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   Science & Technology Review
2011, Vol.29, No. 25
08 September 2011

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Science & Technology Review. 2011, 29 (25): 3-3. ;  doi:
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科技风云

Science & Technology Review. 2011, 29 (25): 7-7. ;  doi:
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Science & Technology Review. 2011, 29 (25): 8-8. ;  doi:
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Science & Technology Review. 2011, 29 (25): 8-8. ;  doi:
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Science & Technology Review. 2011, 29 (25): 10-10. ;  doi:
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Science & Technology Review. 2011, 29 (25): 12-12. ;  doi:
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Science & Technology Review. 2011, 29 (25): 84-84. ;  doi:
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科技事件

Science & Technology Review. 2011, 29 (25): 9-9. ;  doi:
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科技工作大家谈

Science & Technology Review. 2011, 29 (25): 11-11. ;  doi:
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Science & Technology Review. 2011, 29 (25): 15-18. ;  doi: 10.3981/j.issn.1000-7857.2011.25.001
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Spescial Issues

Ten-year-period Demonstration Project in Hunshandake Sandland and Prospect for the Future Development of Eco-stock Farming Industry

JIANG Gaoming;LIU Meizhen;NIU Shuli;LI Yonggeng;PENG Yu;LI Gang;SU Benying
Science & Technology Review. 2011, 29 (25): 19-25. ;  doi: 10.3981/j.issn.1000-7857.2011.25.002
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Abstract ( 348 )
In order to realize the national goal of "combating dust storm and desertification in northern Beijing-Tianjin region", since 2000, the Chinese Academy of Sciences has initiated a huge demonstration project in Hunshandake Sandland and Northern Beijing agriculture-pasture trans-zones. After 10 years' experiment in Hunshandake Sandland, great achievements are realized both ecologically and economically. Bayinhushu, the village where the demonstration project was conducted, has 72 household, 288 persons, and a sandland area of 8400hm2. The main landscapes include shifting sand dunes, semi-shifting sand dunes, fixed sand dunes, meadows, and wetlands. The serious land degradation has been controlled, plentiful sandland vegetation is recovered, and dust storms are ceased in the demonstration area. The local herdsmen have ended the history of buying forages during winter and early spring from the market, nowadays, they are able to sell the superfluous forages to the market. Herdsmen of Bayinhushu now have their own driveways, new houses, tap-waters, and bathrooms; the living standard is significantly improved. The largest demonstration base for "replacing livestock with poultry" in China's grassland has established. The successful restoration story of Bayinhushu, especially as the case of desertification prevention and biodiversity conservation, has been intensively reported by academic journals and/or media both nationwide and internationwide. The prestigious Science magazine once reported the project achievement as a great ecological event in its special column of News Focus. The US college textbook, Geology and the Environment (6e), also refers Hunshandake story as the successful case of dust storm controlling. The main approaches, achievements, and challenges involving the demonstration project after 10 years' operation are concisely reviewed. Suggestions that are based on the actual practices and go far toward the sustainable development of eco-stock farming industry in a large region of grassland, especially in the four main sandlands in China have been put forward.

Geographical Distribution, Ecological Position, and Formation Causes of Temperate Zone Sparse Forest in China

YU Shunli
Science & Technology Review. 2011, 29 (25): 26-29. ;  doi: 10.3981/j.issn.1000-7857.2011.25.003
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Abstract ( 342 )
China possesses various types of sparse forests. Except sparse forests in tropic regions of China, other two types of sparse forests are classified, namely, temperate zone spare forests and temperate zone mountain spare forests. In temperate zone of China, there are many types of sparse forests, such as Ulmus pumila sparse forest, Picea schrekiana sparse forest, Platycladus orientalis sparse forest, Juniperus rigida sparse forest, Pinus sylvestnis var. mongolica sparse forest, Larix tibetica sparse forest, Abies densa sparse forest, Cupressus gigantean sparse forest, Sabina tibetica sparse forest, Sabina wallichiana sparse forest, Sabina saltuaria sparse forest, Larix potaninii var. macrocarpa sparse forest, Cupressus torulosa sparse forest, Sabina convallium sparse forest, Pinus roxburghii sparse forest, Pinus yunnanensis sparse forest, Picea likiangensis var. balfouriana sparse forest, Ulmus macrocarpa sparse forest, and Ailanthus altissima sparse forest, etc. Sparse forest ecosystem is a transition between forest and grassland or shrub ecosystem. It belongs to a zonal vegetation type. Comprehensive ecological factors have determined its geographical distribution; however, the key factor is water (local rainfall amount). In the mainland of China from south to north, there are rain forests, season rain forests, evergreen broad leaf forests, summer green broad leaf forests, sparse forests, and grassland or shrubs along altitudinal gradient. From east to west, there are forests, sparse forest, shrubs, and grassland or meadow along longitudinal gradient. Compared with the distribution area of forests and grassland,the distribution of sparse forest occupies the smaller areas. Temperate zone sparse forests of China mainly distribute in the transition area between agriculture region and pasture region. Understanding the causes of sparse forest formation could give the help to select the best methods for ecological restoration.

