Table of Content

18 October 2012, Volume 23 Issue 10

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Articles

Effects of light quality on the seed germination of main tree species in a secondary forest ecosystem of Northeast China.

ZHANG Min1,2,3, ZHU Jiao-jun1,2, YAN Qiao-ling1,2,3

2012, 23(10):  2625-2631. 

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This paper explored the effects of light quality on the seed germination of five dominant tree species (Larix kaempferi, Phellodendron amurense, Acer mono, Fraxinus mandshurica, andPinus koraiensis) in a secondary forest ecosystem of Northeast China, based on the experiments with the seeds of the five tree species in laboratory and those of the P. koraiensis and L. kaempferi in the field. Four treatments of different light quality were designed in laboratory (taking dark as the control), and three treatments of R/FR (the ratio of red light and far red light intensity) were installed in the field. The laboratory experiment showed that light quality had less effect on the seed germination of L. kaempferi, but the seed germination rates of the other four tree species were significantly different under the treatments of different light quality. P. amurense had the highest seed germination rate under white light, whereas A. mono, F. mandshurica, and P. koraiensis had the highest one under the alternative irradiation with red light and far red light (R-FR-R). In consistence with the results in laboratory, the seed germination rate of P. koraiensis in the field decreased with decreasing R/FR ratio, while that of L. kaempferi was less affected. Under natural condition, the R-FR-R fluctuated with the activity of sun-fleck, and the seed germination patterns of A. mono, F. mandshurica, and P. koraiensis could be the adaptation to the sunfleck environment in forest stand. The germination of large seeds was significantly affected by light quality.

Relationships between soil moisture and needle-fall in Masson pine forests in acid rain region of Chongqing, Southwest China.

WANG Yi-hao1,2, WANG Yan-hui1, LI Zhen-hua1, YU Peng-tao1, XIONG Wei1, HAO Jia1, DUAN Jian3

2012, 23(10):  2632-2640. 

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From March 2009 to November 2011, an investigation was conducted on the spatiotemporal variation of soil moisture and its effects on the needle-fall in Masson pine (Pinus massoniana) forests in acid rain region of Chongqing, Southeast China，with the corresponding soil moisture thresholds determined. No matter the annual precipitation was abundant, normal or less than average, the seasonal variation of soil moisture in the forests could be obviously divided into four periods, i.e., sufficient (before May), descending (from June to July), drought (from August to September), and recovering (from October to November). With increasing soil depth, the soil moisture content increased after an initial decrease, but the difference of the soil moisture content among different soil layers decreased with decreasing annual precipitation. The amount of monthly needle-fall in the forests in growth season was significantly correlated with the water storage in root zone (0-60 cm soil layer), especially in the main root zone (20-50 cm soil layer). Soil field capacity (or capillary porosity) and 82% of field capacity (or 80% of capillary porosity) were the main soil moisture thresholds affecting the litter-fall. It was suggested that in acid rain region, Masson pine forest was easily to suffer from water deficit stress, especially in dry-summer period. The water deficit stress, together with already existed acid rain stress, would further threaten the health of the Masson forest.

Content and distribution of active components in cultivated and wild Taxus chinensisvar. mairei plants.

YU Shao-shuai1, SUN Qi-wu2, ZHANG Xiao-ping1, TIAN Sheng-ni3, BO Pei-lei1

2012, 23(10):  2641-2647. 

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Taxus chinensis var. mairei is an endemic and endangered plant species in China. The resources of T. chinensis var. mairei have been excessively exploited due to  its anti-cancer potential, accordingly, the extant T. chinensis var. mairei population is decreasing. In this paper, ultrasonic extraction and HPLC were adopted to determine the contents of active components paclitaxel, 7-xylosyltaxol and cephalomannine in cultivated and wild T. chinensis var. mairei plants, with the content distribution of these components in different parts of the plants having grown for different years and at different slope aspects investigated. There existed obvious differences in the contents of these active components between cultivated and wild T. chinensis var. mairei plants. The paclitaxel content in the wild plants was about 0.78 times more than that in the cultivated plants, whereas the 7-xylosyltaxol and cephalomannine contents were slishtly higher in the cultivated plants. The differences in the three active components contents between different parts and tree canopies of the plants were notable, being higher in barks and upper tree canopies. Four-year old plants had comparatively higher contents of paclitaxel, 7xylosyltaxol and cephalomannine (0.08, 0.91 and 0.32 mg·g^-1, respectively), and the plants growing at sunny slope had higher contents of the three active components, with significant differences in the paclitaxel and 7-xylosyltaxol contents and unapparent difference in the cephalomannine content of the plants at shady slope. It was suggested that the accumulation of the three active components in T. chinensis var. mairei plants were closely related to the sunshine conditions. To appropriately increase the sunshine during the artificial cultivation of T. chinensis var. mairei would be beneficial to the accumulation of the three active components in T. chinensis var. mairei plants.  

Effects of cutting on the dominant and subdominant plant species in a Stipa krylovii steppe of Inner Mongolia.

LI Xin1,2,3, SHI Feng-ling1, GAO Yan2, ZHAO Ming-xu3, LI Ling-hao2

2012, 23(10):  2648-2654. 

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Based on the long-term cutting experiment, this paper analyzed the responses of the aboveground biomass of five dominant and subdominant plant species and the community stability in a Stipa krylovii steppe of Inner Mongolia to various cutting height. Cutting with a stubble height of >10 cm had slight effects on the aboveground biomass of the five species. Cutting with a stubble height of 10 cm benefited the growth of Artemisia frigida but made against the growth of Stipa krylovii. Cleistogenes squarrosa at the stubble height of 2 cm performed best, and Carex korshinskyi at the stubble height of 5 cm contributed most to the community, with the biomass positively correlated with the cutting years. Potentilla acaulis growth was detrimentally affected at the stubble heights of 2 and 15 cm. Overall, perennial species with higher plant height and stronger competitive ability were more tolerant to disturbances, and a minimum cutting height of 10 cm should be applied to maintain a high stability of the steppe ecosystem.

Inhibitory effect of DMPP on soil nitrification as affected by soil moisture content, pH  and organic matter.

XUE Yan1,2, WU Zhi-jie1, ZHANG Li-li1, GONG Ping1,2, DONG Xin-xin1,2, NIE Yan-xia1,2

2012, 23(10):  2663-2669. 

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A laboratory incubation test with meadow brown soil was conducted to study the inhibitory effect of 3,4-dimethylpyrazole phosphate (DMPP) on soil nitrification as affected by soil moisture content (40%, 60% and 80% of the maximum field capacity), pH (4, 7 and 10), and organic matter (retained and removal). With the decrease of soil moisture content, the degradation of DMPP in soil tended to slow down, and the oxidation of soil NH₄⁺ was more inhibited. At pH 10, more DMPP was remained in soil, and had the greatest inhibitory effect; at pH 7 and pH 4, the DMPP was lesser remained, with a smaller inhibitory effect. The removal of organic matter prolonged the remaining time of DMPP in soil, and decreased the apparent soil nitrification rate significantly.

Effects of land use type and incubation temperature on soil nitrogen transformation and greenhouse gas emission.

LANG Man1,2, LI Ping1,2, ZHANG Xiao-chuan3

2012, 23(10):  2670-2676. 

