Table of Content

18 August 2012, Volume 23 Issue 08

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Articles

Using ecology thinking reconstructing traditional agronomy: Role of production ecology.

WANG Song-liang

2012, 23(08):  2031-2035. 

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Traditional agronomy, as a discipline or specialty, is originated from the reductionism thinking of neoteric experimental sciences and motivated by the great success of industrialized revolution, but loses the ensemble grasp of the relationships between agricultural organisms and their resources and  environment, i.e., agroecosystem mechanism. Moreover, due to the excessively relying on exogenous fossil energy input and the monoculture with a few highly productive crop cultivars, the  agricultural interior sustainability has unceasingly lost, making our mankind facing the double crises of grain security and food safety. Therefore, it is imperative to reconstruct the traditional agronomy and its educational system. In this paper, the author proposed to link traditional agronomy with ecology, establishing agroecology as the core subject and agroecosystem management as the core applied system, and in particular, establishing ‘production ecology’ to fill up the wide gap between the crop cultivation and farming system and the crop genetics and breeding, the two second grade disciplines under agronomy. Ideologically and methodologically, this proposal could provide disciplinary, scientific, and educational bases to authentically implement the strategy of sustainable development of agriculture.

Male Caenorhabditis elegans could enhance the population’s resistance against heat stress.

TANG Zi-wei1, WANG Yun-biao2

2012, 23(08):  2036-2040. 

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The mating system of Caenorhabditis elegans includes selfing hermaphrodites and the males that cross with hermaphrodites. In labcultured C. elegans populations, the proportion of the males is very low, and till now, no detectable fitness of crossed offspring has been found. To explain why the C. elegans conserves a complicated pathway of male development through evolution, we compared the life history of the males and hermaphrodites under heat stress as well as the resistance of the populations with and without males against the heat stress. The results showed that though the life span of the males was more affected by heat stress, as compared with that of the hermaphrodites, the C. elegans populations with the males recovered faster after the stress, and the populations continuously subjected to the heat stress could maintain a higher proportion of the males than the populations cultured at normal temperature. These findings implied that under changeable natural environment, the existence of male C. elegans could be a significant evolutionary strategy for the population survival.

Effects of altitude on soil microbial community in Quercus liaotungensis forest.

ZHANG Di1,2, ZHANG Yu-xin1, QU Lai-ye1, ZHANG Shuang1，2, MA Ke-ming1

2012, 23(08):  2041-2048. 

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Taking the Quercus liaotungensis forest soil in Dongling Mountain of Beijing as the object, and by using chloroform fumigationextraction and phospholipid fatty acid (PLFA) analysis methods, this paper studied the variation characteristics of soil microbial community along an altitudinal gradient in the tree growth season. With increasing altitude, the soil microbial biomass carbon and nitrogen and the quantities of various soil microbial groups in the forest had definite differences but not significant. The ratio of soil bacteria to  fungi increased, but the ratio of G⁺ to G^- bacteria decreased. The soil microbial biomass carbon and nitrogen and the quantities of soil bacteria, fungi, and G⁺ and G^- bacteria had significant positive correlations with the contents of soil moisture, organic carbon, and total nitrogen, and the quantity of soil fungi was positively correlated with soil carbon/nitrogen ratio. The variations of the soil microbial community structure (bacteria/fungi and G⁺/G^-  bacteria) were mainly affected by soil temperature and moisture content, which meant that the soil microbial community structure was sensitive to the environmental conditions. Along with the  global warming, the proportions of soil fungi and G⁺ bacteria in the Q. liaotungensis forests in warm temperate zone would have an increase.

Formation causes of wind damage to Robinia pseudoacacia plantation in Yellow River Delta.

CAO Bang-hua1, ZHANG Yu-juan1, MAO Pei-li2, LI Cheng-bo3

2012, 23(08):  2049-2054. 

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Based on the investigation of the gale-caused damage to the Robinia pseudoacacia plantation in the Yellow River Delta in June-July 2010, this paper measured the morphological indexes and root system characteristics of fallen trees, gap sizes, and soil compactness, aimed to analyze the formation causes of the wind damage to the plantation. Windfalling was the main form of the wind damage to the R. pseudoacacia plantation, and the damage was more serious for the trees with the diameter at breast height of 15-20 cm. For the fallen trees, their tree height and their crown width, height, and taper degree increased significantly with the increase of the diameter at breast height, while the height under branch, the ratio of crown width to height, and the ratio of the height under branch to tree height showed no significant change. With the increase of diameter class, root length had a rapid increase first but a slow increase then, while root mass increased gradually. With increasing forest gap area, the number of fallen trees decreased after an initial increase, being the maximum in the gap areas of 100-150 m². Soil compactness increased with soil depth, but did not show significant changes with the stand diameter class. Increased tree shape factors and suppressed root growth resulting from the increased diameter could be the main  factors causing windfalling, and forest gap played a promotion role.

Analysis of differential proteins in nurse seed grafted unions of Camellia oleifera at its different developmental stages. 

FENG Jin-ling, YANG Zhi-jian, CHEN Hui

2012, 23(08):  2055-2061. 

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By using two-dimensional electrophoresis and mass spectrometry, this paper studied the changes of the proteome in nurse seed grafted unions of Camellia oleifera at its different developmental stages (4, 8, 16, 22, 29, and 35 days after grafting). A total of 40 differential proteins were detected, 9 of which could be related to the healing of nurse seed grafted unions. Grafting stimulated the grafted union’s gene transcription and protein translation, signal transduction, energy metabolism, and compound synthesis and hormone regulation, and activated some enzymes activities, enhanced cell resistance, and promoted the union’s healing.

Effects of sensor’s laying depth for precision irrigation on growth characteristics of maturate grapes.

WANG Yu-ning1,2, FAN Jun1, LI Shi-qing1, ZENG Chen1, WANG Quan-jiu1

2012, 23(08):  2062-2068. 

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In order to approach the appropriate laying depth of soil moisture sensor to control irrigation amount, the sensors were laid at different soil depth to measure the soil moisture content, with the effects of definite irrigation amount on the growth characteristics of maturate grapes studied. The results showed that using the sensor laying at the soil depth 40 cm (SF40) to control irrigation amount, the biological characteristics of the grapes, including photosynthesis, grape yield, and water use efficiency were superior than those when the sensor was laid at the depth 20 cm (SF20) and under conventional furrow irrigation (CK). The grape brix degree in treatment SF40 was slightly lower than that in treatments SF20 and CK, but was still near 20%. In treatment SF40, the irrigated water could infiltrate or redistribute in the soil layers where the main roots of the grapes existed. It was suggested that laying soil moisture sensor at the depth 40 cm could better control the irrigation amount for the maturate grapes in the study area.

Effects of grape seed addition in swine manure-wheat straw composting on the compost microbial community and carbon and nitrogen contents.

HUANG Yi-mei, LIU Xue-ling, JIANG Ji-shao, HUANG Hua, LIU Dong

2012, 23(08):  2069-2976. 

