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Study of a model for correcting the effects of horizontal advection on surface fluxes measurement based on remote sensing

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Science China Earth Sciences 2006年第S2期49卷 273-280页

作者： TIAN Jing, ZHANG Renhua, SUN Xiaomin, ZHU Zhilin & ZHOU Yanlian key laboratory of {2. network observation and modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Graduate University of the Chinese Academy of Sciences, Beijing 100049, China 1. Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China 2. Graduate University of the Chinese Academy of Sciences Beijing 100049 China

As well known, the methods of remote sensing and Bowen Ratio for retrieving surface flux are based on energy balance closure; however, in most cases, surface energy observed in experiment is lack of closure. There are two main causes for this: one is from the errors of the observation devices and the differences of their observational scale; the other lies in the effect of horizontal advection on the surface flux measurement. Therefore, it is very important to estimate the effects of horizontal advection quantitatively. Based on the local advection theory and the surface experiment, a model has been proposed for correcting the effect of horizontal advection on surface flux measurement, in which the relationship between the fetch of the measurement and pixel size for remote sensed data was considered. By means of numerical simulations, the sensitivities of the main parameters in the model and the scaling problems of horizontal advection were analyzed. At last, by using the observational data acquired in agricultural field with relatively homogeneous surface, the model was validated.

关键词： fetch horizontal advection energy balance pixel size ChinaFLUX.

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A preliminary study for spatial representiveness of flux observation at ChinaFLUX sites

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Science China Earth Sciences 2006年第S2期49卷 24-35页

作者： Ml Na, YU Guirui, WANG Panxing, WEN Xuefa & SUN Xiaomin Nanjing University of Information Science and Technology, Nanjing 2.0044, China key laboratory of {2. network observation and modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 1. Nanjing University of Information Science and Technology Nanjing 210044 China 2. Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

The results of eddy covariance observation system could represent the physical process at certain area of the surface. Thus point-to-area representativeness was of primary interest in flux observation. This research presents a preliminary study for flux observation at ChinaFLUX sites by the use of observation data and Flux Source Area Model (FSAM). Results show that the footprint expands and is further away from flux tower when atmosphere becomes more stable, the observation height increases, or the surfaces become smoother. This suggests that the area represented by the flux observation becomes larger. The distances from the reference point to the maximum point Smax and the minimum point x1 of source weight function (Dmax and Dmin, respectively) can be influenced by atmosphere stability which becomes longer when atmosphere is more stable. For more rough surfaces and lower observation point Dmax and Dmin become shorter. This research gives the footprint at level P=90% at ChinaFLUX sites at different atmosphere stability. The preliminary results of spatial representiveness at ChinaFLUX sites were given based on the dominant wind direction and footprint response to various factors. The study also provides some theoretical basis for data quality control and evaluating data uncertainty.

关键词： eddy covariance method footprint source weight function ChinaFLUX.

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Surface roughness length dynamic over several different surfaces and its effects on modeling fluxes

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Science China Earth Sciences 2006年第S2期49卷 262-272页

作者： ZHOU Yanlian, SUN Xiaomin, ZHU Zhilin, ZHANG Renhua, TIAN Jing, LIU Yunfen, GUAN Dexin & YUAN Guofu key laboratory of {2. network observation and modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Graduate University of the Chinese Academy of Sciences, Beijing 100049, China Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China 1. Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China2. Graduate University of the Chinese Academy of Sciences Beijing 100049 China3. Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China