Vegetation Biomass and Net Primary Production of Sparse Forest Grassland in Hunshandake Sandland

LI Gang;LI Yonggeng;LIU Meizhen;JIANG Gaoming
Science & Technology Review. 2011, 29 (25): 30-37. ;  doi: 10.3981/j.issn.1000-7857.2011.25.004
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Abstract ( 395 )
Terrestrial ecosystems are playing important roles in the global carbon cycling. However, the information is still limited with regard to the semiarid sandland, comparing with the thorough studies on forest and grassland. The biomass carbon storage, Net Primary Production (NPP), and Rain Use Efficiency (RUE) of Hunshandake Sandland, a semiarid sandy region in Inner Mongolia covered with vegetation of Siberian elm (Ulmus pumila L.) sparse forest grassland, were estimated. Six main habitats, i.e. fixed dunes, semi-fixed dunes, shifting dunes, lowland, willow scrub, and wetland, were compared with each other to analyze the patterns of carbon storage and NPP distribution. The average biomass (21.30Mg·hm-2) and NPP (11.06Mg·hm-2·a-1) of the sparse forest grassland are 90% and 59% higher than the mean level for the surrounding temperate grassland, respectively. Governed by the same climate, the RUE for sparse forest grassland ecosystem is almost twice than that for surrounding grassland. The ratio of below to above ground biomass is 2.9 in the sandland, the fact indicates that most of the vegetation carbon are stored in a below ground pool. Although trees are functionally critical for maintaining the integrity of sparse forest grassland, they only account for 10% and 1.3% of the biomass and NPP, respectively. The sparse forest grassland in Hunshandake Sandland should be recognized as a temperate savanna ecosystem which is distinctively different from typical temperate grassland in the same region indicated by the higher NPP and vegetation carbon storage. Well designed management and restoration efforts could potentially realize ecosystem services in both forage production and carbon sequestration.

Photosynthesis Characteristics of a Sand-fixing Pioneer Legume in Hunshandake Sandland

NIU Shuli;JIANG Gaoming
Science & Technology Review. 2011, 29 (25): 38-44. ;  doi: 10.3981/j.issn.1000-7857.2011.25.005
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Abstract ( 385 )
Hedysarum fruticosum var. lignosum is a superior species in the sand dunes of Hunshandake Sandland. Exploring the photosynthetic characteristics of this species will be helpful to reveal the adaptive mechanisms of the pioneer species in the sandy environment. The photosynthetic characteristics of H. fruticosum var. lignosum are monitored and compared with those of Salix gordejevii, a typical C3 species co-existing with H. fruticosum in semi-fixed or fixed sand dunes. The maximal photosynthetic rate (Pmax) and water use efficiency of H. fruticosum are approximately one times higher than that of S. gordejevii. H. fruticosum could endure high light and temperature at noon and has a high light saturation point and a low light compensation point. Except Ribulose-1.5-bisphosphate carboxylase (RuBPcase), the activities of photosynthetic carbon assimilation enzymes, such as phosphoenolpyruvate carboxylase (PEPcase), NAD-malic enzymes (NAD-ME), NADP-malic enzymes (NADP-ME), NAD-malate dehydrogenase (NAD-MDH), NADP- malate dehydrogenase (NADP-MDH), and pyruvate phosphate dikinase (PPDK), in H. fruticosum are at least four times greater than that in S. gordejevii, it is suggested that H. fruticosum might have a C4 photosynthetic syndrome. However, the stable carbon isotope analysis reveals that H. fruticosum has the δ13C value of -23×10-3, which is closed to that of C3 plants. Therefore, it is likely that H. fruticosum is either a C3-C4 intermediate species, or a C3 species displaying C4 metabolic characteristics in the habitat of sand dune. The involvement of C4 metabolism in H. fruticosum might account for its greater efficiencies for photosynthesis and water use, and allows H. fruticosum to colonize the shifting sand dune with high temperature, light intensity, and water stress.

