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    10 July 2014, Volume 33 Issue 7
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    Characteristics of sap flow velocities for three tree species in a broad-leaved Korean pine forest of Changbai Mountain, in relation to environmental factors.
    YU Meng-meng1,2, ZHANG Xin-jian3, YUAN Feng-hui1**, HE Xiu1, GUAN De-xin1, WANG An-zhi1, WU Jia-bing1, JIN Chang-jie1
    2014, 33(7):  1707-1714. 
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    Sap flow velocities of Tilia amurensis, Acer mono and Pinus koraiensis in a broad-leaved Korean pine forest of Changbai Mountain were continuously measured from June to September of 2009 using Granier’s thermal dissipation sap flow probe method, with simultaneous measurements of environmental factors. Diurnal and monthly variations of sap flow velocities for the three species and the effects of environmental factors were analyzed. The results showed that diurnal variations of sap flow velocities for three species all displayed singlepeaked curves, and their starting time and peak time were the same. However, their end time showed a difference, and the diurnal end time of sap flow for T. amurensis was the latest. The monthly dynamics of sap flow velocities for the three species also showed a similar pattern, with their maximums appearing in August and minimums in June. Among the three species, the daily average sap flow velocity of T. amurensis was the highest in each month, with the lowest for P. koraiensis. Sap flow velocities of the three species were mainly affected by the photosynthetically active radiation and vapor pressure deficit. Stepwise regression models for predicting sap flow velocities of the three species based on environmental factors were established in each month.
    Pollution characteristics of atmospheric particulates in forest belts and their relationship with meteorological conditions.
    LIU Xu-hui, YU Xin-xiao**, ZHANG Zhen-ming, LIU Meng-meng, RUANSHI Qing-cao
    2014, 33(7):  1715-1721. 
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    In order to understand the blocking effects of forest belts on particulates, the concentrations of particulate matters (PM10 and PM2.5) in different forest belts near the ecological corridor in southern Beijing Olympic Forest Park adjacent to the southern side of North Fifth Ring Road were observed in May 2013, and major meteorological data such as temperature and relative humidity were collected simultaneously. Results showed that the change pattern of PM10 was consistent with that of PM2.5, being highest in the morning (7:00 am) and lowest at about 17:00 pm. The forest belts could reduce the concentration of PM10, but the blocking effect was complicated for the PM2.5. The PM2.5 concentrations decreased in the elm forest belt and mixed forest belt, but the situation was opposite for poplar forest belt. Particle concentrations in the forest changed with the meteorological factors. PM10 and PM2.5 concentrations were negatively correlated with temperature. Increased temperature intensified the atmospheric vertical convection, being conducive to the particle diffusion and thus decreasing the particle concentration. Concentrations of PM10 and PM2.5 had positive relationships with the relative humidity.
     
    Variation of CO2 flux and its response to environmental factors in a maize agroecosystem in Zhangye irrigation area.
    ZHANG Lei1,2,3, SUN Rui1,2,3**, QIAO Chen2, LIU Shao-min1,2, XU Zi-wei1,2, TANG Yao2, HAO Lü-yuan2, ZHANG Rong-hua2
    2014, 33(7):  1722-1728. 
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    CO2 flux was measured continuously in a maize agroecosystem in Zhangye irrigation area during the growing season (June to September) using the eddy covariance technique to study the variation of CO2 flux and its response to key environmental factors. The results showed that there was a distinct diurnal variation of CO2 flux, with CO2 absorption in the daytime and emission at night. The maximum CO2 absorption occurred at filling stage and with a maximum value of -1.426 mg·m-2·s-1. Maize agroecosystem is characterized by carbon absorption during the growing season, and the ability to absorb CO2 is significantly different at different growth stages, which was ordered as filling stage > jointing stage > maturity stage > seedling stage. We also used the MichaelisMenten equation and exponential curve fitting method to analyze the impact of photosynthetically active radiation (PAR) on daytime CO2 flux, and the impact of temperature on the ecosystem respiration at night. The results showed that CO2 absorbing intensity increased with PAR. PAR was the dominant factor to control photosynthesis under low solar radiation, and the carbon assimilation rate increased slowly under high solar radiation. The light quantum efficiency of maize ranged between 0.00098 and 0.0022 mg·μmol-1 during the observing period. The nighttime ecosystem respiration exponentially increased with temperature, and the dominant factor varied with growth stage. Soil temperature was the dominant factor of nighttime ecosystem respiration at the seedling stage, while air temperature was the dominant factor at the other growth stages.
     
    Radon environmental geochemistry in soil gas around the Capital area of China.
    ZHOU Zhi-hua1, ZHAO Feng-fan1**, LI Ying2, ZHOU Xiao-cheng2, HAN Xiao-kun2
    2014, 33(7):  1729-1733. 
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    Radon in the air is mainly released from the rock and soil radon. The geochemical characteristics of radon in soil gas around the Capital area of China were investigated based on the measurements of radon concentrations in Sanhe area, Yanhuai basin and Tangshan area. The mean radon concentrations were 2×104-2.5×104, 1.5×104-2×104, and less than 1.5×104 Bq·m-3in Sanhe area, Tangshan area, and Yanhuai basin, respectively. Overall, the distribution of radon concentration was higher in the east than in the west. Based on the soil radon concentration in the international environmental hazard classification, some parts of the study areas reached to the moderate risk level. Based on China’s standards (code for indoor environmental pollution control of civil building engineering), anticracking and waterproof measures should be taken on the ground floors of buildings in Sanhe area and Tangshan area, while no measures are needed to prevent radon in Yanhuai basin.
    Response of Kobresia tibetica and Kobresia humilis population spatial pattern to soil moisture.
    DANG Jing-jing, ZHAO Cheng-zhang**, DONG Xiao-gang, YANG Quan, ZHA Gao-de
    2014, 33(7):  1734-1740. 
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    Heterogeneity of plant population response to soil moisture is the environmental basis of their pattern’s formation and evolution. According to the pattern of soil water decreasing gradually from the wetland center to the edge, we set up five sampling plots to study the spatial distribution and spatial association of Kobresia tibetica and K. humilis under different soil moistures in north Qilian Mountain by using the point pattern analysis. The results showed that with the decrease of alpine wetland moisture content, the coverage, plant height and aboveground biomass of K. tibetica population were continuously increased, while the main biological features of K. humilis increased firstly then reduced. The distribution pattern of K. tibetica was clumped—regular—clumped and that of K. humilis gradually shifted from aggregation to regularity at small scale. Along with the decrease of soil moisture, the spatial association between K. tibetica and K. humilis population at small scale was positively correlated, then changed into no significant correlation and negative correlation finally. In the alpine wetland, the main biological features and spatial pattern of K. tibetica and K. humilis populations showed regular changes, which reflected the adaptability of the two species in response to habitat heterogeneity under different soil moistures.
