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Table of Content

    18 May 2017, Volume 28 Issue 5
    Contents
    Factors influencing tree radial growth of three common species in broad-leaved Korean pine mixed forests in Changbai Mountains, China
    CAI Li-rong, KUANG Xu, FANG Shuai, YUAN Zuo-qiang, LIN Fei, YE Ji, HAO Zhan-qing, WANG Xu-gao
    2017, 28(5):  1407-1413.  doi:10.13287/j.1001-9332.201705.031
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    To understand the factors influencing tree radial growth, we analyzed the seasonal dynamics of tree growth of 3 common species (Pinus koraiensis, Tilia amurensis, Quercus mongolica), compared interspecific growth rates and explored the effects of size, neighborhood competition, soil and topography based on five years dendrometer bands monitoring data of the 3 common species in a broad-leaved Korean pine (P. koraiensis) mixed forest plot in Changbai Mountain, Northeast China. The results showed that the growth dynamics of 3 species were consistent. Trees began to grow in late May, thrived in July, grew at declining rates from late August and stopped growing in late October. Annual relative growth rates were significantly different among the species. Q. mongolica tended to grow faster than the other two species, and the differences of growth rates among the 3 species were especially large for small and medium trees. Tree growth rates of P. koraiensis and Q. mongolica were strongly decreased by neighborhood competition, while tree growth rate of T. amurensis was significantly related to tree size, soil and topography.
    Effects of target tree tending on community structure and diversity in subtropical natural secondary shrubs
    ZHANG Hui, ZHOU Guo-mo, BAI Shang-bin, WANG Yi-xiang, YOU Yu-jie, ZHU Ting-ting, ZHANG Hua-feng
    2017, 28(5):  1414-1420.  doi:10.13287/j.1001-9332.201705.037
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    The typical natural secondary shrub community was chosen in Lin’an of Zhejiang Pro-vince to discover its possibility of restoration to arbor forest with three kinds of forest management models being taken, i.e., no care as control, closed forest management and target tree tending. Over four years growth, compared with control, closed forest management significantly increased average DBH and height by 130% and 50%, respectively, while 260% and 110% for target tree tending. In target tree tending plots, larger trees had been emerging with 4.5-8.5 cm diameter class and 4.5-8.5 m height class and formed a new storey of 4 m compared with control. The species biodiversity indexes at shrub layer were significantly increased in closed management plots, and did not decrease in target tree tending plots. Closed forest management did not change the tree species composition, following its previous succession direction. However, target tree tending increased the importance value of target species with the high potential succession direction of mixed coniferous-broadleaved forest. The results revealed that the secondary shrub community with target tree tending achieved more desired goals on DBH and height growth of dominant trees and species composition improvement compared with closed management. If the secondary shrub community could be managed when the operational conditions existed, target tree tending model should be selected to accelerate the restoration of shrub toward arbor forest.
    Species composition, structure and spatial distribution of secondary cold-temperate Picea forest in Guandi Mountain, China
    YANG Xiu-qing, SHI Chan, WANG Xu-gang, MA Hui-jing, YAN Hai-bing
    2017, 28(5):  1421-1430.  doi:10.13287/j.1001-9332.201705.023
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    The secondary Picea forest is one of the dominant vegetation types in Guandi Mountain. It’s also the representative type of evergreen cold-temperate coniferous forests in subalpine region of north China. A 4 hm2 fixed monitoring Picea forest plot was established in Pangquangou Nature Reserve, Guandi Mountain (GDS plot) to better understand the basic characteristics such as species composition, community structure and its potential ecological process and mechanisms. We analyzed species composition, structure and spatial distribution of sample forest based on the first background survey data in this paper. The results showed that a total of 30 woody plant species existed in the sample area, which belonged to 11 families, 22 genera. The total individual number (including branches) was 26218 (independent individual number was 10266). Floristic composition in the region was defined as north temperate elements. Big differences of individual number, average diameter at breast height (DBH) and basal area among different species caused significant community layering effect, and the dominant species in each layer was obvious. Size-class structure of species showed bimodal skewed normal distribution at the canopy layer, approximate normal distribution at the subtree layer, and ‘L’ type distribution at the shrub layer. Spatial distribution of the dominant tree species such as Picea wilsonii and Larix principis-rupprechtii showed different pattern features with the changing size class, whether in individual number or in aggregation degree. Compared with the above two species with the same size class, a large number of L. principis-rupprechtii with DBH≥30 cm aggregated in the center of sample plot, but few P. wilsonii individuals with DBH≥30 cm occurred in the plot and had no clustering distribution. Only a few L. principis-rupprechtii with DBH≤10 cm occurred in the plot with a scattering distribution, and a large number of P. wilsonii with DBH≤10 cm aggregated in the center of the plot. There were also many P. wilsonii individuals with DBH≤10 cm distributed in the northwest area of the plot, but Betula albo-sinensis individuals with DBH≤10 cm mostly distributed in the southeast area of the plot. Shrub species such as Cotoneaster acutifolius, Spiraea pubescens and Lonicera szechuanica also showed heterogeneous spatial distribution. Species distribution pattern was affected by habitat conditions, and related to its own development, regeneration traits and ecological habits.
    Effects of mulching management of Phyllostachys heterocycla forests on the characteristics of soil infiltration and biometrics in southwest Zhejiang Province, China
    WANG Yi-kun, JIN Ai-wu, FANG Sheng-zuo
    2017, 28(5):  1431-1440.  doi:10.13287/j.1001-9332.201705.038
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    Soil infiltration, soil physical and chemical properties, root length density and soil fauna diversity were studied in Phyllostachys heterocycla forests with different mulching times in southwest Zhejiang Province, China. Significant differences of soil infiltration capability were found among the forests with different mulching times and among soil layers. Soil infiltration capability generally declined in the deeper soil layers. With mulching management, soil infiltration capability increased under the first mulching, and then declined with the increase of mulching times. The Kostiakov model was suitable for simulating soil infiltration process. With the extending of mulching times (4 to 6 years), soil pH and total/non-capillary porosity decreased, while soil bulk density, soil orga-nic matter and total nitrogen contents increased significantly. Soil initial, steady, and average infiltration rates as well as the cumulative infiltration amount correlated closely with the length density of roots with diameter from 0.5 mm to 5.0 mm, showing a decreasing tendency with the decrease in root length density. Soil fauna density was highest in the forest under the first mulching, and was lowest after third mulching. The decreased numbers of large and meso-arthropods, including Symphyla, Chilopoda, Diplopoda, Hymenoptera and pseudoscorpions, and the micro-arthropods, including Oribatida, Mesostigmata, Onychiuridae, Neanuridae, Cyphoderidae, and Entomobryidae, showed negative effects on soil infiltration. In conclusion, long-term mulching changed soil physical and chemical properties, decreased soil infiltration capability, and suppressed the development of soil fauna, which might cause the decline ofP. heterocycla forests.
    Effects of neighbor competition on growth, fine root morphology and distribution of Schima superba and Cunninghamia lanceolata in different nutrient environments
    YAO Jia-bao, CHU Xiu-li, ZHOU Zhi-chun, TONG Jian-she, WANG Hui, YU Jia-zhong
    2017, 28(5):  1441-1447.  doi:10.13287/j.1001-9332.201705.011
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    Taking Schima superba and Cunninghamia lanceolata as test materials, a pot experiment was conducted to simulate the heterogeneous and homogeneous forest soil nutrient environments, and design three planting modes including single plant, two-strain pure plant and two-strain mixed ones to reason the promotion in mixed S. superba and C. lanceolata plantation and the competitive advantage of S. superba. Results showed that compared with the homogeneous nutrient environment, both S. superba and C. lanceolata had the higher seedling height and dry matter accumulation, when mixed in the heterogeneous nutrient environment, S. superba displayed the obviously competitive advantage, which related to its root plasticity. The fine root of S. superba mixed in each diameter class showed a lot of hyperplasia, and the root total length, surface area and volume of which were 80%-180% higher than that of C. lanceolata. S. superba took the advantage of the compensatory growth strategy of vertical direction in fine roots, namely, they still multiplied to gain greater competitive advantage in low nutrient patches, besides occupying eutrophic surface. The different soil colonization and niche differentiation in fine root of S. superba and C. lanceolata alleviated the strong competition for nutrients of the roots of the two species, and improved the mixed-plantation production. Pure plantation of S. superba harvested the lower yield, which due to the root self-recognition inhibited the growth of root system. Fine roots staggered and evenly distributed on the space might be a reason for stable structure of pure S. superba plantation. So, it was recommended that block surface layer soil preparation and fertilization are used to improve the soil nutrient distribution, and the mixed plantation is constructed to promote the growth of S. superba and C. lanceolata, at the same time, the stand density is regulated to promote tree growth for the pure artificial S. superba plantation which had already been built.
