检索结果-南通市图书馆

Eddy flux corrections for CO_2.exchange in broad-leaved Korean pine mixed forest of Changbai Mountains

Science china Earth {1. 2005年第Z1期48卷 106-115页

作者： WU Jiabing, GUAN Dexin, SUN Xiaomin, YU Guirui, zhao Xiaosong, HAN Shijie & JIN Changjie institute of Applied Ecology,{2., Shenyang 110016, china Graduate school of the{2., beijing 100093, china institute of geographic sciences and natural resources {12.,{2., beijing 100101, china institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China Graduate school of the chinese academy of sciences Beijing 100093 China institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China institute of {1. {2. and natural resources research Chinese Academy of Sciences Beijing 100101 China

Based on analysis of mechanisms causing energy no-closure and nocturnal low fluxes issues for CO2.exchange studies by eddy covariance method, corrections were done with the raw data sets obtained from Changbai Mountains forest flux site, to evaluate the impacts of sonic anemometer tilt, frequency response limitations and advection on estimation of CO2.exchange, respectively. The results show that the planar fit coordinate transforming method is superior to the streamline coordinate transforming method in tilt correction. The latter could cause a systematical underestimation of eddy fluxes relating with the angle of sensor and terrain tilt. The underestimation of CO2.and energy fluxes for frequency response limitations average 3.0% and 2.0% during daytime, respectively, which increase by 9.0% and 5.5% during nighttime, respectively. The corrections of frequency response limitations are closely related to atmospheric stability. The advection loss of CO2.fluxes is dominated by nocturnal vertical advection, which is at least 1.% when the horizontal advection is neglected. It is suggested that more work be done to understand the characteristics of horizontal advection and turbulent eddies under a complexcircumstance.

关键词： eddy covariance method, carbon cycle, flux correction, CO2 exchange, tilt correction.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Seasonal variations and mechanism for environmental control of NEE of CO_2.concerning the Potentilla fruticosa in alpine shrub meadow of Qinghai-Tibet Plateau

引用

Science china Earth {1. 2006年第S2期49卷 174-185页

作者： LI Yingnian, SUN Xiaomin, zhao Xinquan, zhao Liang, XU Shixiao, GU Song, ZHANG Fawei & YU Guirui Northwest {2. of Plateau Biology, chinese academy of sciences, Xining 810001, china {2. of geographic sciences and natural resources research, chinese academy of sciences,{12., china Graduate University of chinese academy of sciences, beijing 100049, china 1. Northwest institute of Plateau Biology Chinese Academy of Sciences Xining 810001 China 2. {1. of geographic {2. and natural resources research Chinese Academy of Sciences Beijing 100101 China 3. Graduate University of chinese academy of sciences Beijing 100049 China

The study by the eddy covariance technique in the alpine shrub meadow of the Qing-hai-Tibet Plateau in 2.03 and 2.04 showed that the net ecosystem carbon dioxide exchange (NEE) exhibited noticeable diurnal and annual variations, with more distinct daily changes during the warmer seasons. The CO2.emission of the shrub ecosystem culminated in April and September while the CO2.absorption capacity reached a maximum in July and August. The absorbed carbon dioxide during the two consecutive years was 2.1.4 and 2.4.8 g CO2.m-2.respectively, yielding an average of 2.3.1.gCO2.m-2.per year: that accounts for a large proportion of absorbed CO2.in the region. Obviously, the diurnal carbon flux was negatively related to temperature, radiation and other atmospheric factors. Still, minute discrepancies in kurtosis and duration of carbon emission/absorption were detected between 2.03 and 2.04. It was found that the CO2.flux in the daytime was similarly affected by photosynthetic photon flux density in both years. Temperature appears to be the most important determinant of CO2.flux: specifically, the high temperature during the plant growing season inhibits the carbon absorption capacity. One potential explanation is that soil respiration is enhanced under such condition. Analysis of biomass revealed that the annual net carbon fixed capacity of aboveground and belowground biomass was 544.0 in 2.03 and 559.4 g Cm"2.in 2.04, which coincided with the NEE absorption capacity (63.1.g C·m-2.in 2.03 and 74.9 g C·m-2.in 2.04) in the corresponding plant growing season.