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A laboratory experiment with the soil samples collected from China and Canada was conducted to study the effects of land use type (forestland vs. grassland) and incubation temperature (10  ℃ vs. 15 ℃) on the soil nitrification, nitrogen mineralization, and N₂O and CO₂ emissions under aerobic condition. As compared with forestland soils, grassland soils had higher nitrification rate and N₂O emission, with the highest nitrification rate in China grassland soil. At 10 and 15 ℃, the average net nitrification rate of China grassland soil was 2.10 and 2.86 mg N·kg^-1·d^-1, and the cumulative N₂O emission in 15 incubation days was 10.2 and 15.4 μg N₂ON·kg^-1, respectively. Soil pH was the main factor affecting the nitrification rate and N₂O emission, and there existed significant positive correlations between the soil pH and the nitrification rate and N₂O emission. Forestland soils had higher nitrogen mineralization rate and CO₂ emission than grassland soils, and China forestland soil had the highest nitrogen mineralization rate, with the average net mineralization rate at 10 and 15 ℃ being 3.08 and 2.87 mg N·kg^-1·d^-1, respectively. The CO₂emission was the highest in Canada forestland soil, and the cumulative CO₂ emission in 15 incubation days at 10 and 15 ℃ was 314 and 370 mg CO₂C·kg^-1, respectively. The soil organic carbon and soluble organic carbon contents had significant positive correlations with the soil nitrogen mineralization rate and CO₂ emission, respectively, whereas the increasing soil temperature promoted the nitrification in grassland soils and the N₂O emission from forestland soils and grassland soils. The same pronounced effects of increasing temperature were also found on the CO₂ emission from forestland soils.

Effects of land use type on spatiotemporal distribution of soil nutrients in Dianchi watershed, Yunnan Province of Southwest China.

CHEN Chun-yu, HE Shu-zhuang, HU Bin, LU Wen-long

2012, 23(10):  2677-2684. 

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Surface soil samples were monthly collected from six land use types (abandoned greenhouse field, forest land, sloped farmland, table land, flat vegetable land and greenhouse field) in Dianchi watershed of Yunnan to determine the soil pH and the contents of soil organic matter (OM), total nitrogen (TN), and total phosphorus (TP), aimed to understand the effects of different land use types on the spatiotemporal distribution of the soil nutrients. The soil pH, SOM, TN and TP, contents, and soil C/N differed significantly with soil land use types. The soil pH was in the order of abandoned greenhouse field > flat vegetable land > greenhouse field > table land > sloped farmland > forest land; the OM content was in the sequence of abandoned greenhouse field > flat vegetable land > greenhouse field > sloped farmland > forest land > table land; the TN content was  in the order of greenhouse field > flat vegetable land > abandoned greenhouse field > sloped farmland > table land > forest land; the TP content was  in the order of flat vegetable field > greenhouse field > abandoned greenhouse field > sloped farmland > table land > forest land; and the C/N ratio was in the sequence of forest land > sloped farmland > flat vegetable plot > table land > abandoned greenhouse field > greenhouse field. The OM, TN and TP contents were affected by fertilization, irrigation, field cultivation and season. All the test parameters had the highest values in rainy season, which could be related to the local top-dressing habits. There were significant positive correlations among the  TN, TP and OM under all the land use types. In greenhouse field and abandoned greenhouse field, due to the severe human disturbances, the soil pH and OM, TN and TP contents were obviously higher than those in forestland and table land.

Chemical properties and enzyme activities of rhizosphere and non-rhizosphere soils under six Chinese herbal medicines on Mt. Taibai of Qinling Mountains, Northwest China.

MENG Ling-jun1, GENG Zeng-chao1,2, YIN Jin-yan1, WANG Hai-tao1, JI Peng-fei1

2012, 23(10):  2685-2692. 

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This paper studied the chemical properties and enzyme activities of rhizosphere and non-rhizosphere soils in different habitats of six Chinese herbal medicines, including Pyrola decorata, Cephalotaxus fortunei, Polygonatum odoratum, Potentilla glabra, Polygonum viviparum, and Potentilla fruticosa, on the Mt. Taibai of Qinling Mountains. In the rhizosphere soils of the herbs, the contents of soil organic matter, total nitrogen, available nitrogen, and available phosphorus and the soil cation exchange capacity (CEC) were higher, presenting an obvious rhizosphere aggregation, and the soil enzyme activities also showed an overall stronger characteristics, compared with those in non-rhizosphere soils. The soil organic matter, total nitrogen, and total phosphorus contents in the rhizosphere soils had significant positive correlations with soil neutral phosphatase activity, and the soil CEC had significant positive correlations with the activities of soil neutral phosphatase and acid phosphatase. In the non-rhizosphere soils, the soil organic matter and total nitrogen contents had significant positive correlations with the activities of soil urease, catalase and neutral phosphatase, and the soil CEC showed a significant positive correlation with the activities of soil urease, catalase, neutral phosphatase and acid phosphatase. The comprehensive fertility level of the rhizosphere soils was higher than that of the non-rhizosphere soils, and the rhizosphere and non-rhizosphere soils of P. fruticosa, P. viviparum, and P. glabra had higher comprehensive fertility level than those of P. decorata, P. odoratum and C. fortunei. In the evaluation of the fertility levels of rhizosphere and non-rhizosphere soils under the six Chinese herbal medicines, soil organic matter content and CEC played important roles, and soil neutral phosphatase could be the preferred soil enzyme indicator.  

Effects of applying endophytic fungi on the soil biological characteristics and enzyme activities under continuously cropped peanut.

WANG Hong-wei1, WANG Xing-xiang2，3，4, LU Li-xin1, XIAO Yi1, DAI Chuan-chao1

2012, 23(10):  2693-2700. 

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A pot experiment was conducted to investigate the effects of applying endophytic fungi Phomopsis liquidambari strain B3, Phomopsis sp. strain NJ4.1, and Ceratobasidum stevensii strain B6 on the soil biological characteristics and enzyme activities under continuously cropped peanut at its different growth stages.  Compared with the control, applying B3 increased the peanut yield significantly by 19.8%, and applying NJ4.1, B3 and B6 increased the peanut nodule number significantly by 20.4%, 29.3% and 27.6%, respectively. In the three treatments of applying endophytic fungi, the average population of soil bacteria and actinomycetes in the whole growth period of peanut was higher than that of the control, and the soil microbial biomass carbon was significantly greater at germination and seedling stages. The soil microbial biomass nitrogen increased at germination stage, but decreased at flowering stage. The DGGE analysis indicated that at flowering stage, the soil bacteria and fungi in treatment B3 had the largest band number and diversity. From germination stage to maturing stage, the three treatments of applying endophytic fungi had higher activities of soil invertase and catalase than the control, but less difference in soil urease activity. It was suggested that applying endophytic fungi could improve the peanut continuous cropping soil environment, and applying B3 had the best effect.  

Effects of applying sewage sludge on chemical form distribution and bioavailability of heavy metals in soil.

SONG Lin-lin, TIE Mei, ZHANG Zhao-hong, HUI Xiu-juan, JING Kui, CHEN Zhong-lin, ZHANG Ying

2012, 23(10):  2701-2707. 

