophyll a, chlorophyll b, and total chlorophyll (P<0.01). In addition, exogenous ABA decreased the relative conductivity (P=0.002) and increased the Fv/Fm value (P<0.001). These results indicate that exogenous ABA could optimize gas exchange process by adjusting the stomatal morphological characteristics and spatial distribution pattern of stomata, and alleviate the physiological stress on the growth and development of maize under NaCl stress.
    Identification of the cadmium transport gene ZmNramp1 in maize and its response to cadmium stress.
    LI Ya-min, GONG Zong-qiang, JIA Chun-yun, LI Xiao-jun, LIU Wan
    2021, 40(7):  2016-2023.  doi:DOI: 10.13292/j.1000-4890.202107.011
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    NRAMP (natural-resistance-associated macrophage) protein family plays an important role in the regulation of heavy metal cadmium (Cd) uptake and transport in plants. Based on conserved sequences of Nramp1 genes from Arabidopsis, rice, tomato and Malus baccata, we designed the degenerate oligonucleotideprimers of the maize Nramp gene. The length of ZmNramp gene identified by cloning and sequencing was 314 bp with 10 exons and encoding 104 amino acids and this gene was named asZmNramp1. By comparing the sequences of Nramp1 gene fragments and amino acids of the above chosen plants, we found that they have the same conserved domains and highly similar oligonucleotide sequences. Bioinformatics analysis results showed that ZmNRAMP1 had molecular weight of 11.5 kD, theoretical pI (protein isoelectric point) of 6.92 and typical transmembrane helical region of transmembrane protein. The RTPCR (reversal transcript polymerase chain reaction) results indicated that the expression of ZmNramp1 gene was significantly up-regulated in the maize seeding roots and leaves treated with different concentrations of cadmium (50, 100 μmol·L-1 CdCl2) for 24 h, which was increased by 57% and 83% in roots, and by 26% and 50% in leaves (P<0.05). There was a significantly positive relationship between ZmNramp1 gene expression and Cd content in the seeding roots and leaves of maize, which indicated that the ZmNramp1 gene may be involved in Cd absorption and transportation in maize. Our results provide theoretical basis and genetic resources for maize breeding for heavy metal resistance.
    Responses of dry matter accumulation, nitrogen utilization and yield of table corn to new slow-release fertilizers.
    XIE Ting-ting, ZHAO Huan, XIAO Hou-jun, CHEN Yun-mei, QIN Song, HU Gang
    2021, 40(7):  2024-2032.  doi:DOI: 10.13292/j.1000-4890.202107.027
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    To screen a new slow-release fertilizer suitable for table corn planting in yellow soil area of Guizhou, a pot experiment was conducted to examine the effects of different new slow-release fertilizers on dry matter accumulation, biological traits, total nitrogen accumulation, photosynthetic characteristics, nitrogen use efficiency, yield and yield components of table corn, with four treatments of no N (T1), conventional fertilization (T2), coated slow-release fertilizer (T3) and stable slow-release fertilizer (T4). Results showed that both slowrelease fertilizers improved corn yield. The coated slow release fertilizer got the highest yield, reaching 65.31 g·plant-1. In the corn harvest period, dry matter accumulation of table corn with coated slowrelease fertilizer was the highest (127.89 g·plant-1), being significantly higher than that of another new slow release fertilizer. Plant height and stem diameter of table corn followed the sequence of stable slowrelease fertilizer > coated slowrelease fertilizer. The ear height and chlorophyll presented as coated slowrelease fertilizer > stable slowrelease fertilizer. The difference between the two slowrelease fertilizers was not significant. Except for 100kernel weight, the application of coated slowrelease fertilizer was the best for all yield components. The total nitrogen accumulation of corn gradually transferred from leaf and stem to grain along with growth period. The coated slowrelease fertilizer treatment got the highest in the harvest period, accounting for 58.2% of the whole plant. Nitrogen agronomic efficiency, partial productivity and apparent utilization rate were the highest in coated slow-release fertilizer treatment, which were 13.73 g·g-1, 17.42 g·g-1, and 68.49%, respectively. There was no significant difference between the two new slow-release fertilizers. The application of new slowrelease fertilizers significantly improved the photosynthetic characteristics of table corn, with Pn, Tr and Gs reached the peak at jointing stage. In conclusion, coatedslow release fertilizer had positive effects on dry matter accumulation, biological characters, yield components, photosynthetic characteristics, total nitrogen accumulation, fertilizer utilization rate, and yield of table corn. Therefore, coated slow-release fertilizer is suitable for high yielding cultivation of table corn in Guizhou yellow soil area.
    Influence of biocrusts succession process on bacterial community structure of biocrustal layer and subsoils in desert steppe.
    FAN Jin, LI Shi-yao, WANG Rong-rong, YU Hai-long, HUANG Ju-ying
    2021, 40(7):  2033-2044.  doi:DOI: 10.13292/j.1000-4890.202107.012
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    To verify the effects of different biological soil crusts (biocrusts) succession phases (algal crusts, mixed crusts, moss crusts) on microbial community compositions and diversities in biocrustal layer and subsoils in a desert steppe, Ningxia, China, the biocrusts and subsoils (0-5 cm) were sampled using method of space instead of time series. The highthroughput sequencing of V3-V4 fragment of bacterial 16S rRNA was conducted using the platform of Illumina Miseq. The bacterial α and β diversity, community structure and their relationships with soil physical and chemical factors were analyzed. The results showed that bacterial α diversity showed a consistent trend. The Chao1, ACE and Shannon indices in the subsoil (0-5 cm) were all higher than those of biocrustal layer (P<0.05), while α diversity among biocrusts was not significant (P>0.05). Results of principal coordinate analysis results indicated that 0-5 cm soil beneath different biocrusts had similar bacterial OTUs, and could be categorized as one type. Bacterial community structures of algal crust and mixed crust had some similarity, but that under moss crust was significantly different from algal crust and mixed crust. The dominant bacteria community of three biocrusts and subsoils were consistent. The topfive dominant bacterial community phyla were Actinobacteria, Proteobacteria, Acidobacteria, Gemmatimonadetes, and Planctomycetes. The relative abundance of these dominant bacterial communities in subsoil (0-5 cm) were higher than that in biocrustal layer, and that of the endemic and shared genera was higher in subsoil (0-5 cm) than in biocrustal layer. Results of distance based redundancy analysis (db-RDA) indicated that soil available potassium, total nitrogen and soil available phosphorus concentrations were the main factors affecting soil bacterial community structure in biocrustal layer, and explained 21.4%, 18.9% and 17.4% variances (P<0.05), respectively, whereas EC was the major factor affecting soil bacterial community structure in subsoil (0-5 cm), and explained 20.5% of variance (P<0.05). These results suggested that the development of soil microorganisms and the improvement of soil physical and chemical properties were inter-dependent, and that the changes of bacterial community structure and diversity facilitate the improvement of physical and chemical properties of biocrustal layer during the process of biocrusts succession.
