Table of Content

10 July 2012, Volume 31 Issue 07

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Articles

Inter-specific competition between Avena sativa and Vicia villosa in mixed sowing grassland in alpine region of the Qilian Mountain in response to grass density.

ZHANG Jing, ZHAO Cheng-zhang**, SHENG Ya-ping, ZHANG Jun-xia, SHI Li-li

2012, 31(07):  1605-1611. 

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The intensity and transformation of intra- and inter-specific competitions in mixed sowing grassland is affected by the relative density of mixed sowing grass species. From June to September 2010, a replacement series experiment was conducted to establish an Avena sativaVicia villosa mixed sowing grassland in the upper reaches of Shiyang River. Seven treatments with the relative density of A. sativa and V. villosa being 1∶0 (KY), 8∶2 (A), 6∶4 (B), 5∶5 (C), 4∶6 (D), 2∶8 (E), and 0∶1 (KM) were designed to study the changes of the inter-specific competition between annual grass species in mixed sowing grassland under effects of the grasses densities. Affected by the relative density of A. sativa and V. villosa, the intra- and inter-specific competitions of the grass species in different phonological periods were transformed in different degrees. In all mixed sowing treatments, the relative yield of A. sativa (RY_y) increased with its growth, while the relative yield of V. villosa (RY_m) decreased with its growth in treatments A, B, and C but increased in treatments D and E. At the seeding and tillering stages of A. sativa, the two grass species were in a hostile relationship (RYT<1) in all mixed sowing treatments except A, but at later growth stages of A. sativa, the relationship transformed to symbiotic (RYT>1) in all mixed sowing treatments, and the competition of A. sativa was stronger than that of V. villosa (RCC_y>1,RCC_m<1). The competition in all mixed sowing treatments was beneficial to A. sativa (AG<1) in its whole growth period. It was suggested that the intra-and inter-specific competitions in mixed sowing grassland in each phonological period showed an obvious density-dependent phenomenon, realizing the cooperative use of resources between the mixed sowing grass species.

Fine root distribution and underground competition in walnut-soybean intercropping system.

XU Hua-sen, YUN Lei, BI Hua-xing**, GAO Lu-bo, BAO Biao

2012, 31(07):  1612-1616. 

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The method of stratified digging was adopted to study the fine root distribution and underground competition in a walnut-soybean intercropping system in Loess Plateau of western Shanxi, Northwest China, aimed to provide scientific support for the efficient and sustainable management of fruit tree-crop intercropping system in this region. The walnut fine roots in the intercropping system were concentrated in 0-40 cm soil layer, and 55.7% of the roots were mainly distributed within the areas 0.5-1.5 m from walnut tree. Soybean fine roots were mainly distributed in 0-20 cm soil layer, and presented an increasing trend with the increasing distance from walnut tree. The underground interspecies competition between walnut and soybean mainly occurred within the areas 1.0-2.5 m from walnut tree, and was most intense within the areas 1.5-2.0 m from the tree.

Carbon storage of different tree-tea agroforestry systems in Xishuangbanna, Yunnan Province of Southwest China.

XIAO Zi-wei1,2, WANG Li-juan1,2, MAO Jia-mei3, ZHU Xing-zheng3, WANG Xiao-li4, ZHENG Li4, TANG Jian-wei1**

2012, 31(07):  1617-1625. 

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In order to understand the effects of shade tree species on the carbon storage of different treetea agroforestry systems, three plots with a size of 20 m × 25 m were established in each of five different tea gardens, i.e., a monoculture tea garden and four tea gardens with one, two, four, and six shade tree species, respectively in Menghai County, Xishuangbanna. Biomass regression models were constructed by using the DBH of shade trees and the BD (basal diameter) of tea shrubs, soil samples were taken from five layers (0-20, 20-40, 40-60, 60-80, and 80-100 cm) in each plot, and the carbon storage was then estimated, based on the carbon contents in different organs of trees and tea shrubs and in soils. The total carbon storage of monoculture tea garden (223.442 t·hm^-2) was 22.701 and 3.871 t·hm^-2 lower than that of the Cinnamomum pathenoxylumtea and Cinnamomum pathenoxylum+Cunninghamia lanceolatatea gardens, but 10.828 and 5.717 t·hm^-2 higher than that of the tea gardens with four and six shade tree species, respectively. Soil carbon storage accounted for 91.8%-96.0% of the total carbon storage, being the lowest in the tea garden with four shade tree species. The carbon storage of plants only occupied 4.0%-8.2% of the total carbon storage, and increased from the tea gardens with one to four shade tree species but decreased sharply in the tea garden with six shade tree species. Our results suggested that the tree-tea agroforestry systems in Xishuangbanna had a strong capacity of carbon sequestration.  

Biomass and carbon density of main forest ecosystems in Hubei Province.

HU Qing1,2,3, WANG Si-long1,2**, CHEN Long-chi1,2, ZHANG Wei-dong1,2, GONG Chao3

2012, 31(07):  1626-1632. 

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Based on the field investigation data, this paper analyzed the carbon storage and carbon density in the secondary forests under closing hillsides to facilitate afforestation, secondary forests, and plantation forests in Hubei Province. The mean carbon storage of the tree layers in the secondary forests under closing hillsides to facilitate afforestation, secondary forests, and plantation forests was 133.87, 73.42 and 111.62 t·hm^-2, the mean carbon storage of shrub layers was 1.65, 1.40 and 1.52 t·hm^-2, the mean carbon storage of herb layers was 0.13, 0.09 and 0.13 t·hm^-2, and the mean carbon storage of litter layers was 0.47, 1.34 and 0.93t·hm^-2, respectively. With the largest share in trunk, the carbon stored in tree layers was the main contributor to the ecosystem C storage, accounting for 98.35%, 96.29% and 97.74% of the total biomass C in the secondary forests under closing hillsides to facilitate afforestation, secondary forests, and plantation forests, while the carbon storage in understory vegetation (shrub + herb) and litters had the least share, accounting for 1.31%, 1.95%， 1.44% and 0.34%, 1.76% and 0.82%, respectively. The soil carbon storage decreased with depth, and 60% of the total was accumulated in 0-40 cm layer. The carbon density in 0-100 cm soil of the secondary forests under closing hillsides to facilitate afforestation, secondary forests, and plantation forests was averagely 57.04, 66.92 and 54.12 t·hm^-2, respectively, and also decreased with increasing depth. The biomass and the soil carbon storage were larger in the secondary forests under closing hillsides to facilitate afforestation and the secondary forests than in the plantation forests, and the carbon density was in the order of soil (0-100 cm) > tree layer > shrub layer > herb layer > litter layer, indicating that secondary forests under closing hillsides to facilitate afforestation was more helpful to improve forest carbon sink, and the implement of near-nature forest management would be the main approach in promoting the carbon sequestration capacity of forest ecosystems in this region.

Distribution characteristics of soil temperature within and outside a subtropical evergreen broadleaved forest in Ailao Mountains, Yunnan Province of Southwest China.