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Taking substrates swine manure and wheat straw (fresh mass ratio 10.5:1) as the control (PMW), a composting experiment was conducted in a selfmade aerated static composting bin to study the effects of adding 8% grape seed (treatment PMW+G) on the succession of microbial community and the transformation of carbon and nitrogen in the substrates during the composting. Seven samples were collected from each treatment, according to the temperature of the compost during the 30 d composting period. The microbial population and physiological groups were determined, and the NH₄⁺-N, NO₃^--N, organic N, and organic C concentrations in the compost were measured. Grape seed addition induced a slight increase of bacterial count and a significant increase of actinomycetes count, but decreased the fungal count significantly. Grape seed addition also decreased the ratio of bacteria to actinomycetes and the counts of ammonifiers and denitrifiers, but increased the counts of nitrifiers, Nfixing bacteria, and cellulosedecomposing microorganisms. The contents of NH₄⁺-N and organic C decreased, while that of NO₃^--N increased obviously. The NO₃^--N content in the compost was positively correlated with the actinomycetes count. During composting, the compost temperature in treatment PMW+G increased more rapidly, and remained steady in thermophilic phase, while the water content changed little, which provided a stable and higher population of actinomycetes and nitrifiers in thermophilic phase, being beneficial to the increase of compost nitrate N.

Applicability of traditional landscape metrics in evaluating urban heat island effect.

CHEN Ai-lian1,2, SUN Ran-hao1 , CHEN Li-ding1

2012, 23(08):  2077-2086. 

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By using 24 landscape metrics, this paper evaluated the urban heat island effect in parts of Beijing downtown area. QuickBird (QB) images were used to extract the landscape type information, and the thermal bands from Landsat Enhanced Thematic Mapper Plus (ETM+) images were used to extract the land surface temperature (LST) in four seasons of the same year. The 24 landscape pattern metrics were calculated at landscape and class levels in a fixed window with 120 m×120 m in size, with the applicability of these traditional landscape metrics in evaluating the urban heat island effect examined. Among the 24 landscape metrics, only the percentage composition of landscape (PLAND), patch density (PD), largest patch index (LPI), coefficient of Euclidean nearestneighbor distance variance (ENN_CV), and landscape division index (DIVISION) at landscape level were significantly correlated with the LST in March, May, and November, and the PLAND, LPI, DIVISION, percentage of like adjacencies, and interspersion and  juxtaposition index at class level showed significant correlations with the LST in March, May, July, and December, especially in July. Some metrics such as PD, edge density, clumpiness index, patch cohesion index, effective mesh size, splitting index, aggregation index, and normalized landscape shape index showed varying correlations with the LST at different class levels. The traditional landscape metrics could not be appropriate in evaluating the effects of river on LST, while some of the metrics could be useful in characterizing urban LST and analyzing the urban heat island effect, but screening and examining should be made on the metrics.

Impacts of road network on forest landscape pattern in Great Xing’an Mountains of Northeast China.

LI Yue-hui1, WU Zhi-feng1, CHEN Hong-wei1, LI Na-na1,2, HU Yuan-man1, CHANG Yu1

2012, 23(08):  2087-2092. 

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By characterizing the composition of road network in the Huzhong Forestry Bureau in Great Xing’an Mountains, Northeast China, we investigated the effects of road networks on landscape pattern by quantifying 1989 landscape pattern for each of the 17 forestry farms on maps with and without roads by principal component analysis (PCA). The results showed that road networks, including the main and secondary timbertransport roads, were distributed evenly among the observed 17 forestry farms with a density of 2.3 m·hm^-2 and spread along the river networks throughout each farm. The emergence of roads significantly altered the landscape pattern at the landscape level in each farm, which was characterized by landscape fragmentation involving a decline in patch area and an increase in patch number and distance among patches. Furthermore, no significant correlation was found between fragmentation and road density. The road network had more impact on fragmentation than on aggregation at the landscape level.

Recreational attraction of urban park wetlands in Beijing.

LI Fen1,2, SUN Ran-hao1, CHEN Li-ding1

2012, 23(08):  2093-2099. 

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Taking the 20 urban park wetlands in Beijing as test objects, a 3-layer evaluation index system including urban park wetland landscape quality, location condition, and accessibility for the recreational attraction of urban bark wetlands was established, and, by using analytic hierarchy process (AHP) and an integrating index evaluation method, the recreational attraction of the urban park wetlands in Beijing was quantitatively assessed, and validated with questionnaire data. In Beijing, the urban park wetlands with high recreational attraction were in the order of the Summer Palace, Olympic Park, Qinglong Lake Park, Beihai Park, Yuanmingyuan Park, Yuyuantan Park, Shidu, Golden Sea Lake scenic area, Taoranting Park, and Yeyahu wetland. The Rice Fragrance Lake wetland and Zhenzhuhu scenic area had the lowest recreational attraction, and the others were fair. The evaluation results were supported by the questionnaire data, which indicated that the index system and evaluation model were useful. According to the recreational services, the 20 park wetlands in Beijing could be clustered into four categories, which could be managed in different ways. Appropriately assessing the recreational services of urban park wetlands could help the decisionmaking on the urban parks optimal planning and designing, improve human living environment, and optimize the spatial distribution of urban landscape.

Possible impacts of the Three Gorges Project and converting farmland into lake on the Microtus fortis population in Dongting Lake region.

ZHANG Mei-wen1, WANG Yong1, LI Bo1, HUANG Guo-xian2, GUO Cong3

2012, 23(08):  2100-2106. 

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The outbreak of Yantze vole (Microtus fortis) population in Dongting Lake region is closely related to the evolvement of lake beaches, because the deposition of lake sediments results in the expansion of lake beaches, which provides the possibility of the increase of the vole’s population. Reclaiming farmland from lake via building cofferdams, eliminating snails by building cofferdams for eradicating schistosomiasis, and overhunting predators in the region cause the voles becoming a pest after the 1970s. In recent years, the Three Gorges Project and the conversion from farmland into lake have had deep impacts on the environment in the Lake region. The dispatching of the down flow rate by the Project induces the expansion of the low and medium level beaches in the Lake region, while converting farmland into lake directly induces the increase of beach area, both of which expand the potential habitats of the vole’s population. Therefore, more attention should be paid on the quantitative variation trend of the vole’s population in the future.  

Phytoplankton’s community structure and its relationships with environmental factors in an aquaculture lake, Datong Lake of China.

LI De-liang1, ZHANG Ting1, XIAO Tiao-yi1, YU Jian-bo1, WANG Hong-quan1, CHEN Kai-jian1, LIU An-min2, LI Zu-jun2

2012, 23(08):  2107-2113. 