    Changes in biodiversity during the succession of plant communities on the rocky slopes of mine in islands.
    LI Lin-xia, WANG Rui-jun, GU Bin**, HE Yu-ling, CHEN Ji-chuan
    2014, 33(7):  1741-1747. 
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    This paper studied the changes in biodiversity during community succession process using various diversity indexes combined with DCA ordination and monadic linear regression analysis, based on the investigation of plant communities on the rocky slopes of mine in Zhoushan Island. The results showed that the succession processes were divided into three stages, i.e., herbaceous stage, shrub stage, and shrubtree stage, respectively. With the development of succession, species richness increased significantly, and the diversity and dominance indices also went up. Meanwhile, the succession process of artificial communities was different from that of natural communities. On the recovered slopes, succession series included the growth stage of  natural immigrants, the competition stage with designed plants, and the stable state where the immigrants coexist with the designed plants. It was obvious that introducing adaptive woody species would shorten the period of succession in the mining area. Our study suggested that reasonable mixtures of species were able to enhance the positive succession during artificial vegetation restoration.
    Effect of long-term fertilization pattern on weed community diversity in rice field.
    JIANG Min1, SHEN Ming-xing2, SHEN Xin-ping1, DAI Qi-gen1**
    2014, 33(7):  1748-1756. 
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    Fertilization can alter the natural succession process of the weed community in cropland by directly improving the yield and competitive advantage of crops and changing the nutrient content and structure of the soil. We investigated the weed community diversity in rice field in a ricewheat rotation system during 2011-2012 after a 31year longterm application of different fertilizers in Taihu Lake, and analyzed the effects of soil nutrients and fertilization on weed distribution. Fertilizer treatments included: CK (no fertilizer), N (N fertilizer), NP (N plus P fertilizer), NK (N plus P fertilizer), PK (P plus K fertilizer) and NPK (N plus P and K fertilizers). The redundancy analysis (RDA) was performed to examine the relationship between fertilizer management and weeds. Among the weeds, Eleocharis yokoscensis, Monochoriav aginalis, Ammannia arenara, and Ceratopteris thalictroides were the dominant species. The longterm application of nitrogen and phosphorus fertilizers could significantly reduce the density of weeds. Phosphorus fertilizer applications significantly reduced the density of sedge and effectively increased the density of M. aginalis, while A. arenara and C. thalictroides grew best in no fertilizer treatment. The application of nitrogen and phosphorus fertilizers could reduce the richness index and increase the evenness index of weed community. In no application of fertilization (CK), the biodiversity of the cropland ecosystem was maintained at a high level, indicating the nofertilizer treatment was adequate to meet the growing needs of most of the weeds. At the heading stage of rice, the eigenvalues of the first and second ordination axes were 0.901 and 0.080, respectively. The coefficients of correlation between the soil total P, Olsen P, total N, available N and the first ordination axis were -0.887, -0.816, -0.810, and -0.794, respectively. Soil organic matter, nitrogen and phosphorus contents were the main environmental factors affecting the distribution of weeds. The results also indicated that the application of different fertilizers affected the community composition of the weeds.
    Soil carbon and nitrogen content in windthrow area on Changbai Mountain after 26 years’ natural recovery.
    MENG Ying-ying1,2, BAO Ye1,2, GUO Yan1,2, WANG Xiao-yu1,2, YU Da-pao1, ZHOU Li1**, DAI Li-min1
    2014, 33(7):  1757-1761. 
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    Changes in the structure and composition of vegetation communities often determine the organic carbon and nitrogen cycles in the soil. In order to explore the soil characteristics of forests on Changbai Mountain naturally recovered 26 years after wind damage, we selected three typical forest types―Korean pine and broadleaved mixed forest, sprucesfir forest and Erman’s birch forest along an altitudinal gradient, and compared the contents of soil organic carbon (SOC) and total nitrogen (TN) in the wind damaged area with those in the undamaged area (control area). Regardless of wind damage, SOC and TN contents were significantly higher in topsoil (0-10 cm) than in subsoil (10-20 cm). Within each forest type, no significant differences were found in SOC and TN contents between the damaged and control area. However, SOC and TN contents of both topsoil and subsoil increased with elevation. SOC and TN contents in topsoil significantly differed among the three forest types, while no differences observed in subsoil. Moreover, in Korean pine and broadleaved mixed forest and sprucefir forest, SOC and TN contents in topsoil were higher in the control area than  in the damaged area. With rising elevation, C/N in both topsoil and subsoil displayed a decrease trend regardless of wind damage. Overall, after 26 years’ natural recovery since the wind damage, the contents of SOC and TN did not differ significantly between the damaged area and the control area, but the ratio of C/N did. Our results suggested that soil quality was largely recovered, but the types of SOC input differed between the damaged area and the control area due to differences in the structure and composition of vegetation communities. Therefore, soil C/N may reflect the effects of vegetation changes on soil better than the contents of SOC and TN.
    Soil seed bank of typical saline wetlands in Tianjin Binhai District and CCA analysis. 
    HE Meng-xuan1, MO Xun-qiang2, LI Hong-yuan1**, MENG Wei-qing2
    2014, 33(7):  1762-1768. 
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    Samples from typical coastal saline wetlands were selected for soil germination experiment. Meanwhile, the soil physicochemical properties were determined. The relationship between soil seed bank (SSB) and soil characteristic factors were studied by using CCA ordination (canonical correspondence analysis). The results showed that the reserves of SSB in four plots were abundant, but most species were coastal indicator halophytes, and its species composition was simple. Compared with artificial wetlands, conserved natural wetlands had the lower seed density, but higher species richness and stable vegetation community structure. The curves of seed germination rate represented an irregular parabolic shape, while the curve of seed quantity represented an Sshaped distribution. The degree of soil compaction had a great influence on soil germination. Soil seed bank showed a significant vertical hierarchy, and the density of SSB decreased with the increase of soil depth. Large numbers of seeds remained in the 10-15 cm soil layer. By CCA analysis, three obvious clusters were presented. The total salt content, organic matter content and pH were main factors affecting the soil seed bank distribution. However, the permeability of soil was also an important factor that couldn’t be ignored.
     
    Responses of soil physicochemical properties and biological activity to continuous application of slow/controlled releasing urea.
    DING Ji-na1,2, LI Dong-po1**, WU Zhi-jie1, CUI Ya-lan1,2, LI Hui-bin1,2, LI Yong-hua3, LI Bo3, JIAO Xiao-yun3
    2014, 33(7):  1769-1778. 