关键词： Potentilla frutlcosa shrub meadow yearly meteorological conditions CO2.exchange variations meteorological factors aboveground and belowground biomass LAI.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Spatiotemporal dynamics of reclamation and cultivation and its driving factors in parts of china during the last three centuries

引用

Progress in natural Science:Materials International 2004年第7期 53-61+97页

作者： GE Quansheng 1, DAI Junhu 1*, HE Fanneng 1, ZHENG Jingyun 1, MAN Zhimin 2.and zhao Yun 2.1. institute of {2. Science and natural resources research, chinese academy of sciences, beijing 100101, china 2. Center for Historical {2. Studies, Fudan University, Shanghai 2.0433, china) institute of {1. Science and {2. resources research Chinese Academy of Sciences Beijing 100101 China Center for Historical geographic Studies Fudan University Shanghai 200433 China

Different from other similar studies, in this paper, most of the data were excerpted from historical archives and documents, and were used to study the spatiotemporal dynamics of cultivated land resources in{1. during the last 300 years. It is clear that these data may help reveal land use change dynamics and its regional differences, but they may be problematic due to the constraints of the original data in the Ming Dynasty, Conversion of Land Area for the purpose of collecting land taxes, and the deliberate or inadvertent omission of cultivated land area during land surveys, therefore, such data were adjusted to our need. In processing the data, we made great efforts to analyze the historical context of their sources and reduced the possible errors. The results show that the cultivated land area increased most quickly in the early Qing Dynasty, and slowed down after the middle Qing Dynasty, and then was stable in the late Qing Dynasty until 1.49, and has been decreasing since then. It is also found that the cultivated land use varied greatly in different regions. The east of the country was cultivated much more heavily than the west, but in some western provinces cultivated land area increased more quickly. It is considered that the driving factors of such cultivated land area change include the increase of the population, the political issues, and the impacts of wars. {2. environmental factors and the introduction of new crops might also have affected the cultivated land use change in the past 300 years.

关键词： land use china last three centuries.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A preliminary study on the heat storage fluxes of a tropical seasonal rain forest in Xishuangbanna

引用

Science china Earth {1. 2006年第S2期49卷 163-173页

作者： DOU Junxia, ZHANG Yiping, YU Guirui, zhao Shuangju, WANG Xin & SONG Qinghai Xishuangbanna Tropical Botanical Garden, chinese academy of sciences, Kunming 6502.3,{2. institute of geographic sciences and National resources research, chinese academy of sciences, beijing 100101,{2. research Centre for Eco-environmental sciences, chinese academy of sciences, beijing 100085,{2. Graduate University of the chinese academy of sciences, beijing 100049,{2. 1. Xishuangbanna Tropical Botanical Garden Chinese Academy of Sciences Kunming 650223 China 3. research Centre for Eco-environmental {1. Chinese Academy of Sciences Beijing 100085 China 4. Graduate University of the chinese academy of sciences Beijing 100049 China 2. {1. of geographic {2. and National resources research Chinese Academy of Sciences Beijing 100101 China

In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna, the sensible and latent heat storage flux within air column, canopy heat storage flux, energy storage by photosynthesis and ground heat storage above the soil heat flux plate, as well as the ratios of these heat storage fluxes to the net radiation in the cool-dry, hot-dry and rainy season were compared and analyzed based on the observation data of carbon fluxes, meteorological factors and biomass within this tropical seasonal rain forest from January 2.03 to December 2.04. The findings showed that heat storage terms ranged significantly in the daytime and weakly in the nighttime, and the absolute values of sensible and latent heat storage fluxes were obviously greater than other heat storage terms in all seasons. In addition, the absolute values of total heat storage fluxes reached the peak in the hot-dry season, then were higher in the rainy season, and reached the minimum in the cool-dry season. The ratios of heat storage fluxes to net radiation generally decreased with time in the daytime, moreover, the sensible and latent heat storage dominated a considerable fraction of net radiation, while other heat storage contents occupied a smaller fraction of the net radiation and the peak value was not above 3.5%. In the daytime, the ratios of the total heat storage to net radiation were greater and differences in these ratios were distinct among seasons before 1.0}00, and then they became lower and differences were small among seasons after 1.0}00. The energy closure was improved when the storage terms were considered in the energy balance, which indicated that heat storage terms should not been neglected. The energy closure of tropical seasonal rain forest was not very well due to effects of many factors. The results would help us to further understand energy transfer and mass exchange between tropical forest and atmosphere. Moreo