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From December 2008 to October 2009, a seasonal investigation was conducted on the phytoplankton’s community structure and its relationships with environmental factors in Datong Lake. With the comparison of the historical data in 1960, the potential effects of intensive aquaculture on the aquatic environment were analyzed, aimed to provide theoretical support for the sustainable fishery of freshwater lakes. A total of 98 phytoplankton species belonging to 7 phyla and 54 genera were collected, among which, Peridinium bipes, Chroomonas acuta, Chlorella vulgaris, Crytomonas ovate, Cyclotella meneghiniana, Crytomonas erosa, Anabaena circinalis, Microcystis aeruginosa, and Anabaena azotica were the dominant species, and had obvious seasonal variations. The mean annual cell density of the phytoplankton was 1.84×10⁶ cells·L^-1, being the highest in summer (16.4×10⁶ cells·L^-1) and ranged from 1.71×10⁶ to 1.98×10⁶ cells·L^-1 in the other three seasons. The values of the abundance index, Shannon index, and Pielou index of the phytoplankton community were 2.01-4.55, 1.26-2.69, and 0.69-1.27, respectively. Canonical correlation analysis (CCA) showed that water depth, water temperature, transparency, and water total phosphorus content, oxidationreduction potential, and electrical conductivity were the main environmental factors affecting the phytoplankton community structure in the Lake.

Effects of the decomposition of poplar and alder mixed leaf litters on soil microbial biomass.

CHEN Qin, FANG Sheng-zuo, TIAN Ye

2012, 23(08):  2121-2128. 

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An incubation test was conducted to study the effects of the decomposition of poplar and trabeculate alder leaf litters with different mixed ratios and under different application ways on soil microbial biomass carbon (MBC) and nitrogen (MBN). The mixed ratio of the litters had significant effects on soil MBC and MBN. On the 30th day of incubation, soil MBC and MBN were significantly higher in the treatments with ≥50% of alder litter than in the treatment with poplar litter only and the control. On the 75th day of incubation, the soil MBC in the treatments with ≥40% of alder litter and the soil MBN in the treatments with ≥30% of alder litter were significantly greater than those in the treatment with poplar litter only and the control. After 135 days incubation, soil MBC and MBN were significant higher in the treatments with ≥20% and ≥40% of alder litter than in the treatment with poplar litter only and the control, respectively. There was no significant difference in the soil MBC/MBN between the treatments with different mixed ratios of poplar and alder leaf litters and the control. Overall, soil MBC/MBN increased during the early period of incubation and decreased in the later period, suggesting that soil microflora changed during the decomposition of the litters. In the whole incubation period, the application ways of the litters had lesser effects on the soil MBC, MBN, and MBC/MBN, indicating that the addition ways of the litters did not affect soil microflora.  

Effects of simulated nitrogen deposition on soil enzyme activities in a Betula luminifera plantation in Rainy Area of West China.

TU Li-hua1, HU Hong-ling1,2, HU Ting-xing1, ZHANG Jian2, XIAO Yin-long1, LUO Shou-hua1, LI Ren-hong3, DAI Hong-zhong1

2012, 23(08):  2129-2134. 

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From January 2008 to January 2009, a field experiment was conducted to investigate the effects of simulated nitrogen (N) deposition (0, 5, 15, and 30 g N·m^-2·a^-1) on the soil enzyme activities in a Betula luminifera plantation in Rainy Area of West China. As compared with the control (0 g N·m^-2·a^-1), simulated N deposition stimulated the activities of soil hydrolases (β-fructofuranosidase, cellulase, acid phosphatase, and urease) significantly, but depressed the activities of soil oxidases (polyphenol oxidase and peroxidase). These results suggested that the increased exogenous inorganic N could stimulate soil microbial activity and increase the demands of both B. luminifera and soil microbes for C and P, whereas the depress of soil polyphenol oxidase and peroxidase activities under N addition could inhibit the degradation of litter and promote its accumulation in soil, leading to the increase of soil C storage in the B. luminifera plantation ecosystem.

Characteristics of soil microbial community structure in Cunninghamia lanceolata plantation.

XIA Zhi-chao1,3, KONG Chui-hua1,2, WANG Peng1, CHEN Long-chi1,2, WANG Si-long1,2

2012, 23(08):  2135-2140. 

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By using dilution plate, fumigation extraction, and phospholipid fatty acid (PLFA) methods, this paper studied the quantities of soil microbial populations and the characteristics of soil microbial community structure in a Chinese fir (Cunninghamia lanceolata) plantation converted from an evergreen broadleaved forest. The results showed that, during the vegetation change from evergreen broadleaved forest to Chinese fir plantation, the microbial biomass carbon and the quantities of culturable bacteria and actinomyces were decreased. The total PLFAs, bacterial PLFAs, and fungi PLFAs in the woodland soil from Chinese fir plantation were decreased by 49.4%, 52.4%, 46.6%, simultaneously. And G⁺ and G^- bacterial PLFAs in Chinese fir plantation were lower than in evergreen broadleaved forest. As compared with those in rhizosphere soil from Chinese fir plantation, the microbial biomass carbon and the quantities of culturable bacteria and actinomyces in bulk soil were decreased. The total PLFAs, bacterial PLFAs, and G⁺ and G^- bacterial PLFAs in the rhizosphere soil were increased, while the ratio of fungal to bacterial PLFAs was lowered. The principal component analysis of the soil microbial community structure indicated that the first principal component (PC1) and the second principal component (PC2) together accounted for 78.2% of total variation of soil microbial community structure. This study showed there were some differences in the soil microbial community structure between evergreen broadleaved forest and Chinese fir plantation.

Diurnal variation of Quercus variabilis trunk diameter in response to environmental factors at south aspect of Taihang Mountains.

SUN Shou-jia1, MENG Ping1, ZHANG Jin-song1, JIA Chang-rong2, REN Ying-feng2

2012, 23(08):  2141-2148. 

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By using Circumference Dendrometer 2 (DC2), this paper studied the diurnal variation of trunk diameter in Quercus variabilis plantation at the south aspect of Taihang Mountains. During seasonal drought, the diurnal variation of Q. variabilis trunk diameter was quite evident. The time of the diameter shrinkage followed the startup time of sap flow, but the appearance of the minimum trunk diameter lagged behind the maximum sap flow flux about 3-4 h. The maximum daily shrinkage (MDS) value of the trunk diameter presented a trend low-high-low, being significantly correlated with the diurnal differences of cumulative sap flow flux and leaf water potential and having a significant quadratic relationship with soil moisture content. The MDS value was affected by the variations of meteorological factors, being significantly correlated with the diurnal variations of air temperature, vapor pressure deficit, and relative humidity, but less correlated with the diurnal variation of solar radiation. After successive precipitation, soil moisture content was no longer the limiting factor of the diurnal variation of Q. variabilis trunk diameter. The MDS value had less correlations with the diurnal differences of cumulative sap flow flux, leaf water potential, soil moisture content, and other meteorological factors. Stepwise regression analysis indicated that the soil moisture content and air temperature in seasonal drought and rain seasons were the key factors affecting the diurnal variation of Q. variabilis trunk diameter.

Temporal variation of soil greenhouse gases fluxes in a coldtemperate Larix gmelinii forest in Inner Mongolia, China.

