Table of Content

18 February 2016, Volume 27 Issue 2

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Effect of seasonal high temperature and drought on carbon flux of bamboo forest ecosystem in subtropical region.

CHEN Xiao-feng1, JIANG Hong1,2*, NIU Xiao-dong1, ZHANG Jin-meng1, LIU Yu-li1, FANG Cheng-yuan1

2016, 27(2):  335-344. 

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The carbon flux of subtropical bamboo forest ecosystem was continuously measured using eddy covariance technique in Anji County of Zhejiang Province, China. The monthly net ecosystem productivity (NEP), ecosystem respiration (R_e) and gross ecosystem productivity (GEP) data from 2011 to 2013 were selected to analyze the impacts of seasonal high temperature and drought on the carbon flux of bamboo forest ecosystem. The results showed that there were big differences among annual NEP of bamboo forest from 2011 to 2013. Because of the asynchronization of precipitation and heat, the seasonal high temperature and drought in July and August of 2013 caused significant decline in NEP by 59.9% and 80.0% when compared with the same months in 2011. Correlation analysis of the NEP, R_e, GEP and environmental factors suggested that the atmosphere temperatures were significantly correlated with R_e and GEP in 2011 and 2013 （P<0.05）. However, to air and soil moisture, R_e and GEP had different responses, that was, GEP was more vulnerable by the decrease of the soil moisture compared with R_e. Besides, the raising of saturation vapour pressure promoted the R_e modestly but inhibited the GEP, which was supposed to be the main reason for NEP decrease of bamboo forest ecosystem in Anji from July to August in 2013.

Dynamics of sap flow density in stems of typical desert shrub Calligonum mongolicum and its responses to environmental variables.

Shi-qin1,2*, JI Xi-bin1, JIN Bo-wen1

2016, 27(2):  345-353. 

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Independent measurements of stem sap flow in stems of Calligonum mongolicum and environmental variables using  commercial sap flow gauges and a micrometeorological monitoring system, respectively, were made to simulate the variation of sap flow density in the middle range of Hexi Corridor, Northwest China
during June to September, 2014. The results showed that the diurnal process of sap flow density in C. mongolicum showed a broad unimodal change, and the maximum sap flow density reached about 30 minutes after the maximum of photosynthetically active radiation (PAR), while about 120 minutes before the maximum of temperature and vapor pressure deficit (VPD). During the studying period, sap flow density closely related with atmosphere evaportranspiration demand, and mainly affected by PAR, temperature and VPD. The model was developed which directly linked the sap flow density with climatic variables, and good correlation between measured and simulated sap flow density was observed in different climate conditions. The accuracy of simulation was significantly improved if the time-lag effect was taken into consideration, while this model underestimated low and nighttime sap flow densities, which was probably caused by plant physiological characteristics.

Response of Picea purpurea and Abies faxoniana tree rings at different slope aspects to rapid warming in western Sichuan, China.

GUO Bin-de1, ZHANG Yuan-dong2, WANG Xiao-chun1*

2016, 27(2):  354-364. 

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By using an empirical ‘signalfree’ standardization approach, we constructed four Picea purpurea and Abies faxoniana treering chronologies at southeast and northwest slope aspects of Erdaohai and east slope aspect of Zharisi, Songpan, west Sichuan, China. The response analysis and multivariate analysis of variance between tree rings and climatic variables were conducted to explore the divergent responses of tree growth at different slope aspects to the recent warming climate. Results showed that tree growth of P. purpurea at east slope aspect was obviously accelerated (0.011 a^-1) since rapid warming in 1980, whereas those at northwest slope aspect was significantly reduced (-0.006 a^-1). Tree growth of P. purpurea at southeast slope aspect and A. faxoniana at northwest slope aspect decreased in significantly. With the rapid warming, growthclimate relationships of P. purpurea and A. faxoniana  at different slope aspects changed significantly. After rapid warming in 1980, the promoting effects of growing season temperature (GST) on P. purpurea growth at east slope increased significantly, while the inhibitory effects of GST on its growth at southeast and northwest slopes also increased significantly. However, the effects of GST on A. faxoniana growth at northwest slope did not change significantly before and after rapid warming. The effects of precipitation in May (PM) on P. purpurea growth at east slope was changed from inhibition before rapid warming to significant promotion after rapid warming, while the inhibitory effects of PM on P. purpurea growth at southeast and northwest slopes increased significantly. For A. faxoniana at northwest slope, however, it did not change obviously before and after rapid warming. The response analysis between tree growth and the Palmer drought severity index (PDSI) showed that soil moisture variations at different slope aspects were an important reason of tree-ring growth response difference since rapid warming. In addition, the results of multivariate analysis of variance indicated that the combined effects of slope aspect, temperature and precipitation factors were the most important limited factors for tree growth variability in western Sichuan. Therefore, we should consider the combined effects of temperature, precipitation and different slope aspects when simulating and predicting tree-growth response to the recent climate warming trend.

C, N, P stoichiometric characteristics of tree, shrub, herb leaves and litter in forest community of Shaanxi Province, China.

JIANG Pei-pei1, CAO Yang2,3, CHEN Yun-ming2,3*

2016, 27(2):  365-372. 

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A total of 121 sampling sites were selected to study the C, N, P stoichiometric characteristics among the leaves of tree, shrub, herb and the litter of the majority forest community of Shaanxi Province, China. We also studied their relationships with geographical factors. The results showed that C, N concentrations were highest in tree leaf, P concentration was highest in herb leaf, and the C, N, P concentrations were lowest in litter. Leaf C：N：P ratios of tree, shrub, herb leaves and litter were 439.4:14.2:1, 599.2:13.5:1, 416.5:13.3:1, 504.8:15.5:1, respectively. The N：P ratios of tree, shrub and herb leaves were not significantly different, but they were all significantly higher than that of litter layer, indicating N：P ratio of different living life forms’ leaves was stable. Compared with N, C and P had better relationships in each layer, and the relationships of leaf C, N, P stoichiometry between tree and herb leaves were better than those between tree and shrub leaves. The correlations of C, N, P stoichiometry between litter and the tree or herb leaves were highly significantly positive, and the correlations of P stoichiometry between litter and shrub leaves were highly significantly positive. Shrub leaf N, P concentration increased with the increasing latitude, and herb leaf N, P concentrations decreased with the increasing longitude. Compared with the longitude and latitude, the effect of altitude was smaller, and only tree leaf N：P decreased with the increasing latitude. Multivariate linear regression analysis results showed that the influence of geographical factors on herb leaf was longitude > latitude > altitude, while was latitude > longitude >altitude for tree, shrub leaves and litter.

Effects of elevated O₃ on  leaf litter decomposition and nutrient release of Quercus mongolica in city.

SU Li-li, XU Sheng*, FU Wei, HE Xing-yuan, CHEN Wei, ZHAO Yi, PING Qin

2016, 27(2):  373-379. 

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The leaf litters of 10-year-old Quercus mongolica were put in nylon bags and exposed to elevated O₃  level (120 nmol·mol^-1) with the control of 40 nmol·mol-1 in open top chambers (OTCs) for 150 days to test the effect of high O₃ on the litter decomposition. The results showed that  no significant difference was observed in residual mass between elevated O₃ treatment and the control. Elevated O₃ inhibited the release of C and K during the decomposition, the residual rate of K under elevated O_3treatment (23.9%) was significantly higher than that of the control (17.1%) after 150day decomposition. Compared with the control, N mineralization and lignin degradation in elevated O₃ treatment were inhibited during early period of decomposition (0-60 d), but were promoted in later period (90-150 d). The changes of lignin/N showed no significant difference between elevated O₃ treatment and the control during the decomposition. Elevated O₃ generally promoted the release of P in leaf litter of Q. mongolica during the decomposition. C/P ratio was higher under elevated O₃ than that under control. Significant positive correlation was shown between residual dry mass of leaf litters and the residual rate of C, N, K, C/N ratio during decomposition. Elevated O₃ might play an important role in the nutrient cycle of forest ecosystem in highO₃ pollution area.

