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Table of Content

    20 September 2018, Volume 29 Issue 9
    Responses of soil nitrogen transformation to long-term nitrogen fertilization and precipitation changes in a broad-leaved Korean pine forest in Changbai Mountains, China.
    XU Ting-ting, ZHENG Jun-qiang, HAN Shi-jie, ZHANG Feng-li, WANG Xiu-xiu
    2018, 29(9):  2797-2807.  doi:10.13287/j.1001-9332.201809.018
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    Soil nitrogen (N) cycling, one of the most important biogeochemical processes in forest ecosystems, has significant environmental effects. However, little is known about how it responds to N deposition and precipitation changes. Here, we examined the main effects of N deposition (NF), rainfall reduction (RR) and their interactive effect (RF) on soil N cycling by N addition and transparent V-shaped board interception in a broad-leaved Korean pine forest in Changbai Mountains. The responses of soil nitrification, denitrification, nitrifying functional genes (ammonia-oxidizing archaea AOA and ammonia-oxidizing bacteria AOB), denitrifying functional genes (nirK, nirS and nosZ) and N fixing function genes (nifH) to NF, RR and RF treatments were analyzed. We found significant positive correlations between nitrification and soil NH4+-N, denitrification and and NO3--N, respectively. Soil nitrification and denitrification were not significantly influenced by the three treatments, while denitrification showed an obvious seasonal dynamics. Long-term RR treatment inhibited soil net nitrification, while NF and RF treatments promoted soil net nitrification; nifH and nosZ genes of bacteria were strong resistant to stress, and their diversity was not susceptible to the changes of N and rainfall. Under drought condition, nirK gene of soil bacteria was more susceptible to N deposition. AOA had a higher sensitivity to drought, while AOB had higher sensitivity to NF and RF treatments. The three treatments affected soil net nitrification and altered the diversity of AOB, AOA and nirK-harboring denitrifier in varying degrees, which might affect the release of N-containing gas and ecosystem services.
    Spatio-temporal variations and influencing factors of thermal comfort at different elevations.
    ZHANG Xi-yue, JIANG Chao, SUN Jian-xin, ZHOU Ming-fei
    2018, 29(9):  2808-2818.  doi:10.13287/j.1001-9332.201809.009
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    Thermal comfort is one of the ways assessing heat changes in climate change scenarios. Based on the daily observation data of 84 meteorological stations from Guizhou Province, the universal thermal climate index (UTCI) was used to examine the spatio-temporal variations and main influencing factors of thermal comfort at different elevations under the scenarios of climate change. Moreover, the impacts of different climatic factors on UTCI at different elevations were quantitatively analyzed. The results showed that the spatial distribution of annual UTCI in Guizhou Province had a strong consistency with that of annual temperature, which was decreasing with the increased elevation. The number of thermally comfortable days in most parts of the province was between 180 d and 240 d. UTCI increased with the increases of elevation, with the overall trends of UTCI [-0.58-1.38 ℃·(10 a)-1] being higher than the trends of temperature [-0.36-0.45 ℃·(10 a)-1] from 1984 to 2013. In general, the correlation coefficients between UTCI and climatic factors air tempe-rature, wind speed, atmosphere pressure, relative humidity and cloud cover were 0.899, -0.855, 0.818, -0.373, and -0.042, respectively. The correlations between climatic factors and UTCI varied across different elevations. The UTCI was affected lightly by air temperature and heavily by wind speed with increasing elevation.
    Relationship between vegetation C, N, P stoichiometry and species diversity in sand land.
    YANG Xiang-xiang, LI Meng-qi, HE Xing-dong, WANG Xue-zeng, YOU Wan-xue, YU Dian, ZHANG Cai-hua, CHEN Na
    2018, 29(9):  2819-2824.  doi:10.13287/j.1001-9332.201809.016
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    Vegetation stoichiometry represents plant nutrition limitation status. Whether it can affect the species diversity of plant community remains to be explored. In this study, we examined plant carbon (C), nitrogen (N), phosphorus (P) concentrations and stoichiometry, and further analyzed the relationship between stoichiometry and species diversity in Artemisia ordosica community and Salix psammophila community in sand land of the Ningxia Habahu National Nature Reserve. The results showed that, for the S. psammophila community growing in mobile and semi-fixed sand dunes, there was a significant negative correlation between Simpson index and vegetation C/N ratio, but no significant correlation between Simpson index and vegetation N/P ratio. For A. ordosica community distributed in semi-fixed and fixed dunes, the Shannon index had a significant positive correlation with vegetation N/P ratio and a significant negative correlation with vegetation C/N ratio. Combined the vegetation stoichiometry with the results of regression analysis (RDA), P concentration and thus N/P ratio had different influences on the species diversity for A. ordosica community and S. psammophila community. Our results showed that vegetation stoichiometry has an important influence on species diversity of plant community in sand land.
    Stand-level biomass estimation models for the tree layer of main forest types in East Daxing’an Mountains, China.
    DONG Li-hu, LI Feng-ri
    2018, 29(9):  2825-2834.  doi:10.13287/j.1001-9332.201809.014
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    Forest biomass estimation methods of regional scale attract most attention of the resear-chers, with developing stand-level biomass model being a research trend. Based on the biomass data from fix forest types, two additive systems of biomass equations based one- and two-variable were developed. The model error structure (additive vs. multiplicative) of the allometric equation was evaluated using the likelihood analysis. The nonlinear seemingly unrelated regression (NSUR) was used to estimate the parameters in the additive system of stand-level biomass equations. The results showed that the assumption of multiplicative error structure was strongly supported for the stand-level biomass equations of total and components for those forest types. Thus, the additive system of log-transformed biomass equations was developed. The adjusted coefficient of determination of the additive system of biomass equations was 0.78-0.99, the mean relative error was between -2.3%-6.9%, and the mean absolute relative error was between 6.3%-43.3%. Adding mean tree height in the additive systems of biomass equations could significantly improve the model fitting performance and predicting precision for most of the models. The biomass equations of total, aboveground and stem were better than biomass equations of root, branch, foliage and crown. In order to estimate model parameters more effectively, the additivity property of estimating tree total, sub-totals, and component biomass should be taken into account. Overall, the stand-level biomass models established in this study would be suitable for predicting stand-level biomass of six forest types in Daxing’an mountains.
    Hyperspectral prediction model of soil nutrient content in the loess hilly-gully region, China.
    ZHANG Chao, LIU Yong-mei, SUN Ya-nan, WANG Lei, LIU Jian-hong
    2018, 29(9):  2835-2842.  doi:10.13287/j.1001-9332.201809.010
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    Rapid and accurate estimation of soil nutrient content based on hyperspectral data is an optimal method for the monitoring of soil nutrient and inversion of soil physical and chemical characters. The relationship between soil nutrient content and spectral reflectance was analyzed with soil samples being collected from the loess hilly-gully region of northern Shaanxi Province. The prediction models of the content of soil organic matter, total nitrogen, total phosphorus and total potassium were constructed by the combination of three techniques, including partial least squares (PLS), multiple linear regression (MLR), and support vector machine (SVM). Then, the optimal model was selected by comparison analysis. The results showed good correlations between the content of soil nutrients and spectral reflectance in visible region (400-760 nm) and near infrared region (760-1100 nm). The maximum values of correlation coefficient located in both spectral regions. The SPA-SVM model had the best applicability and highest inversion accuracy for the contents of all soil nutrients, with simple and efficient modeling process. Our results provided a reference for applying machine learning algorithm in the construction of hyperspectral prediction model of soil nutrient content in the loess hilly-gully region.
    Predicting models of leaf area for trees in Larix olgensis plantation.
    XIE Long-fei, DONG Li-hu, LI Feng-ri
    2018, 29(9):  2843-2851.  doi:10.13287/j.1001-9332.201809.011
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    Leaf area influences dry matter production of trees, as well as the growth of trees and forest stands. The accurate estimation of leaf area plays an important role in analyzing the growth of trees and forest stands. Based on data of 76 Larix olgensis trees in a plantation of Heilongjiang Province, predicting models of branch leaf area (BLA) and crown leaf area (CLA) were constructed, respectively. The results showed that a form of lnBLA=β1+(β2+b2)lnBD+(β3+b3)lnRDINC+β4lnDBH+β5lnHT/DBH+(β6+b6)lnCR was selected as the optimal BLA mixed-effect model with the considera-tion of tree-level random effects, composed of three random-effect on lnBD, lnRDINC and lnCR (βi represented model fixed parameters, bi represented model random-effect parameters, BD was branch diameter, RDINC was the relative depth into crown from tree apex, DBH was tree diameter at breast height, HT/DBH represented the ratio of tree height to DBH, and CR represented the ratio of crown length to tree height). The adjusted coefficient of determination (Ra2), residual mean squares error (RMSE), mean error (ME), mean absolute error (MAE) and precision estimation (P) of the optimal BLA mixed model were 0.90, 0.5477, -0.03, 0.24 and 91%, respectively, indicating the model had a good performance in predicting. The CLA was calculated by predicted values of all branches based on developed BLA model and the final form of CLA model was as follows: lnCLA=γ0+γ1lnDBH+γ2CR (γi, model parameters). Results of likelihood ratio test (P>0.05) showed that plot-level random effect had no influence on the model performance, which can be ignored. The CLA model got a good-fitting effect with R2 and RMSE being 0.87 and 0.3847, respectively. The CLA predicting model developed in this study could provide a good prediction of CLA for L. olgensis trees and provided a theoretical basis for the research on distribution of leaf area and photosynthesis.