MA Xiu-zhi1, ZHANG Qiu-liang1, LI Chang-sheng2, CHEN Gao-wa1, WANG Fei1

2012, 23(08):  2149-2156. 

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By using static chambergas chromatograph technique, an in situ measurement was conducted on the soil CH₄,CO₂, and N₂O fluxes in a coldtemperate Larix gmelinii forest in Inner Mongolia from June to September 2007, aimed to understand the diurnal and seasonal variations of soil greenhouse gasses fluxes and their relations with the associated environmental factors in L. gmelinii forests in coldtemperate zone. In growth season, the soil in the L. gmelinii forest was the sink of atmospheric CH₄, with the flux ranged from 22.3 to 107.8 μg CH₄C·m^-2·h^-1. The mean monthly uptake of CH₄ in June, July, August, and September was 34.0±7.1, 71.4±9.4, 86.3±7.9, and 40.7±6.2 μg·m^-2·h^-1, respectively. The mean diurnal flux of soil CH₄ from June to September showed the same variation trend, i.e., peaked at 10:00 am. The diurnal variation of soil CO₂ flux showed an obvious doublepeak, and the mean monthly CO₂ flux was in the order of July>August>June> September. Soil N₂O flux varied dramatically from -9.1 to 31.7 μg·m^-2·h^-1. Soil temperature and humidity were the main factors affecting the CH₄ and CO₂ fluxes, and soil temperature mainly affected the N₂O flux. In the L. gmelinii forest, the CH₄, CO₂, and N₂O fluxes measured at 10:00 am could represent the diurnal CH₄, CO₂, and N₂O fluxes on the same day.

Nitrogen fixation potential of biological soil crusts in southeast edge of Tengger Desert, Northwest China.

ZHANG Peng, LI Xin-rong, ZHANG Zhi-shan, PAN Yan-xia, LIU Yan-mei, SU Jie-qiong

2012, 23(08):  2157-2164. 

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Taking  three typical types of biological soil crusts (BSCs), i.e., cyanobacterialalgal crust, lichen crust, and moss crust, in the southeast fringe of Tengger Desert as test objects, this paper studied their nitrogen fixation potential, seasonal fluctuation, and responses to the environmental factors from June 2010 to May 2011. During the whole study period, the nitrogenase activity (NA) of the cyanobacterialalgal, lichen, and moss crusts had significant difference, being 14-133, 20-101, and 4-28 μmol·m^-2·h^-1, respectively, which indicated the critical role of the species composition of BSCs in nitrogen fixation. The NA of the three crust types had similar response characteristics to environmental factors. The NA had less correlation with the precipitation during the study period, but was positively correlated to the <3 mm precipitation in the former 3 days of the experiment, indicating that the three types of BSCs could reach the maximum rate of nitrogen fixation under 3 mm precipitation. The NA of the three crust types had a significant quadratic functional relationship with air temperature, i.e., decreased after an initial increase. The NA of cyanobacterialalgal and lichen crusts declined rapidly when the temperature exceeded 30 ℃, while the NA of moss crust began to decline when the temperature exceeded 25 ℃, suggesting that different types of BSCs had different optimal temperature range of nitrogen fixation. The seasonal change of the NA of the three crust types was in the order of autumn > spring > summer > winter. The high air temperature in summer and the low air temperature (<0 ℃) in winter inhibited the NA of the crusts, while the suitable water and heat conditions in late spring and early autumn promoted the NA, which implied that the seasonal fluctuation of the NA was mainly controlled by the joint effect of the water and heat conditions. Under humid condition, the BSCs in the temperate desert zone had nitrogen fixation capacity throughout the year, and the controlling effects of environmental factors on the nitrogen fixation were hierarchical. Water condition was the key factor affecting the nitrogen fixation rate and duration of the crusts, while under the conditions of sufficient water supply and carbon storage, heat condition dominated the crusts nitrogen fixation rate.  

Characteristics of soil mineralizable carbon pool in natural restoration process of Karst forest vegetation.

HUANG Zong-sheng1,2, YU Li-fei1, FU Yu-hong1

2012, 23(08):  2165-2170. 

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By the method of taking space instead of time, an incubation test was conducted to study the characteristics of soil mineralizable carbon pool during the natural restoration of Karst forest vegetation in Maolan Nature Reserve, Guizhou Province of Southwest China. It was observed that the contents of soil total organic carbon (TOC) and mineralizable carbon (MC) as well as the carbon mineralization rate decreased with increasing soil depth but increased with the process of vegetation restoration. The amount of cumulative released carbon and the carbon release rate increased with the process of restoration, but the release rate decreased with increasing incubation time. The soil MC/TOC increased with the restoration process but had less change with increasing soil depth, while the qCO₂ decreased with increasing soil depth and through the process of restoration. The soil MC had a negative correlation with the existing litter amount (r=-0.796) but positive correlation with the mass loss rate of the litter decomposition (r=0.924). Soil habitat changed from strong interference at early stages to relative stability at late stages, and soil carbon sequestration changed from small capacity and strong potential at early stages to large capacity and weak potential at late stages.

Responses of Scutellaria baicalensis Georgi yield and root baicalin content to the fertilization rates of nitrogen, phosphorus, and potassium.

CAO Xian-yan1, XU Fu-li2, WANG Wei-ling1, WANG Jing1, HUANG Shu-hua1, ZHANG Xiao-hu3 

2012, 23(08):  2171-2177. 

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A field experiment with three-factor (N, P, and K) and quadratic saturation D-optimal design was conducted to evaluate the effects of the fertilization rates of N, P, and K on the yield and root baicalin content of Scutellaria baicalensis Georgi at harvesting time. A ternary quadratic polynomial mathematical model was built, in which, the N, P, and K fertilization rates were independent variables, and the yield and root baicalin content were the target functions. Through the analysis of the model, the optimum fertilization pattern was obtained. The results showed that the fertilization rates of N and P had significant effects on the yield of S. baicalensis. Under low  fertilization level, the yield increased with increasing N and P fertilization rates; after exceeding definite fertilization range, no obvious effects were observed. N, P, and K fertilization all had significant effects on the root baicalin content. With increasing fertilization rates of N and K, the root baicalin content rates decreased after an initial increase. Under low  fertilization level, the root baicalin content increased with increasing P fertilization rate first, and kept stable then. There existed interactive effects between the fertilization rates of N and P, N and K, and P and K on the yield and root baicalin content of S. baicalensis. Under our experimental conditions, the optimum fertilization model for obtaining over 4000 kg·hm^-2 of S. baicalensis yield and >14% of root baicalin content was 90.5-1047 kg·hm^-2 of N, 163.9-199.9 kg·hm^-2 of P₂O₅, and 84.1-140.8 kg·hm^-2 of K₂O, with an N：P₂O₅：K₂O ratio of approximately 1：1.86：1.15.

Effects of elevated atmospheric ozone concentration on flag leaf photosynthetic pigment contents of wheat.