Tree uprooting of coniferousbroad leaved Korean pine mixed forest in Lesser Khingan Mountains, China.

GE Xiao-wen1, HOU Jie-jian1, WANG Li-hai1,2*, WANG Xing-long1, RONG Bin-bin1

2016, 27(2):  380-386. 

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The morphological parameters, root wad indexes and site conditions of 127 uprooting trees from 76 plots (20 m×20 m) in Lesser Khingan coniferousbroad leaved Korean pine mixed forest were measured. Then the influencing factors of uprooting differences and the relationship between uprooting trees and disturbed soil were analyzed. Results showed that the number of uprooting trees varied significantly among species. Abies nephrolepis suffered the most serious uprooting damage, then Pinus koraiensis, and Ulmus spp. the least. Deciduous species had a stronger uprootingresistant capacity than broadleaved species. With the increase of tree DBH and height, tree’s uprooting resistance declined rapidly first and then was gradually enhanced, and finally reached the minimum at diameter class of 20 cm and height class of 14 m, respectively. The smaller the taper degree and projected area of crown were, the stronger the uprooting resistance was. Uprooting rate was negatively correlated with stand density. Trees lying in wet ground, flat terrain, medium low altitude area and windward slope had a greater risk of uprooting. There were significant positive correlation between the depth, area and volume of disturbed soil and the DBH, height, volume of uprooting trees.

Spatial pattern analysis and associations of Quercus aquifolioides population at different growth stages in Southeast Tibet, China.

SHEN Zhi-qiang1, HUA Min2, DAN Qu1, LU Jie1*, FANG Jiang-ping1

2016, 27(2):  387-394. 

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This article analyzed the spatial pattern and its correlation of Quercus aquifolioides, Southeast Tibet at different growing stages by using Ripley’s L function in the method of point pattern analysis. The results showed the diameter structure of Q. aquifolioides population in Southeast Tibet followed a  ‘single peak’ shape and the saplings and medium trees predominated in number in the whole population. The population had a high regeneration rate and was of increase type. In the growth process of Q. aquifolioides from saplings to large trees, saplings and medium trees showed aggregation distribution at small scale, while large trees showed basically random distribution at whole scale. There was significant correlation between saplings with medium or large trees at small scale, however, there was no correlation between medium and large trees. In the growth process of Q. aquifolioides population from saplings, medium trees to large trees, its spatial pattern developed from aggregative distribution to random distribution. The natural regeneration of Q. aquifolioides population was affected not only by interspecific competition, but also by intraspecific competition. In the similar natural environment, the most important factors affecting the spatial pattern of Q. aquifolioides population were its own biological and ecological characteristics.

Seasonal dynamics of quantitative and morphological traits of poplar fine roots and their differences between successive rotation plantations.

WANG Yan-ping1,2, XU Tan3, ZHU Wan-rui1, WANG Qi-tong1, LIU Meng-ling1, WANG Hua-tian1,2*, LI Chuan-rong2, DONG Yu-feng4

2016, 27(2):  395-402. 

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Based on the fine root samples of the first and second generations of poplar (Populus ×euramericana ‘Neva’), this study examined the response of quantitative and morphological traits of fine roots of different orders and the difference between generations. The results showed that, the quantitative traits of fine roots, such as root length, root surface area and root biomass, presented obvious seasonal variation, and the fine root traits had obvious difference among root orders. The quantitative traits of lowerorder fine roots showed significant seasonal difference, and the fine root biomass increased in the growing season and then decreased significantly. The specific root length (SRL) of higherorder roots also showed significant change with season, while the root length density (RLD) and root tissue density (RTD) changed a little. The successive rotation resulted in the significant increase of root length, root biomass, SRL and RLD of 1-2 orders in the growing season. The quantitative traits of first order root significantly positively correlated with soil temperature and moisture, and significantly negatively correlated with the soil organic matter and soil available nitrogen content. However, the quantitative traits of second order root only showed significant correlation with soil nutrient content. The seasonal dynamics of poplar fine roots and the difference between successive rotation plantations implied carbon investment change of poplar to roots. Soil nutrient deficiency induced more carbon investment into roots, and this carbon allocation pattern might affect the aboveground productivity of poplar plantation.

Spatial distribution pattern of Populus euphratica and P. pruinosa clonal ramets in Tarim River Basin, China.

ZHAO Zheng-shuai1,2, ZHENG Ya-qiong1,2, LIANG Ji-ye1,2, HAN Zhan-jiang1,2, LI Zhi-jun1,2*

2016, 27(2):  403-411. 

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Spatial distribution pattern of Populus euphratica and P. pruinosa clonal ramets at three sites was studied, including natural mixed forest of P. euphratica and P. pruinosa in Awati County located in the downstream of Yarkant River, natural P. pruinosa forest in Group 16 of Nongyishi in the Tarim River upstream area, and natural P. euphratica forest in Luntai County located in the middle reach of the Tarim River. The clonal ramets of the three sites showed a cluster distribution pattern at eight sampling scales, i.e., 5 m×5 m, 5 m×10 m, 5 m×15 m, 10 m×10 m, 10 m×15 m, 15 m×15 m, 15 m×20 m, and 20 m×20 m. This pattern revealed that the cluster distribution was a basic property in the spatial distribution pattern of P. euphratica and P. pruinosa populations. At 5 m×5 m scale, negative binomial parameter  was minimum, while Cassie index, patchiness index  and aggregation strength were maximum for the two ramet populations at the three sites.

Parameter sensitivity of simulating net primary productivity of Larix olgensis forest based on BIOME-BGC model.

HE Li-hong1, WANG Hai-yan1*, LEI Xiang-dong2

2016, 27(2):  412-420. 

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Model based on vegetation ecophysiological process contains many parameters, and reasonable parameter values will greatly improve simulation ability. Sensitivity analysis, as an important method to screen out the sensitive parameters, can comprehensively analyze how model parameters affect the simulation results. In this paper, we conducted parameter sensitivity analysis of BIOME-BGC model with a case study of simulating net primary productivity (NPP) of Larix olgensis forest in Wangqing, Jilin Province. First, with the contrastive analysis between field measurement data and the simulation results, we tested the BIOME-BGC model’s capability of simulating the NPP of L. olgensis forest. Then, Morris and EFAST sensitivity methods were used to screen the sensitive parameters that had strong influence on NPP. On this basis, we also quantitatively estimated the sensitivity of the screened parameters, and calculated the global, the firstorder and the secondorder sensitivity indices. The results showed that the BIOME-BGC model could well simulate the NPP of L. olgensis forest in the sample plot. The Morris sensitivity method provided a reliable parameter sensitivity analysis result under the condition of a relatively small sample size. The EFAST sensitivity method could quantitatively measure the impact of simulation result of a single parameter as well as the interaction between the parameters in BIOME-BGC model. The influential sensitive parameters for L. olgensis forest NPP were new stem carbon to new leaf carbon allocation and leaf carbon to nitrogen ratio, the effect of their interaction was significantly greater than the other parameter’ interaction effect.

Response of phenophase to meteorological conditions and flowering forecast model on Amygdalus communis in Shache County, Xinjiang, China.

XU Xiang-ming1,2,GU Pin-qiang1*, CHEN Cong-min3, LI Zhong-xia3, FEI Lei1

2016, 27(2):  421-428. 

