Table of Content

10 September 2014, Volume 33 Issue 9

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Partitioning of organic carbon in Leymus chinensis grossland ecosystems with different population densities in Songnen grassland, China.

ZHANG Hai-yan1,2, SHEN Xiang-jin1,2, LI Fei1,2, GUAN Sheng-chao1,2, ZHOU Dao-wei1**

2014, 33(9):  2281-2287. 

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In this study, we investigated the biomass distribution, organic carbon concentration and stock of each plant component, and soil organic carbon concentration and stock of Leymus chinensis grossland  ecosystems with different population densities in Songnen grassland by combing field sampling with laboratory analysis. Results showed that the biomass of L. chinensis reproductive components decreased obviously with the increase of population density; however, there were no significant differences in the biomass of root, stems, leaves, rhizome and shoot ratio among L. chinensis communities of different population densities. Population density had no significant effects on the organic carbon concentration of L. chinensis components. With the increase of population density, the organic carbon stock of L. chinensis reproductive components reduced significantly (P<0.05), while the population density had no significant effects on nonreproductive components. Population density influenced the capacity of soil carbon sequestration. The low population density of L. chinensis  grossland  ecosystems had a higher carbon sequestration capacity than the high population density ecosystems, especially for the 20-100 cm soil depth (P<0.05).

Impacts of ecological restoration on vegetation carbon storage in the typical karst region of northwest Guangxi, China.

ZHANG Ming-yang1,3, WANG Ke-lin1,3**, LIU Hui-yu2, WANG Jing1,3, YUE Yue-min1,3

2014, 33(9):  2288-2295. 

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It is important to investigate the vegetation carbon storage for assessing the ecological services of ecological restoration measures in karst areas of southwest China, where the Grain for Green Program and ecological emigration have been deployed since 1999. The temporalspatial dynamics of vegetation carbon storage in the typical karst region of northwest Guangxi during 2000-2010 were analyzed based on MODIS remote sensing data and weather data in couple of the technique of geographic information system. Vegetation net primary productivity (NPP) and net ecosystem production (NEP) tended to increase with fluctuation during 2000-2010, with annual NPP and NEP of 396.61 g C·m^-2 and 370.58 g C·m^-2, respectively, and the percentages of area with significant changes (P<0.05) for NPP and NEP were 21.14% and 18.09%, respectively. With regard to spatial distribution, greater values were recorded in the western nonkarst areas (NPP: 422.73 g C·m^-2; NEP: 397.25 g C·m^-2), while the largest increments of NPP and NEP were recorded in the eastern part of restoration area of karst rocky desertification (NPP 34.20 g C·m^-2, NEP 30.30 g C·m^-2) (P<0.05). No significant correlation was found between annual NPP, NEP and precipitation or temperature. This study suggests that the vegetation carbon storage has been significantly increased by ecological restoration measures, such as ecological emigration, Grain for Green Program and accordingly the ecological services have been improved in this region.

Effects of lightfelling on carbon budget of mid-term Korean pine forests by planting conifer and reserving broad-leaved tree in Changbai Mountains of China.

HAN Yang-rui1,2, MU Chang-cheng1**, ZHUANG Chen1, ZHANG Xiao-liang1, TONG Jing-qiu1, CHENG Jia-you3, CAO Wan-liang4

2014, 33(9):  2296-2307. 

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By using lightfelling experiment and measuring carbon fluxes, the effects of lightfelling on the carbon budget of a midterm Korean pine forests restored by planting conifer and reserving broadleaved trees were investigated in Changbai Mountains of China. The results showed that both highintensity lightfelling and clearcutting significantly decreased CO₂ effluxes of soil respiration, autotrophic respiration, and heterotrophic respiration by 34.1%-39.2%, 37.2%-42.4% and 31.5%-37.3% (P<0.05), respectively in the growing season, while the low and moderateintensity lightfelling had no significant effects. Low and moderateintensity lightfelling and clearcutting had no significant effects on the net primary productivity and net carbon sequestration from the Korean pine forest (P>0.05), however, highintensity lightfelling significantly decreased the net primary productivity and net carbon sequestration by 24.7% and 27.0%, respectively (P<0.05). Compared to the uncut stands, highintensity lightfelling and clearcutting significantly decreased carbon emissions by 41.5% and 84.1%, respectively (P<0.05), while low and moderateintensity lightfelling had no influences on carbon emissions. Therefore, the highintensity lightfelling and clearcutting should be taken for the midterm Korean pine forests restored by planting conifer and reserving broadleaved trees, in order to maintain forest carbon sinks and accelerate their recovery to climax forests.

Estimation of aboveground carbon density for tree forests based on remote sensing data in Yangquan of Shanxi Province, China.

LI Jiao1, ZHANG Hong1**, ZHANG Li-qiu1, HAN Jian-ping2

2014, 33(9):  2308-2315. 

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In order to investigate the feasibility of using remote sensing data to determinate the aboveground carbon density for tree forests, we estimated the biomass and carbon density of forests in Yangquan region of Shanxi Province by using the variable BEF (biomass expansion factor) method based on the forest inventory data. We then selected the NDVI, RVI, bands of SPOT images and environmental factors (elevation, slope, aspect etc.) as independent variables, and established an estimation model by using the enhanced BP neural network method to derive a distribution map of the carbon density. The biomass of tree forests in Yangquan was 552774 t, and the carbon density was 11.38 t·hm^-2. Needleleaved forest, young forest and artificial forest had the largest biomass, while broadleaved forest, mature forest and natural forest had the largest carbon density. Model predictions of carbon density were successful, with the average relative errors and the average absolute values of relative error of simulation results for needleleaved forest, broadleaved forest, and mixed forest being 2.40%, 6.87%, -4.09%, and 6.83%, 2.77%, 3.99%, respectively. The simulation accuracy of tree forest distribution map derived by the enhanced BP neural network model was 85.05%, implying that artificial neural networks developed a new idea for fast and accurate estimation of forest carbon density, providing a scientific basis for future survey and management of forest resources.

 

Life history characteristics and point pattern of Betula platyphylla population in Qiliyu region, Shanxi, China.

JIN Jing-jing, ZHANG Qin-di, BI Run-cheng**

2014, 33(9):  2316-2321. 

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In order to understand the life history characteristics and the pattern of the spatial distribution of Betula platyphylla population in the Qiliyu region of Shanxi Province, the life table characteristics, age structure, survival curve and spatial distribution of the B. platyphylla population were studied. The results showed that, 1) the age structure of the B. platyphylla population of the Qiliyu region followed a spindle shape, which indicated that the population was declining; 2) the survivorship curve of B. platyphylla population approximated the type of the Deevey I; 3) selfthinning was common in this population, because of the high interspecific competition for space and sunlight, which led to a higher death rate in age class III; 4) the spatial distribution in different growth periods was clumped or random. To be specific, the distribution pattern tended to be clumped when interspecific competition was not intense, and the clumping distribution became more significant with age increase. Based on our findings, we concluded the spatial patterns of the B. platyphylla population in this area of uniform environment conditions were controlled by biotic interactions and local ecological characteristics.

Morphological plasticity of fine root traits in Larix plantations across a latitude gradient.

NI Wei1,2, HUO Chang-fu1, WANG Peng1**

2014, 33(9):  2322-2329. 

