首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Tourism of China in the 21st century is facing opportunities and challenges never encountering before. On the one hand, Chinese tourism has achieved historic progress from nothing to something, from small to big and from weak to strong following the development experience of reform and opening to the outside world over the past 20 years, which has carried into execution of development strategies from a big tourist country in Asia to a strong tourist country in the world[1]. In the first 20 ye…  相似文献   

3.
This paper examines the changing regional distribution of grain production in China. Based on the analysis of data from county statistics for the period 2000–2003, major differences in the main grain-output regions in China can be observed. The main grain-producing areas have shifted from the south to the north of China. New grain production regions have been also added to western China since the late 1990s. The per capita grain consumption in one third of China’s main grain-producing counties has fallen below 400 kg; most of these areas are located in southern China. In the new millennium, Northeast China, the central-south North China, and the arid and semi-arid regions of Northwest China produced three quarters of the surplus grains. Most of these areas are located in regions susceptible to environmental change. The amount of grain production in these regions shows high fluctuations. It is argued here that further studies of recent environmental changes as well as a risk assessment of China’s food security in main grain-output regions are needed.  相似文献   

4.
21世纪中国主要粮食产区的空间格局特征   总被引:1,自引:0,他引:1  
Grain production is an important issue for the national economy and the livelihood of the Chinese people. It serves as the foundation of national development and social stability. China is a major grain producer as well as a major grain consumer. The grai…  相似文献   

5.
21世纪人地关系研究前瞻   总被引:56,自引:8,他引:56  
郑度 《地理研究》2002,21(1):9-13
人地关系包括人对自然的依赖性和人的能动地位 ,人与自然关系的内涵随着人类社会的发展而发生变化。人地关系研究是近代地理学发展的基础 ,地理学中流行的环境决定论、可能论、文化景观学和人类生态学等都是聚焦于人地关系研究的不同学派。地球系统科学领域的研究重心是揭示人与自然的相互作用及所应采取的对策。信息时代人地关系的特征与工业时代有较大差别。人与自然的作用方式和强度将有显著不同 ,人类将全面系统地深化对自然的认识 ,人类活动空间将发生巨大变化 ,时空观念正在发生转变。知识与科技的作用 ,正成为社会经济发展的主要驱动力。由于地球的整体性和地球各圈层的相互作用 ,许多全球环境问题成为世界各国和社会公众关切的热点。人地关系研究的重要前沿领域包括 :全球环境变化及其区域响应 ,区域可持续发展及人地关系机理调控 ,社会生态与环境伦理研究与体系构建  相似文献   

6.
IPCC-AR4模式对中国21世纪气候变化的情景预估   总被引:41,自引:3,他引:38  
江志红  张霞  王冀 《地理研究》2008,27(4):787-799
利用政府间气候变化委员会(IPCC)第四次评估报告提供的13个新一代气候系统模式的模拟结果,分析了不同情景下(高排放SRES A2、中等排放A1B、低排放B1)中国区域未来100年的气候变化。结果表明,21世纪中国气候预估显著变暖、变湿,世纪末变暖范围在1.6℃~5℃之间,年降水量增加1.5%~20%。在A2、A1B和B1情景下,21世纪末期增暖幅度依次为5.3℃、4.3℃和2.8℃,平均3.5℃,年降水量预估增加依次为11%、9.6%和6.4%,平均达7.5%。气温和降水变化的地理分布显示:北方增温幅度大于南方,降水的增加也主要集中在北方。冬季变暖最明显,降水则在冬、春季增加较显著。模式预估结果的不确定性分析表明,新一代全球系统模式对21世纪中国气候变化预估的可靠性得到了提高。  相似文献   

7.
We study the changing volumes and costs of the energy resources available in the coming century as a result of exploration, technical progress, and consumption. The most reliable and well-documented information involves fossil fuels, which account for nearly 80 percent of the energy mix today. Known and presumed resources are fairly well ranked by cost, and we can estimate future developments. We present two consumption scenarios: the more contrasted reference case and the ecologically driven case presented by the World Energy Council at its last congress (1992). Our scenarios take into account the twofold goal set forth at the Rio summit: to achieve sustainable development and to minimize the climatic effects of pollutant emissions.We show that the most cost-effective mineral resources, including uranium, will run out only gradually in the next century according to these hypotheses. As a result, marginal cost will grow relatively slowly. However, we presuppose a tough policy on curbing consumption and using renewable sources of energy.We point out the need for better cost ranking of energy saving and energy switch possibilities. Additionally, the ecological impact and cost of corrective measures will have to be evaluated. We believe that the medium- and long-term difficulties will stem chiefly from the contradiction between low energy prices and the commitments required. The danger of geopolitical tension will remain a serious concern.  相似文献   