Roughness length and zero-plane displacement over three typical surfaces were calculated iteratively by least-square method, which are Yucheng Experimental Station for agriculture surfaces, Qianyanzhou Experimental Station for complex and undulant surfaces, and Changbai Mountains Experimental Station for forest surfaces. On the basis of roughness length dynamic, the effects of roughness length dynamic on fluxes were analyzed with SEBS model. The results indicate that, aerodynamic roughness length changes with vegetation conditions (such as vegetation height, LAI), wind speed, friction velocity and some other factors. In Yucheng and Changbai Mountains Experimental Station, aerodynamic roughness length over the fetch of flux tower changes with vegetation height and LAI obviously, that is, with the increase of LAI, roughness length increases to the peak value firstly, and then decreases. In Qianyanzhou Experimental Station, LAI changes slightly, so the relationship between roughness length and LAI is not obvious. The aerodynamic roughness length of Yucheng and Changbai Mountains Experimental Station changes slightly with wind direction, while aerodynamic roughness length of Qianyanzhou Experimental Station changes obviously with wind direction. The reason for that is the terrain in Yucheng and Changbai Mountains Experimental Station is relatively flat, while in Qianyanzhou Experimental Station the terrain is very undulant and heterogeneous. With the increase of wind speed, aerodynamic roughness length of Yucheng Experimental Station changes slightly, while it decreases obviously in Qianyanzhou Experimental Station and Changbai Mountains Experimental Station. Roughness length dynamic takes great effects on fluxes calculation, and the effects are analyzed by SEBS model. By comparing 1 day averaged roughness length in Yucheng Experimental Station and 5 day averaged roughness length of Qianyanzhou and Changbai Mountains Experimental Station with roughness length parameter

关键词： ChinaFLUX surface roughness length dynamic spatial heterogeneity Yucheng Experimental Station Qianyanzhou Experimental Station Changbai Mountains Experimental Station.

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The spatial pattern of grassland aboveground biomass on Xizang Plateau and its climatic controls

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Journal of Plant Ecology 2015年第1期8卷 30-40页

作者： Yanbin Jiang Jian Tao Yongqi Huang Juntao Zhu Li Tian Yangjian Zhang Lhasa Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences11A Datun RoadChaoyang DistrictBeijing 100101China Hubei Key Laboratory of Economic Forest Germplasm Improvement and Resources Comprehensive Utilization Huanggang Normal UniversityNo.146Xingang 2nd RoadDeveloping DistrictHuanggang 438000China

Aims Grassland is the most widely distributed vegetation type on the Xizang *** remote sensing estimation of the grass-land aboveground biomass(AGB)in this region is influenced by the types of vegetation indexes(VIs)used,the grain size(resolution)of the remote sensing data and the targeted ecosystem *** study attempts to answer the following questions:(i)Which VI can most accurately reflect the grassland AGB distribution on the Xizang Plateau?(ii)How does the grain size of remote sensing imagery affect AGB reflection?(iii)What is the spatial distribution pattern of the grassland AGB on the plateau and its relationship with the climate?Methods We investigated 90 sample sites and measured site-specific AGBs using the harvest method for three grassland types(alpine meadow,alpine steppe and desert steppe).For each sample site,four VIs,namely,Normalized Difference VI(NDVI),Enhanced VI,Normalized Difference Water Index(NDWI)and Modified Soil-Adjusted VI(MSAVI)were extracted from the Moderate Resolution Imaging Spectroradiometer(MODIS)products with grain sizes of 2.0 m and 1 *** regression models were employed to iden-tify the best estimator of the AGB for the entire grassland and the three individual grassland *** Wilcoxon tests were applied to assess the grain size effect on the AGB *** linear models were used to quantify the relationships between the spatial distribution of the grassland AGB and climatic *** Findings The results showed that the best estimator for the entire grass-land AGB on the Xizang Plateau was MSAVI at a 2.0 m grain size(MSAVI_(2.0 m)).For each individual grassland type,the best estimator was MSAVI at a grain size of 2.0 m for alpine meadow,NDWI at a grain size of 1 km for alpine steppe and NDVI at a grain size of 1 km for desert *** explanation ability of each VI for the grassland AGB did not significantly differ for the two grain *** on the best fit model(AGB=−10.80+

关键词： aboveground biomass grassland vegetation index Xizang Plateau grain size precipitation

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Impacts of climate change and grazing intensity on soil organic carbon in alpine meadow

Impacts of climate change and grazing intensity on soil orga...