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We elucidated the changes in larch fine root (diameter <2 mm) traits and environmental factors in 5 sites across a latitudinal gradient in China, linking the fine root morphological traits (e.g. mean root length, mean root diameter, specific root surface area (SRA) and specific root length (SRL) with climate and soil factors. Along with the increase in latitude, the mycorrhizal fungal infection rates of the first and second order roots decreased clearly, the numbers of ectomycorrhizas forks increased and color became darker, and the mean root diameter and root length got smaller, while the SRL and SRA got larger. Furthermore, there was a significant positive correlation between root diameter, length and mean annual precipitation (MAP), mean annual temperature (MAT) and soil water content. Also, a strong positive correlation was observed between SRL, SRA and soil TC, soil nutrients. The results of our study demonstrated that both ECM and noninfested fine root had clear morphological plasticity across a latitude gradient, and ECM morphological traits varied with sitespecific characteristics, and root diameter and root length were mainly affected by climatic factors, whereas SRA and SRL were mainly modified by soil factors.

Effects of light and cold storage on seed germination of three shrub species from the eastern QinghaiTibet Plateau.

CUI Xian-liang, LUO Ya-ting, JIANG Zhi-lin, SU Zhi-long, Li Sun-yang, LUO Yin-ling**

2014, 33(9):  2330-2335. 

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The fresh mature seeds of three shrubs (Philadelphus incanus, Spiraea alpine and S. rosthornii) were collected from the eastern QinghaiTibet Plateau. After the seeds were stored at 5 ℃ for different time (0, 40, 80 and 160 d), they were used for germination under 5 ℃/25 ℃ and 12 h/12 h photoperiod in a growth incubator. In addition, the seeds naturally dehydrated at room temperature for 120 d were used for germination at 10 ℃/25 ℃ under five light conditions (white light, dark, red light, blue light, 12 h/12 h light/dark). Cold storage time had significant effects on the germination of the seeds of the three shrub species. Cold storage improved the germination ability of P. incanus and S. rosthornii, but reduced the germination ability of S. alpine. There were very significant differences in germination percentage among different light conditions for P. incanus seeds. The highest germination percentage and fastest germination rate were recorded under red light and 12 h/12 h light/dark, and the lowest germination percentage and slowest germination rate were found under dark and blue light. Seeds of S. rosthornii exhibited significant differences in germination percentage and germination rate among the different light conditions. The germination percentages under white light, red light, blue light, and 12 h/12 h light/dark were all more than 80%, and were significantly higher than that under dark. The germination rate was fastest under red light, and lowest under blue light. There were no significant differences in germination percentages among the different light conditions for S. alpine seeds. The germination percentages under all light conditions were more than 93%. But S. alpine seeds germinated fastest under red light and dark, while lowest under blue light. The results indicated that cold storage, as a dormancy breaking treatment, had different effects on seed germination for diversified species; however, as a trigger factor of germination, red light had consistent effects on seed germination among different species.

Diurnal variation of photosynthesis of different plants in summer in Yintan wetland of Lanzhou section of Yellow River.

KANG Ya-rong1, ZHANG Hua1,2**

2014, 33(9):  2336-2342. 

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In order to understand the photosynthetic characteristics of dominant species in Yintan wetland of Lanzhou section of Yellow River in summer, ten species were selected, including Lythrum salicaria, Phragmites communis, Polygonum lapathifolium, Echinochloa crusgalli, Solanum nigrum, Amaranthus retroflexus, Datura stramonium, Onobrychis viciaefolia, Scirpus triqueter, and Juncellus serotinus. Then, the diurnal variations of photosynthetically active radiation (PAR), net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular CO₂ concentration (C_i) of the mature leaves of each plant, and the atmospheric temperature (T_a) and atmospheric CO₂ concentration (C_a) were measured by employing the CI-340 portable photosynthetic system. The curves of diurnal variation of P_n in leaves of seven plants showed two peaks, suggesting a remarkable photosynthetic “midday depression”, which was caused by stomatal limitation and nonstomatal limitation. Correlation analysis and stepwise regression analysis showed that there was good correlation between P_n and T_r, G_s, PAR in most plants, and each factor had different coefficients of contribution to P_n, indicating that the main physiological and ecological factors influencing the photosynthetic rate were different among species. Moreover, strong light and high temperature at noon intensified the transpiration rate of wetland plants. Our study provides information on understanding the relationship between photosynthetic characteristics and environmental factors of the dominant species, and on species selection of planting wetland plants.

 

Effects of combined stress of elevated temperature and drought and of rewatering on the photosynthetic characteristics and chlorophyll fluorescence parameters of Broussonetia papyrifera seedlings.

YE Bo, WU Yong-bo**, SHAO Wei, YANG Jing

2014, 33(9):  2343-2349. 

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In recent years, with the global climate change, high temperature and temporal drought during summer seasons have increasingly taken place in some subtropical regions. Consequently, the survival and growth of plants are restrained under the combined stress of high temperature and drought. In the present study, at different controlled temperature and soil moisture levels, the combined stress of high temperature and drought on the photosynthetic characteristics and chlorophyll fluorescence parameters of Broussonetia papyrifera seedlings, as well as the alleviation role of rewatering, were measured. The results showed that, under the combined stresses, the net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), maximal fluorescence (F_m), optimal/maximal photochemical efficiency of PSⅡ (F_v/F_m) of B. papyriferas seedlings presented a decreasing tendency, while minimal fluorescence (F₀) presented an increasing tendency. Combined stress showed synergistic effects on P_n, G_s, and T_r. The parameters such as intercellular CO₂ concentration (C_i), G_s, F_m and F_v/F_m showed significant differences among various temperature levels, and the parameters such as G_s, T_r, F₀ showed significant variations among different soil moisture levels, while P_n and F₀ were influenced by both temperature and soil moistures levels. Rewatering alleviated the stress at 25 and 33 ℃ through improving the photosynthesis performance and F_v/F_m to some degree, but no obvious variation in terms of F₀ and F_m after rewatering. Our results suggest that the combined stress has stronger effects on the photosynthetic characteristics of plants than the single stress, and rewatering can release the stress in a certain temperature range.

Effects of different O₃ concentrations on leaf physiology of Phellodendron amurense Rupr. seedlings.

FU Wei1,2, DENG Li-lan1, XU Sheng2**, HE Xing-yuan2, CHEN Wei2, LI Mei2,3, ZHAO Yi2， SU Li-li2

2014, 33(9):  2350-2356. 

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Fouryearold Phellodendron amurense Rupr. seedlings were exposed to four levels (40 (CK), 80, 120, and 200 nmol·mol^-1) of O₃ in opentop champers (OTCs). The changes in photosynthetic pigment contents, net photosynthesis rate, lipid peroxidation and the activity of antioxidative enzymes were periodically measured in leaves of P. amurense. The results showed that with the increasing O₃ concentration and exposure time, total chlorophyll (Chl) contents, carotenoid (Car) contents and net photosynthesis rate (P_n) were significantly decreased by 52.76%, 44.57% and 54.67%, respectively (P<0.05); electrolyte leakage and malondialdehyde (MDA) contents were significantly increased by 101.49% and 70.21%, respectively (P<0.05). When the O₃ concentration was 80 nmol·mol^-1, the maximum photochemical efficiency (F_v/F_m) had no significant change, while a significant decrease in F_v/F_m was observed when the O₃ concentration was increased to 120 or 200 nmol·mol^-1, showing a significant harm of photosynthetic system function by high O₃ concentrations. Superoxide dismutase (SOD) activity increased at the first fourteen days exposure and then decreased by 17.22%. Compared with CK, the superoxideanion (O₂^-_·) content increased significantly (P<0.05) when the O₃ concentration was 120 or 200 nmol·mol^-1, while only increased significantly in the seventh day  when the O₃ concentration was 80 nmol·mol^-1. It is concluded that P. amurense can tolerate moderately high concentrations of O₃ for a period which is related to its antioxidative ability. Higher O₃ concentrations or longer exposure would incur harm to the photosynthetic system of the leaves.