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A pot experiment was conducted to study the effects of applying sewage sludge on the chemical form distribution of heavy metals (Cd, Pb, Cu and Zn) in soil and the transfer and accumulation of the heavy metals in soil-plant (ryegrass) system. With the application of sewage sludge, the contents of bioavailable Cd and Zn in soil increased significantly but that of  bioavailable Pb in soil had a significant decrease, and the content of residual form Pb in soil increased by 33.3%-74.5%,  compared with CK. When the application rate of sewage sludge was 50% (M/M) of soil, the contents of  exchangeable and reducible Cu in soil only occupied 0.7% and 02% of the  total Cu respectively. The application of sewage sludge promoted the Cd, Cu and Zn absorption while inhibited the Pb absorption by ryegrass. Multiple linear regression analysis showed that the  Cd, Zn and Cu contents in ryegrass  were positively correlated with the  reducible Cd and Zn and oxidizable Cu contents in soil, respectively, and  Pb content in ryegrass was highly correlated with the soil exchangeable and oxidizable Pb contents. After planting ryegrass, the oxidizable Cd and Cu in rhizosphere soil were transformed into exchangeable Cd and residual form Cu, respectively, the exchangeable and reducible Zn transformed into oxidizable Zn, whereas the bioavailability of Pb was less affected.  

Degradation and bioaccumulation characteristics of ciprofloxacin in soil-vegetable system.

XIAO Qiu-mei1,2,3, WANG Jian-wu1,2,3, TANG Yi-ling1,2,3

2012, 23(10):  2708-2714. 

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A pot experiment was conducted to investigate the effects of applying ciprofloxacin (CIP) on the growth of flowering Chinese cabbage (Brassica campestris), radish (Raphanus sativus), tomato (Solanum lycopersicum) and long bean (Vigna unguiculata), the bioaccumation of CIP in the vegetables, and the degradation of the antibiotics in soil. The results showed that applying 5, 30 and 75 mg·kg^-1 of CIP had no significant effects on the plant biomass of flowering Chinese cabbage, tomato and long bean, but the high concentration of CIP (≥30 mg·kg^-1) inhibited the radish growth significantly. The degradation of CIP in soil was fast at beginning, but slowed down gradually since then. The DT₅₀ and DT₉₀ of CIP in long bean soil were 18.3-43.9 d and 260-738 d, respectively. The CIP could be absorbed by the roots of all the four vegetables and allocated to their aboveground parts, and the CIP residues in the vegetables in creased with the concentration of CIP in soil. The CIP concentration in flowering Chinese cabbage roots was higher than that in the cabbage aboveground parts, that in radish showed a higher concentration in aboveground parts than in roots, and the CIP concentration in tomato and long bean was in the same order of root＞stem＞leaf.

Characteristics of soil microbial biomass carbon and soil water soluble organic carbon in the process of natural restoration of Karst forest.

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

2012, 23(10):  2715-2720. 

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By the method of taking space instead of time, an incubation test was conducted to study the characteristics of soil microbial biomass carbon and water soluble organic carbon in the process of natural restoration of Karst forest in Maolan Nature Reserve, Guizhou Province of Southwest China. The soil microbial biomass carbon content and soil basal respiration decreased with increasing soil depth but increased with the process of the natural restoration, soil microbial quotient increased with increasing soil depth and with the process of restoration, and soil water soluble organic carbon content decreased with increasing soil depth. In the process of the natural restoration, surface soil water soluble organic carbon content increased, while sublayer soil water soluble organic carbon content decreased after an initial increase. The ratio of soil water soluble organic carbon to total soil organic carbon increased with increasing soil depth but decreased with the process of restoration. Soil quality increased with the process of restoration. Also, the quality and quantity of soil organic carbon increased with the process of restoration, in which, soil microbial biomass carbon content had the greatest change, while soil water soluble organic carbon content had less change.

Effects of revegetation on organic carbon storage in deep soils in hilly Loess Plateau region of Northwest China.

ZHANG Jin1, XU Ming-xiang2,3, WANG Zheng2, MA Xin-xin3, QIU Yu-jie2

2012, 23(10):  2721-2727. 

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Taking the Robinia pseudoacacia woodlands, Caragana korshinskii shrublands, and abandoned croplands with different years of revegetation in the hilly Loess Plateau region of Northwest China as test objects, this paper studied the profile distribution and accumulation dynamics of organic carbon storage in deep soil (100-400 cm), with those in 0-100 cm soil profile as the control. In 0-100 cm soil profile, the organic carbon storage decreased significantly with the increase of soil depth; while in deep soil, the organic carbon storage had a slight fluctuation. The total organic carbon storage in 100-400 cm soil profile was considerably high, accounting for approximately 60% of that in 0-400 cm soil profile. The organic carbon storage in 80-100 cm soil layer had a significant linear correlation with that in 100-200 and 200-400 cm soil layers, and among the organic carbon storages in the five layers in 0-100 cm soil profile, the organic carbon storage in 80-100 cm soil layer had the strongest correlation with that in 100-400 cm soil profile, being able to be used to estimate the organic carbon storage in deep soil in this region. The organic carbon storage in 0-20 cm soil layer in the three types of revegetation lands was significantly higher than that in slope croplands, but the organic carbon storage in deep soil had no significant difference among the land use types. The orga〖JP2〗nic carbon storage in deep soil  increased with the increasing years of revegetation. In R. pseudoacacia woodlands and C. korshinskii shrub lands, the average increasing rate of the organic carbon storage in 100-400 cm soil layer was 0.14 and 0.19 t·hm^-2·a^-1, respectively, which was comparable to that in the 0-100 cm soil layer in C. korshinskii shrublands. It was suggested that in the estimation of the soil carbon sequestration effect of revegetation in hilly Loess Plateau region, the organic carbon accumulation in deep soil should be taken into consideration. Otherwise, the effect of revegetation on soil carbon sequestration would be significantly underestimated.

Allelopathic effects of Streptomyces sp.6803 on plants.

SONG Yuan-yuan1,2,3, HUANG Ke3，4, SHI Mu-biao4, CHEN Min1,2,3, ZENG Ren-sen1,2,3

2012, 23(10):  2728-2736. 

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Streptomyces  can produce an overwhelming majority of known antibiotics and several biologically active compounds, but whether Streptomyces can display allelopathic effects on higher plants is largely unknown. In this study, seven actinomyces strains isolated from soils showed inhibitory effect on plant seedlings growth, among which, Streptomyces sp. 6803 had strong capability in inhibiting the seedlings growth of Brassica campestris and Echinochloa crusgalli in both solid and liquid cultures. The dilute solution (×5) of fermented broth inhibited the seedlings growth of B. campestris and E. crusgalli by 60.7% and 61.3%, respectively. Based on the morphological and physiologicalbiochemical characteristics and 16S rRNA sequencing, Streptomyces sp. 6803 was identified as Streptomyces arenae, with the 16S rRNA sequence identity being 99.28%. Ultraviolet radiation and diethyl sulfate (DES) were used to produce mutants to enhance the allelopathic potential of this strain. After 80 and 100 seconds of ultraviolet radiation, the dilute solution (×10) of fermented broth of obtained mutants UV8024 and UV100-2 showed 37.5% and 38.1% higher inhibition effect on the root growth of B.campestris seedlings, respectively,  compared with  the control. The mutant D507 obtained through 1% DES treatment for 50 min showed 29.8% higher inhibition effect on the root growth of B. campestris seedlings. This study showed that Streptomyces sp. 6803 had allelopathic effect on higher plants, and it was possible to enhance the allelopathic potential of the strain via mutation breeding.