YU Lei1,3, ZHANG Yi-ping1,2**, SHA Li-qing1,2, TAN Zheng-hong1, SONG Qing-hai1,3, ZHOU Wen-jun1,3, WU Chuan-sheng2

2012, 31(07):  1633-1638. 

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Soil temperature is an important environmental factor of forest climate, which closely relates to plant growth. To deeply understand the variations of soil temperature in forest is beneficial to reveal the functions of forest ecosystem and to assess the environmental benefit of forest. Our analysis on the observation data of soil temperature within a subtropical evergreen broadleaved forest and in an open area nearby in the Ailao Mountains showed that the diurnal variations of soil temperature within and outside the forest presented a singlepeak curve. Compared with that in nearby open area, the diurnal variation of soil temperature in the forest was presented in shallower depths (less than 20 cm). The depth of the diurnal variation of soil temperature in the forest was deeper in spring and autumn (20 cm) than in summer and winter (15 cm). The soil temperature in the forest was lower than that in the open area at each depth, and the diurnal and annual variations of soil temperature in the forest were smaller than those in the open area. Overall, both the diurnal and the annual variation ranges of soil temperature were larger outside the forest than within the forest.  

Wind prevention and sand resistance effects of Artemisia sphaerocephalaandA. ordosica.

MA Quan-lin1,2**, LU Qi1, ZHANG De-kui2, LIU Hu-jun2, JIN Hu-jia2

2012, 31(07):  1639-1645. 

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Artemisia sphaerocephalaandA. ordosica are the two typical desert Artemisia species widely distributing in desert areas, and also, the important dominant species in sand-binding vegetation. In this study, a field survey was conducted on the wind prevention and sand resistance effects of A. sphaerocephalaandA. ordosica at the southern edge of the Tengger Desert, with the related mechanisms analyzed. Both A. sphaerocephalaand A. ordosicawere effective in reducing wind speed, and A. sphaerocephala was more effective than A. ordosica. The reduction degree of the wind speed at different positions at the back of the plants and at different heights above ground surface had distinct difference. At the positions from zero to six times plant height at the back of the plants, the wind speed reduction degree of A. sphaerocephala   at the height of 50 cm above ground surface was obviously bigger than that at the height of 20 cm, but the wind speed reduction degree of A. ordosica at the height of 20 cm above ground surface was obviously bigger than that at the height of 50 cm. At the same wind speeds, the mean wind speed at the height of 20 cm at the back of A. ordosica was half of that ofA. sphaerocephala, but the mean wind speed at the height of 50 cm of A. ordosica was near to that of A. sphaerocephala. A. sphaerocephala was weak whereasA. ordosica was stronger in sand resistance. The sand accumulation volume of A. ordosica reached 45.2±16.1 dm³, and its sand accumulation weight was 72.1±25.7 kg. There was a significant positive correlation between single plant sand accumulation volume and spatial structure of A. ordosica. A. ordosica(with compact architecture) was considered better than A. sphaerocephala (with loose architecture) in wind prevention and sand resistance. A. ordosica was characterized by more primary branches, small branching angle, and large biomass distributing at near-surface layer, which contributed to the strong effect of the plant in wind prevention and sand resistance. This conclusion provided an important basis for the species selection of sand-binding vegetation construction in arid areas.

Flora components of wetland wild seed plants in Northeast China.

LIU Bo1,2, TONG Shou-zheng1,2**, LU Xian-guo1,2

2012, 31(07):  1646-1652. 

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In the wetlands of Northeast China, there are 693 species, 42 varieties, and 12 forms belonging to 257 genera and 72 families. Most of the plants are herbs. The dominant families are Cyperaceae, Compositae, Gramineae, Polygonaceae, Ranunculacea and Scrophulariaceae, and the dominant genera are Carex, Polygonum, Salix, Ranunculus, Scirpus, and Potamogeton.Geographically, the wild plant species include 24 types and 25 subtypes, most of which embody the feature of temperate zone, and some have the feature of tropical zone. Compared with those in other areas, the wild plants in the wetlands of Northeast China have 128 species with the feature of cold zone, accounting for 18.47%. The wild seed plant flora in this region geographically correlates well with that in other regions, especially in the Siberia and the Arctic.

Effects of wintertime low temperature and simulated warming on nitrogen-fixing activity of soil biocrusts.

ZHANG Peng**, LI Xin-rong, HE Ming-zhu, LI Xiao-jun, GAO Yan-hong

2012, 31(07):  1653-1658. 

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Taking the soil algal and moss crusts in natural and revegetated areas at the southeast edge of Tengger Desert as test objects and by using different types of OTC, this paper studied the nitrogen-fixing activities of the crusts under effects of wintertime low temperature and simulated warming. In the OTCs, the increment of wintertime daily air temperature was about 1 ℃, and that of the soil temperature at different depths was about 3.2 ℃. During the experimental period, the average nitrogen-fixing activity of algae crust was 1.2×10⁴ nmol C₂H₄·m^-2·h^-1, which was significantly higher than that of moss crust (0.4×10⁴ nmol C₂H₄·m^-2·h). The nitrogen-fixing activities of algal and moss crusts were significantly positively correlated with the air temperature in whole experimental period, and with the precipitation amount three days before the experiment. Under the low temperature, wet, and freezing conditions in wintertime, the damaged nitrogen-fixing enzyme system because of the intracellular ice formation of crust organisms could be the main reason for the decline of the crust’s nitrogen-fixing activities, while warming could promote the crust’s nitrogen-fixing activities. Our study suggested that under the background of future global warming and precipitation pattern change, the increase of air temperature in wintertime could promote the nitrogen contribution of soil biocrusts to arid area ecosystems.

Responses of invasive weed Mikania micrantha to elevated air temperature.

WANG Rui-long1,2,3, ZHONG Qiu-hua1,2,3, XU Wu-bing1,2,3, SONG Yuan-yuan1,2,3, SU Yi-juan1,2,3, ZENG Ren-sen1,2,3**

2012, 31(07):  1659-1664. 

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In order to evaluate the effects of elevated air temperature under global change on the allelopathy and invasiveness of Mikania micrantha, an important alien invasive plant species in China, this paper studied the seed germination, seedling growth, biomass allocation, volatile components, and allelopathic potential of the plant under effects of three temperature (22, 26, and 30 ℃). After 3 days incubation, the seed germination rate of M. micrantha at 22， 26, and 30 ℃ was 29.2%, 52.4%, and 75.2%, respectively, being the highest at 30 ℃. Elevated temperature also increased the shoot length and biomass allocation to stem significantly. GC-MS and GC analyses showed that elevated temperature altered the chemical composition of the volatiles released from M. micrantha leaves. Bioassay demonstrated that elevated temperature increased the allelopathic effect of M. micrantha volatiles on the growth of Raphanus sativus and Brassica campestris seedlings. The results suggested that elevated temperature promoted the seed germination and seedling growth of M. micrantha, increased its allelopathic potential, and thereby, could accelerate the invasion of the plant.

Phenotypic diversity of natural Litsea cubeba population’s leaf- and fruit traits.