Effects of controlled urea fertilizer specialized for bamboo on aboveground biomass, nitrogen use efficiency of Moso bamboo.

FENG Huan-ying, FAN Shao-hui**, SU Wen-hui**, LIU Guang-lu

2014, 33(9):  2357-2362. 

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Controlled release fertilizers (CRF) have potential to increase fertilizer use efficiency of crop through regulating the nutrient release rate. According to the growth characteristics of bamboo, two controlled urea fertilizers for bamboo (CUF-1 and CUF-2) was developed with slag coated urea mixed with other nutrient elements. In this study, we assessed the aboveground biomass and nitrogen use efficiency of Ⅰ du bamboo (growing into normal bamboo in 2012), Ⅱ du bamboo (growing into normal bamboo in 2010), and Ⅲ du bamboo (growing into normal bamboo in 2008) treated with CUF-1, CUF-2, or common compound fertilizer (CCF), and a nonfertilization (CK) treatment was also included as the control. The results showed that the bamboo DBH, height, weigh of standard branch and leaf, and SPAD all significantly increased under CUF-1 and CUF-2 treatments compared with that of CK, but were not significantly different compared with CCF. The application of CUF-1 and CUF-2 improved the aboveground biomass and enhanced the accumulation of nitrogen of Ⅰ du and Ⅱ du, but such changes in Ⅲ du were negligible. The increases in biomass and nitrogen accumulation by applications of CUF-1 and CUF-2 were 19%-61% and 29%-99% for Ⅰ du bamboo, 36%-59% and 55%-89% for Ⅱ du bamboo, and less than 8% and 15% for Ⅲ du bamboo, respectively. The nitrogen use efficiencies of the treatments CUF-1 and CUF-2 were 69.02% and 56.82%, respectively, being higher than the treatment CCF (19.60%). Therefore, it is suggested that CUF could greatly improve the nitrogen use efficiency of bamboo forest land.


 

Morphological responses of three Sphagnum species to drought and interspecific interaction.

GE Jia-li1, BU Zhao-jun1**, ZHENG Xing-xing1,2, MA Jin-ze1, CUI Wei-lin1, GU Xiao-nan1

2014, 33(9):  2363-2368. 

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Sphagnum is a dominant genus in peatlands, and can differentiate into hummock species and hollow species, both of which often face the threat of drought. However, how they response to drought and interspecific interaction in morphological traits is rarely known. Under simulated wet and dry conditions, we established an experiment by setting different communities with Sphagna, two hummock species Sphagnum palustre and S. capillifolium and one hollow species S. fallax, to analyze the effects of drought and interspecific interaction on biomass production, height increment, sideshoot production and leaf hyaline cell volume percentage (HCP) of Sphagna. The results showed that drought caused decreases in biomass production, height increment and sideshoot production in all three species, and increased HCP of S. palustre and S. capillifolium. In addition, neighborhood significantly inhibited biomass production and sideshoot production of S. palustre, and reduced HCP of S. capillifolium. Interaction between drought and neighborhood was found in HCP in all the three species. Our study suggests that the three Sphagnum species can adapt to drought and interspecific interaction through morphological adjustment, and the capacity of droughttolerance of hummock species should attribute to the increase of waterholding ability by increasing HCP.

 

Correlation of soil nutrients and plant community in ecological reclamation of opencast coal mine in a semiarid area.

LIU Wei-hua1, ZHAO Bing-qing2, BAI Zhong-ke3,4, SHANGGUAN Tie-liang1,2, DUAN Yi-hao2, ZHANG Jie5, GUO Dong-gang2**

2014, 33(9):  2369-2375. 

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A 0.8hm² plot at the ecoreclamation area in Antaibao Opencast Coal mine of ChinaCoal Pingshuo Coal Company Limited was established for monitoring the plant community and soil after reforestation of a mixed plantation of locust (Robinia pseudoacacia) and pine (Pinus tabuliformis). The relationships among the factors of soil pH, nutrients, vegetation density, tree height and DBH were examined. The results showed that the organic matter, total N and available K were similar to or higher than those of the original landscape, while the pH, available N and P were far lower than those prior to mining activities. In the same profile, the soil nutrients at 0-20 cm depth were significantly higher than at 20-40 cm depth. For both tree species, the tree density was negatively correlated to the mean height and DBH and well fitted through simple linear regressions. The density, height and DBH of R. pseudoacacia population were significantly correlated with the soil pH, available N and P. The principal component analysis revealed that the contributions of soil factors to the R. pseudoacacia population were in the order of available N > pH > available P. The regression models obtained in the study are expected to be useful in providing guidance to the reforestation of R. pseudoacacia population at ecoreclamation areas.

 

Effect of ciprofloxacin and copper combined pollution on the early growth of wheat.

QI Yu-shan, ZHANG Wei**, LIU Ming-da, YANG Dan, YAN Ying, HE Na

2014, 33(9):  2376-2381. 

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The effect of soil exogenous ciprofloxacin and copper combined pollution on the early growth of wheat was studied by the toxicological diagnosis method of higher plant. The potential ecological risks of soil contamination derived from livestock manure were investigated. Results indicated the early growth indexes of wheat expressed different degrees of responses to single copper or ciprofloxacin exposure. The wheat shoot and root length were mainly inhibited, while the seed germination rate was unaffected. The sensitivities of the three indexes to the two pollutants were in order of shoot length > root length > germination rate. Ciprofloxacin and copper combined pollution showed different effects on the wheat roots and shoot length. Compared with single copper exposure, inhibition effect on wheat root length was enhanced by the combined treatment of 20 mg·kg^-1 copper and 80 mg·kg^-1 ciprofloxacin, showing a synergistic effect, while the inhibition effect on wheat shoot length by the addition of 200 mg·kg^-1 of copper eased after ciprofloxacin addition, showing an antagonistic effect. The complex, produced by the interaction of ciprofloxacin and copper, may be the cause of various biological effects.

 

Chlorophyll biosynthesis metabolism of goldenleaf plants to SO₂ stress.

WANG Ling, DENG Lin-ying, LI Xi**

2014, 33(9):  2382-2387. 

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In order to understand the effects of SO₂ stress on chlorophyll biosynthesis of two goldenleaf shrubs (Ligustrum × vicaryi and Ligustrum japonicum  Howardii’) and investigate possible acting sites of SO₂ stress on chlorophyll biosynthesis, the activities of key enzymes involved in chlorophyll biosynthesis, the contents of chlorophyll and its intermediates were analyzed under different SO₂ treatments through an artificial static fumigation system. The results showed that the contents of Urogen Ⅲ, Proto Ⅸ, Mgproto Ⅸ, and chlorophyll a and b were increased with the rising of SO₂ concentration, then decreased at SO₂ concentration of 80 mg·m^-3. Furthermore, the activities of ALAD and UROS exhibited a similar trend. In contrast, the contents of ALA and PBG in the control were significantly lower than under the 20 and 40 mg·m^-3 treatments, and greatly higher than under 80 mg·m^-3. The results also indicated that changes of these factors related to chlorophyll biosynthesis were greater in Ligustrum × vicaryi than in Ligustrum japonicum ‘Howardii’, which implied that the latter was more resistant to SO₂ stress than the former. All the results predicated that chlorophyll biosynthesis in leaves of two goldleaf species was presumably blocked at the step from PBG to Urogen Ⅲ under the SO₂ stress.


 

Physiological response of Saussurea ussuriensis to Pb stress in Pb polluted and nonpolluted areas.