    Soil bacterial community diversity and carbon source metabolism function in walnut orchard with different stand ages.
    GU Mei-ying, XU Wan-li, MA Kai, FENG Lei, ZHANG Zhi-dong, OUTIKUER·Mahmut, ZHU Jing, TANG Guang-mu, TANG Qi-yong, CHU Min
    2021, 40(7):  2045-2056.  doi:DOI: 10.13292/j.1000-4890.202107.030
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    To understand the variation of bacterial communities in soils of walnut orchard with different planting years, we measured soil bacterial community diversity and carbon source metabolism function in the surface (0-20 cm) and subsurface (20-40 cm) layers of walnut orchard with different planting years (1-3, 5, 8-10, 15 and 20-25 years) by using highthroughputsequencing and Biolog ECO microplate. The correlations between diversities of bacterial community〖JP〗 and carbon source metabolism function with soil physicochemical properties were analyzed. The results of highthroughput sequencing showed that bacterial communities showed surface accumulation in soils. After five years of planting, the number of OTUs and diversity indices in surface layer were higher than that in subsurface layer. Proteobacteria, Acidobacteria, Actinomycetes, and Chloroflexi were the dominant bacteria phyla. With the extension of planting years, the relative abundance in different soil layers showed a tendency of increasing first and then decreasing. The relative abundance of clearly classified dominant genera in soil of 10 years planting was the highest. Biolog analysis results showed that bacterial activities in the surface layer were significantly lower than those in the subsurface layer. With the extension of planting years, bacterial activities and Shannon diversity index increased first and then decreased. Orchard with 8-10 years and 15 years planting history had the highest bacterial metabolic activities and diversities. The utilization of amino acids and polymers by surface soil bacteria increased gradually, while the utilization of other carbon sources increased first and then decreased. In subsurface layer, the utilization of all carbon sources decreased except phenolic acids. There were negative correlations between Shannon diversity index and physicochemical properties of surface layer, and positive correlations between Simpson diversity index and physicochemical properties. Total salt content, pH and nutrients were the main factors affecting the bacterial diversities of surface layer. The diversities of bacterial community and utilization of carbon sources in different soil layers of walnut orchard with planting for 1-3 years and 20-25 years were obviously low, which exacerbated the imbalance of soil microenvironment. Manures or biofertilizers should be added to improve soil microenvironment of walnut orchards.
    Bacterial community structures in the root-associated soil of four tree species in the Greater Xing’an Mountains.
    2021, 40(7):  2057-2066.  doi:DOI: 10.13292/j.1000-4890.202107.008
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    The aim of this study was to clarify soil bacterial diversity and community structure in cold temperate forest ecosystem and their response to soil physicochemical properties. The root associatedbacterial community structure and diversity in the rhizosphere of Betula platyphylla, Pinus sylvestrisvar.mongolica, Larix gmelinii and Pinus pumilain Genhe were investigated with Illumina highthroughput sequencing technology. The key environmental factors affecting the bacterial community structure were analyzed. The results showed that bacteria in the rootassociated soil of four tree species from 20 phyla, 63 classes, 127 orders, 225 families, and 371 genera were detected. There were 10 bacterial phyla with relative abundance greater than 1.0%. Proteobacteria, Acidobacteria and Actinobacteria were the predominant bacteria, with a total relative abundance of more than 75.0%. The richness and evenness of rootassociated bacteria of P. sylvestris var.mongolica were  the highest. Results of Pearson correlation analysis showed that bacterial diversity and abundance were significantly affected by soil physicochemical properties. RDA was used to analyze the contribution rates of soil physicochemical factors to the formation of bacterial community structure. All the factors explained 94.0% of bacterial community variation. Among them, pH had an extremely significant effect on the distribution of bacteria, with an explanation degree of 70.1% (P<0.01), followed by nitrate concentration, with an explanation degree of 6.9% (P<0.05). Our results provide a basis for understanding the structure and function of soil microorganisms in the cold temperate forest.
    Responses of phenolic acids accumulation in the rhizosphere soil of Robinia pseudoacacia L. seedlings to the combination of elevated atmospheric CO2 and Cd exposure.
    WANG Zi-wei, JIA Xia, YAN Zhan-kuan, CAO Ke-meng, ZHANG Chun-yan, WANG Lu, ZHANG Ning-jing, GAO Yun-feng
    2021, 40(7):  2067-2075.  doi:DOI: 10.13292/j.1000-4890.202107.037
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     Phenolic acids in rhizosphere soils are mainly derived from root exudates, litter, and the decomposition of soil humus. They play an important role in the formation and stability of organic and organicinorganic composite colloids, the activation and transformation of heavy metals in soils, and the growth and metabolism of microorganisms. Here, we investigated the effects of elevated CO2 \[(750±31)umol·L-1\] on the accumulation of phenolic acids in the rhizosphere soil of Robinia pseudoacacia L. seedlings exposed to different Cd levels (0, 0.45, and 4.5 mg·kg-1 dry weight soil). Elevated CO2, Cd level, seedling growth time, and their interaction had significant effects on the accumulation of phenolic acids in the rhizosphere soil. Elevated CO2 enhanced the contents of hydroxybenzoic acid, caffeic acid and pcoumaric acid in the rhizosphere soil of R.pseudoacacia seedlings exposed to Cd (P<0.05). The responses of gallic acid to the combined treatments were different from that of the three phenolic acids. Under the combined treatment relative to Cd exposure alone, the content of gallic acid increased at day 45 (P<0.05), decreased at day 90 (P<0.05), and was not detected at day 135. The content of total phenolic acids increased under the combined treatment relative to Cd exposure alone at day 90 (P<0.05). The results of Pearson correlation analysis and redundancy analysis showed that root biomass, root C content, root Cd accumulation, and soil Cd content affected the content of phenolic acids in rhizosphere soils.