8.
新时期我国中心城市人口城镇化特征及其空间格局   总被引:1,自引:0,他引:1  
在新一轮城镇化进程中,以人力资本为核心的创新经济逐步成为推动经济增长的动力引擎,省域中心城市作为人口聚集地的功能日益凸显。人口流动倾向影响着不同规模和行政等级城市之间的城镇体系重构,选取各个省域典型城市作为重点分析对象,通过我国城市人口最新数据统计测算,揭示出近期全国城镇化发展态势与大都市区域格局变化特征。结果发现,我国人口城镇化发展态势逐渐趋于平稳,不同地区、不同规模城市对人口的吸纳能力仍存在显著差异,各类直辖市、省会城市、副省级城市在人口集聚方面表现突出,传统港口城市、工业城市、省域副中心城市的人口吸引力逐步趋弱。其中,一级城市人口吸纳能力超强,二级城市成为人口重要集聚地,三级城市人口增速趋缓,四级城市人口吸引力平稳;可将之划分为“高/低规模”“高/低增长”四种不同组合类型。同时,城市人口的增长变化和人力资本竞争,显著影响了城市区域经济发展,特别是中西部地区省域中心城市实力日益增强,人口增长强劲,进而改变了传统东中西区域经济显著分异的格局,省会城市首位度表现出“高/低位序”“高/低集中”四种不同组合分布特征,且集中于“高位序、高集中”和“低位序、低集中”两种类型,分化格局相对明显。伴随着中国大都市的不断发育成熟,其逐步成为新时代创新经济和人口集聚的引领者。  相似文献   

9.
21世纪初中国海岸带土地利用空间格局特征   总被引:15,自引:1,他引:14  
侯西勇  徐新良 《地理研究》2011,30(8):1370-1379
基于GIS空间分析技术、条带分割法以及优势度和土地利用程度综合指数,分析了21世纪我国海岸带区域(海岸线向陆30km范围)土地利用的数量、结构、空间格局和集约化特征。研究表明:21世纪我国海岸带土地利用以耕地、林地和建设用地为主。距海远近不同,土地利用的结构特征和空间格局差异显著,水域和建设用地的向海特征最为显著,其次...  相似文献   

10.
21世纪初中国土地利用变化的空间格局与驱动力   总被引:18,自引:15,他引:18  
Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the "Grain for Green" policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of "Western Development", "Revitalization of Northeast", coupled with rapidly economic development during this period.  相似文献   

11.
Land use and land cover change as the core of coupled human-environment systems has become a potential field of land change science (LCS) in the study of global environmental change. Based on remotely sensed data of land use change with a spatial resolution of 1 km × 1 km on national scale among every 5 years, this paper designed a new dynamic regionalization according to the comprehensive characteristics of land use change including regional differentiation, physical, economic, and macro-policy factors as well. Spatial pattern of land use change and its driving forces were investigated in China in the early 21st century. To sum up, land use change pattern of this period was characterized by rapid changes in the whole country. Over the agricultural zones, e.g., Huang-Huai-Hai Plain, the southeast coastal areas and Sichuan Basin, a great proportion of fine arable land were engrossed owing to considerable expansion of the built-up and residential areas, resulting in decrease of paddy land area in southern China. The development of oasis agriculture in Northwest China and the reclamation in Northeast China led to a slight increase in arable land area in northern China. Due to the “Grain for Green” policy, forest area was significantly increased in the middle and western developing regions, where the vegetation coverage was substantially enlarged, likewise. This paper argued the main driving forces as the implementation of the strategy on land use and regional development, such as policies of “Western Development”, “Revitalization of Northeast”, coupled with rapidly economic development during this period.  相似文献   

12.
Zhang  Chi  Wu  Shaohong  Leng  Guoyong 《地理学报(英文版)》2020,30(8):1219-1232
Journal of Geographical Sciences - Based on simulations by the Beijing Climate Center climate system model version 2 (BCC-CSM2), the possible changes in net primary productivity (NPP) of the...  相似文献   

13.
<正> 目前,人们对于森林和森林经营给予了前所未有的关注。尤其是1992年环发大会(UNCED)以来,林业界和其它有关人士对可持续森林经营的清楚的定义和实施进行了许多思考。国际机构,包括森林政府间论坛(IFF),联合国森林论坛(UNFF)和为数众多  相似文献   