    Landscape pattern analysis and optimum design of park green space in Nanchang City, China based on GIS.
    WEI Xu-ying, CAI Jun-huo, YE Ying-cong, ZHOU Yang, LIU Chun-qing
    2018, 29(9):  2852-2860.  doi:10.13287/j.1001-9332.201809.007
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    Based on the current map data of park green space in the main urban area of Nanchang, the spatial database of park green space was set up with GIS technique, with the corresponding landscape indices being calculated by FRAGSTATS, the software of landscape pattern. Based on analyzing current landscape pattern of green space in Nanchang, the optimization strategy and scheme were proposed and the optimized landscape pattern was evaluated. The results indicated that the spatial distribution of patches in current park green space was uneven and area discrepancy was large, which is especially true in densely populated areas with less patch number of park green space and obviously low available area for disaster shelter. By substantially increasing the quantity and area of patches, improving the inter-patch connectivity, and increasing landscape fragmentation index appropriately, the “point-line-plane” pattern of park green space system in Nanchang would be optimized and the spatial distribution would be more rational, which could effectively enhance its role in biodiversity conservation, disaster prevention, and risk avoidance. The optimized indices of patch diversity, evenness and aggregation would be significantly increased, the dominance index would be reduced, and the landscape diversity would be more abundant.
    A multi-scale study on the formation mechanism and main controlling factors of urban thermal field based on urban big data.
    LUAN Xia-li, WEI Sheng, HAN Shan-rui, LI Xiao-ting, YANG Wen-yu, LIU Mao-song, XU Chi
    2018, 29(9):  2861-2868.  doi:10.13287/j.1001-9332.201809.015
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    The composition and structure of urban landscape and human activity intensity are key factors shaping urban thermal fields, whereas the relative importance of influencing factors for urban thermal distribution remains unclear. We carried out a case study in Yixing City. Land surface temperature (LST), ecological infrastructure (including vegetation and water cover), building volume and point of interest data were extracted from the RS interpretation, field mapping and programming technique. Using Pearson correlation analysis, univariete regression analysis, multiple regression analysis and relative weight analysis, we quantitatively analyzed the relationships between urban land surface temperature to ecological infrastructure, building volume, POI density at multiple scales (500, 1000, 2000 m) as well as their relative importance. The results showed that ecological infrastructure had a significant cooling effect, and the building volume and POI density were positively correlated with LST. Among the influence factors of urban heat field, ecological infrastructure had the highest relative weight (21.3%-43.8%), followed by building volume (20.7%-22.6%) and POI density (13.7%-21.7%). Our results would help to understand the relative importance of factors driving urban thermal field and offer important reference for taking mitigation measures to alleviate urban heat island effect.
    Relationship between land use and nutrients in surface runoff in upper catchment of Miyun Reservior, China.
    XU Er-qi, ZHANG Hong-qi
    2018, 29(9):  2869-2878.  doi:10.13287/j.1001-9332.201809.012
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    Quantifying the relationship between the land use and water nutrient concentrations would help guide land use management and water eutrophication control. Previous studies mainly focus on the quantitative structure of land use and lack a comprehensive characterization of the intensity and spatial distribution of land use. Taking the upper catchment of Miyun Reservoir as the study area, we analyzed the impacts of land use on surface runoff nutrient concentrations. We set 52 water quality monitoring sites within sub-basins of the entire upper catchment of Miyun Reservoir and collected water samples in each month. Using the remote sensing interpretation and spatial analy-sis techniques, land use information was extracted, which included the intensity, slope, distance to the rivers and sampling sites, and spatial arrangement. The land use information was used as independent variables for the multiple regression models to predict the changes of total nitrogen, total phosphorus and chemical oxygen demand concentrations. The consideration of the above four aspects of land use information significantly promoted the explanatory capability of models, with the coefficients of determination of multiple linear regression models changing from 0.294, 0.471 and 0.223 to 0.532, 0.685 and 0.489, respectively. We also compared the mean cumulative contribution rates of land use to nutrients and the corresponding cumulative area percentages with different flow path distances to river. Results showed that the flowing migration path distance to the river in the range of one kilometer was the key area to control water eutrophication in the upper catchment of Miyun Reservoir. Finally, we proposed three measures to control and regulate the water eutrophication, including optimizing the farmland fertilizer management, strengthening the livestock manure handling, building forested filter strips and riparian buffer zones.
    Impacts of climate and land use change on water and sediment load in the Northwest arid region, China: With Xiaonanchuan River Basin as a case.
    WANG Rui, YAO Zhi-jun, LIU Zhao-fei
    2018, 29(9):  2879-2889.  doi:10.13287/j.1001-9332.201809.020
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    Understanding regional water and sediment transport patterns and their responses to climate and land use changes can provide a theoretical basis for the prevention and control of soil erosion, and is an important prerequisite for the integrated development of land and water resources. Based on monthly monitoring meteorological, runoff, and sediment data from 1963 to 2013, combined with the land use data in the 1980s and 2000 and NDVI data, using the Mann-Kendall trend analysis and abrupt change test method, we systematically analyzed the long-term variations of the climate, runoff and sediment transport, with the changes of land use and vegetation coverage being identified in the Xiaonanchuan (XNC) River basin, a typical watershed in the Northwest arid region. Based on the analysis of single element change, the impacts of climate and land use change on water and sediment transport were quantified by the multiple linear regression analysis. Simultaneously, the key action factors were identified. Results showed that air temperature was developing to the polarization, the precipitation increased gradually. A generally warm and wet tendency of climate change and an increased frequency of extreme climate events were found in the XNC River basin. Moreover, the speed and magnitude of climate change were intensified after the 1990s, which was the abrupt change point of the climate. Since the 1980s, with economic and social development, the area of arable land and built land expanded, that of the forest area increased, and the ecological environments were improved in the XNC River basin. Under the dominant driving effects of land use and vegetation coverage change, the runoff and sediment load gradually reduced with the average rate of 1.7×106 m3·(10 a)-1 and 1.5×108 m3·(10 a)-1, respectively. Quantifying the influence of land use and climate change on the water and sediment transport indicated that vegetation cove-rage and mean daily maximum temperature were the two key factors affecting the runoff change, while the vegetation coverage and maximum daily precipitation were the two key factors affecting the sediment load change. Under the condition of current climate change, ecological restoration could be one of the most effective ways to prevent water and soil losses in the arid area.
    Effects of land use change on soil organic carbon and total nitrogen storage in Karst immigration regions of Guangxi Province, China.
    TONG Jin-hui, HU Ye-cui, DU Zhang-liu, ZUO Yu-qiang, LI Yu-ying
    2018, 29(9):  2890-2896.  doi:10.13287/j.1001-9332.201809.019
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    Land use change is an important factor affecting soil carbon and nitrogen cycle, and this is a hot spot in the study of global climate change. Based on the fixed depth method (FD) and the equivalent mass method (ESM), we explored the effects of land use change on soil organic carbon (SOC) and total nitrogen (TN) storage from the perspectives of forest reclamation and farmland vegetation restoration in Karst area. The storage of SOC and TN significantly decreased after the fore-sts were converted to grassland, eucalyptus and farmland. On average, the SOC and TN losses calculated by the FD method were 47.4% and 41.6%, respectively, the losses of SOC and TN calculated by ESM method were 54.8% and 49.7%. The SOC and TN storage increased significantly after abandonment of farmland to grassland or planting eucalyptus. On average, the SOC and TN stocks calculated based on the FD method increased by 60.5% and 49.7%, while the SOC and TN calculated by the ESM method increased by 85.5% and 70.8% respectively. The difference between FD method and ESM method was analyzed, it was concluded that FD method ignored the difference of soil bulk density after land use change. Soil bulk density was significantly increased after forest destruction. The loss of SOC and TN storage was overestimated by the FD method. Soil bulk density decreased after vegetation restoration, FD method will underestimate the enhancement of SOC and TN storage. It is suggested that the ESM method should be used to estimate the impacts of land use change on SOC and TN storage.