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Based on the phenophase data of Amygdalus communis and homochronous meteorological observation data at agrometeorological experimental station of Shache County during 2008-2013, the change characteristics of phenological period of A. communis and the effects of temperature and sunshine duration on them were analyzed. The results showed that before flowering, positive correlations existed among the first day of phenological phases, and after flowering, the correlations among the first day of phenological phases were mostly less. A significant positive correlation was observed between earlier bud flower swelling and the days of dormant period and growth period, and a significant negative correlation existed between later bud flower swelling and the days of dormant period and growth period. Before fruit maturation, there was negative correlation between temperature and the interval days of phenological period, and after fruit maturation, the correlations were mostly positive. But the correlation between sunshine duration and the interval days of phenological period was positive before and after fruit maturation. The interval days from fruit maturation to the beginning date of leaf colour change had evident response to the average maximum temperature, and the interval days from the emergence of inflorescence to the ending data of flowering, and from the beginning date of leaf colour change to the ending date of leaf fall, had obvious response to sunshine duration. When the dormant period exceeded 30 days and the average daily temperature met the rang from -3.0 to -7.5 ℃, A. communis would get into the flower swelling period after another 17-28 d. There were onetoone correspondences between flower swelling, the beginning date of flowering, the beginning date of leaf colour change, the ending date of leaf fall, and the first pentad average temperature greater than or equal to 4 ℃ and pentad average maximum temperature greater than or equal to 12 ℃, pentad average temperature greater than or equal to 14 ℃ and pentad average maximum temperature greater than or equal to 22 ℃ in spring, the first pentad temperature less than or equal to 10 ℃ and pentad average maximum temperature less than or equal to 18 ℃ in autumn, the first pentad average temperature less than or equal to 1.9 ℃ in winter, respectively. By using partial least squares regression analysis, the first day of  flowering forecast model of A. communis was established with good prediction.

Automated mapping of urban forests’ disturbance and recovery in Nanjing, China.

LYU Ying-ying1,2, ZHUANG Yi-lin1,2, REN Xin-yu1,2, LI Ming-shi1,2*, XU Wang-gu3, WANG Zhi3

2016, 27(2):  429-435. 

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Using Landsat TM/ETM⁺ dense time series observations spanning from 1987 to 2011, taking Laoshan forest farm and Purple Mountain as the research objects, the landsat ecosystem disturbance adaptive processing system (Ledaps) algorithm was used to generate surface reflectance datasets, which were fed to the vegetation change tracker model (VCT) model to derive urban forest disturbance and recovery products over Nanjing, followed by an intensive validation of the products. The results showed that there was a relatively high spatial agreement for forest disturbance products mapped by VCT, ranging from 65.4% to 95.0%. There was an apparent fluctuating forest disturbance and recovery rate over time, and the change trend of forest disturbance occurring at the two sites was roughly similar, but forest recovery was obviously different. Forest coverage in Purple Mountain was less than that in Laoshan forest farm, but the forest disturbance and recovery rates in Laoshan forest farm were larger than those in Purple Mountain.

Nitrogen fixation potential of biological soil crusts in Heidaigou open coal mine, Inner Mongolia, China.

ZHANG Peng1*, HUANG Lei1, HU Yi-gang1, ZHAO Yang1, WU Yong-chen2

2016, 27(2):  436-444. 

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Nitrogen limitation is common in terrestrial ecosystems, and it is particularly severe in damaged ecosystems in arid regions. Biological soil crusts (BSCs), as a crucial component of recovered vegetation, play a vital role in nitrogen fixation during the ecological restoration processes of damaged ecosystems in arid and semiarid regions. In this study, two dominant types of BSCs (i.e., cyanobacterialalgal crusts and moss crusts) that are widely distributed in the revegetated area of Heidaigou open pit coal mine were investigated. Samples were collected in the field and their nitrogenase activities (NA) were measured in the laboratory. The responses of NA to different hydrothermal factors and the relationships between NA and herbs in addition to crust coverage were analyzed. The results indicated that BSCs under reconstructed vegetation at different succession stages, abandoned land and natural vegetation showed values of NA ranging from 9 to 150 μmol C₂H₄·m^-2·h^-1, and the NA value of algae crust (77 μmol C₂H₄·m^-2·h^-1) was markedly higher than that of moss crust (17 μmol C₂H₄·m^-2·h^-1). In the revegetated area, cyanobacterialalgal crust and moss crust under shrubherb had higher NA values than those of crusts under arborshrub and arborshrubherb. The relationship between NA of the two BSCs and soil relative water content (10%-100%) as well as culture temperature (5-45 ℃) were of quadratic function. With elevated water content and cultural temperature, the NA values increased at the initial stage and then decreased, and reached the maximum value at 25 ℃ of cultural temperature and 60% or 80% of relative water content. The NA of cyanobacterialalgal crust had a significant quadratic function with herb coverage, as NA declined when herb coverage was higher than 20%. A significant negative correlation was observed between the NA of moss crusts and herb coverage. The NA values of the two types of BSCs had a significant positive correlation with crust coverage, since the NA was enhanced when the crust coverage was increased. We concluded that the different NA of the two BSCs in the re-vegetated area of Heidaigou open pit coal mine were caused by the composition of cryptograms. In addition, the differences of hydrothermal conditions and the composition of herb or crust coverage at different succession stages were also the contribution factors. Therefore, BSC construction and nitrogen fixation in re-vegetated areas is an important symbol for sustainable development in ecosystems.

Effects of supplemental irrigation by monitoring soil moisture on the waternitrogen utilization of wheat and soil NO₃^--N leaching.

SHI Yu, YU Zhen-wen*, HE Jian-ning, ZHANG Yong-li

2016, 27(2):  445-452. 

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Field experiments were conducted during 2012-2014 wheat growing seasons. With no irrigation in the whole stage (W₀) treatment as control, three supplemental irrigation treatments were designed based on average relative soil moisture contents at 0-140 cm layer, at jointing and anthesis stages (65% for treatment W₁; 70% for treatment W₂; 75% for treatment W₃; respectively), to examine effects of supplemental irrigation on nitrogen accumulation and translocation, grain yield, water use efficiency, and soil nitrate nitrogen leaching in wheat field. Soil water consumption amount, the percentage of soil water consumption and water irrigation to total water consumption in W₂ were higher, and soil water consumption of W₂ in 100-140 cm soil layer was also higher. The nitrogen accumulation before anthesis and after anthesis were presented as W₂, W₃＞W₁＞W₀, the nitrogen accumulation in vegetative organs at maturity as W₃＞W₂＞W₁＞W₀, and the nitrogen translocation from vegetative organs to grain and the nitrogen accumulation in grain at maturity as W₂＞W₃＞W₁＞W₀. At maturity,  soil NO₃^--N content in 0-60 cm soil layer was presented as W₀＞W₁＞W₂＞W₃, that in 80-140 cm soil layer was significantly higher in W₃  than in the other treatments, and no significant difference was found in 140-200 cm  soil layer among all treatments. W₂ treatment  obtained the highest grain yield, water use efficiency, nitrogen uptake efficiency and partial productivity of applied nitrogen. As far as grain yield, water use efficiency, nitrogen uptake efficiency and soil NO₃^--N leaching were concerned, the W₂ regime was the optimal irrigation treatment in this experiment.

Effects of increased planting density with reduced nitrogen fertilizer application on rice yield, N use efficiency and greenhouse gas emission in Northeast China.

ZHU Xiang-cheng1,2, ZHANG Zhen-ping3, ZHANG Jun2, DENG Ai-xing2, ZHANG Wei-jian2*

2016, 27(2):  453-461. 

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The traditional rice growing practice has to change to save resource and protect environment, and it’s necessary to develop new technology in rice cultivation. Therefore, a twoyear field experiment of Japonica rice (Liaoxing 1) was conducted in Northeast China in 2012 and 2013 to investigate the integrated effects of dense planting with less basal nitrogen (N) and unchanged topdressing N (IR)on rice yield, N use efficiency (NUE)and greenhouse gas emissions. Compared with traditional practice (CK), we increased the rice seedling density by 33.3% and reduced the basal N rate by 20%. The results showed that the average N agronomy efficiency and partial factor productivity were improved by 49.6% (P<0.05)and 20.4% (P<0.05), respectively, while the area and yieldscaled greenhouse gas emissions were reduced by 9.9% and 12.7% (P<0.05), respectively. Although IR cropping mode decreased panicle number and biomass production, it significantly enhanced rice seed setting rate and harvest index, resulting in an unchanged or even higher yield. NH₄⁺-N and NO₃^--N concentrations in rice rhizosphere soil were reduced, resulting in an increment of N recovery efficiency. Generally, proper dense planting with less basal N application could be a good approach for the tradeoff between rice yield, NUE and greenhouse gas emission.

