Table of Content

18 January 2016, Volume 27 Issue 1

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Characteristics of CO₂ flux in an old growth mixed forest in Tianmu Mountain, Zhejiang, China.

NIU Xiao-dong1, JIANG Hong1,2*, ZHANG Jin-meng1, FANG Cheng-yuan1, CHEN Xiao-feng1, SUN Heng1

2016, 27(1):  1-8. 

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The old-growth, multiple ages, multispecies natural forest has played an important role in terrestrial ecosystem dynamics model and the global carbon budget. However, carbon fluxes of old forests in subtropical regions are rarely reported in China. In the present study, the CO₂ flux of an old-growth subtropical evergreen and deciduous broadleaved mixed forest was observed using -eddy- covariance technique in Tianmu Mountain of Zhejiang Province. Based on the data sets which were observed from July 2013 to June 2014, the variations of net ecosystem exchange (NEE), ecosystem respiration (R_e), and gross ecosystem exchange (GEE) were analyzed. The results showed that during the study period, the monthly NEE all had a negative value (acted as a carbon sink) except for December and February (acted as a carbon source). The average monthly NEE was -61.52 g C·m^-2, the monthly carbon sequestration showed a doublepeak curve and the maximum carbon sink was -149.40 g C·m^-2, which occurred in June, while the maximum carbon source was 23.45 g C·m^-2, which occurred in February. The maximum of monthly mean CO₂ flux occurred in June with a value of -0.98 mg·m^-2·s^-1, while the minimum value occurred in December with a value of -0.35 mg·m^-2·s^-1. The NEE at the time point of positive and negative conversion had typical seasonal characteristics. The yearly NEE, R_e, and GEE were -738.18, 931.05 and -1669.23 g C·m^-2, respectively. Compared with other forest ecosystems located at the similar latitude, the carbon fixation of the old-growth forest was larger, likely due to its complicated structure within the canopy and the presence of young-growth regeneration and successional stands. This showed that other than in carbon neutral, old-growth forests of Tianmu Mountain in subtropical China had a strong capability in carbon sequestration.  

Seasonal dynamics of soil organic carbon mineralization for two forest types in Xiaoxing’an Mountains, China.

GAO Fei, LIN Wei, CUI Xiao-yang*

2016, 27(1):  9-16. 

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To investigate the seasonal dynamics of soil organic carbon (SOC) mineralization in Xiaoxing’an Mountain, we incubated soil samples collected from virgin Korean pine forest and broadleaved secondary forest in different seasons in the laboratory and measured the SOC mineralization rate and cumulative SOC mineralization (C_m). We employed simultaneous reaction model to describe C mineralization kinetics and estimated SOC mineralization parameters including soil easily mineralizable C (C₁), potentially mineralizable C (C₀). We also analyzed the relations between C_m, C₁ and their influencing factors. Results showed that the incubated SOC mineralization rate and C_m for 0-5 cm soil layer decreased from early spring to late autumn, while for 5-10 cm soil layer the seasonal variation was not statistically significant for both forest types. The C₁ in 0-5 and 5-10 cm soil layers varied from 42.92-92.18 and 19.23-32.95 mg·kg^-1, respectively, while the C₀ in 0-5 and 5-10 cm soil layers varied from 863.92-3957.15 and 434.15-865.79 mg·kg^-1, respectively. Both C₁ and C₀ decreased from early spring to late autumn. The proportions of C₀ in SOC for two forest types were 0.74%-2.78% and 1.11%-1.84% in 0-5 and 5-10 cm soil layers, respectively, and decreased from early spring to late autumn, indicating that SOC tended to become more stable as a whole from spring to autumn. The C_m and C₀ were significantly positively correlated to in situ soil water content and hot waterextractable carbohydrate content, but were not correlated to in situ soil temperature and cool waterextractable carbohydrate content. We concluded that soil labile organic carbon, soil physical and chemical properties contributed to the seasonal dynamics of SOC mineralization in the forests.

Temperature sensitivity of soil organic carbon mineralization and βglucosidase enzyme kinetics in the northern temperate forests at different altitudes, China.

FAN Jin-juan1, LI Dan-dan1,2, ZHANG Xin-yu2*, HE Nian-peng2, BU Jin-feng2, WANG Qing3, SUN Xiao-min2, WEN Xue-fa2

2016, 27(1):  17-24. 

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Soil samples, which were collected from three typical forests, i.e., Betula ermanii forest, coniferous mixed broadleaved forest, and Pinus koraiensis forest, at different altitudes along the southern slope of Laotuding Mountain of Changbai Mountain range in Liaoning Province of China, were incubated over a temperature gradient in laboratory. Soil organic carbon mineralization rates (C_min), soil β-1,4-glucosidase (β_G) kinetics and their temperature sensitivity (Q₁₀) were measured. The results showed that both altitude and temperature had significant effects on C_min. C_min increased with temperature and was highest in the B. ermanii forest. The temperature sensitivity of C_min〖KG*3〗\[Q₁₀(C_min)\] ranked in order of B. ermanii forest > P. koraiensis forest > coniferous mixed broadleaved forest, but did not differ significantly among the three forests. Both the maximum activity (V_max) and the Michaelis constant (K_m) of the β_G responded positively to temperature for all the forests. The temperature sensitivity of V_max〖KG*3〗\[Q₁₀(V_max)\] ranged from 1.78 to 1.90, and the temperature sensitivity of K_m〖KG*3〗\[Q₁₀(K_m)\] ranged from 1.79 to 2.00. The Q₁₀(V_max)/Q₁₀(K_m) ratios were significantly greater in the B. ermanii soil than in the other two forest soils, suggesting that the β_G kineticsdependent impacts of the global warming or temperature increase on the decomposition of soil organic carbon were temperature sensitive for the forests at the higher altitudes.

Impact of micro-landform on grassland plant community structure and function in the hilly Loess Plateau region, China.

RU Hai-li1,2, ZHANG Hai-dong3, JIAO Feng1,3*, XUE Chao-yu3, GUO Mei-li1,2

2016, 27(1):  25-32. 

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In order to analyze the impact of micro-landform on grassland plant community structure and function, species composition, aboveground and belowground biomass, and annual fine root production at different slope aspects (sunny slope and shady slope) and different slope positions (top, upper, middle and lower) were investigated in the hilly Loess Plateau region. The results showed that grassland communities were mainly composed of plants species belonging to Compositae, Poaceae and Leguminosae. The aboveground and belowground biomass and annual fine root production of community were 164.12 g·m^-2, 1044.87 g·m^-2 and 731.77 g·m^-2·a^-1, respectively. Aboveground biomass, belowground biomass and annual fine root production of community were in the order of shady slope > sunny slope > top slope.
In shady slope, the biomass of community under different positions were in the order of lower > middle > upper > top, but it exhibited different orders in the sunny slope compared with shady slope. Fine root mainly concentrated in the 0-20 cm top soil layer and decreased with soil depth. The average turnover time of root was 0.75 a^-1 and changed with soil layers and micro-landform.

Difference of anti-fracture mechanical characteristics between lateral-root branches and adjacent upper straight roots of four plant species in vigorous growth period.

LIU Peng-fei1, LIU Jing1*, ZHU Hong-hui1, ZHANG Xin2, ZHANG Ge3, LI You-fang1, SU Yu1, WANG Chen-jia1

2016, 27(1):  33-39. 

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Taking four plant species, Caragana korshinskii, Salix psammophila, Hippophae rhamnides and Artemisia sphaerocephala, which were 3-4 years old and in vigorous growth period, as test materials, the antifracture forces of lateral-root branches and adjacent upper straight roots were measured with the self-made fixture and the instrument of TY 8000. The lateralroot branches were vital and the diameters were 1-4 mm. The results showed that the anti-fracture force and antifracture strength of lateralroot branches were lesser than those of the adjacent upper straight roots even though the average diameter of lateralroot branches was greater. The ratios of anti-fracture strength of lateral-root branches to the adjacent upper straight roots were 71.5% for C. korshinskii, 62.9% for S. psammophila, 45.4% for H. rhamnides and 35.4% for A. sphaerocephala. For the four plants, the antifracture force positively correlated with the diameter in a power function, while the antifracture strength negatively correlated with diameter in a power function. The antifracture strengths of lateralroot branches and adjacent upper straight roots for the four species followed the sequence of C. korshinskii (33.66 and 47.06 MPa)>S. psammophila (17.31 and 27.54 MPa)> H. rhamnides (3.97 and 8.75 MPa)> A. sphaerphala (2.18 and 6.15 MPa).

