Table of Content

18 September 2013, Volume 24 Issue 9

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Effects of Chinese fir litter on soil organic carbon decomposition and microbial biomass carbon.

WANG Xiao-feng1,2,3, WANG Si-long1,2, ZHANG Wei-dong1,2

2013, 24(9):  2393-2398. 

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By using ^13C stable isotope tracer technique, this paper studied the effects of Chinese fir litter addition on the soil organic carbon (SOC) decomposition, microbial biomass carbon, and dissolved organic carbon in 0-5 cm and 40-45 cm layers. The decomposition rate of SOC in 40-45 cm layer was significantly lower than that in 0-5 cm layer, but the priming effect induced by the Chinese fir litter addition showed an opposite trend. The Chinese fir litter addition increased the soil total microbial biomass carbon and the microbial biomass carbon derived from native soil significantly, but had less effects on the soil dissolved organic carbon. Turning over the subsoil to the surface of the woodland could accelerate the soil carbon loss in Chinese fir plantation due to the priming effect induced by the litters.

Aboveground biomass of naturalCastanopsis carlesii-Schima superba community in Xiaokeng of Nanling Mountains, South China.

XIE Ting-ting1, LI Gen2, ZHOU Guang-yi1, WU Zhong-min1, ZHAO Hou-ben1, QIU Zhi-jun1, LIANG Rui-you3

2013, 24(9):  2399-2407. 

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By the method of clear cutting, a measurement was made on the aboveground biomass (AGB) of 24-year old natural Castanopsis carlesii-Schima superba community in an 800 m² plot in Xiaokeng of Nanling Mountains, South China. The distribution patterns of the total AGB in different forest layers, tree species, and tree layer organs were investigated, and the AGB regression models were constructed. The results showed that when constructing the AGB regression models, more than 12 samples would be feasible. Based on the measured AGB of 265 felled trees, the AGB models of mixed broadleaved species were AGB=0.128D^2.372 and AGB=242.331(D²H)^0.947. The single tree’s AGB model of C. carlesii, S. superba, and Cunninghamia lanceolata was also established. The total AGB of the forest community was 115.20 t·hm^-2, of which, the AGB of tree layer, understory layer, liana, and litter layer was 111.25, 1.01, 0.36, and 2.58 t·hm^-2, respectively. The AGB of C. carlesii and S. superba took up 39.1% and 28.7% of the tree layer AGB, respectively. The AGB of tree stem and branchleaf occupied 81.0% and 19.0% of the tree layer AGB, respectively.

Effects of elevated CO₂ concentration on physiological characters of three dwarf ornamental bamboo species.

ZHUANG Ming-hao1,2, CHEN Shuang-lin1, LI Ying-chun 1, GUO Zi-wu1, YANG Qing-ping1

2013, 24(9):  2408-2414. 

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By using opentop chambers (OTCs) to simulate the scenes of elevated CO₂ concentrations \[500 μmol·mol^-1(T₁) and 700 μmol·mol^-1(T₂)\], and taking ambient atmospheric CO₂ concentration as the control (CK), this paper studied the effects of elevated CO₂ concentration on the lipid peroxidation and antioxidation enzyme system in Indocalamus decorus, Pleioblastus kongosanensis, and Sasa glabra leaves. After 103 days treatment, the O₂^-_· and MDA contents, relative electron conduction, and soluble sugar content in the three dwarf ornamental bamboo species leaves in T₁ had no obvious change, but the activities of antioxidation enzymes (SOD, POD, CAT, and APX) changed to a certain extent. In T₂, the MDA content and relative electron conduction had no obvious change, but the O₂^-_· and soluble sugar contents and the antioxidation enzymes activities changed obviously. The adaptation capacity of the three bamboo species to elevated CO₂ concentration was in the order of I. decorus > P.kongosanensis > S. glabra.

Net ecosystem CO₂ exchange and its environmental regulation mechanisms in a reed wetland in the Yellow River Delta of China during the growth season.

YANG Li-qiong1,2, HAN Guang-xuan1, YU Jun-bao1, WU Li-xin3, ZHU Min4, XING Qing-hui1,2, WANG Guang-mei1, MAO Pei-li1

2013, 24(9):  2415-2422. 

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By using eddy covariance technique, this paper measured the net ecosystem CO₂ exchange (NEE) in a reed (Phragmites australis) wetland in the Yellow River Delta of China during the growth season of 2011, and investigated the variation patterns of the NEE and related affecting factors. The average diurnal variation of the NEE in different months showed a U-type curve, with the maximum net CO₂ uptake rate and release rate being (0.44±0.03) and (0.16±0.01) mg CO₂·m^-2·s^-1, respectively. The NEE, ecosystem respiration (R_eco), and gross primary productivity (GPP) were all higher in vigorous growth season (from July to September) and lower in early growth season (from May to June) and late growth season (from October to November). Both R_eco and NEE reached their maximum values in August, while GPP reached its peak value in July. During the growth season, the ecosystem CO₂ exchange was mainly dominated by photosynthetic active radiation (PAR), soil temperature (T_s), and soil water content (SWC). There was a rectangular hyperbolic relationship between the daytime NEE and PAR. The nighttime ecosystem respiration (R_eco,n) was exponentially correlated with the T_s at 5 cm depth, and the temperature sensitivity of the ecosystem respiration (Q₁₀) was 2.30. SWC and T_s were the main factors affecting the R_eco,n. During the entire growth season, the reed wetland ecosystem in the Yellow River delta was an obvious carbon sink, with the total net carbon sequestration being 780.95 g CO₂·m^-2.

Relationships between typical vegetations, soil salinity, and groundwater depth in the Yellow River Delta of China.

MA Yu-lei1,2, WANG De2, LIU Jun-min1, WEN Xiao-hu2, GAO Meng2, SHAO Hong-bo2

2013, 24(9):  2423-2430. 

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Soil salinity and groundwater depth are the two important factors affecting the vegetation growth and distribution in the Yellow River Delta. Through field investigation and statistical analysis, this paper studied the relationships between the typical vegetations (Suaeda heteroptera-Tamarix chinensis, Robinia pseudoacacia,  Phragmites australis, and cotton), soil salinity, and groundwater depth in the Delta. In the study area, groundwater depth had significant effects on soil salinity, with the average influence coefficient being 0.327. When the groundwater depth was 0.5-1.5 m, soil salinization was most severe. The vegetation growth in the Delta was poorer, with the NDVI in 78% of the total area being less than 0.4. Groundwater depth and soil salinity had significant effects on the vegetation distribution. Soil salinity had significant effects on the NDVI of R. pseudoacacia, S. heteroptera-T. chinensis, P. australis, and cotton, while groundwater depth had significant effects on the NDVI of S. heteroptera-T. chinensis, but lesser effects on the NDVI of  P. australis, cotton  and R. pseudoacacia.

Effects of fertilization on soil CO₂ flux in Castanea mollissima stand.

ZHANG Jiao-jiao1,2, LI Yong-fu1,2, JIANG Pei-kun1,2, ZHOU Guo-mo1,2, SHEN Zhen-ming3, LIU Juan1,2, WANG Zhan-lei1,2

2013, 24(9):  2431-2439. 