Effects of cultural factors on yield of Linum usitatissimum (Tianya 9).

HE Li, ZHANG Jin, DU Yan-bin, CUI Tong-xia， WANG Li-jun*

2016, 27(2):  462-468. 

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Cultural factors influencing high yield and good quality Linum usitatissimum (Tianya 9) were investigated. The correlations between these factors and its yield were analyzed. Path coefficient and principal component analysis were conducted, adopting uniform design of the 8 cultivating factors, i.e. planting density (X₁), base nitrogen quantity (X₂), base phosphorus quantity (X₃), base potassium quantity (X₄), foliar fertilizer (potassium dihydrogen phosphate, X₅), foliar fertilizer (boron fertilizer, X₆), growth regulator (multieffect azole, X₇) and growth duration irrigation amount (X₈), aiming at exploring better cultivating plan of L. usitatissimum for Gansu Province. The results indicated that the factors influencing the yield of L. usitatissimum were X₁, X₇, X₂, X₃, X₅ and X₄ in a descending order. Simulation and optimization of the highest yield was further implemented. Frequency analysis showed that the cultivating factors resulting in yield higher than 173.58 kg·hm^-2 were 4.68-4.92 kg·hm^-2(X₁), 11.59-14.75 kg·hm^-2(X₂), 17.26-21.95 kg·hm^-2 (X₃), 7.00-12.50 kg·hm^-2(X₄), 1.41-1.81 kg·hm^-2(X₅) and 751.74-954.04 g·hm^-2(X₇).

Relationship between cellulose  synthesis metabolism and lodging resistance in intercropping soybean at seedling stage.

DENG Yu-chuan, LIU Wei-guo*, YUAN Xiao-qin, YUAN Jin, ZOU Jun-lin, DU jun-bo, YANG Wen-yu

2016, 27(2):  469-476. 

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Physical characteristics of stem are closely relative to the crop lodging. Increase of stem strength is conducive to resolve the problem of lodging. Three soybean cultivars with different shade tolerance were planted under maizesoybean intercropping and soybean monocropping, respectively. Physiological and biochemical indices including cellulose, soluble sugar, sucrose, starch contents and enzyme activity were investigated to assess the snapping resistance and lodging resistance of the stems of soybean seedling, and snapping and lodgingresistance indices were calculated for further verification. Furthermore, relationship analyses between these factors and the lodging of intercropped soybean showed that the intercropping soybean lodged seriously, the snapping resistance, lodging resistance index, contents of cellulose, soluble sugar, sucrose, starch and activities of the related enzymes were significantly lower than monocropping soybean at seedling stage. The three soybean cultivars showed different phenotypes in intercropping condition. The snappingresistant Nandou12 with strong shadetolerant traits was the most lodgingresistant phenotype, and it also harbored high contents of cellulose, soluble sugar, sucrose, starch and active enzymes. The lodging resistance index, cellulose content of the stems of intercropped soybean seedling were significantly positively correlated with the snapping resistance, and were significantly negatively correlated with the actual lodging percentage. The activities of sucrose phosphate synthase (SPS), sucrose synthase(SS) and neutral invertase (NI) were positively correlated with sucrose is content, but not  the acid invertase (AI). The activities of SPS, NI and SS were positively correlated with cellulose content, but not  AI. In a word, the high activities of SPS and SS in the soybean stem were the enzymatic basis to maintain relatively higher cellulose and sucrose content, which is conducive to improve the stem strength and enhance the lodging resistance ability in intercropping condition. Effects of different light conditions on cellulose metabolic mechanism of soybean seedling stems, lodging resistant characteristics of soybean seedlings studied in the cornsoybean intercropping system provided a basis  for screening more shadetolerant soybean variety.

Effects of cold-shock on the growth and flower bud differentiation of tomato seedlings under high temperature stress.

LI Sheng-li1*, XIA Ya-zhen2, SUN Zhi-qiang1

2016, 27(2):  477-483. 

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In order to explore the effects of cold-shock on the growth and flower bud differentiation of tomato seedlings under high temperature, tomato seedlings were subjected to coldshock treatments every day with 10 ℃  for 10 minutes in an artificial climate chamber. Tomato seedlings were treated with cold-shock at the first true leaf stage and the treatment lasted for 15 days. Tomato seedlings without cold-shock were used as control. At the fourth true leaf period of tomato seedlings, five plants were randomly sampled and the growth characteristics and the ultrastructure changes of mesophyll cell of tomato seedlings were examined. The flower bud differentiation process of tomato seedlings was observed at the periods of the second, fourth and sixth true leaves respectively. Flowering and fruiting of tomato seedlings were also investigated after transplanting. The results showed that the stem diameter and health index of tomato seedlings with cold-shock were enhanced by 7.2% and 55.5% compared with seedlings without cold-shock. Mesophyll cells of the seedlings with cold-shock arranged loosely and various organelles such as chloroplasts and mitochondria were morphologically integrated, while chloroplasts and mitochondria of seedlings mesophyll cells without cold-shock swelled up and thylakoids vacuolized apparently. The flower bud differentiation process of seedlings with cold-shock could be advanced significantly at the early seedling stage compared with the control and the advancement was weakened with the seedling growing. Fruit set number and percentage on the first and second inflorescence of tomato plants transplanted by seedlings with cold-shock were enhanced significantly compared with those of the control. These results indicated that the injury of membrane structure of various organelles, especially chloroplast and mitochondria could be alleviated by cold-shock treatment under high temperature tress. Cold-shock treatment could not only improve the seedling growth under high temperature stress, but also advance the process of early flower bud differentiation and improve the fruit set.

Effects of interaction between vermicompost and probiotics on soil property, yield and quality of tomato.

SHEN Fei1,2, ZHU Tong-bin3, TENG Ming-jiao1, CHEN Yue1, LIU Man-qiang1,2, HU Feng1, LI Hui-xin1,2*

2016, 27(2):  484-490. 

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In this study, we investigated the effects of two strains of probiotic bacteria (Bacillus megaterium BM and Bacillus amyloliquefaciens BA) combined with chemical fertilizers and vermicompost on the soil property, the yield and quality of tomato. The results showed that under the same nutrient level, vermicompost significantly increased the yield, soluble sugar and protein contents of fruit, the soil pH and available phosphorus when compared with chemical fertilizers. Vermicompost combined with probiotics not only increased the tomato yield, soluble sugar, protein and vitamin C contents, sugar/acid ratio of fruit, and reduced the organic acid and nitrate nitrogen contents of fruit, also increased the soil pH and nitrate nitrogen content, and reduced soil electric conductivity  when compared with vermicompost treatment. This improved efficiency was better than that by chemical fertilizers combined with probiotics. For BA and BM applied with chemical fertilizers or vermicompost, both stains had no significant effect on tomato quality. When coapplied with vermicompost, BA and BM showed significant difference in tomato yield. High soil available phosphorus content was determined when BM was combined with chemical fertilizers, while high soil available potassium content was obtained when BA was combined with vermicompost. Our results suggested that probiotics and vermicompost could be used as alternatives of chemical fertilizers in tomato production and soil fertility improvement.

Effects of exogenous spermidine on mitochondrial function of tomato seedling roots under salinity alkalinity stress.

PAN Xiong-bo1,2, XIANG Li-xia1,2, HU Xiao-hui1,2*, REN Wen-qi1,2, ZHANG Li1,2, NI Xin-xin1

2016, 27(2):  491-498. 