Effects of different sowing dates and  low-light stress at heading stage on the physiological characteristics and grain yield of hybrid rice.

SUN Yuan-yuan1,2, SUN Yong-jian2,3, CHEN Lin4, XU Hui2,3, MA Jun2,3

2012, 23(10):  2734-2744. 

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Hybrid rice Chuanxiang 9838 with medium shade-endurance was taken as the test material to investigate the effects of different sowing dates and  low-light stress at heading stage on the flag leaf photosynthetic rate (P_n), osmotic regulators, antioxidant enzyme activities  and the grain yield of hybrid rice. Sowing date and  lowlight stress at heading stage had significant effects on the flag leaf P_n and antioxidant enzyme activities and plant dry matter accumulation at heading stage and the grain yield. With the delay of sowing date, the whole period of rice growth and development shortened notably, and the grain yield decreased to different degrees.  Compared with the control, short-term slight low-light stress (20% shading) at heading stage could relieve the harms from high temperature and strong light, and further, relieve the decrease of flag leaf P_n and plant dry matter accumulation at heading stage, adjust the flag leaf antioxidant enzyme activities, and moderately improve the seed setting rate. However, short-term medium low-light stress (40% shading) and serious lowlight stress (60% shading) were not beneficial to the rice growth. Correlation analysis indicated that the flag leaf P_n, malondialdehyde (MDA) content, and superoxide dismutase (SOD) were more sensitive to the sowing date and  low-light stress at heading stage, and there existed a highly significant positive correlation between the flag leaf P_n at initial heading stage  (1-5 d) and the plant dry matter accumulation at late heading stage and grain yield.

Effects of irrigation time on the growth and water- and fertilizer use efficiencies of winter wheat.

DANG Jian-you, PEI Xue-xia, WANG Jiao-ai, ZHANG Jing, CAO Yong, ZHANG Ding-yi

2012, 23(10):  2745-2750. 

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A field experiment was conducted to study the effects of irrigation time before wintering (November 10th, November 25th, and December 10th) and in spring (March 5th, re-greening stage; and April 5th, jointing stage) on the growth, dry matter translocation, water use efficiency (WUE), and fertilizer use efficiency (FUE) of winter wheat after returning corn straw into soil. The irrigation time before wintering mainly affected the wheat population size before wintering and at jointing stage, whereas the irrigation time in spring mainly affected the spike number, grain yield, dry matter translocation, WUE, and FUE. The effects of irrigation time before wintering to the yield formation of winter wheat were closely related to the irrigation time in spring. When the irrigation time in spring was at re-greening stage, the earlier the irrigation time before wintering, the larger the spike number and the higher the grain yield; when the irrigation time in spring was at jointing stage, the delay of the irrigation time before wintering made the spike number and grain yield decreased after an initial increase, the kernel number per plant increased, while the 1000-kernel mass was less affected. The WUE, nutrition uptake, and FUE all decreased with the delay of the irrigation time before wintering, but increased with the delay of the irrigation time in spring. Therefore, under the conditions of returning corn straw into soil and sowing when the soil had enough moisture, to properly advance the irrigation time before wintering could make the soil more compacted, promote the tillering and increase the population size before winter, and in combining the increased irrigation at jointing stage, could control the invalid tillering in early spring, increase the spiking rate, obtain stable kernel mass, and thus, increase the WUE and FUE, realizing water-saving and high efficiency for winter wheat cultivation.

Effects of irrigation mode and N application rate on cotton field fertilizer N use efficiency and N losses.

WANG Xiao-juan, WEI Chang-zhou, ZHANG Jun, DONG Peng, WANG Juan, ZHU Qi-chao, WANG Jin-xin

2012, 23(10):  2751-2758. 

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A field experiment was conducted to study the effects of different irrigation modes (drip irrigation and furrow irrigation) and different N application rates (0, 240, 360 and 480 kg N·hm^-2) on the fertilizer N use efficiency and N losses in a cotton field in Xinjiang, Northwest China. The main N cycling pathways, such as the N uptake by cotton plant, NO₃^--N residual in soil, NH₃ volatilization, NO₃^-_-N leaching, and nitrificationdenitrification, were quantitatively monitored. Compared with furrow irrigation, drip irrigation increased the seed cotton yield, plant N uptake, and fertilizer N use efficiency significantly. The NO₃^--N residual in soil was significantly greater under furrow irrigation than under drip irrigation. With the application of fertilizer N, the N loss from NH₃ volatilization under drip irrigation occupied 0.06%-0.14% of applied N, and was significantly greater than that under furrow irrigation. The N loss from NO₃^--N leaching under drip irrigation and furrow irrigation was 4.4% and 8.8% of the applied N, respectively.  Compared with furrow irrigation, drip irrigation could significantly decrease the NO₃^--N leakage rate in leakage water. The nitrification-dinetrification loss under drip irrigation and furrow irrigation was 17.9% and 16.8% of the applied N, respectively. It was suggested that NO₃^--N leaching and nitrification-denitrification were the main N losses in the cotton fields of Xinjiang.

Fate and balance of bulk blending controlled release fertilizer nitrogen under continuous cropping of mustard.

ZHANG Pan-pan, FAN Xiao-lin

2012, 23(10):  2759-2765. 

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Under the conditions of applying water soluble fertilizer and its bulk blending with controlled release fertilizer (BB-CRF), and by using micro-lysimeter, this paper quantitatively studied the nitrogen (N) uptake by mustard, the soil N losses from N₂O emission, leaching and others, and the N residual in soil in  three rotations of continuously cropped mustard. In the treatment of BB-CRF with 25% of controlled release nitrogen, the N uptake by mustard increased with rotations, and the yield by the end of the experiment was significantly higher than that in the treatment of water soluble fertilizer. The cumulated N₂O emission loss and the Neaching loss were obviously higher in treatment water soluble fertilizer than in treatment BB-CRF. NO₃^--N was the primary form of N in the leachate. In relative to water soluble fertilizer, BB-CRF altered the fates of fertilizer nitrogen, i.e., the N uptake by mustard and the N residual in soil increased by 75.4% and 76.0%, and the N leaching loss and other apparent N losses decreased by 27.1% and 66.3%, respectively. The application of BB-CRF could be an effective way to reduce the various losses of fertilizer N while increase the fertilizer N use efficiency, and the controlled release fertilizer is the environmentally friendly fertilizer with the property of high N use efficiency.

Effects of nitrogen deposition on  leaf physiological and ecological characteristics of Lindera aggregata seedlings.

WANG Qiang1,2, JIN Ze-xin2, PENG Li-qiong2,3

2012, 23(10):  2766-2772. 