    Clonal water integration contributes to more survival advantages for Populus euphratica young ramets in the hyper-arid habitat
    ZHU Cheng-gang, LI Wei-hong, CHEN Ya-peng, MA Jian-xin
    2017, 28(5):  1448-1454.  doi:10.13287/j.1001-9332.201705.024
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    The proposed investigation was carried on the characteristics of clonal water integration between the Populus euphratica mother tree and its young ramets, as well as its effects on the phy-siological traits of young ramets at the lower reaches of Tarim River. The results showed that there was obvious water integration characterized by acropetal water transport between P. euphratica mother tree and its young ramets. The mean daily flow by water integration from the mother tree to its young ramets was three times as the seedlings with similar growth status at the same habitat by getting water by itself roots. Compared with the P. euphratica seedlings, the young ramets could take much more water from relatively deeper soil layers just like their mother tree. It indicated the young ramets maintained a better water acquisition ability due to clonal water integration. There was obviously higher leaf water content of young ramets than seedlings, and especially the water potential in the predawn and midday was increased by 10.0% and 29.7%, respectively. The advantaged water status of young ramets made the photosystem Ⅱ electron transport rate and actual photochemical efficiency of photosystem Ⅱ in light-adapted leaves increase by 23.4% and 11.5% than seedlings, respectively, and also made the young ramets maintain a significantly lower excess excited energy in photosystem Ⅱ and a lower risk of photoinhibition than seedlings. All of the above cha-racteristics would impel the P. euphratica young ramets had higher survival advantages than seedlings at hyper-arid habitats.
    Physiological responses of five plants in northwest China arid area under drought stress
    DING Long, ZHAO Hui-min, ZENG Wen-jing, LI Qing, WANG Yang, WANG Si-qing
    2017, 28(5):  1455-1463.  doi:10.13287/j.1001-9332.201705.034
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    Effects of drought stress on photosynthetic characteristics, water status, physiological and biochemical indexes were studied in five arid area plants in northwest China, including Potentilla fruticosa, Lycium ruthenicum, Caryopteris mongholica, Caragana korshinskii and Hedysarum scoparium, using pot experiments. The results showed that with the prolongation of drought stress, the water conservation capacity of leaves totally increased in above five plants, the leaf relative water content rose first and then fell, and the relative chlorophyll content and chlorophyll fluorescence parameters decreased to some extent. Overall, the photosynthetic system of H. scoparium and L. ruthenicum least affected by the stress, and P. fruticosa suffered with the most serious damage. The electric conductivity and malondialdehyde (MDA) content of P. fruticosa firstly decreased and then sharply increased, while superoxide dismutase (SOD) and peroxidase (POD) activities firstly increased and then dramatically decreased. With the decrease of soil water content, the electric conductivity rose firstly and then fell in the other four plants,the change of MDA content rose first and then fell, or fell first and then rose, and the activities of SOD and POD almost displayed upward trend. Especially, SOD activity of C. mongholica and POD activity of H. scoparium had the biggest increment among the five plants after 28 days of drought stress, increasing by 1.1 and 13.1 times respectively, compared with before processing. Additionally, there was significant variance in the accumulation of organic solutes among the five plants during the drought stress treatment. The accumulation of soluble sugar and free proline was the most in P. fruticosa, increasing by 1.1 and 22.4 times respectively, after 28 days of drought treatment. H. sco-parium accumulated the most soluble protein, increasing by 1.0 times after 28 days of drought treatment. The result of membership function method showed that the drought tolerance decreased in order of H. scopariumL. ruthenicum C. korshinskii C. mongholica P. fruticosa. The research revealed that all five plants could make positive response to drought stress through improving the activity of antioxidant enzymes and accumulating organic solutes, which could help to reduce cell damage. P. fruticos was most sensitive to water deficit in the five plants, and the degree of drought had exceeded its own regulated capacity threshold during the experiment.
    Analysis and comprehensive evaluation on cold resistance of six varieties of Michelia
    LI Rui-xue, JIN Xiao-ling, HU Xi-jun,CHAI Yi-xia, CAI Meng-ying, LUO Feng, ZHANG Fang-jing
    2017, 28(5):  1464-1472.  doi:10.13287/j.1001-9332.201705.039
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    Taking six varieties of Michelia as test materials, their responses under cold situation in the field were investigated and the semilethal low temperatures were calculated by fitting Logistic equation. The nine structure indexes of leaf tissue were observed by paraffin section, and a comprehensive evaluation on cold resistance of different varieties was given according to subordinate function value analysis. The results showed that the relative electrical conductivity of six varieties of Michelia was significantly positively correlated with the semilethal low temperature (LT50) of 3 h 0-25 ℃ treatment. From high to low, the order of LT50, which ranged between -20.48 ℃and -8.67 ℃, was M. maudiae > M. maudiae var. rubicunda > M. wilsonii > M. ‘liubanhanxiao’ ♀× M. shiluensis ♂ > M. platypetala > M. ‘liubanhanxiao’. The epidermal anticlinal walls of six varieties of Michelia leaves had 1-2 layers and showed slightly sinuated shape. The leaf had 1-3 layers of palisade tissue cells and the differences among the indexes of nine anatomical structures were extremely significant. The thickness of palisade tissue, ratio between palisade tissue and spongy tissue, and thickness of the vein were the key factors affecting cold resistance. The order of cold resistance of six varieties of Michelia, from the strong to the weak, was M. ‘liubanhanxiao’ > M. platypetala > M. ‘liubanhanxiao’ ♀× M. shiluensis ♂>M. wilsonii > M. maudiae var. rubicundaM. maudiae, which was basically consistent with the result of field investigation.
    Photosynthetic characteristics of Emmenopterys henryi seedlings and their relationships with environmental factors
    GUO Lian-jin, DU Jia-peng, WU Yan-ping, XIAO Zhi-peng, LIAO Ting, SHAO Xiu-juan
    2017, 28(5):  1473-1481.  doi:10.13287/j.1001-9332.201705.017
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    To find appropriate environment for Emmenopterys henryi seedlings and develop corresponding strategies for their natural regeneration, the net photosynthetic rate, water use efficiency, chlorophyll content, height, basal diameter and biomass of two-year old seedlings and the relationships with environmental factors were studied in different habitats, i.e., undercanopy, crown edge, forest gap, and forest edge. In the four habitats, the maximum photosynthetically active radiation (PAR) was 50-1380 μmol·m-2·s-1, net photosynthetic rate of E. henryi seedlings showed singlet diurnal variation in undercanopy and crown edge, and showed a bimodal pattern in forest gap and forest edge. Seedlings were shade-tolerant plants with the low shade-tolerant ability. The order of light saturation point, light compensation point, and dark respiration of their functional leaves in different habitats was the same as follows: forest edge > forest gap > crown edge > undercanopy, and the order was inverse when sequenced by apparent quantum efficiency. Seedlings were highly adaptable to forest gap and crown edge, with higher transpiration rate, stomatal conductance, water use efficiency (WUE), and net photosynthetic rate. Seedlings in forest gap had lower leaf chlorophyll content, but they grew fast and therefore showed the maximum biomass. Net photosynthetic rate of the seedlings showed significant positive correlation with PAR and stomatal conductance. For undercanopy, seedling photosynthesis was facilitated by reducing canopy density and increasing light transmittance. For forest edge, vegetation cover should be increased with reducing light intensity to ensure rapid growth of the seedlings.