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Two cultivars of tomato (Solanum lycopersicum, cvs. ‘Jinpengchaoguan’ and ‘Zhongza No. 9’, with the former being more tolerant to salinealkaline stress) seedlings grown hydroponically were subjected to salinityalkalinity stress condition (NaCl:Na₂SO₄:NaHCO₃:Na₂CO₃=1:9:9:1) without or with foliar application of 0.25 mmol·L^-1spermidine (Spd), and the root morphology and physiological characteristics of mitochondrial membrane were analyzed 8 days after treatment, to explore the protective effects of exogenous Spd on mitochondrial function in tomato roots under salinityalkalinity stress. The results showed that the salinityalkalinity stress increased the concentrations of both mitochondrial H₂O₂ and MDA as well as the mitochondrial membrane permeability in the roots of the two cultivars, while it decreased the mitochondrial membrane fluidity, membrane potential, Cyt c/a and H⁺-ATPase activity, which impaired the mitochondria and therefore inhibited the root growth; and these effects were more obvious in ‘Zhongza No. 9’ than in ‘Jinpengechaoguan’. Under the salinityalkalinity stress, foliar application Spd could effectively decrease the concentrations of mitochondrial H₂O₂ and MDA and mitochondrial membrane permeability, while increased the mitochondrial membrane fluidity, membrane potential, Cyt c/a and H⁺-ATPase activity. These results suggested that exogenous Spd could effectively mitigate the damage on mitochondria induced by salinityalkalinity stress, and the alleviation effect was more obvious in ‘Zhongza No. 9’ than in ‘Jinpengchaoguan’.

Effects of Acaulospora spinosa on plant growth and lycopene related genes (psy1 and psy2) expression of tomato.

LI Ke1, XU Jian-jun2, WANG Lu-yao1, WANG Chu-nan1,YU Chen1, GUO Jian-hua1*

2016, 27(2):  499-503. 

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In the present study, an arbuscular mycorrhizal fungus (AMF) strain Acaulospora spinosa XJ27, previously isolated from tomato root rhizosphere in Xinjiang’s suburbs, was used to inoculate root systems of tomato cultivar “MicroTom”. The biomass, contents of chlorophyll in leaves and lycopene in fruits of plants between the treatments with and without XJ27 were analyzed, and the expression level of lycopene biosynthesis relevant genes (psy1 and psy2) investigated by semi quantitativePCR and realtime PCR. The results indicated that the application of XJ27 to the rhizosphere of tomato increased the biomass and yield of the treated plants, the expression of psy1 and psy2 was improved, and the amount of lycopene accumulation in tomato. It suggested Acaulospora spinosa XJ27 has a great potential in utilization.

Effects of inter-row economic crop planting on soil moisture in a rain-fed jujube orchard in loess hilly region, China.

LING Qiang1,2, ZHAO Xi-ning2,3*, GAO Xiao-dong2,3, LI Lu-sheng1, LI Hong-chen1, SUN Wen-hao1

2016, 27(2):  504-510. 

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Soil moisture variation in dryland sloping jujube orchard was investigated after introducing two economic crops, i.e., feed Brassica napus (JR) and Hemerocallis fulva (JH) planted between jujube rows. Jujube tree without interrow crop was set as control (CK). The results showed that mean soil moisture for JR and JH in the 0-180 cm soil layer increased by  6.2% and 10.1% compared with CK, respectively. Soil moisture changed mainly in the 0-60 cm soil layer in growth stage of Jujube trees. Soil moisture in JR and JH treatments significantly increased in the 0-60 cm soil layer, which could meet the demand in water resource of jujube plantation. The water consumption of jujube trees also mainly concentrated in the 0-60 cm soil layer. There was a significant decay exponential relationship between the soil moisture in the 0-20 cm layer and the drought duration after rainfall. During the 18-day dry period after rain, the soil moisture contents of JR and JH were apparently higher than that of CK. In conclusion, the jujubecrop intercropping system improved the soil moisture condition. It was an effective measure to overcome the seasonal drought in jujube orchards on the loess hilly region.

Effects of phosphorus fertilization on biomass accumulation and phosphorus use efficiency of trelliscultivated melon.

CHEN Bo-lang*, WU Hai-hua, LUO Jia, HAO Li-na, QI Xiao-chen, ZHAO Ku

2016, 27(2):  511-518. 

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A field experiment applying six rates of P fertilizer (P₂O₅ 0, 150, 225, 300, 375 and 450 kg·hm^-2, respectively) was conducted to investigate the effects of P fertilization on dry matter accumulation (DMA)〖KG-*4〗, P uptake and accumulation (PUA) and P use efficiency (PUE) of trelliscultivated melon. Results showed that, P application increased DMA and PUA,  for 150 and 225 kg P₂O₅·hm^-2 treatments, being 19.9% and 26.3%, 23.0% and 26.3% higher than that in no P fertilizer treatment at fruiting stage. With plant growth, DMA and PUA of different organs and the whole plant gradually increased. DMA and PUA were mainly distributed in the leaves during the early stage of the growth and in the fruit during the latter stage. P application decreased the recovery efficiency of applied P (RE_P), agronomic efficiency of applied P (AE_P) and partial factor productivity of applied P (PF_P). At 150 kg·hm^-2 P application rate, the maximum RE_P, AE_P and PF_P were 11.1%, 152.9 kg·kg^-1 and 476.3 kg·kg^-1, respectively. Compared with no P fertilizer treatment, melon yields of 150 and 225 kg P₂O₅·hm^-2 treatments increased by 47.3% and 39.7%, respectively. In summary, the vining stage and fruit expanding stage were the key periods for P application in trelliscultivated melon system. Based on synthesized economic yield and P fertilizer efficiency, the recommendation of P fertilizer for trelliscultivated melon is 150-225 kg P₂O₅·hm^-2under the climatic condition of the experimental area.

Effects of exogenous melatonin on nitrogen metabolism and osmotic adjustment substances of melon seedlings under sub-low temperature.

GAO Qing-hai*, JIA Shuang-shuang, MIAO Yong-mei, LU Xiao-min, LI Hui-min

2016, 27(2):  519-524. 

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The melon cultivar ‘Yangjiaosu’ was subjected to the treatment of 18 ℃/12 ℃ (day/night) in an artificial climate chamber for 6 days, and the activities of nitrogen metabolism related enzymes \[nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT) and glutamate dehydrogenase (GDH)\], the contents of total N, NO₃^--N and NH₄⁺-N as well as the osmotic adjustment substances of melon leaf were then determined. The results showed that, compared with the control, sublow temperature treatment reduced the contents of total N, NO₃^--N and the NR activity, but increased the content of NH₄⁺-N, thereby leading to the growth inhibition of melon. Exogenous MT treatment significantly improved the activities of nitrogen metabolism related enzymes, especially the activities of GS and GOGAT, effectively reducing the content of NH₄⁺-N. Moreover, MT treatment increased the contents of proline, soluble protein and soluble sugar, and alleviated the damage of sublow temperature on the cell membrane by reducing the relative electrical conductivity and MDA content of melon leaves. In short, this work suggested that exogenous MT would enhance the sublow temperature adaptability of melon by decreasing the leaf content of NH₄⁺-N, increasing the contents of osmotic adjustment substances and reducing the membrane lipid peroxidation levels.

Hyperspectral parameters and prediction model of soil moisture in coastal saline.

LI Chen1, ZHANG Guo-wei2, ZHOU Zhi-guo1, ZHAO Wen-qing1, MENG Ya-li1, CHEN Bing-lin1, WANG You-hua1

2016, 27(2):  525-531. 