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In June 2011-June 2012, a fertilization experiment was conducted in a typical Castanea mollissima stand in Lin’an of Zhejiang Province, East China to study the effects of inorganic and organic fertilization on the soil CO₂ flux and the relationships between the soil CO₂ flux and environmental factors. Four treatments were installed, i.e., no fertilization (CK), inorganic fertilization (IF), organic fertilization (OF), half organic plus half inorganic fertilization (OIF). The soil CO₂ emission rate was determined by the method of static closed chamber/GC technique, and the soil temperature, soil moisture content, and soil watersoluble organic carbon (WSOC) concentration were determined by routine methods. The soil CO₂ emission exhibited a strong seasonal pattern, with the highest rate in July or August and the lowest rate in February. The annual accumulative soil CO₂ emission in CK was 27.7 t CO₂·hm^-2·a^-1, and that in treatments IF, OF, and OIF was 29.5%, 47.0%, and 50.7% higher than the CK, respectively. The soil WSOC concentration in treatment IF (105.1 mg kg^-1) was significantly higher than that in CK (76.6 mg·kg^-1), but was obviously lower than that in treatments OF (133.0 mg·kg^-1) and OIF (121.2 mg·kg^-1). The temperature sensitivity of respiration (Q₁₀) in treatments CK, IF, OF, and OIF was 1.47, 1.75, 1.49, and 1.57, respectively. The soil CO₂ emission rate had significant positive correlations with the soil temperature at the depth of 5 cm and the soil WSOC concentration, but no significant correlation with soil moisture content. The increase of the soil WSOC concentration caused by fertilization was probably one of the reasons for the increase of soil CO₂ emission from the C. mollissima stand.

Natural regeneration of young Excentrodendron hsienmu in karst mountainous region in Southwest Guangxi,China.

OU Zhi-yang1,2, SU Zhi-yao2, PENG Yu-hua1, HE Qin-fei1, HUANG Xiao-rong1

2013, 24(9):  2440-2446. 

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A field survey was conducted in the karst mountainous region in Pingguo County of Southwest Guangxi, China to explore the structural characteristics, spatial distribution pattern, and growth dynamics of young Excentrodendron hsienmu as well as the main environmental factors affecting the natural regeneration of the E. hsienmu population. In the study area, the population structure of the young E. hsienmu was stable, and exhibited a clumped spatial pattern for the seedlings and seedling sprouts. The ground diameter growth and height growth of the young E. hsienmu presented the same variation trend, i.e., the ground diameter increased with increasing height. The ground diameter growth and height growth of the E. hsienmu seedlings were limited by population density, i.e., decreased with increasing population density. The correlation analysis showed that the trees more than 2.5 m in height and the shrubs were the major stand factors affecting the natural regeneration of young E. hsienmu, while the herbs had no significant correlation with the regeneration. The percentage of covered rock also had no significant effects on the regeneration. KruskalWallis ANOVA showed that there existed significant differences in the height and ground diameter of young E. hsienmu at different slope degrees and slope positions. The population density, height, and ground diameter had significant differences across slope aspects. The natural regeneration of young E. hsienmu was comprehensively affected by the species biological characteristics, intraspecific competition, interspecific competition, heterogeneous habitat, and anthropogenic disturbances.

Primary branch size of Pinus koraiensis plantation: A prediction based on linear mixed effect model.

DONG Ling-bo, LIU Zhao-gang, LI Feng-ri, JIANG Li-chun

2013, 24(9):  2447-2456. 

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By using the branch analysis data of 955 standard branches from 60 sampled trees in 12 sampling plots of Pinus koraiensis plantation in Mengjiagang Forest Farm in Heilongjiang Province of Northeast China, and based on the linear mixed-effect model theory and methods, the models for predicting branch variables, including primary branch diameter, length, and angle, were developed. Considering tree effect, the MIXED module of SAS software was used to fit the prediction models. The results indicated that the fitting precision of the models could be improved by choosing appropriate randomeffect parameters and variance-covariance structure. Then, the correlation structures including complex symmetry structure (CS), first-order autoregressive structure \[AR(1)\], and firstorder autoregressive and moving average structure \[ARMA(1,1)\] were added to the optimal branch size mixed-effect model. The AR(1) improved the fitting precision of branch diameter and length mixed-effect model significantly, but all the three structures didn’t improve the precision of branch angle mixedeffect model. In order to describe the heteroscedasticity during building mixed-effect model, the CF₁ and CF₂ functions were added to the branch mixed-effect-model. CF₁ function improved the fitting effect of branch angle mixed model significantly, whereas CF₂ function improved the fitting effect of branch diameter and length mixed model significantly. Model validation confirmed that the mixedeffect model could improve the precision of prediction, as compare to the traditional regression model for the branch size prediction of Pinus koraiensis plantation.

Impacts of human disturbance on the species composition of higher plants in the wetlands around Dianchi Lake, Yunnan Province of Southwest China.

XIANG Xi-xi, WU Zhao-lu, LUO Kang, DING Hong-bo, ZHANG Hai-yan

2013, 24(9):  2457-2463. 

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Introducing higher plants to build semi-natural wetland ecosystem is one of the key approaches to restore the wetlands and lakes that suffered from serious pollution and destruction. Based on the investigation data from 128 quadrats at 26 sampling sites in the wetlands around Dianchi Lake in December 2011-October 2012, and in combining with the references published in the 1960s, this paper discussed the impacts of human activities on the species composition of higher plants in the wetlands around the Lake. In 2012, there were 299 species of 88 families in the wetlands, of which, 181 species were native species, and 118 species were alien ones (including 32 invasive species). Of the 42 species of hydrophytes in the total species, 13 species were alien ones (including 2 invasive species). In comparing with the species data recorded in the 1960s, 232 plants were newly recorded and 43 species disappeared in 2012. Aquatic plants changed obviously. The decreased species were 2 submerged plants, 2 floating plants, and 5 floating leaved plants, and the increased species were 8 emergent plants. Fourteen community types were identified by cluster analysis, of which, the main communities were those dominated by alien species including Pistia stratiotes and Alternanthera philoxeroides. As compared with the data in the 1960s, the plant communities dominated by native species such as Ottelia acuminate and Vallisneria natans were not found presently. Therefore, in the practice of introducing higher plants to restore the degraded wetlands and lakes, it would be necessary to scientifically and appropriately select and blend plant species to avoid the wetland degradation by human activities.

Variation characteristics of soil microbial activities in the  Tarim Desert Highway shelter forests, Xinjiang of Northwast China.

JIN Zheng-zhong, LEI Jia-qiang, LI Sheng-yu, XU Xin-wen

2013, 24(9):  2464-2470. 

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By the methods of Biolog, fumigation extraction, and colorimetric titration, this paper determined the soil carbon sources metabolic intensities, microbial biomass, and enzyme activities in the Tarim Desert Highway shelterforests with different plantation times, and analyzed the variation characteristics of soil microbial activities in these shelter forests. With the increasing planting years of the shelter forests, the soil microbial metabolic activities (AWCD) and microbial diversity indices enhanced obviously, but the AWCD values in different soil layers had no significant differences. The soil catalase activity among the forests had no significant difference, but the soil cellulase and sucrase activities varied significantly. The soil microbial biomass carbon and nitrogen increased with the increasing planting years of the shelter forests, having a significant difference among the forests, but the microbial biomass phosphorus had no significant difference. The AWCD values had significant correlations with soil available nutrient contents, but less correlations with soil bulk density and moisture content. It was suggested that under the present management patterns and climate conditions, the soil metabolic activities in the Tarim Desert Highway shelter forests would be improved continuously with the increasing planting years of the forests.