    Photo-physiological and photo-biochemical characteristics of several herbaceous and woody species based on FvCB model
    TANG Xing-lin, ZHOU Ben-zhi, ZHOU Yan, NI Xia, CAO Yong-hui, GU Lian-hong
    2017, 28(5):  1482-1488.  doi:10.13287/j.1001-9332.201705.029
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    To explore the photosynthetic capacity and the leaf photosynthetic apparatus for plants with different life forms, CO2 response curves of 7 woody species and 4 herbaceous species were fitted by the modified rectangular hyperbolic model and the FvCB model, and the photosynthetic parameters, including maximum net photosynthetic rate (Pn max), maximal Rubisco carboxylation rate (Vc max), maximal electron transport rate (Jmax), day respiration (Rd), and mesophyll resistance to CO2 transport (rm), were compared among different woody species, among different herbaceous species, and between woody and herbaceous life-forms, respectively. The results showed Pn max of seven woody species descended in the order of Sapium sebiferum and Boehmeria nivea > Machilus pingii and Pittosporum tobira > Cyclobalanopsis glauca, Castanopsis sclerophylla, and Quercus nuttallii. Vc max of S. sebiferum, B. nivea, M. pingii, and P. tobira was significantly higher than that of C. glauca and C. sclerophylla. Jmax of woody species was in descending order as S. sebiferum > B. nivea and P. tobira > Q. nuttallii, C. sclerophylla, and C. glauca. rm of M. pingii and C. sclerophylla was higher than that of S. sebiferum, P. tobira and B. nivea. Pn max of Phytolacca acinosa was significantly higher than that of Ageratum conyzoides and Achyranthes aspera. There was no significant difference in Vc max among 4 herbaceous species. Jmax of P. acinosa was higher than that of A. conyzoides. rm of S. nigrum and A. aspera was higher than that of A. conyzoides. Rd of P. acinosa was higher than that of A. conyzoides and A. aspera. The photosynthetic parameters (Pn max, Vc max, Jmax and rm) of woody species were significantly higher than those of herbaceous species, but no significant difference was found in Rd between woody and herbaceous species. In conclusion, the difference in photosynthetic capacity among different species and between the two plant life-forms resulted from the difference in Rubisco carboxylation capacity, electron transport capacity, and mesophyll resistance among these species.
    Quantitative apportionment of slope aspect and altitude to soil moisture and temperature and plant distribution on alpine meadow
    NIU Yu-jie, ZHOU Jian-wei, YANG Si-wei, WANG Gui-zhen, LIU Li, HUA Li-min
    2017, 28(5):  1489-1497.  doi:10.13287/j.1001-9332.201705.032
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    For understanding the effect of aspect and altitude of hill on soil moisture and temperature as well as the vegetation community, we selected an alpine meadow located on a hill in north-eastern Tibet Plateau as our study area. Data on soil moisture and temperature, as well as plant distribution pattern in this mountain ecosystem were collected. We used regression analysis, CCA ordination and variance decomposition, to determine the impacts of the key factors (aspect, altitude, soil temperature and moisture) on plant diversity distribution in 189 sample sites of the hill. The results showed that the plant diversity of shady aspect and bottomland was highest and lowest, respectively. The plant diversity of the shady aspect and on the ridge of the hill increased initially and then decreased with the increasing altitude, but the plant diversity of the sunny aspect increased with the increasing altitude. At 0-30 cm soil layer, the soil temperature of the sunny aspect was higher than that of other aspects, but the soil temperature at 0-20 cm soil layer did not change with the increa-sing altitude. The soil moisture of shady aspect was higher than that of other aspects, and increased with the increasing altitude. The aspect and altitude explained 100% of soil temperature changes and 51.8% of soil moisture variation. Aspect alone explained 72.2% of soil temperature variation and altitude alone explained 51.8% of soil moisture variation, which had the highest contribution rate individually. Most plants were distributed on the shady aspect and on the ridge, and at medium altitude. Sedges mainly grew on the shady aspect, while Gramineae grew on the sunny aspect, the ridge was an ecotone. Cyperaceae, Gramineae and Leguminosae were mainly distributed in low altitude zone. Hill aspect and altitude totally explained 28.6% of plant abundance variation, hill aspect alone explained 19.9% of plant abundance variation. The management of grassland production and ecological restoration in alpine meadow ecosystem should consider the effect of landform on soil and vegetation, and the hill aspect should be priority factor instead of altitude when planning management interventions.
    Growth adaptability of Zostera marina at different habitats of the Swan Lake in Rongcheng, China
    GUO Mei-yu, LI Wen-tao, YANG Xiao-long, ZHANG Xiu-mei, LIU Jian-ying, LI Chang-jun
    2017, 28(5):  1498-1506.  doi:10.13287/j.1001-9332.201705.035
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    Eelgrass (Zostera marina), a seagrass species widely distributed in the coastal regions of northern hemisphere, has suffered with a great decline due to a variety of anthropogenic and environmental stresses. In order to examine the adaptability of eelgrass to different environmental stresses, studies on the morphology and reproductive capacity of eelgrass had been carried out monthly from November 2014 to October 2015 at four different habitats of the Swan Lake, including patch area inintertidal area and subtidal area, eelgrass meadow edge, and eelgrass meadow area. The results showed significant spatio-temporal variations in the morphological parameters and branch frequency of eelgrass shoots at different habitats of the Swan Lake. The highest values of leaf length, leaf width, aboveground/belowground biomass, and internode length/diameter were observed in the meadow area, i.e., 78.54 cm, 7.93 mm, 7.03 and 3.88, respectively, while the highest branch frequency was observed in the meadow edge (88.4%). The plasticity index for aboveground/belowground biomass was higher (ranging from 0.77 to 0.92) at the four habitats, but those for the leaf width was slightly lower (ranging from 0.41 to 0.64). The number of spathes in each shoot showed no significant difference at different habitats, whereas the number of spathes per unit area was significantly different. Clonal reproduction was more dominant in meadow area than in the patch area where human disturbance was high.
    Soil fertility evaluation of artificial afforestation areas in Tibet, China
    LUO Hong, PUBU Dun-zhu, ZHU Xue-lin, WU Jian-pu
    2017, 28(5):  1507-1514.  doi:10.13287/j.1001-9332.201705.016
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    To master the soil fertility situation of afforestation areas, where trees would be planted, the soil samples of 524 afforestation areas were taken to test its nutrients in six prefectures of Tibet, and the soil fertility was analyzed by the method of modified Nemerow synthesis index. The results showed that the synthetic fertility index of afforestation areas was between 0.425 and 1.972 in Tibet. The numbers of afforestation areas with general level, barren level, and fecund level occupied 65.9%, 34.9% and 0.2%, respectively. The mean fertility index of each soil property was in the order of alkalytic nitrogen> pH > total nitrogen > available potassium > organic matter > available phosphorus > total phosphorus > total potassium, which was between 0.654 and 2.643. The fertility level of total nitrogen, alkalytic nitrogen was mostly at the fecund and very fecund level. That of available potassium, organic matter, and total phosphorus was mainly at the general level. That of available phosphorus and total potassium was mainly at barren level, and soil pH was at a proper level. The synthetic fertility index in different prefectures was in the order of Nyingchi > Qamdo > Shannan > Lhasa > Shigatse > Ngari, which of afforestation areas was at the barren level in Ngari, Shigatse and Lhasa. The synthetic fertility index of Qamdo and Nyingchi were at general level. The number of afforestation areas at general level or barren level was nearly same in Shannan. The soil fertility of afforestation areas was low in Tibet as a whole. The soil synthetic fertility and sub-fertility of soil properties became gradually good from the northwest (Ngari) to the southeast (Nyingchi), suggesting obvious horizontal zonality.
    Type and key drivers of nitrification for an acidic peat soil in Xiaoxing’an Mountain, China
    WANG Zhi-hui, SU Jing, JIANG Xian-jun
    2017, 28(5):  1515-1521.  doi:10.13287/j.1001-9332.201705.026
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    Acidic forest peat soil in Xiaoxing’an Mountain was used to investigate the type and key drivers of nitrification by carrying out nitrification incubation after adding 10 mL·L-1 C2H2 and different amounts of (NH4)2SO4(0, 1.2, 6.0 mmol N·kg-1). Results showed that strong mineralization (0.9-1.4 mg N·kg-1·d-1) and nitrification (0.4-0.6 mg N·kg-1·d-1) after 2 weeks of incubation were observed for both nitrogen and no nitrogen treatments, and no significant difference was observed for different (NH4)2SO4 application treatments. For C2H2 treatment, there was relatively stronger mineralization (0.8 mg N·kg-1·d-1), but no obvious nitrification (0 mg N·kg-1·d-1). These results indicated that the nitrification in acidic peat soil was mainly autotrophic, and inorganic nitrogen application did not affect nitrification rate significantly. Results also implied that the substrate (NH3) for nitrification was from the organic N mineralization, rather than the (NH4)2SO4 application. Both ammonia-oxidizing bacteria (AOB) and archaea (AOA) abundances increased significantly during 0-14 d regardless of nitrogen application. However, no significant difference in AOB and AOA abundances for different (NH4)2SO4 application treatments was observed, indicating that ammonia oxidizers did not respond positively to (NH4)2SO4 application. Compared with the treatments without C2H2, AOB and AOA abundances did not change significantly during the incubation in C2H2 treatment, suggesting that both AOA and AOB were likely the key players in nitrification in the acidic peat soil.
