12 resultados para Thematic Animacy Reversals
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
(一)蒙古栎红松林动态的研究 本文综述了森林动态模型的基本概念和发展历史,把模型分为生长和演替模型两类,并比较了两类模型的特点和适用条件,详细论述了演替模型的基本原理,分析了早期和最新林窗模型的特点,给出了林窗模型的最新进展,指出森林动态模型的发展趋势为:①、为满足不同用户对模型的要求,模型应向综合总体方向发展;②、随着生理生态学的发展、试验仪器及分析方法的进步,和为了进一步认识森林动态变化的机理,建立树木生长机制过程模型成为另一个必然的发展方向。 随后综合分析了广泛应用于林窗模型中作为描述树高和直径关系的数学函数,通过理论分析和实际观测数据拟合及预测精度检验,表明理查德方程和单分子方程是森林动态林窗模型中描述树高和直径关系的最佳方程。 通过对蒙古栎红松林三个年龄阶段物种和结构动态实际观测数据分析表明,该类型森林的早期阶段以蒙古栎等阳性树种占优势,中期形成红松和阔叶树占优势的混交林,后期以红松占绝对优势。对该类型森林直径分布变化的研究得出:林分发育的早期,阔叶树中大径级木较多,针叶树中小径级木多;在林分发育的后期呈相反分布。用理论概率模型拟合直径分布表明,韦布尔概率分布模型是描述蒙古栎红松林直径分布的最合适函数。 在以上研究结果的基础上,以森林动态斑块理论为基础建立了蒙古栎红松林动态变化的林窗模型FOROAK,该模型包括对树木生长的生物学过程和影响树木生长的环境因子模拟两部分。运行模型用两种不同面积大小的样地分析森林动态,确定蒙古栎红松林林窗面积为0.05ha。以实际调查数据检验模型,证明所得模型能合理预测森林变化过程,在预测树种组成上精度很高。对裸地上森林的模拟表明蒙古栎红松林动态过程复杂,蒙古栎和白桦在林分发育开始占优势后期渐被红松取代。对现实原始林预测显示,森林未来300年变化稳定,红松株数和生物量变化很小。 最后,应用建立的林窗模型研究了同龄纯林林分密度动态,模拟了林分密度、断面积、生物量、叶面积指数和生产力150年的变化,用林分密度效应的3/2法则和产量恒定法则检验模拟结果表明,模拟的林分密度发展与理论预测相符合,通过本文的研究既检验了林窗动态模型又印证了林分密度效应理论。 (二)生物多样性主题信息标准的研究 中国是世界上生物多样性最丰富的国家之一,在多年的调查、研究和保护工作中,已积累了大量的数据资料,因此,被联合国环境规划署挑选参加“发展中国家生物多样性数据管理能力建设及信息系统网络化”项目,该项目的主要内容之一就是了解与生物多样性有关领域的主题信息标准。 主题信息标准部分讨论了生物多样性信息的收集、管理和转换标准,系统而全面地概述了生物多样性有关领域应用的数据分类系统、核心数据集以及与数据获得有关的术语、定义和数据模型,并讨论了各部门在研究和促进生物多样性信息标准化方面的成果和正在开展的工作。涉及的领域有自然和人工生境中的陆地植被、农业、林业、湿地、海岸和海洋,还有保护区、物种和对生物多样性有威胁的因子等专题。 文中讲述了与陆地植被分类有关的土地利用方式和土地覆盖分类等问题,并给出了国际国内应用广泛的植被分类系统。讨论了农业中与生物多样性有直接关系的分类系统,包括土地分类系统、土壤分类系统等。从森林生态系统和土地利用、林权和林政、森林资源调查、评价和监测、森林利用和经营实践、森林环境和可持续发展等几方面讨论了这些主题的概念、术语和数量划分标准。 讨论了湿地分类系统的发展,列举了国内外应用广泛的分类系统。论述了海岸和海洋生境及保护区的分类系统和标准,给出了数据定义和模型。列举了国内外广泛应用的物种命名标准和其发展过程。分遗传多样性、物种多样性和生态系统多样性三个层次讨论了它们受威胁的特点和评价现状,最后分别不同的威胁因子,如:生境丧失和片断化、全球气候变化、酸雨、臭氧层破坏和有毒污染物讨论了它们对生物多样性的威胁特点和评价现状。
Resumo:
利用遥感技术和多元回归方法,分析了东北平原杨树人工林的立地因子与TM(thematic mapper)影像的关系,建立杨树林生长与植被因子和土壤因子的关系,拟合立地因子——林木生长模型。结果表明:在吉林省农安县南部的防护林类型中,以可溶性总盐(X1)和pH值(X2)为影响林木高(H)生长的主导因子,回归方程为:H=8.431-119.699X1+1.617X2(P<0.01);在吉林省农安县北部防护林类型中,以有机质含量(X1)和0.01~0.25mm粒级含量(X2)为影响林木高(H)生长的主导因子,回归方程为:H=16.421+2.616X1-0.089X2(P<0.01)。回归关系达到了显著水平,根据立地因子,可以预测东北平原农田防护林中的双杨快杨(Populus×xiaozhuanica)和北京杨(Populus×beijingensis)的林木生长状况。
Resumo:
以黄土高原为研究区,对该区的水土流失进行系统、宏观、综合的分析,确定了一套适于该区水土流失宏观定量评价的指标体系,并运用GIS技术,对该区影响水土流失的各个因素进行空间分析,实现了多源数据的空间集成和专题信息的提取,建立了适于该区水土流失评价的宏观定量数学模型,并对研究区一定评价年限内的水土流失状况进行了应用评价。
Resumo:
Along with its economic reform, China has experienced a rapid urbanization. This study mapped urban land expansion in China using high-resolution Landsat Thematic Mapper and Enhanced Thematic Mapper data of 1989/1990, 1995/1996 and 1999/2000 and analyzed its expansion modes and the driving forces underlying this process during 1990-2000. Our results show that China's urban land increased by 817 thousand hectares, of which 80.8% occurred during 1990-1995 and 19.2% during 1995-2000. It was also found that China's urban expansion had high spatial and temporal differences, such as four expansion modes, concentric, leapfrog, linear and multi-nuclei, and their combinations coexisted and expanded urban land area in the second 5 y was much less than that of the first 5 y. Case studies of the 13 mega cities showed that urban expansion had been largely driven by demographic change, economic growth, and changes in land use policies and regulations.