WANG Yi-feng**, YUE Yong-cheng

2014, 33(9):  2388-2394. 

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A hydroponics was used to study the physiological response of Saussurea ussuriensis. to Pb stress. Two samples of S. ussuriensis were from a Pbpolluted area in Huixian and a nonpolluted area in Gannan, respectively. The aim was to explore the ecological adaptation mechanism of the two S. ussuriensis populations to Pb stress. The results showed that, at different Pb concentrations, the chlorophyll content of S. ussuriensis from the polluted area increased first and then decreased, while that from the nonpolluted area showed a decreasing trend. The antioxidase enzyme activity of both S. ussuriensis populations increased first and then decreased, but the resistance of S. ussuriensis from the polluted area was stronger. The MDA contents of both S. ussuriensis populations increased with Pb concentrations, but it was significantly higher in the nonpolluted group than in the polluted group. The soluble protein contents of both S. ussuriensis populations decreased, being significantly higher in the polluted group than in the nonpolluted group. The variations in physiological indexes of S. ussuriensis from the polluted area indicated an adaptive evolution, forming a heavy metalresistance ecotype.

 

Potassium balance in the agroecosystem of the main cropping systems in Hubei Province.

XIA Ying, LIU Dong-bi, ZHANG Fu-lin, XIONG Gui-yun, DUAN Xiao-li, WU Mao-qian, FAN Xian-peng**

2014, 33(9):  2395-2401. 

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During 2010-2011, 10 field trials were conducted with 6 main cropping systems to study the potassium input, output and balance in Hubei Province. The results showed that the annual average rates of K input to the agroecosystems by fertilization, rainfall, irrigation and straw return were 129.8, 10.3, 14.9 and 30.1 kg·hm^-2, respectively. It indicated that rainfall, irrigation and straw return played an important role in soil K input. Potassium outputs from soils by harvest and runoff were 211.2 and 26.4 kg·hm^-2, accounting for 88.5% and 11.5% of total K output, respectively. The rate of K removed by straw was 186.3 kg·hm^-2, accounting for 89.1% of total harvest. However, only 16.2% of that was returned to the field. This suggested that a large proportion of K was carried off by straw from the agroecosystems. In other words, the potential of input K by straw return to field is huge. Soil K is deficit in the main cropping systems in Hubei with an average of -52.4 kg·hm^-2. Therefore, to improve the K balance in the agroecosystems of Hubei, it is practical to increase K fertilization, through promoting the K input through rainfall and irrigation, and the return of straw to the field.

The responses of photosynthetic physiology in macroalga Ulva linza to temperature variation under ocean acidification.

LIU Ya-meng1,2, TANG Zhen-ming1, LI Xin-shu1, YANG Zi1, YAO Dong-rui3, LIU Zhao-pu2, XU Jun-tian1**

2014, 33(9):  2402-2407. 

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In this study, the green alga Ulva linza was selected to assess the effects of temperature on macroalgae under the ocean acidification condition. The juvenile U. linza was _cultured at two CO₂ concentrations \[normal, 390 μL·L^-1 (LC); elevated, 1000 μL·L^-1 (HC)\] and at 20 ℃, then the response of photosynthetic physiology of adult algae to temperature changes (5, 10, 15, 20, 25 and 30 ℃) was measured. Our results showed that high CO₂ significantly enhanced the relative growth rate of U. linza, with the enhancements of the nitrate reductase activity and respiration rate (R_d), although the net photosynthetic rates were not significantly changed. Moreover, the contents of Chl a and Chl b significantly decreased when the algae was cultured at the high CO₂ level. An instantaneous change in temperature resulted in different photosynthetic performance at the different CO₂ concentrations. When the temperature decreased, the maximum photosynthetic rate (P_max), respiration rate （R_d), light saturation point (I_k) and light compensation point (I_c) were reduced. However, photosynthetic efficiency (α) increased first and then decreased with the increase of temperature. High CO₂ concentration significantly enhanced α, R_d and I_c compared to the control treatment. P_max and I_k were enhanced with the temperature increase, while α, R_d and I_c showed an opposite trend. Moreover, α and R_d at high temperature were higher in HCgrown algae than in LCgrown algae, but I_c was lower in HCgrown algae. Compared to the LCgrown algae, the HCgrown algae had a better ability to adapt high temperature.

Effects of different treatments on seed germination and seedling establishment of eelgrass Zostera marina L.

TIAN Lu, ZHANG Pei-dong**, NIU Shu-na, ZHANG Xiu-mei, ZHANG Ling-yu

2014, 33(9):  2408-2413. 

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Seed germination and seedling establishment of eelgrass Zostera marina L. exposed to acupuncture, acid, drug, hormone, low salinity, fluctuating temperature, and low temperature stratification were studied under controlled laboratory conditions. Results showed that, after 30 d of seed germination, low salinity had a significant effect on the seed germination of Z. marina (P<0.05). The germination rate and germination index (GI) of seeds under the salinity of 25 were 36.3 times and 58.9 times as high as those of seeds from the control group (0.67% and 0.07), while the mean timetogerminate (MTG) was lowered down to 9.3 d. Seed germination rate and GI gradually increased as salinity decreased, whereas an opposite trend was observed in MTG. In addition, acupuncture significantly promoted seed germination, as the germination rate and GI of the seeds in this treatment were 26.9  and 42.7 times as high as those of the seeds in the control group, whereas MTG was lowered down to 12.6 d. However, seed germination was not significantly affected by acid, hormone, drug, fluctuating temperature, and lowtemperature stratification. By contrast, the establishment rate of seedgenerated seedlings was significantly higher in the lowsalinity treatments (with salinity of 10-25) than in the control treatment. However, no obvious difference in morphology was found between these treatments. The seedgenerated seedlings in the acupuncture treatment all died at the end of the experiment (30 d). The results indicated that low salinity could promote Z. marina seed germination, and the optimum salinity range for rapid seed germination is from 10 to 25.

 

Effects of moderateintensity harvesting on interspecific competition between Potamogeton crispus and Elodea nuttallii.

ZUO Jin-cheng1,2, HE Feng2, MA Jian-min2, ZHOU Qiao-hong2, ZENG Lei2, KONG Ling-wei2, HU Sheng-hua2, WU Zhen-bin2**

2014, 33(9):  2414-2419. 

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A replacement series experiment was carried out to analyze the effects of moderateintensity harvesting on interspecific competition between Elodea nuttallii and Potamogeton crispus. Competition indices such as aggressivity, relative yield, relative competitive intensity and relative crowding coefficient showed that E. nuttallii was the stronger competitor before and after harvesting. P. crispus outcompeted E. nuttallii significantly (P<0.05) in coverage in both the monoculture and the mixed culture before harvesting. However, harvesting resulted in a significant reduction in coverage of P. crispus by 33.5% in the monoculture and 45.3% (P<0.05) in the mixed culture, respectively, and a significant increase in coverage of E. nuttallii (P<0.05). The result showed that E. nuttallii surpassed slightly over P. crispus in terms of coverage. The mean dry weight per plant of P. crispus was greater than that of E. nuttallii in both the monoculture and the mixed culture before harvesting (P<0.05). However, the mean dry weight per plant of P. crispus was obviously lower than that of E. nuttallii after harvesting in both the cultivation modes (P<0.05). The moderateintensity harvesting produced inhibition effects on P. crispus but promotion effects on E. nuttallii in branching and dry matter accumulation in layers of 0-25 cm and above, which would be beneficial for E. nuttallii to win the competition with P. crispus. In addition, the results also showed that root growth was less affected by the interspecific competition.

The community structure of macrozoobenthos and biological assessment of water quality in the Irtysh River of Xinjiang.