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    The effects of six-year continuous applications of different types of slow/controlled release urea on biological activity and physicochemical properties of aquic brown soil were investigated. The results showed that soil organic matter, total nitrogen, total phosphorus, available phosphorus and available potassium were significantly increased by continuous application of slow/controlled release urea, while total potassium, available nitrogen and pH were significantly decreased. The descent of pH was slowed down by continuous application of slow/controlled release urea compared to the use of normal urea, and the soil pH was higher after application with slowrelease urea than with coated urea. Soil urease activity of slow/controlled release fertilizer treatments was higher than CK. Applications of nitrification inhibitors incorporated and coated urea resulted in the highest nitrate reductase activity and accelerated the nitrification potential activity. Application of nitrification inhibitors incorporated urea significantly increased soil microbial biomass carbon. In conclusion, continuous six-year applications of NBPT+DMPP+U and PCU significantly increased biological activity in contrast to the other treatments. Considering the cost and economic effects of the different fertilizers, the urea supplemented with NBPT and DMPP is suitable for continuous application in aquic brown soil.
     
    Fine root distribution characteristics of lowefficiency Cuprssus funebris stands with different transformation modes.
    FAN Chuan, LI Xian-wei**, ZHANG Jian, LI Ping, LIU Tao
    2014, 33(7):  1779-1785. 
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    Three transformation modes were used to improve the lowefficiency Cupressus funebris stands in Jingyang of Deyang City, Sichuan Province in 2002. The three transformation modes included C. funebris+Alnus cremastogyne+Bambusa pervariabilis×Dendrocalamopsis daii mode (BZQ), C. funebris+Quercus acutissima mode (BL), and C. funebris+B. pervariabilis×D. daii mode (BZ). After eight years of transformation, we investigated the fine root biomass of differently transformed Cuprssus funebris stands in the soil profiles. The results showed that the transformation modes and soil layer affected the fine root biomass significantly (P<0.01). Fine root biomass of BZ and BZQ were significantly higher than that of CB, while the fine root biomass of BL was the lowest. The fine root biomass of C. funebris distributed differently among the different transformation modes, increasing with the increase of soil depth in BZ and BZQ, while decreasing in BL. The proportion of C. funebris dead fine roots in BL was significantly higher than that in the other transformation modes. The distribution of fine root biomass was relatively stable in BZQ, while was poorly stable in BL.
     
    Structure of epiphytic algal community of eelgrass (Zostera marina) in a typical coastal area of Shandong Peninsula.
    NIE Meng, LI Wen-tao**, LI Yong, ZHANG Xiu-mei, QIN Le-zheng
    2014, 33(7):  1786-1794. 
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    In order to study the structural characteristics of the epiphytic algal community of eelgrass (Zostera marina) along Shandong Peninsula, we conducted investigations at Zhanqiao, Qingdao, Shuangdao Bay, Weihai, and Moon Lake, Rongcheng in March (spring), June (summer), September (autumn) and December (winter) 2012. Epiphytic algal communities of eelgrass in different seasons were comparatively analyzed regarding its diversity index and evenness index using cluster analysis and multidimensional scaling analysis (MDS). In total, 17 species were identified, belonging to 3 classes and 14 genera. Among them, there were 4 genera and 5 species of Rhodophyceae, 4 genera and 4 species of Phaeophyceae, and 6 genera and 8 species of Chlorophyceae. The greatest number of species (7) was found at Zhanqiao and Shuangdao in spring, and the lowest (1) at Moon Lake in both autumn and winter. The greatest biomass was found in spring, and the lowest in autumn (Zhanqiao), winter (Shuangdao) and summer (Moon Lake). The Shannon diversity index and Pielou’s evenness index were the lowest at Zhanqiao, while the diversity index was the highest at Shuangdao. The species diversity index and evenness index at the six locations were highest in summer, and lowest in winter. The epiphytic algal community structure varied significantly between at the different locations and at most of the different sampling sites of same locations in different seasons, indicating that seasonal variations and geographical differences played important roles in the variations of community structure.
     
    Effects of nutrient addition on nitrogen, phosphorus and non-structural carbohydrates concentrations in leaves of  dominant plant species in a semiarid steppe.
    WANG Xue1,2, LUO Wen-tao1,2, YU Qiang1, YAN Cai-feng3, XU Zhu-wen1, LI Mai-he1, JIANG Yong1**
    2014, 33(7):  1795-1802. 
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    Nitrogen (N), phosphorus (P), soluble carbohydrates (SC), and starch concentrations in leaves of two dominant grass species, Stipa grandis and Leymus chinensis, were examined based on a sevenyear nutrient addition experiment in a semiarid steppe in Inner Mongolia of China. The experiment included five treatments: control, low P, low N, low N + high P, and high N + low P. Results showed that N, P, SC, starch, and nonstructural carbohydrates (NSC) concentrations in leaves of the two plant species were significantly influenced by nutrient addition (P<0.05). A significant interaction effect (P<0.05) was observed between nutrient addition and plant species. Leaf N concentration was increased (P<0.05) for both plant species under the treatments with N addition; starch content was decreased (P<0.05) for both plants in the low N treatment; leaf SC in L. chinensis was decreased under the low P treatment; while NSC content in leaves of both species significantly decreased (P<0.05) with high N + low P addition. No significant response was observed for all variables in S. grandis leaf to P addition. The comparatively higher leaf C/N， C/P, and SC/starch in S. grandis implied more available carbohydrates and a higher use efficiency of S. grandis in N and P nutrients, while L. chinensis exhibited a competitively stronger feature of absorbing nutrients applied.
    Characteristics of transpiration of rubber trees (Hevea brasiliensis) and its relationship with environmental factors.
    ZHAO Wei1,2, ZHANG Yi-ping1**, SONG Qing-hai1, ZHANG Xiang1,2, JI Hong-li1, Syed Moazzam Nizami1, YU Lei1
    2014, 33(7):  1803-1810. 
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    Transpiration rate of rubber tree (Hevea brasiliensis) was measured continuously from February to November in 2013, using the Granier’s thermal dissipation probe method. The main environmental factors (including air temperature, relative humidity, photosynthetically active radiation (PAR) and soil moisture) were also measured simultaneously. The results showed that the transpiration rate of rubber tree exhibited a unimodal pattern, with the value being higher during the daytime and lower at night. The average transpiration rate and daily transpiration of sunny day were 4 times more than those of rainy day. The transpiration started 0.5-1.0 h earlier and the peak time was 2.0-4.5 h earlier during the rainy season than during the dry season. During the study period, the average daily transpiration was 27.84 kg·d-1. The largest amount of stand transpiration (54.3 mm) occurred in April and minimum (29.6 mm) in November. Environmental factors in terms of their effects on the transpiration rate were ranked as air temperature effects > air relative humidity > PAR > soil moisture in the dry season, and PAR > air relative humidity > air temperature > soil moisture in the rainy season. Despite water deficit during the dry season, the rubber tree can get deep soil water due to its welldeveloped root system, and is not affected by severe water stress.