    Effects of invasive Cenchrus spinifex on nitrogen pools in sandy grassland
    ZHANG Ting, FU Wei-dong, ZHANG Rui-hai, SONG Zhen, BAI Chao, HUANG Cheng-cheng, ZHANG Guo-liang
    2017, 28(5):  1522-1532.  doi:10.13287/j.1001-9332.201705.040
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    Cenchrus spinifex is an invasive plant found in large areas of northern China. In this study, we focused on analysis of the effects of C. spinifex on soil nitrogen and plant nitrogen pools in Horqin sandy grassland. In addition, a pot experiment with 15N tracing techniques was designed to study the biological nitrogen fixation ability of C. spinifex, compared with two native grasses, Elymus dahuricus and Agropyron cristatum. The total soil nitrogen pool in C. spinifex invaded-area increased significantly by 47.5% and 20.8%, and the soil ammonium nitrogen pool decreased significantly by 25.6% and 25.2%, compared with those in bare and native plant Roegneria kamoji areas, respectively. The plant shoot nitrogen pool decreased significantly by 18.7% in C. spinifex compared with native plant R. kamoji. Atom% 15N, atom% 15N excess and atom% 15N weighting excess of C. spinifex were all significantly lower than those of E. dahuricus and A. cristatum. The nitrogen use efficiencies of C. spinifex and E. dahuricus were 48.5% and 47.0%, respectively, and no significant difference was observed. Ndfa of C. spinifex accounted for 60.2%, when growing together with E. dahuricus. These results suggested that the characteristics on the high efficient use for nitrogen of this invasive weed might an ecological adaptation mechanism, leading to successful colonization and spread in Horqin Steppe.
    Vertical distribution and seasonal variation of nitrogen, phosphorus elements in Spartina alterniflora wetland of Jiaozhou Bay, Shandong, China
    MIAO Ping, XIE Wen-xia, YU De-shuang, CHEN Jian-lei, GONG Jian
    2017, 28(5):  1533-1540.  doi:10.13287/j.1001-9332.201705.003
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    In order to study the vertical distribution and the seasonal variation of N and P in Spartina alterniflora wetland of Jiaozhou Bay, soil samples in S. alterniflora wetland and bare flat in April, July, September, October, November and December 2015 were collected, and TN, NH4+-N, TP, AP, TOC, pH, salinity and water content were tested. The average values of soil TN, NH4+-N, TP and AP contents in S. alterniflora wetland were 0.396 g·kg-1, 12.14 mg·kg-1, 0.385 g·kg-1 and 16.52 mg·kg-1 respectively, while those in bare flat were 0.419 g·kg-1, 8.13 mg·kg-1, 0.423 g·kg-1 and 19.57 mg·kg-1 respectively. Generally, they decreased gradually with the increase of the soil depth (0-60 cm). The contents of N and P in S. alterniflora wetland had obvious variations with season. The maximum and minimum of soil TN contents in S. alterniflora wetland were in spring and autumn respectively, while the content of soil TN in bare flat decreased with the change of season. Compared with the bare flat, the content of TP in S. alterniflora wetland had the opposite trend with the change of season, while that of AP had the same trend. The contents of TN and TP were significantly positively related with TOC, while there was no significant correlation between them in the bare flat. N and P contents in S. alterniflora wetland and bare flat were obviously influenced by pH and salinity.
    Changes of soil carbon, nitrogen and phosphorus and stoichiometry characteristics in marsh invaded by Spartina alterniflora
    JIN Bao-shi, YAN Hong-yuan, WANG Wei-qi, ZENG Cong-sheng
    2017, 28(5):  1541-1549.  doi:10.13287/j.1001-9332.201705.014
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    To clarify the effect of invasive alien plants on ecosystem functions, soil total carbon (TC), total carbon (TN), and total phosphorus (TP) contents were studied in the exotic invasive plant Spartina alterniflora marsh with different durations and the native species Cyperus malaccensis marsh in the Minjiang River estuary. The results showed that there were different variations of TC, TN and TP at 0-50 cm soil layer in the C. malaccensis marsh invaded by S. alterniflora, but the changes of TC and TN were similar and the change of the TP lagged behind them. Soil C/N increased continually with the increase of TC. Soil TP was a key factor affecting soil C/P and N/P during the S. alterniflora invasion, and the change of C/P and N/P followed a similar trend. The changes of TC, TN and TP were influenced by abiotic factors such as soil salinity, bulk density, soil water content and clay composition. C, N and P stoichiometric ratios were influenced mainly by soil salinity and grain composition. C/N and C/P were the good indicators for soil carbon enrichment ability in S. alterniflora marsh. S. alterniflora invasion induced the change of biomass and marsh habitats. Soil carbon, nitrogen, phosphorus contents, and their ecological stoichiometric ratios changed significantly in the C. malaccensis marsh invaded by S. alterniflora and showed diffe-rent change characteristics with different invasion duration.
    Effects of sewage sludge compost on the growth and element uptake of Neolamarckia cadamba seedlings
    CHU Shuang-shuang, TONG Xin, WANG Wen-rui, MO Qi-feng, CHEN Xiao-yang, ZENG Shu-cai
    2017, 28(5):  1550-1556.  doi:10.13287/j.1001-9332.201705.036
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    Sewage sludge compost (SSC) is rich in organic matter and nutrient elements indispensable to plant growth. Utilizing SSC as seedling growing substrate is generally recognized as a new ecological method for utilization of sewage sludge. We investigated impacts of SSC treatments including 0% (CK), 25% (T1), 50% (T2), 75% (T3), and 100% (T4) on the growth and nutrient uptake of Neolamarckia cadamba seedlings in a 7-month pot experiment. The changes in element contents in substrate after pot experiment were also addressed. Results showed the SSC treatments had significant impacts on the growth of N. cadamba seedlings. The seedlings in T4 treatment grew abnormally and all died in two weeks after transplanting. Seedling height, ground diameter and biomass in T1, T2 and T3 treatments were significantly higher than CK, with those in T2 being the best among all treatments. Seedlings in T2 and T3 treatments took up significantly more N, P, K, Cu, Zn, Pb and Cd, while those in T1 treatment absorbed significantly more N and Pb than CK. The heavy metal uptake amount of each treatment exhibited the order of Zn>Cu>Pb>Cd. At the end of the pot experiment, the contents of organic matter, N, P and K in growing substrate were still relatively high, and a certain portion of heavy metals still remained in the substrate, but with lower contents than the standards set for agricultural usage-oriented sewage sludge, indicating that the post-experiment substrate may be reused.
    β-glucan content spatial distribution characteristics and its influencing factors of cultivated barley in Qinghai-Tibet Plateau, China
    WANG Jian-lin, ZHONG Zhi-ming, FENG Xi-bo, FU Gang, YU Cheng-qun, HOU Wei-hai, WANG Gai-hua, Dacizhuoga
    2017, 28(5):  1557-1562.  doi:10.13287/j.1001-9332.201705.013
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    β-glucan content spatial distribution characteristics of cultivated barley in Qinghai-Tibet Plateau were investigated based on the data measured from 83 sampling sites. The results showed that β-glucan content exhibited a macrocosm pattern of spatial distribution along the horizontal direction in Qinghai-Tibet Plateau, with staggered patches of different values. Two regions of higher β-glucan content were observed with centers of Guide and Tongde in Qinghai Province and Xiahe and Hezuo in Gansu Province (northeast), and Jiangzi, Bailang, Xietongmen, Shigatse, Lazi, Kangma, Gongga and Qushui in Tibet (southwest). Along the vertical direction, β-glucan content distribution pattern appeared with double peak curves. There were two high value zones between the altitudes from 2700 m to 3000 m and from 3600 m to 3900 m, with average β-glucan content value of (5.7±1.7)% and (4.6±1.1)%, respectively. Influencing factors of β-glucan content with importance value index more than 40.0% were as follows: grain color > ear density > average relative humidity in September > soil available N content > soil available K content > average diurnal temperature range in June > ≥10 ℃ accumulated temperature > average annual temperature > soil available P content > average diurnal temperature range in September.