    Assessment of ecological vulnerability in multi-scale and its spatial correlation: A case study of Bailongjiang Watershed in Gansu Province, China.
    ZHANG Jin-xi, LI Hong-ying, CAO Er-jia, GONG Jie
    2018, 29(9):  2897-2906.  doi:10.13287/j.1001-9332.201809.008
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    The study of ecological vulnerability is of great significance to regional ecological environment protection and sustainable development. Bailongjiang Watershed (BLJW) of Gansu Pro-vince is a vital area for water conservation and environmental fragile in the upper Yangtze River. Therefore, it is necessary to understand the ecological vulnerability of BLJW for local sustainable development. Based on the sensitivity-recovery-pressure (SRP) model, landscape pattern index and the typical ecosystem type, we constructed the assessment system of ecological vulnerability by taking township as the spatial unit to analyze the spatiotemporal pattern of ecological vulnerability from the township, county, watershed scales in BLJW of Gansu Province in 2002 and 2014 via the auxi-liary regression, entropy weight, synthetic index, and spatial autocorrelation methods. The results showed that from the view of the township scale, the townships of severe or extreme vulnerability were concentrated in the northwestern Tanchang and most of Wudu in 2002 and 2014. The ecological vulnerability in the watershed had changed from moderate vulnerability to light vulnerability at township scale. At the county scale, the change of ecological vulnerability in Zhouqu was relatively stable, while that of Wudu, Wenxian, Tanchang and Diebu were relatively violent from 2002 to 2014. The ecological vulnerability of Wudu, Wenxian and Diebu improved to a certain extent, while that of Tanchang was deteriorating gradually. On watershed scale, the average value of ecological vulnerability index in the watershed were 0.2976 and 0.2904 in 2002 and 2014, respectively, showing a small downward trend, indicating that the ecological vulnerability in the watershed decreased in the past 12 years. The coefficients of variation were 0.3905 and 0.4358, respectively, with an increasing trend, suggesting that the spatial pattern of ecological vulnerability in the watershed developed in an unbalanced way. In 2002, the Moran I of ecological vulnerability index in the watershed was 0.5460, implying that the ecological vulnerability in the watershed was spatially agglomerated. Specifically, the areas of high-high were mainly distributed in the northern and central Wudu, and northwestern Tanchang. In 2014, the Moran I of ecological vulnerability index in the watershed increased to 0.5635, which indicated that the spatial agglomeration was more significant, and the areas of high-high were concentrated in central Wudu and northwestern Tanchang.
    Spatiotemporal changes of landscape pattern using impervious surface in Guangdong-Hong Kong-Macao Greater Bay Area, China.
    FENG Shan-shan, FAN Feng-lei
    2018, 29(9):  2907-2914.  doi:10.13287/j.1001-9332.201809.013
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    Impervious surface is a key indicator for urbanization degree and the quality of urban environment. It is of great ecological significance to study the evolution of urban landscape based on impervious surface. We explored the spatiotemporal changes of impervious surface landscape pattern in Guangdong-Hong Kong-Macao Greater Bay Area from 2006 to 2016 using multi-temporal Landsat images based on landscape pattern index. The results showed that the impervious surface area (ISA) significantly increased in Guangdong-Hong Kong-Macao Greater Bay Area from 12127.69 km2 in 2006 to 20188.87 km2 in 2016, with an annual growth rate of 806.12 km2. High-density ISA was distributed in Guangzhou-Foshan and Shenzhen-Dongguan districts on the east and west of the Pearl River, respectively. In general, patch numbers, patch density, and edge density, as well as shape complexity and its fragmentation kept increasing during the past decade. The landscape pattern tended to be disordered, fragmented, and irregular. Moreover, the difference of impervious surface landscape pattern is obvious between cities. The areas with highest connectivity, stability and regularization were distributed in Hong Kong and Macao, while the landscape pattern in Huizhou and Jiangmen trended to be fragmentized and complex.
    Effect of film mulching and microbial inoculation on maize growth and water use efficiency under drought stress.
    QIU Lang, BI Yin-li, ZHANG Yan-xu, CAI Yun, YU Hai-yang
    2018, 29(9):  2915-2924.  doi:10.13287/j.1001-9332.201809.034
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    To resolve the problem of soil nutrient and water deficiency in arid and semiarid regions of Northwest China, and considering the symbiotic relationship between microbes and crops, we set up two water regimes: drought stress (35% of the soil water holding capacity) and normal water supply (75% of the soil water holding capacity), two film mulching patterns (non-film mulching and film mulching), and four levels of microbial inoculation [single inoculation with AM fungi (AM), single inoculation with phosphate solubilizing bacteria (PSB), co-inoculation of AM fungi with phosphate solubilizing bacteria (AM+PSB) and the control (CK)]. This study aimed to evaluate the effects of microbial inoculation on maize growth, nutrient absorption, and water use efficiency under different treatments of water regime and film mulching. Results showed that drought stress significantly increased the mycorrhizal colonization of inoculated plants, but significantly decreased soil external hyphal length, T-GRSP and EE-GRSP content. Under drought stress, AM inoculation showed the best promoting and mycorrhizal effect on maize growth by increasing biomass and water use efficiency, soil organic carbon content, the absorption and transportation of soil N, P, K, and thus increasing the N, P, K uptake. Under normal water supply, the inoculation effect of AM+PSB was better than that of AM or PSB treatment, especially combined with film mulching. Results from correlation analysis showed that plant biomass, leaf SPAD value, and nutrient uptake of maize aboveground were significantly positively correlated with soil external hyphal length, whereas water use efficiency was significantly negatively correlated with soil external hyphal length.
    Comprehensive assessment of soil fertility characteristics under different long-term conservation tillages of wheat field in Weibei Highland, China.
    WANG Qian, LI Jun, NING Fang, SUN Lei, WEN Peng-fei
    2018, 29(9):  2925-2934.  doi:10.13287/j.1001-9332.201809.030
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    Soil fertility properties described by four physical indices and seven chemical indices in the 10-year long-term experiment of wheat fields in Weibei Highland were used to investigate the cumulative effect of 11 soil indices under six long-term conservation tillage treatments. The principal component analysis was performed to comprehensively evaluate the cumulative effect of soil fertility under different tillage treatments, so as to provide scientific basis for soil sustainable utilization and management in Weibei Highland. The results showed that, compared with continuous conventional tillage (CT/CT), soil bulk density by no-tillage/subsoiling rotational tillage (NT/ST), subsoiling/conventional tillage rotational tillage (ST/CT) and conventional tillage/no-tillage rotational tillage (CT/NT) decreased by 6.6%, 5.9% and 6.6%, respectively, and no significant difference was found between continuous no-tillage (NT/NT) and CT/CT. NT/NT had the highest content of >0.25 mm mechanical stable aggregate, and no-tillage/subsoiling rotational tillage (NT/ST) had the highest content of >0.25 mm water stable aggregate. Compared with CT/CT, the mechanical stable aggregate contents under other five tillage treatments increased by 1.7%-10.1%, soil organic matter increased by 0.6%-11.2%, and the contents of nitrogen, phosphorus, and potassium contents also increased. By principal component analysis, 11 soil indices were divided into two principal components to comprehensively characterize soil quality. The contribution rate of the first principal component was 75.5%, where the major contributors were soil organic matter, water stable aggregate, total nitrogen, total phosphorus, total potassium, alkaline hydrolysis nitrogen, available phosphorus, available potassium, bulk density and soil porosity. The contribution rate of the second principal component was 13.2%, where the major contributor was mechanical stable aggregate. Together, those two principal components accounted for 88.6% of the original variables. The soil fertility performance was in the sequence of NT/ST>ST/CT>CT/NT>NT/NT>ST/ST>CT/CT after gradually accumulating the effects of long-term conservation tillage. NT/ST was the most appropriate tillage patterns for the wheat fields in Weibei Highland, due to the resulting balanced and high-quality soil environment.
    Optimizing fertilization scheme of N, P2O5 and K2O concentration for eggplant under soilless culture.