Characteristics of soil microbial populations in depressions between karst hills under different land use patterns.

SONG Min1,2,3, ZOU Dong-sheng2, DU Hu1,3, PENG Wan-xia1,3, ZENG Fu-ping1,3, TAN Qiu-jin1,3,4, FAN Fu-jing1,3,5

2013, 24(9):  2471-2478. 

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Based on the investigation and analysis of six soil microbial indices, eight soil conventional nutrient indices, six soil mineral nutrient indices, and 15 vegetation indices in the farmland, grassland, scrub, forest plantation, secondary forest, and primary forest in the depressions between karst hills, this paper analyzed the main soil microbial populations, soil microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP) and their fractal characteristics, and the relationships of the soil microbes with vegetation, soil nutrients, and soil mineral components under different land use patterns. The soil microbial populations differed in their quantity and composition under different land use patterns. Primary forest and farmland had the highest quantity of soil microbial populations, while forest plantation had the lowest one. The three forests had a higher proportion of soil bacteria, the farmland, grassland, and scrub had a higher proportion of actinomycetes, and all the six land use patterns had a low proportion of soil fungi. Under the six land use patterns, the soil MBC, MBN, and MBP were all high, with the maximum in primary forest. There was a good fractal relationship between the soil MBC and microbial populations, but no fractal relationships between the soil MBN and MBP and the microbial populations. Significant relationships were observed between the soil microbes and the vegetation, soil nutrients, and soil mineral components, and the soil MBC had the closest relationships with the Shannon index of tree layer and the soil total nitrogen, Fe₂O₃, and CaO contents.

Effects of NaCl stress on photosynthesis characteristics and fast chlorophyll fluorescence induction dynamics of Pistacia chinensis  leaves.

LI Xu-xin1, LIU Bing-xiang1, GUO Zhi-tao2, CHANG Yue-xia1, HE Lei2, CHEN Fang2, LU Bing-she2,3

2013, 24(9):  2479-2484. 

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By using fast chlorophyll fluorescence induction dynamics analysis technique (JIP-test), this paper studied the photosynthesis characteristics and fast chlorophyll fluorescence induction dynamics of 1-year old Pistacia chinensis  seedlings under the stress of NaCl at the concentrations 0% (CK), 0.15%, 0.3%, 0.45%, and 0.6%. With the increasing concentration of NaCl, the contents of Chl a, Chl b, and Chl (a+b) in the seedlings leaves decreased, the Chl a/b ratio decreased after an initial increase, and the carotenoid content increased. The net photosynthetic rate (P_n) and stomatal conductance (g_s) decreased gradually with increasing NaCl concentration. The decrease of P_n was mainly attributed to the stomatal limitation when the NaCl concentration was lower than 0.3%, and to the nonstomatal limitation when the NaCl concentration was higher than 0.3%. The trapped energy flux per RC (TR_o/CS_o), electron transport flux per RC (ET_o/CS_o), density of RCs (RC/CS_o), and yield or flux ratio (ψ_o or φ_Eo) decreased, but the absorption flux per CS (ABS/CS_o) and the K phase (W_k) and J phase (V_j) in the O-J-I-P chlorophyll fluorescence induction curves increased distinctly, indicating that NaCl stress damaged the leaf oxygenevolving complex (OEC), donor sides, and PSⅡ reaction centers. When the NaCl concentration reached 0.3%, the maximum photochemical efficiency (F_v/F_m) and performance index (PI_ABS) decreased 17.7% and 36.6%, respectively, as compared with the control.

Variation characteristics of fine particulate matter PM_2.5 concentration in three urban recreational forests in Hui Mountain of Wuxi City, Jiangsu Province of East China.

GU Lin, WANG Cheng, WANG Xiao-lei, WANG Yan-ying, WANG Qian

2013, 24(9):  2485-2493. 

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It is of significance to understand the controlling effects of urban forest on atmospheric fine particulate matter PM_2.5 pollution. This paper monitored the variations of atmospheric PM_2.5 concentrations in three typical urban recreational forests (Cinnamomum camphora, Pinus elliotii, and Quercus variabilis ) in the Hui Mountain of Wuxi City during the day time (5:00 am-19:00 pm) in autumn and winter, 2011 and in spring and summer, 2012. The meteorological factors were observed simultaneously. The average annual PM_2.5 concentration in the three recreational forests was lower than that above the nearby roads, and this concentration in C. camphora and P. elliotii forests was lower than that in Q. variabilis forest. The average annual PM_2.5 concentration in the forests and above the nearby roads was lower than the background value in the downtown area of the City. The PM_2.5 concentration in the three recreational forests was the lowest in summer, followed by in autumn, and the highest in spring. In addition, the PM_2.5 concentration was the lowest in P. elliotii forest in spring, summer, and winter, and in C. camphora forest in autumn, but relatively higher in Q. variabilis forest in all seasons. The diurnal variation of the PM_2.5 concentration in the three forests in four seasons all showed nearly “one peak and one vale”, with the peak and vale appeared at 7:00-9:00 and 15:00-19:00, respectively. The PM_2.5 concentration was significantly correlated with the air moisture and temperature in four seasons, and significantly correlated with the light intensity in winter. Mild winds throughout the seasons had little effects on the PM_2.5 concentration.

Characteristics of soil nematode community in Abies georgei var. smithii forest gaps in southeast Tibet, China.

XUE Hui-ying1, LUO Da-qing2

2013, 24(9):  2494-2502. 

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In order to understand the characteristics of soil nematode community in the Abies georgei var. smithii forest gaps in southeast Tibet, an investigation was conducted to study the variations of soil nematode community at different depths of 0-30 cm soil layer in the gaps and nongaps. The nematode individual density, diversity index, and trophic group index were taken to analyze the composition and structural characteristics of the soil nematode community. A total of 26801 soil nematodes belonging to 2 classes, 5 orders, and 64 genera were collected by shallow dish method. The nematode individual density was averagely 3552 ind·100 g^-1 dry soil, and the individuals had a highly surface-gathering characteristics. In the gap soils, the dominant genera were Tylencholaimus and Filenchus, while the dominant trophic group was bacterivores. The soil organic matter was decomposed by both bacteria and fungi. The ecological index results showed that the nematodes diversity and richness were related to gap size. The characteristics of soil nematode community in the gaps were different from those in closed stand and forest open land, and this difference indicated the potential for using nematodes as the environmental indicator species.

Molecular diversity of arbuscular mycorrhizal fungi in wild and cultured Gynostemma pentaphyllum roots in Xishuangbanna, Southwest China.

ZHOU Li-si, GUO Shun-xing

2013, 24(9):  2503-2510. 

