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Spatial variation of net radiation and its contribution to energy balance closures in grassland ecosystems

Ecological Processes 2014年第1期3卷 190-200页

作者： Changliang Shao linghao li Gang Dong Jiquan Chen Department of Environmental Sciences University of ToledoToledoOH 43606USA Key Laboratory of Vegetation and Environmental Change Institute of BotanyThe Chinese Academy of SciencesBeijing 100093China School of life Science Shanxi UniversityTaiyuan 030006China

Introduction:Low energy balance closure(EBC)at a particular eddy-covariance flux site has increased the uncertainties of carbon,water,and energy measurements and has thus hampered the urgent research of scaling up and modeling analyses through site combinations in regional or global flux ***:A series of manipulative experiments were conducted in this study to explore the role of net radiation(Rn)in the EBC in relation to spatial variability of vegetation characteristics,source area,and sensor type in three sites of the Inner Mongolian grassland of northern ***:At all three sites,the residual fluxes of EBC peaked consistently at 110 W m^(-2).The spatial variability in net radiation was 19 W m^(-2)(5%of R_(n))during the day and 7 W m^(-2)(16%)at night,with an average of 13 W m^(-2)(11%)from eight plot measurements across the three *** area measurements of Rn significantly increased by 9 W m^(-2)during the day and decreased by 4 W m^(-2)at night in the unclipped *** radiation decreased by 25 W m^(-2)(6%of Rn)at midday and 81 MJ m^(-2)(6%)during a growing season with heavier regular clipping than that in unclipped *** Rn was lower by 11–21 W m^(-2)(~20–40%of Rn)measured by CNR1 than by Q7.1 at night,while there was only 6 W m^(-2)(~1–2%of Rn)difference during the daytime between these two types of commonly used net ***:Overall,the inclusion of the uncertainty in available energy accounted for 65%of the~110 W m^(-2)shortfalls in the lack of ***,the unclosed energy balance at these three grassland sites remains significant,with unexplored mechanisms for future research.

关键词： Inner Mongolia Eddy-covariance Energy balance closure Net radiation Spatial variability Typical steppe

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Seasonal distribution of increased precipitation in maternal environments influences offspring performance of Potentilla tanacetifolia in a temperate steppe ecosystem

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Journal of Plant Ecology 2019年第4期12卷 742-750页

作者： Yang li Longyu Hou Bing Song Shiqiang Wan Xiaoqin Sun linghao li Xi’an Botanical Garden of Shaanxi Province Institute of Botany of Shaanxi ProvinceXi’an 710061China Shaanxi Engineering Research Centre for Conservation and Utilization of Botanical Resources Xi’an 710061China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China College of life Science Hebei UniversityBaoding 071000China State Key Laboratory of Earth Surface Processes and Resource Ecology(ESPRE) Faculty of Geographical ScienceBeijing Normal UniversityBeijing 100875China

Aims Precipitation is predicted to increase in arid and semiarid regions under climate change,with greater changes in intra-and interannual distribution in the *** a major limiting factor in these regions,changes in precipitation undoubtedly influence plant growth and ***,how the temporal shifts in pre-cipitation will impact plant populations are *** A 3-year field experiment and a greenhouse experiment were conducted in a temperate grassland in northern China to examine the impacts of seasonal(spring and summer)increased precipitation on offspring performance of a common species,Potentilla *** Findings Our results showed that the amounts and timing of increased precipitation both played important roles in regulating offspring performance of *** in the temperate steppe *** precipitation in spring at maternal stage stimulated seed production,germination percentage and seedling biomass,whereas increased precipitation in summer at maternal stage stimulated seedling *** timing of increased precipitation influenced seed attributes,whereas the amount of increased precipitation influenced offspring seedling *** results indicate that population development of *** may be underestimated under future increased precipitation regime,if the transgenerational effect is not taken into account.