    Effects of nitrogen deposition and its coupling with exogenous nutrients and carbon sources on soil carbon and nitrogen transformation in Cunninghamia lanceolata plantations at the later stage of treatments.
    ZHENG Qi, WANG Xiao-dong, BU Wen-sheng, LIU Bin, YUAN Ping-cheng, XING Jiao-ping, CHEN Fu-sheng
    2021, 40(7):  2076-2084.  doi:DOI: 10.13292/j.1000-4890.202107.021
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    Nutrients supply and carbon input affect the stability of soil organic carbon in forests. In this study, we examined the effects of nitrogen deposition, coupling exogenous nutrients and carbon sources on soil organic carbon mineralization and mineral nitrogen release in a Chinese fir (Cunninghamia lanceolata) plantation in hilly mountainous area at the later stage of the treatments. Soils were treated with following conditions: no addition (CK); N addition alone \[N\]; N and carbon additions \[N+C\]; N and non-N nutrient additions \[N+nutrient\]; N, non-N nutrients and carbon additions \[N+both\]. The results showed that the total mineralization of soil organic carbon under different treatments increased with time extension during 720 days incubation, while the mineralization rate gradually decreased. After 360 days incubation, the contents of soil NH4+-N, NO3--N, and mineral nitrogen under all the treatments were higher than those under CK. After 720 days incubation, the contents of NO3--N and mineral nitrogen were the highest under the \[N\] treatment, followed by the treatments \[N+nutrient\], \[N+both\], and \[N+C\]. The activity of β-glucosidase was the highest under the \[N+both\] treatment, followed by \[N+C\], CK, and \[N\]. The activity of β-N-acetyl-glucosaminidase was the highest under the \[N+both\] treatment. The activity of acid phosphatase was higher under the treatment of \[N+both\] and \[N+C\] than that under the \[N\] treatment and CK. Under the background of nitrogen deposition, long-term input of non-nitrogen nutrient and carbon into soils will promote soil organic carbon decomposition and thus weaken soil carbon sequestration in forests.
    Mechanism of different ameliorated methods to improve primary productivity of sand land: Soil microenvironment.
    WANG Jie, ZHANG Yun-long, JIA Xiao-tong, ZHAO Jin-ling, JING Ming-hui, CAO Juan, BIAN Jian-lin, YU Qiang, CAO Yuan-bo, WU Hong-hui
    2021, 40(7):  2085-2093.  doi:DOI: 10.13292/j.1000-4890.202107.010
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    The restoration of soil microenvironment is the basis for the restoration of sand land and desertified grassland. However, it is not clear how the improvement measures interact with the soil microenvironment to increase primary productivity of sandy land. Here, we conducted an experiment in a semifixed dune in Xilingol, Inner Mongolia, to examine the impacts of different improvement measures on sandy soil microenvironment. We measured soil physical properties (soil bulk density, aggregates, temperature, moisture) and plant biomass under two treatments: threedimensional measure (crust + water retention agent), comprehensive measure (seeding + crust + water retention agent) and control. Our results showed that both the threedimensional and comprehensive measures improved soil structure (lower soil bulk density and higher water stability of large aggregates), increased soil infiltration and soil water content, but reduced water evaporation. Both ameliorations reduced the average daily temperature in summer, which was beneficial to reduce water evaporation. The three-dimensional measure increased the average daily temperature in early spring, which might promote seed germination, thus improving the utilization rate of snow water. Both measures reduced diurnal temperature variations. The lower daytime temperature was conducive to reducing water evaporation. Compared with the three-dimensional measure, the comprehensive measure increased plant biomass due to sowing treatment, which in turn improved soil microenvironment, and thus obtained a better improvement effect. This study provides empirical evidence for the use of three-dimensional and comprehensive measures for improving the microenvironment and primary productivity of sandy soils.
    Effects of spring rainfall distribution on soil respiration in a coastal wetland of the Yellow River Delta.
    MA Shu, TAO Bao-xian, HAN Guang-xuan, WANG Xiao-jie, LI Pei-guang, CHU Xiao-jing
    2021, 40(7):  2094-2103.  doi:DOI: 10.13292/j.1000-4890.202107.007
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    Changes of rainfall seasonal pattern would affect carbon cycling in coastal wetlands by influencing the transport of water and salt in soils. Seed germination and plant growth in coastal wetlands are sensitive to rainfall availability in spring, but the underlying mechanism of spring rainfall distribution on soil respiration is still unclear. An insitu spring rainfall control field experiment with five treatments (+73%, +56%, control, -56% and -73% in spring, but the annual total rainfall remained the same) were set up to explore the effects of spring rainfall distribution on soil respiration of a coastal wetland on the Yellow River Delta. Soil water content in spring significantly increased with the increasing rainfall partitioning in spring, while that in autumn significantly decreased. The seasonal variation of soil salinity was opposite to soil moisture, and soil salinity showed strongest fluctuations in spring compared with other seasons. The total belowground biomass and the proportion of belowground biomass in deep soil layer increased with the increasing spring rainfall partitioning, while the proportion of belowground biomass in shallow soil layer showed an opposite pattern. Mean annual soil respiration rate was decreased with the decreasing spring rainfall partitioning, and was significantly different between +73% and -73% treatments (P<0.05). Soil respiration rate differed among different seasons. Soil respiration rate in spring and summer increased with the increasing rainfall partitioning in spring, but decreased in autumn and winter. However, the positive effect of increased spring rainfall partitioning on soil respiration in spring and summer was much greater than the negative effect in autumn and winter. Mean annual soil respiration was closely related to soil moisture and soil salinity in spring, and remarkably affected by the proportion of belowground biomass of different soil layers and total belowground biomass.