    Effects of continuous drought during different growth stages on maize and its quantitative relationship with yield loss
    MI Na, CAI Fu, ZHANG Yu-shu, JI Rui-peng, YU Wen-ying, ZHANG Shu-jie, FANG Yuan
    2017, 28(5):  1563-1570.  doi:10.13287/j.1001-9332.201705.025
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    To investigate the influences of continuous decline of soil water content during different growth stages on the growth, development and yield of maize, artificial water control experiment with a rainout shelter were conducted, and the dynamic variations of several physiological and ecological indices of maize were analyzed, including plant height, leaf area index (LAI), photosynthesis characteristics, aboveground biomass, and yield. The experimental factors considered in this field experiment were the starting time and duration of water control. Rainfall was sheltered from jointing with duration of 20 (T1) and 27 days (T2) and from heading with duration of 20 (T3) and 27 days (T4) for each starting time. In total, there were 5 treatments in this field experiment, including the treatment of control check (CK). The results indicated that LAI was reduced by conti-nuous drought with leaves rolling, tresses and early aging of lower leaves, thus biomass accumulation and grain yield were reduced. At the end of each treatment of continuous drought, LAI was reduced to 74.9%, 68.2%, 60.5% and 48.3% of the CK LAI for the T1 to T4 treatments, respectively. After experiencing continuous water control, the maximum photosynthetic rate (Pn max) of leaf decreased gradually, with Pn max decreased to 23% of the CK Pn max for the treatment T1 and T3, and to less than 10% of the CK Pn max for the treatment T2 and T4 at the end of each treatment. Two weeks after re-watering, Pn max recovered to around 90% of the CK Pn max. Compared with CK, grain yield decreased by 18.5% and 24.0% for the T1 and T2 treatments, and by 46.1% and 45.8% for the T3 and T4 treatments, respectively. Continuous drought brought about more serious effects during heading period than during jointing period on aboveground biomass and yield components. The drought condition of soil could be represented by drought degree (D), which was linearly correlated with maize yield loss and could be used to predict the yield loss.
    Sink-source relationship of potato plants and its role involved in the reduction of tuber yield in continuous cropping system
    LIU Xing, QIU Hui-zhen, ZHANG Wen-ming, ZHANG Chun-hong, WANG Ya-fei, MA Xing
    2017, 28(5):  1571-1582.  doi:10.13287/j.1001-9332.201705.019
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    The Yellow River irrigation area in middle Gansu Province is one of the main production bases for processing potato and potato tuber seeds in China. However, continuous potato cropping (CPC), resulting from intensive cultivation, has been affecting the sound development of the potato industry. A long-term field experiment was carried out in order to reveal the mechanisms of CPC obstacles. Five treatments, with different years of continuous potato cropping, were designed marking as 0-5 a, 0 a was maize-potato rotation, used as the control (CK). The present study focused on how to change in sink size and sink activity as well as source activity of potato plants under CPC conditions, especially their roles involved in the reduction of tuber yield. There were no significant differences in tuber yield under short-term CPC (1-2 a) compared with CK, however, significant decline by 28.6%-32.8% occurred under long-term CPC (3-5 a), which was mainly derived from the decline in fresh mass of each tuber. Compared with CK, long-term CPC significantly decreased sink size by 38.4%-53.0%. In addition, long-term CPC not only postponed the potato development progress, by postponing the formation and development of potato tubers, but reduced dry matter accumulation in tubers as well. Long-term CPC significantly decreased source activity, showing that plant height, branch numbers per main stem, chlorophyll content, and dry-matter content of leaf were significantly lower than those of CK, besides, morphological development of root system was also restrained. Compared with CK, root vigor, ribulose diphosphate carboxylase (RuBP Case) and sucrose phosphate synthase (SPS) activities of leaves under long-term CPC significantly decreased by 28.6%-63.1%, 52.6%-64.6% and 26.3%-53.4%, respectively. Long-term CPC caused signi-ficant decline in production capability of source, consequently, reduced the production of assimilation product by a large margin, and contributed to the deficiency in translocation amount of assimilates into tuber during post-anthesis, which finally led to the reduction in tuber yield. In conclusion, the unbalance of sink-source relationship of potato plants was the main cause for CPC obstacles in the Yellow River irrigation area in middle Gansu Province.
    Effects of low-concentration Cry1Ac toxic protein on growth and reproduction of three successive generations of Sylepta derogata population
    ZHOU Hao, CAI Wen-chen, SU Hong-hua, YANG Yi-zhong
    2017, 28(5):  1583-1587.  doi:10.13287/j.1001-9332.201705.007
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    Cotton leaf roller Sylepta derogata causes serious damage to cotton at the later growing stages of cotton. A leaf-dip method was used to measure the effects of low-concentration CrylAc toxic protein on the development and population growth of three successive generations of cotton leaf rol-lers in this study. The larval duration of Bt-fed S. derogata was 1.78-2.00 d longer, adult life span 1.44-1.94 d longer, and pupal mass 5.3%-11.8% higher than those of the control, respectively. The egg counts per female in the three generations were 65.1%, 47.3% and 37.6% higher, respectively, than those of the control, and the indexes of population trend were 11.4%, 17.5% and 20.0% greater, respectively. No significant differences were found in the duration of pupa duration, the emergence rate, the sex ratio, or the hatch rate. It was suggested that the population of cotton leaf rollers would steadily increase during the later stage of transgenic Bt cotton growth, therefore, further risk assessments of transgenic cotton and comprehensive management of these pests in cotton fields were needed.
    Effects of exogenous melatonin on accumulation and chemical form of Cd in rice
    LIU Shi-xiang, HUANG Yi-zong, LUO Ze-jiao, HUANG Yong-chun, YANG Xiu-wen
    2017, 28(5):  1588-1594.  doi:10.13287/j.1001-9332.201705.027
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    Effects of exogenous melatonin on accumulation and chemical form of Cd in rice seedlings were investigated. The results showed that Cd stress significantly decreased the biomass of shoots and roots, and the chlorophyll content in rice leaves. The addition of exogenous melatonin could remarkably increase the biomass of rice and significantly decreased Cd content in the shoots and roots. At Cd concentration of 5 μmol·L-1, addition of 20 μmol·L-1 exogenous melatonin could decrease Cd content in rice shoots and roots by 48.4% and 16.9% respectively, compared with the control. When the concentration of exogenous melatonin rose to 100 μmol·L-1, Cd content in rice shoots and roots decreased by 67.5% and 47.9% respectively. Furthermore, the addition of exogenous melatonin obviously decreased the Cd-translocation efficiency of rice seedlings. When the Cd concentration was 20 μmol·L-1, addition of 20 and 100 μmol·L-1 exogenous melatonin could decrease the Cd-translocation efficiency by 24.4% and 46.8% respectively. The chemical form of Cd in rice seedlings was analyzed by using sequential extraction. The results showed that exogenous melatonin addition increased the proportion of NaCl-extractable Cd, while decreased the proportion of ethanol-extractable Cd and water-extractable Cd in rice seedlings. It was suggested that the addition of exogenous melatonin could promote the transfer of Cd from strong to weak mobility form, thereby reducing the uptake and transport of Cd in rice seedlings.
    Effects of different proportions of red and blue light on the growth and photosynthesis of tomato seedlings
    WANG Li-wei, LI Yan, XIN Guo-feng, WEI Min, MI Qing-hua, YANG Qi-chang
    2017, 28(5):  1595-1602.  doi:10.13287/j.1001-9332.201705.010
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    In order to explore the mechanism of response of growth and development of tomato seedlings to the combination of red and blue light, the light-emitting-diodes (LEDs) as precision modulation light sources were used in this study with 7 treatments including red (R) light, blue (B) light and combination of R+B light (9R1B, 6R1B, 3R1B, 1R1B, 1R3B), white (W) light as control, and the effects of different proportions of R and B light on the growth, photosynthetic pigment content, photosynthetic characteristics, chlorophyll fluorescence and root activity of tomato seedlings with variety of ‘SV0313TG’ as experiment material were studied. The results showed that there were significant differences in growth of tomato seedlings under treatments of different proportions of R and B light. The plant height, specific leaf area and intercellular CO2 concentration of tomato seedlings were significantly promoted by R light, while Fv/Fm and ΦPSⅡ were decreased, the root growth was inhibited as the root activity declined, so that the seedling index was reduced. The seedling growth was significantly suppressed under B light and the chlorophyll content was decreased, while the chlorophyll a/b was enhanced. Furthermore, combination of R+B light was be-neficial to the growth and development of tomato seedlings, and the plant dry mass, chlorophyll content and photosynthetic performance were significantly increased under 3R1B. In addition, seedlings grew strongly and had the highest value of seedling index under this treatment. In conclusion, the combination of R+B light could promote photosynthetic pigment content and photosynthetic efficiency in leaves of tomato seedlings, as well as plant growth, especially for treatment of 3R1B.