关键词： precipitation regime seed traits seedling growth semiarid grassland

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Natural^(15)N abundance in soils and plants in relation to N cycling in a rangeland in Inner Mongolia

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Journal of Plant Ecology 2010年第3期3卷 201-207页

作者： Yuqing Xu Jicheng He Weixin Cheng Xuerong Xing linghao li National Climate Center China Meteorological Administration46 South Zhongguancun Avenue HaidianBeijing 100081China State Key Laboratory of Vegetation and Environmental Change Institute of Botanythe Chinese Academy of Sciences20 NanxincunXiangshanBeijing 100093China Energy Saving Environmental Protection and Occupational Safety and Health Research InstituteChina Academy of Railway Sciences2 DaliushuluBeijing 100081China Department of Environmental Studies University of California1156 High StreetSanta CruzCA 95064USA

Aims Natural 15N abundance provides integrated information about nitrogen(N)input,transformation and output,indirectly reflecting N cycling traits within terrestrial ***,relationships between natural 15N abundance and N cycling processes are poorly understood in ***,our primary objectives were to(i)examine the effects of grazing at varying levels of intensity on d15N of soils and plants in a semi-arid grassland;(ii)detect the relationships between d15N of soils and four major N cycling processes(***,nitrification,denitrification and ammonia volatilization);and(iii)determine whether d15N of soils can be used as an indicator of N cycling in this semi-arid *** The field experiment was conducted within the long-term(17-year)grazing enclosures in a semi-arid grassland in Inner *** grazing intensities(0.00,1.33,2.67,4.00 and 5.33 sheep ha1)were designed.d15N values of topsoils(0–10 cm),surface soils(0–2 cm)and plants were measured in *** in d15N of soils and plants between the five grazing intensities were *** of four soil N cycling processes were measured periodically during the 2005 and 2006 growing *** d15N values of topsoils were linked to the four N cycling processes to investigate their *** Findings The d15N values of topsoils(5.20–5.96&)were substantially higher than the d15N values of plants(2.51–2.93&)and surface soils(1.44–2.92&)regardless of grazing *** 15N-depleted N losses during microbial decomposition of organic matter in concert with the downward movement of residual substrate over time are the possible causes of higher d15N values in topsoils than in surface *** addition,the d15N values of topsoils were positively correlated with the d15N values of both plants and surface ***,especially the high-intensity grazing(5.33 sheep ha1),resulted in a significant decrease in d15N of surface ***,no statistically sig

关键词： d15N NH3 volatilization mineralization nitrification denitrification grazing intensity grassland

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Tomographic SAR imaging with large elevation aperture: a P-band small UAV demonstration

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Science China(Information Sciences) 2022年第3期65卷 211-224页

作者： Tao ZENG Minkun liU Yan WANG Zegang DING linghao li Zhen WANG Yangkai WEI Jianping WANG Radar Research Lab School of Information and Electronics Beijing Institute of Technology Beijing Institute of Technology Chongqing Innovation Center Yangtze Delta Region Academy of Beijing Institute of Technology Faculty of Electrical Engineering Mathematics and Computer Science (EEMCS) Delft University of Technology

Elevation resolution is an important indicator in tomographic SAR imaging as it represents the ability to discriminate closed targets in elevation. In general, the elevation resolution is proportional to the length of the elevation aperture. However, as the elevation aperture increases, the geometric consistency of the image will undesirably deteriorate and hence fails the image coregistration approach required by the traditional super-resolution tomographic imaging. In this paper, a new super-resolution tomographic imaging method is proposed to overcome the inconsistency problem caused by the large elevation aperture. The core strategy is to get rid of two-dimensional image coregistration by applying a three-dimensional(3 D) back projection like imaging manner: the 3 D space is firstly divided into a 3 D imaging grid, each of which is individually imaged via compressive sensing for super-resolution. The effectiveness of the proposed approach is evaluated by both computer simulations and real P-band UAV SAR data.