TIAN Sheng-ping, WANG Yang-dong**, CHEN Yi-cun, HAN Xiao-jiao, ZHAN Zhi-yong

2012, 31(07):  1665-1672. 

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In order to reveal the phenotypic variation patterns in the leaf- and fruit traits of naturalLitsea cubeba populations in different distribution areas, an investigation was made on the leaf- and fruit traits of ten natural L. cubeba populations distributed in 7 provinces in the south of Yangtze River. There were significant differences in the leaf- and fruit traits among and within the populations. The mean phenotypic differentiation coefficient (V_st) among the populations was 60.19%, and the variation among the populations was higher than that within the populations, suggesting that the variance among the populations was the main part of the phenotypic variation. The V_st values of fruit shape, leaf shape, fruit weight, and seed weight were 51.27%, 6666%, 54.57% and 72.29%, and the coefficients of variation (CV) for the four phenotypic traits were 6.60%, 16.91%, 19.71% and 13.40%, respectively. Due to the lower V_st and CV of fruit phenotype, the stability of fruit traits was higher than that of other traits. There existed significant correlations among 10 phenotypic traits, but the phenotypic traits had poor correlation with geoclimate factors. The ten L. cubeba populations could be clustered into four groups, but the clustering was not according to the geographic distance because the Mahalanobis distance calculated from all phenotypic traits had no significant correlation with geographic distance, which further revealed that the phenotypic variation of L. cubebaleaf- and fruit traits was spatially discontinuous. These findings provided a foundation for the preservation of L. cubeba germplasm resources and the formulation of related breeding strategies.

Effects of climate change on the occurrence of crop diseases in China.

WANG Li1， HUO Zhi-guo1**, ZHANG Lei1, JIANG Yu-ying2, XIAO Jing-jing3, LU Xiao-feng1,4

2012, 31(07):  1673-1684. 

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Based on the 1961-2010 daily observation data from 527 meteorological stations and the annual data of the crop diseases occurrence area and crop yield in farming areas of China, this paper studied the effects of various meteorological elements (air temperature, precipitation, and sunshine hour) on the occurrence and development of crop diseases in China under climate change. As a whole, the variation of the meteorological elements induced by climate change in recent 50 years benefited the occurrence of crop diseases. The mean annual air temperature increasedat a rate of 0.27 ℃·10a^-1, and a 1 ℃ increase of the mean annual temperature could induce a 60.944 million hm²·time increase of the crop diseases occurrence area. The mean annual average precipitation intensity increased at a rate of 0.24 mm·d^-1·10 a^-1, and the occurrence area of crop diseases would be increased by 65.404 million hm²·time when this precipitation intensity increased by 1 mm·d^-1. The mean annual sunshine hours decreased at the rate of 47.4 h·10 a^-1, and a 100 h decrease of the sunshine hours could induce the crop diseases occurrence area increased by 34.188 million hm²·time. Among the variations of air temperature, precipitation, and sunshine hour under climate change, the increase of air temperature had the most significant effect on the increase of the crop diseases occurrence area, followed by the decrease of sunshine hours, and the increase of mean precipitation intensity, with the standardized regression coefficient being 0.508, -0.374, and 0.112, respectively.

Vegetation-climate classification in Inner Mongolia based on Cvalue and >5 °C accumulated temperature.

SUN Yan-ling1, YAN Xiao-dong2**

2012, 31(07):  1685-1690. 

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C value is a parameter of the water-heat correlative equation proposed by Qiwu Cui (1981), which characterizes the dryness or wetness of a region. Based on the  observation data from 150 weather stations in Inner Mongolia in 1961-1990, this paper calculated the mean annual C value and >5 °C accumulated temperature (AT5) over the 30-year period in this region, and spatially interpolated them into raster grids with 8 km resolution by Kriging. In combining with the map of vegetation regionalization, a scatter plot map of C value and AT5 for ten vegetation zones in Inner Mongolia was produced, which better reflected the relationships between the vegetation zones and climatic indices in Inner Mongolia. The ranges ofC value and AT5 for each vegetation zone were determined. According to the determined C value and AT5, the spatial distribution of the vegetation zones in Inner Mongolia was simulated. Kappa test showed that C value combined with AT5 could better reflect the spatial distribution of vegetation zones in Inner Mongolia. As a comprehensive climatic index, C value could provide important information for simulating the distribution of vegetation zones in Inner Mongolia.

Kuznets curve of carbon emission from energy consumption in Anhui Province of East China based on co-integration analysis.

ZHANG Le-qin1**, Chen Su-ping2, Li Rong-fu2, XU Xin-wang1

2012, 31(07):  1691-1700. 

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The study of the environmental Kuznets curve of carbon emission can not only predict the inflection-point appearance time of carbon emission, but also reveal the dynamic relationship between economic development and carbon emission. According to the IPCC carbon emission calculation method and based on the energy consumption data of Anhui Province, a dynamic measurement was conducted on the carbon emission and its intensity in the Province from 1995 to 2010. By using the simplified EKC model, the EKC models of the total carbon emission, per capita carbon emission, and carbon emission intensity in the Province were established, and, based on the co-integration OLS regression method, the EKC curves of the total carbon emission and carbon emission intensity in the Province were analyzed. The results showed that the total carbon emission in the Province was increased from 44.2058 million tons in 1995 to 119.1332 million tons in 2010, and the per capita carbon emission was increased from 0.74 t in 1995 to 1.74 t in 2010, both of them showing a continuous growth trend. On the contrary, the carbon emission intensity per ten thousand RMB Yuan decreased from 2.44 t in 1995 to 0.97 t in 2010, showing a continuous reduction trend. The EKC curve of the carbon emission in the Province was N-shaped. The scatter diagram with trend lines indicated that the N shaped relationship was very weak, no inflection point existed in EKC curve within a short term, but the inflection point would be appeared in 2027. Also, the EKC curve of the carbon emission intensity in the Province was N shaped, the Nshaped relationship was very weak, and no inflection point  existed in EKC curve within a short term while showing a declining trend. The EKC curve was not supported by the per capita carbon emission in the Province. The above results were conducive to understand the future trend of carbon emission, and provide a basis for developing appropriate emission reduction policies.

Effects of irrigation on winter wheat field temperature at booting stage.

YU Wei-dong1，2**, CHENG Lin1，2

2012, 31(07):  1701-1706. 

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Irrigation is one of the effective measures to resist and alleviate the impact of late frost disaster on winter wheat. Aiming at the strong cold weather process occurred in HuangHuai Area of Central China in April 2010, and through a field experiment with irrigation to prevent frost in Zhengzhou agrometeorological observation station, this paper analyzed the characteristics of air and soil temperature in winter wheat field at booting stage. The results showed that when the environmental temperature dropped, irrigation could increase the minimum air temperature by 0.1-0.6 ℃, compared with no irrigation. The effect of irrigation in increasing air temperature was mainly concentrated in the 5 cm zone above soil surface. In addition, irrigation could shorten the duration of air temperate ≤ 0 ℃ by 1-2 h. The soil temperature under irrigation varied with soil depth, being higher at 0 cm depth but lower at 5-20 cm depth, as compared with no irrigation. Irrigation decreased the coefficient of variance and relative variability of air temperature and 0-5 cm soil temperature, but increased the two indices of 10-20 cm soil temperature. The differences of soil temperature caused by irrigation were distinct at 15  and 20 cm soil depths, but not obvious at other soil depths.