Early selection of drought-resistant  superior families of Reaumuria soongorica based on the analysis of osmoregulation substances and chlorophyll.

GAO Hong-xia1, SU Shi-ping1, LI Yi1*, Жигунов Анатолий Васильевич2

2016, 27(1):  40-48. 

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By using 77 families of 3 year-oldReaumuria soongorica seedlings that grew well without infection of any pests and diseases as experimental material, the contents of soluble protein (SP), soluble sugar (SS), proline (Pro) and chlorophyll (Chl) were measured, and their drought resistance was evaluated with principal component analysis and subordinate function method. The results showed that there were great differences in leaf osmolytes and chlorophyll among the 77 families. The soluble protein content varied from 2.14 to 8.60 mg·g^-1FM, the soluble sugar content was from 6.82 to 21.86 mg·g^-1FM, the proline content was from 118.73 to 1494.30 μg·g^-1FM, the chlorophyll a content was from 321.88 to 897.37 μg·g^-1FM, the chlorophyll b content was from 53.65 to 249.04 μg·g^-1FM, chlorophyll (a+b) was from 387.39 to 1146.40 μg·g^-1FM, and the chlorophyll a/b was from 3.46 to 6.42. All droughtresistant indices had significant difference among R. soongorica families, among which the proline content varied most, followed by the soluble sugar content. Evaluated by using the synthesized multiindex, it was found that 12 families showed good drought resistance, with Zhazigou 1-2 and Zhazigou 1-1 performing the best.

Retrieval of leaf net photosynthetic rate of moso bamboo forests using hyperspectral remote sensing based on wavelet transform.

SUN Shao-bo1,2, DU Hua-qiang1,2*, LI Ping-heng1,2, ZHOU Guo-mo1,2, XU Xiao-jun1,2, GAO Guo-long1,2, LI Xue-jian1,2

2016, 27(1):  49-58. 

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This study focused on retrieval of net photosynthetic rate (P_n) of moso bamboo forest based on analysis of wavelet transform on hyperspectral reflectance data of moso bamboo forest leaf. The result showed that the accuracy of P_n retrieved by the ideal high frequency wavelet vegetation index (VI) was higher than that retrieved by low frequency wavelet VI and spectral VI. Normalized difference vegetation index of wavelet (NDVI_w), simple ratio vegetation index of wavelet (SR_w) and difference vegetation index of wavelet (D_w) constructed by the first layer of high frequency coefficient through wavelet decomposition had the highest relationship with P_n, with the R² of 0.7 and RMSE of 0.33; low frequency wavelet VI had no advantage compared with spectral VI. Significant correlation existed between P_n estimated by multivariate linear model constructed by the ideal wavelet VI and the measured P_n, with the R² of 0.77 and RMSE of 0.29, and the accuracy was significantly higher than that of using the spectral VI. Compared with the fact that sensitive spectral bands of the retrieval through spectral VI were limited in the range of visible light, the wavelength of sensitive bands of wavelet VI ranged more widely from visible to infrared bands. The results illustrated that spectrum of wavelet transform could reflect the P_n of moso bamboo more in detail, and the ove-rall accuracy was significantly improved than that using the original spectral data, which provided a new alternative method for retrieval of P_n of moso bamboo forest using hyper spectral remotely sensed data.

Effects of  rootstocks on the growth and berry quality of Vitis vinifera cv. Cabernet Sauvignon grapevine in Changli zone, Hebei Province, China.

LI Min-min1, YUAN Jun-wei1, LIU Chang-jiang1, HAN Bin1, HUANG Jia-zhen2, GUO Zi-juan1, ZHAO Sheng-jian1*

2016, 27(1):  59-63. 

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Cabernet Sauvignon grafted onto seven rootstocks 188-08, 5BB, SO4, 3309C, 110R, 5C and 101-14M, with the own-rooted vines as control, were investigated to study the effects of different rootstocks on the growth, fruit quality and yield of Cabernet Sauvignon in Changli zone, Hebei Province, China. The results showed that Cabernet Sauvignon grafted on 5BB and 5C significantly increased the trunk diameter, and 5C significantly increased one-year-old shoot diameter. 188-08, 5BB and 5C as rootstock obviously improved berry soluble solid content, in addition 188-08 and 5BB significantly increased berry reducing sugar content. The vines on 101-14M and 3309C significantly decreased berry titratable acid content. The rootstock 5C and 101-14M significantly raised grape skin phenol and anthocyanin contents, and rootstock 101-14M significantly increased tannin content in grape skin. Cabernet Sauvignon grafted onto 3309C, 110R, 5C and 101-14M obviously got higher yield per vine than own-rooted vines. Growing parameter, grape quality index and yield per vine grafted on seven rootstocks and own-rooted vine were synthetically evaluated by fuzzy evaluation method, and the synthetical effects of vine grafted on seven rootstocks were better than own-rooted vine, with the order of scores from high to low as 5C, 101-14M, 3309C, 5BB, 188-08, 110R and SO4 under Changli unique climate and environment conditions.

 

Soil anti-erodibility of abandoned lands during different succession stages of plant community in hilly-gullied region of the Loess Plateau: Take Fangta small watershed as an example.

YAN Fang-chen1, JIAO Ju-ying1,2*, CAO Bin-ting1, YU Wei-jie1, WEI Yan-hong2, KOU Meng2, HU Shu1

2016, 27(1):  64-72. 

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Field survey and laboratory experiment were conducted to study the soil anti-erodibility of abandoned croplands during different vegetation succession stages in hillygullied region of the Loess Plateau, based on the analysis of soil particle composition, size distribution and group characteristics, soil aggregate fractal dimensions and stability. The results showed that in the earlier stages of succession from annual to perennial herbs in abandoned croplands, soil size distribution changed a little bit, the fractal dimension of soil particle increased, soil structure improved, fractal dimension and damage percent of soil aggregate structure decreased, soil stability increased, thus soil antierodibility increased. Therefore, natural restoration of vegetation is of great significance to improve the soil structure, increase soil erosion resistance, reduce soil erosion and promote sustainable development of regional ecological environment.

Spatio-temporal change of sand-fixing function and its driving forces in desertification control ecological function area of  Hunshandake, China.

SHEN Lu1,2, TIAN Mei-rong2*, GAO Ji-xi2, QIAN Jin-ping1

2016, 27(1):  73-82. 

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Soil erosion is an important ecological and environmental problem in Hunshandake Desert, and the sandfixing function determines the degree of ecological security in the entire region. In order to clarify the situation of windbreak and sand fixation in Hunshandake area, and to guide the prevention and treatment of desertification on regional scale, based on the meteorological and remote sensing data, this paper quantitatively analyzed the temporal and spatial pattern of windbreak and sand fixation ability between 2000-2010 by the revised wind erosion equation (RWEQ) model, meanwhile, the driving forces for each county (or banner) in the functional zone were analyzed with the method of principal component analysis. The results showed that there was a fluctuation of the sand fixing capacity in Hunshandake over time, generally rendering a decline trend. The coniferous forest and grassland had strong windbreak and sand fixation capacity in unit area among the various land categories. In terms of  spatial distribution, the windbreak and sand fixation function in western and southeastern region was weak and needed to be strengthened with ecological restoration efforts. Through the study of the social driving forces of each administrative region in the function zone, there were 3 main social driving forces of soil erosion in the administrative functions: the intensity of inputoutput, the level of economic development and the level of agriculturehusbandry development.

Distribution characteristics of soil organic carbon under different forest restoration modes on opencast coal mine dump.

WEN Yue-rong1, DANG Ting-hui1,2*, TANG Jun2, LI Jun-chao1

2016, 27(1):  83-90. 