关键词： UAV SAR tomography large elevation aperture super-resolution P-band

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Responses of gross primary productivity to different sizes of precipitation events in a temperate grassland ecosystem in Inner Mongolia, China

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Journal of Arid Land 2016年第1期8卷 36-46页

作者： GUO Qun li Shenggong HU Zhongmin ZHAO Wei YU Guirui SUN Xiaomin li linghao liANG Naishen BAI Wenming Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Global Carbon Cycle Research Section Center for Global Environmental Research National Institute for Environmental Studies

Changes in the sizes of precipitation events in the context of global climate change may have profound impacts on ecosystem productivity in arid and semiarid grasslands. However, we still have little knowledge about to what extent grassland productivity will respond to an individual precipitation event. In this study, we quantified the duration, the maximum, and the time-integrated amount of the response of daily gross primary productivity (GPP) to an individual precipitation event and their variations with different sizes of precipitation events in a typical temperate steppe in Inner Mongolia, China. Results showed that the duration of GPP-response (τR) and the maximum absolute GPP-response (GPPmax) increased linearly with the sizes of precipitation events (Pes), driving a corresponding increase in time-integrated amount of the GPP-response (GPPtotal) because variations of GPPtotal were largely explained by τR and GPPmax. The relative contributions of these two parameters to GPPtotal were strongly Pes-dependent. The GPPmax contributed more to the variations of GPPtotal when Pes was relatively small (R was the main driver to the variations of GPPtotal when Pes was relatively large. In addition, a threshold size of at least 5 mm of precipitation was required to induce a GPP-response for the temperate steppe in this study. Our work has important implications for the modeling community to obtain an advanced understanding of productivity-response of grassland ecosystems to altered precipitation regimes.

关键词： precipitation event grassland gross primary productivity global climate change precipitation regime

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多级结构钛硅分子筛及其催化氧化应用研究进展

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化学反应工程与工艺 2021年第4期37卷 351-362页

作者：李令豪华子乐中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室上海200050

近年来,多级结构钛硅分子筛(TS-1)引起了越来越多的关注。本文综述了多级结构钛硅分子筛制备研究的最新进展,介绍了不同的制备方法和先进表征技术,并比较了各制备方法的优劣势,讨论了合成材料的孔结构、活性钛物种对烯烃环氧化催化反应... 详细信息

近年来,多级结构钛硅分子筛(TS-1)引起了越来越多的关注。本文综述了多级结构钛硅分子筛制备研究的最新进展,介绍了不同的制备方法和先进表征技术,并比较了各制备方法的优劣势,讨论了合成材料的孔结构、活性钛物种对烯烃环氧化催化反应和燃油催化氧化脱硫性能的影响。最后,对多级结构钛硅分子筛面临的挑战和未来的发展前景进行了展望。

关键词：钛硅分子筛多级孔结构活性钛烯烃环氧化燃油氧化脱硫

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煤层气井液面的光纤测量技术

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光学技术 2015年第5期41卷 442-444页

作者：黎凌浩江毅刘曰武北京理工大学光电学院北京100081 中国科学院力学研究所北京100190

分析了煤层气井液面在测量中使用的传统方法可能遇到的问题,提出了光纤非本征型珐珀干涉仪(EFPI)用于测量煤层气井液面的发展方向。针对煤层气井设计了光纤EFPI传感系统,并模拟煤层气井液面给出测量方案,准确地测出液面位置,解决了煤层... 详细信息

分析了煤层气井液面在测量中使用的传统方法可能遇到的问题,提出了光纤非本征型珐珀干涉仪(EFPI)用于测量煤层气井液面的发展方向。针对煤层气井设计了光纤EFPI传感系统,并模拟煤层气井液面给出测量方案,准确地测出液面位置,解决了煤层气井液面的测量难题,测量系统中传感器光学腔长变化的相对误差为1.48%,测量精度1μm,相比传统的电学测量方法,更加安全有效。