Resumo:
Over last two decades, numerous studies have used remotely sensed data from the Advanced Very High Resolution Radiometer (AVHRR) sensors to map land use and land cover at large spatial scales, but achieved only limited success. In this paper, we employed an approach that combines both AVHRR images and geophysical datasets (e.g. climate, elevation). Three geophysical datasets are used in this study: annual mean temperature, annual precipitation, and elevation. We first divide China into nine bio-climatic regions, using the long-term mean climate data. For each of nine regions, the three geophysical data layers are stacked together with AVHRR data and AVHRR-derived vegetation index (Normalized Difference Vegetation Index) data, and the resultant multi-source datasets were then analysed to generate land-cover maps for individual regions, using supervised classification algorithms. The nine land-cover maps for individual regions were assembled together for China. The existing land-cover dataset derived from Landsat Thematic Mapper (TM) images was used to assess the accuracy of the classification that is based on AVHRR and geophysical data. Accuracy of individual regions varies from 73% to 89%, with an overall accuracy of 81% for China. The results showed that the methodology used in this study is, in general, feasible for large-scale land-cover mapping in China.
Resumo:
Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM)+ data have been successfully employed in the field of mineral exploration to identify key minerals over arid and semi-arid terrains. However, redundant vegetation and cloud may seriously interfere with the discrimination of the minerals with diagnostic features. Therefore, in this study, we use masking technique to eliminate the negative influence of vegetation and cloud and Crosta technique to identify the diagnostic features of hydroxyl-minerals, carbonate-minerals and iron oxides. Then the anomalies were endowed with special colours and overlapped with the remote-sensing and geochemical data, overlaying images as remote-sensing anomalies. The mineral exploration work was carried through by synthetic analysis of the remote-sensing images, geochemical data and structures. Finally, areas with high correlation between the occurrence of hydrothermal alteration and presence of main faults and geochemical anomalies were considered as mineral exploration targets worthy of further detailed exploration programmes.