Field screening and comprehensive evaluation of heat-resistance rose varieties in Shanghai.

GAO Jie1,2, JIANG Ling-min1, ZENG Yan1, CHEN Zhi-tao1, ZHANG Dong-mei1**, LU Lin2

2012, 31(07):  1707-1713. 

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Based on the natural climate conditions of Shanghai, and taking flowering period, maximum flower opening rate, relative conductivity, proline content, and light utilization efficiency as the indices of rose heatresistance, the heatresistance of 13 rose varieties in the field was evaluated by the methods of subordinative function analysis, principal component analysis, and hierarchical cluster analysis. Among the 13 varieties, Rosa cv. ‘Abhisarika’, Rosa cv. ‘Black Lady’, and Rosa cv. ‘Red Hat’ had most stronger heatresistance, Rosa cv. ‘Bright Smile’ and Rosa cv. ‘Lawinia’ had stronger heatresistance, Rosa cv. ‘Golden Marie’, Rosa cv. ‘Berrrcrd Buffet’, Rosa cv. ‘Shocking Blue’, Rosa cv. ‘My choice’, and Rosa cv. ‘ANITA PEREIRE’ had midlevel heatresistance, and Rosa cv. ‘Orange Wave’, Rosa cv. ‘Angela’, and Rosa cv. ‘MY KONOS’ had low level heatresistance. Rosa cv. ‘Abhisarika’ and Rosa cv. ‘Bright Smile’ were recommended to be popularized in the gardens and parks in Shanghai and JiangHuai basins.

Effects of vegetation establishment on the methane oxidation and methanotrophs community in landfill biocover.

WANG Feng, ZHANG Xiang-feng**, DONG Shi-kui

2012, 31(07):  1718-1723. 

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In order to search for an effective way to reduce the methane emission from landfill, three columns were installed, two of which were planted with Medicago sativa and Trifolium repens, respectively to simulate the biocover of landfill, and one was taken as the control, with the effects of vegetation establishment on the methane oxidation and methanotrophs community in the landfill biocover investigated. Vegetation establishment could markedly contribute to the decline of substrate moisture, increase of substrate total nitrogen, and the promotion of the diffusion of O₂ and CH₄ in the landfill biocover, being beneficial to the enhancement of methane oxidation in the substrate. At the high-speed phase and declining phase of methane oxidation, the oxidation rate of methane in the columns with vegetation establishment was significantly higher than that in the control, but there was no significant difference between the columns covered with different plants. At the low-speed phase, the methane oxidation had no significant differences between the vegetated columns and the control one, but the methane oxidation rate was significantly higher in the column planted with M. sativa than with T. repens. The microbial community derived from phospholipid fatty acid analysis (PLFA) showed that vegetation establishment promoted the growth of type I methanotrophs in the bottom layer of the columns, and, with the decline of methane oxidation rate, there was a shift from type Ⅰ methanotrophs to type Ⅱ methanotrophs at the bottom layer of the columns.

Responses of bacterial community structure in different soils to chlorimuron-ethyl and acquisition of chlorimuron-ethyl degrading bacterial population.

QIN Sheng-hong1,2, LI Xin-yu1, LI Xu1, XIE Jian-fei1,2, SU Zhen-cheng1, ZHANG Hui-wen1**

2012, 31(07):  1724-1732. 

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By using whole genomic 16S rDNA PCR-DGGE and sequencing analysis, this paper studied the responses of bacterial community structure of eight soil samples collected from different sites in China to chlorimuron-ethyl stress under the conditions of acclimation in laboratory. There was a notable alternation in the bacterial community structure of all eight samples during 10 weeks enrichment culture with the application of chlorimuron-ethyl increased from 100 mg·L^-1 to 500 mg·L^-1. By the end of the enrichment culture, the Shannon indices of the bacterial community changed significantly, with most of bacterial populations disappeared. Moreover, there was a convergence in the bacterial community structure of all soil samples. The sequencing of the distinguished bands from the 10th week DGGE profile showed that after 10 weeks culture, the culturable Methylophilus sp. and Beta proteobacterium and unculturable bacteria became dominant groups. In the sixteen dominant groups, 10 of them had a similarity above 97% to the known organic pollutant degrading bacteria in phylogenetic tree, and 5 of the 10 had a similarity above 98% to Methylophilus sp. A bacterial population was obtained, which could degrade 67% of 100 mg·L^-1 of chlorimuron-ethyl within 5 days. The main composition of the bacterial population was Methylophilussp., Comamonas sp., Sphingobacterium sp., and Hydrogenophilus sp.  

Changes of enzyme activities and available nutrients in rhizosphere soil of transgenic Bt+CpTI cotton during its growth period.

WULAN Tu-ya1,2,3, LI Gang1,2, ZHAO Jian-ning1,2, LIU Hong-mei1,2, HONG Mei3, WANG Hui1,2, YANG Dian-lin1,2**

2012, 31(07):  1733-1737. 

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This paper studied the changes of urease, alkaline phosphatase and catalase activities and nitrate nitrogen, ammonium nitrogen, and available phosphorus contents in the rhizosphere soils of transgenic Bt+CpTI cotton and its parental isoline in different growth periods (30, 60, 90, and 120 d after sowing) under field condition. There was a similar change trend in the rhizosphere soil nitrate nitrogen, ammonium nitrogen, and available phosphorus contents between transgenic Bt+CpTI cotton and its parental isoline, but the change range varied with growth period. The rhizosphere soil alkaline phosphatase activity had less difference between transgenic Bt+CpTI cotton and its parental isoline 30, 60, and 120 d after sowing. Though the urease and catalase activities in the rhizosphere soils had different change trend with the growth of transgeniccotton and its parental isoline, no significant difference was observed in the two enzyme activities at the same growth periods between the two cotton cultivars. Our results indicated that the enzyme activities and available nutrient contents of rhizosphere soil were less affected by transgenic cotton, but mainly affected by the growth period.

Effects of different land use types on soil organic carbon storage and soil respiration.

ZHAO Hong-fei, ZHAO Yang, XU Xiao-niu**

2012, 31(07):  1738-1744. 