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International Conference on Business Management and Electronic Information (BMEI)

作者： Li, Xiaojia Zhang, Xianzhou Jiang, Hongtao Ma, Qinglong Shen, Zhenxi Fan, Yuzhi Yan, Wei Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Graduate University Chinese Academy of Science Beijing China School of Geography Beijing Normal University Beijing China NO.2 Middle School of Xilingol League Xilinhot Inner Mongolia China

ISBN: (纸本)9781612841069

In this paper, soil organic carbon was simulated in the next 50 years with CENTURY model in different climate scenarios at Damxung alpine meadow ecosystem. The result shows that temperature and precipitation are the main contributor to the changes of soil organic carbon. Increase in temperature and precipitation can reduce the accumulation of soil organic carbon resulting in the release of soil carbon. Simulation results are consistent in three climate change scenarios (temperature and precipitation increasing, temperature increasing and precipitation unchangeable, temperature unchangeable and precipitation increasing). The content of soil organic carbon decreased, only slightly difference in extent in the three scenarios. Grazing intensity was also a main factor to affect soil organic carbon and the influence on soil organic fractions was different. © 2.11 IEEE.

关键词： Climate change

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Quantitative estimation of the shrub canopy LAI from atmosphere-corrected HJ-1 CCD data in Mu Us Sandland

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Science China Earth Sciences 2010年第S1期53卷 26-33页

The leaf area index(LAI) is an important ecological parameter that characterizes the interface between vegetation canopy and the *** addition,it is used by most process-oriented ecosystem *** paper investigates the potential of HJ-1 CCD data combined with linear spectral unmixing and an inverted geometric-optical model for the retrieval of the shrub LAI in Wushen Banner of Inner Mongolia in the Mu Us ***(Moderate Resolution Atmospheric Radiance and Transmittance Model) was used for atmospheric *** was extracted using the threshold of the normalized difference vegetation index,with which water bodies and farmland were separated,in combination with a vegetation map of the People's Republic of China(1:1000000).Using the geometric-optical model,we derive the per-pixel reflectance as a simple linear combination of two components,namely sunlit background and *** fraction of sunlit background is related to the shrub *** the support of HJ-1 CCD data,we employ linear spectral unmixing to obtain the fraction of sunlit background in an atmospherically corrected HJ *** addition,we use the measured shrub canopy structural parameters for shrub communities to invert the geometric-optical model and retrieve the pixel-based shrub *** total,18 sample plots collected in Wushen Banner of Inner Mongolia are used for *** results of the shrub LAI show good agreement with R2.of 0.817 and a root-mean-squared error of 0.173.

关键词： shrub leaf area index inversion HJ-1 data geometric-optical model MODTRAN Mu Us Sandland

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Nitrogen use efciency of terrestrial plants in China: geographic patterns, evolution, and determinants

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Ecological Processes 2021年第1期10卷 967-979页

作者： Jiaqiang Liao Zhaolei Li Jinsong Wang Dashuan Tian Di Tian Shuli Niu Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China. College of Resources and Environment University of Chinese Academy of SciencesBeijingChina. Research Center of Forest Management Engineering of State Forestry and Grassland Administration College of ForestryBeijing Forestry UniversityBeijingChina. Institute of Agricultural Sciences Department of Environmental Systems ScienceETHUniversitätsstrasse 28092 ZürichSwitzerland. Swiss Federal Institute for Forest Snow and Landscape Research WSLZürcherstrasse 1118903 BirmensdorfSwitzerland.