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By using nested-PCR, DNA cloning, and sequencing techniques, this paper studied the diversity of the community structure of arbuscular mycorrhizal fungi (AMF) in wild and cultured Gynostemma pentaphyllum roots. A total of 551 clones containing 18S rDNA genes of AMF were obtained from the roots. After the analysis of the restriction fragment length polymorphism, 100 different RFLP types were obtained, which were further divided into 20 AMF phylotypes belonging to seven families. The comparison of the sequences of 20 AMF phylotypes with the GenBank database showed that there were 5 AMF phylotypes having high similarity to the sequences of reported AMF species Glomus viscosum, Claroideoglomus etunicatum, Racocetra tropicana, Acaulospora spinosa, and Acaulospora mellea, respectively. These sequences were then assessed for the similarities against the MaarjAM database, and 12 phylotypes showed high similarity to the corresponding molecular virtual taxa, of which, 7 phylotypes were not obtained by the morphological identification of soil asexual spores. Statistical analysis indicated that there were significant differences in the AMF community between wild and cultured G. pentaphyllum roots. The analysis of relative abundance data indicated that Glo₂, Amb₁, and Para₁ were the dominant phylotypes in wild G. pentaphyllum roots, while Glo₃, Glo₈, Glo₁₀, and Div₁ were the prevalent phylotypes in cultured ones. Claroideoglomeraceae and Ambisporaceae were only detected in wild G. pentaphyllum roots, and Diversisporaceae was only identified in cultured ones.

Endophytic bacterial diversity in Codonopsis pilosula, Ephedra sinica, and Lamiophlomis rotate: A study with LH-PCR.

LI Xiao-lin1,2, JIANG Hua-ming2,3, ZHANG Bo2, TANG Guo-qing4, Petri Penttinen5, ZENG Zhen5, ZHENG Lin-yong1, ZHANG Xiao-ping2

2013, 24(9):  2511-2517. 

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To investigate the endophytic bacterial diversity in the three medicinal plant species Codonopsis pilosula, Ephedra sinica, and Lamiophlomis rotata in Ganzi of Sichuan, Southwest China, the total DNA of the three species were extracted by stringent surface sterilization, and studied with length heterogeneityPCR (LH-PCR) method. For the same plant species, their root, stem, and leaf LH-PCR profiles were in a high level of similarity, with little differences in band richness. However, there existed great differences in the LH-PCR profiles among different plant species. C. pilosula had the biggest band richness, followed by E. sinica, and L. rotata. In the three plant species, the endophytic bacteria with an approximately 474 bp DNA length were dominant. The endophytic bacterial diversity of the plants was negatively correlated with rhizosphere soil available phosphorus content, but positively correlated with rhizosphere soil pH. Elevation and rhizosphere soil total nitrogen content were the important environmental factors affecting the distribution of enophytic bacteria in these plant species. The information of population diversity obtained from LH-PCR could more intuitively reflect the differences of bacterial diversity among different plant species, and thus, LH-PCR would be available to be used for analyzing the endophytic bacterial diversity in medicinal plants, providing information and guidance for the further isolation of microbial resources.

CH₄ emission features of leading super-rice varieties and their relationships with the varieties growth characteristics in Yangtze Delta of China.

YAN Xiao-jun1, WANG Li-li1, JIANG Yu1, DENG Ai-xing2, TIAN Yun-lu3, ZHANG Wei-jian1,2

2013, 24(9):  2518-2524. 

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A pot experiment was conducted to study the CH₄ emission features of fourteen leading super-rice varieties (six Japonica rice varieties and eight Indica hybrid rice varieties) and their relationships with the varieties growth characteristics in Yangtze Delta. Two distinct peaks of CH₄ emission were detected during the entire growth period of the varieties, one peak occurred at fulltillering stage, and the other appeared at booting stage. The average total CH₄ emission of Japonica rice varieties was 37.6% higher than that of the Indica hybrid rice varieties (P<0.01), and the differences in the CH₄ emission between rice types occurred at the postanthesis phase. For all the varieties, there was a significant positive correlation between the total CH₄ emission and the maximum leaf area, but the correlations between the CH₄ emission and the other growth characteristics varied with variety type. The total CH₄ emission of Japonica rice varieties had a significant positive correlation with plant height, while the correlations between the total CH₄ emission of Indica hybrid rice varieties and their plant height were not significant. The total CH₄ emission of Indica hybrid rice varieties had significant negative correlations with the total aboveground biomass, grain yield, and harvest index, but the correlations were not significant for Japonica rice varieties. The lower CH₄ emission of Indica hybrid rice varieties was likely due to their significantly higher root biomass, as compared with Japonica rice varieties.

Effects of water and nitrogen regulation on the yield and water and nitrogen use efficiency of cotton in south Xinjiang, Northwest China under plastic mulched drip irrigation.

DENG Zhong1,2, BAI Dan1, ZHAI Guo-liang2, ZONG Jie2, LI Ying2, CAI Jiu-mao2, FENG Jun-jie1,2

2013, 24(9):  2525-2532. 

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A field experiment with three irrigation amounts and five nitrogen application levels was conducted to investigate the effects of water and nitrogen regulation on the growth characteristics, yield component factors, and water and nitrogen use efficiency of cotton in south Xinjiang under mulched drip irrigation. With the increasing amount of irrigation, the plant height, leaf number on main stem, boll number, LAI, and dry matter accumulation in leaf and stem improved significantly, but the root growth was restrained. As compared with low and high irrigation amounts (4950 and 6750 mm·hm^-2, respectively), medium irrigation amount (5850 mm·hm^-2) increased the available bolls per plant and the single boll mass averagely by 0.96 and 0.4 and by 0.22 and 0.11 g, respectively. When the nitrogen application level was 300 kg·hm^-2, as compared with other nitrogen application levels, the stem diameter increased significantly, and the growth of bud, boll, and root was accelerated. Moreover, the allocation ratio of dry matter from nutritional organs to reproductive organs under medium irrigation amount increased by 5.1% and 29.6% respectively, as compared with that under low and high irrigation amounts. Irrigation amount had significant effects on the cotton yield but little effects on the lint percentage, whereas nitrogen application level had definite effects on the cotton yield and lint percentage. However, low irrigation amount restrained the effects of nitrogen application on yield enhancement. In this experiment, when the irrigation amount was 5850 mm·hm^-2 and the nitrogen application level was 300 kg·hm^-2, the cotton grew healthily, the plant shape structure was optimized, the dry matter allocation to reproductive organs was promoted dramatically, the available bolls, single boll mass, and lint percentage increased, the cotton yield reached the highest (6992.33 kg·hm^-2), and the water and nitrogen use efficiency amounted to 1.45 kg·m^-3 and 45.9%, respectively.

Effects of different multiple cropping systems on paddy field weed community under long term paddy-upland rotation.

YANG Bin-juan, HUANG Guo-qin, XU Ning, WANG Shu-bin

2013, 24(9):  2533-2538. 

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Based on a long term field experiment, this paper studied the effects of different multiple cropping systems on the weed community composition and species diversity under paddy-upland rotation. The multiple cropping rotation systems could significantly decrease weed density and inhibited weed growth. Among the rotation systems, the milk vetch-early rice-late maize → milk vetch-early maize intercropped with early soybean-late rice (CCSR) had the lowest weed species dominance, which inhibited the dominant weeds and decreased their damage. Under different multiple cropping systems, the main weed community was all composed of Monochoia vaginalis, Echinochloa crusgalli, and Sagittaria pygmae, and the similarity of weed community was higher, with the highest similarity appeared in milk vetch-early rice-late maize intercropped with late soybean → milk vetch-early maize-late rice (CSCR) and in CCSR. In sum, the multiple cropping rotations in paddy field could inhibit weeds to a certain extent, but attentions should be paid to the damage of some less important weeds.

Effects of planting years of vegetable solar greenhouse on soil microbial flora and enzyme activities.

YANG Qin, LI Liang

2013, 24(9):  2539-2544. 