Landscape Pattern of Elm Open Forest in the Center Part of Hunshandake Sandland

PENG Yu;JIANG Gaoming;GUO Luo;LIU Meizhen;XUE Dayuan
Science & Technology Review. 2011, 29 (25): 45-47. ;  doi: 10.3981/j.issn.1000-7857.2011.25.006
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Abstract ( 375 )
Remote sensing provides a powerful tool to study the quantitative and qualitative information of landscape pattern. In order to explore landscape pattern traits of elm open forest in the center part of Hunshandake Sandland, northern China, the number, area, and shape index of landscape patch for elm open forest have been analyzed through the method of field survey and 3S technological applications. Spectral heterogeneity of sample plots is calculated using Landsat satellite TM images (6 bands, spatial resolution of 30m). The results indicate that there exist 100606 landscape patches in the center part of Hunshandake Sandland. However, the area of most patches (77%) is smaller than 0.5hm2, and patch shape index reaches at 0.11 averagely. Furthermore, the relationship between area and its shape index is also simulated using software SPSS, it is indicated that patch shape becomes more complexity with the decrease of patch area. These facts indicate that landscape fragmentation in elm open forest in the center part of Hunshandake Sandland is very serious, and needs to be immediately protected.

Response Strategies of C3 and C4 Plants to Drought Stress in Hunshandake Sandland

LIU Meizhen;ZHANG Haimin;YANG Shan;DU Jiancai;GUO Cuiyan;JIANG Gaoming
Science & Technology Review. 2011, 29 (25): 48-53. ;  doi: 10.3981/j.issn.1000-7857.2011.25.007
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Abstract ( 415 )
It is widely reported that global climate change has affected on the growth and distribution of plants. In order to investigate the response of different photosynthetic functional plants to drought stress, C3 plants (Leymus chinensis) and C4 plants (Chloris virgata) are chosen from Hunshandake Sandland to experience drought stresses treatments. One treatment was that the plants were drought naturally for 10 days after a saturant watering; the second treatment was that the plants were drought naturally for 10 days with accepting dew at each night after a saturant watering. Then the hydrological characteristics i.e. leaf water potential at dawn, the specific leaf area, stoma density, nitrogen content, and biomass were compared. And then different strategies in response to drought stresses were discussed. Drought stresses significantly decrease the leaf water potential at dawn (ψdawn) of Chloris virgata, while dew does not affect on the value of ψdawn of Chloris virgata. Drought stresses significantly lower ψdawn of Leymus chinensis at the tenth day after the drought period. Dew significantly affects the ψdawn of Leymus chinensis. Drought stresses significantly reduce Specific Leaf Area (SLA) and stomatal density; however, both of them are recovered to the normal level after re-watering. Nitrogen concentrations of Leymus chinensis are significantly increased under drought stresses; meanwhile there are no significant changes for Chloris virgata. Ratio of root and crown is improved for Leymus chinensis under drought stresses,and there is no differences for Chloris virgata. But the drought significantly improves the ratio of fruits and crown for Chloris virgata. The result indicates that more biomass is allocated into the roots for Leymus chinensis under drought stresses. This pattern is benefit for water absorption and improves resistance to the drought. By contrary, more biomass is input to produce seeds for Chloris virgata, which is helpful to expand its population. The results indicate that different strategies for two species are applied to in response to the drought stresses, and C3 species L. chinensis displays the higher ability to resist drought than that of C4 species C. virgata.

Sap Flow Dynamics of Ulmus pumila var. sabulosa in Hunshandake Sandland

WANG Jingyuan;JIANG Gaoming;LIU Meizhen
Science & Technology Review. 2011, 29 (25): 54-58. ;  doi: 10.3981/j.issn.1000-7857.2011.25.008
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Abstract ( 371 )
Sap flux density of Ulmus pumila var. sabulosa in typical elms sparse forest in Hunshandake Sandland of Inner Mongolia was studied by using Granier technology. Nine dominant trees with different Diameters at Breast Height (DBH) which belong to three classes of DBH, that is, 15—25cm (small DBH), 25—35cm (medium DBH) and >35cm (large DBH), respectively in natural forest were selected and measured in terms of sap flux density. At the same time, various environmental factors including air temperature, relative humidity, photosynthetically active radiation, and wind speed were monitored in the whole growing season. The sap flow characteristics of forest stand are: sap flow density peak value of large DBH is larger than that of medium DBH tree and then small DBH tree. Sap flow density of large DBH trees change gently because age of stand. Average monthly sap flow density is less with the shift of growing season; the sap flow density enters into the state of weakly fluctuation in the end of growing season (October). The maximum value of average monthly sap flow density for varied tree species appears from June to August, the differences among dominant, medium and small trees are large. The main influence environmental factors are VPD, PAR, Ta. At different months, the dominant environmental factors have changed, but the two main factors are PAR and VPD.