Resumo:
The VEGETATION (VGT) sensor in SPOT 4 has four spectral bands that are equivalent to Landsat Thematic Mapper (TM) bands (blue, red, near-infrared and mid-infrared spectral bands) and provides daily images of the global land surface at a 1-km spatial resolution. We propose a new index for identifying and mapping of snow ice cover, namely the Normalized Difference Snow/Ice Index (NDSII), which uses reflectance values of red and mid-infrared spectral bands of Landsat TM and VGT. For Landsat TM data, NDSII is calculated as NDSIITM =(TM3 -TM5)/(TM3 +TM5); for VGT data, NDSII is calculated as NDSIIVGT =(B2- MIR)/(B2 + MIR). As a case study we used a Landsat TM image that covers the eastern part of the Qilian mountain range in the Qinghai-Xizang (Tibetan) plateau of China. NDSIITM gave similar estimates of the area and spatial distribution of snow/ice cover to the Normalized Difference Snow Index (NDSI=(TM2-TM5)/(TM2+TM5)) which has been proposed by Hall et al. The results indicated that the VGT sensor might have the potential for operational monitoring and mapping of snow/ice cover from regional to global scales, when using NDSIIVGT.
Resumo:
Chinese loess preserved in northwest and north China are famous for its fine grain size, high accumulate rate and high community and can be good archives for paleoclimate and paleomagnetic variation over the later Cenozoic, with which can be correlated well between marine sediments. Major geomagnetic chrons and long term paleoclimate changes in Quaternary are successfully extracted from Chinese loess-paleosols, as well as short-term geomagnetic excursions and climate instability of high resolution. Magneticstratigraphy based on paleogeomagnetic polarity reversal recorded in Chinese loess is a basic project in loess research since decades ago. True geomagnetic records and exact location of geomagnetic reversal boundary in section is the foundation of magneticstratigraphy. Matuyama-Brunhes (MB) reversal as the youngest one still remains divarication about exact location of its boundary (MBB). L8 and S8 of Luochuan and Xifeng located in the interior of Chinese Loess Plateau(CLP) and Mangshan in southeast part of CLP are chosen to make clear some problems which include magnetic mineral, process of MB reversal, location of MBB, downward displacement scale of magnetic reversal boundary, time lag of paleoclimate record by marine and loess, new correlation between Chinese loess and marine sediments. Rock-magnetic investigations carried on L8 and S8 show that the main mineral are ferrimagnetic assemblage consists of magnetite and maghemite in Luochuan and Xifeng, and magnetite in Mangshan, which all contains little hematite belongs to antiferromagnetic phases. The main carrier of nature remanet magnetism (NRM) is detrital magnetite with pseudo-single domain. Detailed paleomagnetic investigations display that there are several rapid reversals in direction during the process of MB reversal which started at the upper part of S8 and finished at the lower part of L8, and lasted about decades of centimeters to more than 100cm correspond to about 104 years. On the assumption that MBB is located in the middle part of the layer which recorded the very reversal, 11cm is considered as the scale of downward displacement for the MBB in Chinese loess after estimation through correlation between Luochuan and Mangshan records. So this study denies the theory of large scale displacement of MBB and large scale Lock-in depth of NRM acquired from Chinese loess. Time lag of paleoclimate records in terrestrial sediments and marine sediments is considered after reassessment of correlation between low field susceptibility of Chinese loess with marine oxygen isotope in benthic foraminifera. On the basis of traditional correlation between Chinese loess and marine oxygen isotope, this study document a new scheme which correlates L8 and S8 to MIS18 and MIS19, respectively.