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Taking the vegetable solar greenhouses having been planted for 2, 4, 6, 11, 13, 16, and 19 years as test objects, and with the open vegetable field as the control, this paper studied the variations of soil microbial flora and enzyme activities. With the increasing years of planting, the numbers of soil bacteria, actinomycetes, and total microbes in vegetable solar greenhouses decreased after an initial increase, and reached the maximum in the greenhouse of 11 years planting, with a significant increment of 54.8%, 63.7%, and 55.4%, respectively, as compared to the control. The number of soil fungi in the vegetable solar greenhouses increased steadily with increasing planting years, being about 2.2 times higher in the greenhouse of 11 years planting. Among the microbial physiological groups, the numbers of aerobic cellulosedecomposer, aerobic azotobacter, nitrite bacteria, denitrifier, and sulphur reducer showed the same variation trend as the soil bacteria’s, and those in the greenhouse of 11 years planting being 1.5, 1.6, 1.9, 1.4, and 1.1 times of the control, respectively. The number of ammonifiers increased after an initial decrease, reached the minimum in the greenhouse of 13 years planting, being only 56.0% of the control. The enzyme activities of soil urease, polyphenol oxidase, sucrase, protease, cellulase, and alkaline phosphatase increased firstly and then decreased with the increasing years of planting, but soil catalase activity was relatively stable. Correlation analysis showed that the numbers of soil bacteria, actinomycetes, and total microbes were significantly positively correlated with all test soil enzyme activities, while the number of soil fungi had significant negative correlation with the activity of soil catalase.

Impacts of drought stress on leaf osmotic adjustment and chloroplast ultrastructure of stay-green sorghum.

ZHOU Yu-fei, WANG De-quan, LU Zhang-biao, WANG Na, WANG Yi-tao, LI Feng-xian, XU Wen-juan, HUANG Rui-dong

2013, 24(9):  2545-2550. 

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Taking stay-green sorghum (B35) and non-stay green sorghum (Sanchisan) as test materials, a pot experiment was conducted to study their leaf osmotic adjustment and chloroplast ultrastructure at flowering and filling stages under impacts of drought stress (45%-50% of maximum field capacity). For the two sorghum lines, drought stress caused the reduction of their leaf free water content and relative water content, and increased the leaf bound water content, water saturation deficit, and electrical conductivity, with the increment or dement being larger for Sanchisan than for B35. Drought stress increased the leaf soluble sugar content and proline content, with the increment of the soluble sugar content being larger for Sanchisan and the increment of the proline content being larger for B35, while decreased the leaf soluble protein content, with the decrement being larger for Sanchisan than for B35. The chloroplast ultrastructure of both B35 and Sanchisan under drought stress was damaged to some extent, but the damaged degree was obviously lower for B35 than for Sanchisan. The findings indicated that stay-green sorghum had a greater adaptation to drought stress through stronger osmotic adjustment.

Effects of different organic fertilizers on the microbes in rhizospheric soil of flue-cured tobacco.

ZHANG Yun-wei, XU Zhi, TANG Li, LI Yan-hong, SONG Jian-qun, XU Jian-qin

2013, 24(9):  2551-2556. 

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A field experiment was conducted to study the effects of applying different organic fertilizers (refined organic fertilizer and bio-organic fertilizer) and their combination with 20% reduced chemical fertilizers on the microbes in rhizospheric soil of fluecured tobacco, the resistance of the tobacco against bacterial wilt, and the tobacco yield and quality. As compared with conventional chemical fertilization (CK), applying refined organic fertilizer (ROF) or bio-organic fertilizer (BIO) in combining with 20% reduced chemical fertilization increased the bacterial number and the total microbial number in the rhizospheric soil significantly. Applying BIO in combining with 20% reduced chemical fertilization also increased the actinomyces number in the rhizospheric soil significantly, with an increment of 44.3% as compared with that under the application of ROF in combining with 20% reduced chemical fertilization, but decreased the fungal number. As compared with CK, the ROF and BIO increased the carbon use capacity of rhizospheric microbes significantly, and the BIO also increased the capacity of rhizospheric microbes in using phenols significantly. Under the application of ROF and BIO, the disease incidence and the disease index of bacterial wilt were decreased by 4% and 8%, and 23% and 15.9%, and the proportions of high grade tobacco leaves increased significantly by 10.5% and 9.7%, respectively, as compared with those in CK. BIO increased the tobacco yield and its output value by 17.1% and 18.9%, respectively, as compared with ROF.

Effects of irrigation scheme on the grain glutenin macropolymer’s size distribution and the grain quality of winter wheat with strong gluten.

ZHOU Xiao-yan1,2, JIA Dian-yong1, DAI Xing-long1, HE Ming-rong1

2013, 24(9):  2557-2563. 

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Taking two winter wheat (Triticum aestivum L.) cultivars (Gaocheng 8901 and Jimai 20) with high quality strong gluten as test materials, a 2-year field experiment was conducted to study the grain glutenin macropolymer (GMP)’s content and size distribution, grain quality, and grain yield under effects of different irrigation schemes. The schemes included no irrigation in whole growth period (W₀), irrigation once at jointing stage (W₁), irrigation two times at wintering and jointing stages (W₂), respectively, and irrigation three times at wintering, jointing, and filling stages (W₃), respectively, with the irrigation amount in each time being 675 m³·hm^-2. Among the test irrigation schemes, W₂ had the best effects on the dough development time, dough stability time, loaf volume, grain yield, GMP content, weighted average surface area of particle D_3,2, weighted average volume of particle D_4,3, and volume percent and surface area percent of particle size >100 μm of the two cultivars. The dough development time, dough stability time, and loaf volume were negatively correlated with the volume percent of GMP particle size <10 μm and 10-100 μm, while positively correlated with the volume percent of GMP particle size >100 μm, D_3,2, and D_4,3. It was suggested that both water deficit and water excess had detrimental effects on the grain yield and grain quality, and irrigation level could affect the wheat grain quality through altering GMP particle size distribution.

Spatiotemporal variation patterns of potential evapotranspiration in five provinces of Northwest China in 1960-2011.

LIU Xian-feng1, PAN Yao-zhong1,ZHANG Jin-shui1, LIN Zhi-hui2

2013, 24(9):  2564-2570. 

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By using Penman-Monteith model and Hurst index model, this paper analyzed the spatiotemporal variation patterns of potential evapotranspiration (ET₀) in the five provinces of Northwest China in 1960-2011. In the meantime, the dominant factors driving the variations of the ET₀ were quantitatively analyzed by using sensitivity analysis method. In 1960-2011, the ET₀ in the five provinces presented an overall decreasing trend, with a drop rate of -0.72 mm·a^-1, but the ET₀ increased gradually after 1993. An obvious spatial difference was shown in the annual average ET₀. The average ET₀ in the five provinces was 1158 mm (675-2282 mm), wit the maximum (2282 mm) in Qijiaojing of Xinjiang and the low values (>800 mm) in Qinba Mountains in south Shaanxi. Except in spring, the ET₀ in other seasons showed a decreasing trend. In the analysis of future trend, the ET₀ in most areas (81.4%) of Northwest China would present a trend from decrease to increase. Therefore, under the background of global warming, the warm and wet degree in Northwest China would be somewhat weakened, but the ET₀ in the middle part of Xinjiang would be decreased continuously. Wind speed was the main factor affecting the ET₀ in Northwest China at both annual and monthly scales, but the affecting extent of wind speed differed with seasons and areas. The spatial extent affected by the wind speed in winter expanded across the entire five provinces of Northwest China, while the spatial extent affected by the wind speed in summer included the entire Xinjiang and the northwest of Gansu and Qinghai.