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The content and storage of soil organic carbon (SOC) were compared in six wood restoration modes and adjacent abandoned land on opencast coal mine dump, and the mechanisms behind the differences and their influencing factors were analyzed. Results showed that the contents of SOC in six wood lands were
significantly higher (23.8%-53.2%) than that of abandoned land (1.92 g·kg^-1) at 0-10 cm soil depth, the index were significantly higher (5.8%-70.4%) at 10-20 cm soil depth than the abandoned land (1.39 g·kg^-1), and then the difference of the contents of SOC in the deep soil (20-100 cm) were not significant. The contents of SOC decreased with increase of soil depth, but the decreasing magnitude of the topsoil (0-20 cm) was higher than that of the deep soil (20-100 cm). Compared with the deep soil, the topsoil  significant higher storage of SOC in different woods, the SOC storage decreased with the soil depth. Along the 0-100 cm soil layer, the storage of SOC in six wood lands higher (18.1%-42.4%) than that of the abandoned land (17.52 t·hm^-2). The SOC storage of Amorpha fruticosa land (24.95 t·hm^-2) was obviously higher than that in the other wood lands. The  SOC storage in the shrub lands was 12.4% higher than that of the arbor woods. There were significantly positive correlations among forest litter, fine root biomass, soil water content and SOC on the dump. Consequently, different plantation restorations significantly improved the SOC level on the dump in 0-100 cm soil, especially the topsoil. But there was still a big gap about SOC level between the wood restoration lands and the original landform. To improve the SOC on opencast coal mine dump, A. fruticosa could be selected as the main wood vegetation.

Effects of different re-vegetation patterns on soil organic carbon and total nitrogen in the windwater erosion crisscross region，  China.

LIU Xue-tong1,2, WEI Yan-chun1,2, YANG Xian-long1,2, HAO Ming-de1,3*, WEI Xiao-rong1,2

2016, 27(1):  91-98. 

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This study was conducted to analyze the responses of soil organic carbon (SOC) and total nitrogen (TN) to three typical revegetation patterns, i.e., grassland, alfalfa land and peashrub land on the Loess Plateau of China, and also to assess the dynamics of SOC and TN with revegetation age. The results showed that all the three revegetation practices increased the concentrations of SOC and TN in the 0-10 cm soil layer, but their effects differed with re-vegetation age. Compared with adjacent croplands, the concentrations of SOC and TN in the 0-10 cm soil layer in grassland did not change within 10 years of succession, but increased after 20 years of succession. In alfalfa land, the concentrations of SOC and TN increased by 51.6%-82.9% and 43.4%-67.0% in the 0-10 cm soil layer, with the increasing rates of stocks of SOC and TN being 0.17-0.46 and 0.015-0.043 t·hm^-2·a^-1, respectively. However, SOC and TN were not affected by re-vegetation age in alfalfa land. The increases of concentrations of SOC and TN remained high in the first 20 years after conversion of cropland to peashrub land, but decreased after 40 years of conversion. In conclusion, the conversion of croplands to peashrub or alfalfa land could be better in contributing to high stocks of SOC and TN than natural succession of grassland. However, their positive effects on the enrichment of SOC and TN may not be sustainable due to the scarcity of soil moisture and high water consumption of these two re-vegetation plants.

Effects of different rotation systems on greenhouse gas (CH₄ and N₂O) emissions in the Taihu Lake region, China.

HU An-yong1,2, SUN Xing1, LIU Qin1*

2016, 27(1):  99-106. 

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We conducted a greenhouse gas emissions study of different rice-based cropping systems in the Taihu Lake region. The results indicated that the seasonal CH₄ emission initially increased, but declined over time. CH₄ emission mainly occurred during the early stages of rice growth and decreased after the paddy soil dried. N₂O emission mainly occurred during the fertilizer application and paddy field drying stages. Compared with N₂O emission, CH₄ emission contributed significantly more to the global warming potential (GWP) during the rice season. The proportion of CH₄ emission to the total greenhouse gas emissions, which this study aimed to reduce, ranged from 94.7%-99.6%. CH₄ emissions and their GWP during the rice season varied significantly under different rotation systems, with the order of wheat-rice rotation>Chinese milk vetch-rice rotation>fallowrice rotation, while the N₂O emissions and their GWP exhibited no significant differences. Compared with no nitrogen fertilization, applying N fertilizer significantly reduced CH₄ emission and GWP of the Chinese milk vetch-rice rotation. However, CH₄ emission and GWP did not vary with N application rates. The rice yield was largest when the N application rate was 240 kg·hm^-2. Taking economic and environmental benefits into account, we found that a N application rate of 240 kg·hm^-2 and a strawreturn application of Chinese milk vetch not only reduced greenhouse gas emissions but also achieved the highest rice grain yield, which was recommended as a suitable cropping system for the Taihu Lake region.

Influences of water-saved and nitrogen-reduced practice on soil microbial and microfauna assemblage in paddy field.

GUI Juan, CHEN Xiao-yun, LIU Man-qiang*, ZHUANG Xi-ping, SUN Zhen, HU Feng

2016, 27(1):  107-116. 

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The resource and environmental problems caused by excessive consumption of water and fertilizer in rice production have recently aroused widespread concern. This study investigated the effects of irrigation modes (conventional irrigation and 25% water-saved irrigation) and different N application rates (conventional high-nitrogen fertilization and 40% nitrogen-reduced fertilization) on microbial and microfauna assemblages at tillering and ripening stages in paddy field. The results showed that compared with conventional irrigation (CF), water-saved irrigation (WS) decreased the soil pH at tillering stage. Soil dissolved organic matter (dissolved organic C and N) and microbial biomass C and N were significantly affected by irrigation, nitrogen fertilizer and their interactions. WS or N-reduced fertilization (LN) decreased the contents of dissolved organic matter; WS increased microbial biomass C but decreased microbial biomass N. Nitrate was significantly higher in WS than CF, while ammonium showed reverse pattern. At tillering stage, the soil microbial biomass from bacteria, fungi, actinomy and protozoa was higher in WS than in CF, but the trend was opposite at ripening stage. There was a significant interation between irrigation and fertilization on soil rotifer numbers and microbialfeeding nematodes. At tillering stage, WS increased the numbers of rotifer and nematode, and also the proportion of bacterial-feeding nematode; LN increased the abundance of rotifer but decreased the abundance of nematode. In summary, soil microbial and microfauna assemblages showed different response to water-saved and nitrogen-reduced agricultural managements, which depended on different crop growth stages, but also the complex interactions of water and nitrogen and between biological groups in food webs.

Relationships of water conservation through mulching in fallow period with wheat nitrogen transportation and crop yield in dryland.

ZHANG Meng1,2, SUN Min1, GAO Zhi-qiang1*, ZHAO Hong-mei1, LI Guang1, REN Ai-xia1, HAO Xing-yu1,YANG Zhen-ping1

2016, 27(1):  117-124. 

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Field experiments were carried out to study the effects of different mulching times (30 or 60 d after previous wheat harvest) and mulching methods (wholemulching, halfmulching and nomulching) on wheat plant N absorption and assimilation after deep plowing in fallow period on dryland. The results showed that mulching improved water storage efficiency in fallow period and soil water storage of 0-300 cm at sowing stage significantly. Mulching in fallow period, especially the wholemulching, increased the N accumulation amount of each growth stage, N translocation amount and rate before anthesis (NABA), and N accumulation amount after anthesis (NAAA) and grain N. Yield, N uptake efficiency (NUPE), N partial factor productivity (NPFP) and N harvest index (NHI) were all significantly increased under mulching, and wholemulching had better effects. Mulching at 30 d after previous wheat harvest significantly increased the soil water storage of 0-300 cm at sowing stage and the water storage efficiency in fallow period compared with mulching at 60 d after previous wheat harvest. Compared with mulching at 60 d after previous wheat harvest, mulching at 30 d increased the N
accumulation amount of each growth stage, the N accumulation amount in leaf and shoot at maturity, the NABA of stem + sheath, leaf and shoot and the yield. The soil water at the depth of 0-300 cm at sowing stage was positively correlated to N mobilization amount before anthesis and N accumulation amount after anthesis. The N mobilization amount of stem + sheath had a remarkable direct effect on its yield with the direct path coefficient  of 0.619. In summary, mulching in fallow period increased the soil moisture at sowing stage to promote N absorption and utilization, increase yield and improve quality, and wholemulching in advance had better effects.