    Physiological responses of Taxus chinensis var. mairei to SO2 stress.
    SUN Ling-xia, ZHANG Jun-ming, CAI Shi-zhen, LI Xi**
    2014, 33(7):  1811-1817. 
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    In order to investigate the resistance mechanism of Taxus chinensis var. mairei to sulfur dioxide (SO2) pollution, one-year-old potted seedlings were grown in an enclosed fumigation chamber, and the concentration of SO2 was set as 5, 10, 20 and 40 mg·m-3 for various durations. Our results showed that the membrane permeability, the contents of  malondialdehyde (MDA), freeproline and soluble sugar were enhanced with the increase of SO2 concentration and duration, while the contents of chlorophyll a and b decreased. The injury symptoms in leaves were first observed at 20 mg·m-3 SO2 after 5-day exposure. Under the same experimental duration, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were induced greatly at the lower SO2 concentrations and then decreased at the higher SO2 concentrations. The activities of SOD and APX were induced at 5 mg·m-3 SO2, while those of peroxidase (POD) and catalase (CAT) were induced at 10 mg·m-3 SO2. Under the 40 mg·m-3 SO2 stress, the activities of SOD, CAT, POD, and APX were significantly decreased in comparison with those in the control during the whole experimental periods. Our results suggest that Taxus chinensis var. mairei can adapt to 10 mg·m-3 SO2polluted environments with no obvious phenotypic injury through its own stress protection system to improve resistance to SO2, therefore this species can be planted in SO2 polluted areas.
    Effects of waterlogging stress on rice morphology and yield component at the jointing stage.
    NING Jin-hua1,2, LU Kui-dong2**, HUO Zhi-guo3, XIE Na1, HUANG Wan-hua2
    2014, 33(7):  1818-1825. 
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    Conventional rice Xiangzaoxian 45 was used as test material, and waterlogged at different submergence depths (two-thirds submerged and fully submerged) for variable durations (3, 5, 7, and 9 days) at the jointing stage to investigate the influence of waterlogging stress on green leaf’s number, curly leaf’s length, leaf sheath’s length, high tillering and other morphological factors and yield components. Results showed that, in the different submergence depth treatments, the green leaf’s number had a negative correlation with the flooding time, and two-thirds of submergence had a more obvious effect than full submergence. Stems changed obviously in the full submergence treatment, while leaves changed significantly in the two-thirds of submergence. High tillering rate had a positive correlation with the flooding time. Curl leaf’s length had a negative correlation with the flooding time under the two-thirds of submergence, but a positive correlation under full submergence. Leaf sheaths among different treatments, all showing the elongation growth, were not significantly different. The different submergence stresses all increased the unfulfilled grain rate and empty grain rate, and lowered the thousandgrain weight. The treatment of two-thirds of submergence for 9 days had the severest effect, with lowest grain number (34). We discussed the adaptation mechanisms and possible causes for stems, leaves and other morphological characteristics under the different submergence stresses. The results could provide a scientific basis for flooding disaster reduction and disasterresistant breeding of rice for the middle and lower reaches of Yangtze River.
    Effects of different mulching methods on soil fertility and the yield and quality of tomato.
    XIA Dong1,2, LI Jie-ying1,2, WANG Guang-long1,2, JIANG Fang-ling1,2, WU Zhen1,2**
    2014, 33(7):  1826-1832. 
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    An experiment was conducted to investigate the effects of mulching methods on soil fertility and the yield and quality of tomato. Two tomato varieties ‘Zhongyan 988’ and ‘Fenbei 3’ were grown in a plastic greenhouse, and five treatments of mulching methods were used including 1) control where no mulching was used; 2) plastic film mulching; 3) straw mulching; 4) straw mulching on plastic film (straw/film); and 5) plastic film on straw mulching (film/straw). Soil fertility and tomato yield and quality were compared between the four treatments of mulching and the control. The results showed that all mulching methods increased the moisture content in the surface soil. Straw mulching reduced the soil surface temperature, while plastic film mulching and film/straw mulching increased the temperature of soil surface. At the same depth, soil organic matter and available nutrient contents were significantly higher under the film/straw mulching than in the other treatments. The available soil nutrient contents under the different treatments all decreased with soil depth. The yield of tomato fruit was the highest and the quality of tomato fruit was best with the film/straw mulching. In conclusion, ground mulching can improve the soil fertility, and improve the yield and quality of tomato fruit; among the different mulching methods, plastic film mulching on straw was the optimal one.
    Physiological mechanism of Carthamus tinctorius L. seedlings in response to salt stress.
    HAN Yu, SHENG Yan-fei, LUO Xi, SUN Xi-chao, WANG Chang-hai, ZHAO Geng-mao**
    2014, 33(7):  1833-1838. 
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    A hydroponic experiment was conducted to investigate the physiological mechanism of safflower (Carthamus tinctorius) in response to salt stress. Four treatments with various salt concentrations (0, 50, 100 and 150 mmol·L-1 NaCl) were employed and arranged by a completely randomized design with three replications. The results showed that the growth of safflower seedlings was significantly inhibited with the increasing salinity of hydroponic solution, while the effect of salt stress on the roots was less than that on the aerial parts. After a duration of 10 days salt stress, the SOD activity in safflower leaves under salt stress was significantly increased as compared with CK; however, TAOC activity remained unchanged. The contents of soluble protein and sugar among the salt treatments were not significantly different, but significantly increased in comparison with CK. When the safflower was saltstressed for 20 days, the SOD activity in leaves remained unchanged, but the CAT and T-AOC activities increased greatly as compared with CK. Also, the soluble sugar and protein contents greatly increased with increasing the salinity of hydroponic solutions. At 30 days of salt stress, the soluble sugar and protein were markedly accumulated in leaves of safflower. The activities of T-AOC and SOD were significantly decreased as compared with that of CK, while the CAT activity remained unchanged. Therefore, the safflower withstood the salt stress mainly through increasing the levels of osmoregulation substances and active oxygen scavenging capacity at the seedling stage, and the inductive increase of soluble sugar might play a key role.
    Flag leaf vein traits in winter wheat varieties (lines) and their correlation with stomatal traits.
    CHEN Wei-yue1,2, LIU Cun-hai3, LI Yang-yang2,3**-, MIN Dong-hong4
    2014, 33(7):  1839-1846. 