关键词： heat storage flux energy closure tropical seasonal rain forest Xlshuangbanna.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A New Analytical Method of the Water resources Allocation in{1.

A New Analytical Method of the Water Resources Allocation in...

引用

2.1.年环境污染与大众健康学术会议

作者： Yanqi zhao1 2.3 Changming liu1 Ying YANG2.Hongxing ZHENG1 1{2. of geographic sciences and natural resources research CAS beijing 100101 china 2.2. of resources & Environment Henan Polytechnic University(HPU) Jiaozuo Henan 45400 china 3Graduate University of chinese academy of sciences beijing 100101 china

The paper introduces the Gini coefficient of economics as a new method of analyzing the inter-provincial allocation of water resources in *** calculated the Gini coefficient for selected indices based upon the statistical data for each province from 1.97 to {1.08,respectively taking the population,GDP and the cultivated area as the basic matching ***,we proposed two novel indexes:the Dependence Coefficient to weigh the degree of reliance on the surface water or groundwater for the separated regions and the Burden Coefficient of water use to judge the efficiency and the level of fairness of water consumption by different *** results show that the allocation of water resources calculated per capita,per unit GDP and per unit area of arable land is very *** particular,some provinces located north of the Yangtze River lack water resources and strongly depend on the *** water efficiency is there lower than in other parts of ***,in order to alleviate the water stress in the northern provinces of the country,an improvement of the technological level of water resources exploitation and utilization and also the restructuring of the economic activity are necessary.

关键词： water resources allocation Gini coefficient Dependence Coefficient Burden Coefficient

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Spatial Characteristics of Soil Organic Carbon Storage in china's Croplands

引用

Pedosphere 2005年第4期15卷 417-423页

作者： WANG Shao-Qiang YU Gui-Rui zhao Qian-Jun NIU Dong CHEN Qing-Mei WU Zhi-Feng institute of {1. {2. and natural resources research Beijing 10010 （China）. Guangdong institute of Eco-Environment and Soil Science Guangzhou 510650 （China）

The soil organic carbon (SOC) pool is the largest component of terrestrial carbon pools. With the construction of a geographically referenced database taken from the second national general soil survey materials and based on 1.46 typical cropland soil profiles, the paddy field and dryland SOC storage among six regions of{1. were systematically quantified to characterize the spatial pattern of cropland SOC storage in{1. and to examine the relationship between mean annual temperature, precipitation, soil texture features and SOC content. In all regions, paddy soils had higher SOC storage than dryland soils, and cropland SOC content was the highest in Southwest{1.. Climate controlled the spatial distribution of SOC in both paddy and dryland soils, with SOC storage increasing with increasing precipitation and decreasing with increasing temperature.

关键词： carbon storage cropland soil organic carbon spatial characteristics

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Comparative study of the net exchange of CO2.in 3 types of vegetation ecosystems on the Qinghai-Tibetan Plateau

引用

Science Bulletin 2005年第16期 97-104页

作者： zhao Liang1, LI Yingnian1, zhao Xinquan1, XU Shixiao1, TANG Yanhong2. YU Guirui3, GU Song1, DU Mingyuan4 & WANG Qinxue3 1. Northwest Plateau {2. of Biology, the chinese academy of Sci-ences, Xining 810001, china 2. National {2. for Environmental Studies, Tsukuba, Ibaraki3050053, Japan 3. {2. of geographic sciences and natural resources {12.,beijing 100101, china 4. National {2. for Agro-Environmental Science, Tsukuba, Ibaraki3058604, Japan