Effects of different fertilization regimes on weed communities in wheat fields under rice-wheat cropping system.

YUAN Fang1, LI Yong2, LI Fen-hua1, SUN Guo-jun1,3*, HAN Min1, ZHANG Hai-yan1, JI Zhong4, WU Chen-yu1

2016, 27(1):  125-132. 

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To reveal the effects of different fertilization regimes on weed communities in wheat fields under a rice-wheat rotation system, a survey was conducted before wheat harvest in 2014 after a 4-year- long-term recurrent fertilization scheme. Weed species types, density, height and diversity index under different fertilization and strawreturning schemes in wheat fields were studied and complemented with a canonical correspondence analysis on weed community distribution and soil nutrient factors. Twenty weed species were recorded among 36 wheat fields belonging to 19 genera and 11 families. Beckmannia syzigachne, Hemistepta lyrata, Malachium aquaticum and Cnidium monnieri were widely distributed throughout the sampled area. Long-term fertilization appeared to reduce weed species richness and density, particularly for broadleaf weeds, but increased weed height. Diversity and evenness indices of weed communities were lower and dominance indices were higher in fields where chemical fertilizers were applied alone or combined with organic fertilizers, especially, where organic-inorganic compound fertilizer was used, in which it readily caused the outbreak of a dominant species and severe damage. Conversely, diversity and evenness indices of weed communities were higher and dominance indices were lower when the straw was returned to the field combined with chemical or organic fertilizers, in which weed community structures were complex and stable with lower weed density. Under these conditions weeds only caused slight reduction of wheat growth.

Flag leaf photosynthetic characteristics, change in chlorophyll fluorescence parameters, and their relationships with yield of winter wheat sowed in spring.

XU Lan1*, GAO Zhi-qang2, AN Wei3, LI Yan-liang3, JIAO Xiong-fei3,WANG Chuang-yun4

2016, 27(1):  133-142. 

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With five good winter wheat cultivars selected from the middle and lower reaches of Yangtze River and Southwest China as test materials, a field experiment in Xinding basin area of Shanxi Province was conducted to study the photosynthetic characteristics, chlorophyll content, and chlorophyll fluorescence parameters of flag leaf at different sowing dates, as well as the correlations between these indices and yield for two years (2013-2014). The results showed that the difference in most fluorescence parameters except chlorophyll content among cultivars was significant. The correlations between these fluorescence parameters and yield were significant. The variation coefficient of chlorophyll (Chl) content was low (0.12-0.17), and that of performance index based on absorption (PI_abs) was high (0.32-0.39), with the partial correlation coefficients of them with grain yield from 2013 to 2014 ranged in 0.70-0.81. Under the early sowing condition, the grain yield positively correlated with PI_abs at flowering and filling stages and chlorophyll content at grain filling stage, but negatively correlated with the relative variable fluorescence at I point (V_i) at grain filling stage. About 81.1%-82.8% of grain yield were determined by the variations of PI_abs, Chl, and V_i. Wheat cultivars had various performances in the treatments with different sowing dates and a consistent trend was observed in the two experimental years. Among these 5 cultivars, Yangmai 13 was suitable for early sowing, with the flag leaf photosynthetic rate (P_n), Chl, most fluorescence parameters, and grain yield showed obviously high levels. In conclusion, under early sowing condition chlorophyll content at grain filling stages, PI_abs at flowering and filling stages, and P_n were important indices for selecting wheat cultivars with high photosynthetic efficiency.

Effects of water-potassium interaction on stalk structure and function of high-yield summer maize.

GUO Yan-qing, ZHU Yu-ling, LIU Kai, PEI Shu-jun, ZHAO Bin, ZHANG Ji-wang*

2016, 27(1):  143-149. 

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The effects of water-potassium interaction on stalk structure and function of high-yield summer maize were studied in the waterproof cultivation pools with Zhengdan 958 (ZD958) as the experimental material. The results showed that the quantity of bleeding sap in stalk was significantly improved by irrigation. Potassium (K) application could reduce the influence of drought stress on the quantity of bleeding sap in stalk to a certain extent. The quantity of bleeding sap in stalks during different growth periods were significantly improved in the treatment of 2250 m³·hm^-2 irrigation amount with K application. The stalk rind penetration strength and stem diameter were significantly improved by waterpotassium interactions. Under the irrigation amount of 2250 m³·hm^-2, the stalk rind penetration strength and stem diameter with K application were respectively increased by 46.0% and 36.4% compared with no K application. Under K application, the stalk rind penetration strength and stem diameter in the irrigation amount 2250 m³·hm^-2 were respectively increased by 30.7% and 8.6% compared with 450 m³·hm^-2. The number, area of vascular bundle and the thickness of thickwalled cell, cortex and rind, were significantly improved by the irrigation amount 2250 m³·hm^-2 with K application. In conclusion, application of 180 kg K₂O·hm^-2 and increasing the irrigation amount properly could increase the lodging resistance and yield of summer maize in this field experiment condition．

Effects of brassinolide on leaf physiological characteristics and differential gene expression profiles of NaClstressed cotton.

SHU Hong-mei, GUO Shu-qiao, GONG Yuan-yong, NI Wan-chao*

2016, 27(1):  150-156. 

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This study analyzed the effects of brassinolide (BL) on Na⁺ accumulation, leaf physiological characteristics and differentially expressed genes (DEGs) of cotton leaves under NaCl stress. The results showed that NaCl stress increased the Na⁺, proline and MDA content in the leaves of Sumian 12 and Sumian 22, and changed the expression level of genes in cotton leaves. The application of BL counteracted the NaCl stress-induced growth inhibition in the two tested cotton cultivars. It reduced the accumulation of Na⁺, enhanced proline content, and resulted in a decrease in the MDA content of NaCl-stressed leaves, and the influence of BL on salt-stressed Sumian 12 plants was more ronounced than that on Sumian 22. The digital gene expression analysis in Sumian 12 indicated that BL application significantly influenced the gene expression in NaClstressed cotton leaves, the gene expression pattern as a result of the root applied BL on NaCl-stressed cotton treatment (BL+NaCl) was similar to the normal cotton plants (CK). Our results indicated that brassinolide alleviated NaCl stress on cotton through improving leaf physiological characteristics and gene expression, and resulted in an increase in biomass of NaCl-stressed cotton.

Effects of nitrogen application rates on nitrogen uptake and utilization of direct-seeded cotton after wheat harvest.

ZHANG Guo-wei, YANG Chang-qin, NI Wan-chao, LIU Rui-xian*

2016, 27(1):  157-164. 

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An  experiment was carried out to study the effects of different nitrogen application rates (0, 60, 120, 150, 180 and 240 kg N·hm^-2) on the nitrogen uptake, utilization and distribution of short season cotton cultivar (CCRI50) which was directly seeded after wheat harvest. Results showed that nitrogen application increased the nitrogen uptake of cotton at different growth stages, with the highest increment at the peak floweringboll opening stage. Nitrogen application changed the percentages of nitrogen uptake among different growth stages. The percentages of nitrogen uptake decreased from seedling to peak flowering stage, but increased from peak flowering to boll maturing stage. In addition, nitrogen application reduced the decreasing speed of nitrogen concentration in middle and upper fruiting branches at later growth stages. Direct-seeded cotton had nitrogen and biomass accumulation in the lower and middle reproductive branches. With the nitrogen application of 150-180 kg·hm^-2, the lint yield, NARE (nitrogen apparent recovery efficiency) and the economic coefficient of biomass and nitrogen were relatively higher, and the eigenvalues of dynamic model of nitrogen content and nitrogen accumulation were relatively coordinate. Excessively high nitrogen application (over 180 kg N·hm^-2)  decreased biomass and nitrogen amount of reproductive organ in lower and middle branches, narrow rise of yield, and lower nitrogen use efficiency. However, excessively low nitrogen application (lower than 150 kg N·hm^-2) also resulted in lower economic coefficient of biomass and nitrogen and yield. These results suggested the optimum nitrogen application rate 150-180 kg N·hm^-2 for direct-seeded cotton after wheat harvest in lower reaches of Yangtze River.