Resumo:
Two problems are studied in this thesis, the relationship of the magneto-spheric - ionospheric current systems during storms, and the effects of the main field to the space environment. The thesis includes three parts. 1. Magnetic disturbances caused by magnetospheric - ionospheric current systems Transient variations of the geomagnetic field at middle-low latitudes are mainly caused by the ionospheric dynamo current (IDC), the symmetric ring current (SRC), the partial ring current-region II field-aligned current-ionospheric current system (PRFI), and the region I field-aligned current-ionospheric current system (FACI). The storm on May 1 ~ 6, 1998 is analyzed. Firstly, the S_q-field caused by IDC current is removed by using the modified Hibberd's method in which the effect of SRC is considered. The neglect of SRC-field can give as much as 40% error in S_q-field evaluation. Secondly, the disturbance fields at the middle and low latitudes are separated according to their origins. As a result, the disturbance caused by FACI-current is an important part of the asymmetrical depression of H-component in middle and low latitudes during storms. The results show that the relative intensity of the Sq-field increases in the main phase of the storm and decreases in the recovery phase. The latitudinal gradient of the Sq-field is positive during the whole storm. The storm of May 1 ~ 6, 1998 contains two events. In the first event on May 2, the SRC-field is similar to Dst index. But in the second event on May 4 ~ 5, the SRC-field delays to Dst index, and the SRC-field depresses while the PRFI- and FACI-fields recovery. 2. Analysis of S_q~p variation in CGM coordinates In order to study the conjugation of geomagnetic variations between northern and southern hemispheres, we use the corrected geomagnetic coordinates (CGM) instead of the geomagnetic coordinates (GM) to analyze the S_q~P equivalent current system. The CGM coordinates are built up by International Geomagnetic Reference Field (IGRF) model. The S_q~p variations and equivalent current systems in the northern and southern polar regions are more symmetrical in CGM coordinates than in GM co-ordinates. This fact implies that the current distributions in polar regions are governed by the configuration of the geomagnetic field lines. As the elaborate structure of S_q~p current system in quiet time is obtained, we summarize the seasonal variation of the electrojet in quiet time. 3. The magnetospheric configuration of non-parallel-dipole model The magnetospheric configurations are calculated for two possible geomag-netic field models during the geomagnetic field reversals. These models are the dipole field with the axis to the sun and the quadrupole field model. We use the finite element method to solve the magnetic equation, and use the surface evolution method to solve the equilibrium equation. The results show that the main field greatly affects the space environment.
Resumo:
The historical land use and land cover changes is one of the key issues in LUCC research. However, the achievement of China in this field doesn't match her position in the world yet. And the reliability of the quantitive records in Chinese historical literature, the basic data for historical land use research, has been doubted. This research focuses on Re-Cha-Sui, a typical area for the farming-pastoral region in the north of China, to make a detailed case study in this field. Based on a deep mining and calibration on the data from massive historical documents and land-use surveys, the author gives a detailed analysis on the administrative region evolution, historical population dynamics, reclamation policy, and the land statistic system. According to textual researches, parallel validation and physical geographical analysis, a unified land use series for recent 300 years, which founded on the results of modern land-use surveys, is constructed. And the thematic maps on the cultivation index for different counties in several temporal sections are plotted. Based on the endeavor above, the dynamic of forest and steppe is reconstructed as well. The temporal-spatial patterns of land use/land cover changes in the area is analyzed. And the influence of different driving forces are discussed. The main conclusions of the research are as followed: 1. The quantitive records in literatures on Re-Cha-Sui area are reflection of real amounts of croplands. It is practical to reconstruct a result comparable with the modern land-use surveys, based of a deep mining and considerate validation on historical documents. The unexceptional negative attitude towards the numerical records in historical documents is unnecessary. 2. In recent 300 years, 3 climax of reclamation appeared in Re-Cha-Sui area and altered the pure pastoral area into a farming-pastoral region. The interval were respectively the early time till mid time of the Qing dynasty, the end of the Qing dynasty till early time of the Republic of China(ROC), and the time after A.D. 1949. After the first expansion, the area of cropland in this region reached 2.0 million ha. Among them, Guisui area, which was most densely cultivated, had a cultivation index over 30%, which is similar with modern situation. The second expansion covered broader area, and the amount of cropland reached 3.5 million ha. The increase of farming area after 1949 is due to the recultivation of abandoned farmland. The current area of cropland in this region is 5.6 million ha. In the southern area where the land was reclaimed early, the amount on of the cropland has some fluctuation in 300 years. While in the new reclaimed area in the north, the area of cropland has kept the trend of increasing. 3. Due to the different natural conditions, most forests in Re-Cha-Sui area distribute in the mountain area of North Hebei province, and the upland of West Liaoning province, especially the former, which has a forest coverage near 70%. However, most of these forests were destroyed before the end of the Qing dynasty. In 1949, the natural forest near Chengde was nearly cleared up. They were partly renewed after 1949 due to plantation. 4. In the steppe zone such as northern Rehe, Suiyuan and Chahar, the area of steppe has a negative correlation with that of cropland. With the expansion of cropland, the percentage of steppe has shrunk from over 80% to 53%. In the mountain area of North Hebei province, steppe expanded with the shrinkage of forest, though cropland was expanding. The percentage once reached 60%, and then fell with the renew of forest. However, in the upland of West Liaoning province, the steppe shrink slowly from original 50% to current 26%, with the expansion of cropland. 5. The land use and land cover change in Re-Cha-Sui area in recent 300 years is driven by various factors, including human dimensions such as population, policy of the government, disorder of the society, cultural tradition, and natural factors such as climate change and natural disasters. Among them, pressure from surplus population is the basic driving force.