ZHU Xin-kai1, GAO Chun-yan1, ZHANG Ru-biao1, LIU Ting-ting1, LI Chun-yan1, GUO Wen-shan1, ZHU Jian-guo2, Kazuhiko KOBAYASHI3

2012, 23(08):  2178-2184. 

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By using a freeair controlled enrichment (FACE) system, this paper studied the effects of elevated atmospheric ozone (O₃) concentration (150% of ambient O₃) on the flag leaf photosynthetic pigment contents of wheat varieties Yannong 19, Yangmai 16, Jiaxin 002, Yangmai 15, and Yangfumai 2. For the test varieties, no significant differences were observed in the flag leaf chlorophyll a, chlorophyll b, chlorophyll (a+b), and carotenoid contents between treatments elevated O₃ concentration and ambient O₃ at booting and anthesis stages, but the photosynthetic pigment contents in treatment elevated O₃ concentration all decreased after anthesis, with a significant decrease of chlorophyll a, chlorophyll b, and chlorophyll (a+b) contents, which indicated that elevated O₃ had minor effects on the synthesis of photosynthetic pigments but accelerated their decline process. Different wheat varieties had genetic difference in the responses of flag leaf photosynthetic pigment contents to elevated O₃, among which, Yangmai 15 and Jiaxin 002 had better tolerance to ozone stress. The flag leaf chlorophyll a, chlorophyll b, and chlorophyll (a+b) contents at grain-filling stage (about 21 days after anthesis) had a significant positive correlation with the 1000grain mass.  

Effects of acetochlor on the photosynthetic and fluorescence characteristics and chloroplast structure of grape leaves.

TAN Wei, LIANG Ting, ZHAI Heng

2012, 23(08):  2185-2190. 

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Taking oneyear old sandcultured Kyoho (Vitis vinifera×Vitis labrusca) grapevines as test materials, this paper studied the effects of spraying acetochlor on the grape leaves photosynthetic and fluorescence characteristics and chloroplast ultra-structure. On the 13th day after spraying acetochlor, the net photosynthesis rate and stomatal conductance of upper-node leaves decreased significantly, so as the maximal photochemistry of PSII and the quantum yield of PSII electron transport. The relative variable fluorescence in the J step and K step of the chlorophyll fluorescence transients had an obvious increase, while the performance index (PI_ABS) had a marked decrease. The damages to the PSII reaction center and oxygen-evolving complex of upper-node leaves were more severe, as compared to middle-node leaves, but the damage degree was alleviated along with treatment time. On the 60th day after spraying acetochlor, the differences in the photosynthetic and chlorophyll fluorescence parameters between upper- and middlenode leaves diminished. The responses of bottomnode leaves appeared later than those of the upper- and middle-node leaves. The damage of PSII reaction center and oxygenevolving complex, the rise of relative variable fluorescence in the J step and K step, and the decline of PI_ABS of bottomnode leaves were much greater than those of the upper- and middle-node leaves. On the 60th day after spraying acetochlor, the leaf sugar and starch contents increased, but the pigments in the upper- and middle-node leavesdecreased significantly, the chloroplast membrane was impaired, the size of chloroplasts decreased, and the lamellae became fuzzy or the gap between lamellae increased. As a whole, acetochlor could be transmitted to the aboveground part of grapevine, and result in the damage of leaf photosynthetic apparatus and the decrease of PSII activity and photosynthetic rate.

Effects of strip planting and fallow rotation on the soil and water loss and water use efficiency of slope farmland.

HOU Xian-qing, LI Rong, HAN Qing-fang, JIA Zhi-kuan, WANG Wei, YAN Bo, YANG Bao-ping

2012, 23(08):  2191-2198. 

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In order to enhance the soil water-retaining capacity of slope farmland and reduce its soil and water loss, a field study was conducted in 2007-2010 to examine the effects of strip planting and fallow rotation on the soil water regime, soil and water loss characteristics, and water use efficiency of a 10°-15° slope farmland in the arid area of southern Ningxia, Northwest China. Compared with the traditional nostrip planting, strip planting and fallow rotation increased the soil water content in 0-200 cm layer significantly, with an increment of 4.9%-7.0%. Strip planting and fallow rotation pattern could also effectively conserve the soil water in rain season, and obviously improve the soil water regime at crops early growth stages. As compared to nostrip planting, strip planting and fallow rotation increased the soil water content in 0-200 cm layer by 5.4%-8.5%, decreased the surface runoff by 0.7-3.2 m³·hm^-2, sediment runoff by 0.2-1.9 t·hm^-2, and soil total N loss by 42.1%-73.3%, while improved the crop water use efficiency by 6.1%-24.9% and the precipitation use efficiency by 6.3%-15.3%.

Effects of soil type and crop genotype on cadmium accumulation in peanut (Arachis hypogaea) kernels.

WANG Shan-shan1,2, ZHANG Hong1, WANG Yan-hong1, WANG Shi-cheng1, CUI Jie-hua1, LI Bo1,2, YANG Jing-jing1

2012, 23(08):  2199-2204. 

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Taking burozem and fluvo-aquic soil in the main peanut (Arachis hypogaea) production areas of China as test soil types and selecting three widely cultivated peanut genotypes Baisha 1016, Huayu 22, and Zhanyou 27 as test crops, a pot experiment with no Cd addition (control) and added with 1.5 mg·kg^-1 of Cd was conducted to elucidate the effects of soil type and crop genotype on the cadmimum (Cd) accumulation in peanut kernels. In the control, the Cd concentrations in the kernels of the three peanut genotypes growing on the two soil types were lower than the national food safety standard. In treatment Cd addition, the opposite was observed. For the same soil types, the Cd concentrations in the kernels of the three peanut genotypes were significantly higher in treatment Cd addition than in the control. The Cd accumulation in the kernels of the three peanut genotypes was in the order of Zhanyou 27＞Baisha 1016＞Huayu 22, and the Cd concentrations in the kernels of the peanut genotypes growing on the two soil types were higher on burozem than on fluvo-aquic soil. The values of the Cd bioaccumulation factor for the kernels of the three peanut genotypes were all higher than 1.0 in the control but lower than 1.0 in treatment Cd addition, suggesting that the peanut kernels had a stronger ability in accumulating the Cd from soil, and, when the soil Cd concentration increased, this ability decreased.

Effects of brassinolide on the leaf mitochondria and chloroplast ultrastructure and photosynthesis of cucumber seedlings under hypoxia stress.

LU Xiao-min1,2, SUN Jin1, GUO Shi-rong1, WANG Jun-wei1

2012, 23(08):  2205-2211. 