Ecological and Economic Benefit of Chicken Grazing on Hunshandake Sandland

SU Benying;;LI Yonggeng;SU Hua;XU Hong;JIANG Gaoming;
Science & Technology Review. 2011, 29 (25): 59-64. ;  doi: 10.3981/j.issn.1000-7857.2011.25.009
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Abstract ( 613 )
The feedstuff consumption of chickens grazing on the Hunshandake Sandland was investigated through a control experiment. The impacts of chicken grazing on the productivity of the grassland was also identified. The result showed that farming of chickens on the grassland could save about 26% of the total feedstuff, which meant, to produce 1kg meat the free-range chicken could save 1.48kg feedstuff comparing with cage-raising chicken. Chicken grazing on the grassland had a little effect on the productivity of grassland which is much lower than the impacts of cattle and goat grazing. Chicken farming on the grassland is not only good for restoration of the degenerating grassland vegetation, but it could improve the income of local herdsman. The data demonstrated that the profit per hectare with this mode was about 1500 Yuan RMB higher than that with traditional grazing mode. Meanwhile, the outputs of this mode, including organic chickens and eggs, could meet the increasing need for healthy food.
Articles

On-road Emission Characteristics of Gaseous Pollutants from Low-speed Vehicles

YAO Zhiliang;SHEN Xianbao;ZHANG Yingzhi;WANG Qidong
Science & Technology Review. 2011, 29 (25): 65-70. ;  doi: 10.3981/j.issn.1000-7857.2011.25.010
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Abstract ( 339 )
On-road emission tests were conducted for six low-speed vehicles using SEMTECH-DS, a Portable Emission Measurement System (PEMS). The instantaneous speed and emission concentration data of CO2, CO, NOx and HC were collected, and the relationship between the driving cycle and emission, and the emission factors are analyzed based on the testing data. The results show that the emission factors of CO2, CO, NOx and HC decrease with the increase of speed and increase with the increase of acceleration; the emission rates are the highest in the acceleration mode, followed by the cruising mode, and are the lowest in the idling mode. The emission rates of the four pollutants for low-speed vehicles have a very good correlation with VSP; the average emission factors of the CO2, CO, NOx and HC for tested low-speed vehicles are 110.1, 1.66, 1.78 and 0.49g·km-1, respectively. The CO emission factors are comparable to the regulated values of light-duty diesel trucks with Nation II technology; and NOx and HC emission factors are comparable to the regulated values of light-duty diesel trucks with Nation I technology.

Structure Analysis on the Cable of Coattails Logarithmic Antenna

SONG Zongfeng;LIANG Hanxin;CHEN Jianjun
Science & Technology Review. 2011, 29 (25): 71-74. ;  doi: 10.3981/j.issn.1000-7857.2011.25.011
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Abstract ( 349 )
In order to make antenna have a beautiful feature and a reliable structure, with coattails logarithmic antenna structure is used as the research object, an approximate method for calculating the structure size of logarithmic antenna is proposed. The requirement for the given dipole sag is met in the following calculations. First of all, tension value of each oscillator are obtained by using small sag flexible cable theory, and then by analyzing stressed conditions of antenna cable in the vertical plane, the coordinates of each hanging point and the tension of both ends for cable are calculated through the torque balance. If the tension value of each oscillator and cable is greater than the corresponding required value, then the cable is re-analyzed by adjusting the oscillator sag and the giving the shortest tail until the tension values are within the allowable range, and then the iterative calculation is ended. The length of antenna cable, tail, and cable pre-tension are obtained, thus the data give the support to antenna structure design, material selection, and engineering applications. Finally, through the verification of practical engineering project, the analysis results obtained by using the method have an important value for engineering applications. This method is applicable to the analysis and calculation of cable for vertical wire antenna acted by focus load with different size, distance, and directions.

Hopf Bifurcation Analysis on a Predator-prey System with Double Time Delays

XU Xiuyan
Science & Technology Review. 2011, 29 (25): 75-79. ;  doi: 10.3981/j.issn.1000-7857.2011.25.012
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Abstract ( 328 )
A kind of predator-prey system with double time delays i.e. the hunting delay (the time delay of the predator maturation) τ1 and the growth time delay of the predator and the prey τ2 is investigated. Stability analysis on the equilibrium point of the system is carried out, and the ranges of the time delays are determined. Thus, the impact of the predator and the prey is in-depth studied. First of all, the hunting delay (the time delay of the predator maturation) τ1 and the growth time delay of the predator and the prey τ2 are taken as parameters, respectively. The range of the roots with a strictly negative real part is found by analyzing the distribution of characteristic roots for the linearized equation. The condition to ensure the stability of the zero solution of the system and its stable domain are decided. Secondly, when the hunting delay τ1 is in the stable region, the stability and the existence of Hopf bifurcation are given. Then the Hopf bifurcation is discussed by using the center manifold theory and normal form method introduced by Hassard and Kazarinoff. Both direction and stability of the Hopf bifurcation are considered, and the ranges for the system parameters are obtained.
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Science & Technology Review. 2011, 29 (25): 80-80. ;  doi:
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