Resumo:
Population research is a front area concerned by domestic and overseas, especially its researches on its spatial visualization and its geo-visualization system design, which provides a sound base for understanding and analysis of the regional difference in population distribution and its spatial rules. With the development of GIS, the theory of geo-visualization more and more plays an important role in many research fields, especially in population information visualization, and has been made the big achievements recently. Nevertheless, the current research is less attention paid to the system design for statistical-geo visualization for population information. This paper tries to explore the design theories and methodologies for statistical-geo-visualization system for population information. The researches are mainly focused on the framework, the methodologies and techniques for the system design and construction. The purpose of the research is developed a platform for population atlas by the integration of the former owned copy software of the research group in statistical mapping system. As a modern tool, the system will provide a spatial visual environment for user to analyze the characteristics of population distribution and differentiate the interrelations of the population components. Firstly, the paper discusses the essentiality of geo-visualization for population information and brings forward the key issue in statistical-geo visualization system design based on the analysis of inland and international trends. Secondly, the geo-visualization system for population design, including its structure, functionality, module, user interface design, is studied based on the concepts of theory and technology of geo-visualization. The system design is proposed and further divided into three parts: support layer, technical layer, user layer. The support layer is a basic operation module and main part of the system. The technical layer is a core part of the system, supported by database and function modules. The database module mainly include the integrated population database (comprises spatial data, attribute data and geographical features information), the cartographic symbol library, the color library, the statistical analysis model. The function module of the system consists of thematic map maker component, statistical graph maker component, database management component and statistical analysis component. The user layer is an integrated platform, which provides the functions to design and implement a visual interface for user to query, analysis and management the statistic data and the electronic map. Based on the above, China's E-atlas for population was designed and developed by the integration of the national fifth census data with 1:400 million scaled spatial data. The atlas illustrates the actual development level of the population nowadays in China by about 200 thematic maps relating with 10 map categories(environment, population distribution, sex and age, immigration, nation, family and marriage, birth, education, employment, house). As a scientific reference tool, China's E-atlas for population has already received the high evaluation after published in early 2005. Finally, the paper makes the deep analysis of the sex ratio in China, to show how to use the functions of the system to analyze the specific population problem and how to make the data mining. The analysis results showed that: 1. The sex ratio has been increased in many regions after fourth census in 1990 except the cities in the east region, and the high sex ratio is highly located in hilly and low mountain areas where with the high illiteracy rate and the high poor rate; 2. The statistical-geo visualization system is a powerful tool to handle population information, which can be used to reflect the regional differences and the regional variations of population in China and indicate the interrelations of the population with other environment factors. Although the author tries to bring up a integrate design frame of the statistical-geo visualization system, there are still many problems needed to be resolved with the development of geo-visualization studies.
Resumo:
Under the direction of Geo-informatic Tupu theory, based on comprehensive natural division in Xinjiang and 1:100000 land use and land cover vector data in 2000 from resource and environment database of CAS, the paper gave out some distribution Tupu of land resource types in different regions of Xinjiang. GIS tools such as ARCTOOLS and ARCV1EW were used to clip the unit of each natural division. Some useful conclusions were established. Then the lower reaches of Tarim River were selected as typical area to analyze the ecological environment evolvement from 2000 to 2004 since the beginning of ecological water delivering. The comprehensive space-time analysis provided a method to monitor the effect dynamically. The main contents of the thesis are listed as follows: (1) Similarities and differences between North Xinjiang and South Xinjiang, 6 second-classified regions and 37 third-classified regions. The conclusion of each region emphasized the percentage of area of main land types, characteristic description and distribution of cultivated land > woodlands grassland-, water area^ urban and rural land and unused land. (2) Thematic Tupu of each region. It concluded artificial oasis Tupu, the proportion between dense-grass% moderate-grass and sparse-grass, pattern of land resources and the land use degree. The artificial oasis mean cultivated land^ woodland^ urban & rural land and other construction land. The proportion of grassland disclosed the quality of all grassland and showed the development of them. Pattern of land resources and the land use degree gave out the detailed development direction and development degree of each region. (3) Ecological environment evolvement of the lower reaches of Tarim River. The effects of each ecological water delivering were compared.