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From June 2010 to July 2011, a pot experiment was conducted to explore the effects of nitrogen deposition on the leaf physiological and ecological characteristics of Lindera aggregate seedlings. Three levels of NH₄NO₃, i.e., lowN (2 g·m^-2·a^-1), mediumN (8 g·m^-2·a^-1), and highN (32 g·m^-2·a^-1), were added to simulate nitrogen deposition, and the seedling leaf photosynthesis, relative chlorophyll content, chlorophyll fluorescence parameters, membrane lipid peroxidation, and antioxidant enzyme activities were determined. After oneyear treatment, the daily mean values of the net photosynthetic rate (P_n) and the maximum net photosynthetic rate (P_{n max}) at low, medium and high levels of NH₄NO₃ addition were 47.0%, 117.8% and 41.2%, and 82;6%, 191.3% and 152.2% higher than those of the control (no NH₄NO₃ addition), respectively, with the highest values at medium level of NH₄NO₃ addition. The intercellular CO₂ concentration, daily mean stomatal conductance, light saturation point, and apparent quantum yield in the three treatments of NH₄NO₃
 addition were all higher than those of the control, and the dark respiration rate was the highest in treatment high-N. The relative chlorophyll content was the highest in treatment medium-N, followed by in treatment highN, and had no significant difference between treatment lowN and the control. The chlorophyll fluorescence parameters varied with the levels of NH₄NO₃ addition. The PSⅡ primary chemical efficiency (F_v/F_m) and PSⅡ potential activity (F_v/F_o) were the lowest in treatment high-N, the superoxide dismutase activity was higher in nitrogen addition treatments than in the control, and the peroxidase activity, malonydialdehyde content, and membrane permeability were the highest in treatment high-N. All the results suggested that nitrogen deposition enhanced the photosynthetic ability of L. aggregata seedlings, with the most obvious effects in treatment medium-N, and altered the other physiological traits of the seedlings to different degrees.

Simulation model for the crop development stages in sunflower-potato intercropping.

GOU Fang, ZHANG Li-zhen, DONG Wan-lin, YU Yang, DI Wan-tong, SHEN Jiao-jiao

2012, 23(10):  2773-2778. 

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Potatosunflower intercropping is a prevailing cropping system in the agricultural and pastoral ecotone in China. To precisely simulate the crop phenology in the intercropping system is of significance for the assessment and optimization of intercropping systems. In this paper, the simulation model for the development stages of sunflower and potato in monoculture and intercropping was established, based on the crop’s physiological development time, and validated with the field experimental data from 2010 to 2011. A good fitness was observed between the simulated and observed values of the crop’s development stages. The root mean square error (RMSE) of the development stages from sowing to emergence, emergence to flowering, flowering to mature, and from sowing to mature was 1.2, 2.9, 2.4 and 2.6 d, respectively, with the prediction error lower than 5%. The model was strong on mechanistic, explanation and adaptability, and could be applied as a good tool in the researches of crop growth and development.

Seedling index of Salvia miltiorrhiza and its simulation model.

HUANG Shu-hua1, XU Fu-li2, WANG Wei-ling1, DU Jun-bo1, RU Mei1, WANG Jing1, CAO Xian-yan1

2012, 23(10):  2779-2785. 

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Through the correlation analysis on the quantitative traits and their ratios of Salvia miltiorrhiza seedlings  and  seedling quality, a series of representative indices reflecting the seedling quality of the plant species were determined, and the seedling index suitable to the S. miltiorrhiza seedlings was ascertained by correlation  degree analysis. Meanwhile, based on the relationships between the seedling index and the air temperature, solar radiation and air humidity, a simulation model for the seedling index of S. miltiorrhiza was established. The experimental data of different test plots and planting dates were used to validate the model. The results showed that the root diameter, stem diameter, crown dry mass, root dry mass, and plant dry mass had significant positive relationships with the other traits, and could be used as the indicators of the seedling’s health. The seedling index of S. miltiorrhiza could be calculated by (stem diameter/root diameter + root dry mass/crown dry mass) × plant dry mass. The stem diameter, root dry mass, crown dry mass and plant dry mass had higher correlations  with the seedling index, and thus, the seedling index determined by these indicators could better reflect the seedling’s quality. The coefficient of determination (R²) between the predicted and measured values based on 1:1 line was 0.95, and the root mean squared error (RMSE) was 0.15, indicating that the model established in this study could precisely reflect the quantitative relationships between the seedling index of S. miltiorrhiza and the environmental factors.

Thermal resources and maize temperature suitability in Northeast China under climate change.

YE Ming-zhu1,2, GUO Jian-ping2, YUAN Bin2, ZHAO Jun-fang2

2012, 23(10):  2786-2794. 

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This paper analyzed the spatiotemporal patterns of thermal resources and of temperature suitability of maize at its different growth stages in Northeast China, based on the 1951-2100 daily mean and minimum air temperature from RegCM3. In 1951-2100, the thermal resources in Northeast China had an obvious persistent increase, the first day of temperature ≥10 ℃ continued to be advanced, and the north boundary line in the zone of the first date of temperature ≥10 ℃ before April 25th moved eastward and northward. In 2071-2100, the first date in some areas of Liaoning Province would advance to March 26th, and the areas with active accumulated temperature ≥10 ℃ more than 3000 ℃·d, the length of growth season, and the areas suitable for late-maturing maize planting in Northeast China would increase persistently. In the region, the mean annual temperature in 2011-2100 would be 3.34 ℃ higher than that in 1981-2010. In 1951-2100, there was and would be an increasing temperature suitability of maize at its sowingheading stage. In 1951-2040, the maize temperature suitability at heading-maturing stage and in whole growth season was and would be higher in Liaoning Province than in Heilongjiang Province; in 2041-2100, the maize temperature suitability at heading-maturing stage and in whole growth season would decrease gradually in Liaoning Province but increase gradually in east Jilin Province and Heilongjiang Province.

Sowing date of corn in semiarid region of Jilin Province, Northeast China in adapting to climate change.

JIN Ying-hua1, ZHOU Dao-wei2, QIN Li-jie1

2012, 23(10):  2795-2802. 

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Under the background of global climate change, the climate in semiarid region of west Jilin Province changed greatly, producing a profound impact on the corn production in this region. In this study, the corn seeds were under three treatments (accelerating germination at 10 and 25 ℃, and dry seeds), and a field experiment with early sowing and traditional sowing was conducted in 2008 to investigate the effects of early sowing these seeds on the seedling emergence, growth, and yield, and compare the effects of early sowing and traditional sowing dates on the corn production and yield. In 1961-2010, the first day of the growth season of corn in semiarid region of west Jilin Province was advanced, the air temperature increased significantly, and the precipitation displayed a decreasing trend. At present, the corn sowing date in this region could be advanced to 11 th, April. Accelerating germination at 10 ℃, directly sowing dry seeds, and
  bedirrigation sowing all benefited the seedling emergence and cold resistance of early-sown seeds, and the corn plant height and leaf area under early sowing were significantly higher, with the yield increased by 35%-48%, compared with those under traditional sowing.  

Risk assessment and regionalization of maize drought disasters in Sichuan Basin, Southeast China.

WANG Ming-tian1,2, ZHANG Yu-fang2, MA Jun1, LIU Juan3, LI Jin-jian2, CHEN Dong-dong2

2012, 23(10):  2803-2811. 

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Based on the information of maize yield, phonological period, and related weather data, four models (those of climatic drought risk, crop drought risk, yield loss risk, and drought resistant capability) applicable for the assessment of maize drought risk in Sichuan Basin and the corresponding index systems were established, and a comprehensive model for assessing the maize drought disasters in the Basin was constructed, with the comprehensive index for the risk regionalization of the maize drought disasters determined. The values of the indices for assessing the maize drought risk in the Basin differed obviously with different regions, but showed similarity in some areas. The Sichuan Basin was divided into three regions, with high, medium and low maize drought risk, respectively. The region with high risk was mainly in the most areas of northwest basin, the middle basin, and parts of the south basin of Sichuan, the region with medium risk was in the north basin and some parts of the south basin, and the region with low risk was in the northeast and southwest basin, and parts of the southeast basin.