    Response and adaptation of photosynthesis of cucumber seedlings to high temperature stress
    SUN Sheng-nan, WANG Qiang, SUN Chen-chen, LIU Feng-jiao, BI Huan-gai, AI Xi-zhen
    2017, 28(5):  1603-1610.  doi:10.13287/j.1001-9332.201705.009
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    Cucumber seedlings (Cucumis sativus Jinyou 35) were used to study the effects of high temperature (HT: 42 ℃/32 ℃) and sub-high temperature (SHT: 35 ℃/25 ℃) on its photosynthesis and growth. The results showed that the growth of cucumber seedlings was dramatically inhibited by the high and sub-high temperature stresses. The photosynthetic rate (Pn) was gradually reduced, while intercellular CO2 concentration (Ci) was increased as heat stress lasted. Under heat stress, stomatal conductance (gs), transpiration rate (Tr), photorespiration rate (Pr) and dark respiration rate (Dr) showed a trend from rise to decline in cucumber seedlings, which implied that heat-induced decline of photosynthesis was mainly due to non-stomatal limitation. Maximal photochemical efficiency of PSⅡ in darkness (Fv/Fm), actual photochemical efficiency (ΦPS), photochemical quenching (qP) and electron transport rate (ETR) were severely hampered, while initial fluorescence (Fo) and non-chemical quenching (NPQ) were increased as a result of high and sub-high temperature stresses. Under extended high temperature stress, the activities of RuBP carboxylase (RuBPCase) and Rubisco activase (RCA) as well as the mRNA abundance of Rubisco and RCA were in the trend of decrease, while they were reduced 3 days following the sub-high temperature treatment. The activities and mRNA expressions of sedoheptulose-1,7-bisphosphatase (SBPase) and fructose 1,6-bisphosphate aldolase (FBA) increased initially, but decreased afterwards under heat stress. Taken together, our data suggested that short-term sub-high temperature did not cause photoinhibition under optimal light conditions, however, high temperature led to severe damage to PSⅡ reaction center in cucumber seedlings. The photosynthetic enzymes were induced by high temperature stress and the induction was affected by temperature and stress duration.
    Effects of fertilizing regime and planting age on soil calcium decline in Luochuan apple orchards
    LI Peng, LI Chun-yue, WANG Yi-quan, JIAO Cai-qiang
    2017, 28(5):  1611-1618.  doi:10.13287/j.1001-9332.201705.022
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    This study was conducted to assess the effects of fertilizing regime and orchard planting age on soil calcium contents and stocks in the apple orchards on the Loess Plateau. The apple orchards in Luochuan County, one of the best regions for apple plantation in the world, were selec-ted in this study. The contents of calcium carbonate,water-soluble calcium and exchangeable cal-cium at 0-100 cm soil layer under different fertilizing regimes and various planting ages were mea-sured, their stocks were calculated and their variation features were analyzed. The results showed that soil in the apple orchards in the study region was characterized by the decline in calcium contents. The decline was more serious in apple orchards with long-term application of chemical fertili-zer than in those with combined application of chemical fertilizer and farmyard manure. The average contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in apple orchards with long-term application of chemical fertilizer decreased by 38.8%, 25.4% and 5.6% respectively than those in the apple orchards with long-term application of both chemical fertilizer and farmyard manure. The stocks of calcium carbonate, water-soluble calcium and exchangeable calcium decreased by 36.4%, 26.0% and 4.3%, respectively. The decline of soil cal-cium was aggravated with the increase of orchard planting age. The contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in orchards of more than 25 years of planting age decreased by 48.8%, 69.4% and 39.5% respectively, compared with orchards of less than 10 years of planting age, and the stocks decreased by 40.8%, 64.1% and 33.0%, respectively. These results indicated that either long-term application of chemical fertilizer or long-term plantation of apple trees obviously depleted soil calcium carbonate, water-soluble calcium and exchangeable calcium. Therefore, it was recommended that application of chemical fertilizer and farmyard manure should be combined to mitigate soil calcium decline, and calcium management should be strengthened in apple orchards of more than 25 years of planting age. The fertilizing regime was a driving factor of soil calcium decline which had a significant temporal (orchard planting age) and spatial (soil depth) effect.
    Distribution characteristics of soil aggregates and their associated organic carbon in gravel-mulched land with different cultivation years
    DU Shao-ping, MA Zhong-ming, XUE Liang
    2017, 28(5):  1619-1625.  doi:10.13287/j.1001-9332.201705.020
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    The distribution characteristics of soil aggregates and their organic carbon in gravel-mulched land with different planting years (5, 10, 15, 20 and 30 years) were studied based on a long-term field trial. The results showed that the soil aggregate fraction showed a fluctuation (down-up-down) trend with the decrease of soil aggregate size. The soil aggregates were distributed mainly in the size of >5 mm for less than 10 years cultivation, and 0.05-0.25 mm for more than 15 years. The content of aggregates over 0.25 mm (R0.25) and the mean weight diameter (MWD) of soil aggregates all decreased with the increase of cultivation time. The content of organic carbon within soil aggregates increased with the decrease of soil aggregate size in gravel-mulched land with diffe-rent planting years. However, the content of organic carbon within soil aggregates, contribution rates of different aggregate fractions to soil organic carbon and soil organic carbon storage of aggregate fractions decreased with planting time extension and soil depth. Soil organic carbon in the aggregate sizes over 1 mm was sensitive to long term gravel-mulched field planting. Organic carbon storage of aggregate fractions with 10, 15, 20 and 30 years of planting decreased by 8.0%, 24.4%, 27.5% and 31.4% in the soil depth of 0-10 cm, and 1.4%, 15.8%, 19.4% and 21.8% in the soil depth of 10-20 cm, respectively. In conclusion, the ability of soil carbon sequestration in arid gravel-mulched field was reduced with planting time extension. Therefore, soil fertility of gravel-mulched fields which were cultivated for more than 15 years need to be improved.
    Distribution of soil organic carbon, total nitrogen, total phosphorus and water stable aggregates of cropland with different soil textures on the Loess Plateau, Northwest China
    GE Nan-nan, SHI Yun, YANG Xian-long, ZHANG Qing-yin, LI Xue-zhang, JIA Xiao-xu, SHAO Ming-an, WEI Xiao-rong
    2017, 28(5):  1626-1632.  doi:10.13287/j.1001-9332.201705.021
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    In this study, combined with field investigation and laboratory analyses, we assessed the distribution of soil organic carbon, nitrogen, phosphorous contents and their stoichiometric ratios, and the distribution of soil water stable aggregates along a soil texture gradient in the cropland of the Loess Plateau to understand the effect of soil texture and the regulation of soil aggregates on soil fertility in cropland. The results showed that, with the change from fine soils to coarse soils along the texture gradient (loam clay→ clay loam→ sandy loam), the contents of macroaggregates, organic carbon, nitrogen, phosphorous and their stoichiometric ratios decreased, while pH value and microaggregates content showed an opposite changing pattern. The contents of macroaggregates, organic carbon, nitrogen, phosphorous, and C/P and N/P were significantly increased, but pH value and microaggregates content were significantly decreased with increasing the soil clay content. Furthermore, the contents of organic carbon, nitrogen, phosphorous, and C/P and N/P increased with the increase of macroaggregates content. These results indicated that soil fertility in croplands at a regional scale was mainly determined by soil texture, and was regulated by soil macroaggregates.
    Transcriptome analysis of response to heavy metal Cd stress in soybean root
    ZHANG Xiao-na, PIAO Chun-lan, DONG You-kui, CUI Min-long
    2017, 28(5):  1633-1641.  doi:10.13287/j.1001-9332.201705.004
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    Cadmium (Cd) is a common pollutant not required for life activities, which can have extremely strong toxicity to organisms and affect the growth of crops at a low concentration in soil. To investigate the molecular mechanism of soybean root responding to Cd stress, 7-day old soybean seedlings were stressed by Cd (75 μmol·L-1) for 0 , 4 , 8, 12 and 48 h. Comparative transcriptome analysis showed 244, 1545, 442 and 1401 of genes responded to the four Cd treatments, respectively, and total 2670 differential expression genes were obtained. GO analysis classified these genes into 56 functional categories and COG analysis classified them into 25 functional categories. KEGG analysis showed that many genes involved in the phenylalanine metabolism, ubiquinone and other terpenoid-quinone biosynthesis and cysteine and methionine metabolism and so on. Further we found that expression of three isoflavones 2′-hydroxylase genes, two isoflavonereductase genes and a chalcone synthase gene were evidently up-regulated in all Cd treatments. The results of RT-PCR analysis of four DEGs were consistent with those of RNA-Seq data, further confirming the reliability of RNA-Seq results.