    MA Sheng, CHEN Zhen, YANG Feng-juan, WANG Xiu-feng, WEI Min, SHI Qing-hua, LI Yan, GONG Biao
    2018, 29(9):  2935-2942.  doi:10.13287/j.1001-9332.201809.029
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    To get optimal nitrogen (N), phosphorus (P2O5) and potassium (K2O) concentrations range for high quality and yield of eggplant with vermiculite as cultivation substrate, three factors and quadratic saturation D-optimal regression (310) were used to establish a ternary quadratic mathematical model with N, P2O5 and K2O concentrations as independent variables and eggplant yield and quality as objective functions. The results showed that yield and quality of eggplants were significantly influenced by N, P2O5 and K2O concentrations. The yield was most influenced by K2O concentration, and followed by N and then P2O5. The quality was also most influenced by K2O concentration, and followed by P2O5 and then N. There were significant interactive effects of N+P2O5, N+K2O and P2O5+K2O on yield, and significant interaction of N+K2O on eggplant quality. Under lower concentrations, the yield and quality of eggplants enhanced with the increasing N, P2O5 and K2O concentrations. When the nutrient concentrations exceeded a threshold, both yield and quality decreased. According to computer simulations, the yield could reach to 3600 g·plant-1 when the fertilization schemes were N 16.0-20.0 mmol·L-1, P2O5 2.2-2.6 mmol·L-1 and K2O 9.9-12.9 mmol·L-1; the fertilization scheme needed to obtain a comprehensive quality score of higher than 90 were N 18.0-21.1 mmol·L-1, P2O5 1.9-2.6 mmol·L-1 and K2O 10.6-13.3 mmol·L-1. In summary, fertilization scheme of high yield (43.2 kg·plot-1) and high quality(comprehensive score of higher than 90) of eggplants were N 18.0-20.0 mmol·L-1, P2O5 2.2-2.6 mmol·L-1, K2O 10.6-12.9 mmol·L-1, with an appropriate N, P2O5 and K2O proportion of 1:0.13:0.62.
    Effect of long-term straw mulching and no-tillage on physical properties of meadow soil in cold region.
    WANG Qiu-ju, ZHANG Jing-tao, GAI Zhi-jia, CAI Li-jun, LIU Jing-qi, ZHAO Gui-fan, DU Jia-xing, JIAO Feng
    2018, 29(9):  2943-2948.  doi:10.13287/j.1001-9332.201809.025
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    The effects of different straw returning technology and farming system on soil physical properties is not clear in Heilongjiang Province, which is located in middle temperature zone with large amount of straw. Here, the effects of straw mulching on soil physical properties in meadow soil under no tillage conditions were studied in field experiments for eight consecutive years (2010-2017). The no straw covering (0%), 30% coverage (30%), 60% coverage (60%) and 100% coverage (100%) were disposed in the experiment. The results showed that straw mulching under no tillage significantly increased soil bulk density by 0.10-0.20 g·cm-3, which increased with the increases of coverage amount. Straw mulching increased soil solid fraction by 2.5%-7.8%. Soil temperature decreased with the increases of coverage amount, and this trend was more apparent on the surface of soil. The temperature reduction in 0-5 cm soil layer was 1.87-2.90 ℃. Soil water content significantly increased with the increases of straw mulching, with an enhancement of 6.4%-10.2%. Straw mulch decreased the total porosity and diameter of >0.05 mm aeration pores, increased the effective pore size of 0.05-0.002 mm, with the magnitude of such effects being positively dependent on coverage amount. There was no significant effect of straw mulching on inactive porosity of soil. Long-term straw mulching increased soil compaction and soil moisture, reduced soil temperature and total soil porosity, and increased soil available porosity in 0-5 cm soil layer.
    Effect of straw belt-mulching on soil temperature and yield of winter wheat in rain-fed semiarid region.
    CHANG Lei, HAN Fan-xiang, CHAI Yu-wei, YANG De-long, YANG Chang-gang, CHENG Hong-bo, HUANG Cai-xia, CHAI Shou-xi
    2018, 29(9):  2949-2958.  doi:10.13287/j.1001-9332.201809.023
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    To evaluate the effects of straw belt-covering on soil temperature and yield of winter wheat in rain-fed semiarid region in Northwest China, five mulching modes, including flat field planting without any mulching (CK), whole plastic film mulching (PM), straw mulching by 30 cm covering belt with an interval of 30 cm planting belt with three-row sowing (SM1), straw mulching by 40 cm covering belt with an interval of 40 cm planting belt with four-row sowing (SM2), and straw mulching by 50 cm covering belt with an interval of 50 cm planting belt with five-row sowing (SM3), were set by two-year fixed-site trails in 2013-2015. The results showed that soil temperature significantly varied among different growth stages and soil layers in all treatments. SM1, SM2 and SM3 significantly decreased soil temperature by 1.0-1.3 ℃, 0.7-0.9 ℃ and 0.7-1.1 ℃ in the 0-25 cm soil layer, respectively. The mulching had double effects with increasing and decreasing soil temperatures. The straw mulching significantly increased soil temperature in the duration of seedling to overwintering stage, but greatly decreased soil temperature in the duration of reviving to mature stage. The temperature-increasing effect of film mulching was stronger than that of straw mulching, which was opposite to the temperature-decreasing effect. Straw mulching significantly reduced in the effective accumulated temperature and the daily temperature variations during the whole growth stages. The effective accumulated temperature under straw mulching decreased by 3.4-33.5 ℃·d, and the soil temperature difference decreased by 0.6-2.0 ℃. During over-wintering stage, the straw mulching showed a higher average soil temperature (0.2-0.3 ℃) and negative accumulated temperature (0.4-17.0 ℃·d) than those under the CK. The straw mulching significantly increased grain yield by 11.9%-19.5%. The variations of spikes per unit area were the main factor responsible for yield difference. The findings indicated that that straw mulching method is suitable for winter wheat production in rain-fed region of Northwest China.
    Effects of elevated CO2 concentration on production and water use efficiency of spring wheat in semi-arid area.
    ZHANG Kai, WANG Run-yuan, LI Qiao-zhen, WANG He-ling, ZHAO Hong, YANG Fu-lin, ZHAO Fu-nian, QI Yue
    2018, 29(9):  2959-2969.  doi:10.13287/j.1001-9332.201809.028
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    In the present study, the response of spring wheat production and water use efficiency (WUE) to the elevated CO2 concentrations was investigated based on the open-top chamber (OTC) experiment platform in Dingxi, a typical semi-arid area. Three different CO2 concentrations (390 μmol·mol-1, 480 μmol·mol-1 and 570 μmol·mol-1) were involved. The results showed that the air temperature above plant canopy increased and the soil temperature at depth of 10 cm decreased by elevated CO2. The increased CO2 concentration substantially enhanced the total and each component biomass. The aboveground dry mass under the increased CO2 concentrations (480 and 570 μmol·mol-1) was increased by 20.6% and 41.5%, respectively, and the total dry mass was increased by 19.3% and 39.6%, respectively. The biomass enhacement was mainly due to the increases of dry mass of stems and leaves, which was strongly related to the material production capacity during the middle growth stage. The root/shoot ratio under the increased CO2 concentrations (480 and 570 μmol·mol-1) was decreased by 7.3% and 11.8%, respectively, indicating that the elevated CO2 affected the dry matter accumulation of aboveground more than that of belowground. The yields of spring wheat under the increased CO2 concentrations (480 and 570 μmol·mol-1) were higher than that of the control by 8.9% and 19.9%, respectively, mainly due to the increase of grains per spike. The long-term effect of elevated CO2 concentration on the photosynthesis of spring wheat was not obvious. The photosynthetic rate significantly increased, the transpiration rate decreased and the evapotranspiration reduced with the increases of CO2 concentration. WUE at the leaf, population, and yield levels increased under elevated CO2 concentration, with the increase range of WUE being the largest at the population level and the lowest at the yield level.
    Effects of short-chain polyphosphate fertilization on inorganic P transformation and mobilization of Fe, Mn and Zn in soils.
    WANG Xue-wei, WANG Chong, CHU Gui-Xin
    2018, 29(9):  2970-2978.  doi:10.13287/j.1001-9332.201809.024
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    Understanding the transformation of P in polyphosphate form in the soil and its effect on P availability is the prerequisite for reasonable polyphosphate fertilizer application. A pot experiment was conducted to explore the effects of polyphosphate fertilizers and MAP on soil available-P, inorganic P transformation in soils, soil micro-nutrient availabilities of Fe, Mn and Zn. Meanwhile, the effects of different P fertilizer on rape P nutrition and PUE in both calcareous and acid soils were investigated. Compared with the MAP treatment, polyphosphate fertilizers significantly increased plant available P concentrations in calcareous soil. Soil water soluble-P and Olsen-P were increased by 19.0% and 25.4%, respectively, and soil resin-P and NaHCO3-P (high labile P) and NaOH-P (medium labile P) increased by 22.8%, 43.3% and 33.8%, respectively. Those results implied that polyphosphate could reduce the fixation of P in calcareous soil. However, there was no significant effect of polyphosphate fertilization on improving P availability and reducing P fixation in acid soil. In comparison with MAP treatment, polyphosphate treatments significantly mobilized micronutrient in soils and increased the uptake of Fe, Mn and Zn by rape plants. In the calcareous soil, the available Fe, Mn, and Zn increased by 2.1%, 16.2% and 20.8%, respectively. In acid soil, the available Fe, Mn, and Zn increased by 6.6%, 11.9% and 9.2%, respectively. In addition, polypho-sphate treatments significantly increased dry mass, P uptake concentrations and P use efficiency (PUE) of rape in calcareous soil, but not in acid soil. In conclusion, polyphosphate fertilizer could significantly increase P availability and micronutrient availability, plant P nutrition and PUE, especially in calcareous soil. Thus, polyphosphate could be used as alternative of P source substituting the orthophosphate-based P fertilizer in calcareous soil.