WANG Jun1,2, ZHOU Qiong1,2**, XIE Cong-xin1,2, LI Jun1,2, WEI Li-li1,2

2014, 33(9):  2420-2428. 

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Irtysh River in Xinjiang Uygur Autonomous Region is the only river in China that disgorges into Arctic Ocean and tremendously abundant in natural resources of zoobenthos throughout the drainage basin. In the present study, we conducted an investigation on the community structure of macrozoobenthos in Irtysh River in July, August and October 2012 and May 2013, which focused on the mainstream, five main tributaries and one affiliated reservoir. We identified 117 macrozoobenthos species, of which 106 species were aquatic insects (90.6%), 6 species were Mollusca (5.1%), 3 species were Oligochaetas (2.6%) and 2 species belonged to other macroinvertebretes (1.7%). The dominant species were composed primarily of Cinygmula sp., Baetis sp., Orthocladius sp., Ephemeridae sp., Polypedilum sp., Apedilum sp., Limnodrilus hoffmeisteri, Cheumatopsyche sp., Ephemerella sp., and Diamesa sp. The density (P=0.558) and biomass (P=0.464) of macrozoobenthos showed no significant seasonal difference. The average density and biomass of macrozoobenthos were 519.05 ind·m^-2 and 3.30 g·m^-2, respectively. The density showed a significant spatial difference, with a higher mean value in the upstream (604.53 ind·m^-2) than in the downstream (447.82 ind·m^-2). Annual mean values of Margalef, Shannon, Simpson and Pielou’s indices were 1.12, 0.53, 0.65 and 0.52, respectively. Clustering analysis was applied for assessing the diversity status of macrozoobenthos at different sampling sites of Irtysh River. The results showed that the community structure of macrozoobenthos was divided into two types: (i) one group had low diversity index at sampling sites 1, 6, 8 and 9; (ii) the other group exhibited relatively high diversity at other sampling sites. Based on the biological indices (FBI index, Beck Index, BMWP index and Chandler score system (CS)) of macrozoobenthos, water quality in Irtysh River was assessed. The results indicated that the water quality in Irtysh River was characterized as slight pollution. Spearman correction analysis showed that the distribution of aquatic insects was correlated positively with water transparency. Oligochaeta was correlated positively with salinity, conductivity and total dissolved solid (TDS), and had a negative relation with resistance. There was no significant relationship between the distribution of Mollusca and environmental factors.

 

Effects of abrupt salinity stress on gill 14-3-3a, NKCCla, Apo-14 and Na⁺-K⁺-ATPaseβ expression of Mugil cephalus.

JIANG Mei**, LILei, SHEN Xin-qiang, WU Qing-yuan, NIU Jun-xiang

2014, 33(9):  2429-2435. 

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To explore the response of gene expression of gill 14-3-3a, NKCCla, Apo-14 and Na⁺-K⁺-ATPaseβ in Mugil cephalus to salinity stress, polymerase chain reactionrestrained fragment length polymorphisms technique was applied. We found that NKCCla and Na⁺-K⁺-ATPaseβ protein synthesis was induced at the low salinity stress, with an obvious increase in expression level (P<0.01). However, the 14-3-3 gene mRNA expression level and Apo-14 gene mRNA expression level descended at the low salinity stress (P<0.05). The comprehensive evaluation index of multiple biomarkers was established based on the integrated biomarker responses (IBR). The IBR values of each gene indicated that the NKCCla and Na⁺-K⁺-ATPaseβ genes were suitable molecular biomarkers of the fish gill tissue for salinity stress assessment.

Optimal temperature for hsp18.2 promoter in gene expression of anthocyanin biosynthesis of Antirrhinum majus.

SONG Qian-na1,2, LIU Chen1, GAO Zhen-rui1,2, LI Ying1,2, ZHANG Chi1,2, CUI Min-long1**

2014, 33(9):  2436-2441. 

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To clarify the impact of temperature change on gene expression in roots, we made a plant expression vector pBIPhsp::ROS, which harbors a MYB gene Rosea1 controlling anthocyanin biosynthesis in Antirrhinum majus and the promoter of small heatshock protein 18.2 of Arabidopsis. We obtained hairy roots by genetic transformation. Moreover, we investigated the impact of temperature change on gene expression in roots. The results showed that anthocyanin accumulations were observed in the transgenic hairy roots under treatment of 37, 40 and 42 ℃ for 4 h, and the deepest coloration was detected in the treatment of 42 ℃ for 8 h. In addition, by the method of RT-PCR, the expression of Rosea1 was detected in the hairy roots treated at 37, 40 and 42 ℃, and a significant correlation between expression pattern and anthocyanin accumulation was found. Therefore, our result suggests that the pBIPhsp::ROS is a useful marker and a tool for the study of the effect of temperature change on gene expression in roots.

Poison effect of “Mie fei ling” on the alien Nile tilapia (Oreochromis niloticus).

MA Guang-ming1,2, GU Dang-en1, Mu Xi-dong1, LUO Jian-ren1, HU Yin-chang1**

2014, 33(9):  2442-2447. 

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Nile tilapia (Oreochromis niloticus) has successfully invaded many areas of the world, threatening the survival of native fish and the structure and function of the water ecosystem. In order to control the population of the Nile tilapia in wild conditions, an organophosphate drug called “Mie fei ling” was screened out for the specific toxicity on Nile tilapia. In this study, the effect of “Mie fei ling” on Nile tilapia and other common fish was verified through the acute toxicity test. Meanwhile, the median lethal concentrations of “Mie fei ling” to the Nile tilapia (length, 4.0±0.3 cm; wet weight, 2.5±0.4 g) at 24, 48, 72 and 96 h were determined by the method of semistatic test, and the safe concentration in the environment was also estimated. The result showed that “Mie fei ling” had significant effects on poisoning the Nile tilapia (P<0.01). The Nile tilapia exposed to “Mie fei ling” 0.10, 0.17 and 0.20 mg·L^-1 for 96 h all died, while the other species including the grass carp (Ctenopharyngodon idellus), mud carp (Carrhina molitorella), crucian carp (Carassius auratus), loach (Misgurnus anguillicaudatus), zebrafish (Danio rerio), and the White Cloud Mountain minnow (Tanichthys albonubes) swam normally with no symptoms of toxicity. The 24 h, 48 h, 72 h and  96 h LC₅₀ values of Nile tilapia were 0.167, 0.077, 0.057 and  0.043 mg·L^-1 respectively and the safe concentration was 0.0043 mg·L^-1. These results suggested that “Mie fei ling” could be used to specifically control the wild Nile tilapia population in small water bodies.

 

Influence of hypoxia stress on physiological metabolism of Ruditapes philippinarum.

ZHANG Wen-bin1,2, LU Zhen-bo1, ZHANG Ying1**, CHEN Jian-qiang1, LI Fan1, ZHENG Liang1,2, CONG Xu-ri1,2

2014, 33(9):  2448-2453. 