Characteristics of heat resource in mountainous region of northern Guangdong, South China based on three-dimensional climate observation.

LIU Wei1,2,3,4, WANG Chun-lin1, CHEN Xin-guang1, CHEN Hui-hua1

2013, 24(9):  2571-2580. 

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Based on the 2009-2011 daily air temperature observation data from 11 automatic weather stations in the mountainous region of northern Guangdong, this paper calculated the heat factors in the region, including the beginning date of 10 ℃, the ending date of 15 ℃, the duration days of 10-15 ℃, the accumulated temperature above 10 ℃, the days of minimum temperature below 5 ℃, and the mean monthly temperature,  with the linear regression model of the heat factors and latitude established. In 2009-2011, the heat factors in the region had significant correlations with latitude, and the heat resource at the same latitudes differed apparently between south and north slopes. With the increase of latitude, the beginning date of 10 ℃ delayed, the ending date of 10 ℃ advanced, and the duration days of 10-15 ℃, the accumulated temperature above 10 ℃, the days of temperature above 10 ℃, and the mean annual air temperature decreased. The vertical variation rates of the heat factors were larger on south slope than on north slope. The results of this study could be used for fitting the vertical distribution of heat resource in the areas with no weather station, and provide basis for the fine regionalization of agricultural climate.

Assessment of the impacts of soil erosion on water environment based on the integration of soil erosion process and landscape pattern.

LIU Yu, WU Bing-fang, ZENG Yuan, ZHANG Lei

2013, 24(9):  2581-2589. 

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The integration of the effects of landscape pattern to the assessment of the impacts of soil erosion on eco-environmental is of practical significance in methodological prospect, being able to provide an approach for identifying water body’s sediment source area, assessing the potential risks of sediment export of on-site soil erosion to the target water body, and evaluating the capacity of regional landscape pattern in preventing soil loss. In this paper, the RUSLE model was applied to simulate the on-site soil erosion rate. With the consideration of the soil retention potential of vegetation cover and topography, a quantitative assessment was conducted on the impacts of soil erosion in the water source region of the middle route for SouthtoNorth Water Transfer Project on rivers and reservoirs by delineating landscape pattern at point (or cell) scale and sub-watershed level. At point (or  grid cell) scale, the index of soil erosion impact intensity (I) was developed as an indicator of the potential risk of sediment export to the water bodies. At subwatershed level, the landscape leakiness index (LI) was employed to indicate the sediment retention capacity of a given landscape pattern. The results revealed that integrating the information of landscape pattern and the indices of soil erosion process could spatially effectively reflect the impact intensity of in situ soil erosion on water bodies. The LI was significantly exponentially correlated to the mean sediment retention capacity of landscape and the mean vegetation coverage of watershed, and the sediment yield at sub-watershed scale was significantly correlated to the LI in an exponential regression. It could be concluded that the approach of delineating landscape pattern based on soil erosion process and the integration of the information of landscape pattern with its soil retention potential could provide a new approach for the risk evaluation of soil erosion.

Characteristics and adaptation of seasonal drought in southern China under the background of global climate change.  Ⅳ. Spatiotemporal characteristics of drought for maize based on crop water deficit index.

SUI Yue1,2, HUANG Wan-hua1,3, YANG Xiao-guang1, LI Mao-song4

2013, 24(9):  2590-2598. 

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Based on the 1959-2008 meteorological data from 249 meteorological stations in southern China, and by using crop water deficit index (CWDI) as the agricultural drought index, this paper calculated the drought frequency and drought stations ratio in this region, and analyzed the spatiotemporal distribution characteristics of drought for spring maize and summer maize during their growth periods. As for the spatial pattern of drought frequency, the drought for spring maize was more severe in the north of Huaihe River, northern Yunnan, and southern South China, but was lighter in the other regions. Except that the drought for summer maize at its late developmental stage was more severe in the middle-lower reaches of Yangtze River, northern South China, and eastern Southwest China, the drought for summer maize at its other developmental stages within southern China was lighter. As for the variation trend of drought intensity and drought area, the drought intensity of spring maize from its seven-leaf stage to jointing stage in the middlelower reaches of Yangtze River increased obviously, while the drought intensity and drought area of the spring maize from its late spinning stage to milky maturity stage presented a decreasing trend. The drought of summer maize from its late jointing stage to tasseling stage and from late spinning stage to milky maturity stage all showed a decreasing trend. In Southwest China, the drought intensity and drought area for spring maize and summer maize had no clear trend. From the viewpoint of the inter-annual and decadal variability of drought intensity and drought area, there was a larger variation for the summer maize in the middle-lower reaches of Yangtze River, but less difference in Southwest China.

Simulation of urban ecological security pattern based on cellular automata: A case of Dongguan City, Guangdong Province of South China.

YANG Qing-sheng1, QIAO Ji-gang1, AI Bin2

2013, 24(9):  2599-2607. 

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Taking the Dongguan City with rapid urbanization as a case, and selecting landscape ecological security level as evaluation criterion, the urbanization cellular number of 1 km×1 km ecological security cells was obtained, and imbedded into the transition rules of cellular automata (CA) as the restraint term to control urban development, establish ecological security urban CA, and simulate ecological security urban development pattern. The results showed the integrated landscape ecological security index of the City decreased from 0.497 in 1998 to 0.395 in 2005, indicating that the ecological security at landscape scale was decreased. The CA- simulated integrated ecological security index of the City in 2005 was increased from the measured 0.395 to 0.479, showing that the simulated urban landscape ecological pressure from human became lesser, ecological security became better, and integrated landscape ecological security became higher. CA could be used as an effective tool in researching urban ecological security.

An improved method and its application for agricultural drought monitoring based on remote sensing.

ZHENG You-fei1, CHENG Jin-xin1, WU Rong-jun1, GUAN Fu-lai2, YAO Shu-ran2

2013, 24(9):  2608-2618. 

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From the viewpoint of land surface evapotranspiration, and by using the semi-empirical evapotranspiration model based on the Priestley-Taylor equation and the land surface temperature-vegetation index (LST-VI) triangle algorithm, the current monitoring technology of agricultural drought based on remote sensing was improved, and a simplified Evapotranspiration Stress Index (SESI) was derived. With the application of the MODIS land products from March to November in 2008 and 2009, the triangle algorithm modeling with three different schemes was constructed to calculate the SESI to monitor the agricultural drought in the plain areas of Beijing, Tianjin, and Hebei, in comparison with the Temperature Vegetation Dryness Index (TVDI). The results showed that SESI could effectively simplify the remote sensing drought monitoring method, and there was a good agreement between SESI and surface soil (10 and 20 cm depth) moisture content. Moreover, the performance of SESI was better in spring and autumn than in summer, and the SESI during different periods was more comparable than TVDI. It was feasible to apply the SESI to the continuous monitoring of a large area of agricultural drought.

Effects of strong reductive approach on remediation of degraded facility vegetable soil.

ZHU Tong-bin, MENG Tian-zhu, ZHANG Jin-bo, CAI Zu-cong

2013, 24(9):  2619-2624. 