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    Leaf venation decides water transport capacity, while stomatal traits are closely related with water loss. How leaf venation is coordinated with stomatal traits is fundamental to probe the relationship between physiological functions related with water use and their adjustment. Taking winter wheat as an example, we studied leaf vein traits and their relationship with stomatal traits of 15 winter wheat varieties (lines). Density of small longitudinal veins accounted for 65.8% of total leaf vein density. Distance between small longitudinal veins was significantly and positively related with distance between large longitudinal veins and distance between transverse veins. Density of large longitudinal veins and small longitudinal veins were negatively correlated with their distance. Stomatal size on both surfaces was similar, but leaf adaxial surface had a higher stomatal density. Stomatal length, width and density on the adaxial surface were positively related with those on the abaxial surface, a tradeoff relation was found between stomatal length and density for both surfaces. Small longitudinal veins and transverse veins were closely related with stomatal traits, but it was not so for large longitudinal veins. Leaf vein density was positively related with stomatal density on the abaxial surface and total stomatal density, but negatively related with stomatal length on the adaxial surface. These results demonstrated the structural basis of the coordination between leaf water supply and demand in different wheat varieties (lines).
    Expression profiles of Chrysanthemum morifolium phospholipose Dα gene in response to biotic and abiotic stresses.
    ZHU Xiao-chen, SONG Ai-ping, LIU Peng, YANG Shu-jin, CHEN Fa-di, FANG Wei-min, GUAN Zhi-yong, CHEN Su-mei**
    2014, 33(7):  1847-1852. 
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    In present study, the primers specific to CmPLDα from chrysanthemum ‘Jinba’ was designed for qRT-PCR analysis of CmPLDα expression profiles in different tissues and in response to abiotic stresses, and exogenous abscisic acid (ABA) and leaf black spot (Alternaria alternata) inoculation, and the roles of CmPLDα in stress responses were disclosed. Result showed that CmPLDα expressed in root, stem, leaf and flower at higher levels in stem, leaf and flower than in the root. Expression of CmPLDα was little affected by cold while generally inhibited by mechanical wound. Heat stress significantly decreased the expression of CmPLDα. Pi deficiency significantly induced the expression of CmPLDα. CmPLDα expression was induced in the late period of salt treatment but induced quickly by ABA treatment. The expression of CmPLDα increased two days after leaf black spot inoculation. It was suggested that expression of CmPLDα was constitutive, and the gene was involved in a variety of physiological processes including temperature stress, Pi deficiency stress, ABAinduced signals and leaf black spot inoculation.
    Influence of urbanization on bird species diversity in urban parks in Changsha, Hunan Province during the breeding period.
    DENG Jiao, YAN Yu-ying, ZHANG Zhi-qiang, LI Chi, YANG Dao-de**
    2014, 33(7):  1853-1859. 
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    Studying the effect of urbanization on urban bird species diversity and protection measures is very important for the protection of urban birds and the construction of urban parks. To gain an understanding of community, species diversity and habitat of birds in urban parks with differences in area, habitat type, and human disturbance in Changsha, Hunan Province, a line transect method was used to investigate the birds’ distribution in Yuelushan Park, Juzizhou Park, Martyr Memorial Park, Nanjiao Park, and Hunan Forest Botanical Park in early May and early June of 2011 and 2013. A total of 6283 individual birds were recorded, belonging to 74 species, 31 families, and 10 orders. Among them, two species are listed in the second category of the national protected wildlife species in China. Regression analysis of  species number per unit area and park area showed that, with the increase of park area,  the bird species number was decreased. The edge effect of small parks led to more resources and more bird species. Additionally, habitat type, human disturbance, and the food availability were obviously correlated with the bird species and population. Based on the results, we proposed suggestions for the construction of urban parks in Changsha.
    Responses of diurnal activity of common coot (Fulica atra) to recreation disturbance.
    HA Li-ya1, CHENG Kun1, ZONG Cheng1**, LI Jin-bo2
    2014, 33(7):  1860-1866. 
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    Wetland ecotourism is developing rapidly in many areas of China in recent years. Waterbirds are key elements in wetland ecosystems, and recreational activities have the potential to bring about behavioral changes of the birds. Behavioral responses of common coots (Fulica atra) to wetland recreation were investigated in Anbang River Nature Reserve of Heilongjiang Province. The diurnal activities of adult and juvenile common coots were observed separately in a dock area, a boating area and in a control area without recreation activities, using instantaneous scan sampling methods. The results indicated that adult birds in the dock area spent less time on foraging, wandering, and grooming; more time on hiding than those in the control area. Adult coots in the boating area hid and exhibited aggressive behaviors more frequently than those in the control area. Foraging, hiding and escape behaviors of juvenile coots occurred more frequently in the boating area than in the control area. Disturbance from recreation was also revealed by the punctuated foraging rhythm of adults and the shortened foraging peak of juveniles. We concluded that the boating area had fewer recreation impacts on coots than the dock area, and that juvenile birds were better habituated than adult common coots. Because the intensive disturbance has the potential to impact the energy storage of common coots before autumn migration, we propose several management suggestions, such as increasing the plant belt between the roadside and the dock area, planning buffer zones between boats and coot territories, and enhancing recreation and visitor management.
     
    Interspecific correlation of Cephalcia kunyushanica and understory plant species in natural forests in Kunyushan.
    PAN Qi1, LIANG Jun1,2**, ZHU Yan-peng3, NI Yang1, YANG Xiao-yan2，4, YUAN Xiao-wen2，4, MA Lin5, ZHANG Xing-yao1,2
    2014, 33(7):  1867-1873. 
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    Based on the samplecircle method and the 2×2 contingency table of species presence/absence data collected from 50 permanent plots in Kunyushan region, the VR analysis, χ2test, association coefficient, Ochiai association index, Dice association index, point correlation coefficient, Cramer index, and percentage cooccurrence were used in quantitative analysis of the interspecific correlation of Kunyushan webspinning sawfly (Cephalcia kunyushanica, a defoliator) occurrence and adjacent understory plants of natural forests in Kunyushan region. The results indicated that there was a significant positive correlation of overall association existing among Cephalcia kunyushanica and 195 neighboring shrub or herbage plants (P<0.01). The result of χ2test showed a positive association for 83 speciespairs and a negative association for 112 speciespairs. The ratio of negative pairs was higher than positive ones. Furthermore, the insect showed extremely significant positive interspecific correlation relations to 11 species including Carex rigescens, while negative ones to 16 species including Carex siderosticta respectively (P<0.01).

     
    Spatiotemporal variations of ecologically used land in Anqiu City, Shandong Province, China.
    ZHANG Yan-jiao1,2,3, JIA Bao-quan1,2,3**-, MA Ming-juan1,2,3, SONG Yi-hao1,2,3, JIANG Nan1,2,3
    2014, 33(7):  1874-1881. 