    Litter and its hydrological characteristics of typical forest types in Xishuangbanna.
    LU En-fu, ZHU Xi-ai, ZENG Huan-huan, LIU Wen-jie
    2021, 40(7):  2104-2112.  doi:DOI: 10.13292/j.1000-4890.202107.017
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    Litter layer plays a vital role in the hydrological function of forest ecosystems. We conducted a litter soaking experiment in the laboratory to examine litter hydrological characteristics. Litter was collected from four typical forests in Xishuangbanna, including tropical seasonal rainforest, rubber (Hevea brasiliensis) monoculture, and two rubber agroforestry systems (rubberFlemingia macrophylla and rubberTheobroma cacao). The aim of this study was to provide scientific reference for water resources management under different land use types in tropical area. Our results showed that the total standing litter in the tropical seasonal rainforest was significantly higher than that in other forests (P<0.05), with no difference between rubber monoculture and rubber agroforestry systems (P>0.05). Leaf litter was the largest litter component (accounting for more than 60% of the total) in all forest types. Except for tropical seasonal rainforest, the maximum and minimum water storage rates of litter components in different forest types were leaf > mixed litter > branch+bark > reproductive part. The maximum and minimum water storage rates of each component in tropical seasonal rainforest were significantly higher than that of rubber monoculture (P<0.05). The time-dependent changes in water-holding capacity of litter components were consistent across all the forest types. The waterholding capacity increased rapidly at the beginning stage, then increased slowly, and reached saturation after soaking for about 20 h. At each measurement incidence, waterholding capacity of litters from tropical seasonal rainforest and rubber F. macrophylla agroforestry system was higher than that from rubber T. cacaoagroforestry system and rubber monoculture. The rubber monoculture had the lowest water interception through litter (4.69 t·hm-2), of which 1.7 times in the tropical rainforest and 2.1 times in rubberF. macrophylla agroforestry system. These results indicated that the transformation of a tropical seasonal rainforest to rubber monoculture reduced litter hydrological function. The construction of an agroforestry system with a better litter water interception and holding capacity such as rubberF. macrophylla and rubber T. cacao would have ecological and environmental benefits.
    Distribution of typical antibiotic resistance genes and mobile genetic elements in vegetable soils of Shenyang.
    WANG Bai-yu, ZHANG Xun, WANG Bao-yu, LIN Xin, WU Yi, AN Jing
    2021, 40(7):  2113-2119.  doi:DOI: 10.13292/j.1000-4890.202107.009
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    To understand the distribution of typical antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in vegetable soils of Shenyang in Northeast China, the diversity and abundance of ARGs \[including tetracyclines (tet), sulfonamides (sul), chloramphenicols (cml), and aminoglycosides (aac)\] and MGEs \[including transposons (tnp) and integrons (int)\] were detected in vegetable soils from Shilihe, Dongling, and Xinmintun in Shenyang using highthroughput fluorescence quantitative PCR. The results showed that 21 ARGs and 6 MGEs were detected in the soil samples. The detection rate of cml was the highest (100%), while the varieties of tetwere the largest (14 species). Five ARGs (including tetG-01,tetG-02, tetL-02,tetX,cmx(A)) and 3 MGEs (including tnpA-04, tnpA-05 and intI-1(clinic)) were detected. The diversity and abundance of ARGs were highest in the greenhouse soil samples from Xinmintun, followed by the greenhouse soil samples from Dongling and the general vegetable soil samples from Shilihe. The enrichment of ARGs in rhizosphere soil was significantly higher than that in non-rhizosphere soil. There was a significant positive correlation between the ARGs (sul and cml) and MGEs, indicating that MGEs might promote the migration and diffusion of the ARGs in soils. Our results provide scientific support for evaluating the ARGs pollution in soils and preventing the ecological risk of ARGs in Shenyang vegetable soils.
    Effects of urban sludge farming on crop yield and soil quality in irrigated desert soil.
    YAO Jia-xuan, E Sheng-zhe, YUAN Jin-hua, CHE Zong-xian, WANG Yu-xuan, ZHAO Tian-xin
    2021, 40(7):  2120-2132.  doi:DOI: 10.13292/j.1000-4890.202107.026
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    Agricultural use of urban sludge is a main way for processing municipal sludge. However, such applications have the risks of heavy metal pollution. This study is aimed to explore the reasonable application of sludge by a field experiment in Hexi oasis irrigated desert soil. The experiment included five treatments: conventional fertilization (NP) as control, conventional fertilization + urban sludge compost 9000 kg·hm-2 (NPS9000), conventional fertilization + municipal sludge compost 18000 kg·hm-2 (NPS18000), conventional fertilization + municipal sludge compost 18000 kg·hm-2 + green manure returning planted after wheat harvest (NPGrS18000), and conventional fertilization + municipal sludge compost 18000 kg·hm-2 + replanting green manure and removal (NPGtS18000). We examined the effects of sludge and green manure application on soil physical and chemical properties, organic carbon and total nitrogen sequestration rate, nitrogen, phosphorus and potassium activation coefficient, crop yield, and heavy metal contents in a wheatcorn cropping system. The results showed that the effects of four treatments of sludge application on corn yield were equivalent to that of NP, while wheat yield was significantly increased. The difference of wheat yield in the four treatments with sludge application gradually changed from significant to insignificant with increasing duration of sludge application from 2015 to 2019. Sludge application increased the contents of soil organic matter, total nitrogen, total phosphorus, alkali hydrolyzable nitrogen and available phosphorus, activated soil nitrogen, phosphorus and potassium, increased organic carbon and total nitrogen sequestration rate, and reduced soil pH and bulk density. The application effect was positively correlated with application rate. Although sludge application or sludge + green manure returning slightly increased the accumulation of heavy metals in the soil, the contents of all heavy metals were lower than the national safety standards of China. The zinc and lead contents of corn grains in NPS18000 treatment and the zinc content of corn grains in NPGtS18000 treatment were significantly higher than those of NP treatment. The input amount of heavy metals by the sludge application was much greater than the output amount by harvesting crops. In summary, the application of sludge could significantlyincrease soil fertility and wheat yield. High-level sludge application combined with removal of green manure could inhibit the absorption of zinc and lead by corn grains and increase the output of heavy metals from the cropping system. To ensure that the zinc and lead contents in corn grains are below safe limits, annual input amount of zinc and lead carried by the sludge application should be lower than 348 g·hm-2 and 9.5 g·hm-2.