14.
未来气候变化情景预估是制定气候变化应对和适应策略的科学基础。本文利用参与耦合模式比较计划第五阶段(CMIP5)的30个气候模式的模拟数据,通过评估各模式对历史气候变化的模拟能力,筛选出模拟区域气候变化的最优模式组合,进而建立偏最小二乘回归(PLS)集合预估模型,据此利用最优模式模拟结果预估区域温度和降水变化情景。通过与历史数据的对比,研究发现本文基于最优模式建立的PLS集合预估模型不仅优于传统的多模式集合平均,而且也优于利用全部模式建立的PLS集合预估模型,体现了模式优选过程的重要性。本文基于优选模式的PLS集合预估模型预估结果表明:① 21世纪各区域温度将持续上升,且冬半年升温速率总体大于夏半年,北方地区升温速率总体高于南方地区;RCP 4.5排放情景下温度上升先快后慢,转折点出现在21世纪中期,RCP 8.5排放情景下,呈持续增加趋势,至21世纪末的升温幅度约为RCP 4.5情景的2倍。② 21世纪各区降水变化均呈显著增加趋势,并表现出高排放情景大于低排放情景,少雨区大于多雨区的特征,但是降水增加过程伴有明显的年代际波动。对比发现,传统的等权重集合平均全部模式(EMC)方法预估的中国夏季变暖速率高于冬季,且降水基本呈线性增加,有悖于全球变暖的基本特征及中国降水具有鲜明的年代际变化特征的基本认识。因而,本文预估的温度和降水变化特征均更符合中国气候变化的基本规律。  相似文献   

15.
This paper draws on theoretical discussions of world cities to analyze socio-spatial polarization and (re-)distribution of deprived groups in Hong Kong in the 2000s. Intensifying global economic restructuring processes have induced socio-economic polarization, thereby producing deprived groups although the spatial outcomes may depend on the city-specific context. When local policies do not counteract the polarization trend, a spatial manifestation of widening socio-economic gaps can be expected. Intensified pro-growth policies adopted since Hong Kong’s return to Chinese rule in 1997 and during its economic recession in the early 2000s have worsened the impact of globalization-induced socio-economic and spatial restructuring. Census data from 2001 and 2011 show increasingly differentiated socio-economic profiles at the district level. The analysis offered in this study also points to a decreased socially mixed society in 2011 when the deprived groups lived in districts with less presence of the advantaged population.  相似文献   

16.
<正>Solution chemistry covers a broad and interdisciplinary area in chemistry,physics,biology,pharmaceutical,and medical sciences,as well as various application fields. With the advent of new theories,analytical methods,computers,and technology,the research area of solution chemistry has now been widely and deeply  相似文献   

17.
In this issue, we feature an article by W. David Menzie, a research geologist with the U.S. Geological Survey, Reston, Virginia. Dr. Menzie is a leading expert on quantitative mineral-resource assessment. He has made significant contributions to quantitative assessment methodologies through the development of spatial mineral deposit density models, grade and tonnage models, and the design of metrics for describing mineral deposit occurrences. He has also studied the geology and mineral resources of the Circle quadrangle, Alaska. Dr. Menzie earned a B.S. degree in geology from Dickinson College, an M.S. in geology, an M.A. in statistics, and a Ph.D. in Geology from the Pennsylvania State University.  相似文献   

18.
在“一带一路”与“中蒙俄经济走廊”倡议的背景下,利用人口增减变化率、人口重心、人口密度变化率、人口地理集中度、人口商度等研究21世纪以来俄罗斯的人口增长与空间分布格局变化。结果表明:(1)21世纪以来,俄罗斯人口经历了先降后增的变化过程;中央区的人口显著上升,伏尔加、西伯利亚与远东区均呈下降趋势;莫斯科、圣彼得堡、乌拉尔区、北高加索区南端的联邦主体人口快速增加,西伯利亚区多数联邦主体人口缓慢增加,远东东部、莫斯科外围地域、伏尔加区多数联邦主体的人口缓慢减少,西北区北端联邦主体的人口急剧减少。(2)俄人口空间分布格局变化主要受地区间人口迁移流动的影响。空间上,俄人口重心不断朝西北向迁移,莫斯科市与圣彼得堡市的人口密度快速增加,远东与东西伯利亚区的人口密度缓慢降低,强化了俄人口分界线——“圣彼得堡-图瓦线”。以“圣图线”为界,俄“西密东疏”“欧洲密、亚洲疏”的格局短期不会改变,整体呈“一横、四纵、两团”及若干区域人口集团的空间结构。  相似文献   

19.
21世纪中国地理学发展的若干思考   总被引:16,自引:4,他引:16  
20世纪我国现代地理学的发展取得了辉煌成就,同时也面临着许多挑战和机遇。基于地球系统科学的最新研究成果与发展态势,结合我国地理学发展的自身特点及国家需求,本文从理论研究、方法论、学科建设、能力建设等方面,对21世纪我国地理学发展的若干问题进行了思考和探索。  相似文献   

20.
张雷 《地理研究》2001,20(5):547-554
长期以来长江干流地区始终承担着全国工业化主体发动机的作用。随着国家工业化及城市化进程的加快,21世纪初长江干流地区的这种作用还将得到明显增强。作为全国人地关系最为紧张的地区之一,长江干流地区需从自身特点出发,合理调整地区产业结构和布局方向,以期真正担负起国家和民族发展所赋予的历史使命。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号