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To understand the effects of land use type on soil carbon storage and soil respiration, a comparative study was made to study the characteristics of soil carbon storage and soil respiration under three different land use types, i.e., pure willow plantation (WP), willow-poplar mixed plantation (WPP), and pure poplar plantation (PP) on the lowlands along the Huaihe River in Funan of Anhui Province, East China. The organic carbon storage in 0-30 cm soil layer in WP, WPP, and PP was 6.80, 8.50 and 7.71 g·kg^-1, and the corresponding organic carbon density was 2.88, 3.26, and 2.95 kg·m^-2, respectively. Under the same land use types, both the soil organic carbon storage and density decreased with soil depth. The mean annual soil respiration rate in WP, WPP, and PP was 1.61, 2.33 and 1.61 μmol·m^-2·s^-1, respectively, and the mean daily soil respiration rate was the maximum (6.64 μmol·m^-2·s^-1) in summer and the minimum (0.13 μmol·m^-2·s^-1) in winter. There was an exponential relationship between soil respiration rate and ground surface air temperature, with the R² value being 0.71 for WP, 0.62 for WPP, and 0.54 for PP. The WPP was beneficial to the sequestration of soil organic carbon, as compared to WP, and the lower soil organic carbon storage in WP was related to its extensive management. It was suggested that in the future forest management, reasonable tillage and fertilization should be taken to improve soil fertility and enhance soil carbon sequestration.

Gypsum application in amelioration of soda-alkaline soil.Ⅰ. Determination of economical application amount.

JIN Liang1**, WU Li-geng2, WEI Dan1, HU Ke-lin3, ZHAO Li-bing4， WEI Lu-yu5

2012, 31(07):  1745-1750. 

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Applying gypsum can ameliorate saline-alkali soil, and soil column leaching experiment is one of the methods to verify the amelioration effect. In this study, the ameliorating soil layer was defined as 0-40 cm, and an indoor soil column leaching experiment was conducted. The 0-10 cm soil layer was thoroughly mixed with the calculated amounts of gypsum, and the filtrate was collected to determine the ionic composition which was then converted into salt. Reasoning calculation method was adopted to calculate the amounts of applied gypsum in the processes of dissolution, transformation, and leakage as well as the amounts of the applied gypsum acted with alkaline salts and exchangeable sodium and magnesium. The results showed that after four times of leaching, the physical and chemical conditions of the soil column improved remarkably, infiltration time reduced, soil pH value decreased from 9.25 to 8.20, and soil exchangeable sodium percentage basically reached to 10. There still had some gypsum left. Theoretically, the most economical application amount of gypsum for the amelioration of soda-alkaline soil was 0.05 t·hm^-2.

Effects of different land use types on mosquito community.

SHEN Yuan1**, SUN Jun2, LAN Ce-jie1, XU Lin3, ZHAO Qiang3, CHEN Ji-ping1, DAI Xin1

2012, 31(07):  1751-1755. 

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From 2010 to 2011, an investigation was conducted on the mosquitoes in the construction land (Ⅰ), rural land (Ⅱ), wetland (Ⅲ), forest land (Ⅳ), and arable land (Ⅴ) at 21 sites of Wuxi, Jiangsu Province of East China, aimed to understand the effects of different land use types on mosquito community. A total of 10 mosquito species belonging to 5 genera were found, with an average density being 67.94 ind·lamp^-1·h^-1. The dominant species in the land use types were Culex pipiens pallens in Ⅰ, C. tritaeniorhynchusin Ⅱ, C. pipiens pallens and C. tritaeniorhynchus in both Ⅲ and Ⅳ, and C. pipiens pallens, C. tritaeniorhynchus, Armigeres subalbatus, and Anopheles sinoensis in V. The mosquito density was in the order of Ⅱ> Ⅲ > Ⅴ >ⅣIV >Ⅰ, with a significant difference (P<0.05) among the land use types except between Ⅳ and I. The mosquito biodiversity was in the order of Ⅴ > Ⅳ > Ⅲ > Ⅱ >Ⅰ, being significantly
(P<0.05) higher in Ⅴ and Ⅳ than in Ⅲ, Ⅰ, and Ⅱ. At a similarity of 68%, all the land use types except Ⅳ and Ⅴ had an independent mosquito community. After the lands were transferred to constructed land, the dominant species became C. pipiens pallens  only, and the mosquito density and biodiversity decreased significantly. Under urbanization, C. pipiens pallens and C. pipiens pallensborn disease should be controlled, and the importance of controlling C. tritaeniorhynchus and C. tritaeniorhynchusborn disease would decline.

Role of Rhombomys opimus in the development of “fertile island” in tamarisk mounds in Junggar Basin.

XU Wen-xuan1,2, LIU Wei3, YANG Wei-kang1**, TANG Chao-wen1,2, David BLANK1

2012, 31(07):  1756-1762. 

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Shrub “fertile island” is created and maintained by a combination of physically and biologically mediated processes. Plants are the key factor affecting the formation of “fertile island”, while the activities of burrowing animals can affect the soil physical and chemical properties, which promotes the development of the “fertile island”. In this paper, tamarisk (Tamarix spp.), a dominant shrub species growing in oasisdesert ecotone, and great gerbil (Rhombomys opimus), a widely distributed rodent in Central Asia, were taken as study objects to investigate the “fertile island” effect of R. opimus in tamarisk mounds in Junggar Basin. In the tamarisk mounds without the settlement of R. opimus, “fertile island” effect existed, but the soil nutrients contents had no significant increase. After the settlement of R. opimus, the tamarisk mounds showed obvious “fertile island” effect, with significantly higher soil nutrients contents than the intermound areas. The burrowing activities of R. opimus promoted the enrichment of nutrients in 15-50 cm soil layer, and the content of soil available nitrogen in the tamarisk mounds with R. opimus burrows was over 2 times higher than that in the mounds without R. opimus burrows at the same depths. Our study indicated that the burrowing activities of R. opimus promoted the development of “fertile island” in the tamarisk mounds.

Spatiotemporal distribution and related affecting factors of red tide latent organisms in Zhanjiang Bay, Guangdong Province of South China.

ZHANG Cai-xue, GONG Yu-yan, SUN Xing-li**

2012, 31(07):  1763-1770. 

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An investigation was conducted on the phytoplankton community and environmental factors in the Zhanjiang Bay of Guangdong in February (winter), May (spring), August (summer), and November (autumn) 2009 to analyze the spatiotemporal distribution and related affecting factors of red tide latent organisms in this sea area. A total of 126 red tide latent species were recorded, among which, 85 species of 26 genera belonged to Bacillariophyta, accounting for 67.5% of all species, 36 species of 14 genera were of Pyrrophyta, accounting for 28.6%, 2 species of 1 genus were of Cyanophyta, accounting for 1.6%, 2 species of 2 genera were of Chrysophyta, accounting for 1.6%, and 1 species of 1 genus was of Raphidophyceae, accounting for 0.8%. Eighty nine species occurred in spring, 61 species in summer, 71 species in autumn, and 58 species in winter. The average cell abundances of the red tide latent organisms ranged from 12.36×10⁴ cells·L^-1 to 43.55×10⁴ cells·L^-1, with the maximum in spring, the second in summer, and the minimum in winter. The abundances of the red tide latent species did not reach the threshold value of the outbreak of red tide, according to the cell abundances and cell sizes of the majority of the dominant species in this sea area. There were 31 red tide latent species which occurred in all seasons. The seasonal Jaccard similarity index ranged from 0.43 to 0.50, implying no obvious seasonal succession. A total of 19 dominant species were observed, all of which belonged to Bacillariophyta, and no Pyrrophyta. The species with maximum dominance were Eucampia zoodiacus, Chaetoceros curvisetus, and Skeletonema costatum. No dominant species occurred all year round.S.costatum, C. curvisetus, and Asterionellopsis glacialis were dominated in three seasons. The abundance of the red tide latent organisms were significantly positively correlated to the water body’s chlorophyll a, temperature, salinity, and pH, significantly negatively correlated to the DIN and silicate, but had no significant correlation to the phosphate content.