Diagnosis method of cotton water status based on infrared thermal imaging.

WU Xiao-lei1,2, ZHANG Ji-yang1,3*, LIU Hao1,3, QIANG Xiao-man1,3, NING Hui-feng1,3, CHEN Xin-guo1,2, GONG Xue-wen1,2

2016, 27(1):  165-172. 

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Canopy temperature is one of promising signals for evaluating crop water status. The infrared thermal imager can provide realtime temperature distributions over larger areas with high spatial resolution. The main factors (the observation orientation, angle and distance) controlling the accuracy of measuring canopy temperature with the infrared thermal imaging were investigated in a cotton field. Moreover, the correlation relationships between the crop water stress index (CWSI), which was observed using different methods, and soil water content (SWC), leaf water potential (LWP), and stomatal conductance (g_s) of cotton in different water treatments were analyzed. Results indicated that the CWSI, which was measured in the opposite direction of the sun with the observation angle of 45°, was in good correlation with LWP, g_s and SWC, indicating it was a suitable observing method of canopy temperature. The canopy temperature gradually decreased with the increasing observation distance, so the calibration was necessary for longdistance measurement. By analyzing the relationship between the temperature at the dry/wet reference surface and the canopy temperature, we developed a suitable and simplified model of CWSI for cotton in the North China Plain.

Effects of cotton stalk biochar on microbial community structure and function of continuous cropping cotton rhizosphere soil in Xinjiang, China.

GU Mei-ying1, TANG Guang-mu2, LIU Hong-liang3, LI Zhi-qiang3, LIU Xiao-wei3, XU Wan-li2*

2016, 27(1):  173-181. 

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In this study, field trials were conducted to examine the effects of cotton stalk biochar on microbial population, function and structural diversity of microorganisms in rhizosphere soil of continuous cotton cropping field in Xinjiang by plate count, Biolog and DGGE methods. The experiment was a factorial design with four treatments: 1) normal fertilization with cotton stalk removed (NPK); 2) normal fertilization with cotton stalk powdered and returned to field (NPKS); 3) normal fertilization plus cotton stalk biochar at 22.50 t·hm^-2(NPKB-1); and 4) normal fertilization plus cotton stalk biochar at 45.00 t·hm^-2(NPKB-2). The results showed that cotton stalk biochar application obviously increased the numbers of bacteria and actinomycetes in the rhizospheric soil.  Compared with NPK treatment, the number of fungi was significantly increased in the NPKB-1 treatment, but not in the NPKB-2 treatment. However, the number of fungi was generally lower in the biochar amended (NPKB-1, NPKB-2) than in the cotton stalk applied plots (NPKS). Application of cotton stalk biochar increased values of AWCD, and significantly improved microbial richness index, suggesting that the microbial ability of utilizing carbohydrates, amino acids and carboxylic acids, especially phenolic acids was enhanced. The number of DGGE bands of NPKB-2 treatment was the greatest, with some species of Gemmatimonadetes, Acidobacteria, Proteobacteria and Actinobacteria being enriched. UPGMC cluster analysis pointed out that bacterial communities in the rhizospheric soil of NPKB-2 treatment were different from those in the NPK, NPKS and NPKB-1 treatments, which belonged to the same cluster. These results indicated that application of cotton stalk biochar could significantly increase microbial diversity and change soil bacterial community structure in the cotton rhizosphere soil, thus improving the health of soil ecosystem.

Effects of different tillage methods on photosynthetic characteristics, dry matter production and economic benefit of double cropping soybean.

TANG Jiang-hua, SU Li-li, LI Ya-jie, XU Wen-xiu*, PENG Jiang-long

2016, 27(1):  182-190. 

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In order to explore suitable mode of high yield cultivation of double cropping soybean after wheat under drip irrigation in northern Xinjiang, field trials were set in 2013-2014 to investigate physiological indices and agronomic traits of double cropping soybean under different tillage methods under drip irrigation. The results showed that leaf area index (LAI), chlorophyll content (SPAD), leaf net photosynthetic rate (P_n), transpiration rate (T_r) and stomatal conductance (g_s) during the determination period under different tillage methods were in the order of tillage plus film covering (TP)> tillage (T)> rotary tillage (RT) > notillage (NT), and the concentration of intercellular CO₂(C_i) was the opposite. LAI, SPAD, P_n, T_r and g_s of TP were higher than that with NT by 55.0%, 9.1%, 41.8%, 37.5% and 56.4%, respectively, and C_i was decreased by 22.1%. TP enhanced the photosynthetic efficiency of soybean and improved the ability of CO2 assimilation, consequently leading to the increase of soybean yield under TP compared to NT. The plant dry matter accumulation of TP treatment was improved greatly, with the pod number and seeds number per plant, 100-seed mass and yield of quadric sowing soybean being increased by 50.3%, 48.1%, 11.8% and 20.8% compared with that under  NT, and the differences were significant. Therefore, the plastic film mulching combined with tillage under drip irrigation technology was suitable for double cropping soybean after wheat in northern Xinjiang under this experimental condition.

Comparison of precision in retrieving soybean leaf area index based on multi-source remote sensing data.

GAO Lin1,2,3, LI Chang-chun1, WANG Bao-shan1, YANG Gui-jun2,3, WANG Lei1,2,3, FU Kui1

2016, 27(1):  191-200. 

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With the innovation of remote sensing technology, remote sensing data sources are more and more abundant. The main aim of this study was to analyze retrieval accuracy of soybean leaf area index (LAI) based on multi-source remote sensing data including ground hyperspectral, unmanned aerial vehicle (UAV) multispectral and the Gaofen1 (GF-1) WFV data. Ratio vegetation index (RVI), normalized difference vegetation index (NDVI), soiladjusted vegetation index (SAVI), difference vegetation index
(DVI), and triangle vegetation index (TVI) were used to establish LAI retrieval models, respectively. The models with the highest calibration accuracy were used in the validation. The capability of these three kinds of remote sensing data for LAI retrieval was assessed according to the estimation accuracy of models. The experimental results showed that the models based on the ground hyperspectral and UAV multispectral data got better estimation accuracy (R² was more than 0.69 and RMSE was less than 0.4 at 0.01 significance level), compared with the model based on WFV data. The RVI logarithmic model based on ground hyperspectral data was little superior to the NDVI linear model based on UAV multispectral data (The difference in E_A, R² and RMSE were 0.3%, 0.04 and 0.006, respectively). The models based on WFV data got the lowest estimation accuracy with R² less than 0.30 and RMSE more than 0.70. The effects of sensor spectral response characteristics, sensor geometric location and spatial resolution on the soybean LAI retrieval were discussed. The results demonstrated that ground hyperspectral data were advantageous but not prominent over traditional multispectral data in soybean LAI retrieval. WFV imagery with 16 m spatial resolution could not meet the requirements of crop growth monitoring at field scale. Under the condition of ensuring the high precision in retrieving soybean LAI and working efficiently, the approach to acquiring agricultural information by UAV remote sensing could yet be regarded as an optimal plan. Therefore, in the case of more and more available remote sensing information sources, agricultural UAV remote sensing could become an important information resource for guiding fieldscale crop management and provide more scientific and accurate information for precision agriculture research.

Physiological responses of sugar beet (Beta vulgaris) to drought stress during vegetative development period under drip irrigation.

LI Yang-yang1, GENG Qing-yun2, FEI Cong1, FAN Hua1*

2016, 27(1):  201-206. 

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Sugar beet (Beta vulgaris cv. Beta 356) was subjected to drought stress during vegetative development by maintaining the soil water content in the 0-40 cm soil depth at 70%, 50% or 30% of field capacity to study the physiological traits of the leaves. Results showed that the compensation index was the highest in the 50% field capacity treatment. Malonaldehyde (MDA) content, relative conductivity, catalase (CAT) activity, and soluble sugar content began to increase 24 h after rehydration. Proline content began to increase 48 h after rehydration. In contrast, no compensation effect was observed in peroxidase (POD) activity after rehydration. Among the active oxygen-scavenging  enzymes, CAT was most sensitive to drought stress. Supplemental irrigation should be carried out promptly when the soil water content dropped to 50% of field capacity during vegetative development. Rehydration could promote self-repair functions in leaves, thus reducing the effects of drought on sugar beet yield and sugar content.