    Effects of selenium fertilization on selenium availability in rice soil.
    ZHANG Mu, TANG Shuan-hu, ZHONG Song-zhen, LI Ping, FU Hong-ting
    2018, 29(9):  2979-2987.  doi:10.13287/j.1001-9332.201809.022
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    Selenium (Se) is easy to be fixed in acidic rice soil of South China, and thus its availability is low. The aim of this study was to investigate the influence of Se fertilizer on Se availability in rice rhizosphere and non-rhizosphere soils. The results showed that Se application increased yield and rice Se concentration. The water soluble, exchangeable, Fe/Mn oxide-bound, organic matter/sulfide-bound, and residual Se contents of the rhizosphere soil were lower than those of the non-rhizosphere soil. There was no significant difference in the migration coefficient of Se between the rhizosphere and non-rhizosphere soils. Se application had no significant effect on the migration coefficient of Se between roots and leaves but improved its migration coefficient between leaves and grains. The secretion of organic acids was increased by the application of 0.5 mg·kg-1 and decreased by the application of 1.0 and 5.0 mg·kg-1 Se. The secretion of organic acids had no significant effect on the rhizosphere soil pH. The pH of rhizosphere soil was higher than that of the non-rhizosphere soil, while the application of Se decreased the pH of the rhizosphere soil. With the increases of Se application, the intensity of the infrared absorption of clay mineral (kaolinite) in the rhizosphere soil showed an increasing trend. In this study, most of the Se was transformed into forms that were difficult to be absorbed and utilized by rice and difficult to move to rhizosphere soil. The enhancement of soil Se availability following the secretion of organic acids was not due to its effects on soil pH.
    Effects of glyphosate-resistant transgenic soybean on soil rhizospheric bacteria and rhizobia.
    SHEN Bin, HONG Xin, CAO Yue-ping, HAN Cheng, LIU Biao, ZHONG Wen-hui
    2018, 29(9):  2988-2996.  doi:10.13287/j.1001-9332.201809.002
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    Transgenic soybean is the most widely grown genetically modified crop in the world, with herbicide resistance being the major modified trait. Microbial community is one of the most important indicators for soil quality. The effects of glyphosate-resistant transgenic soybean and glyphosate application on rhizospheric bacteria and rhizobia still remained unknown. In this study, with the non-transgenic parent Zhongdou 32 as control (CK), we investigated the effects of the G10-epsps transgenic glyphosate-resistance soybean SHZD32-01 without or with glyphosate application (abbreviated as GR and GR+G, respectively) on rhizospheric bacteria and rhizobia at different growth stages of soybean in field. Compared with CK, GR and GR+G had effects on soil pH, total organic carbon, total nitrogen and ammonium contents at the seedling and mature stages. GR significantly increased the abundance and diversity of soil rhizospheric bacterial community at the podding stage. GR+G significantly increased the abundance of soil rhizospheric bacterial community at the podding stage but decreased its diversity at the seeding and podding stages. GR and GR+G changed the relative abundance of dominant bacteria populations. Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Planctomycetes and Actinobacteria were generally the dominant ones among the three treatments across all growth stages. Furthermore, GR and GR+G changed the relative abundance of rhizobia but did not change that of soybean-nodulating rhizobia, Bradyrhizobium and Sinorhizobium. The relative abundance of rhizobia in GR+G was decreased significantly at the podding stage. The abundance of actinobacteria and rhizobia was mainly affected by soil pH. Glyphosate-resistant transgenic soybean without or with glyphosate application altered soil rhizospheric bacteria and rhizobia at the podding stage, but the effects disappeared along with the growth of soybean.
    Screening genotypes and identifying indicators of different Fagopyrum tataricum varieties with low phosphorus tolerance.
    YANG Chun-ting, ZHANG Yong-qing, MA Xing-xing, CHEN Wei, DONG Lu, ZHANG Chu, LU Zhi-juan
    2018, 29(9):  2997-3007.  doi:10.13287/j.1001-9332.201809.021
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    Soil phosphorus (P) deficiency is one of the main factors that diminish the yield of crops on the Loess Plateau. Fagopyrum tataricum is a dominant cereal plant on the Loess Plateau, whose responses to low-P stress are significantly different and dependent on its genotypes. Therefore, screening genotypes with efficient P utilization is an important approach to increase the yield of F. tataricum and promote the sustainable development of local agriculture. With fourteen F. tataricum genotypes, the agronomic traits, physiology and biochemical characters of F. tataricum at seedling stage under normal (2 mmol·L-1) and low-P treatment (0.2 mmol·L-1) were studied by using sand culture. By examining the characters of selected F. tataricum at seedling stage, the varieties of F. tataricum with low-P tolerance were screened out and their evaluation indices were assessed to provide theoretical basis for the breeding of F. tataricum with high P-efficiency and the infertile soil cultivation on the Loess Plateau. The results showed that under low-P stress, the shoots of all genotypes were more affected than roots, with the decline of shoot aboveground index, average root diameter, root surface area and root volume, whereas the length of main root was elongated. Root activity and soluble protein content were decreased. In contrast, other physiological and biochemical indicators were increased. Moreover, plant total phosphorus content and plant phosphorus accumulation reduced, but phosphorus use efficiency increased. The principal component analysis divided the 22 individual indicators into four mutually independent comprehensive indicators (cumulative contribution rate of 90.1%). Cluster analysis divided 14 kinds of F. tataricum into three categories: Low phosphorus tolerant, intermediate and phosphorus sensitive. In order to investigate the index of low-P tolerance of F. tataricum at seedling stage, the optimal regression equation was established with the comprehensive evaluation value of low-P tolerance (D value) as the dependent variable and the low-P tolerance index of each indicator as the independent variables. Seven indicators of root surface area, root length, plant height, aboveground dry mass, acid phosphatase, phosphorus accumulation and POD activity were examined, which could be used for the rapid identification of low-P tolerance of F. tataricum at seedling stage.
    Effect of thinning and reshaping on the canopy structure and leaf quality at late growth stage in dense apple orchard in Loess Plateau of eastern Gansu, China.
    SUN Wen-tai, NIU Jun-qiang, DONG Tie, LIU Xing-lu, YIN Xiao-ning, MA Ming
    2018, 29(9):  3008-3016.  doi:10.13287/j.1001-9332.201809.026
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    In order to examine the effects of thinning and reshaping on canopy structure, leaf physio-logical property at late growth stage, characteristic of nutrient accumulation and distribution in leaf, and the spatial and temporal distribution of soil moisture, 18 year-old ‘Fuji’ apple trees in dense apple orchards were used to measure the canopy size, types and numbers of branches, leaf area index before and after the thinning and reshaping practices. The results showed that before pruning, the photosynthesis was limited by non-stomatal factors, with a reduction in Fv/Fm, Fv/Fo PIabs by 1.2%, 11.5%, 13.9%, respectively. However, the thinning and reshaping practices reduced leaf area index and canopy coverage, increased light interception up to 79% and improved tree construction. The total number of shoots decreased to 1100400 per hectare, while the individual shoot numbers were increased by 5.0% and the ratio of spur increased up to 73%. Due to the improvement of canopy lighting distribution, the average leaf area, specific leaf quality, hundred leaf mass and chlorophyll content were increased. With the increases of photosynthesis, the accumulation of photosynthate such as starch was increased by 143.5%. There was a close correlation between leaf development and light interception. Our results indicated that tree structure and canopy light interception could be improved by thinning and reshaping the dense trees, which resulted in higher leaf growth, development and photosynthetic capability but less water loss. Thinning and reshaping should be recommended to the renewal of the dense apple orchards in Loess Plateau of eastern Gansu.
    Effect of soil salinity on insecticidal protein expression in flower buds of Bt cotton.