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Based on the data of soil moisture content and indoor soil surface spectral reflectance from five sampling sites of coastal saline soil, this paper analyzed the relationship between soil moisture content and soil spectrum in wavelength 350-2500 nm. We determined spectral parameters under ratio spectral index (RSI), normalized difference spectral index (NDSI) and difference spectral index (DI), and established the quantitative model of soil moisture content. The results showed significant negative correlation between spectral reflectance and soil moisture content, and the maximum negative correlation was near 1930 nm (r=0.86). By comparison of the regression equation of RSI, NDSI and DI, it was found that the regression equation of exponential function (y=0.00001e^9.72053x) built by soil moisture content based on RSI (R₁₄₀₇,R₁₄₅₉) presented the maximum R₂(0.780) and the minimum SE (0.016). The established model based on RSI (R₁₄₀₇, R₁₄₅₉) could be used to monitor soil moisture content accurately in Jiangsu coastal saline soils.

Distribution of soil organic carbon in surface soil along a precipitation gradient in loess hilly area.

SUN Long1,2, ZHANG Guang-hui1,3*, LUAN Li-li3, LI Zhen-wei4, GENG Ren3

2016, 27(2):  532-538. 

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Along the 368-591 mm precipitation gradient, 7 survey sites, i.e. a total 63 investigated plots were selected. At each sites, woodland, grassland, and cropland with similar restoration age were selected to investigate soil organic carbon distribution in surface soil (0-30 cm), and the influence of factors, e.g. climate, soil depth, and land uses, on soil organic carbon distribution were analyzed. The result showed that, along the precipitation gradient, the grassland (8.70 g·kg^-1) > woodland (7.88 g·kg^-1) > farmland (7.73 g·kg^-1) in concentration and the grassland (20.28 kg·m^-2) > farmland (19.34 kg·m^-2) > woodland (17.14 kg·m^-2) in density. The differences of soil organic carbon concentration of three land uses were not significant. Further analysis of pooled data of three land uses showed that the surface soil organic carbon concentration differed significantly at different precipitation levels (P<0.001). Significant positive relationship was detected between mean annual precipitation and soil organic carbon concentration (r=0.838, P<0.001) in the  of pooled data. From south to north (start from northernmost Ordos), i.e. along the 368-591 mm precipitation gradient, the soil organic carbon increased with annual precipitation 0.04 g·kg^-1·mm^-1,  density 0.08 kg·m^-2·mm^-1. The soil organic carbon distribution was predicted with mean annual precipitation, soil clay content, plant litter in woodland, and root density in farmland.

Modelling the changes of soil organic carbon under different management practices using Daycent model in North China.

ZHANG Xuan1,2,3, XIE Li-yong2, GUO Li-ping1*, FAN Jing-wei1

2016, 27(2):  539-548. 

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The Daycent model was calibrated and validated using measured crop yield and soil organic carbon (SOC) as double assessment standards based on the experimental data from three longterm experiments (i.e. Zhengzhou site in Henan Province, Yucheng site in Shandong Province and Quzhou site in Hebei Province) in North China. Results showed that the buildup parameters simulated the longterm dynamic changes of crop yields and SOC very well, indicating Daycent model could project the dynamic changes of crop yield and SOC soundly. After calibration and validation, Daycent model was used to simulate the changes of SOC under future climate scenarios (representative concentration pathway 4.5, RCP 4.5) with four different management practices (chemical fertilizer, NPK; chemical fertilizer+organic manure, MNPK; straw incorporation, SNPK; notillage+straw incorporation, NT) at the three sites. At Zhengzhou site, the change of SOC was highest for MNPK treatment during the period of 2001-2050 (1.7%) and followed by SNPK (1.3%) and NPK (0.8%) in terms of annual relative increase rate (ARIR), indicating long-term amendment of organic manure could effectively increase SOC for light loam soil with irrigation condition. At Yucheng site, the increase of SOC (ARIR) under MNPK treatment (0.4%) was higher than under NPK treatment (0.3%). In addition, the increase of SOC was very low under all treatments at this site, probably due to light soil salinization. At Quzhou site, the increase of SOC (ARIR) under NT treatment was 1.3%, higher than those under SNPK treatment (0.7%) and NPK treatment (0.4%), indicating NT was more effective for SOC increase in this area. We concluded that notillage with straw incorporation is the optimized management practice to increase SOC in North China Plain due to mild climate, sound irrigation and available mechanical equipment for straw processing and notillage operation.

Spatial distribution of soil total nitrogen in Liangshui National Nature Reserve based on local model.

ZHEN Zhen1, GUO Zhi-ying2, ZHAO Ying-hui1, LI Feng-ri1*, WEI Qing-bin3

2016, 27(2):  549-558. 

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Based on LiDAR data of Liangshui National Nature Reserve, digital elevation model (DEM) was constructed and both primary terrain attributes (slope, aspect, profile curvature, etc.) and secondary terrain attributes (wetness index, sediment transport index, relative stream power index, etc.) were extracted. According to the theory of soil formation, geographically weighted regression (GWR) was applied to predict soil total nitrogen (TN) of the area, and the predicted results were compared with those of three traditional interpolation methods including inverse distance weighting (IDW), ordinary Kriging (OK) and universal Kriging (UK). Results showed that the prediction accuracy of GWR (77.4%) was higher than that of other three interpolation methods and the accuracy of IDW (69.4%) was higher than that of OK (63.5%) and UK (60.6%). The average of TN predicted by GWR reached 4.82 g·kg^-1 in the study area and TN tended to be higher in the region with higher elevation, bigger wetness index and stronger relative stream power index than in other areas. Further, TN also varied partly with various aspects and slopes. Thus, local model using terrain attributes as independent variables was effective in predicting soil attribute distribution.

Assessment on the yield loss risk of longan caused by cold damage in South China.

ZHAO Jun-fang1, YU Hui-kang2

2016, 27(2):  559-566. 

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Using daily climate variables gathered from 64 meteorological stations in South China from 1961 to 2012, recognized hazard indicators about disaster grades of cold damage for longan, and methods on agricultural meteorological disasters risk and simulation technology, the yield loss risks of longan caused by cold damage in South China during different developmental periods were assessed. The results showed that during the period of physiologic differentiation of flower bud, the disasters of longan affected by mild cold damage in South China were the most common, followed by severe cold damage and moderate cold damage. The hazards caused by cold damage under different grades varied. In particular, under mild cold damage, light disaster of longan was found in Fujian, followed by Guangdong and Hainan, and Guangxi was serious. Under moderate cold damage, light disaster of longan was found in Hainan, followed by Guangdong and Guangxi, and Fujian was serious. Under severe cold damage, light disaster of longan was found in Hainan, followed by Guangdong and Guangxi, Fujian was serious. During the period of morphologic differentiation of flower bud, the disasters of longan affected by mild cold damage in South China were the most common, followed by severe cold damage and moderate cold damage, while the disasters of longan under mild, moderate and severe cold damages within this period were similar. Specifically, light disasters of longan were all found in Hainan, followed by Guangdong, Guangxi and Fujian. During the period of dormancy, the disaster of longan affected by mild cold damage in South China was the most common, followed by severe cold damage and moderate cold damage. Under mild and severe cold damage, light disaster of longan was found in Fujian, followed by Guangdong and Hainan, and Guangxi was serious. However, under moderate cold damage, light disaster of longan was found in Hainan and Guangxi, followed by Guangdong, and Fujian was serious. At the same level of hazard, the largest risk indices of yield loss of longan during different developmental stages significantly differed. Under mild cold damage, serious disasters of longan were found in the period of physiologic differentiation of flower bud, followed by the period of morphologic differentiation of flower bud and the period of dormancy. However, under moderate and severe cold damage, serious disasters of longan were found in the period of physiologic differentiation of flower bud, followed by the period of dormancy and the period of morphologic differentiation of flower bud.

Comprehensive evaluation of improving effects of different organic wastes on a newly reclaimed cultivated land.

XU Qiu-tong1, KONG Zhang-liang2, ZHANG Ming-kui1*

2016, 27(2):  567-576. 