Using the eddy covariance method,from 1.July2.03 to 30 June 2.04, we conducted the observation andanalysis of ecosystem CO2.flux in 3 types of alpine meadowvegetation (Kobresia humilis, Potentilla fruticosa shrub andKobresia tibetica swamp meadows) on the Qinghai-TibetanPlateau. The results show that the Kobresia humilis meadow,the shrub meadow and the swamp meadow’s highest CO2.ptake rates are 1..78, 1..42.and 1..57 μmol·m?2.s?1.espectively, while their highest CO2.release rates are 8.2.,7.73 and 1..67 μmol·m?2.s?1.respectively. The Kobresiahumilis meadow and shrub meadow’s annual atmosphericuptakes are 2.2.g CO2.m2.and 53 g CO2.m2. respectively,while swamp meadow’s annual atmospheric release is 478 gCO2.m2. This proves that the Kobresia humilis meadow andthe shrub meadow on the Qinghai-Tibetan Plateau haverelatively low potential for CO2.uptake and release comparedto C4 grasslands, a number of lowland grasslands, andforests. Moreover, swamp meadow has relatively high releasepotential. This, in turn, reveals clear differences in carbonsource/sink between different types of vegetation in theQinghai-Tibetan Plateau alpine meadow ecosystem. Thesedifferences are mainly brought by differences in thevegetations’ photosynthetic capacity and soil respiration.

关键词： Qinghai-Tibetan Plateau net ecosystem CO2.exchange eddy covariance method.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Characterizing CO_2.fluxes for growing and non-growing seasons in a shrub ecosystem on the Qinghai-Tibet Plateau

引用

Science china Earth {1. 2005年第Z1期48卷 133-140页

作者： XU Shixiao, zhao Xinquan, FU Yuling, zhao Liang, LI Yingnian, CAO Guangmin, GU Song, WANG Qinxue & DU Mingyuan Northwest {2. of Plateau Biology, chinese academy of sciences, Xining 810001, china {2. of geographic sciences and natural resources research, chinese academy of sciences,{12., china Graduate School of the chinese academy of sciences, beijing 100136, china National {2. for Environmental Studies, Tsukuba 305-8569, Japan National {2. for Agro-Environmental Science, Tsukuba 305-8604, Japan Northwest institute of Plateau Biology Chinese Academy of Sciences Xining 810001 China Graduate School of the chinese academy of sciences Beijing 100136 China Northwest institute of Plateau Biology Chinese Academy of Sciences Xining 810001 China institute of {1. {2. and natural resources research Chinese Academy of Sciences Beijing 100101 China National institute for Environmental Studies Tsukuba 305-8569 Japan National institute for Agro-Environmental Science Tsukuba 305-8604 Japan

To assess carbon budget for shrub ecosystems on the Qinghai-Tibet Plateau, CO2.lux was measured with an open-path eddy covariance system for an alpine shrub ecosystem during growing and non-growing seasons. CO2.flux dynamics was distinct between the two seasons. During the growing season from May to September, the ecosystem exhibited net CO2.ptake from 08:00 to 1.:00 (beijing Standard Time), but net CO2.emission from 1.:00 to 08:*** CO2.uptake appeared around 1.0}00 with values of 0.71. 1.1., 1.46 and 0.67 g CO2.-2.h-1.for June, July, August and September, respectively. Diurnal fluctuation of CO2.flux showed higher correlation with photosynthetic photon flux density than temperature. The maximum net CO2.influx occurred in August with a value of 2.7 g CO2.m-2. The total CO2.uptake by the ecosystem was up to 583 g CO2.m-2.for the growing season. During the non-growing season from January to April and from October to December, CO2.flux showed small fluctuation with the largest net CO2.efflux of 0.30 g CO2.m-2.h-1.in April. The diurnal CO2.flux was close to zero during most time of the day, but showed a small net CO2.efflux from 1.:00 to 1.:00. Diurnal CO2.flux, is significantly correlated to diurnal temperature in the non-growing season. The maximum monthly net CO2.efflux appeared in April, with a value of 1.5 g CO2.m-2. The total net CO2.efflux for the whole non-growing season was 356 g CO2.m-2.