Background:Plant nitrogen use efciency(NUE)is an important ecological indicator that refects the capacity of a plant to transform nitrogen into production,which is essential for further elucidating plant growth and terrestrial ecosystem *** there are a growing number of studies that address NUE changes at local scales,the variations of NUE over large spatial scales remain *** this study,we analyzed the geographic patterns of NUE and explored its phylogenic and environmental drivers across 1452.species at 1102.sites in ***:NUE tended to decrease with latitude(r=−0.56),whereas it increased with longitude(r=0.54),and varied widely in diferent ecosystems and plant life ***,NUE was negatively correlated with plant foliar phosphorus concentration(r=−0.53),soil pH(r=−0.10),soil total phosphorus(r=−0.13)and available phosphorus(r=−0.05),but positively with the mean annual temperature(r=0.32.,annual precipitation(r=0.2.),and aridity index(r=0.2.).NUE was signifcantly altered with phylogeny and evolved toward a lower value(r=−0.2.),which may have been due to increasing nitrogen deposition and fxation in biogeochemical ***,the combination of foliar phosphorus concentration,phylogeny,climate,and soil properties accounted for 52.7%of the total variations of *** particular,foliar phosphorus concentration was the most important factor,whereas plant evolutionary history was second in contributing to NUE ***:Our study emphasizes the pivotal role of plant stoichiometry and phylogeny in nitrogen cycling and suggests incorporating them into earth system models to better understanding plant growth and nitrogen cycling in the context of environmental changes.

关键词： Nitrogen use efciency Foliar phosphorus Geographic pattern Stoichiometry Plant phylogeny Climate Soil properties

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Relationship of minimum winter temperature and temperature seasonality to the northern range limit and species richness of trees in North America

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Journal of Geographical Sciences 2022年第2期32卷 280-290页

作者： Hong QIAN ZHANG Yangjian Robert E.RICKLEFS Xianli WANG Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China Department of Biology University of Missouri–St.LouisSt.LouisMO 63121USA Northern Forestry Centre Canadian Forest ServiceNatural Resources Canada5320-122nd StreetEdmontonAB T6H 3S5Canada Department of Renewable Resources University of Alberta751 General Service Building EdmontonAB T6G 2H1Canada

Biologists have considered both winter coldness and temperature seasonality as major determinants of the northern limits of plants and animals in the Northern Hemisphere,which in turn drive the well-known latitudinal diversity ***,few studies have tested which of the two climate variables is the primary *** this study,we assess whether winter coldness or temperature seasonality is more strongly associated with the northern latitudinal limits of tree species and with tree species richness in North *** species were recorded in each of 1198 quadrats of 110 km×110 km in North *** used correlation and regression analyses to assess the relationship of the latitude of the northern boundary of each species,and of species richness per quadrat,with winter coldness and temperature *** richness was analyzed within 38 longitudinal,i.e.,north-south,bands(each being>1100 km long and 110 km wide).The latitudes of the northern range limits of tree species were three times better correlated with minimum temperatures at those latitudes than with temperature *** average,minimum temperature and temperature seasonality together explained 81.5%of the variation in the northern range limits of the tree species examined,and minimum temperature uniquely explained six-fold(33.7%versus 5.8%)more of this variation than did temperature *** of tree species richness with minimum temperatures were stronger than correlations with temperature seasonality for most of the longitudinal bands *** to temperature seasonality,winter coldness is more strongly associated with species distributions at high latitudes,and is likely a more important driver of the latitudinal diversity gradient.

关键词： cold tolerance latitudinal diversity gradient minimum temperature temperature seasonality temperature variation trees tropical conservatism hypothesis

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Linking leaf elemental traits to biomass across forest biomes in the Himalayas

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Science China Earth Sciences 2024年第5期67卷 1518-1528页