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A hydroponic experiment was conducted to investigate the effects of 24-epibrassinolide (EBR) on the leaf mitochondria and chloroplast ultrastructure and photosynthesis of cucumber seedlings under hypoxia stress. Under the stress, the apparent quantum yield (AQY) and carboxylation efficiency (CE) decreased significantly, while the light compensation point (LCP), dark breathing rate (R_d), and CO₂ compensation point (CCP) had a significant increase. The application of EBR increased the CE significantly by 29.4%, and decreased the LCP and R_d significantly by 15.0% and 14.4%, respectively. The light response  curve (P_nPPFD) and CO₂ response curve (P_n-C_i) indicated that under hypoxia stress, the increment of net photosynthetic rate (P_n) decreased, while EBR addition enhanced the increment of the P_n. Hypoxia stress damaged the mitochondria and chloroplast ultrastructure, while EBR could alleviate  the damages in chloroplast and mitochondria under hypoxia stress, and keep the leaves in a higher photosynthetic performance.  

Lead adsorption by Trametes gallica, Bacillus cereus,and their co-immobilized biomaterial.

YANG Zhou-ping1, CHEN Ping1, WANG Zhen-yu2, HU Rong1, JING De-jun1, HUANG Qian-ming1

2012, 23(08):  2212-2218. 

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Taking Trametes gallica mycelium pellets, Bacillus cereus, and their coimmobilized biomaterial as bio-adsorbents, this paper studied their Pb²⁺ adsorption under effects of different contact time, medium initial pH value and Pb²⁺ concentration, and bioadsorbent concentration, and compared the infrared spectra of the bio-adsorbents before and after Pb²⁺ absorption. The Pb²⁺ adsorption efficiency of the bio-adsorbents was the highest when the bioadsorbent concentration was 2 g·L^-1, initial pH was 5.0, initial Pb²⁺ concentration was 50 mg·L^-1, and contact time was 1 h, with the Pb2+
biosorption rate being 71.7% for the mycelium pellets of T. gallica, 91.0% for B. cereus, and 96.9% for the co-immobilized biomaterial. The infrared spectra of the bio-adsorbents were mainly consisted of the absorption zones of protein, carbohydrates, and sulphur and phosphorsbased groups, suggesting that hydroxyl, carboxyl, and sulphur and phosphatebased groups played important roles in the Pb²⁺ adsorption by the bio-adsorbents.

Effects of  chlorimuronethyl and urea on soil microbial biomass carbon and nitrogen and soil inorganic nitrogen.

TAN Huan-bo1,2, LI Xin-yu1, ZHANG Hui-wen1, LI Xu1, XU Ming-kai1

2012, 23(08):  2219-2224. 

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A microcosm experiment was conducted to study the effects of  different concentration chlorimuron-ethyl (20, 200, and 2000 μg·kg^-1 soil) and its combination with urea (120 mg·kg^-1 soil) on the dynamic changes of soil microbial biomass carbon and nitrogen and soil nitrate nitrogen and ammonium nitrogen. Applying chlorimuronethyl alone decreased the soil microbial biomass carbon and nitrogen throughout the experiment period (60 days), and the decrement increased with increasing chlorimuronethyl concentration. Chlorimuronethyl had little effects on the soil ammonium nitrogen and nitrite nitrogen in the early period of the experiment, but increased the soil ammonium nitrogen in the midperiod (15 d) and the soil nitrate nitrogen in the late period (after 30 days) significantly. Both urea addition and its combination with chlorimuronethyl increased the soil microbial biomass carbon and nitrogen obviously in a short time, but the effect of combined addition of urea and chlorimuron-ethyl weakened then. Applying urea and its combination with chlorimuronethyl resulted in a lasting increase of soil nitrate nitrogen and ammonium nitrogen.  

Effects of China future land use change on aboveground vegetation biomass.

SUN Xiao-fang1,2, YUE Tian-xiang1

2012, 23(08):  2225-2232. 

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Land use change has significant effects on  vegetation biomass via altering ecosystem structure. By adopting a spatially explicit land use change model, this paper simulated the spatiotemporal pattern of land use change in China till 2030, based on the historical scenario (in this scenario, the land use trend in 1988-2005 was extrapolated to obtain the area of each land use type in the future) and the planned scenario (in this scenario, the area of each land use type in the future was based on the national scale land use planning). On the basis of this simulation and using a biomass density approach, the spatial pattern of vegetation biomass change in China was estimated. The simulation showed that under the historical scenario, the forest area would be decreased but the forest age would be in adverse, and accordingly, the forest biomass density would have an increase. Till 2030, the overall vegetation biomass in China would be 14619 Tg, with an increase of 251.19 Tg as compared to the situation in 2005. Under the planned scenario, the forest area would be increased, and the overall vegetation biomass in 2030 would be 15468 Tg, with an increase of 1100 Tg as compared to the situation in 2005. In the planned scenario, the planted forest area would be larger while the forest age would be younger, resulting in a much lower vegetation biomass density in 2030 than that in the historical scenario, and thus, the China’s vegetation in the planned scenario would have a higher potential to act as a carbon sink.

Quantitative remote sensing retrieval of apple tree canopy reflectance at blossom stage in hilly area.

WANG Ling, ZHAO Geng-xing, ZHU Xi-cun, WANG Rui-yan, CHEN Hong-yan, CHANG Chun-yan

2012, 23(08):  2233-2241. 

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By using the TM and ALOS images with different resolutions at the prosperous blossom stage of apple trees in Qixia City of Shandong Province, and taking the slope aspect coefficient and the ratio of canopy flower to leaf into account, the ground surface reflectance was retrieved through radiometric correction. The canopy reflectance of the apple trees was further retrieved by pixel unmixing method, and the retrieval effect and accuracy were assessed by the comparison of the retrieved reflectance with the measured canopy reflectance and apparent reflectance of 30 sample apple orchards. The results showed that radiometric correction effectively weakened the effects of atmosphere and topography, recovered the ground objects in the shadows, and obviously enhanced the analytical ability of ground surface retrieval reflectance images. Either TM or ALOS images, both the absolute and relative errors between retrieval reflectance and measured reflectance of apple tree canopy were the smallest. The relative errors of all bands were consistent, and its variation trend among the 30 sample apple orchards was also consistent with the measured reflectance, which showed the necessary of pixel unmixing. Moreover, the changes of the reflectance among the sample apple orchards showed similar characteristics when the retrieval method was used for different resolution images. The images with high resolution were more superior, but, because of band limitation, it would be better to integrate the high resolution images with moderate resolution images.  

Ecological risk assessment of dam construction for terrestrial plant species in middle reach of Lancangjiang River, Southwest China.

LI Xiao-yan1, DONG Shi-kui1, LIU Shi-liang1, PENG Ming-chun2, LI Jin-peng1, ZHAO Qing-he1, ZHANG Zhao-ling1

2012, 23(08):  2242-2248. 