关键词：光学测量煤层气井液面 EFPI

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氮磷添加对菊叶委陵菜生殖特征的影响

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分子植物育种 2016年第4期14卷 1027-1030页

作者：李阳李倩李凌浩陕西省西安植物园陕西省植物研究所西安710061 中国科学院植物研究所北京100093

氮和磷是植物生长所必须的营养元素之一,影响到植物的生长、发育和繁殖等过程。本研究通过野外实验和室内试验,分析氮磷添加对菊叶委陵菜生殖特征的影响。其结果显示:氮磷添加显著影响菊叶委陵菜的生殖生物量、种子产量、千粒重和发芽... 详细信息

氮和磷是植物生长所必须的营养元素之一,影响到植物的生长、发育和繁殖等过程。本研究通过野外实验和室内试验,分析氮磷添加对菊叶委陵菜生殖特征的影响。其结果显示:氮磷添加显著影响菊叶委陵菜的生殖生物量、种子产量、千粒重和发芽率。种子千粒重与种子发芽率呈现正相关关系。氮和磷添加通过改变生殖构件生物量来影响其种子特征的。在草原生态系统中,氮磷是影响菊叶委陵菜繁殖的限制性因子之一。

关键词：菊叶委陵菜施肥种子

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放牧压力下高寒草甸夏秋草场潜在生产力的研究

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清华大学学报（自然科学版） 1998年第2期38卷 91-94页

作者：黄大明李凌浩清华大学生物科学与技术系中国科学院植物研究所

采用最优控制理论研究矮嵩草草甸能量动态分室模型的潜在生产力，通过放牧强度随时间的最优变化，使作为目标函数的累积采食量最大。结果指出：夏秋的高寒草甸在常放牧压力下，采食地上生活部分的最优放牧强度为２５．９０ｋＪ／（ｍ２... 详细信息

采用最优控制理论研究矮嵩草草甸能量动态分室模型的潜在生产力，通过放牧强度随时间的最优变化，使作为目标函数的累积采食量最大。结果指出：夏秋的高寒草甸在常放牧压力下，采食地上生活部分的最优放牧强度为２５．９０ｋＪ／（ｍ２ｄ），其最大累积采食量为３．２６８ＭＪ／ｍ２。采食地上生物量的最优放牧强度为２５．９４ｋＪ／（ｍ２ｄ），其最大累积采食量为３．６３１ＭＪ／ｍ２。在变放牧压力下，最优放牧强度的最大累积采食量为８．７４９ＭＪ／ｍ２。是常放牧压力下的２．５倍。

关键词：矮嵩草草甸生产力放牧强度最优控制理论

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基于布里渊增益-损耗谱的高精度分布式传感器

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激光与光电子学进展 2018年第10期55卷 86-91页

作者：仲晓轩梁浩程凌浩李杰暨南大学光子技术研究院广东广州510632

提出一种基于布里渊增益和损耗相互作用的光时域分析系统,该系统将连续光与反向的斯托克斯和反斯托克斯脉冲同时输入光纤,通过声光相互作用在布里渊增益谱中心频率处产生一个窄线宽的吸收峰。该吸收峰的线宽约为布里渊增益谱宽的1/5,并... 详细信息

提出一种基于布里渊增益和损耗相互作用的光时域分析系统,该系统将连续光与反向的斯托克斯和反斯托克斯脉冲同时输入光纤,通过声光相互作用在布里渊增益谱中心频率处产生一个窄线宽的吸收峰。该吸收峰的线宽约为布里渊增益谱宽的1/5,并且其频率与布里渊频移相关。因此利用该窄线宽吸收峰可以提高布里渊传感器的频率分辨率,从而实现高精度的温度和应变测量。实验结果表明,与传统的基于布里渊增益谱的传感器相比,该方案的温度测量精度提高了1倍多。

关键词：光纤光学布里渊散射温度和应变传感光纤传感

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