Temporal and spatial variability of livestock and poultry productions and manure nutrients in Shanxi Province, China.

ZHANG Jian-jie1,2, GUO Cai-xia1,2, QIN Wei3, ZHANG Qiang1,2*

2016, 27(1):  207-214. 

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China’s livestock and poultry productions have changed significantly in the last three decades, from mainly traditional and smallscale systems in early 1980s towards more intensive and industrialized ones in recent years, due to the booming economy and the changes in people’ diet. There is an urgent need to increase the understanding of the changes in the livestock and poultry productions and the impact of manure recycle on the environment. Here, we reported on a systematic and quantitative analysis on the temporal and spatial variability of livestock and poultry productions and manure nutrients in Shanxi Province, China, using a large database and a coupled food chain nutrient flow model (NUFER) with GIS. In the period of 1978 to 2012, total animal manure production increased from 1.61×10⁷ t to 2.75×10⁷ t by 171%. The manure N increased from 7.74×10⁴ t to 17.32×10⁴ t, and the manure P from 1.09×10⁴ t to 3.39×10⁴ t. Besides the huge increase in total animal manure production, the distribution of animal manure was much uneven among regions, with high amounts of manure N and P per unit land in the north, middle and southeastern regions and low values in the northcentral and southwestern regions, based on the results of 2012. The uneven distribution of manure was the combined effect of regional specializations in livestock and poultry productions and related policies. Our findings suggested that optimizing the structure of livestock and poultry productions and enhancing interregional collaborations on nutrient management could be two effective measures for reducing pollution and environmental risks, while achieving efficient and sustainable use of manure nutrient in the long term.

Calculation on ecological security baseline based on the ecosystem services value and the food security.

HE Ling1*, JIA Qi-jian2, LI Chao3, XU Hao1,4

2016, 27(1):  215-224. 

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The rapid development of coastal economy in Hebei Province caused rapid transition of coastal land use structure, which has threatened land ecological security. Therefore, calculating ecosystem service value of land use and exploring ecological security baseline can provide the basis for regional ecological protection and rehabilitation. Taking Huanghua, a city in the southeast of Hebei Province, as an example, this study explored the joint point, joint path and joint method between ecological security and food security, and then calculated the ecological security baseline of Huanghua City based on the ecosystem service value and the food safety standard. The results showed that ecosystem service value of per unit area from maximum to minimum were in this order: wetland, water, garden, cultivated land, meadow, other land, salt pans, saline and alkaline land, constructive land. The order of contribution rates of each ecological function value from high to low was nutrient recycling, water conservation, entertainment and culture, material production, biodiversity maintenance, gas regulation, climate regulation and environmental purification. The security baseline of grain production was 0.21 kg·^-2, the security baseline of grain output value was 0.41 yuan·m^-2, the baseline of ecosystem service value was 21.58 yuan·m^-2, and the total of ecosystem service value in the research area was 4.244 billion yuan. In 2081 the ecological security will reach the bottom line and the ecological system, in which human is the subject, will be on the verge of collapse. According to the ecological security status, Huanghua can be divided into 4 zones, i.e., ecological core protection zone, ecological buffer zone, ecological restoration zone and human activity core zone.

Assessment on the ecological suitability in Zhuhai City, Guangdong, China, based on minimum cumulative resistance model.

LI Jian-fei1, LI Lin1， GUO Luo1*

2016, 27(1):  225-232. 

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Urban landscape has the characteristics of spatial heterogeneity. Because the expansion process of urban constructive or ecological land has different resistance values, the land unit stimulates and promotes the expansion of ecological land with different intensity. To compare the effect of promoting and hindering functions in the same land unit, we firstly compared the minimum cumulative resistance value of promoting and hindering functions, and then looked for the balance of two landscape processes under the same standard. According to the ecology principle of minimum limit factor, taking the minimum cumulative resistance analysis method under two expansion processes as the evaluation method of urban land ecological suitability, this research took Zhuhai City as the study area to estimate urban ecological suitability by relative evaluation method with remote sensing image, field survey, and statistics data. With the support of ArcGIS, five types of indicators on landscape types, ecological value, soil erosion sensitivity, sensitivity of geological disasters, and ecological function were selected as input parameters in the minimum cumulative resistance model to compute urban ecological suitability. The results showed that the ecological suitability of the whole Zhuhai City was divided into five levels: constructive expansion prohibited zone (10.1%), constructive expansion restricted zone (32.9%), key construction zone (36.3%), priority development zone (2.3%), and basic cropland (18.4%). Ecological suitability of the central area of Zhuhai City was divided into four levels: constructive expansion prohibited zone (11.6%), constructive expansion restricted zone (25.6%), key construction zone (52.4%), priority development zone (10.4%). Finally, we put forward the sustainable development framework of Zhuhai City according to the research conclusion. On one hand, the government should strictly control the development of the urban center area. On the other hand, the secondary urban center area such as Junchang and Doumen need improve the public infrastructure to relieve the imbalance between eastern and western development in Zhuhai City.

Landscape ecological risk assessment and its spatio-temporal variations in Ebinur Lake region of inland arid area.

ZHANG Yue1,2, ZHANG Fei1,2,3*, ZHOU Mei1,2, LI Xiao-hang1,2, REN Yan1,2, WANG Juan1,2

2016, 27(1):  233-242. 

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The typical region of the Ebinur Lake Basin was chosen as study area. Landsat TM/OLI images for 1998, 2011 and 2013 were obtained. In the study area, landscape was classified into six types, including cropland, woodland, grassland, water body, bare lake bed, salinized land and unutilized land. Landscape indices and ecological risk index were calculated and spatially interpolated for the whole region, which was divided into five different risk zones: extremely low, low, moderate, high and extremely high ecological risk. They were carried out for assessing the spatiotemporal changes in ecological risk for each landscape pattern. The results showed that the regional landscape patterns had experienced significant changes, and the increase in the area of croplands was the main trend in landscape evolution from 1998-2013. The main part of the regional ecosystem faced extremely high risk in 1998, high risk in 2011 and low risk in 2013. The ecological risk level of the study area was significantly decreased in the overall period, and the total area of change from high to low risk was much greater than those from low to high risk.

Effects of land use change on landscape pattern vulnerability in Yinchuan Basin, Northwest China.

REN Zhi-yuan1,2,3*, ZHANG Han1,2,3

2016, 27(1):  243-249. 

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Landscape pattern vulnerability reflects the instability and sensitivity of ecological system to external disturbances and helps to understand the status and trend of ecological environment. This paper used landscape sensitivity index and landscape adaptability index to construct the landscape pattern vulnerability index of Yinchuan Basin, and got the distribution of the landscape pattern vulnerability in 2001 and 2013. Our study explored the effect of the land use degree composite index, the integrated land use dynamic degree, the importance index of land use change and various types of land transfer on landscape pattern vulnerability. Results showed that the land use degree composite index was mainly caused by the increase of the arable land, forest and the construction land. The higher proportion of the arable land or forest, the lower the vulnerability was, and the construction land had the opposite effect. With the increase of integrated land use dynamic degree, the construction land significantly increased the vulnerability, followed by grassland, and the forest significantly decreased the vulnerability, followed by the arable land. As the importance index of land use change increasing, the arable land could significantly decrease the vulnerability, followed by the forest, the grassland had a weaker trend with no obvious pattern, and the construction land significantly increased the vulnerability. When the arable land, forest and the grassland were the main types of land use transfer, the increasing proportion of the construction land increased the vulnerability. When the construction land was the main type of land use transfer, the grassland and forest improved the vulnerability and the arable land had the opposite effect. Changes in the number of land use types influenced the spatial structure of land use to a certain extent, which could offer a reference on using and developing the land resources scientifically. The ternary diagram could reflect the impact of various types of land use change on the landscape vulnerability, which diagram enriched the content of the research on the land use and change.

Efficiency of Trichoderma longibrachiatum T6 in the control of Meloidogyne incognita and its rhizosphere colonization in cucumber.