Community feature of planktonic algae in artificial beach lake, Dishui Lake.

CHEN Li-jing1, JING Yu-xiang1, WU Yan-fang1, LI Juan-ying2, CHEN Chong3, ZHANG Yin-jiang2**

2012, 31(07):  1771-1779. 

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Dishui Lake is the largest artificial beach lake in China. From March 2009 to February 2010, a monthly investigation was conducted on the community feature of planktonic algae in the Lake. Canonical correspondence analysis (CCA) was applied to study the correlations between the algae species diversity and environmental factors by using software CANOCO 4.5, aimed to reveal the responses of the algae community to the ecological environment of the Lake. A total of 186 species and varieties of planktonic algae were detected, belonging to 92 genera of 8 phyla. Chlorophyta had the most species, followed by Cyanophyta and Bacillariophyta. Phorimidium tenus, Merismopedia tenuissima, M. glauca, Microcystis incerta, Oscillatoria tenuis, Cryptomonas erosa, Scenedesmus quadricauda, and Cocconeis placentula were the dominant species. The mean annual abundance and biomass of the planktonic algae were (4552.29±4591.33)×10⁴ cells·L^-1 and 8.15±6.63 mg·L-1, respectively. There was a significant difference (P＜0.01) in the standing crop of the algae between months, but no remarkable difference was detected among sampling stations. The diversity analysis showed that the species diversity was in good condition, and the CCA analysis indicated that the main factors affecting the community structure of the algae were water temperature and total nitrogen in the Lake.

Spatial distribution characteristics of soil moisture and soluble salt contents on the reservoir dam of Sanjiaozhou plain in Dawa County of Liaoning Province, Northeast China.

MAO Yi-xin1,2, WANG Li-hua1**, ZHANG Dan1,2, YIN Li-ming1，LIU Ye1

2012, 31(07):  1780-1784. 

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This paper studied the horizontal and vertical variation and distribution of soil moisture and total soluble salt contents on the reservoir dam of Sanjiaozhou plain in Dawa of Liaoning at different slope aspect and position and different soil depth. As compared with soil moisture content, soil total soluble salt content had a greater variability. Both the soil moisture content and the soil total soluble salt content showed a moderate variability, and their variability was tended to be unanimous. The average soil total soluble salt content was higher on south-facing slope than on north-facing slope, while the average soil moisture content was in adverse. The average total soluble salt content in different soil layers was decreased in the order of middle layer > lower layer > surface layer, while the average soil moisture content was increased with increasing depth. There was no significant difference in the soil total soluble salt content among different slope positions. The average soil moisture content was higher on lower slope than on upper and middle slopes, but had no significant difference between upper and middle slopes. These results provided a reference for the control of saline-alkali soil and the rehabilitation of vegetation on the reservoir dam in Liaohe Delta plain and its surrounding areas.

Effects of di-2-ethylhexyl phthalate (DEHP) on the expression of StAR, CYP17, and CYP19 in Rana chensinensis testis.

LI Miao, ZHANG Yu-hui**

2012, 31(07):  1785-1790. 

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In order to investigate the effects of di-2-ethylhexyl phthalate (DEHP) on the steroid hormone synthesis in amphibian testis, the male adults of Rana chensinensis were exposed to 10^-7, 10^-6, 10^-5 and 10^-4 mol·L^-1 of DEHP for 20, 30 and 40 days, respectively, and the total RNA in the testis was extracted, the cDNA synthesis was performed by reverse transcription, and the relative mRNA expression values of StAR,CYP17 and CYP19 were determined by fluorescence real-time quantitative PCR. As compared with the control, the expression of StAR and CYP19 was up-regulated, and that of CYP17 was down-regulated. The effects of different concentration DEHP on the mRNA expression of StAR, CYP17 and CYP19 were less regular, whereas the cumulative effect of exposure time was more obvious. It was suggested that DEHP could affect the expression of related key enzymes in Rana chensinensis  testis via interfering with the expression of StAR, CYP17 and CYP19 in the testis, and then, interfere with the synthesis of steroid hormones and result in estrogen effect.

Detection of Cu²⁺induced DNA damage of acclimated earthworms by comet assay.

XU Chi, CHEN Jiandong, XU Li, HU Feng, LI Hui-xin**

2012, 31(07):  1791-1797. 

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To study the damage of Cu²⁺ to acclimated earthworms, Eisenia fetida was acclimated under the exposure to a nonlethal concentration of copper (100 mg Cu²⁺·kg^-1) for two weeks, with the un-acclimated E. fetida as the control. The acute toxicity of Cu²⁺ to the acclimated and un-acclimated E. fetida was determined, and the DNA damage of acclimated E. fetida under Cu²⁺ stress (400 mg·kg^-1) was detected by comet assay. On day 14, the 50% lethal concentration (LC₅₀) of Cu²⁺ for acclimated and un-acclimated E. fetida was 321.83-542.45 and 230.83-342.91mg·kg^-1, respectively, and the survival rate of acclimated E. fetida increased significantly. The comet assay showed that the tail length, tail DNA content, and tail moment of the earthworms were in non-normal distribution. On day 11 and day 14, the damaged level of DNA in acclimated E. fetida was much lower than that in unacclimated E. fetida. The results indicated that comet assay was an effective way to detect the gene damage of living E. fetida under copper stress, and the DNA damage of E. fetida could be used as a biomarker to indicate the impacts of heavy metals pollutants.

Aquatic eco-regionalization of Erhai Lake Basin, Yunnan Province of Southwest China.

YANG Shun-yi1,2, TANG Tao1, CAI Qing-hua1**, XIAO Wen3, WANG Xingzhong1,2, LI Feng-qing1,2, TANG Jia3

2012, 31(07):  1798-1806. 

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Delineation of regional boundary is an important procedure in ecological regionalization, but at present, this delineation for aquatic eco-regionalization is mostly dependent on qualitative analysis and expert judgment. In this paper, a two-level eco-region framework was established to delineate the aquatic eco-regions in Erhai Lake Basin. In this framework, sub-basin was taken as the basic unit based on GIS technique, and the indices for the two-level regionalization were quantitatively screened by correlation analysis. Altitude, slope, and normalized difference vegetation index were identified as the indices for level I, and farmland and urban area percentages were the indices for level Ⅱ. The index maps were overlaid and reclassified, and the sub-basins were further merged into several regions. Five levelI eco-regions and nine levelⅡ eco-regions were delineated finally. The examination through the comparison of the distribution of algal communities in different eco-regions showed that the regionalization result was reasonable. It was suggested that applying quantitative analysis and sub-basin boundaries in aquatic eco-regionalization could make the delineation of regional boundary more scientific and the actual management more operational. This study provided a new method for the study of aquatic eco-egionalization, and the basic units for the aquatic ecological management of Erhai Lake Basin.