    Ecosystem services of Chongyi Hakka Terraces
    MIAO Jian-qun, WANG Zhi-qiang, YANG Wen-ting, SUN Song, HUANG Guo-qin
    2017, 28(5):  1642-1652.  doi:10.13287/j.1001-9332.201705.015
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    An economic evaluation of the main ecosystem services of Chongyi Hakka Terraces can help to demonstrate the contributions of the terrace system to Hakka society, on the basis of which the protection of Hakka Terrace system could be undertaken by the local government. In view of the social and economic characteristics of Chongyi Hakka Terrace ecosystem and its location, an index system was established to evaluate the service function, and a qualitative analysis was conducted for these functions and their importance. Besides, based on the data collected in 2014, with a combination of physical quality and economic value, a quantitative analysis was carried out for its nine ser-vice indicators. The findings were as follows: firstly, among the nine evaluation indicators, the phy-sical quality and the economic value of soil conservation both ranked the highest, the former being 76457 kg·hm-2 and the latter 105033 yuan·hm-2, accounting respectively for 72.2% and 30.0% of the total mass and total value of the Hakka Terrace ecosystem. Secondly, the unique service functions of Hakka Terrace ecosystem could be embodied in its cultural heritage and landscape, the corresponding economic values reaching up to 100000 yuan·hm-2 and 46333 yuan·hm-2 respectively, ranking the second and third highest among the nine indicators. Thirdly, the agricultural pro-ducts from the Hakka Terrace were vital welfare for the local residents, but their physical quality and the economic value only accounted for 6.1% and 10.4% of its total mass and total value respectively. As a result, the service functions of the Hakka Terrace ecosystem would be dramatically undervalued with respect to agricultural products only. These economic figures could reveal the huge contributions which the Hakka Terrace ecosystem had made to the society, not only raising awareness of the necessity to preserve the agricultural heritage by the administrators and the public, but also providing efficient data support for the government when making ecological compensation criteria for the Hakka Terrace system.
    Identification of the cumulative eco-environment effect of coal-electricity integration based on interpretative structural model
    HAN Lin-wei, FU Xiao, YAN Yan, WANG Chen-xing, WU Gang
    2017, 28(5):  1653-1660.  doi:10.13287/j.1001-9332.201705.008
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    In order to determine the cumulative eco-environmental effect of coal-electricity integration, we selected 29 eco-environmental factors including different development and construction activities of coal-electricity integration, soil, water, atmospheric conditions, biology, landscape, and ecology. Literature survey, expert questionnaire and interview were conducted to analyze the interactive relationships between different factors. The structure and correlations between the eco-environmental factors influenced by coal-electricity integration activities were analyzed using interpretive structural modeling (ISM) and the cumulative eco-environment effect of development and construction activities was determined. A research and evaluation framework for the cumulative eco-environmental effect was introduced in addition to specific evaluation and management needs. The results of this study would provide a theoretical and technical basis for planning and management of coal-electricity integration development activities.
    Effects of long-term fertilization on organic nitrogen fractions in aquic brown soil
    REN Jin-feng, ZHOU Hua, MA Qiang, XU Yong-gang, JIANG Chun-ming, PAN Fei-fei, YU Wan-tai
    2017, 28(5):  1661-1667.  doi:10.13287/j.1001-9332.201705.006
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    The purpose of present research was to investigate how different fertilization regimes altered soil organic nitrogen fractions and their inter-annual dynamics based on a series of long-term experiment (initiated at 1990), including: CK (non-fertilization); M (recycled pig manure); NPK (chemical fertilizer NPK); NPK + M (recycled pig manure with chemical fertilizer NPK). The results showed that soil organic nitrogen components under the different fertilization treatments presented contrastive patterns from the establishment the experiments to 2015. Generally, acid hydrolysable organic nitrogen content increased year by year. The amino acid nitrogen content under CK and NPK treatments consistently declined, although amino acid nitrogen for M and NPK+M treatments showed a increasing trend. These phenomena were probably ascribed to the utilization of soil amino acids by microbes. From 1990 to 2015, NPK treatment substantially elevated the content of acid-released ammonium nitrogen by 31.1% compared with CK (mean value across the experiment), and for the treatments using organic manure (M and NPK+M), the contents of all fractions of soil organic nitrogen increased. Notably, the increase magnitudes for NPK+M were more dramatic than those of M. These results demonstrated that combined use of organic and inorganic fertilizers could more effectively elevate soil organic nitrogen, subsequently helping to improve the capacity of soil nitrogen supply and enhance the soil fertility.
    Response of soil ciliate to diammonium phosphate addition in alpine meadow of southern Gansu, Northwest China
    NING Ying-zhi, WANG Ting-ting, WU Wei-ning, CHEN Ling-yun, DU Guo-zhen
    2017, 28(5):  1668-1678.  doi:10.13287/j.1001-9332.201705.030
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    In typical alpine meadow of southern Gansu Province, five sampling sites by fertilizer diammonium phosphate (DAP) addition ranging from 0 g·m-2 to 120 g·m-2 were set in order to examine the response of soil ciliate communities to different concentrations of DAP. An investigation on the abundance and species richness of soil ciliates was carried out by non-flooded Petri dish, observation in vivo and three-level ten-fold dilution methods. Soil physicochemical factors including soil water content, pH value, contents of soil total nitrogen, total phosphorus and organic carbon at different sites were also measured. It was found that there was a total of 129 species belonging to 9 classes, 17 orders, 31 families and 46 genera. Lower species richness and diversity but higher ciliate abundance were observed in the soils with higher concentrations of DAP compared with the control. The dominant group Haptorida was substituted by Colpodida from the control to the soils with the increase of fertilizer application. The results of redundancy analysis indicated that the gradient changes of total phosphorus, soil temperature and water content were the main driving factors for the change of soil ciliate community distribution.
    Population genetic structure of Isaria cicadae causing enzootic of cicadas nymphs
    ZHANG Sheng-li, YU Shi-jun, LUAN Feng-gang, PU Shun-chang, CHEN Xue, LI Zeng-zhi
    2017, 28(5):  1679-1686.  doi:10.13287/j.1001-9332.201705.005
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    The population genetic structure of Isaria cicadae, which caused enzootic of cicadas nymphs in three regions, was analyzed by ISSR marker. The results showed that all three enzootic populations showed high genetic diversity with the highest in the Jingtingshan population and the lowest in the Shitai population. The UPGMA clustering analysis revealed that different enzootic populations did not have a predominant lineage but were polyphyletic and heterogeneous. Genetic lineages had nothing to do with geographical origin. However, two subpopulations of Jingtingshan from different sampling periods were gathered into different clades, which exhibited remarkable temporal heterogeneity. The genetic differentiation (Gst) among populations (subpopulations) was 0.2153 and the gene flow was low at 0.9110 (Nm<1), which indicated the low gene flow was one of the main reasons for the genetic variation in the population. Therefore, high heterogeneity and low dominance might be genetic structure characteristics of I. cicadae population causing enzootic of cicada nymphs.
    Effects of temperature increase on zooplankton size spectra in thermal discharge seawaters near a power plant, China
    YU Jing, ZHU Yi-feng, DAI Mei-xia, LIN Xia, MAO Shuo-qian
    2017, 28(5):  1687-1698.  doi:10.13287/j.1001-9332.201705.002
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    Utilizing the plankton Ⅰ (505 μm), Ⅱ (160 μm), Ⅲ (77 μm) nets to seasonally collect zooplankton samples at 10 stations and the corresponding abundance data was obtained. Based on individual zooplankton biovolume, size groups were classified to test the changes in spatiotemporal characteristics of both Sheldon and normalized biovolume size spectra in thermal discharge seawaters near the Guohua Power Plant, so as to explore the effects of temperature increase on zooplankton size spectra in the seawaters. The results showed that the individual biovolume of zooplankton ranged from 0.00012 to 127.0 mm3·ind-1, which could be divided into 21 size groups, and corresponding logarithmic ranges were from -13.06 to 6.99. According to Sheldon size spectra, the predominant species to form main peaks of the size spectrum in different months were Copepodite larvae, Centropages mcmurrichi, Calanus sinicus, fish larvae, Sagitta bedoti, Sagitta nagae and Pleurobrachia globosa, and minor peaks mostly consisted of individuals with smaller larvae, Cyclops and Paracalanus aculeatus. In different warming sections, Copepodite larvae, fish eggs and Cyclops were mostly unaffected by the temperature increase, while the macrozooplankton such as S. bedoti, S. nagae, P. globosa, C. sinicus and Beroe cucumis had an obvious tendency to avoid the outfall of the power plant. Based on the results of normalized size spectra, the intercepts from low to high occurred in November, February, May and August, respectively. At the same time, the minimum slope was found in February, and similarly bigger slopes were observed in May and August. These results indicated that the proportion of small zooplankton was highest in February, while the proportions of the meso- and macro-zooplankton were relatively high in May and August. Among different sections, the slope in the 0.2 km section was minimum, which increased with the increase of section distance to the outfall. The result obviously demonstrated that the closer the distance was from outfall of the power plant, the smaller the zooplankton became. On the whole, the average intercept of normalized size spectrum in Xiangshan Bay was 4.68, and the slope was -0.655.