ZHANG Shu-wu, XU Bing-liang*, XUE Ying-yu, LIANG Qiao-lan, LIU Jia

2016, 27(1):  250-254. 

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Efficiency of different concentrations of Trichoderma longibrachiatum T6 against Meloidogyne incognita and its rhizosphere colonization in cucumber were determined in greenhouse experiments. The results of rhizosphere colonization experiments showed that the number of colonies in cucumber soil and root increased significantly ten weeks after inoculation with the second stage juveniles of M. incognita and different concentrations of T. longibrachiatum T6, and there was significant difference in different concentrations of T. longibrachiatum T6, e.g., the maximum numbers of colonies in soil and root were 7.8×10⁷ and 6.3×10⁵ CFU·mL^-1 respectively after treated with the spore suspension of 1.5×10⁷ CFU·mL^-1. Greenhouse experiments results showed that different concentrations of T. longibrachiatum T6 had significant control effect on different life stages of M. incognita, and the control effect increased with the concentration of T. longibrachiatum T6. T. longibrachiatum T6 significantly increased plant height, root length, aboveground and root fresh mass of cucumber inoculated by M. incognita. T. longibrachiatum T6 could colonize in cucumber rhizosphere, had control effect on M. incognita, and significantly improved the growth of cucumber.

Resistance risk, cross-resistance and biochemical resistance mechanism of Laodelphax striatellus to buprofezin.

MAO Xu-lian, LIU Jin, LI Xu-ke, CHI Jia-jia, LIU Yong-jie*

2016, 27(1):  255-262. 

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In order to investigate the resistance development law and biochemical resistance mechanism of Laodelphax striatellus to buprofezin, spraying
rice seedlings was used to continuously screen resistant strains of L. striatellus and  dipping rice seedlings was applied to determine the toxicity and crossresistance of L. striatellus to insecticides. After 32generation screening with buprofezin, L. striatellus developed 168.49 folds resistance and its reality heritability (h²) was 0.11. If the killing rate was 80%-90%, L. striatellus was expected to develop 10-fold resistance to buprofezin only after 5 to 6 generations breeding. Because the actual reality heritability of field populations was usually lower than that of the resistant strains, the production of field populations increasing with 10-fold resistance would need much longer time. The results of cross-resistance showed that resistant strain had high level cross-resistance with thiamethoxam and imidacloprid, low level cross-resistance with acetamiprid, and no cross-resistance with pymetrozine and chlorpyrifos. The activity of detoxification enzymes of different strains and the syergism of synergist were measured. The results showed that cytochrome P450 monooxygenase played a major role in the resistance of L. striatellus to buprofezin, the esterase played a minor role and the GSH-S-transferase had no effect. Therefore, L. striatellus would have high risk to develop resistance to buprofezin when used in the field and might be delayed by  using pymetrozine and chlorpyrifos.

Influences of biochar and nitrogen fertilizer on soil nematode assemblage of upland red soil.

LU Yan-yan1, WANG Ming-wei1, CHEN Xiao-yun1, LIU Man-qiang1*, CHEN Xiao-min1, CHENG Yan-hong2, HUANG Qian-ru2, HU Feng1

2016, 27(1):  263-274. 

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The use of biochar as soil remediation amendment has received more and more concerns, but little attention has been paid to its effect on soil fauna. Based on the field experiment in an upland red soil, we studied the influences of different application rates of biochar (0, 10, 20, 30, 40 t·hm^-2) and nitrogen fertilizer (60, 90, 120  kg N·hm^-2) on soil basic properties and nematode assemblages during drought and wet periods. Our results showed that the biochar amendment significantly affect soil moisture and pH regardless of drought or wet period. With the increasing of biochar application, soil pH significantly increased, while soil moisture increased first and then decreased. Soil microbial properties (microbial biomass C, microbial biomass N, microbial biomass C/N, basal respiration) were also significantly affected by the application of biochar and N fertilizer. Low doses of biochar could stimulate the microbial activity, while high doses depressed microbial activity. For example, averaged across different N application rates, biochar amendment at less than 30 t·hm^-2 could increase microbial activity in the drought and wet periods. Besides, the effects of biochar also depended on wet or drought period. When the biochar application rate higher than 30 t·hm^-2, the microbial biomass C was significantly higher in the drought period than the control, but no differences were observed in the wet period. On the contrary, microbial biomass N showed a reverse pattern. Dissolved organic matter and mineral N were affected by biochar and N fertilizer significantly in the drought period, however, in the wet period they were only affected by N fertilizer rather than biochar. There was significant interaction between biochar and N fertilizer on soil nematode abundance and nematode trophic composition independent of sampling period. Combined high doses of both biochar and N fertilization promoted soil nematode abundance. Moreover, the biochar amendment increased the proportion of fungivores especially in the drought period, suggesting the biochar was the preferred fungal energy channel in comparison to soil without biochar addition. In summary, complex patterns occurred not only due to the application rate of biochar as well as their interactions with N fertilization but also due to the drought and wet periods. It is, therefore, necessary to consider different ecological factors when evaluating the effects of biochar in future.

Activity patterns and foraging behavior of Apis cerana cerana in the urban gardens in winter.

CHEN Fa-jun1,2, YANG Qing-qing1, LONG Li1, HU Hong-mei1, DUAN Bin1, CHEN Wen-nian1,2*

2016, 27(1):  275-281. 

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Bees and other pollinating insects are the important parts of biodiversity due to their great role in plant reproduction and crop production. To explore the role of city garden in native bees conservation, activity patterns, visiting behaviors and flowering plants with nectar or pollen were recorded in south Sichuan in winter. The results showed that, worker bees (Apis cerana cerana) were active to collect food out hive under suitable weather conditions, the duration of working was long. Peaks of the number of outgoing, entrance and foragers without pollen appeared at 14:00-15:00, and bimodal patterns were observed. While, peak of bees with pollen appeared at 11:00, and a unimodal pattern was observed. Time significantly affected the activity of workers. The workload of honey bees on nectar and pollen collection were different, just less than twenty percent foragers carrying pollen. Temperature and humidity also affected flights of bees to some degree, and bee activities showed similar patterns on different days. However, the activities had diverse characteristics in some time. Though a less number of plants were in flowering, most of them could be utilized by A. cerana cerana, and colonies could effectively get the food resource by behavior adjustment. In addition, visiting activities of bees on the flowers of main garden plants, such as Camellia japonica, showed obvious rhythm. Increasing the flowering plants with nectar and pollen in winter by scientific management of urban gardens would facilitate the creation of suitable habitats for A. cerana cerana and maintaining the wild population.

Effects of starvation on the consumption of energy sources and swimming performance in juvenile Gambusia affinis and Tanichthys albonubes. 

LI Jiang-tao, LIN Xiao-tao*, ZHOU Chen-hui, ZENG Peng, XU Zhong-neng, SUN Jun

2016, 27(1):  282-290. 

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To explore the consumption of energy sources and swimming performance of juvenile Gambusia affinis and Tanichthys albonubes after starvation, contents of glycogen, lipid and protein, burst swimming speeds (U_burst), and critical swimming speeds (U_crit) at different starvation times (0, 10, 20， 30 and 40 days) were evaluated. The results showed that, at 0 day, contents of glycogen and lipid were significantly lower in G. affinis than those in T. albonubes, whereas no significant difference in content of protein between two experimental fish was found. Swimming speeds in G. affinis were significantly lower than those in T. albonubes for all swimming performances. After different starvation scenarios, content of glycogen both in G. affinis and T. albonubes decreased significantly in power function trend with starvation time and were close to zero after starvation for 10 days, whereas the contents of lipid and protein were linearly significantly decreased. The slope of line regression equation between content of lipid and starvation time in G. affinis was significantly lower than that in T. albonubes, whereas there was a significantly higher slope of line equation between content of protein and starvation time in G. affinis. 40 days later, the consumption rate of glycogen both in G. affinis and T. albonubes were significantly higher than that of lipid, while the consumption rate of protein was the least. Consumption amounts of glycogen in all experimental fish were the least, G. affinis consumed more protein than lipid, and T. albonubes consumed more lipid than protein. U_burst and U_crit decreased significantly linearly with starvation time for all experimental fish. Slope of linear equation between U_burst and starvation time was not significantly different between G. affinis and T. albonubes. However, the straight slope between U_crit and starvation time was significantly lower in G. affinis than that in T. albonubes. These findings indicated that there was close relationship between the consumption of energy sources and swimming performance in starvation. Although the store amounts of energy sources and swimming performance were lower in G. affinis than those in T. albonubes, G. affinis mainly used protein during starvation. The result of more stable lipid content and U_crit in G. affinis in starvation  compared with that in T. albonubes indicated that G. affinis had a fair endurance to starvation, which helped them to adapt to the poor nutrition environment in stream habitat.