Characteristics of heavy metals pollution in sediments of four reservoirs from the east coast of Guangdong Province, South China.

ZHANG Hua-jun1, GU Ji-guang1**, HU Ren1, LIN Guo-en1,2, WANG Zhao3

2012, 31(07):  1807-1816. 

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To explore the characteristics of sediment heavy metals pollution and its history of four reservoirs in east coast of Guangdong Province, the main heavy metals Cr, Cd, Cu, Zn, Pb, and Hg in the sediments were detected, and the pollution status of surface sediments was evaluated with geo-accumulation index and Hǎkanson potential ecological risk index, respectively. The possible sources of the heavy metals were also discussed. In the surface sediments of the four reservoirs, the contents of the test heavy metals except Cd all exceeded the Class I values of the China National Standards of Soil Environmental Quality and the highest background values of heavy metals in the global sediments before industrialization, and had great variation between the reservoirs, indicating that the sediments of these reservoirs had been polluted in different degrees. Geo-accumulation index of the four reservoirs showed that the pollution degree of the heavy metals followed the order Pb>Zn>Cd>Cu>Cr>Hg, and Hǎkanson potential ecological risk index indicated that the potential ecological risk of the heavy metals followed the order Cd>Hg>Pb>Cu>Zn>Cr, of which, heavy metals Cd and Hg contributed most to the comprehensive ecological  risk index (RI). The sediment heavy metals contents had a strong correlation with human activities, and the two assessments all showed that the pollution status of Gongping Reservoir and Chisha Reservoir with stronger human activities were worse than that of Hexi Reservoir and Tangxi Reservoir with less human activities.

Urban ecosystem health assessment of Huzhou, Zhejiang Province of East China based on fractal theory.

MA Shuang-shuang1, CHEN Yi1,2, XU You-peng1**

2012, 31(07):  1817-1822. 

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In view of the deteriorating urban ecosystem, a combination of landscape pattern index, water environment parameters, and socio-economic indicators was adopted to build an urban ecosystem health assessment index system. Based on self-similarity theory and fractal theory, the system fractal dimension was calculated, and the link between the fractal dimension and ecosystem health was set up to quantitatively evaluate the urban ecosystem health status and analyze its dynamic trend at different stages of urbanization. By analyzing and calculating the ecosystem fractal dimension of Huzhou City in 1997, 2001, and 2005, the fractal dimensions in the three years were obtained, which were 0.8934, 1.1723, and 1.2619, respectively, foreshowing that the urban cosystem of the City was growing towards an unhealthy condition. This study indicated that the development of Huzhou City’s urbanization had made a negative effect on the urban ecosystem, and thus, more attention should be paid to the ecological and environmental protection during urban planning and onstruction in the future.

Scenarios simulation of land use/cover pattern in Dunhuang City, Gansu Province of Northwest China based on Markov and CLUE-S integrated model.

MA Li-bang1,2**, NIU Shu-wen2,3, YANG Li-na2

2012, 31(07):  1823-1831. 

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A Markov and CLUE-S integrated model was established to simulate the land use/cover pattern in Dunhuang City in 2007, based on the land use/cover change data in 1996 and selecting altitude, slope, distance to river, and distance to road, etc as the driving factors. The simulation results had a high reliability, and matched well with the actual situation. In order to reveal the future changes of the land use pattern in the City, four scenarios were set to predict the land use/cover pattern in the City in 2018. The simulation results showed that whether the scenarios were of natural developmentoriented or only considering ecological protection and economic development, they were only single demand consideration and could not realize sound and rapid development, being of unsustainable development model. However, the comprehensive developmentoriented scenario overcame the shortcomings of the above scenarios, and would be an ideal model of region development, which comprehensively considered the needs of ecological environment restoration and economic development.

Influence of location factor on the changes of three-dimensional architectural landscape in Tiexi District of Shenyang, Northeast China.

ZHANG Pei-feng1,2, HU Yuan-man1**, XIONG Zai-ping1

2012, 31(07):  1832-1838. 

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To study the factors affecting the changes of three-dimensional urban architectural landscape is of guiding significance for the rational distribution and adjustment of future urban landscape. By using buffer belt analysis method, this paper studied the influence of location factors on the changes of three-dimensional architectural landscape in Tiexi District of Shenyang from 1997 to 2008. In the District, the closer to the main roads, the higher the average building height; the closer to the locus of the government, the higher the building coverage ratio and floor area ratio but the lower the building energy consumption; and the closer to the commercial center, the higher the average building height and floor area ratio. Garden and commercial center had minor influence on the urban landscape change.

Landscape pattern changes of construction land in Zhengzhou, Henan Province.

LEI Ya-kai1, YAN Feng1, ZHANG Jun-hong1, HE Dan2, TIAN Guo-hang3**, SUN Hua4

2012, 31(07):  1839-1845. 

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The study of multi-scale spatial pattern is important to comprehensively understand the changes of construction land. In this paper, the TM images in 1989, 2000, and 2009 were used to study the multi-scale pattern and its dynamic changes of construction land in Zhengzhou. From 1989 to 2009, the area of construction land in Zhengzhou increased rapidly, and the patch’s mean area showed a unipolar growing trend. The area of rural construction land increased more slowly than that of urban construction land. At the scale level 0-13 km, the area of construction land in urban core increased gradually, and the patches of the construction land had obvious connection and expansion. At the scale level 13-25 km, the landscape of construction land showed a process of clusterdispersioncluster; while at the scale level 25-58 km, this landscape showed a process of dispersion cluster. Spatially, the area of construction land in the east, north, and southwest of Zhengzhou increased rapidly, the landscape of rural construction land had a smaller variation degree than that of urban construction land, and the landscape of construction land in the middle, western, and northern parts of Zhengzhou had less change.  

Landscape ecological health assessment of tourist islands: A case of Meizhou Island, the Mazu Holy Land of Fujian Province, East China.

LIN Ming-tai1**, YU Jian-hui2, HUANG Jun-chao2, HUANG Jin-huo1, ZHAN Chao-xi3

2012, 31(07):  1846-1854. 

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By defining the concept of landscape ecological health of tourist islands (LEHTI), a LEHTI evaluation system was established with the model of pressure-stateresponse, and an ideal health state value was determined. In addition, by adopting the methods of entropy weight and gray correlation fuzzy, the evaluation results were calculated and classified into five grades, according to their distances to the ideal value. Based on these results, the specific damage of tourist island landscape ecosystem as well as the main stress factors and the evolution trend behind the damage were identified, which could provide scientific basis for the subsequent ecological restoration and optimizing measures. Taking the representative tourist island of Mazu Holy Land as a case, and with the support of RS and GIS techniques, the satellite remote sensing and socioeconomic survey data of 1993, 1999, 2005, and 2009 were integrated and emonstrated. The process and results of this case study showed that the LEHTI evaluation system and its methods were feasible, and could provide solid basis for resource and environment management.