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In order to detect the pathologic changes of tissue structure in clams (Ruditapes philippinarum), the hematoxylineosin stain (H－E) method was employed after 20 days of exposure to hypoxia (DO <2 mg·L^-1) stress. Oxygen consumption, ammonia excretion rate, CO₂ production and O:N ratio was also measured in clams exposed to hypoxia on the 2nd, 5th, 10th and 20th day. The results showed that a visible structural difference was observed between the hypoxia and control groups. Scattered deeppurple round spots distributed in the clam tissues of the hypoxia group, which might be due to abnormal lipid metabolism to form the lipid accumulation in the clams exposed to hypoxia. At 22 ^oC water temperature, oxygen consumption, ammonia excretion rate and CO₂ production of clams were significantly affected by hypoxia stress. The rates of oxygen consumption, ammonia excretion and CO_2 production of the clams decreased when exposed to hypoxia on the 2nd day, with their values being 0.566 mg·g^-1·h^-1, 0.079 mg·g^-1·h^-1 and 26.236 mg·g^-1·h^-1 respectively. The oxygen consumption and ammonia excretion rates reached the lowest level on the 2nd day. But the CO₂ production rate reached the lowest value (7.422 mg·g^-1·h^-1) on the 20th day, which was about one half compared to the control group. The O:N ratio was 6.25-12.11 in the hypoxia group, and it reached the maximum value of 12.11 on the 20th day. Therefore, hypoxia had an important impact on the tissue structure and physiological metabolism in clams. The results could provide a theoretical basis for the scientific management of clam’s aquaculture.


 

Effects of mixture of forest litter on nutrient contents and functional diversity of microbial community in soil.

SONG Meng-ya1, LI Zhong-pei1,2**, LIU Ming1, LIU Man-qiang3, JIANG Chun-yu1

2014, 33(9):  2454-2461. 

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Litter is one of the most critical components in forest ecosystem, and plays a key role in ecosystem functioning. Investigating the influences of litter on soil will not only help understand the forest ecosystem functional traits, but also facilitate to provide theoretical basis for scientific management measurements. In this study, three types of litter including Pinus massoniana needles, Quercus chenii leaves and Imperata cylindrica stalks and leaves were used in a laboratory microcosm experiment. Ten treatments were designed, through incorporation of different proportions of the three kinds of litter at an overall loading level of 1% (relative to soil weight). After 180 days of incubation, soil physicochemical and biological properties were measured. Results showed that soil pH values were significantly increased after litter addition regardless of litter treatments. Moreover, soil pH in the mixed litter treatments was consistently higher than that in the single litter treatments. Cumulative CO₂ emissions and C mineralization rate of the threespecies mixed (1∶1∶1) treatment increased by 30.48% (P<0.01) and 29.69% (P<0.01) compared to the weighted average of the three single litter treatments, respectively. BIOLOG analysis showed that the average well color development (AWCD) of the P. massoniana needles + Q. chenii leaves (1∶1) treatment was the highest among all treatments. The significant alteration and carbon utilization potential pattern implicated the modifications of microbial community structure due to the amendment of different litter. The responses of soil process to different types of litter combination may be vital to the maintenance of forest soil quality, mitigation of global change, and appropriate mixture and matching of plant species.

Influence of vegetation construction on the soil moisture in northern China: A meta analysis.

LI Gang1,2**, LIU Li-chao1, GAO Yan-hong1, YANG Hao-tian1,2, WANG Yan-li1,2

2014, 33(9):  2462-2470. 

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Vegetation construction is the most effective way to control erosion by wind and water in the arid and semiarid regions of northern China. Reasonable vegetation construction needs to consider the vegetation carrying capacity of soil water. Based on published literatures of soil water change following revegetation in the arid and semiarid regions of northern China, this paper analyzed the influences of two kinds of vegetation construction (trees and shrubs) on soil water at different depths using a metaanalysis. The results showed that vegetation construction produced prominent negative effects on soil water in deep layers (below 40 cm, with an effect size of -0.40). Tree planting resulted in a significant decrease in soil water (effect size: -0.58), while shrub planting had a negative effect on soil water (effect size: -0.27) though no significant influence was found. According to the subgroup analysis, tree plantations in the zones with precipitation of more than 400 mm and with the stand ages of less than 20 years led to decline of soil water (effect sizes: -0.62 and -0.69, respectively). The results indicated that tree planting produced more negative influences on soil water environments than shrub planting, and shrub planting could improve soil wateruse efficiency in the arid and semiarid regions.

Characteristics of nitrogen and phosphorus loss by surface runoff in Moso bamboo stands in northern Zhejiang Province.

WANG Qing-bing1, LI Ze-bo1, ZHANG Jian-feng1**, CHEN Guang-cai1, WU Hao1, SUN Hui1, WANG Li1, PAN Chun-xia2

2014, 33(9):  2471-2477. 

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Nitrogen (N) and phosphorus (P) migration and transformation are complex in the watersoil interface. It is significant to probe the characteristics of N and P losses in watersheds for managing nonpoint source pollution. In this paper, five runoff plots (5 m×20 m) were set to examine runoff in a Moso bamboo (Phyllostachys edulis) forest stand around the Fushi Reservoir watershed in northern Zhejiang Province from May 2012 to October 2013, and the migration characteristics of N and P losses were analyzed in the Moso bamboo forest stand. The results showed that, in the 16 observed surface runoff events, the differences in surface runoff amount were obvious among the different plots, with the maximum runoff being 0.98 m3. N was the main lost nutrient element in the Moso bamboo forest stand. The concentrations of NO₃^--N, NH₄⁺-N, TN and TP in the runoff water ranged from 0.039-1.017, 0.039-2.547, 2.069-5.393 and 0.020-1.205 mg·L^-1, respectively. These variables were greatly influenced by the rainfall and runoff water. Moreover, the correlation between N or P loss and runoff amount was properly fitted by a quadratic equation. On October 12th, 2012, due to typhoon “FITOW”, the runoff reached the maximum with an average of 0.81 m³, and the losses of TN and TP were 2.300 and 1.716 g, respectively. Hence, we concluded that during the period of plant nongrowing season and heavy rain, there was a great risk of N and P losses with runoff in this region, causing potential nonpoint source pollution around the Fushi Reservoir.

Changes in soil water under different macrophanerophyte covers in the gully region of Loess Plateau in northwest Shanxi.

ZHANG Min1, NIU Jun-jie1,2**, LIANG Hai-bing1, SHI Jian-wei1, GUO Biao3

2014, 33(9):  2478-2482. 

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Macrophanerophytes play an important role in soil and water conservation in the gully region of Loess Plateau. In this study, the moisture dynamics of soils covered with three macrophanerophytes of Populus cathayana, Salix matsudana, and Pinus tabuliformis in Wuzhai, Northwestern Shanxi were investigated by soil drilling and drying methods. Results showed that the soil moisture in the 0-600 cm depth had great differences among the three macrophanerophytes during the early growing season (April to May). The soil moisture of the three macrophanerophytes was in order of: P. cathayana > S. matsudana > P. tabuliformis. Soil moisture in profile of the three macrophanerophytes in 0-600 cm increased initially, then gradually reduced, finally stabilized with increasing the soil depth. The degree of drought of the soil layer among the three macrophanerophytes types was in the order: P. tabuliformis > S. matsudana > P. cathayana. Coefficients of variation of soil moisture contents of the three macrophanerophytes varied in different depth ranges: P. tabuliformis > P. cathayana > S. matsudana in depths of 0-100 cm and 400-500 cm, S. matsudana > P. cathayana > P. tabuliformis in depths of 100-200 cm and 500-600 cm, and P. cathayana > S. matsudana > P. tabuliformis in depths of 200-400 cm. Concerning with the influence of macrophanerophytes on the soil water balance and the regional hydrological cycle, the three macrophanerophytes were unsuitable in the gully region of Loess Plateau.

Effects of forest gaps on soil nitrogen dynamics in seasonal freeze-thaw transition in an alpine forest of western Sichuan.

YIN Rui, XU Zheng-feng, WU Fu-zhong, GOU Xiao-lin, XIONG Li, TANG Shi-shan, XIE Cheng-han, YANG Wan-qin**

2014, 33(9):  2483-2489. 