Diet composition and seasonal variation in feeding habits of Collichthy lucidus in Yangtze  Estuary, China.

WANG Jian-feng1,2, ZHAO Feng1*, SONG Chao1, YANG Gang1, HOU Jun-li1, ZHUANG Ping1,2

2016, 27(1):  291-298. 

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Spiny head croaker (Collichthy lucidus) is an important bottom fish distributing from the East China Sea to the Yellow Sea. In order to investigate the seasonal variation in diet composition and feeding habits, a total of 270 specimens were collected in the Yangtze Estuary from November, 2013 to August, 2014, and analyzed by using the stomach contents analysis method. The importance of different prey items was evaluated by the frequency of occurrence, abundance and mass followed by using these data to calculate the index of relative importance (IRI) and the index of preponderance (Ip) for each taxonomic category. The results showed that the diet of C. lucidus consisted of 30 species belonging to 8 orders, in which shrimps, with 38.5 IRI% and 79.1 Ip values, was the most important prey species. The followings were Mysidacea and Amphipoda. The dominant species in the diet of C. lucidus were Palaemon gravieri, Exopalaemon annandalei, E. carinicauda, Acanthomysis longirostris, A. brevirostris, Synidotea laevidorsalis and Calanus sinicus. The dominant species in the diet varied in different seasons. P. gravieri, E. annandalei and A. brevirostris were dominant species in spring and summer, A. longirostris, A. brevirostris and E. carinicauda in autumn, and P. gravieri, C. sinicus and Pesudeuphausia sinica in winter. There was 10.4% of total samples with empty stomachs, and the highest percent appeared in winter, and the lowest in autumn. The mean stomach fullness index of the whole samples was 0.6%, with the highest found in spring, the lowest in winter, indicating the feeding activity of C. lucidus varied significantly among seasons.

Release and supplement of carbon, nitrogen and phosphorus from jellyfish (Nemopilema nomurai) decomposition in seawater.

QU Chang-feng1,2, SONG Jin-ming1，2*, LI Ning1，2, LI Xue-gang1，2, YUAN Hua-mao1，2, DUAN Li-qin1，2

2016, 27(1):  299-306. 

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Jellyfish bloom has been increasing in Chinese seas and decomposition after jellyfish bloom has great influences on marine ecological environment. We conducted the incubation of Nemopilema nomurai decomposing to evaluate its effect on carbon, nitrogen and phosphorus recycling of water column by simulated experiments. The results showed that the processes of jellyfish decomposing represented a fast release of biogenic elements, and the release of carbon, nitrogen and phosphorus reached the maximum at the beginning of jellyfish decomposing. The release of biogenic elements from jellyfish decomposition was dominated by dissolved matter, which had a much higher level than particulate matter. The highest net release rates of dissolved organic carbon and particulate organic carbon reached (103.77±12.60) and (1.52±0.37) mg·kg^-1·h^-1, respectively. The dissolved nitrogen was dominated by NH₄⁺-N during the whole incubation time, accounting for 69.6%-91.6% of total dissolved nitrogen, whereas the dissolved phosphorus was dominated by dissolved organic phosphorus during the initial stage of decomposition, being 63.9%-86.7% of total dissolved phosphorus and dominated by PO₄^3--P during the late stage of decomposition, being 50.4%-60.2%. On the contrary, the particulate nitrogen was mainly in particulate organic nitrogen, accounting for (88.6±6.9)% of total particulate nitrogen, whereas the particulate phosphorus was mainly in particulate inorganic phosphorus, accounting for (73.9±10.5)% of total particulate phosphorus. In addition, jellyfish decomposition decreased the C/N  and increased the N/P  of water column. These indicated that jellyfish decomposition could result in relative high carbon and nitrogen loads.

Nutrient composition changes in coastal waters of Tangshan Bay, Hebei, China under anthropogenic influence.

LI Zhi-wei1*, CUI Li-tuo2

2016, 27(1):  307-314. 

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Based on the principal component analysis (PCA), data from 25 marine monitoring stations in Tangshan Bay from 1995 to 2012 were collected to study the change of nutrient composition in Tangshan Bay under anthropogenic influence. Results showed that the inorganic nitrogen (DIN) presented an obvious  increase trend in the near 20 years, while the PO₄^3--P and SiO₃^2--Si presented a decrease trend. The average N：P ratio increased from 3.0 in 1995 to 26.0 in 2012, but the average Si：N ratio decreased, indicating the nutrient structure in seawater had substantially changed in the near 20 years. According to the results of PCA, the change of water quality was identified. The analysis extracted the first two principal components (PC). PC1 was associated with DIN, NO₃^--N, NH₄⁺-N, PO₄^3--P and NO₂^--N, which explained 71.5% of the variance. PC2 was characterized by Chl a and SiO₃^2--Si, which explained 21.8% of the variance. It indicated that the water quality of Tangshan bay was closely related to DIN and PO₄^3--P. The two principal component scores revealed the interannual change trend of water quality in the Tangshan Bay under anthropogenic influence, which changed from the N limitation before development and at early stage of development (1995-2005) to the P limitation after development (since 2007). The nutrient composition in Tangshan Bay had changed significantly under anthropogenic influence, therefore, special attention is needed on the the change of nutrients in seawater of Tangshan Bay, especially the increase of inorganic nitrogen content.

Applications of nuclear magnetic resonance in the study of soilplantatmosphere continuum.

YAO Shi-jin1,2, DU Guang-yuan3, MOU Hong-mei1,2, FENG Hao2,4, BAI Jiang-ping5, HE Jian-qiang1,2*

2016, 27(1):  315-326. 

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Status and transport of water in plant body are the main contents of study of soil-plant-atmosphere continuum (SPAC), as well as the base for use and regulation of agricultural water. The process of water transport in plant can be deeply influenced by the environments. Thus, plant needs to adjust its water status to accommodate the environmental change to sustain its own growth and development. Traditional methods for plant water monitoring, such as evaporation flux, pressure chamber, high pressure flow meter, heat pulse, and so on, usually cause damage or even destruction of plant body and disturb the original water status. Thus, they are not able to truly and precisely detect and reflect the real water status of plant. Nuclear magnetic resonance (NMR) is a non-destructive and non-invasive technique which can be used for the measurement of water molecular displacement and transportation. This study aimed to provide an overview of the applications of NMR technique in the study of water distribution and transport in plant roots and stems, as well as the water content in plant cells and tissues. In addition, the existing main problems and possible solutions were analyzed for the applications of NMR in SPAC studies. Several important issues were proposed for the acquisition of more precise and reliable detection signals. It was suggested that the NMR technique would probably make important progress in the relevant fields such as plant water physiology, plantenvironment interactions, and water metabolism. In general, the application of NMR in SPAC system study was still in its infancy in China. The deeper application and expansion of NMR in SPAC study would depend on the development of portable and open NMR equipment that could be easily applied for different plants in field.

Concept and connotation development of niche and its ecological orientation.

PENG Wen-jun, WANG Xiao-ming*

2016, 27(1):  327-334. 

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Proceeding from the niche concept, the article commented the main points of each concept’s connotation basing on a systematic review of development on niche concepts, and divided the process into four phases including germination, standardization, quantification and perfection, with two main academic schools. Questions and challenges during niche’s development and advancement were presented to extract the characteristics and components of niche concept. On these bases, we explored the orientation of niche concept in ecology, and suggested to position it as a macro concept and detail it in specific applications. Further research points and application perspectives were stated in the end.