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Species-area relationship within and across functional groups at alpine grasslands on the northern Tibetan Plateau,China

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Journal of Mountain Science 2016年第2期13卷 265-275页

作者： zhou Nan WU Jian-shuang SHEN Zhen-xi zhang xian-zhou YANG Peng-wan Lhasa National Ecological Research Station Key Laboratory of Ecosystem Network Observation and ModellingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of sciences University of Chinese Academy of Sciences Functional Biodiversity Dahlem Centre of Plant SciencesFree University of Berlin

The species-area relationship （SAR） is one of the most fundamental concepts in community ecology and is helpful for biodiversity conservation. However, few studies have systematically addressed this topic for different alpine grassland types on the Tibetan Plateau, China. We explored whether the plant composition of different functional groups affects the manner in which species richness inereases with increasing area at scales ≤ 1.0 m^2. We also compared species richness （S） within and across forbs, legumes, sedges and grasses, with sampling subplot area （A） increasing from 0.0625 m^2 to 1.0 m^2 between alpine meadow and steppe communities. We applied a logarithmic function （S = b0 ＋ b1 ln A） to determine the slope and intercept of SAR curves within and across functional groups. The results showed that the logarithmic relationship holds true between species richness and sampling area at these small scales. Both the intercept and slope of the logarithmic forbs-area curves are significantly higher than those for the three other functional groups （P 〈 0.05）. Forb accounts for about 91.9 % of the variation in the intercept and 75.0% of the variation in the slope of the SAR curve when all functional groups＇ data were pooled together. Our results indicated that the different SAR patterns should be linked with species dispersal capabilities, environmental filtering, and life form composition within alpine grassland communities. Further studies on the relationship between species diversity and ecosystem functions should specify the differential responses of different functional groups to variations in climate and anthropogenic disturbances.

关键词： Changtang Nature Reserve Complementary response Plant functional groups Plant life forms Species coexistence

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Biomass Allocation Patterns of Alpine Grassland Species and Functional Groups along a Precipitation Gradient on the Northern Tibetan Plateau

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Journal of Mountain Science 2013年第6期10卷 1097-1108页

作者： WU Jian-shuang SHEN Zhen-xi zhang xian-zhou SHI Pei-li Lhasa National Ecological Research Station Key Laboratory of Ecosystem Network Observation and Modelling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of sciences

Variations in the fractions of biomass allocated to functional components are widely considered as plant responses to resource availability for grassland plants. Observations indicated shoots isometrically relates to roots at the community level but allometrically at the species level in Tibetan alpine grasslands. These differences may result from the specific complementarity of functional groups between functional components, such as leaf, root, stem and reproductive organ. To test the component complementary responses to regional moisture variation, we conducted a multi-site transect survey to measure plant individual size and component biomass fractions of common species belonging to the functional groups： forbs, grasses, legumes and sedges on the Northern Tibetan Plateau in peak growing season in 2010. Along the mean annual precipitation （MAP） gradient, we sampled 7o species, in which 2o are in alpine meadows, 20 in alpine steppes, 15 in alpine desert-steppes and 15 in alpine deserts, respectively. Our results showed that the size of alpine plants is small with individual biomass mostly lower than 1.0 g. Plants keep relative conservative component individual responses moisture functional fractions across alpine grasslands at the level. However, the complementary between functional components to variations specifically differ among groups. These results indicate that functional group diversity may be an effective tool for scaling biomass allocation patterns from individual up to community level. Therefore, it is necessary andvaluable to perform intensive and systematic studies on identification and differentiation the influences of compositional changes in functional groups on ecosystem primary services and processes.

关键词： Biomass fractions Complementaryresponse Functional components Functional groups Changtang Plateau

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Relativistic Quadrupole Polarizability for the Ground State of Hydrogen-Like Ions

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Chinese Physics Letters 2012年第6期29卷 110-113页

作者： zhang Yong-Hui TANG Li-Yan zhang xian-zhou SHI Ting-Yun Jim Mitroy Department of Physics Henan Normal UniversityXinxiang 453007 State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071 School of Engineering Charles Darwin UniversityDarwin NT 0909Australia

The static quadrupole polarizabilities for hydrogen-like ions from Z =1 to Z =100 in the 1S1/2 ground state are calculated to high precision by solving the Dirac equation using the B-spline Galerkin *** results are consistent with the expression of Kaneko [***.B 10 (1977) 3347] at low *** quadrupole oscillator strength sum Σn f(2)gn is computed to be zero to a very high degree of precision.