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In order to understand how forest gaps affect soil nitrogen dynamics, we estimated the dynamics of several soil nitrogen forms (ammonium nitrogen, nitrate nitrogen, microbial biomass nitrogen and dissolved organic nitrogen) over the four crucial periods (early-freezing period, deep-freezing period, early-thawing period and late-thawing period) through setting up four gap treatments (large gap, medium gap, small gap and under canopy) in an alpine Abies faxoniana forest of western Sichuan in the winter of 2012-2013. The results showed that, the contents of soil ammonium nitrogen and nitrate nitrogen were significantly higher in the late-thawing period than in the three other crucial periods; microbial biomass nitrogen was lowest in the early-thawing period, and soil dissolved organic nitrogen content was the minimum in the deep-freezing period, while both of which were the highest in the early-freezing period; soil nitrate content was high, accounting for 67.26%-83.59% of total soil mineral nitrogen. Forest gaps would change soil microenvironment and then change nitrogen components in winter. The size of forest gaps had a significant positive correlation with the dissolved organic nitrogen content; soil temperature was significantly positively correlated with ammonium, nitrate and dissolved organic nitrogen contents; while the soil freezing depth was significantly negatively correlated with soil nitrate and dissolved organic nitrogen contents. More mineral nitrogen and dissolved organic nitrogen were in the small gap and under canopy than in the large and medium gaps through seasonal freeze-thaw transition, thus creating a good growing condition for vegetation and soil microbes in growing season.

 

The morphological and anatomical characteristics of ectomycorrhizae colonizing Tilia amurensis Rupr. in Heilongjiang Province.

CUI Lei, MU Li-qiang**

2014, 33(9):  2490-2500. 

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As a national Ⅱ protected plant in China, Tilia amurensis Rupr. is an important tree species for nectar source, medicine and landscape. The resources of ectomycorrhizae colonizing T. amurensis were investigated in three typical distribution areas of T. amurensis in Heilongjiang Province. A total of 18 ectomycorrhizal types were grouped by observing morphological and anatomical characteristics of T. amurensisassociated ectomycorrhizae, of which 13 were formed by basidiomycetes, 1 by ascomycytes, and 4 unknown. Our study provides a morphological basis for mycorrhizal seedlings of T. amurensis.

Ecological benefits of roadside greening vegetation in Shanxi Province.

WANG Hui1, REN Jian-zhong2, GUO Jin-ping1**, ZHANG Yun-xiang1

2014, 33(9):  2501-2509. 

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To investigate the ecological services and economic benefits of roadside treebelts in Shanxi Province, sampling points were set up in typical roadside treebelts with varied stand structures and different distances from roads to record dispersion patterns of SO₂, NO₂ and dust, noise attenuation and daily temperature variation. The recorded data were then analyzed according to major stand characteristics, such as species composition, stand density, canopy density, degree of porosity and LAI to construct estimation models for ecological services of roadside treebelt. Moreover, reduction of SO₂, NO₂, dust and noise, carbon fixation and oxygen release of roadside greening vegetation in Shanxi Province were estimated based on the models. The economic benefits of roadside treebelt in terms of their ecological services were also calculated. The results showed that the effective green coverage of main highway landscaping projects in Shanxi Province was 29194.29 hm² by 2011 with carbon storage of 887343.6 t in total. The calculated economic losses avoided by the roadside greening vegetation were about 543000, 487000, 4421000, 987000 and 214000 RMB per year in terms of SO₂ reduction, NO₂ reduction, dust reduction, noise reduction and temperature reduction, respectively. Furthermore, the calculated economic benefits generated by these roadside greening vegetations were about 262713000 and 77441000 RMB per year in terms of carbon fixation and oxygen release. In total, the economic benefit provided by roadside greening vegetation in Shanxi Province was about 0.347 billion RMB annually.

 

Purification efficiency of domestic wastewater by  mangrove constructed wetlands.

YANG Qiong1,2,3, LAN Chong-yu2, TAM Fung-yee3,4**, CHEN Li-e1, HU Liu-liu1

2014, 33(9):  2510-2517. 

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Three identical belts (length: 33 m, width: 3 m, depth: 0.5 m) of subsurfaceflow wetland were constructed, and each was planted with one of three different mangrove plants \[one exotic mangrove species (Sonneratia caseolaris) and two native species (Kandelia obovata and Aegiceras corniculatum)\]. The hydraulic loading rate was 5 m³·d^-1 and the hydraulic retention time was three days. The study was lasted for 2 years. The average removal efficiencies were 65%, 74%, 53%, 52%, 67% and 70% for chemical oxygen demand (COD_cr), biochemical oxygen demand (BOD₅), total nitrogen (TN), ammonianitrogen (NH₃^- -N), total phosphorus (TP) and soluble phosphate (SP), respectively. The treatment efficiency was positively correlated with plant growth. At the beginning of the study, S. caseolaris had the fastest growth and best purification efficiency. However, half of S. caseolaris were dead due to an accidental spillage of herbicides few months after the start, the treatment efficiency of S. caseolaris was then dropped and became lower than that of A. corniculatum and K. obovata. More than 80% of total coliform and fecal coliform were removed and no significant differences were found among the three mangrove species, but the average concentrations in the treated effluents were still higher than the discharge standard set by the state government. The results indicated that a posttreatment process to remove coliforms must be included if the  mangrove constructed wetland is used for domestic sewage treatment. As for S. caseolaris, further research is needed to understand its sensitivity to chemicals and low temperature.

Spring drought damage risk analysis and zoning of melon and vegetables in Hainan Province.

ZHANG Lei1,3, HUO Zhi-guo1,2**, HUANG Da-peng4, JIANG Yan5, YU Cai-xia1, WU Li1

2014, 33(9):  2518-2527. 

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Using the 18 meteorological stations observation data as well as the yield and planted area data of melon and vegetables in Hainan Province during 1998-2011, a spring drought grade index system was constructed based on the comprehensive drought index using precipitation, dry days, continuous dry days and maximum continuous dry days during March and April. Damage loss induced by spring drought was separated from the total yield reduction rate. A comprehensive drought risk model of melon and vegetables (watermelon, cowpea, paprika, luffa) was built by integrating with hazard index, damage environment, damage loss and damage prevention capability. The results showed a high spring drought hazard index occurred in the eastern and western parts of Hainan while a low index in the central regions, and the risk probability of different grade hazard indices differed with regions. Damage environment index decreased from Wuzhishan district to the periphery. Drought damage loss and prevention capability differed in different regions. The high comprehensive drought risk index of melon and vegetables mainly occurred in the western and southern parts of Hainan, while the low index in some central and eastern regions. Our results provide useful information to a better understanding of drought risk for melon and vegetables and help for the policymaking of disaster risk management.

 

Extreme precipitation events in Pearl River Basin in relation to the atmospheric circulation during 1960-2012.

ZHAO Yi-fei, ZOU Xin-qing**, XU Xin-wang-hao

2014, 33(9):  2528-2537. 