关键词： alpine shrub ecosystem, CO2 flux, carbon dynamics, growing season, non-growing season.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

基于Landsat 8影像提取豫中地区冬小麦和夏玉米分布信息的最佳时相选择

引用

作物学报 2024年第3期50卷 721-733页

作者：赵荣荣丛楠赵闯中国科学院地理科学与资源研究所拉萨高原生态试验站北京100101 中国农业大学资源与环境学院北京100193

遥感技术对大尺度农业实时监测提供了一个理想的手段,遥感影像植被分类的最佳时相对作物种植面积遥感监测非常重要。本文选取2.2.年至2.2.年的6景Landsat 8影像,覆盖了夏玉米从乳熟到收获、冬小麦从越冬到成熟的生育期,以此分析不同时... 详细信息

遥感技术对大尺度农业实时监测提供了一个理想的手段,遥感影像植被分类的最佳时相对作物种植面积遥感监测非常重要。本文选取2.2.年至2.2.年的6景Landsat 8影像,覆盖了夏玉米从乳熟到收获、冬小麦从越冬到成熟的生育期,以此分析不同时相的冬小麦-夏玉米与其他地类在光谱特征和NDVI上的差异,通过决策树的方法提取豫中地区冬小麦-夏玉米的空间分布情况。结果表明,冬小麦-夏玉米在不同生长发育时期,提取到的面积比有所不同,对于夏玉米而言,乳熟时期的提取效果要优于之后的时期,其在2.2.年8月2.日的总体精度最高,为83.60%,Kappa系数为0.72.分类质量很好;对于冬小麦而言,最佳识别时期则处于冬小麦的越冬期,其在2.2.年1.1.的总体精度最高,为92.36%,Kappa系数为0.81.信息提取效果很好。除了作物自身生长过程的覆盖度变化,分类精度随成像时间而改变。多时相信息提取也发现,受到天气等环境条件限制,夏玉米和冬小麦的种植区域不完全重叠,山区冬季不适合冬小麦种植从而没有与夏玉米出现重叠分布。本研究有助于我们从宏观上对作物分布及生长状况作出及时有效的判断,对农业监测,特别是对轮作农田的信息管理和作物物候、种植面积等研究具有广阔的应用前景。

关键词：冬小麦-夏玉米光谱特征决策树分类分类精度 Landsat 8-OLI遥感影像

来源：

维普期刊数据库博看期刊

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A distributed spatial computing prototype system in grid environment

引用

Science china(Technological {1.) 2010年第S1期53卷 25-32页

作者： WU Lun,YAN MengLong,GAO Yong,YANG ZhenZhen,zhao Yong & CHEN Bin {1. of Remote Sensing and {2. Information System,Peking University,beijing 1.0871.china 1. institute of Remote Sensing and {1. Information System Peking University Beijing 100871 China

Digital Earth has been a hot topic and research trend since it was proposed,and Digital{1. has drawn much attention in *** a key technique to implement Digital{1.,grid is an excellent and promising concept to construct a dynamic,inter-domain and distributed computing *** is appropriate to process geographic information across dispersed computing resources in networks effectively and cooperatively.A distributed spatial computing prototype system is designed and implemented with the Globus *** important aspects are discussed in *** architecture is proposed according to the characteristics of grid firstly,and then the spatial resource query and access interfaces are designed for heterogeneous data *** open-up hierarchical architecture for resource discovery and management is represented to detect spatial and computing resources in grid.A standard spatial job management mechanism is implemented by grid service for convenient *** addition,the control mechanism of spatial datasets access is developed based on *** prototype system utilizes the Globus Toolkit to implement a common distributed spatial computing framework,and it reveals the spatial computing ability of grid to support Digital{1..

关键词： distributed geographic information processing grid computing Digital china GIS

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：