    WANG Yong-hui, CHEN Jian-ping, GAO Jin, ZHANG Xiang, CHEN Yuan, CHEN De-hua
    2018, 29(9):  3017-3023.  doi:10.13287/j.1001-9332.201809.027
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    To clarify the effects of soil salinity on the insect-resistance of flower buds in transgenic Bt cotton of Xinmian 33B (salt-sensitive) and Zhong 07 (salt-tolerant), five levels (0, 0.15%, 0.30%, 0.45% and 0.60%) of soil salinity were set to investigate the impacts of soil salinity on Bt protein content, relative expression of Bt gene, activities of nitrogen metabolism-related enzymes and substances in flower buds during flowering stage. The results showed that Bt protein contents of flower buds decreased with increasing soil salinity. The Bt protein contents of flower buds decreased significantly when the soil salinity level was above 0.30% in both cotton cutivars. Greater reduction of Bt protein content occurred under severe than moderate soil salinity stress. However, the relative expression of Cry1Ac gene increased in flower buds of both cultivars when the stress level increased. Greater decreases of Bt protein content of flower buds was observed in Xinmian 33B compared to Zhong 07 under the same salinity level. The cultivars with greater reduction in Bt protein contents of flower buds also had greater reduction in the soluble protein content, glutamate pyruvate transaminase (GPT) and glutamic oxaloacetic transaminase (GOT) activities, and greater increments in free amino acid contents, protease activities and peptidase activities. Therefore, the decrease of Bt protein content was caused by decreased synthesis and increased decomposition of protein in flower buds of Bt cotton under soil salinity stress.
    Priority conservation pattern of wetlands in the Yellow River basin based on systematic conservation planning.
    GUO Yun, LIANG Chen, LI Xiao-wen
    2018, 29(9):  3024-3032.  doi:10.13287/j.1001-9332.201809.040
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    Yellow River basin is a significant habitat for biodiversity conservation in China. Here, we established a integrated classification system of wetlands based on climate types and geomorphological units, with which as the coarse-filter surrogates of biodiversity elements to complement the fine-filter surrogates of distribution of focal bird species. Then, we applied the theoretical framework of systematic conservation planning (SCP), with those two biodiversity surrogates as protection objects and watershed as planning units. We calculated social and economic costs (including roads, railroads, towns, rural settlements, dams) and set targets of 30% to input Marxan to figure out the optimal set of planning units, which met the protection target with the minimum of social economy cost and land resources. We identified a conservation priority pattern by calculating the irreplaceability of each unit by Marxan. Then, we compared the priority pattern with the existing reserve system to analyze conservation gap in the Yellow River basin. The results showed that most marsh wetlands were concentrated in the upper reaches of the Yellow River. The coverage of reserves in the source area was large. Some rare wetland types in Inner Mongolia, Gansu and Sichuan were separated from the protection system. The main wetland types in the middle reaches of the Yellow River were riverine wetlands, with low protection coverage rate and large conservation gaps. After protection network system being optimized, the protection effect was improved by29.1%-37.6%. The wetland in the lower reaches of the Yellow River was mainly concentrated in the Yellow River Delta area. The protection system was good and the conservation gaps was small. Overall, riverine wetlands in the middle reaches of the Yellow River basin had the highest area proportion of conservation gaps which needed more attention. Based on the priority conservation pattern, our results provided scientific suggestions for the protection planning and management of wetlands in the Yellow River basin, which would lay a foundation for the water ecological protection of the Yellow River basin from the macro scale.
    Genetic structure and diversity of Harmonia axyridis populations in Shaanxi Province, China.
    LI Jing, ZHANG Xiao-fei, XU Ling-ling, LIU Jin, BAI Ming-hao, WANG Zhen-ying
    2018, 29(9):  3033-3042.  doi:10.13287/j.1001-9332.201809.031
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    Harmonia axyridis, one of the most important insect predators, has been widely used in biological control in agriculture. In this study, the mitochondrial COII gene was used as genetic marker to investigate the genetic structure and diversity of H. axyridis geographic populations distributed in Shaanxi Province. Level of genetic differentiation and gene flow among different populations of H. axyridis were analyzed. For all the 529 H. axyridis individuals from 21 populations, 15 haplotypes were observed (named as Hap1-Hap15). Hap1 and Hap2 were dominant haplotypes in all sampled individuals, accounting for 34.4% and 37.6% respectively. The overall haplotype diver-sity was 0.732, and it ranged from 0.652 to 0.786 within population. The average gene flow (Nm) among 21 populations was 10.13, and the overall FST value was 0.024, implying low genetic diffe-rentiation among all populations. Results from neutrality tests suggested that H. axyridis populations followed the neutral evolution model and the population size remained stable. Molecular variance analysis (AMOVA) showed high proportion of total genetic variance attributed to variations within populations. Phylogenetic tree based on Nei’s genetic distance of different geographic populations showed clear divergence between northern, central, and southern Shaanxi groups. Results from Mantel test suggested that the genetic distance was weakly correlated with geographical distance between populations. Geographical pattern of genetic structure and diversity in populations from different regions indicated weak gene flow between northern, central, and southern Shaanxi due to Qinling Mountains barrier and climate difference.
    Coupling analysis between new-type urbanization and ecological environment in Fujian Pro-vince, China.
    LIU Chun-yu, LIU Ying-ying, DING Rao-gan
    2018, 29(9):  3043-3050.  doi:10.13287/j.1001-9332.201809.017
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    Identifying and revealing the coupling relationship between urbanization and ecological environment and its forming mechanism, and then putting forward regulation measures, will benefit urban management in making decisions. We examined the coupling process between new-style urbanization and ecological environment system of Fujian Province through the coupling model and coupling-coordination model, and realized the spatial visualization based on the index system of urbanization and ecological environment, in which the index weight was based on the variation coefficient. The results showed that the variation of coupling degree between new-type urbanization and ecological environment system was relatively stable, ranging from 0.77 to 0.99 during 2000 to 2015. There was no obvious difference among the cities except for the Putian in 2000 and Zhangzhou in 2010 were in the break-in stage. The coupling-coordination degree between new-type urbanization and ecological environment system fluctuated around 0.50 during 2000 to 2015 with significant spatial differentiation and shorter evolution time from east to west. The coupling-coordination types of Fujian Province were dominated by the harmonious development type, accompanied by the types of moderate unadjusted recession, moderate coordinated development, and high coordinated development. There was transformation phenomenon among different types. Xiamen was the only one deve-loped into the high coordinated development type in 2015. The city development was mainly featured by lagged urbanization, with the lagged ecological environment in Xiamen in 2010 and in both Fuzhou and Xiamen in 2015.
    Permissible pollution bearing capacity model of water function zone based on the perspective of municipal wastewater discharge and its application.
    QIN Lin, SONG Xiao-yu, CHAO Zhi-long, FENG Xiang-hua, Xia Lu
    2018, 29(9):  3051-3057.  doi:10.13287/j.1001-9332.201809.003
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    Permissible pollution bearing capacity was an important basis for the prohibiting pollution discharge and assessing responsibility in the regional water function zone. In order to adapt to the current ‘county-based’ water environmental management mode in water function zone, we exami-ned the permissible pollution bearing capacity from the perspective of municipal permissible pollution discharge. A municipal pollution discharge model was established to predict the permissible pollution bearing capacity, which was then applied to Liquan and Jingyang counties in the downstream of Jinghe River. The results showed that the permissible pollution discharge in Liquan and Jingyang counties were closely related to the river discharge, with the permissible pollution discharge in the flood season being higher than that in the dry season. The COD concentration in the water function zone of Liquan County exceeded water quality target from November to next March. Therefore, the pollution discharge in this period of Liquan County should be reduced. The value of the pollution discharge would affect the results for the calculation of permissible pollution bearing capacity. The municipal wastewater discharge model could obtain more reasonable results of permissible pollution bearing capacity by using relatively stable pollution concentration data. Overall, our results could provide the scientific basis for the strict system of water resource management.
    Combined effects of fluoxetine and triclosan on Pseudorasbora parva.
    YAN Liang, MU Lei, CHEN Hong-xing, GUO Zhong-bao, LUO Yong-ju, XIE Ling-tian
    2018, 29(9):  3058-3066.  doi:10.13287/j.1001-9332.201809.038
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    We examined the effects of binary mixture of two different pharmaceutical and personal care products (PPCPs) on aquatic organisms. The topmouth gudgeon Pseudorasbora parva, native to northeast China, was used to study the combined effects of fluoxetine (FLX) and triclosan (TCS) on its different organs. After acute (4 h) and chronic (42 d) treatments, the combined effects of FLX/TCS on phase I and phase II detoxification enzymes, nervous system, digestive system and antioxidant system were evaluated. The results showed that the AChE activity in the brain of P. parva was transiently inhibited, whereas the activity of EROD in the liver was continuously inhi-bited. The activity of α-Glu in the intestine was induced after acute exposure but was inhibited after chronic exposure. Meanwhile, the level of lipid peroxidation in the liver was elevated after chronic exposure. In conclusion, the mixture of fluoxetine and triclosan produced toxic effects on multiple organs of P. parva, which could be alleviated after prolonged exposure, indicating an acclimation. However, the mechanisms of this acclimation needed further study.