作者： Nita DYOLA Eryuan LIANG Josep PEÑUELAS J.Julio CAMARERO Shalik Ram SIGDEL Sugam ARYAL Wentao LIN Xiang LIU Yongwen LIU Xingliang XU Sergio ROSSI State Key Laboratory of Tibetan Plateau Earth System Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Laboratoire sur lesécosystèmes terrestres boréaux Département des Sciences FondamentalesUniversitédu QuébecàChicoutimi555Boulevard de l′UniversitéChicoutimi(QC)G7H2B1Canada CSIC Global Ecology Unit CREAF-CSIC-UABBellaterraE-08193 CataloniaSpain CREAF Cerdanyola del VallèsE-08193 CataloniaSpain Instituto Pirenaico de Ecología(IPE-CSIC) Avenida Montañana 1005Zaragoza 50059Spain Friedrich-Alexander-Universität Erlangen-Nürnberg Institut für GeographieErlangen 91058Germany State Key Laboratory of Grassland Agro-Ecosystems College of EcologyLanzhou UniversityLanzhou 730000China Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China

Plants require a number of essential elements in different proportions for ensuring their growth and *** elemental concentrations in leaves reflect the functions and adaptations of plants under specific environmental ***,less is known about how the spectrum of leaf elements associated with resource acquisition,photosynthesis and growth regulates forest biomass along broad elevational *** examined the influence of leaf element distribution and diversity on forest biomass by analyzing ten elements(C,N,P,K,Ca,Mg,Zn,Fe,Cu,and Mn)in tree communities situated every 100 meters along an extensive elevation gradient,ranging from the tropical forest(80 meters above sea level)to the alpine treeline(42.0 meters above sea level)in the Kangchenjunga Landscape in eastern Nepal *** calculated communityweighted averages(reflecting dominant traits governing biomass,i.e.,mass-ratio effect)and functional divergence(reflecting increased trait variety,i.e.,complementarity effect)for leaf elements in a total of 1,859 trees representing 116 *** increasing mass-ratio effect and decreasing complementarity in leaf elements enhance forest biomass accumulation.A combination of elements together with elevation explains biomass(52.2.of the variance)better than individual elemental trait diversity(0.05%to 2.%of the variance).Elevation modulates trait diversity among plant species in biomass *** promotes biomass at lower elevations,but reduces biomass at higher elevations,demonstrating an interaction between elevation and *** interaction between elevation and mass-ratio effect produces heterogeneous effects on biomass along the elevation *** research indicates that biomass accumulation can be disproportionately affected by elevation due to interactions among trait diversities across vegetation *** higher trait variation enhances the adaptation of species to environmental changes,it reduces

关键词： ecosystem function Elevational gradient Functional diversity Functional traits Leaf elements Niche complementarity

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Hydrogeomorphic ecosystem Responses to Natural and Anthropogenic Changes in the Loess Plateau of China

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Earth and Planetary Sciences 1000年第1期45卷 223-243页

作者： Bojie Fu Shuai Wang Yu Liu Jianbo Liu Wei Liang Chiyuan Miao 1State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China email: bfu@*** 2State Key Laboratory of Earth Surface Processes and Resource Ecology Faculty of Geographical Science Beijing Normal University Beijing 100875 China 3Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China 4University of Chinese Academy of Sciences Beijing 100049 China

China's Loess Plateau is both the largest and deepest loess deposit in the world, and it has long been one of the most severely eroded areas on Earth. Since the 1970s, numerous soil- and water-conservation practices have been implemented: terracing, planting of vegetation, natural vegetation rehabilitation, and check-dam construction. With the implementation of the Grain-for-Green Project in 1999, the Loess Plateau has become the most successful ecological restoration zone in China. However, these large-scale restoration measures and drought have significantly reduced both runoff and sediment from the Loess Plateau. This situation has both advantages and disadvantages for the lower Yellow River. Some local soil erosion has been successfully controlled, but the whole regional ecosystem remains very fragile. Therefore, it is necessary to balance each ecosystem service, for example, by determining the region's vegetation capacity and its spatial distribution for the sustainable development of the socioecological system of the Loess Plateau.

关键词： soil erosion ecological restoration sediment reduction soil desiccation climate change

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