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There are many problems such as low soil organic matter, available nutrients and microbial activity, compaction, and poor tillage properties for a newly reclaimed cultivated land, and the establishment of a fast, effective measure for improving soil fertility quality is of importance to enhance the quality and production performance of the newly cultivated land. A field experiment was carried out to observe the effect of organic wastes on soil fertility of a newly reclaimed cultivated land, and compared the differences of different types of urban organic wastes. The field experiment included nine treatments, i.e., pig manure, chicken manure, rice straw, vegetable harvest residue, urban sludge, biogas residue, manure+rice straw compost,  garbage compost and control without organic fertilizer at annual application rate of 30 t·hm^-2, and ran for three consecutive years. The results showed that the application of each type of the eight organic wastes had obvious effects on improving soil fertility. Among them, pig manure, chicken manure, pig manure+rice straw compost, rice straw and biogas residue were the most effective to enhance the carbon pool management index of soil. The addition of pig manure+rice straw compost and biogas residue had the best effect on increasing the soil water stable aggregates and decreasing soil bulk density. Sewage sludge, pig manure+rice straw compost and garbage compost could enhance soil water holding capacity. Pig manure, chicken manure and pig manure+rice straw compost had most obvious effect on increasing soil available nutrients. All kinds of organic wastes increased the number of soil microorganisms and the activity of enzymes. There were some risk of soil heavy metals pollution for the longterm application of sludge, garbage compost and manure. However, the impact of shortterm application of the wastes on soil environmental quality was not obvious. Overall, effects of organic wastes on soil fertility decreased in the order of pig manure+rice straw compost>chicken manure>pig manure>biogas residue>garbage compost>rice straw>urban sludge>vegetable harvest residue, and the effects on soil pollution increased in the sequence of rice straw<vegetable harvest residue<pig manure+rice straw compost<biogas residue<chicken manure<pig manure<garbage compost<urban sludge.

Carbon emissions and low-carbon regulation countermeasures of land use change in the city and town concentrated area of central Liaoning Province, China.

XI Feng-ming1,2*, LIANG Wen-juan1,2, NIU Ming-fen2, WANG Jiao-yue1 

2016, 27(2):  577-584. 

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Carbon emissions due to land use change have an important impact on global climate change. Adjustment of regional land use patterns has a great scientific significance to adaptation to a changing climate. Based on carbon emission/absorption parameters suitable for Liaoning Province, this paper estimated the carbon emission of land use change in the city and town concentrated area of central Liaoning Province. The results showed that the carbon emission and absorption were separately 308.51 Tg C and 11.64 Tg C from 1997 to 2010. It meant 3.8% of carbon emission was offset by carbon absorption. Among the 296.87 Tg C net carbon emission of land use change, carbon emission of remaining land use type was 182.24 Tg C, accounting for 61.4% of the net carbon emission, while the carbon emission of land use transformation was 114.63 Tg C, occupying the rest 38.6% of net carbon emission. Through quantifying the mapping relationship between land use change and carbon emission, it was shown that during 1997-2004 the contributions of remaining construction land (40.9%) and cropland transform ation to construction land (40.6%) to carbon emission were larger, but the greater contributions to carbon absorption came from cropland transformation to forest land (38.6%) and remaining forest land (37.5%). During 2004-2010, the land use types for carbon emission and absorption were the same to the period of 1997-2004, but the contribution of remaining construction land to carbon emission increased to 80.6%, and the contribution of remaining forest land to carbon absorption increased to 71.7%. Based on the carbon emission intensity in different land use types, we put forward the lowcarbon regulation countermeasures of land use in two aspects. In carbon emission reduction, we should strict control land transformation to construction land, increase the energy efficiency of construction land, and avoid excessive development of forest land and water. In carbon sink increase, we should improve forest coverage rate, implement cropland, grassland transform to forest land, strengthen forest land and water protection, and adjust cropland internal structure and scientifically implement cropland management.

Effects of Phyllostachys edulis invasion of native broadleaf forest on soil fungal community.

LI Yong-chun, LIANG Xue, LI Yong-fu, WANG Qi, CHEN Jun-hui, XU Qiu-fang*

2016, 27(2):  585-592. 

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To investigate variation of soil fungal community in response to invasion of Phyllostachys edulis into native broadleaf forest, we characterized the community structure and the abundance of fungi in soil under bamboo (BB), mixture forest of bamboo and broadleaf (MF) and broadleaf forest (BL) using terminal restriction fragment length polymorphism (T-RFLP) and realtime quantitative PCR. The results showed that the most obvious difference in the soil fungal community structure was observed between the BB and BF stands, followed by that between the MF and BL. Shannon index and evenness index of soil fungi were higher in the MF than in the BB and BL. pH and NH₄⁺-N content were the most important environmental gradients on the distribution of fungal community under BB, while NO₃^--N content significantly affected the distribution of the fungal community under BL. The abundance of fungi in BL was significantly higher than that in BB and MF, and the fungi abundance showed a negative correlation with soil pH but a positive correlation with NO₃^--N content. These results implied that heterotrophic nitrification driven by fungi could occur in soil of BL, and this process might be changed by the bamboo invasion.

Distribution and bioavailability of seven heavy metals in mangrove wetland sediments in Dongzhai Harbor, Hainan Island, China.

JI Yi-nuo, ZHAO Zhi-zhong*, WU Dan, FU Xiao-nuo

2016, 27(2):  593-600. 

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In this study, total and available contents of seven typical heavy metals (Cr, Ni, Cu, Zn, As, Cd and Pb) were determined in mangrove wetland sediments in Dongzhai Harbor, and the distribution characteristics and bioavailability of these heavy metals in sediment were analyzed. The results showed that all the metals contents in this area were higher than in mangrove wetlands in Yalong Bay and Sanya Bay, but lower than the average level in mangrove wetlands in South China and other areas in the world, which was at a moderate to low level. The contents of heavy metals in surface layer of sediment significantly differed among barren shoal, the edge and inside of forest. All the metals were obviously accompanyingly deposited in the  columnar sediments, which indicated a strong homogeneous source. The available contents of seven heavy metals in the surface sediments were extracted by EDTA, which had the order of Cu>Cr>Zn>Ni>As>Pb>Cd. All the maximum ratios of available to total content of elements appeared in surface or middle to upper layers, except Ni. There was significant positive correlation between available and total contents of target metals.

Meta-analysis of stable carbon and nitrogen isotopic enrichment factors for aquatic animals.

GUO Liang, SUN Cui-ping, REN Wei-zheng, ZHANG Jian, TANG Jian-jun, HU Liang-liang*, CHEN Xin

2016, 27(2):  601-610. 

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Isotopic enrichment factor (Δ, the difference between the δ value of food and a consumer tissue) is an important parameter in using stable isotope analysis (SIA) to reconstruct diets, characterize trophic relationships, elucidate patterns of resource allocation, and construct food webs. Isotopic enrichment factor has been considered as a constancy value across a broad range of animals. However, recent studies showed that the isotopic enrichment factor differed among various types of animals although the magnitude of variation was not clear. Here, we conducted a metaanalysis to synthesize and compare Δ^13C and Δ¹⁵N among four types of aquatic animals (teleosts, crustaceans, reptiles and molluscs). We searched for papers published before 2014 on Web of Science  and CNKI  using the key words “stable isotope or isotopic fractionation or fractionation factor or isotopic enrichment or trophic enrichment”. Fortytwo publications that contain 140 studies on Δ¹³C and 159 studies on Δ¹⁵N were obtained. We conducted three parallel metaanalyses by using three types of weights (the reciprocal of variance as weights, the sample size as weights, and equal weights). The results showed that no significant difference in Δ¹³C among different animal types (teleosts 1.0‰, crustaceans 1.3‰, reptiles 0.5‰, and molluscs 1.5‰), while Δ¹⁵N values were significantly different (teleosts 2.4‰, crustaceans 3.6‰, reptiles 1.0‰ and molluscs 2.5‰).Our results suggested that the overall mean of Δ¹³C could be used as a general enrichment factor, but Δ¹⁵N should be chosen according to the type of aquatic animals in using SIA to analyze trophic relationships, patterns of resource allocation and food webs.