    The community structure of parrotfish in typical islands and reefs of the South China Sea.
    QUAN Qiu-mei, WANG Teng, LIU Yong, GUO Jia-tong, XIE Yu-fang, LI Chun-ran, LI Chun-hou
    2021, 40(7):  2133-2145.  doi:DOI: 10.13292/j.1000-4890.202107.029
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    Clarifying the effects of human activities on parrotfish can provide scientific basis for the protection and reasonable development of parrotfish resources. We carried out a survey on parrotfish in typical islands and reefs in the South China Sea in July 2020. The results showed that a total of 20 parrotfish species belonging to four genera were recorded. Among those species, 14 species were found in the Meiji reef and Jinqing island, and 9 species were found in Lingshui, Hainan Province. Biodiversity indices (Shannon diversity index (H), Pielou evenness index (J), and Margalef diversity index (D)) were in order of Meiji reef (3.09, 0.81, 2.50) > Jinqing island (2.32, 0.61, 2.27) > Lingshui (1.66, 0.52, 1.44). Human population density increased and biodiversity decreased from offshore islands to nearshore zone, suggesting that fishing intensity was increased from Meiji reef to Jinqing island to Lingshui. In addition, the number and weight percentage of excavators that were susceptible to human disturbance were in order of Meiji reef (28.96%, 26.27%) > Jinqing island (15.86%, 10.60%) > Lingshui (1.15%, 0.51%). The number and weight percentage of browsers that were similarly sensitive to overfishing were also in order of Meiji reef (1.64%, 0.82%) > Jinqing island (1.29%, 0.76%) > Lingshui (0, 0). The spatial variation of the structure composition of feeding functional groups also reflected the difference of fishing pressure in different regions. The standardized body length of parrotfish in each feeding functional group (i.e. the ratio of body length to the maximum length of corresponding species in Fishbase database) showed the order of Jinqing island > Meiji reef > Lingshui (P<0.05), which is consistent with the intermediate disturbance hypothesis. Moderate fishing can reduce interspecific competition for parrotfish in Jinqing island, leaving more space and food resources for surviving parrotfish, while long-term overfishing tends to reduce the individual size of parrotfish.
    Population growth and reproduction characteristics of Parabramis pekinensis in the lower reaches of the Yangtze River.
    LIU Si-lei, WANG Yin-ping, LI Pei-jie, CAO Guo, WANG Lei, DAI Pei, HU Min-qi, LIU Kai
    2021, 40(7):  2146-2154.  doi:DOI: 10.13292/j.1000-4890.202107.025
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    To understand the growth and reproduction characteristics of Parabramis pekinensis in the lower reaches of the Yangtze River, we collected 1040 samples from Tongling, Wuhu, Dangtu, Zhenjiang, Jingjiang, and Nantong sections for four consecutive quarters from 2017 to 2018. Body length of the fishes ranged from 84.79 to 305.00 mm. Body weight ranged from 8.50 to 673.39 g. The ratio of male to female was 1∶0.97. The ages ranged from 1 to 6 years. Individuals with 2 and 3 years old dominated the population, with a contribution of 87.9%. Von Bertalanffy growth equations were as follows: Lt=331.09×[1-e-0.22(t+0.27)],Wt=589.05×[1-e-0.22(t+0.27))]2.964. The inflection point age of growth was ti=4.67 a, the corresponding body weight was 174.00 g, and the corresponding body length was 219.42 mm. By dissecting 24 samples, we recorded that the absolute fecundity ranged from 1630 to 154247 grains, with an average of 35792±39381 grains. The relative fecundity per unit weight was 10.99-383.70 grains·g-1, with an average of 120.06±89.68 grains·g-1. The relative fecundity per unit length was 7.89-598.44 grains·mm-1, with an average of 142.23±135.78 grains·mm-1. The absolute fecundity had a linear and exponential relationship with body length and weight, respectively. Our results indicate simple age structure of Parabramis pekinensis in the lower reaches of the Yangtze River, with young individuals predominantly and weak reproductive potential, but a higher level of the growth parameters. Corresponding protective measures should be taken for the sustainable use of Parabramis pekinensis resources.
     Light environment optimization of culvert fishway based on the phototaxis of Schizothorax prenanti.
    HUANG Jie, LIN Chen-yu, SHI Xiao-tao, ZHANG Ning, SHI Shang-shang, CHENG Bi-xin, MO Wei-jun
    2021, 40(7):  2155-2163.  doi:DOI: 10.13292/j.1000-4890.202107.035
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    Culverts are important in maintaining surface water flow and guaranteeing the integrity of the local water habitat, and thus providing gene exchange channel for the majority of migratory fish. As an important factor affecting the efficacy of culvert fishways, the darkened environment in the culvert barrel partly delays the ascending migrants, impairing the passage performance for target fish. We set up typical light conditions in a physical culvert model and conducted an experiment with Schizothorax prenanti, a coldwater species with economic significance in China. We examined the behavioral strategies and upstream swimming of S. prenanti in the culvert passage under different light treatments, including two colors (white light and green light), three illuminance levels (10-100 lx, 100-1000 lx, and above 1000 lx), and the control group of total darkness, by measuring the attempts, attempt success rate, and the distribution within and outside the culvert. The attempts of fish in the green light treatment of 100-1000 lx were significantly higher than that in the green light of 10-100 lx (P=0.009) and white light of the same illuminance (P=0.044). The change of illuminance and color settings did not affect attempt success rate of S. prenanti (P=0.819). The white light motivated the attempts of test individuals into the culvert at the illuminance range of 0-1000 lx, contributing to the successful pass with a certain probability, while it sparked the escapes at above 1000 lx. The green light of 100-1000 lx substantially increased the proportion of S. prenanti reaching the upstream of the culvert (22.50±8.74)% while trapped the fish in the barrel at above 1000 lx, reduced the ratio to (16.44±4.01)%. Our study provided an optimizing strategy for culvert fishway, i.e. alluring the target fish into the entrance with the green light of 100-1000 lx and then accelerating the passage using white light of 1000 lx.