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High application rate of chemical fertilizers and unreasonable rotation in facility vegetable cultivation can easily induce the occurrence of soil acidification, salinization, and serious soilborne diseases, while to quickly and effectively remediate the degraded facility vegetable soil can considerably increase vegetable yield and farmers’ income. In this paper, a degraded facility vegetable soil was amended with 0, 3.75, 7.50, and 11.3 t C·hm^-2 of airdried alfalfa and flooded for 31 days to establish a strong reductive environment, with the variations of soil physical and chemical properties and the cucumber yield studied. Under the reductive condition, soil Eh dropped quickly below 0 mV, accumulated soil NO₃^- was effectively eliminated, soil pH was significantly raised, and soil EC was lowered, being more evident in higher alfalfa input treatments. After treated with the strong reductive approach, the cucumber yield in the facility vegetable field reached 53.3-57.9 t·hm^-2, being significantly higher than that in un-treated facility vegetable field in last growth season (10.8 t·hm^-2). It was suggested that strong reductive approach could effectively remediate the degraded facility vegetable soil in a short term.

Pollution characteristics and ecological risk assessment of heavy metals in surface sediments of Qingshan Reservoir in Lin’an City, Zhejiang Province of East China.

ZHANG Fen, YANG Chang-ming, PAN Rui-jie

2013, 24(9):  2625-2630. 

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A total of 8 representative surface sediment sampling sites were collected from the Qingshan Reservoir in Lin’〖KG-*4〗an City of Zhejiang Province to investigate the differences in the total concentrations of As, Cr, Cu, Ni, Mn, Pb, and Zn among the sampling sites. The different forms of the heavy metals, i.e., acid soluble, easily reducible, easily oxidizable, and residual, were determined by BCR sequential extraction method, and the pollution degrees and potential ecological risks of the heavy metals in the surface sediments at different sampling sites of the Reservoir were assessed by using geoaccumulation index (I_geo) and Hakanson potential ecological risk index. There existed obvious spatial differences in the total concentrations of the heavy metals in the surface sediments of the Reservoir. The sampling sites nearby the estuaries of the tributaries flowing through downtowns and heavy industrial parks to the Reservoir had obviously higher heavy metals concentrations in surface sediments, as compared to the other sampling sites. In the sediments, Mn was mainly in acid extractable form, Cu and Pb were mainly in reducible form, and As was mainly in residual form. The surface sediments at the sampling sites nearby the estuaries of the tributaries flowing through downtowns to the Reservoir had higher proportions of acid extractable and reducible forms of the heavy metals, which would have definite potential toxic risk to aquatic organisms. Among the 7 heavy metals in the surface sediments, As showed the highest pollution degree, followed by Cu, Ni, Mn, Pb, and Zn, which were at moderate pollution degree, while Cr was at non-pollution degree, with relatively low potential ecological risk. Through the comparison of the sampling sites, it was observed that the surface sediments at the sites nearby the estuaries of Jinxi River and Hengxi River flowing through downtowns and heavy industrial parks to the Reservoir showed obviously higher heavy metals pollution degree and potential ecological risk.

Spatial heterogeneity in body condition of small yellow croaker in Yellow Sea and East China Sea based on mixed-effects model and quantile regression analysis.

LIU Zun-lei1,2, YUAN Xing-wei1,2, YAN Li-ping1,2, YANG Lin-lin1,2, CHENG Jia-hua1,2

2013, 24(9):  2631-2642. 

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By using the 2008-2010 investigation data about the body condition of small yellow croaker in the offshore waters of southern Yellow Sea (SYS), open waters of northern East China Sea (NECS), and offshore waters of middle East China Sea (MECS), this paper analyzed the spatial heterogeneity of body length-body mass of juvenile and adult small yellow croakers by the statistical approaches of mean regression model and quantile regression model. The results showed that the residual standard errors from the analysis of covariance (ANCOVA) and the linear mixed-effects model were similar, and those from the simple linear regression were the highest. For the juvenile small yellow croakers, their mean body mass in SYS and NECS estimated by the mixed-effects mean regression model was higher than the overall average mass across the three regions, while the mean body mass in MECS was below the overall average. For the adult small yellow croakers, their mean body mass in NECS was higher than the overall average, while the mean body mass in SYS and MECS was below the overall average. The results from quantile regression indicated the substantial differences in the allometric relationships of juvenile small yellow croakers between SYS, NECS, and MECS, with the estimated mean exponent of the allometric relationship in SYS being 2.85, and the interquartile range being from 2.63 to 2.96, which indicated the heterogeneity of body form. The results from ANCOVA showed that the allometric body length-body mass relationships were significantly different between the 25^th and 75^th percentile exponent values (F=6.38, df=1737, P<0.01) and the 25^th percentile and median exponent values (F=2.35,df=1737,P=0.039). The relationship was marginally different between the median and 75^th percentile exponent values (F=2.21, df=1737, P=0.051). The estimated body lengthbody mass exponent of adult small yellow croakers in SYS was 3.01 (10^th and 95th percentiles=2.77 and 3.1, respectively). The estimated body lengthbody mass relationships were significantly different from the lower and upper quantiles of the exponent (F=3.31, df=2793, P=0.01) and the median and upper quantiles (F=3.56,df=2793, P<0.01), while no significant difference was observed between the lower and median quantiles (F=0.98, df=2793, P=0.43).

Distribution pattern of microphytoplankton in the Bering Sea during the summer of 2010.

LIN Geng-ming, YANG Qing-liang, WANG Yu

2013, 24(9):  2643-2650. 

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Based on the analysis of 70 water samples collected by the Chinese icebreaker Xuelong in the areas of 52°42.29′-65°30.23′ N and 169°20.85′ E-179°30.37′ W in the Bering Sea during the Chinese Arctic Research Expedition on July 10-19, 2010, a total of 143 phytoplankton species were identified, including 95 diatom species belonging to 37 genera, 44 dinoflagellate species belonging to 15 genera, 2 Chlorophyta species belonging to 2 genera, 1 Euglenophyta belonging to 1 genus, and 1 Chrysophyta species belonging to 1 genus. The cluster analysis revealed that the phytoplankton in the study areas could be divided as oceanic and shallow water groups. The oceanic group found in the western North Pacific Ocean and the Bering Basin was dominated by the boreal oceanic species such as Neodenticula seminae and Chaetoceros atlanticus and the cosmopolitan species such as Thalassionema nitzschioides and Chaetoceros compressus, with the characteristics of low abundance and high evenness of diversified species. The shallow water group found in the continental shelf and slope of Bering Sea was mostly composed of the panarctic neritic species such as Thalassiosira nordenskioldi and Chaetoceros furcellatus and the cosmopolitan species such as Leptocylindrus danicus and Chaetoceros curvisetus, with the characteristics of low species diversity and evenness index due to the high abundance in certain species. The phytoplankton abundance in the surface water layer distributed unevenly among the stations, ranging from 950 to 192400 cells·L^-1 and with an average of 58722 cells·L^-1. Horizontally, the abundance distribution trend was decreased in the order of the Bering Sea shelf, the Bering Sea slope, the Bering Sea basin, and the western North Pacific Ocean. Vertically, the abundance was lower in surface layer and maximized in the thermocline, suggesting that the phytoplankton abundance in vertical distribution  varied with the regional thermocline.

Effects of herb residue vermicompost on maize growth and soil fertility.