关键词： method spline oscillator

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Response of Ecosystem Respiration to Experimental Warming and Clipping at Daily Time Scale in an Alpine Meadow of Tibet

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Journal of Mountain Science 2013年第3期10卷 455-463页

作者： FU Gang SHEN Zhen-xi zhang xian-zhou YU Cheng-qun zhou Yu-ting LI Yun-long YANG Peng-wan Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences University of Chinese Academy of Sciences

The alpine meadow, as one of the typical vegetation types on the Tibetan Plateau, is one of the most sensitive terrestrial ecosystems to climate warming. However, how climate warming affects the carbon cycling of the alpine meadow on the Tibetan Plateau is not very dear. A field experiment under controlled experimental warming and clipping conditions was conducted in an alpine meadow on the Northern Tibetan Plateau since July 2008. Open top chambers （0TCs） were used to simulate climate warming. The main objective of this study was to examine the responses of ecosystem respiration （Reco） and its temperature sensitivity to experimental warming and clipping at daily time scale. Therefore, we measured Reco once or twice a month from July to September in 2010, from June to September in 2011 and from August to September in 2012. Air temperature dominated daily variation of Reco whether or not experimental warming and clipping were present. Air temperature was exponentially correlated with Reco and it could significantly explain 58-96% variation of Redo at daily time scale. Experimental warming and clipping decreased daily mean Reco by 5.8-37.7% and -11.9-23.0%, respectively, although not all these changes were significant. Experimental warming tended to decrease the temperature sensitivity of Reco, whereas clipping tended to increase the temperature sensitivity of Reco at daily time scale. Our findings suggest that Reco wasmainly controlled by air temperature and may acclimate to climate warming due to its lower temperature sensitivity under experimental warming at daily time scale.

关键词： Acclimation Air temperature Open topchamber Temperature sensitivity Respirationquotient ( Q10)

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Clipping Alters the Response of Biomass Production to Experimental Warming: A Case Study in an Alpine Meadow on the Tibetan Plateau, China

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Journal of Mountain Science 2015年第4期12卷 935-942页

作者： FU Gang SUN Wei YU Cheng-Qun zhang xian-zhou SHEN Zhen-Xi LI Yun-Long YANG Peng-Wan zhou Nan Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences

Predicting how human activity will influence the response of alpine grasslands to future warming has many *** this study, a field experiment with controlled warming and clipping was conducted in an alpine meadow at three elevations（4313 m, 4513 m and 4693 m） in Northern Tibet to test the hypothesis that clipping would alter warming effect on biomass *** top chambers（OTCs） were used to increase temperature since July,2008 and the OTCs increased air temperature by approximately 0.9o C ~ 1.8o C during the growing *** was conducted three times one year during growing season and the aboveground parts of all live plants were clipped to approximately 0.01 m in height using scissors since *** primary production（GPP） was calculated from the Moderate-Resolution Imaging Spectroradiometer GPP algorithm and aboveground plant production was estimated using the surface-measured normalized difference vegetation index in *** decreased the GPP, aboveground biomass（AGB） and aboveground net primary production（ANPP） at all three elevations when clipping was not *** contrast, warming increased AGB at all three elevations, GPP at the two lower elevations and ANPP at the two higher elevations when clipping was *** findings show that clipping reduced the negative effect of warming on GPP, AGB and ANPP, suggesting that clipping may reduce the effect of climate warming on GPP, AGB and ANPP in alpine meadows on the Tibetan Plateau, and therefore, may be a viable strategy for mitigating the effects of climate change on grazing and animal husbandry on the Tibetan Plateau.