    The bioturbation from larvae of Chironomussp. andLimnodrilus hoffmeisteri alleviated the physiological stress of native species Bellamya purificata  after invasion of Pomacea canali culata.
    LIU Ming-yuan, ZHANG Ye-jun, HENG Yang, CHEN Nai-fei, XU Wei-yin, ZOU Wei
    2021, 40(7):  2164-2174.  doi:DOI: 10.13292/j.1000-4890.202107.036
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     Pomacea canaliculata is one of the first 16 vicious invasive species in China. It causes serious adverse effects on the survival and continuation of native species through direct (feeding and competition) and indirect ways (ecological disturbance). In order to explore whether the native bioturbator, such as Limnodrilus hoffmeisteri and larvae of chironomus sp., can alleviate the ecological extrusion of Pomacea canaliculata on the native near niche species,Bellamya purificata, we carried out three experiments. The 15day survival rate, relative change rate of body weight and relative change rate of individual body weight of the two snails were observed after the addition of Limnodrilus hoffmeisteriorlarvae of chironomus sp. in the separated and co-cultured system ofPomacea canaliculataand Bellamya purificata. We examined the effects caused by different density and distribution of Limnodrilus hoffmeisteri and larvae ofchironomus sp. on the stress of Bellamya purificata after the invasion of Pomacea canaliculata. The results showed that the survival rate of Pomacea canaliculatawas significantly higher than that of Bellamya purificata in the absence of bioturbator, whereas the survival rate of Pomacea canaliculata was significantly reduced (P<0.05) and that of Bellamya purificata was significantly increased (P<0.05) after adding bioturbators, with higher body weight loss of Bellamya purificata(P<0.05). Regardless of the density of Limnodrilus hoffmeisteri, the survival rate ofPomacea canaliculatawas significantly reduced (P<0.05), and that of Bellamya purificata was significantly increased (P<0.05) after adding Limnodrilus hoffmeisteri. Such effect was the greatest at high density, which significantly reduced the survival rate of Pomacea canaliculata(P<0.01). From the distribution of bioturbator in the water, it was the most favorable for the survival of Bellamya purificatawhen Limnodrilus hoffmeisteri was evenly distributed. Although the addition of both Limnodrilus hoffmeisteri and larvae of chironomus sp. was beneficial to the survival of Bellamya purificata and weakened the invasive influence of Pomacea canaliculata, the effect of Limnodrilus hoffmeisteri was better than that of larvae of chironomus sp.

    Community structure of macrozoobenthos and its relationship with environmental factors in Baiyangdian Lake.
    CHEN Ze-hao, YANG Wen, WANG Ying, FU Jun, PEI Yuan-sheng
    2021, 40(7):  2175-2185.  doi:DOI: 10.13292/j.1000-4890.202107.001
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    The characteristics of macrozoobenthos and environmental factors in water and sediment in Baiyangdian Lake were investigated in 2018. The relationship between community structure of macrozoobenthos and environmental factors were analyzed. Results showed that macrozoobenthos consisted of 6 classes and 21 species in Baiyangdian Lake, with Gastropoda and Insecta being the dominant classes. The mean biomass and abundance had temporal and spatial variations. The mean biomass of macrozoobenthos peaked in summer, while the mean abundance of macrozoobenthos peaked in spring. The maximum of mean biomass was found in Nanliuzhuang site, while the maximum of mean abundance was found in Dongtianzhuang site. Quantified by the diversity index, water quality of Baiyangdian Lake was at a low level. Nitrogen and phosphorus contents in water and carbon and nitrogen in sediment were relatively high. NO3--N, TN, temperature and TOC in water and NO3--N, pH and NH4+-N in sediment were the main environmental factors influencing macrozoobenthos. Our results could provide a basis for restoration and management of macrozoobenthos in Baiyangdian Lake.
    Macrobenthic community and species diversity by trawing in two national aquatic germplasm reserves of the Southern Yellow Sea.
    YUAN Jian-mei, ZHANG Hu, HU Hai-sheng, BEN Cheng-kai, XIAO Yue-yue, ZU Kai-wei, ZU Chao-wen
    2021, 40(7):  2186-2193.  doi:DOI: 10.13292/j.1000-4890.202107.033
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    The community structure and species diversity of macrobenthos in two national aquatic germplasm reserves of South Yellow Sea were studied based on the trawling macrobenthos of three seasons from August 2019 to April 2020. A total of 78 macrofauna species were identified, including 30 species of crustaceans, 25 species of fishes, 12 species of mollusks, 10 species of echinoderms and 1 species of polychaete. There was no seasonal variation in dominant species in the Reserve of Chinese Shrimp. Crustaceans were the dominant species in the Reserve of Silver Pomfret. Species diversity index differed between the two reserves only in summer (P<0.05). Ourresults provide basic data for the biodiversity research of reserves and technical support for the protection and sustainable utilization of fishery resources.
    Effects of temperature on Erannis ankeraria at different developmental stages.
    ZHOU Zhuo, DUAN Jing-Pan, HAN Li, WANG Qing-Hua, ZHANG Yong-An, DUAN Li-Qing
    2021, 40(7):  2194-2200.  doi:DOI: 10.13292/j.1000-4890.202107.016
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    Erannis ankeraria is one of the most important pests in larch. In order to investigate the effects of temperature on E. ankeraria, larch (Larix principisrupprechtii) branches were inserted into water in the bottles to keep fresh and used as the host plant to rear the larvae. Seven constant temperatures (15, 19, 23, 25, 27, 29 and 31 ℃) were set up to test the effects of temperature on the developmental duration and survival of eggs, larvae and pupae of E. ankeraria. The results showed that temperature significantly affected developmental duration, survival rate, pupa weight, fecundity, and oviposition rhythm of E. ankeraria. E. ankerariacould complete the individual development cycle from egg to adult only within the range of 15-19 ℃.Adults could not emerge when the temperature was above 23 ℃. The pupation rate decreased as the temperature was above 25 ℃. The hatching rate and larval survival rate decreased at 29 ℃. The developmental threshold temperature of over-wintering eggs and larvae of E. ankerariawas 9.7 and 4.3 ℃, respectively. The effective accumulated temperature was 104.2 and 459.8 day-degree, respectively. E. ankeraria preferred to grow and develop at low temperature. High temperature inhibited its growth and development. Higher temperature reduced the pupation rate and emergence rate. Pupal stage was the most sensitive stage to increasing temperature. Increased temperature led to earlier emergence of male moth than female moth, which reduced the chance of male and female moth encountering, thus affecting the reproduction. It is inferred that E. ankerariawill move northward in order to survive under global warming scenario, and that their damage to larch in warm areas will be reduced.