LI Jing-juan, ZHOU Bo, ZHANG Chi, ZHANG Jing, XU Huan, YANG Xiao-xue, CHEN Xu-fei, DAI Jun

2013, 24(9):  2651-2657. 

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A pot experiment was conducted to evaluate the effects of herb residue vermicompost on maize growth and soil fertility. With the increasing application rate of vermicompost, the plant height, stem diameter, leaf area, and chlorophyll content of maize all increased significantly. After 60 days growth of maize, the soil bulk density in most vermicompost treatments decreased significantly. The soil pH in vermicompost treatments was significantly higher than that in CK and in chemical fertilization treatments. In addition, the soil total nitrogen and organic matter contents in vermicompost treatments were obviously higher than those in chemical fertilization treatments. It was suggested that herb residue vermicompost could be used as an efficient and high-quality organic fertilizer, and its appropriate application could improve soil physical structure, alleviate soil acidification, increase soil organic matter and nitrogen contents, and promote crop growth.

Effects of global climate change on the C, N, and P stoichiometry of terrestrial plants.

HONG Jiang-tao1,2, WU Jian-bo1, WANG Xiao-dan1

2013, 24(9):  2658-2665. 

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The response patterns of biogeochemical cycle and the adaptation strategies of terrestrial plants under the background of global climate change have received extensive attention. This paper analyzed the effects of climate warming and precipitation change on the plant C:N:P in different ecosystems, the effects of elevated atmospheric CO2 on the plant nutrients in different photosynthetic pathways, and the shortterm and longterm effects of the responses of soilplant nutrients to nitrogen deposition, and explored the possible underlying mechanisms in terms of the plant physiological properties in relation to soil available nutrients, which could provide theoretical bases for studying the nutrients (C, N and P) transmission and regulation mechanisms between soil and plant, the structure and function of terrestrial ecosystems, and the responses of biogeochemical cycle to global climate change. The existing problems and the further research directions in this study area were proposed.

Effects of biochar on soil nitrogen cycle and related mechanisms: A review.

PAN Yi-fan, YANG Min, DONG Da, WU Wei-xiang

2013, 24(9):  2666-2673. 

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Biochar has its unique physical and chemical properties, playing a significant role in soil amelioration, nutrient retention, fertility improvement, and carbon storage, and being a hotspot in the research areas of soil ecosystem, biogeochemical cycling, and agricultural carbon sequestration. As a kind of anthropogenic materials, biochar has the potential in controlling soil nitrogen (N) cycle directly or indirectly, and thus, has profound effects on soil ecological functions. This paper reviewed the latest literatures regarding the effects of biochar applications on soil N cycle, with the focuses on the nitrogen species adsorption and the biochemical processes (nitrification, denitrification, and nitrogen fixation）,  and analyzed the related action mechanisms of biochar. The future research areas for better understanding the interactions between biochar and soil N cycle were proposed.

Lightning-caused fire, its affecting factors and prediction: A review.

ZHANG Ji-li, BI Wu, WANG Xiao-hong, WANG Zi-bo, LI Di-fei

2013, 24(9):  2674-2684. 

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Lightning-caused fire is the most important natural fire source. Its induced forest fire brings enormous losses to human beings and ecological environment. Many countries have paid great attention to the prediction of lightning-caused fire. From the viewpoint of the main factors affecting the formation of lightning-caused fire, this paper emphatically analyzed the effects and action mechanisms of cloudtoground lightning, fuel, meteorology, and terrain on the formation and development process of lightningcaused fire, and, on the basis of this, summarized and reviewed the logistic model, K-function, and other mathematical methods widely used in prediction research of lightningcaused fire. The prediction methods and processes of lightning-caused fire in America and Canada were also introduced. The insufficiencies and their possible solutions for the present researches as well as the directions of further studies were proposed, aimed to provide necessary theoretical basis and literature reference for the prediction of lightningcaused fire in China.

Effects of transgenic crops on soil microorganisms: A review.

ZHANG Yan-jun, XIE Ming， PENG De-liang

2013, 24(9):  2685-2690. 

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The worldwide cultivation of transgenic crops not only provides tremendous economic benefits, but also induces the concern about the potential risks of transgenic crops on soil ecosystem in which microorganisms are involved. The potential effects of transgenic crops on soil microorganisms include the direct effects of the transgenic proteins on nontarget soil microorganisms, and the indirect effects of the unintentional changes in the chemical compositions of root exudates induced by the introduction of the exogenous transgenic proteins. Most of the studies on transgenic crops suggested that transgenic crops could affect the quantity and structure of soil microbial populations. However, the perceivable effects on the soil microorganisms are inconsistent, with some in significant and others in non-significant, or some with persistent and others with nonpersistent. This paper summarized the effects of different transgenic crops on soil microorganisms, and discussed the factors affecting the assessment reliability, including the species of transgenic crops and the experimental technologies and principles. Some issues needed to be paid special attention to in the future studies were put forward.

History and present status of butterfly monitoring in Europe and related development strategies for China.

FANG Li-jun1, XU Hai-gen2, GUAN Jian-ling3

2013, 24(9):  2691-2698. 

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Butterfly is an important bio-indicator for biodiversity monitoring and ecological environment assessment. In Europe, the species composition, population dynamics, and distribution pattern of butterfly have been monitored for decades, and many long-term monitoring schemes with international effects have been implemented. These schemes are aimed to assess the regional and national variation trends of butterfly species abundance, and to analyze the relationships of this species abundance with habitat, climate change, and other environmental factors, providing basic data for researching, protecting, and utilizing butterfly resources and predicting environmental changes, and playing important roles in the division of butterfly’s threatened level, the formulation of related protection measures, and the protection and management of ecological environment. This paper reviewed the history and present status of butterfly monitoring in Europe, with the focus on the wellknown longterm monitoring programs, e.g., the UK Butterfly Monitoring Scheme and the Germany and European Union Butterfly Monitoring Scheme. Some specific proposals for conducting butterflies monitoring in China were suggested.

Phthalic acid esters (PAEs) pollution in farmland soils: A review.

WANG Kai-rong1,2, CUI Ming-ming1, SHI Yan-xi1

2013, 24(9):  2699-2708. 

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The environmental pollution and food safety problems caused by phthalic acid esters (PAEs) have been attracted extensive attention around the world. As a large PAEs producer and consumer, China is facing severe PAEs environmental pollution problems. This paper reviewed the present pollution status of six PAEs classified by the U.S. Environmental Protection Agency as the priority pollutants in China farmland soils, analyzed the sources of these six PAEs in this country, and discussed the absorption and accumulation characteristics of the PAEs in different crops as well as the bio-toxic effects of PAEs pollutants. The PAEs concentrations in China farmland soils are significantly higher those in the farmland soils of the United States and European countries. The main sources of PAEs in China farmland soils are atmospheric deposition, agricultural films, sewage sludge application, and wastewater irrigation. There exist significant differences in the characteristics of PAEs absorption, accumulation, and distribution among different crops. PAEs not only have negative effects on soil quality, crop growth, and crop physiological and biochemical properties, but also possess bio-accumulative characteristics. The weaknesses in current researches were pointed out, and the suggestions for the further researches were given, e.g., to expand the scope of PAEs pollution survey, to explore the toxic mechanisms of PAEs on crops, and to develop the techniques for in situ remediation of PAEspolluted soils.