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Taking the surrounding areas of Xiaowan Reservoir in the middle reach of Lancangjiang River as study area, and based on the vegetation investigation at three sites including electricity transmission area (site 1), electricitytransfer substation and roadsides to the substation (site 2), and emigration area (site 3) in 1997 (before dam construction), another investigation was conducted on the vegetation composition, plant coverage, and dominant species at the same sites in 2010 (after dam construction), aimed to evaluate the ecological risk of the dam construction for the terrestrial plant species in middle reach of Lancangjiang River. There was an obvious difference in the summed dominance ratio of dominant species at the three sites before and after the dam construction. According the types of species (dominant and non-dominant species) and the changes of plant dominance, the ecological risk (ER) for the plant species was categorized into 0 to IV, i.e., no or extremely low ecological risk (0), low ecological risk (Ⅰ), medium ecological risk (Ⅱ), high ecological risk (Ⅲ), and extremely high ecological risk (Ⅳ). As affected by the dam construction, the majority of the species were at ER Ⅲ, and a few species were at ER Ⅳ. The percentage of the plant species at ER Ⅲ and ER Ⅳ at site  3 was higher than that at sites  1 and  2. The decrease or loss of native plants and the increase of alien or invasive plants were the major ecological risks caused by the dam construction. Effective protection strategies should be adopted to mitigate the ecological risk of the dam construction for the terrestrial plants at species level.

Ecosystem’s soil conservation function and its spatial distribution in Lancang River Basin, Southwest China.

CHEN Long1,2, XIE Gao-di1, PEI Sha1,2, ZHANG Chang-shun1, FAN Na1,2, ZHANG Cai-xia1, LI Shi-mei3

2012, 23(08):  2249-2256. 

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Based on the RUSLE model, this paper analyzed the ecosystem’s soil conservation function and its spatial distribution in Lancang River Basin. This Basin could be one of the regions having the highest ecosystem’s soil conservation capability in China, with an annual ecosystem’s soil conservation amount being 2.36×10¹⁰ t·a^-1 and the soil conservation amount per unit area being 1453.72 t·a^-1 per hectare. The total amounts of the N, P, and K conserved in soils were 5.74×10⁷, 3.07×10⁷, and 3.75×10⁸ t·a^-1, respectively, and presented an increasing trend from upstream to downstream. Among the ecosystems in the Basin, forest ecosystem had the highest soil conservation capability, followed by grassland and farmland, while desert ecosystem had the lowest one. The soil conservation capability of the ecosystems was linearly increased with the increase of vegetation coverage. Averagely, a 10% increment in the vegetation coverage could result in a 35.3% increment in soil conservation capability. To rationally increase the vegetation coverage by reliable ecosystem management based on local conditions would make good effect in preventing soil erosion and maintaining soil nutrients in the Basin.

Calculation model of urban water resources ecological footprint and its application: A case study in Shenyang City of Northeast China.

WANG Jian1, ZHANG Chao-xing1, YU Ying-tan1, LI Fa-yun1, MA Fang2

2012, 23(08):  2257-2262. 

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Water resources ecological footprint can directly reflect the pressure of human social and economic activities to water resources, and provide important reference for the rational utilization of water resources. Based on the existing ecological footprint models and giving full consideration of the water resources need of urban ecological system, this paper established a new calculation model of urban water resources ecological footprint, including domestic water account, process water account, public service water account, and ecological water requirement account. According to the actual situation of Shenyang City, the key parameters of the model were determined, and the water resources ecological footprint and ecological carrying capacity of the City were calculated and analyzed. From 2000 to 2009, the water resources ecological footprint per capita of the City presented an overall decreasing trend, but still had an annual ecological deficit. As compared to that in 2000, the water resources ecological footprint per capita was decreased to 0.31 hm² in 2005, increased slightly in 2006 and 2007, and remained stable in 2008 and 2009, which suggested that the sustainable utilization of water resources in Shenyang City had definite improvement, but was still in an unsustainable development situation.

Ecological effect of different types land consolidation in Hubei Province of China.

GU Xiao-kun

2012, 23(08):  2263-2269. 

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A model for estimating the ecosystem services value under effects of land consolidation was built to quantitatively evaluate the ecological effects of three different types of land consolidation projects in Jianghan Plain, middle hilly region, and western mountainous area of Hubei Province. With the implementation of the projects, the total value of ecosystem services in Jianghan Plain was decreased by 0.3%, among which, the values of food production service and other three services increased but those of water conservation and other four services decreased. In hilly region, the total value of ecosystem services was decreased by 14.6%, with the value of food production service increased by 55.2% and those of other eight services all decreased. In mountainous area, the total value of ecosystem services was decreased by 19.9%, with the value of food production service increased by 24.9% while the values of other eight services all decreased. In the land consolidation in the middle hilly region and western mountainous area of Hubei Province, there was an obvious conversion process ‘from ecology to production’ in the ecosystem services value.

Effects of large bio-manipulation fish pen on community structure of crustacean zooplankton in Meiliang Bay of Taihu Lake.

KE Zhi-xin1, XIE Ping2, GUO Long-gen2, XU Jun2, ZHOU Qiong3

2012, 23(08):  2270-2276. 

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In 2005, a large bio-manipulation pen with the stock of silver carp and bighead carp was built to control the cyanobacterial bloom in Meiliang Bay of  Taihu Lake. This paper investigated the seasonal variation of the community structure of crustacean zooplankton and the water quality within and outside the pen. There were no significant differences in the environmental parameters and phytoplankton biomass within and outside the pen. The species composition and seasonal dynamics of crustacean zooplankton within and outside the pen were similar, but the biomass of crustacean zooplankton was greatly suppressed by silver carp and bighead carp. The total crustacean zooplankton biomass and cladocerans biomass were significantly lower in the pen (P<0.05). In general, silver carp and bighead carp exerted more pressure on cladoceran species than on copepod species. A distinct seasonal succession of crustacean zooplankton was observed in the Bay. Many crustacean species were only dominated in given seasons. Largesized crustacean (mainly Daphnia sp. and Cyclops vicnus) dominated in winter and spring, while smallsized species (mainly Bosmina sp., Ceriodaphnia cornuta, and Limnoithona sinensis) dominated in summer and autumn. Canonical correspondence analysis showed that water transparency, temperature, and phytoplankton biomass were the most important factors affecting the seasonal succession of the crustacean.  

A comparison of zooplankton communities collected by two types of nets with different mesh sizes in Xiangshan Bay of Zhejiang, East China.

ZHU Yi-feng, WANG Yin, LIN Xia, WU Yan-ping, ZHAO Jin-long, YAN Xiao-jun

2012, 23(08):  2277-2286. 