    Effects of landscape pattern change on bird diversity in Anhui Anqing Caizi Lake National Wetland Park.
    LIU Da-zhao, ZHOU Li-zhi
    2021, 40(7):  2201-2212.  doi:DOI: 10.13292/j.1000-4890.202107.004
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    Wetland landscape patterns of shallow riverconnected lakes exhibit distinct seasonal dynamics under natural hydrological regime. To elucidate the impacts of landscape pattern changes on bird diversity, we investigated the distribution of bird species and abundance in Anhui Anqing Caizi Lake National Wetland Park during the high (August-October 2019) and low (November 2019-January 2020) water seasons. The characteristics of landscape elements were analyzed using the landscape pattern index method based on remote sensing image data, and the relationship between bird diversity and landscape elements was studied. The results showed that there were 11 orders, 31 families, and 61 species of birds in the park. Among all the recorded species, three species were under the national Class Ⅰ key protection, six species were under the national Class Ⅱ key protection, and 15 species were under the key protection of Anhui Province. During the highwater season, birds were mainly distributed in the rational utilization zone and were predominantly forest birds. During the lowwater season, birds were concentrated in an ecological conservation zone and were primarily Anseriformes, with a maximum number of 10974 individuals. Species richness and bird diversity index were higher in the highwater season than in the low-water season, whereas the abundance of water birds was higher in the low-water season than in the highwater season. Bird diversity index was significantly higher in rational utilization zone than that in other functional zones, with a decreased diversity index monthly. The results of canonical correspondence analysis showed that landscape diversity index, uniformity index, fragmentation, mudflat area, and grassland area were the main factors influencing bird diversity in the wetland park.
    Effect of reclamation on the characteristics of surface arthropod community in coal gangue.
    XIN Wei-dong, LIU Hua-yu, YANG Yi-meng, ZHAO Hao-zhi
    2021, 40(7):  2213-2222.  doi:DOI: 10.13292/j.1000-4890.202107.003
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    We examined the differences in the impacts of reclamation modes on the arthropod community characteristics on the surface of coal gangue dumps, peach tree field,Zanthoxylum bungeanum field and waste grassland in coal gangue dumps in Huozhou, with the nearby corn field not affected by coal gangue dump as the control. The surface arthropod community was investigated by trapping method. The arthropod community structure, diversity and their relationships with environmental factors were quantified by species diversity index, similarity index and CCA ordination method. The results showed that a total of 3585 individuals from 46 arthropod groups were captured. The dominant groups were Neanuridae and Sminthuridae in peach tree field, Entomobryidae and Formicidae in Z. bungeanum field, Formicidae and Carabidae in corn field, and Acrididae, Aphidoidea and Formicidae in waste grassland. There were four common groups in peach tree field and eight groups in Z. bungeanum field. The common groups of both waste grassland and corn field were 13 types. The total number of waste grassland individuals was the least among the four plot types. Reclamation significantly affected the activity density, evenness, dominance and abundance of surface arthropod groups, but did not affect species diversity. Activity density, evenness, and dominance were all manifested as a significant difference between waste grassland and other plots, while the abundance was manifested as a significant difference between corn field and other plots. Results of CCA analysis showed that soil available potassium and organic matter contents were the major environmental factors affecting the characteristics of surface arthropod communities. Reclaiming peach tree field is more conducive to the survival of more surface arthropod individuals, while reclaiming Z. bungeanum field can significantly increase the number of surface arthropod groups. Our results provide theoretical guidance for coal gangue reclamation and green mine construction.
    Structural and functional characteristics of microbial communities in aquaculture ponds of Chinese mitten crab Eriocheir sisensis L.
    XU Zheng-chao, DENG Yan-fei, ZHOU Jun, LI Xu-guang, LU Quan-ping, CHEN Feng-wei, ZHOU Gang
    2021, 40(7):  2223-2233.  doi:DOI: 10.13292/j.1000-4890.202107.031
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    We analyzed the structure and function of microbial community and their relationships with environmental factors in aquaculture ponds of mitten crab and water of exogenous river, based on Illumina HiSeq highthroughput sequencing technique. A total of 541349 effective tags were obtained in six water samples of ponds, which were clustered into 2938 OTUs (operational taxonomic units). A total of 551891 effective tags were obtained in six water samples of exogenous river, which were clustered into 2779 OTUs. A total of 557736 effective tags were obtained in six sediment samples of ponds, which were clustered into 8920 OTU. The α-diversity (Sobs index, Shannon index, Simpson index, and Chao index) of the sediment samples was significantly higher than that of the water samples. The results of β-diversity analysis showed that the samples could be divided into two groups according to the microbial community structure, i.e., sediment group and water group. Proteobacteria, Actinobacteria, Cyanobacteria, Verrucomicrobia, Planctomycetes, and Bacteroidetes were the dominant phyla in waters of aquaculture ponds and exogenous river. Proteobacteria, Planctomycetes, Acidobacteria, Verrucomicrobia, Chloroflexi, and Bacteroidetes were the dominant phyla in the sediments. The results of redundancy analysis showed that temperature (r2=0.915, P<0.01), pH (r2=0.8,P<0.01), dissolved oxygen (r2=0.65, P<0.01), and total hardness of water (r2=0.756, P<0.01) were significantly correlated with bacterial community structure, while NH3-N, NO2--N, COD, NO3--N, TP, and TN were not significantly correlated with bacterial community structure. The results of variance partitioning analysis showed that pH, temperature, and dissolved oxygen were highly contributed to the microbial community distribution at phylum level, with a contribution rate of 44.14%, 41.20%, and 33.2%, respectively. A total of 37 predicted functions were obtained at level 2 by TaxFun method. Carbohydrate metabolism and amino acid metabolism were the dominant functions in both water and sediment. The abundance of functional genes involved in amino acid metabolism, lipid metabolism, membrane transport, xenobiotic biodegradation and metabolism in the sediments was significantly lower than that in the water, while the abundance of functional genes involved in energy metabolism, glycan biosynthesis and metabolism in the sediments were significantly higher than that in the water. Our results provide a scientific basis for the environmental regulation and ecosystem maintenance of mitten crab culture.