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    Land use data of Anqiu City of Shandong Province in 1995, 2000, 2005 and 2010 were used to analyze the dynamic changes of ecologically used land by a combined approach including dynamic degree, transition probability matrix, and spatial autocorrelation analysis. Our objective is to provide a decisionmaking reference for the sustainable development and environmental protection during the construction of a new countryside of Anqiu City. The results indicated that the area ratio of ecologically used land decreased from 14.04% to 13.31% from 1995 to 2010 due to the decreased grassland and water areas and increased forest and unused land areas. In contrast, the construction land continuously increased and the farmland continuously decreased during this period. In the three periods, unstable patches had low area rates of 1.39%, 2.21% and 3.13%, respectively. The area and number ratios of ecologically used land of the unstable patches were relatively low, being 31.09%, 43.21%, 20.52% and 28.24%, 34.06%, 11.28%, respectively. The spatial stability of ecologically used land was relatively low and showed a downward trend. Moran index analysis indicated that the transition of other lands to ecologically used land was spatially clustered, while the transition to nonecologically used land dispersed or was at random. Overall, the ecologically used land moved in the direction of shrinking and the nonecologically used land in the direction of expanding.
     
    Characteristics of building types and spatial distribution in Shinan District, Qingdao.
    ZHANG Pei-feng**, LI Xin
    2014, 33(7):  1882-1887. 
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    To explore the spatial distribution of urban architecture is important for urban planning, building layout and eco-city construction. Based on the threedimensional information of the buildings in Shinan District, Shandong Province in 2012, the buildings were divided into five types as residential building, industrial building, commercial building, educational and medical building and others according to the use properties, and low-rise building, multi-story building, mid-tall story building, high building and super-high building according to the height, respectively. The general statistical and geostatistical methods were used to analyze the characteristics of spatial distribution and composition of building types in Shinan District and its ten sub-districts. The results showed that residential, commercial, multi-story and high buildings were the dominant types, buildings were unevenly distributed, and the composition of building types was significantly different among the ten sub-districts. The spatial differentiation of building types was highly consistent with the regional function and development planning.
    Spatial distribution and sources of water pollution in Haizhou Bay.
    LI Fei, XU Min**, DING Yan-zhe, XU Wen-jian
    2014, 33(7):  1888-1894. 
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    This article aims at identifying the characteristics of water quality in Haizhou Bay and providing a reference for protection and management. Based on the data of environmental investigation carried out in 33 stations in December 2009, the stations were categorized according to the result of cluster analysis which was used to identify the similarities of the stations. The main pollution components and distribution characteristics of the sea water were examined with factor analysis. Spatial clustering analysis showed that the pollution status was greatly different in the northern and southern parts of Haizhou Bay. The stations could be divided into different types due to the influence from estuaries. The pollution types on the north side of Lianyungang Binhai New Area and the north side of Longwang estuary obviously differed from the other stations. Factor analysis showed that the first four components accounted for 47.4%, 16.4%, 13.9% and 9.1% of the total variance respectively, including Linhong estuary pollution impact (nutrient salts, copper, zinc), sediment disturbance of marine engineering activities (lead, copper, zinc), the combined effect of Linhong estuary and Lanshan harbor (dissolved oxygen, mercury) and certain regional pollution impact (chromium). The results indicated that the water quality of Haizhou Bay has an obvious spatial distribution. Therefore, for the station arrangement of marine environmental survey it should take into account the regional difference in order to fully reflect the environmental status of marine water quality.
    Variation pattern of rice irrigation water requirement in Southwest of China.
    FU Na, LIU Xiao-gang**, ZHANG Yan, YANG Qi-liang
    2014, 33(7):  1895-1901. 
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    Crop water requirement is an important basis for irrigation scheduling and water resources planning. Based on the daily meteorological data from 38 stations in Southwest of China during 1951-2012, the rice water requirement was estimated by using FAO Penman-Monteith equation, and the change of reference crop evapotranspiration trend was analyzed for rice. Meanwhile, the variation of rice water requirement in the growth period and the spatial distribution characteristics of reference crop evapotranspiration and irrigation requirement index for rice in Southwest of China were analyzed. The results showed that in recent 62 years, the reference crop evapotranspiration in the southwest area changed insignificantly over time and decreased with-increasing the latitude, which in the growth period accounted for 47.6% of the yearly average value. The water requirements in different growth stages showed a moderate variability, and the tillering and heading stages were the critical period. In Southwest of China, the averages of rice water- requirement and irrigation water requirement were 304.5 mm and 76.9 mm per year, respectively. The rice irrigation requirement index was averaged as 0.24, and increased from the west to the east but was generally less than 0.5. As a result, the degree of dependence of rice on irrigation water requirement was low in the study area.
    Community structure of soil ammonia-oxidizing bacteria along the transitional zone of inland Wuliangsuhai Lake. 
    LI Jing-yu1,2, DU Rui-fang1,2, WU Lin-hui1,2，3, YU Jing-li1,2，3, XU Ji-fei2，3, ZHAO Ji2,3,4**
    2014, 33(7):  1902-1910. 
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    The aim of this study is to investigate soil ammonia-oxidizing bacterial community composition, abundance, phylogenetic relationship and diversity under different plant communities formed in the evolution process of eutrophic inland lake Wuliangsuhai, and to discuss the impacts of soil physicochemical factors on ammoniaoxidizing bacterial community structure. The total DNA was extracted and a clone library was constructed based on amoA gene in order to analyze ammoniaoxidizing bacterial community composition, abundance, phylogenetic relationship and diversity index. Soil substrate conditions were analyzed to assess their effects on ammoniaoxidizing bacterial community composition. The similarity of ammoniaoxidizing bacterial community composition gradually decreased from eutrophic lake sediments to desertification soil. The dominant species significantly changed from the Nitrosomonaslike group to the Nitrosospiralike group. Correlation analysis indicated that the combination of total nitrogen and total water soluble salt had the most significant effect on the ammoniaoxidizing bacterial community structure, and the correlation coefficient was 0.943. The diversity index showed that reed swamp and Nitraria tangutorum desert soil were more suitable for diverse ammonia-oxidizing bacteria to grow. Ammonia-oxidizing bacterial diversity and dominant species changed significantly in the transition zone between wetland sediment and desert soil. Total nitrogen and total water soluble salt are the major environmental factors influencing spatial heterogeneity of ammonia oxidizing bacterial community composition.
     
    Inhibiting effect and mechanism of Trichoderma virens T43 on four major species of forest pathogen.
    YIN Da-chuan1, DENG Xun2, Ilan CHET3, SONG Rui-qing1**
    2014, 33(7):  1911-1919. 
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    Antagonistic culture and growth inhibition were used to assess the inhibiting effects of Trichoderma virens T43 on S-phaeropsis sapinea, Cytospora chrysosperma, Rhizoctonia solani and Fusarium oxysporum. The impacts of ethyl acetate extract of T. virens T43 fermented liquid on the protective enzymes (CAT, POD and SOD) and osmotic adjustment substances (soluble protein, soluble sugar and MDA) of pathogens were used to analyze the inhibition mechanism of T43 on the pathogens. The results showed that T43 and its metabolites significantly inhibited the pathogens. The ethyl acetate extract reduced the activities of protective enzymes in pathogens, with SOD activity decreasing most significantly. The extract also significantly reduced the soluble sugar and protein contents, and increased the MDA content in pathogens, hence destroying cell integrity. This may be one of the inhibiting mechanisms of ethyl acetate extract of fermented liquid of T43 on the growth of pathogens.