    Invertebrate assemblage structure associated with key environmental factors in the Yangtze River Estuary, China.
    REN Qing-qiang, XIAN Wei-wei, ZHANG Yan, LIU Chun-long, LI Wen-long
    2018, 29(9):  3067-3077.  doi:10.13287/j.1001-9332.201809.036
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    Yangtze River Estuary plays a key role in linking the river and ocean ecosystems. Our understanding on its biodiversity and associated ecological processes remains poor, which is especially true for the invertebrate assemblage. Here, we investigated invertebrate assemblage pattern and associated environmental drivers based on four different seasonal comprehensive investigations across this region in 2014. A total of 35 species, belonging to 20 families, 10 orders and three phylums were identified. Crustaceans (19 species) and mollusks (13 species) were the taxa with higher richness. Dominant invertebrate included Palaemon gravieri, Crangon affinis, Ovalipes punctatus, Acetes chinensis, Portunus trituberculatus and Charybdis bimaculata. Total density and biomass was 4518.96 kN·km-2 and 173.09 kg·km-2 respectively, with the highest value in spring and the lowest in autumn. Biodiversity indices peaked in winter and spring and reached the lowest in summer. Invertebrate assemblage structure showed significant seasonal variation, appearing in a significant difference between the near-shore and the off-shore in spring, and between the northern-waters and southern-waters in other seasons. Results from ordination analysis showed that the spatial variation of invertebrate was mainly regulated by temperature and dissolved oxygen, whereas Chla and nutrient factors played key roles in driving the temporal community assemblage in this region.
    Community structure of zooplankton in adjacent area of Changjiang Estuary, China in summer 2016.
    JIANG Qiao-li, XU Yong-jiu, YU Cun-gen, ZHANG Hao-liang, XIAO Yi, TANG Yi-zheng, ZHANG Ya-zhou
    2018, 29(9):  3078-3084.  doi:10.13287/j.1001-9332.201809.004
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    Based on the data of zooplankton samples from 27 stations in the offshore area of Changjiang Estuary in August 2016, we analyzed the community structure and diversity of zooplankton and examined the relationship between zooplankton community structure and environmental factors. A total of 108 species of zooplankton belonging to 12 groups in six phyla, together with 15 types of pelagic larvae and fish eggs were identified. The main groups were copepods, thaliacea, chaetognaths, cladocladus and medusae, with the average abundance being 273.9, 115.0, 67.1, 63.6 and 61.1 ind·m-3. The most dominant group of zooplankton was copepods (48 species), accounting for 44.4% of the total zooplankton abundance. Medusae ranked second with a total of 12 species, accounting for 11.1% of the total zooplankton abundance. Furthermore, the absolute dominant group was copepods, with the highest contribution to the zooplankton community (20.3%). According to the clustering results of environmental factors, the area could be divided into Changjiang diluted water and offshore water mass. The results of analysis of similarities showed that the difference of zooplankton community between the two regions was significant (the average diffe-rence was 4%), and the contribution to the difference was 20.3%, 18.0%, 14.1%, 13.4%, and 11.8% for copepod, thaliacea, cladocera, chaetognaths, and medusae, respectively.
    The breadth and overlap of ecological niche of major fish species in the Minjiang River Estuary, China.
    HE Xiong-bo, LI Jun, SHEN Chen, SHI Yan, FENG Chen, GUO Jun-hong, ZHAO Chun-xu, YAN Yun-rong, KANG Bin
    2018, 29(9):  3085-3092.  doi:10.13287/j.1001-9332.201809.037
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    Based on the seasonal bottom trawl surveys in the Minjiang River Estuary in 2015, the breadth and overlap of ecological niche of major fish species were analyzed. Those fish species were identified based on the index of relative importance (IRI). A total of 137 species belonging to 37 families and 16 orders were collected. Fifteen major fish species were determined by the IRI, including six dominant species Polydactylus sextarius, Harpadon nehereus, Pennahia argentata, Secutor ruconius, Cynoglossus abbreviates, Coilia mystus, and nine important species Collichthys lucidus, Amblychaeturichthys hexanema, Upeneus japonicas, Lagocephalus spadiceus, Pampus argenteus, Larimichthys crocea, Thryssa kammalensis, Takifugu oblongus, Lepturacanthus savala. Seven species whose spatio-temporal niche breadth was higher than 1 in a declining order were C. abbreviates, C. lucidus, S. ruconius, A. hexanema, T. kammalensis, C. mystus, H. nehereus. The ecological niche of major fish species in the Minjiang River Estuary showed obvious seasonal dynamics. The percentage of species pairs with spatio-temporal niche overlap at the meaningful level was as high as 81.9%. Six species pairs reached significant ecological niche overlap, indicating that major fish species had similar distribution at the spatial and temporal scales and the existence of resource utilization competition. The species pairs of U. japonicus-L. savalawas had the highest spatio-temporal niche overlap value, whereas U. japonicus-C. lucidus had the lowest niche overlap value. The spatio-temporal niche overlap of major fish species in the Minjiang River Estuary had substantial seasonal variation.
    Comparison between traditional sequencing and high-throughput sequencing on the dietary analysis of juvenile fish.
    LIN Xian-zhi, HU Si-min, LIU Sheng, HUANG Hui
    2018, 29(9):  3093-3101.  doi:10.13287/j.1001-9332.201809.005
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    Feeding analysis of fish at early growth stages is helpful to understand its food source and functional role. Comprehensively and accurately obtaining the information of food species is critical for this endeavor. The development of high-throughput sequencing (HTS) technology has brought unprecedented opportunities and challenges to dietary analysis of animals. Molecular techniques have been widely used for analyzing diet composition of different animals, among which HTS has been successfully used on marine fish. But the accuracy and suitability of HTS have not been confirmed and compared with traditional Sanger sequencing on the dietary analysis of juvenile fish yet. In this study, a comprehensive comparison was performed between traditional Sanger sequencing and HTS on the diet analysis of Scatophagus argus juveniles, an important commercial fish in South and Southeast Asia. The juvenile fish were collected near a wharf in Daya Bay, China, and analyzed both by traditional Sanger sequencing and HTS methods targeting 18S rDNA gene. Results showed that the diet composition was complicated and dominated by ciliates and bryozoans, indicating an omnivorous feeding of juveniles. Sixty-seven effective sequences were obtained and 21 food species were identified by Sanger sequencing, while 35 food species from 17000 effective sequencings were identified by HTS. The food groups obtained by both techniques were similar. HTS had advantages in dietary coverage due to the large amount of data. HTS detected preys of dinoflagellates and brown algae which were not found in Sanger sequencing. In addition, HTS could provide semi-quantitative information to some extent based on a large amount of data, overcoming the deficiency of Sanger sequencing in quantitative research. Our results suggested that HTS is much more powerful than Sanger sequencing on diet analysis of juvenile fish, which can provide more details and comprehensive information about the feeding of juvenile fish.
    Antioxidant responses of rainbow trout with different ploidies to acute temperature stress.
    SHI Kun-peng, DONG Shuang-lin, ZHOU Yan-gen, GAO Qin-feng, SUN Da-jiang
    2018, 29(9):  3102-3110.  doi:10.13287/j.1001-9332.201809.001
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    Rainbow trout (Oncorhynchus mykiss) is a cold-water fish species with optimal temperature of 12-18 ℃. Temperature stress is a common issue in commercial culture of the Salmonid fish in summer. Both maple trout and steelhead trout are rainbow trout breeding species with good quality. The purpose of this study was to explore the impact of acute temperature stress on antioxidant responses of two kinds of rainbow trout. The juvenile maple trout was diploid, and the juvenile steelhead trout was triploid. The fishes were exposed to four different temperature treatments: 13, 17, 21, and 25 ℃, and hepatic samples were collected at 0, 1, 6, and 12 h. After acute heat stress, the fish were transferred to the tank with optimal temperature (13 ℃) and hepatic samples were collected after 1, 12, 24, and 48 h. The biomarkers, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), lipid peroxidation (LPO), malondialdehyde (MDA), and heat shock protein 70 kDa (HSP70) were measured. Results showed that the activities of SOD, CAT, and GPx in both maple trout and steelhead trout in 17 ℃ treatment had no significant increase after acute temperature stress. The SOD activities of maple trout and steelhead trout in 21 ℃ treatment significantly increased in response to acute temperature stress, but the SOD activity of maple trout returned to normal during the recovery process. The activities of SOD, CAT, and GPx for both species in 25 ℃ treatment were significantly increased after acute temperature stress, which returned to normal for 24 h recovery. The amount of HSP70 produced by maple trout at 17, 21, and 25 ℃ treatments was significantly higher than that at 13 ℃ treatment, while that of steelhead trout was significantly higher for the 21 and 25 ℃ treatments than that at 13 ℃ treatment. A variety of antioxidant parameters were analyzed by integrated biomarker response (IBR) values. Results showed that the antioxidant response of maple trout was significantly higher than that of steelhead trout in 17 ℃ and 21 ℃ treatments, but significantly lower than steelhead trout in 25 ℃ treatment. Such a result indicated that the antioxidant responses of different ploidy rainbow trouts were different under acute stress at different temperatures.