    Niche and interspecific association of the dominant fish in the south coastal waters of Wenzhou, China
    DONG Jing-rui, SHUI Bo-nian, HU Cheng-ye, SHUI Yu-yue, DU Xiao, TIAN Kuo
    2017, 28(5):  1699-1706.  doi:10.13287/j.1001-9332.201705.028
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    The studies about the niche and interspecific association in China were mainly focused on the plants, birds and marine animals, and seldom on fish. Based on the fishery resources survey in spring (May) and autumn (September) in 2015, the associations among major fish species in south coastal waters of Wenzhou were investigated. The methods including niche breadth, niche overlap, variance ratio (VR), χ2-test, association coefficient (AC), percentage of co-occurrence (PC) and point correlation coefficients (Ф) were used. The results showed that 47 fish species were identified, including 9 orders, 27 families and 41 genera. Four species were dominant species and 9 were important species, which together accounted for 17%. The niche breadth cluster analysis demonstrated two clearly identifiable ecological niches. The first one referred to wide niche that included Harpodon nehereus, Collichthys lucidus, Engraulis japonicas, Pampus echinogaster, Argyrosomus argentatus, Polynemus sextarius, Decapterus maruadsi and Trichiurus haumela, and the second one was narrow niche that included Muraenesox cinereus, Amblychaeturichthys hexanema, Cunoglossus robustus, Pseudosciaena polyactis and Ilisha elongate. The niche overlap value of the main fish was 0-0.90, indicating that there was difference in the resource utilization among the species. The ecological niche widths of C. robustus and M. cinereus were narrow, and the overlap values were high. This indicated that there was competition between these two species. The VR analysis revealed significant positive correlation among the main fish species. In view of the advantages of Ф value, which could reduce the impact of the analysis results of χ2-test, AC and PC to the interspecific association, the Ф value method was selected in this study, and the association of 63 couples were positive. Both the interspecific association and ecological niche had different degrees of correlation with the stability of community structure and community succession.
    Influence of methane and trichloroethylene domestication on bacterial community structure in landfill cover soil.
    ZHAO Tian-tao, HE Zhi, ZHANG Li-jie, XING Zhi-lin, GAO Yan-hui, PENG Xu-ya
    2017, 28(5):  1707-1715.  doi:10.13287/j.1001-9332.201705.012
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    The biological oxidation capacity and change of microbial community structure of typical landfill cover soil cultured in situ by methane and trichloroethylene (TCE) were studied. The rates of CH4 oxidation and TCE degradation were 0.20-0.87 μmol·g-1 soil·h-1 and 0.009-0.013 mg·L-1·h-1 among these landfill cover soils, respectively. The activity of CH4 oxidation in Shandong landfill cover soil was higher than that in landfill cover soils sampled from Guangdong, Shanghai and Chongqing. The α-diversity and microbial community structure before and after co-metabolism degradation were then investigated in all landfill cover soils by Illumina MiSeq sequencing. The results indicated that bacterial Operational Taxonomic Units (OTUs) were assigned to 39 phyla, 85 classes and 562 genera in all the commented OTUs clustering. The dominant bacterial populations were Proteobacteria, Bacteroidetes, Chloroflexi and Acidobacteria and the sum of the proportion was over 77.4% in all landfill cover soils. In addition, total percent of γ-Protebacteria, β--Protebacteria, α-Proteobacteria, Actinobacteria and Acidobacteria was over 26.5%. Specifically, the relative abundances of Methylophilaceae_uncultured, Anaerolineaceae_uncultured, Arthrobacter and Pseudomonas increased obviously after acclimated by TCE. These results suggested that there were co-metabolism degradation with non-methane compounds and aerobic assimilation of TCE besides the widely-agreed co-metabolism degradation by methanotrophs.
    Effects of disturbances on animal-mediated seed dispersal effectiveness of forest plants: A review
    WANG Jing, YAN Qiao-ling
    2017, 28(5):  1716-1726.  doi:10.13287/j.1001-9332.201705.033
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    Disturbances commonly exist in forest ecosystems and play a critical role in the forest regeneration and succession. Animal-mediated seed dispersal is an essential stage of seed regeneration for most plants. To some extent, the responses of animal-mediated seed dispersal to forest disturbances can predict the changes in community composition and structure, and consequently, the succession direction of forests. In the present study, we systematically discussed the ecological significance of the effects of disturbances on animal-mediated seed dispersal effectiveness (i.e., quantity and quality of seed dispersal) of forest plants. We also revealed the research progresses on the effects of natural disturbances (e.g., fire and forest gaps) and human disturbances (e.g., habitat fragmentation, hunting and logging) on the seed dispersal quantity, distance and seedling rege-neration after seed dispersal. The responses of seed dispersal quantity to disturbances were embodied in the dynamic changes of animal population. In addition, there was a slightly negative correlation between seed dispersal distance and interference. However, it was much more complicated for the influences of disturbance on seedling regeneration due to the various types of disturbances, and the environmental factors in disturbed areas also affected seed germination and seedling regeneration after seed dispersal. There were some problems of the study on the effects of disturbances on animal-mediated seed dispersal effectiveness of forest plants. Little was known about the effects of recovery processes of fire disturbance region and positive disturbances (e.g., tending, thinning and forest gaps) on the seed dispersal effectiveness, especially in the temperate forest ecosystems. In the future, long-term research on seed dispersal effectiveness of forest plants by animals after disturbances should be carried out, and the effects of positive disturbances on animal-mediated seed dispersal should be emphasized for the forest regions prone to disturbance.
    Reviews
    Applications of eco-environmental big data: Progress and prospect
    ZHAO Miao-miao, ZHAO Shi-cheng, ZHANG Li-yun, ZHAO Fen, SHAO Rui, LIU Li-xiang, ZHAO Hai-feng, XU Ming
    2017, 28(5):  1727-1734.  doi:10.13287/j.1001-9332.201705.001
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    With the advance of internet and wireless communication technology, the fields of ecology and environment have entered a new digital era with the amount of data growing explosively and big data technologies attracting more and more attention. The eco-environmental big data is based airborne and space-/land-based observations of ecological and environmental factors and its ultimate goal is to integrate multi-source and multi-scale data for information mining by taking advantages of cloud computation, artificial intelligence, and modeling technologies. In comparison with other fields, the eco-environmental big data has its own characteristics, such as diverse data formats and sources, data collected with various protocols and standards, and serving different clients and organizations with special requirements. Big data technology has been applied worldwide in ecological and environmental fields including global climate prediction, ecological network observation and modeling, and regional air pollution control. The development of eco-environmental big data in China is facing many problems, such as data sharing issues, outdated monitoring facilities and techno-logies, and insufficient data mining capacity. Despite all this, big data technology is critical to solving eco-environmental problems, improving prediction and warning accuracy on eco-environmental catastrophes, and boosting scientific research in the field in China. We expected that the eco-environmental big data would contribute significantly to policy making and environmental services and management, and thus the sustainable development and eco-civilization construction in China in the coming decades.
    Bacterial quorum sensing: Cooperation and cheating
    LAI Bai-min, WANG Mei-zhen, SHEN Dong-sheng
    2017, 28(5):  1735-1742.  doi:10.13287/j.1001-9332.201705.018
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    Quorum sensing (QS), a cell-to-cell communication, regulates a variety of social beha-viors, such as biofilm formation, public goods produce and gene horizontal transfer of bacteria. In the process of quorum sensing, public goods could be utilized by any members in the population, which was termed as cooperation. Notably, public goods also could be shared by the individuals who could not produce them, which was termed as cheating. Once cheaters come up, they possibly maintain equilibrium with cooperators, meanwhile they also possibly induce the collapse of population due to their rapid growth and shortage of public goods. Therefore, invasion of cheaters arouses wide attentions in medicine, agriculture, food science and so on regarded as a new strategy to control pathogens. In this study, based on the introduction about the theory of bacterial quorum sensing cooperation and cheating, we analyzed the factors influencing the formation and development of the relationship between cooperator and cheater. Moreover, we discussed the mechanism of stabilization in the relationship between cooperator and cheater, including kin selection, metabolic prudence, metabolic constraint (gene pleiotropy) and policing quorum sensing. Finally, some problems in current researches of quorum sensing cooperation and cheating were presented as well as the future research directions. We hoped this paper could deepen the understanding of bacterial quorum sen-sing and ecology of bacterial population.