    Potential role of the endopytic fungus laccase rLACB3 in the bioremediation of peanut continuous cropping soil.
    ZHU Hong1,2, WANG Hong-wei2, DU Wei2, DAI Chuan-chao2**
    2014, 33(7):  1920-1927. 
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    The accumulation of phenolic acids in soil is one of the main hindrances to continuous peanut cropping. Although laccases secreted by fungi can efficiently transform phenolic acids, the application of laccases in the bioremediation of continuously cropped soil has not been investigated. Therefore, a pot experiment was carried out to study the effect of adding different concentrations of laccase rLACB3 on a continuously cropped peanut soil. After 30 days, the 500 U·kg-1 laccase treatment was superior to those with the 20 and 100 U·kg-1 treatments in soil bioremediation. The populations of bacteria, fungi and Azotobacter in the rhizospheric soil of the 500 U·kg-1 treatment increased by 33.0%, 37.7% and 30.2% respectively, compared with the control. The rhizospheric soil microbial community was analyzed by denaturing gradient gel electrophoresis (DGGE), showing that the Shannon’s indexes of culturable bacteria, diazotrophic bacteria and azotobacter of the 500 U·kg-1 treatment increased by 9.0%, 17.3% and 14.8%, respectively compared with the control. The 500 U·kg-1 laccase treatment also had 41.2%, 43.8% and 35.9% lower levels of the phenolic acids, coumaric acid, 4hydroxybenzoic acid and vanillic acid, respectively compared with the control. The biomass and the number of nodules of the 500 U·kg-1 treatment increased by 17.9% and 17.4%, respectively compared with the control. These results indicated that rLACB3 was a potential candidate for the remediation of the continuously cropped peanut soil.
    Ecological function of bryophyte on karst rocky desertification slopes along mountainous roads.
    JIA Shao-hua1, LI Jun-feng1, WANG Zhi-hui2, ZHANG Zhao-hui1**
    2014, 33(7):  1928-1934. 
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    Bryophyte is one of the main plant groups on karst rocky desertification slopes along mountainous roads. However, the effects of bryophyte on water retention and heavy metals’ enrichment are rarely known. Bryophyte samples and their substrates were selected from the rocky desertification slope along Provincial Guizhou305 Road to study the function of soil and water conservation of bryophyte and their adsorptive ability to heavy metal elements (Pb, Zn and Cd) from atmosphere. The results showed that 33 species belonging to 12 genera and 5 families were reported in the study area. The dominant species were Bryum argenteum, Didymodon fallax, Anombryum gemmigerum, Oxystegus cuspidatus and Weissia edentula. Relative abundance of bryophytes in the rocky desertification slope was negatively related to the rocky desertification area. The average rate of bryophyte’ saturated water absorption was from 849% to 1474%, and the average rate of pedogenesis was from 464% to 1025%. The saturated water absorption quantity was from 4.56×104 to 2.63×105 kg·hm-2, and the pedogenesis quantity was from 4.01×104 to 2.45×105 kg·hm-2. The concentrations of Pb, Zn and Cd in bryophytes were 2.25, 3.98 and 2.49 times as high as in their substrates, respectively. The concentrations of Pb, Zn and Cd in their substrates were 16.86, 54.58 and 0.30 mg·kg-1 respectively, being lower than the background values in Guizhou Province. Correlation analysis showed that the concentrations of Pb, Zn and Cd in bryophytes were not correlated significantly with those in their substrates (P>0.05). The results indicated that bryophytes not only had a strong ability to absorb and reserve water, but also had a high adsorptive ability of heavy metals from automobile exhausts. Therefore, they had an important significance for stabilizing road slopes in karst areas and environmental purification.
     
    Insitu immobilization of mercury in soil using bentonite and diammonium phosphate from a field study.
    XIE Yuan-yan1,2, FENG Xin-bin1**, WANG Jian-xu1
    2014, 33(7):  1935-1939. 
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    The single and combined effects of bentonite and diammonium phosphate additions on the distribution of fractionated Hg in soil and flowering cabbage grown in mercury (Hg) enriched soil were investigated under field conditions at Wanshan mercury mine in Guizhou Province. The results showed that the applications of bentonite, diammonium phosphate, and their mixture increased the dry biomass of the root and shoot of flowering cabbages compared with the control. Especially, the combined treatment resulted in a significant boost of root and shoot dry biomass (4.7 and 4.8 times higher respectively compared to the control). In this combined treatment case, the biomass Hg content was also significantly lower than the control, while this effect was insignificant in the single compound treatments. The flowering cabbages receiving the treatment of 3% bentonite and 0.5% diammonium phosphate had the lowest Hg content in various tissues. Concerning the combined treatments, chemical analysis of Hg fractions present in soil before and after the remediation period indicated a significant decrease in bioavailable Hg (soluble and exchangeable, specifically sorbed fractions) and Fe/Mnoxide bound Hg content, while the contents of the organic bound and residual Hg fractions were relatively stable. The results from this study may provide new insights and useful information for the remediation of Hg contaminated soil.
    Effects of Fe limitation on Chlorella vulgaris-Daphnia carinata food chain.
    CHENG Shu-jun, DU Jing-jing, TIAN Xing-jun**
    2014, 33(7):  1940-1945. 
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    This study aimed to determine the effects of Fe limitation on Chlorella vulgaris-Daphnia carinata food chain. C. vulgaris was cultivated with Fe3+ at five different concentrations between 0-10000 nmol·L-1 for 22 days. C. vulgaris cells were collected to feed D. carinata for 14 days. The growth of C. vulgaris and D. carinata was observed. The results showed that the density and chlorophylla content of C. vulgaris were significantly lower at Fe3+ concentrations between 0-1000 nmol·L-1 than those at Fe3+ concentration of 10000 nmol·L-1. The decline of Fe3+ concentration resulted in that C. vulgaris absorbed less nitrogen but more phosphorus. The body length and the total number of the cumulative eggs of D. carinata decreased gradually with the declining Fe3+ concentration. The final body length and total newborns of D. carinata were 3 mm and 93 at 10000 nmol·L-1 Fe3+ concentration, while 2.6 mm and 60 at 0 nmol·L-1 Fe3+ concentration, respectively. It was indicated that Fe limitation had significant effects on the growth of C. vulgaris and its absorption to nitrogen and phosphorus. The growth and reproduction of D. carinata were inhibited under the condition of Fe limitation. These results suggested that the bottomup effects of Fe limitation on C. vulgaris-D. carinata food chain were significant and this would contribute to exploring the effects of Fe on freshwater phytoplankton and zooplankton.