Correlative analysis of the diversity patterns of regional surface water, NDVI and thermal environment.

DUAN Jin-long1,2, ZHANG Xue-lei1,2

2012, 23(10):  2812-2820. 

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Taking Zhengzhou City, the capital of Henan Province in Central China, as the study area, and by using the theories and methodologies of diversity, a discreteness evaluation on the regional surface water, normalized difference vegetation index (NDVI), and land surface temperature (LST) distribution was conducted in a 2 km×2 km grid scale. Both the NDVI and the LST were divided into 4 levels, their spatial distribution diversity indices were calculated, and their connections were explored. The results showed that it was of operability and practical significance to use the theories and methodologies of diversity in the discreteness evaluation of the spatial distribution of regional thermal environment. There was a higher overlap of location between the distributions of surface water and the lowest temperature region, and the high vegetation coverage was often accompanied by low land surface temperature. In 1988-2009, the discreteness of the surface water distribution in the City had an obvious decreasing trend. The discreteness of the surface water distribution had a close correlation with the discreteness of the temperature region distribution, while the discreteness of the NDVI classification distribution had a more complicated correlation with the discreteness of the temperature region distribution. Therefore, more environmental factors were needed to be included for a better evaluation.

Variation trends of the vegetations in distribution region of Amur tiger based on MODIS NDVI.

WANG Hua-ru, WANG Tian-ming, GE Jian-ping

2012, 23(10):  2821-2828. 

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By using the averaged 250 m MODIS NDVI data in growth seasons of 2000-2010 and the approach of ordinary linear regression, this paper analyzed the variation trends of the vegetations in the distribution region of Amur tiger (Panthera tigris altaica), the Far East region of Russia and the eastern part of Northeast China, as well as the relationships between these variation trends and the anthropogenic activities. In 2000-2010, the areas with significantly decreased NDVI were sparsely distributed and accounted for 96% of the total, while the areas with significantly increased NDVI were mainly concentrated in the central part of northern Russia Far East Region and only accounted for 0.5% of the total. The percentage of the areas with significantly decreased NDVI in the distribution region of Amur tiger was slightly higher than that in the whole study region. The areas with significantly decreased NDVI were mainly distributed in the places of low elevation, gentle slope, and close to roads/railroads. The number of the pixels with significantly decreased NDVI increased with the increase of the nearest distance to residential locations first, and then decreased gradually. The significant decrease of the NDVI was closely related to the anthropogenic activities, and thus, to adopt effective measures to reduce human disturbances could control the vegetation degradation, and further, provide sustainable basis for the protection of Amur tiger and the conservation of the biodiversity in the studied region.

Driving forces of carbon emission from energy consumption in China old industrial cities: A case study of Shenyang City, Northeast China.

REN Wan-xia, GENG Yong, XUE Bing

2012, 23(10):  2829-2835. 

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To quantitatively analyze the effects of anthropogenic factors on regional environmental quality is a hot topic in the field of sustainable development research. Taking the typical old industrial city Shenyang in Northeast China as a case, and by using the IPCC method for calculating carbon emission from energy consumption, this paper estimated the carbon emission from energy consumption in the city in 1978-2009, and a time series analysis on the anthropogenic factors driving this carbon emission was made by the STIRPAT model based upon Kaya equation and ridge regression. In 1978-2009, the carbon emission in the city had a slow increase first, slow decrease then, and a rapid increase thereafter. The total carbon emission in 2009 was 4.6 times of  that in 1978. Population growth was the main factor driving the growth of the emission, and there existed an equalproportional variation between the population growth and the carbon emission growth. Urbanization was another main driving factor followed by population growth, and the per capita GDP was positively correlated with the carbon emission. Kuznets curve did not exist for the relationship between economic development and carbon emission in Shenyang. Energy source intensity reduction (representing technology improvement) was the main factor driving the reduction of the total carbon emission.

Analysis on barriers  of urban sustainable development based on DEMATEL: A case of Shenyang City.

LI Chun-rong1,2, GENG Yong1, XUE Bing1, REN Wan-xia1, DONG Hui-juan1,2

2012, 23(10):  2836-2842. 

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To scientifically identify the key barriers which the urban sustainable development is facing and to analyze the interrelationships among the barriers are of significance to promote urban sustainable development. Through literature review, site investigation and structural interview,  21 factors affecting the Shenyang City’s sustainable development were recognized, and based on questionnaire survey and statistics analysis, 12 main factors were screened. Further, by employing decision-making and trial evaluation  laboratory  (DEMATEL) method, the interrelationships among these factors were analyzed. The key factors affecting the Shenyang’s sustainable development included the lack of leaders’ attention, the economyoriented governmental performance evaluation system, the lower public awareness on sustainable development, and the lack of academic understanding on regional eco-carrying capacity and related key projects. It was suggested that the local government should pay more attention on sustainable development, increase propaganda activities, reform governmental performance evaluation system, establish a reward-punishment system for promoting sustainable development and an effective monitoring mechanism, and enhance the implementation of related regulations, the local enterprises should establish research and development funds to support the researches of key technologies and introduce key projects, and general publics should improve their awareness on sustainable development and actively participate in related activities.  

Ecological effects of wheat-oilseed rape intercropping combined with methyl salicylate release on Sitobion avenae and its main natural enemies.

DONG Jie1, LIU Ying-jie1, LI Pei-ling1, LIN Fang-jing1, CHEN Ju-lian2, LIU Yong1

2012, 23(10):  2843-2848. 

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In order to explore the effects of wheat-oilseed rape intercropping in combining with methyl salicylate (MeSA) release on Sitobion avenae and its main natural enemies, a field experiment was conducted at the Tai’an Experimental Station of Shandong Agricultural University in East China from October 2008 to June 2010 to study the temporal dynamics of S. avenae and its main natural enemies as well as the ecological control effect on the aphid. In the plots of intercropping combined with MeSA release, the S. avenae apterae population reached a peak about 12 d in advance of the control, but the peak value was significantly lower than that of the control. The average annual number of S. avenae apterae per 100 wheat tillers decreased in the order of wheat monoculture > wheatoilseed rape intercropping > MeSA release > wheat-oilseed rape intercropping combined with MeSA release. Moreover, the total number of ladybeetles was the highest in the plots of intercropping combined with MeSA release. The population densities of aphid parasitoids reached a peak about 10 d in advance of the control, which could play a significant role in controlling S. avenae at the filling stage of wheat. Taking the biological control index (BCI) as a quantitative indicator, and with the ladybeetles and parasitoids as the dominant control factors in fields, it was observed that wheatoilseed rape intercropping combined with MeSA release could suppress the population increase of S. avenae apterae effectively from the heading to filling stages of wheat.

Effects of different years of planting Pennisetum sp. on the plant and insect diversity in Pennisetum sp. communities.

LIN Xing-sheng1, LIN Zhan-xi1, LIN Dong-mei1, LIN Hui1, LUO Hai-ling1, HU Ying-ping1, LIN Chun-mei1, ZHU Chao-zhi2

2012, 23(10):  2849-2854. 