Intestinal bacterial community is indicative for the healthy status of  Litopenaeus vannamei.

WU Jin-feng1, XIONG Jin-bo1,2, WANG Xin3, QIU Qian-ling-lin1, ZHENG Jia-lai1, ZHANG De-min1,2*

2016, 27(2):  611-621. 

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High density and intensive Litopenaeus vannamei aquaculture has increased the frequency of shrimp disease, however, it remains uncertain whether change in intestinal bacteria could be indicative of shrimp health state (healthy or diseased). Therefore, we collected water and shrimp intestine samples from ponds with or without diseased shrimps. Using bacterial 16S rRNA gene as a biomarker, the bacterial community structure and diversity were evaluated with the Illumina MiSeq sequencing technique. The results showed that the variations of bacterioplankton community were primarily shaped by the levels of NO₂^--N, chlorophyll a and PO₄^3--P. Bacterial diversity was significantly lower in diseased shrimps than in healthy ones. Using a response ratio analysis, we screened 28 operational taxonomic units (OTUs), and their abundances significantly changed in the intestines between healthy and diseased shrimps. In general, the abundances of OTUs belonged to Actinobacteria, Flavobacteria and Bacilli significantly decreased in diseased shrimps compared with those in healthy shrimps, while the OTUs affiliated to Clostridia showed an opposite pattern. In addition, we obtained 61 indicator species that primarily affiliated to Bacteroidetes, Proteobacteria, Firmicutes, Planctomycetes and Actinobacteria. Notably, the identified indicator taxa exhibited clearly discriminative patterns among habitats (water or intestine) and health status. Collectively, this study provided scientific information for development of new probiotics and disease prevention.

Demographic analysis of the blue shark, Prionace glauca, in the North Atlantic Ocean.

GAO Chun-xia1,2,3,4,5, DAI Xiao-jie1,2,3,4,5, TIAN Si-quan1,2,3,4,5*, WU Feng1,2,3,4,5, ZHU Jiang-feng1,2,3,4,5

2016, 27(2):  622-628. 

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The blue shark, Prionace glauca, is the main bycatch species in tuna longline fishery. As one of top species in the oceanic food webs, the blue shark plays an important role in the marine ecosystem. Traditional stock assessment methods are difficult to accurately evaluate the population dynamic for this shark because of limited data. Based on lifehistory parameters of the blue shark in the North Atlantic, demographic analysis was employed to estimate the demographic parameters and evaluate the potential exploitation for the blue shark. Moreover, we discussed the relationship between age at first capture and critical value of fishing mortality corresponding to the value of intrinsic rate of natural increase 0. The results showed that the survival rate (S) of blue shark from 0.719 to 0.820, intrinsic rate of natural increase (r₀) from 0.250 to 0.381, time of population doubling (t_x2) from 1.819 to 2.773 years, reproduction rate per generation (R₀) from 6.600 to 22.255, and generation time (G) from 8.498 to 10.162 years. The sensitivity analysis for the life history parameters revealed that the uncertainties of natural mortality existed in the first age class, age at maturity and maximum age had slight influence on the demographic parameters. Fishing mortality (F_c) increased with the age at first capture. When the age at first capture (t_c) was more than five, there was no obvious relationship between F_c and t_c.

Influence of low temperature and photoperiod on the substances in Locusta  migratoria tibetensis.

ZHU Yu-han1, LI Qing1*, YANG Gang2, BAIMA Tun-zhu2, KUANG Jian-kang2, JIANG Chun-xian1, WANG Hai-jian1, YANG Qun-fang1

2016, 27(2):  629-633. 

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In order to investigate the adaption of Locusta migratoria tibetensis to the environment, this paper adopted the experiments with full light exposure (24L/0D), total darkness  (0L/24D), and low temperature (5 ℃) to study the effects of low temperature and illumination stress on the coldresistant substances of L. migratoria tibetensis. The results showed that the fat content of L. migratoria tibetensis reached 11.8%, which was the  highest under the condition of full light exposure (24L/0D) without low temperature stress. The fat content of body in low temperature and darkness treatment (0L/24D) was 4.7%, which was the lowest. The trehalose, mannitol and sorbitol contents of locust after low temperature stress were significantly higher than that of locust without the same stress. Glycogen content of locust treated by full light exposure without low temperature stress was the highest (6.40 mg·g^-1). Besides, low temperature and darkness treatment stimulated the accumulation of alanine, glutamic acid, lysine, and phenylalanine, benefiting the accumulation of multiamino acids, glycerinum, micromolecule carbohydrate, and the reduction of glycogen and fat content.

Distribution and environmental function of glomalin-related soil protein: A review.

WANG Jian, ZHOU Zi-yan, LING Wan-ting*

2016, 27(2):  634-642. 

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Glomalin-related soil protein (GRSP), a glycoprotein secreted by arbuscular mycorrhizal fungi (AMF), is abundant in soil. GRSP can be fractionated into total glomalinrelated soil protein (TG), easily extracted glomalinrelated soil protein (EEG), immunoreactive total glomalin (IRTG) and immunoreactive easily extracted glomalin (IREEG). The content of GRSP in soil differed with different soil use type, fertilization condition, AMF and host plant species, and environmental conditions. GRSP significantly positively correlates to the aggregate water stability. GRSP may reduce the release of CO₂ in agroecosystem, benefit the soil carbon fixation, and reduce the bioavailability and plant toxicity of heavy metals in soil. The extraction and characterization of GRSP are of great importance to understanding the basic behaviors of GRSP in soil environments. Further studies are needed to clarify the molecular biology function of GRSP in agro-ecosystem based on the knowledge of proteins and related genes, and impacts of GRSP on the environmental behavior of organic pollutants in soil.

Eco-physiology and regulation of leaf senescence and maturity performance in cotton: A review.

CHEN Yi-zhen1,2, DONG He-zhong1*

2016, 27(2):  643-651. 

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Senescence is a natural termination process at the plant or organ level of cotton, leading to the inevitable end of the growth and development process. Maturity performance is termed as senescence performance and results of a cotton plant during boll opening, including normal maturity, premature senescence and latematurity in cotton. Senescence and maturity performance are influenced by genotype and environment interactions. This paper summarized and reviewed the research progress in ecophysiology and molecular biology of cotton leaf senescence. Strategies were proposed to regulate cotton growth and aging through breeding of stablydeveloped varieties, rational application of plant growth regulators and agronomic cultivation measures, to realize normal maturity and improve yield and quality of cotton.

Ecological benefits  of the hedgerows: A review.

CHEN Die1,2, WEI Wei1*

2016, 27(2):  652-662. 

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The hedgerows, also called vegetative barriers, are defined as strips of grass, trees or shrubs or combinations of herbaceous and woody plants established along the contour lines of slopes, the edge of fields, streams, ditches or other water bodies, which can play outstanding roles in soil structure improvement, such as soil texture, porosity, bulk density, and some other physical pro-perties. Its mechanical resistance can delay and intercept runoff effectively, facilitate rainwater infiltration, and reduce the denudation power of runoff on surface land. Moreover, the hedgerows can change sloping topography through constant sediment accumulation at the upper sides of the strips. The international and domestic researches across different ecological zones and geographical regions were summarized and analyzed in this paper. On the basis of such analysis, the hedgerows were confirmed to play a positive role in soil physical and chemical properties, rainfall infiltration, erosion processes, vegetation restoration, biodiversity conservation, landscape optimization and other important ecosystem services. Meanwhile, two problems in the current research of hedgerows were put forward: the planting pattern and structure of hedgerows, species selection, and management practices should be systematized for application, while the mechanisms of hedgerows on vegetation restoration and ecological succession should be further explored in scientific research.