关键词： Clipping Gross primary production Open top chamber Warming Alpine Meadow Tibetan Plateau

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Coherent Control of Molecular Orientation by a Terahertz Few-Cycle Laser Pulse

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Chinese Physics Letters 2013年第2期30卷 82-85页

作者： QIN Chao-Chao LIU Yu-Zhu zhang xian-zhou LIU Yu-Fang Department of Physics Henan Normal UniversityXinxiang 453007 College of Physics and Opto-electronics Engineering Nanjing University of Information Science&TechnologyNanjing 210044

The coherent control of molecular orientation by a terahertz few-cycle laser pulse is theoretically *** is demonstrated that the field-free molecular orientation results from the interference contributions between the odd and even rotational wave packet,and therefore the constructive and destructive interferences lead to the observation of the positive and negative orientations,corresponding to the positive and negative ***,the enhancement or suppression of the molecular orientation can be coherently manipulated by precisely controlling the carrier-envelope phase of the terahertz few-cycle pulse.

关键词： coherent Pulse Molecular

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Coherent Control of Molecular Alignment and Orientation by a Femtosecond Two-Color Laser Pulse

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Chinese Physics Letters 2013年第2期30卷 86-89页

作者： QIN Chao-Chao ZHAO Xing-Dong zhang xian-zhou LIU Yu-Fang Department of Physics Henan Normal UniversityXinxiang 453007

The coherent control of molecular alignment and orientation by a femtosecond two-color laser pulse is studied *** effect of the carrier-envelope phase of the femtosecond two-color laser pulse on molecular alignment and orientation is discussed,and it is shown that the enhancement or suppression of the molecular orientation can be coherently manipulated by precisely controlling the carrier-envelope phase of the femtosecond two-color laser *** addition,the time-dependent angular distributions of the molecular axis are presented.

关键词： Femto coherent alignment

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Calculation of Multiphoton Transition in Li Atoms via Chirped Microwave Pulse

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Chinese Physics Letters 2011年第10期28卷 70-73页

作者： JIA Guang-Rui zhang xian-zhou LIU Yu-Fang YU Kun ZHAO Yue-Jin College of Physics and Information Engineering Henan Normal UniversityXinxiang 453007 School of Optoelectronics Beijing Institute of TechnologyBeijing 100081

The position and width of avoided crossings of Li atom energy levels in a static electric field is presented by using the B-spline basis set method combined with the model *** the time-dependent multilevel approach,the population of Li atoms is transferred to the target state completely by one-photon,two-photon or a single multiphoton adiabatic rapid passage,which requires only a small frequency *** calculation results agree well with the experiment and novel explanations are given to understand the experimental results.

关键词： potential photon Transition

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The Dynamics of Rubidium Atoms in THz Laser Fields

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Chinese Physics Letters 2013年第7期30卷 56-59页

作者： JIA Guang-Rui ZHAO Yue-Jin zhang xian-zhou LIU Yu-Fang YU Kun School of Optoelectronics Beijing Institute of TechnologyBeijing 100081 College of Physics and Information Engineering Henan Normal UniversityXinxiang 453007

By using B-spline basis set combined with model potential,energy levels and wave functions of rubidium atoms are *** a time-dependent multi-level approach,we study the dependence of the population of rubidium atoms excited from a low lying state to a target state on the parameters of a single or two broadband terahertz laser *** population redistribution between the states n=23 and n=24 due to the interaction with terahertz pulses is analyzed in *** oscillation in the initial and final states as a function of the time delay between two half cycle pulses is shown,and the oscillation period is the same as the Kepler period of the selected *** calculation results agree well with the experiment and can be explained by the semiclassical picture.

关键词： oscillation delay state

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Population Evolution of Rydberg Rubidium Atoms by Half-Cycle Pulses

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Chinese Physics Letters 2012年第11期29卷 47-51页

Using the B-spline basis set method combined with model potential,the Stark energy level of rubidium atoms in the vicinity of n=30 is *** using a using time-dependent multilevel approach,we calculate the population redistribution of high Rydberg rubidium atoms under the interaction of external time-dependent half-cycle *** numerical results show that the population of rubidium atoms can be driven to lower or higher n levels with a train of half cycle pulses,the final population distribution of all the l states for the same n is observed after these interactions.

关键词： Rydberg spline cycle

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