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This paper studied the effects of 1-, 2- and 3 years of planting Pennisetum sp. on the plant and insect diversity in the Pennisetum sp. communities, taking the barren mountain land without planting Pennisetum sp. as the control (CK). Compared with CK, the plant species richness in Pennisetum sp. communities with different years of planting was lower, but the coverage was higher. The coverage in the Pennisetum sp. community having been planted for 3 years was the highest, up to 91.6%, and 75.8% higher than the CK. The insect species richness in the Pennisetum sp. communities having been planted for 1, 2 and 3 years was 3.6, 5.3 and 5.6 times of  the CK, respectively. The plant and insect diversity indices, including Simpson index, Shannon index, evenness, Brillouin index, and McIntosh index for the Pennisetum sp. communities with different years of planting were significantly higher than the CK, which indicated that the growth of Pennisetum sp. could affect the plant and insect diversity. With the increasing year of planting, the plant and insect diversity in Pennisetum sp. communities tended to be stable.

Combined toxicity of copper and cadmium to cladoceran Moina marocopa.

SHEN Peng, XI Yi-long, ZHANG Ye, ZHOU Bin, WANG Min

2012, 23(10):  2855-2862. 

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In this paper, the 48 h LC₅₀ values of Cu²⁺， Cd²⁺ and Cu²⁺+Cd²⁺(Cu²⁺-Cd²⁺=1:1) to Moina macrocopa were determined by acute toxicity tests, and the effects of different concentrations of Cu²⁺, Cd²⁺ and Cu²⁺+Cd²⁺ on the life table demography of M. macrocopa were studied by life table demography. The 48 h LC₅₀ of Cu²⁺, Cd²⁺ and Cu²⁺+Cd²⁺ to M. macrocopa was 0.106, 0.117 and 0.212 mg·L^-1, respectively, and the acute toxicity of Cu²⁺+Cd²⁺ mixture to M. macrocopa showed an antagonistic effect. Cu²⁺ had no significant effects on the life expectancy at hatching, gross reproductive rate, net reproductive rate, generation time, and intrinsic rate of population increase of M. macrocopa, whereas Cd²⁺ and Cu²⁺+Cd²⁺ had significant effects on the life expectancy at hatching, gross reproductive rate, net reproductive rate and generation time, but no significant effects on the intrinsic rate of population increase of M. macrocopa. Compared with the control, the 0.004 and 0.005 mg·L^-1 of Cd²⁺ and the 0.006-0.010 mg·L^-1 of Cu²⁺+Cd²⁺ decreased the life expectancy at hatching and the gross reproductive rate of M. macrocopa significantly, and the 0.004 and 0.005 mg·L^-1 of Cd²⁺ and the 0.008-0.010 mg·L^-1 of Cu²⁺+Cd²⁺ reduced the net reproductive rate and the generation time of M. macrocopa significantly. The chronic toxicity of Cu²⁺+Cd²⁺ mixture to M. macrocopa showed a synergistic effect. There existed significant doseeffect relationships between the concentrations of Cd²⁺ and Cu²⁺+Cd²⁺ and the life expectancy at hatching, gross reproductive rate, net reproductive rate, and generation time of M. macrocopa.

Annual dynamics of cladocera community structure in Backshore Wetland of Expo Garden, Shanghai.

CHEN Li-jing1, WU Yan-fang1, JING Yu-xiang1, WANG Cong2, ZHANG Yin-jiang2

2012, 23(10):  2863-2870. 

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The Backshore Wetland of Expo Garden, Shanghai was one of the key parts of the World Expo construction project in 2010. From September 2009 to August 2010, a monthly investigation was conducted to understand the spatiotemporal dynamics of cladocera community structure (including species composition and standing crop) and related main affecting factors in the Backshore Wetland. A total of 36 cladocera species in 13 genera of 5 families were identified through the year. There were 12 dominant species, mainly Chydorus sphaericus,C. ovalis, Diaphanosoma leuchtenbergianum, and Sida crystalline. The mean annual abundance and biomass of the cladocera were 5.7 ind·L^-1 and 0.3559 mg·L^-1, respectively, and the annual dynamics of the standing crop showed bimodal, with the main peak in April and July, and the second peak in July and May, respectively. The Shannon index, Pielou index, and Margelf index were high in summer and autumn, but low in winter and spring. The canonical correspondence analysis (CCA) showed that water temperature, pH, dissolved oxygen, and nitrite nitrogen were the main factors affecting the community structure of cladocera in the Backshore Wetland.

Land layout for lake tourism based on ecological restraint.

WANG Jian-ying1, LI Jiang-feng1,2, ZOU Li-lin2, LIU Shi-bin2

2012, 23(10):  2871-2877. 

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To avoid the decrease and deterioration of lake wetlands and the other ecological issues such as lake water pollution that were caused by the unreasonable exploration of lake tourism, a land layout for the tourism development of Liangzi Lake with the priority of ecological security pattern was proposed, based on the minimal cumulative resistance model and by using GIS technology. The study area was divided into four ecological function zones, i.e., core protection zone, ecological buffer zone, ecotone zone, and human activity zone. The core protection zone was the landscape region of ecological source. In the protection zone, new tourism land was forbidden to be increased, and some of the existing fundamental tourism facilities should be removed while some of them should be upgraded. The ecological buffer zone was the landscape region with resistance value ranged from 0 to 4562. In the buffer zone, expansion of tourism land should be forbidden, the existing tourism land should be downsized, and human activities should be isolated from ecological source by converting the human environment to the natural environment as far as possible. The ecotone zone was the landscape region with resistance value ranged from 4562 to 30797. In this zone, the existing tourism land was distributed in patches, tourism land could be expanded properly, and the lake forestry ecological tourism should be developed widely. The human activity zone was the landscape region with resistance value ranged from 30797 to 97334, which would be the key area for the land layout of lake tourism. It was suggested that the land layout for tourism with the priority of landscape ecological security pattern would be the best choice for the lake sustainable development.

Structure and function of Lidao artificial reef ecosystem in Rongcheng of Shandong Province, East China: An evaluation based on Ecopath model.

WU Zhong-xin1, ZHANG Xiu-mei1, ZHANG Lei1, TONG Fei1, LIU Hong-jun2

2012, 23(10):  2878-2886. 

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Based on the annual investigation data of biological resources in Lidao artificial reef zone in 2009, an Ecopath model of the Lidao artificial reef ecosystem was constructed to analyze the energy flow pattern and the system attributes of the ecosystem. The model was consisted of 19 functional groups, basically covering the main processes of the energy flow in the Lidao artificial reef ecosystem. The functional groups were divided according to the relationships of the corresponding positions between appeared fishes and artificial reefs, and the planktonic heterotrophic bacteria were included into the model as a functional group. The fishes appeared in the investigation zone were divided into seven functional groups, and the trophic levels of the functional groups varied from 1.00 to 3.72. The typeⅠfishes had the highest trophic level. The total system throughput was estimated to be 10786.68 t·km^-2·a^-1, 27% of which flowed to detritus, and 17% flowed out the ecosystem in the forms of fishing and sediment. The total net primary productivity of the system was 4131.97 t·km^-2·a^-1, and the total energy transfer efficiency was 10.5%. The proportion of the total flow originated from detritus was 39%, and that from primary producers was 61%, indicating that the energy flow was dominated by food web rather than detritus. The ratio of total primary productivity to total respiration of the system was 1.84, the connectivity index was 0.20, and the Finn’s cycling index and the mean path length of the energy flow were 4.5% and 2.62, respectively. This study showed that the Lidao artificial reef ecosystem had a relatively low maturity and stability, was at a developing stage, and had weak resistance against outside interference. The ecological environment and the output of fisheries in the artificial reef zone would have inter-annual fluctuations, and thus, the ecoenvironment restoration of the artificial reef ecosystem could only be realized by the sustainable maintaining of the ecosystem.