    Research progress on the tradeoff between seed regeneration and sprout regeneration and the factors influencing the early process of forest regeneration.
    LI Rong, ZHANG Ting, XIE jin, WANG Jing, YAN Qiao-ling
    2021, 40(7):  2234-2242.  doi:DOI: 10.13292/j.1000-4890.202107.022
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    Natural regeneration is a significant ecological process in forest ecosystems and the foundational approach of forest restoration. As two basic modes of natural recruitment of woody species, seed regeneration and sprout regeneration have advantages and disadvantages and complement each other. The early process of forest natural regeneration is the bottleneck of sapling establishment. Thus, it is necessary to compare the early processes of seed and sprout renewal for understanding forest natural regeneration, predicting population/community development, and identifying pathways for forest restoration. Here, we reviewed the ecological significance and influencing factors of tradeoff between two natural regeneration modes of woody species, compared the differences in the characteristics of seed and sprout-origin seedlings, and summarized the effects of biological factors, abiotic factors and interference on the early process of these two regeneration pathways. The main problems in the current research are proposed. In the future, more attention should be paid to the study of early sprout regeneration process, comprehensive research of forest regeneration impact factors and the interference mechanism should be carried out, and the guiding role of forest natural regeneration theory in forest management practice should be highly appreciated, aiming to provide scientific support for promoting natural regeneration and sustainable development of forests.
    Research advance and future prospect on production of biodiesel from waste cooking oil.
    LIU Yu-xia, XU Jia-ba, ZHANG Qiang-bin, CHEN Chun-mao, ZHOU Qing-xiang, ZHOU Qi-xing
    2021, 40(7):  2243-2250.  doi:DOI: 10.13292/j.1000-4890.202107.005
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    Biodiesel produced from waste cooking oil is an alternative clean fuel to fossil diesel. The development and widespread application of biodiesel will reduce the consumption of fossil diesel, which provides an effective way to recycle and reuse waste cooking oil. In this review, we introduced the production and disposal processes of kitchen waste and waste cooling oil in China, as well as the global status and development of biodiesel produced from waste cooking oil. The dominant transesterification methods and technologies were summarized, while the major issues and challenges for efficient production of biodiesel from waste cooking oil in China were discussed. Finally, we prospected future research of the biodiesel produced from waste cooking oil, and provided some suggestions on its rapid and sustainable development.
    Assessment of forest ecosystem integrity dynamics in Changbai Mountain National Nature Reserve.
    ZHANG Peng-yi, MA Tian-xiao, LIU Bo, LIANG Yu, HUANG Chao, WU Miao-miao, JIANG Si-hui
    2021, 40(7):  2251-2262.  doi:DOI: 10.13292/j.1000-4890.202107.013
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    The assessment of forest ecosystem integrity dynamics can reflect changes in structure and function of forest ecosystems, which is of great significance for establishing longterm effective ecosystem management measures. Here, we developed an indicator system to assess forest ecosystem integrity of the Changbai Mountain National Nature Reserve with surrounding 8km radii in 2005, 2030, 2070, and 2100 by combining the ecosystem integrity assessment framework (EIAF) and a forest landscape model (LANDIS PRO). The results showed that forest ecosystem integrity of Changbai Mountain had a slight decline in 2005-2030 and a continuous increase in 2030-2100. The transfer area among various levels of forest ecosystem integrity continuously reduced over time, while the pattern of forest ecosystem integrity with different levels tended to be stable. Spatially, the overall integrity of the Changbai Mountain forest ecosystems was relatively high. However, there were some patches with low ecosystem integrity in this region due to historical typhoon and anthropogenic disturbance. The ecosystem integrity was higher within than outside the nature reserve. The forest ecosystem integrity of the north and west sides was higher than that of the east side of Changbai Mountain. In the future, it is necessary to strengthen management in areas with low forest ecosystem integrity to facilitate forest recovery.
    Effects of urban park green space on air PM10 and PM2.5 and its effect field characteristics: A case of  Wuhan Zhongshan Park.
    CHEN Yu-yang, WANG Jing, ZHAO Ling-yan, ZHU Chun-yang
    2021, 40(7):  2263-2276.  doi:DOI: 10.13292/j.1000-4890.202107.032
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    We analyzed the effect field of green space in Wuhan Zhongshan Park on the air PM10 and PM2.5 concentrations of surrounding built-up environment in four seasons using the LUR model, small-scale measurement, and spatial interpolation technology, aiming to provide scientific basis for the planning and construction of the built-up environment in the surrounding of green space. The results showed that the LUR model for air PM10 and PM2.5 concentrations was successfully developed according to the key variables including geographic variables (the length of traffic road, area of water bodies, area of nonhard underlying surface, distance from the city center, and distance from the edge of green space) and meteorological variables (air temperature, relative humidity, and wind speed), with an adjusted R2 of 0.203-0.873 for PM10 and 0.306-0.837 for PM2.5 and a leave-one-out crossvalidation R2 of 0.302-0.999 for PM10 and 0.344-0.991 for PM2.5. In addition, the spatial distribution of air PM10 and PM2.5 concentrations was significantly correlated with traffic road length, air temperature, and distance from the city center in the seasonal LUR models (P<0.05). A significant effect of green space on air PM10 and PM2.5 attenuation was detected with an effect field of 250m in winter and 400m in spring, with the maximum of daily reduction of 47.2 μg·m-3 for air PM10 and 15.5 μg·m-3 for air PM2.5. The highest air PM10 and PM2.5 concentration occurred at 8:00-9:00 in spring, summer, and autumn, and at 15:00-16:00 in winter.