    Spatial distribution of cladoceran assemblages in surface sediments of shallow lakes in Yunnan.
    ZHU Qing-sheng, KONG Ling-yang, CHEN Li, WANG Xiao, WANG Jiao-yuan, KANG Wen-gang, LI Rui, LIANG Hong, CHEN Guang-jie
    2018, 29(9):  3111-3119.  doi:10.13287/j.1001-9332.201809.032
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    Shallow lakes, sensitive to environmental changes due to low environmental carrying capacity, generally experience decreases in ecosystem function and even regime shifts after over-exploitation. Surface sediments of 18 shallow lakes in Yunnan were collected and analyzed to identify the spatial pattern and the influencing factors of cladoceran communities. The results showed that there was significant heterogeneity in the spatial distribution of cladocera in those lakes. For example, the cladoceran community was generally dominated by benthic taxa in alpine lakes, while there was a clear replacement of benthic cladocerans by planktonic ones with increasing nutrient levels across lakes from Southeast Yunnan. Altitude and total phosphorus were the main driving factors, which independently explained 22.0% and 7.7% of the change in cladocera communities, respectively. The altitude gradient and related changes in climate and catchment features were the main factors in structuring cladocerans for shallow lakes of Yunnan, while the anthropogenic impacts on cladoceran distribution was significant via the processes such as catchment development, pollutant input and macrophyte changes. Meanwhile, the interaction between elevation and total phosphorus explained 26.3% of the total variance in cladoceran community shift, indicating that the increase in human activity intensity in lakes at lower altitudes would have stronger impact on cladocerans through anthropogenic nutrient inputs.
    Spatial distributions and environmental control of diatom functional groups in sediments of Haixi Lake, Southwest China.
    WANG Jiao-yuan, CHEN Guang-jie, KANG Wen-gang, HU Kui, CHEN Xiao-lin, WU Fei-hong, ZHU Qing-sheng, FENG Zhong
    2018, 29(9):  3120-3130.  doi:10.13287/j.1001-9332.201809.006
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    Functional group classification based on the morphological, physiological and ecological characteristics of diatoms is advanced in describing the tolerance and sensibility of diatoms to environmental stressors. In this study, we examined the spatial distribution of diatom functional groups in surface sediments of Haixi Lake and explored the relationships between diatom distributions and environmental variables using multivariate analyses. Principal components analysis (PCA) and redundancy analysis (RDA) results showed that water depth and total nitrogen (TN) were the key drivers for the heterogeneous distribution of diatom functional groups. Water depth of ca. 8 m was the threshold depth in influencing diatom functional group structures linking with thermal stratification. These results provided a basis for fossil record interpretation of the short core. Diatom functional groups fluctuated over the last century, in keeping with mean annual temperature, sediment TN, and median grain size. Climate warming, accelerated nutrient enrichment and intensified hydrological changes led to the dominance of functional group D, MP and P. Additionally, climate warming and nutrient enrichment led to increased diatom functional group diversity, while increased water depth (led by damming and reservoir reinforcement) contributed to diversity loss around 1957 and 1990 AD, respectively.
    Ecological carrying capacity of shellfish in the Yellow River estuary and its adjacent waters.
    LIN Qun, WANG Jun, LI Zhong-yi, SHAN Xiu-juan, ZUO Ming, LIU Yan-fen
    2018, 29(9):  3131-3138.  doi:10.13287/j.1001-9332.201809.039
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    Yellow River Estuary and adjacent waters are famous shellfish production areas. Mactra veseriformis, Ruditapes philippinarum, and Meretix meretrix are important species for stocking enhancement. At present, the annual output of shellfish bottom sowing culture has reached 300 thousand tons, with an output value of 1.54 billion RMB. Over stocking of shellfish will cause environmental changes in marine, increase shellfish mortality and endanger ecosystem health. Accordingly, the assessment of the carrying capacity for shellfish based on ecosystem underpins responsible marine fisheries enhancement. In this study, an Ecopath mass-balance model of the Yellow River estuary and adjacent waters ecosystem constructed by Ecopath with Ecosim software was used to analyze the summary statistics parameters of the ecosystem, mixed trophic interactions, and to calculate the ecological carrying capacity of shellfish. The results showed that the ratio of total primary production/total respiration (TPP/TR) was 3.45, that of total primary production/total biomass (TPP/B) was 38.91, with the low Finn cycling index (0.028), high surplus production being 961.24 t·km-2·a-1 and low system connecting index (0.38), indicating that this ecosystem was at an unstable development stage. The increases of shellfish biomass would have positive impacts on Gobiidae, shrimps, crabs, and negative impacts on pelagic fishes, demersal fishes, edible jellyfish, zooplankton. Current biomass of shellfish was 5.5 t·km-2, with the potential enhancement. Based on the Ecopath model, the primary assessment of carrying capacity of shellfish was 18.22 t·km-2 in Yellow River estuary and its adjacent waters. This study provides scientific references for the sustainable development of fisheries resources in the Yellow River estuary.
    Reviews
    Occurrence, degradation and potential ecological risks of triclosan in environment.
    ZHANG Li-na, GONG Xiao-shuang, AN Jing, WEI Shu-he
    2018, 29(9):  3139-3146.  doi:10.13287/j.1001-9332.201809.033
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    Triclosan (TCS) is widely used in many kinds of personal care products due to its good antibacterial properties. However, TCS can enter environment in many ways through the consumption of those personal care products, and result in a series of environmental problem. TCS and its metabolites have their own characteristics such as environmental persistence, bioaccumulation and ecological toxicity, which may bring some potential risks to the ecosystem and human health. We summarized the occurrence and distribution characteristics of TCS in the environment, as well as the possible degradation pathways and products. Furthermore, we systemically introduced the bioavai-lability and the ecotoxicological effects of TCS and its metabolites on the reproduction and genetics of organism, and their potential risks to the ecosystem and human health. Finally, we proposed brief suggestions for further studies of TCS.
    Amino acids in marine particulate matters and sediments and their role as indicators for organic matter degradation.
    ZHOU Bu, YUAN Hua-mao, SONG Jin-ming, LI Xue-gang, LI Ning, DUAN Li-qin, REN Cheng-zhe
    2018, 29(9):  3147-3158.  doi:10.13287/j.1001–9332.201809.035
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    As important components of marine organic matters especially of organic nitrogen, amino acids play an important role in organic matter cycles owing to their lability. The concentration, composition, and distribution of amino acids have been widely used to indicate the degradation state of organic matters in particulates and sediments of marine. Here, the distribution, influencing factors of amino acids and their role in indicating degradation of organic matters were systematically summarized. Gly, Glu, Ala, and Asp were the major components of amino acids in marine particulates and sediments. The contents of amino acids in the particles and sediments showed a decreasing tendency from the coastal waters to the open sea, and adecreased with the water depth. The lower value of %AA-C/TOC, %AA-N/TN and degradation index (DI) based on changes in the composition of amino acids indicated the higher degradation degrees of organic matters. The reactivity index (RI) and ratios of D-AA and L-AA (D/L) based on non-protein amino acids and D-AA were used to indicate the degradation of organic matter according to the bacterial transformation of amino acids, in which RI value closer to 0, higher D/L, and lower ratios of protein amino acids to non-protein amino acids (Asp/β-Ala and Glu/γ-Aba) indicated the higher degree of degradation in organic matters. The migration and transformation of amino acid were mainly affected by dissolved oxygen, nutrient concentrations, sources of organic matter, depositional environments and microbial activities. Further studies should focus on the synergistic effects of particles and sediments, and also the effects and the specific regulatory roles of microorganisms on amino acids.