Effects of environmental factors on catch distribution of stow net Pseudosciaena polyactis and Lophius litulon in southern Yellow Sea in spring.

LI Zeng-guang, YE Zhen-jiang, ZHANG Chi, ZHUANG Long-chuan

2012, 23(10):  2887-2892. 

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Stow net fishery is one of the important fishing methods in southern Yellow Sea. Based on the 2006-2009 data from the stow net fishery resources survey in the southern Yellow Sea in spring, and by using the generalized linear model (GLM) and generalized additive model (GAM), this paper quantitatively analyzed the relationships between the catch distribution of Pseudosciaena polyactis and Lophius litulon and the environmental factors such as year, position, water depth, and sea surface temperature (SST). Compared with GLM model, GAM model could better explain the relationships between the spatiotemporal distribution of the catch per unit effort (CPUE) of P. polyactis and P. litulon and the environmental factors. There was a significant negative correlation between the CPUE of the two fish species. The P. polyactis’ CPUE showed a decreasing trend from north to south along the latitude direction, being smaller especially around the Yangtze River estuary, and the L. litulon’s CPUE was also smaller near the Yangtze River estuary. The CPUE of the two species showed a  significant correlation with the SST. The calculated optimal scale of the SST for L. polyactis and P. litulon was 9-11 ℃ and 9-14 ℃, respectively.

Effects of water temperature, salinity and pH on sex differentiation of Oreochromis niloticus.

WANG Hai-zhen1, WANG Hui1, QIANG Jun2, XU Pao2, LI Rui-wei3

2012, 23(10):  2893-2899. 

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By using Box-Behnken design and response surface methodology, this paper studied the effects of three major environmental factors, i.e., water temperature (20-36 ℃), salinity (0-16), and pH (5.5-8.5), on the sex differentiation of GIFT strain Nile tilapia (Oreochromis niloticus). It was observed that water temperature had highly significant linear and quadratic effects on the sex differentiation, water salinity and pH had non-significant linear and quadratic effects, and the twofactor interactions of the three factors were not significant. The analysis with response surface methodology showed that the male rate of the GIFT tilapia increased with increasing water temperature, and at water temperature 36 ℃, salinity 8, and pH 8.5, the male rate reached the maximum (80%). A model equation about the relationships of the male rate with the three major environmental factors was established， and after eliminating the related non-significant factors, an optimal model equation about the relationship between the male rate and water temperature was attained, which could predict the variation of the GIFT tilapia male rate.

Selenium cycling and transformation in paddy field and selenium nutrition of rice: A review.

ZHANG Jun-hua, ZHU Lian-feng, YU Sheng-miao, JIN Qian-yu

2012, 23(10):  2900-2906. 

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Due to the alternate variation of soil redox potential and the particularity of soil components in paddy field, the selenium (Se) cycling and transformation in paddy soil are obviously different from those in upland soil, and can affect the Se availability in soil and the Se absorption and accumulation by rice. To deeply understand the Se cycling and transformation in paddy soil and the Se absorption and accumulation by rice is of great importance in studying the transformation of soil inorganic Se to organic Se. This paper summarized the researches on the cycling mechanisms and form transformation of Se in paddy soil and the metabolic mechanisms and absorption characteristics of Se by rice, and discussed the present status and development trend of the studies on the Se-transformation in soil-rice system and the Se translocation in rice plant, which could provide references for the study of soil Se availability and the cultivation of Se-enriched rice.

Staged strategy of plants in response  to drought stress.

AN Yu-yan, LIANG Zong-suo

2012, 23(10):  2907-2915. 

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Drought is one of the most important abiotic factors limiting plant growth, development and survival. Due to global warming, the drought episodes in the future will become more frequent and severe. Therefore, the plant responses to drought stress, especially the droughtresistant mechanisms, have been a focus of the studies. This paper summarized the plant growth and physiological responses to drought stress, and proposed a staged response strategy of plants for the adaptation to natural drought stress. Overall, from drought initiation to droughtinduced death, plants experienced five stress stages with increasing drought intensity, i.e., drought initiation-mild drought-moderate drought-severe drought-extreme drought, and the plant responsive and adaptive process in this whole event could be acute response-active adaptation to mild and severe drought stresses-passive adaptation to extreme drought stress. The essential function of the plant droughtresistant mechanisms varied with drought stress stages. Some key scientific problems and research directions about the staged response characteristics of plants to drought stress needed to be solved urgently in the future were pointed out.

Dynamic observation, simulation and application of soil CO₂ concentration: A review.

SHENG Hao1, LUO Sha1, ZHOU Ping2, LI Teng-yi1, WANG Juan1, LI Jie1

2012, 23(10):  2916-2922. 

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Soil CO₂ concentration is the consequences of biological activities in above and belowground, and its fluctuation may significantly affect the future atmospheric CO₂ concentration and the projected climate change. This paper reviewed the methodologies for measuring the soil CO₂ concentration in situ as well as their advantages and disadvantages, analyzed the variation patterns and controlling factors of soil CO₂ concentration across the temporal (diurnal, several days, seasonal and interannual) and spatial (soil profile, site and landscape) scales, introduced the primary empirical and mechanical models for estimating and predicting soil CO₂ concentration, and summarized the applications and constraints of soil CO₂ concentration gradient in determining soil respiration. Four research priorities were proposed, i.e., to develop new techniques for collecting and determining the soil CO₂ in severe soil conditions (e.g.,flooding, lithoso and others), to approach the responses of soil CO₂ concentration to weather change and related regulation mechanisms, to strengthen the researches on the spatial heterogeneity of soil CO₂ concentration, and to expand the applications of soil CO₂ concentration gradient in the measurement of tropicalsubtropical soil respiration.

Applications of soil metaproteomics in soil pollution assessment: A review.

ZHANG Xi1,2, LI Feng1,2, LIU Ting-ting1,2, CHEN Ying-xu2

2012, 23(10):  2923-2930. 

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Soil microbial indicator is one of the important biological indicators in evaluating the extent of soil contamination. In recent years, with the development of molecular biology, many studies have focused on the ecological functions of soil microorganisms by using metagenomics, metatranscriptome and metaproteomics.  Relative to metagenomics and metatranscriptome, soil metaproteomics aims to investigate the spatial and temporal changes of the proteins extracted from soil as well as the functional components of soil microbial genomic expression products, which is more conclusive to explore the ecological functions of soil microbes and their roles in soil pollutants transportation and transformation. Therefore, soil metaproteomics has great potential in soil pollution assessment. Currently, soil metaproteomics is still at its infancy stage, while soil protein extraction method is one of the key factors restraining the potential application of soil metaproteomics. In this paper, the advantages and disadvantage of soil metaproteomics in soil pollution assessment were reviewed, with the focus on the comparison of different soil protein extraction methods. In combining with case studies, the feasibility and limits of soil proteins as an indicator for soil pollution assessment were analyzed. In addition, the future research perspectives on the development of soil metaproteomics were discussed.