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In March (spring), July (summer), September (autumn), and December (winter) 2010, the zooplanktons at six stations in Xiangshan Bay were sampled simultaneously by the nets with a mesh size of 505 μm (net type Ⅰ) and of 160 μm (net type Ⅱ), and each sampling had two replicates. The spatiotemporal differences in the zooplanktons communities collected by the two types of nets were compared. There existed great differences in the species number, abundance, biomass, dominant species, and community pattern between the zooplanktons collected by the two types of nets. The species number, average abundance, and average biomass of the zooplanktons collected by net type Ⅰ (61 species including larvae, 139.0 ind·m^-3, and 86.1 mg·m^-3, respectively) were siginificantly lower than those collected by net Ⅱ (84 species, 3780.2 ind·m^-3, and 191.1 mg·m^-3, respectively). In the dominant species, except for Acartia pacifica and Centropages mcmurrichi, the others were completely different between the zooplanktons collected by the two types of nets. In the zooplanktons collected by net type Ⅰ, no species dominating over the year was found, while in the zooplanktons collected by net type Ⅱ, Paracalanus aculeatus and Copepods larva were dominant over the year. The similarity analysis (ANOSIM) and nonmetric multidimensional scaling (nMDS) ordination revealed that the community pattern of the zooplanktons collected by the two types of nets had significant spatiotemporal difference, and the community pattern of the zooplanktons collected by net type Ⅰ was more discrete than that of the zooplanktons collected by net type Ⅱ. The analysis of similarity percentage (SIMPER) further revealed that the average dissimilarity of the spatiotemporal difference in the community pattern between the zookplanktons collected by the two types of nets exceeded 75%, and the main discriminating species causing this dissimilarity were Paracalanus aculeatus, Copepods larva, Paracalanus crassirostris, and Oithona brevicornis, all of which were the dominant species of the zooplanktons collected by net type Ⅱ. In a word, the zooplanktons collected by net type Ⅱ were more representative for the investigation of the zooplanktons in Xiangshan Bay.

Variations of zooplankton’s community structure in reclaimed waters of Nanhui east tidal flat of Shanghai, East China.

LI Qiang1,2, MA Chang-an1, LU Wei-wei1, TIAN Wei1, YU Ji1, ZHAO Yun-long1

2012, 23(08):  2287-2294. 

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From October 2010 to July 2011, an investigation was conducted on the zooplankton communities in reclaimed and natural waters in Nanhui east tidal flat to study the seasonal variations of the zooplankton’s species composition, abundance, biomass, dominant species, and biodiversity, aimed to explore the differences in the zooplankton’s community structure within and outside the reclaimed waters and the relationships of the community structure with several indispensable environmental factors such as water salinity, water temperature, and human activities. A total of 30 zooplankton species were identified, among which, 24 species were in reclaimed waters and dominated by rotifers, and 14 species were in natural waters and dominated by copepods. The average abundance of the zooplankton was obviously higher in reclaimed waters than in natural waters, but the average biomass was in adverse. The dominant species in reclaimed waters were freshwater species, such as Brachionus angularis, Bcalyciflorus, and Mesocyclops leuckarti, while those in natural waters were brackish species, such as Sinocalanus sinensis, Schmackeria poplesia, and Tortanus vermiculus. Both in reclaimed and in natural waters, the dominant species had seasonal alternation. The Shannon index (H) and Pielou evenness index (J) of the zooplankton communities were higher in natural waters, but the Margalef species richness (d) and simplicity index (C) were higher in reclaimed waters. Cluster analysis and MDS evaluation indicated that there was an obvious difference in the community structure of zooplankton between reclaimed and natural waters. Reclamation could be the primary cause for the variations of the zooplankton’s community structure in reclaimed waters, and environmental factors such as water salinity and tidal power also contributed to the variations.

Effects of dissolved organic matter on copper absorption by ryegrass.

TANG Chao1,2, WANG Bin1, LIU Man-qiang1, HU Feng1, LI Hui-xin1, JIAO Jia-guo1

2012, 23(08):  2295-2299. 

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In this study, dissolved organic matter (DOM) was extracted from earthworm casts and from the cattle manure with which the earthworms were fed, and a water culture experiment was conducted to study the effects of the DOM on the copper (Cu²⁺) absorption by ryegrass in the presence of different concentration Cu²⁺(0, 5 and 10 mg ·L^-1). With the increasing concentration of Cu²⁺ in the medium, there was a gradual decrease in the dry mass of ryegrass shoots and roots and in the root length, surface area, volume, and tip number. In the presence of medium Cu²⁺, DOM increased the biomass of shoots and roots and the root length, surface area, volume, and tip number significantly. DOM reduced the Cu²⁺concentration in roots, promoted the Cu²⁺ translocation from roots to shoots, and significantly increased the Cu²⁺ accumulation in shoots. The DOM from earthworm casts had better effects than that from cattle manure, and high concentration DOM had better effects than low concentration DOM.  

Degradation pathways and main degradation products of tetracycline antibiotics: Research progress.

LI Wei-ming, BAO Yan-yu, ZHOU Qi-xing

2012, 23(08):  2300-2308. 

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Tetracycline antibiotics (TCs) can produce a series of abiotic degradation reactions in the process of production and storage, and some of the degradation products have lower antibacterial activity but higher toxicity, as compared to the parent antibiotics. TCs can enter the environment via the disposal of livestock and poultry wastes, and then degrade in one or more ways according to the external conditions. Besides abiotic degradation, bio-degradation also happens. This paper reviewed the degradation pathways and main degradation products of TCs in different ecological environments, and discussed the future research directions, aimed to provide valuable reference for the ecological risk assessment of the antibiotics.

Methanotrophs and their applications in environment treatment: A review.

WEI Su-zhen

2012, 23(08):  2309-2318. 

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Methanotrophs can oxidize methane, playing an important role in regulating methane emission, and gaining increasing attention by the researchers around the world. Two biological pathways are involved in methane oxidation, i.e., anaerobic oxidation and aerobic oxidation, which are governed by anaerobic and aerobic methanotrophs, respectively. In this paper, the research advances about methanotrophs were summarized, with the focus on the phylogeny and taxonomy of methanotrophs, the key enzymes responsible for the aerobic oxidation of methane, the microorganisms involved in the anaerobic oxidation of methane, and the mechanisms of microbial methane consumption. The application prospects of the two methane oxidizers in greenhouse gases removal, pollutants degradation, biological denitrification, and recovery of metals and sulfur compounds were also analyzed.

Environmental behavior and ecological effect of polydimethylsiloxane: A review. 

YANG Shang-yuan, LI Xin, YANG Jia, SHEN Chao-feng, YU Hua-dong, LU Kang

2012, 23(08):  2319-2324. 

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Polydimethylsiloxane (PDMS) is widely used in industrial products, medical and health care products, and personal care products. In the treatment process of sewage, PDMS can be hardly biodegraded but enter the environment mainly through the discharge of excess sludge, and only a small amount of PDMS adsorbed on the suspended solids or sludge particle surface is discharged into water body and sediment with treated sewage. There is no enough evidence to verify that PDMS can vertically migrate in sediment. The degradation of PDMS in sediment is very slow, but PDMS can be degraded in different types of soils. PDMS has less risk to aquatic ecosystem, and no apparent acute toxicity to benthos. In soil environment, PDMS and its degradation products have no significant effects on the soil microorganisms, soil animals, and crops. Though a few studies indicated that PDMS and its degradation products have relatively low ecological toxicity in various environments, it is still very important to clarify the potential threat of PDMS to the environment because of the increasingly large number of PDMS being produced and used.