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Based on daily precipitation data at 42 meteorological stations over Pearl River Basin observed by the China Meteorological Administration during 1960-2012, the methods of linear regression, correlation analysis and rescaled range analysis method (R/S) were employed to analyze the temporal variability and spatial distribution of extreme precipitation, and its extreme climatic variation in future was predicted. Eleven indices of extreme precipitation were studied. The results showed that wet day precipitation had decreased by -7.2 mm·10 a^-1, while the maximum 1day precipitation, maximum 5day precipitation, very wet day precipitation and extremely wet day precipitation showed statistically increasing trends at rates of 1.1, 0.8, 5.3 and 3.9 mm·10 a^-1, respectively. Meanwhile, simple daily intensity index also showed an increasing trend by 0.2 mm·d^-1·10 a^-1. The number of heavy precipitation (10 mm) days had an insignificant decreasing trend at the rate of -0.40 d·10 a^-1, while heavier (20 mm) and heaviest (25 mm) precipitation days had a weak increasing trend at the rates of 0.05 and 0.1 d·10 a^-1, respectively. Consecutive dry days had an increasing trend and consecutive wet days had a decreasing trend at the rates of 1.1, -0.2 d·10 a^-1, respectively. Spatial variations of precipitation extreme indices showed obvious differences, and they were not clustered either. On the whole, the number of rainy days had decreased over the YunnanGuizhou Plateau and hilly Guangxi, and the spatial distribution reflects the regional climatic complexity. R/S analysis showed that the future trends of extreme precipitation events were consistent with the past. In addition, except for consecutive dry days, the other extreme precipitation indices have significant correlations with annual precipitation. Large scale atmospheric circulation changes derived from NCEP/NCAR reanalysis reveal that strengthening anticyclonic circulation over the Eurasian continent and weakening East Asian summer monsoon have contributed to the increase in precipitation extremes in the Pearl River Basin.

Climate sensitivity differences of stable carbon isotope in different components of tree ring: Research progress and synthesis.

ZHAO Ye-si, WANG Jian**, SHANG Zhi-yuan

2014, 33(9):  2538-2547. 

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It is helpful to identify the components of tree ring in which δ¹³C is most sensitive to climate change by comparing the correlations between the δ¹³C sequence and climate variables. Sensitivities of δ¹³C response of the components (e.g. whole wood and cellulose) to climate change vary among tree species or regions, and most research attributes this variation to the interference caused by components in xylem. It can be concluded that δ¹³C of both whole wood and cellulose significantly responses to climate change in following cases: 1) deciduous species; 2) trees with low contents of extractives and less influenced by lignin (e.g. Quercus); 3) regions where tree growth is strongly restricted by climate. In the latter case, δ¹³C of cellulose shows stronger sensitivity to climate change in evergreen conifers with higher extractive contents, compared to that of whole wood. In addition to the components in xylem, the factors, such as special physiological processes of trees and climate limitation on tree growth, affect the response sensitivities of δ¹³C in different components to climate change, and their action mechanisms should be further explored. Meanwhile, more studies should be focused on the interference degree of single xylem components on the correlation between δ¹³C of whole wood and cellulose for different species or regions. Sensitivities of δ¹³C response of different components to climate change should also be strengthened in the subtropical monsoon regions of southeast China.

 

Urban ecosystem nitrogen metabolism: Research progress.

XIAN Chao-fan1，2, OUYANG Zhi-yun1**

2014, 33(9):  2548-2557. 

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Currently, urban nitrogen metabolism is a hotspot of the urban metabolism research, the framework of which is to regard the urban region as an organism of nitrogen metabolism, exploring the human impacts on the process of the anthropogenic reactive nitrogen metabolism in urban regions as well as the related potential environmental problems. Based on elaboration of the concept and the research background of urban nitrogen metabolism, this paper attempts to introduce the progress of the research of urban nitrogen metabolism by application of material flow analysis, and to reveal the prospect of the modeling research of urban nitrogen metabolism by application of system dynamics models. Finally, the future development in the research of urban nitrogen metabolism is discussed from three perspectives as follows: The nitrogen metabolism analysis within an urban region, the fate of industrial nitrogen in urban nitrogen metabolism, and the application of nitrogen footprint in the research of urban nitrogen metabolism. The definition in the boundaries of survey regions and the fate of nitrogen flows is the key to accurately analyze the processes of urban nitrogen metabolism at different scales. At present, there are few researches on the analysis of the urban nitrogen metabolism in China. Therefore, to explore the methods of multiscale analysis and the indexes for evaluation of the urban nitrogen metabolism can provide theoretical support for the reduction of anthropogenic reactive nitrogen emissions in urban
regions.

The effect of adsorbing fine particulate matter (PM_2.5) by garden plants: A review.

CHEN Xiao-ping1, JIAO Yi-wen1, PEI Ting-ting1,2, ZHOU Zhi-xiang1**

2014, 33(9):  2558-2566. 

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Garden plants have a significant ability to remove air particulate matters (PM) and can effectively improve the urban environmental quality. The study of dustretention effect of garden plants in China and other countries have made considerable achievements so far. However, most researches on the dustretention effect of garden plants had been primarily concentrated on the total suspended particulates (TSP) and coarse particles (PM₁₀), while few studies have focused on the effects of plants’ adsorbing air fine particulate matter (PM_2.5). In order to provide references for further study in the PM_2.5 adsorption capacity and adsorption mechanism of garden plants, we have concluded that the effects of garden plants’ adsorption of PM_2.5 according to different perspectives, i.e., the way of plant leaves absorbing air particles, the transfer process of PM_2.5 upon leaves and the PM_2.5 adsorption periodicity of plant leaves, the characteristics of adsorption of plant leaves to different diameter particles, the garden plants’ ability and mechanism of adsorbing PM_2.5. Additionally, we propose that the key points and trends about garden plants absorbing PM_2.5 based on three aspects: the quantitative analysis method of PM_2.5 removal efficiency of garden plants, the measurement and evaluation of garden plants’ adsorption abilities to PM_2.5, selection of plants with a higher ability to adsorb PM_2.5, the mechanism and influencing factors of garden plants’ adsorption to PM_2.5. The present paper provides a basis for deepening the research on the mechanism of plant adsorbing PM_2.5 and selection of garden plants with a high ability of adsorption to PM_2.5.


 

Research progress on methane bio-oxidation process and methanotrophs in landfill.

MEI Juan1,2**, ZHAO You-cai2

2014, 33(9):  2567-2573. 

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Refuse landfill sites are one of the important methane emission sources, contributing 6%-12% of the anthropogenic emission of methane. The promotion of feasible methane emissionreduction techniques is an imminent challenge. Most recently, methane biooxidation through methanotrophs involved in landfill cover soil has been regarded as a potential strategy to mitigate fugitive methane emission from landfill. In this study, the recent developments of microbial mechanisms of methane biooxidation by landfill cover, modified methane biooxidation technologies and microorganisms associated with methane oxidation in landfill environment were critically summarized. According to the literature review, few studies have been carried out to decrease the methane release during landfill operation, which accounts for a great part of the total methane emission. Future research efforts should be thus dedicated to modification of methane oxidation capacities of the daily and middle covers.

Improvements of the diffusion method to measure inorganic nitrogen isotope of ¹⁵N labeled soil.

SUN Jian-fei1,2, BAI Edith1**, DAI Wei-wei1, PENG Bo1,2, QU Gui-fang1,2, JIANG Ping1

2014, 33(9):  2574-2580. 

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To date, the diffusion method which measures the isotope values of ammonium and nitrate of soil extraction is extensively applied. But we still lack a systematic method to evaluate the isotope discrimination effect in ¹⁵N labeled experiments, mainly due to the high ¹⁵N abundance and its variation during the incubation period. Here, we presented some efficient improvements of the diffusion method including using 10 μL KHSO₄ as the ammonia absorption liquid, setting the gas to liquid ratio to 4:1, lowering the use of MgO and Devarda alloy to 250 mg, and selecting 25 ℃ as the incubation temperature. We used this improved method to measure the inorganic nitrogen isotope abundance of solutions with both high and low nitrogen contents. The results indicated that there was no significant difference between theoretical and measured values. Therefore, our improvements are useful to measure ammonium and nitrate isotope ratios of ^15N labeled experiments.