     
    Effect of habitat fragmentation on biodiversity: A review.
    WU Jing1**, LIU Zhi-min2
    2014, 33(7):  1946-1952. 
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    The relationship between habitat fragmentation and biodiversity has been a hot spot in theoretical ecology. This paper elaborated the concept, connotation and measurement of habitat fragmentation. The main theory, content and progress of habitat fragmentation research were also described. Many issues of habitat fragmentation studies were summarized such as different metrics methods of fragmented landscape pattern, inaccurate research methods and undetected nonlinear effect of habitat fragmentation. More research should be conducted on the effect of habitat fragmentation on biodiversity in semiarid areas. Furthermore, the theory and methods of spatial analysis should be widely applied in this area.
    Effect of community composition and species interactions on the invasion of alien plants.
    YAO Xiang-yang1, LI Wei-tao2,3, ZHENG Yu-long2**
    2014, 33(7):  1953-1959. 
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    Alien plant invasions have become serious environmental and socioeconomic problems and a hot topic of ecological research worldwide. Identifying the mechanisms that contribute to the success of invasive plants is very important for predicting and controlling potentially invasive plants. Biotic resistance hypothesis proposes that many biological factors and processes of native community can repel invaders. However, untill now, it is not clear about community resistance to invasion. In this paper, we reviewed the effects of functional trait diversity of community species, functional trait similarity to invasive species, plantherbivore interactions, plantplnt ineractions and plantsoil microbe interactions on the invasion of alien plants. In future, we should focus on the influences of plantplant interactions under different environments, plantherbivore interaction at different competitive intensities, and plantherbivoremicrobe interactions on the invasion of alien plants. These studies not only can improve the understanding of biological invasion mechanism, but also have a practical application value for protecting biodiversity, which can help us to predict the potential invasion region of the alien plants, and manage the ecosystem effectively.
    Effects of land use change on greenhouse gas fluxes from soils: A review.
    LIU Hui-feng1,2, WU Xing1, LI Ya3, LI Zong-shan1, LIU Guo-hua1**
    2014, 33(7):  1960-1968. 
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    Soil is the main source or sink of greenhouse gases (such as CO2, CH4, N2O). Land use change would influence soil microenvironment and microbial physiological and biochemical processes, and thus significantly affect greenhouse gas fluxes from soils. Under the global change and significant changes in land use, the international community has gradually carried out researches on the effect of land use change on greenhouse gas fluxes from soils. This paper briefly describes the research status of land use change and greenhouse gas fluxes from soils, focuses on the effect of cropland, interconversion of grassland and forest, conversion of wetland to cropland, inner changes in different land use types (forest, grassland, wetland and cropland) on the greenhouse gas emissions, and explains its main impact mechanism from the key processes of greenhouse gases produced from soil. We concluded our review with an analysis of deficiencies in current research, and pointed out some urgent and key directions in future, aiming at providing some value references to carrying out the research in the future.
    Effects of nitrogen enrichment on the greenhouse gas fluxes in natural wetlands and the associated mechanism: A review.
    HU Min-jie, TONG Chuan**
    2014, 33(7):  1969-1976. 
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    Natural wetlands are an important source, sink and convertor of greenhouse gases, and play an important role in stabilizing global climate change. In recent years, the nitrogen (N) enrichment in natural wetland ecosystems through intensive fossil fuel combustion, N fertilizer application and industrial sewage discharge have affected directly or indirectly the production, consumption and flux of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4). Effects of nitrogen input on greenhouse gases have been increasingly received attention. In this paper, the main research progress of effects of nitrogen enrichment on the greenhouse gas fluxes in natural wetlands and the associated mechanisms are reviewed. The effects of nitrogen enrichment on the greenhouse gas fluxes in natural wetlands have positive, negative and ineffective patterns, due to differences in nitrogen fertilizer types and input levels, physical and chemical properties of soil, microbial activity, environmental factors, redox potential and so on. Finally, the problems of current research and some future topics are discussed.
    Review on estuary ecosystem health assessment.
    NIU Ming-xiang, WANG Jun**
    2014, 33(7):  1977-1982. 
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    Estuary ecosystem is usually productive and can provide diverse ecosystem services, however, it is vulnerable to the effects of human activities. Effective assessment of estuary ecosystem health can provide the scientific basis for understanding the status and sustainability of the ecosystem. In this study, we reviewed theories on health assessment of estuary ecosystem, e.g. characteristics, conception and criterion, and summarized the index, technology and evaluation models as well as the rules for index choosing in the present applications. The technology of remote sensing (RS) and geographic information system (GIS) were additionally emphasized. Considering the existing difficulties in the health assessment of estuary ecosystem, we proposed a possible trend of development in this field. New technologies along with the concept, impact mechanism and spatial scale setting were suggested to be further strengthened in the future researches of estuary ecosystem health evaluation.
    Using 13C isotope to investigate O3 effects on C fixation and translocation of rice.
    CHEN Zhan1,2, WANG Xiao-ke2**, SHANG He1
    2014, 33(7):  1983-1988. 
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    The effects of elevated ozone on C fixation and translocation of rice were studied by using 13C isotope techniques. Two ozone treatments were performed: control (CK, with a daily average of 4-10 nL·L-1) and elevated ozone (O3, with an 8 h mean of 110 nL·L-1). Compared to the control treatment, the elevated ozone concentration reduced 13C fixation by 37.8% and 20.0%, increased the sink strength of leaf by 47.3% and 37.5% after one and two months exposure respectively, while reduced the sink strength of stem and root. Ozone exposure induced a significant increase in sink intensity in leaves, and an obvious decrease in root but not a significant effect on stem. The relative specific uptake of leaves was significantly increased by 48.5% and 93.3% after one month and two months of ozone exposure, respectively, and that of root decreased significantly.
    A sustainability evaluation of Xingwen County based on emergy and industrial perspective.
    LI jin-rong, ZHANG Xiao-hong**
    2014, 33(7):  1989-1996. 
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    Sustainability of regional ecosystem influences human production and life directly and indirectly. In order to promote regional sustainable development, it is necessary to explore the development trends of different industries in a region. This paper aimed to investigate the development trends of society, economy and environment of Xingwen County, a mountainous region in southwestern China from 2005 to 2011 by applying emergy analysis. The results showed that the social subsystem developed rapidly, and the pillar industries of Xingwen County transformed from agriculture to industry and tourism. Meanwhile, the rapid development of the industry and the tourism also incurred an increasing pressure on the local environment. The functions of economy, environment and society of the three industries were relatively independent of one another. In a word, the society and economy of this county developed relatively well; however, the rising environmental pressure challenged its sustainable development.