Applications of synchrotron radiation technology in environmental monitoring and ecotoxicology.

BAI Qi-feng, WANG Wen-hua, YUAN Tao**

2012, 31(07):  1855-1861. 

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As the issue of environmental pollution is increasingly serious, relevant studies are moving further and deeper, and more and more high-tech approaches are applied. Synchrotron radiation is a special electromagnetic radiation, which is the tangent radiation induced by circular or snakelike moving electron with a speed close to light. This radiation has high brightness and superior performance, and can be used in a broad energy spectrum. This paper reviewed theapplications of synchrotron radiation in monitoring environmental pollution (water body, atmosphere, and polar region) and in the ecotoxicology of organic pollutants and heavy metals, and discussed the prospects of the applications of this technology in environmental science.

Applications of carbon isotopic method in wetland carbon cycle and related research advances.

CHEN Ling1,2, WANG Zhong-liang1,3**

2012, 31(07):  1862-1869. 

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Wetland carbon pool is one of the important carbon sinks in regional ecosystems, while wetland carbon cycle is an important link in global carbon cycle. However, in the researches of wetland carbon cycle, traditional methods cannot meet our requirements for investigating microscopic mechanisms. Carbon isotopic method, due to its special merit in providing source and process information, has been used as one of the most important tools, helping us probe more detailed mechanisms of wetland carbon cycle. Aiming at the main objects and the basic methods in wetland carbon cycle research, this paper introduced the basic principles of carbon isotopic method and its advantages in carbon cycle research, and summarized the applications of this method in researching wetland biological processes, water body, sediment, and soil, as well as the greenhouse gases emission from wetland. The deficiencies of carbon isotopic research in wetland ecosystem carbon cycle in China and the future directions of this research were also discussed.

Comparisons of azeotropic and vacuum distillation on water extraction efficiency of soil and plant and stable isotope analysis of extracted water.

LIU Wen-ru1,2, SHEN Ye-jie2,3, PENG Xin-hua2, CHEN Xiao-min1**

2012, 31(07):  1870-1875. 

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Hydrogen and oxygen isotope tracing is an important means in studying hydrological cycle in soilplantatmosphere continuum (SPAC), while the extraction of soil and plant water is the critical step to determine the stable isotope composition of the water. This paper compared the efficiency of azeotropic and vacuum distillation in extracting the water from three soil types (red clay soil, red sandy soil, and paddy soil) with three different water contents (35%, 25%, and 15%) and from the stems and leaves of two plants (orange tree and rice), and analyzed the stable hydrogen and oxygen isotopes in the extracted water. As compared with azeotropic distillation, vacuum distillation had a significantly higher water extraction efficiency (P<0.001). Soil type and soil water content had minor effects on the water extraction efficiency, but the extraction efficiency was significantly higher for rice than for orange tree, and for the leaves than for the stems of a given plant (P<0.001). No significant differences were observed in the δ¹⁸O and δD between the water samples from the soils extracted by vacuum distillation and the standard samples, but a significant difference was found in the δD when azeotropic distillation was applied (P<0.001). For the two plants, the δD and δ¹⁸O of the leaves were higher than that of the stems. It was suggested that as compared with azeotropic distillation, vacuum distillation could be more suitable to extract the water from soils and plants, and the extracted water could better reflect the stable isotope composition in the samples.

A composite bioremediation system for water purification.

YUAN Ya-guang1, ZHANG Chi1, XIE Wei-ping2, ZHAO Fu-geng1**, QIN Pei1

2012, 31(07):  1876-1881. 

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By the method of artificial simulation in laboratory, and with water spinach (Ipomoea aquatic), loach (Misgurus anguillicaudatus), and a kind of pseudomonad (Rhodopseudomonas palustris)as the engineering species, a composite bioremediation system of aquatic economic plant  aquatic animal  microorganism was constructed to improve the water quality of sewage. The biomass of I. aquatic and M. anguillicaudatus in the system and the water quality indices were investigated. Within the 23 days experimental period, the nutrient concentrations in the sewage decreased significantly, with the removal rates of NH₄⁺-N, NO₃^--N, TP, and COD_Mn being 96.5%, 82.2%, 53.2%, and 24.5%, respectively. Meanwhile, the biomass of I. aquatic and M. guillicaudatus was averagely increased by 31.2% and 6.1%, respectively. All the results suggested that this composite bioremediation model had good economic and environmental benefits.

Using immobilized microorganism to treat synthetic polluted surface water.

WEI Xiao-na1，2, LI Gang1**, WU Bo1, GUO Shu-hai1, ZHENG Tao3

2012, 31(07):  1882-1886. 

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Taking the polyvinyl alcohol and sodium alginate as embedding agent and the domesticated activated sludge as embedding microbial agent, immobilized microbial granules were prepared with the embedding agent and embedding microbial agent in a ratio of 2∶1. The prepared granules were loaded into a homemade reactor in a filling rate of 20%, and the reactor was used for treating synthetic polluted surface water. The performance of the immobilized microbial granules and their pollutant removal efficiency were investigated. The results showed that the optimum hydraulic retention time (HRT) and influent COD loading rate were 10 h and 1.15-1.85 g·L^-1·d^-1, respectively. At water temperature 25-29 ℃, DO concentration 3-4 mg·L^-1, and HRT 10 h, and when the influent COD and NH₄⁺-N were 70.58-91.76 mg·L^-1 and 13.68-17.82 mg·L^-1, respectively, more than 62.3% of the COD and more than 90.6% of the NH₄⁺-N were removed. It was suggested that the immobilized microbial granules could effectively remove the COD and NH₄⁺-N from polluted surface water.

Controlling effect of three herbicides on an alien invasive plant Bidens frondosa.

WANG Xiao-fei1**, HUANG Zou-yi1, WANG Chuan-you2, WU lei-3, JIN Liang-liang1, MA Min1, ZHANG Yin1

2012, 31(07):  1714-1717. 

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Bidens frondosa is an exotic vicious weed which endangers biodiversity. In this study, a field experiment was conducted to investigate the controlling effect of different concentrations and different application periods of herbicides Starane, MCPA, and glyphosate on B. frondosa. All the three herbicides had significant controlling effect on this weed, with the average lethality of Starane, MCPA, and glyphosate being 92%, 85%, and 82%, respectively, but no significant difference among them. Different concentrations of the herbicides (0.47, 0.40 and 0.33g·L^-1 of Starane; 2.80, 2.33 and 1.87 g·L^-1 of MCPA; and 5.18, 3.89 and 2.59 g·L^-1 of glyphosate) had significant differences in the lethality on B. frondosa, and relatively high concentration could obtain better controlling effect. The application period of the herbicides also had significant effects in controlling B. frondosa. Applying the herbicides at B. frondosa seedling stage (plant height 20 cm) could achieve better controlling effect than at its fast growing stage (plant height 40 cm) and blooming stage (plant height 60 cm). It was suggested that applying 0.47 g·L¹ of Starane at the seedling stage of B. frondosa would obtain the best controlling effect.