共查询到20条相似文献,搜索用时 11 毫秒
1.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(1-2):5-17
Sparsely populated areas in present-day North West Europe are almost automatically associated with demographic decline, in particular when studied on a local level. An image of an urn-like age pyramid, bulging near the top and with a slim base, presents itself to the observer. But it should not be forgotten that such a situation, with more deaths than births, is a long-term elTect of years and years of net out-migration. The analysis of geographic mobility thus becomes more important than fertility and mortality stud- ies. We want to understand how the age pyramid has become an urn. 相似文献
2.
Allan M. Findlay David Short Aileen Stockdale 《Applied geography (Sevenoaks, England)》2000,20(4):257
An economic audit of the labour-market impact of in-migration to rural Scotland provides evidence that migrants make rather than take jobs. A survey of 689 households in six study areas selected from across rural Scotland provides the basis for examining the scale and nature of job growth associated with in-migration. Job multipliers are calculated by migrant type and by economic sector. 相似文献
3.
Anne-Marie Lott Peter A. Siver Laurence J. Marsicano Kenneth P. Kodama Robert E. Moeller 《Journal of Paleolimnology》1994,12(2):75-86
Remains of scaled chrysophytes, magnetic minerals and pollen were used to analyze the recent paleolimnological history of a small lake, Lake Waynewood, in the Pocono Mountains of Pennsylvania. Important shifts in all three variables were observed over the 133 years represented by the core. The most significant changes occurred near the turn of the century when the watershed was heavily logged. Before the logging event, species such asSynura sphagnicola, S. spinosa, Mallomonas galeiformis andM. duerrschmidtiae were co-dominant members of the flora. Subsequent to the deforestation of the watershed other taxa, includingM. crassisquama, M. caudata andS. petersenii, increased in relative importance. Concurrent with changes in the scaled chrysophytes was a six-fold increase in the concentrations of magnetic material, presumably the result of increased erosion caused by the logging. Changes in pollen grains also correlate well with the onset of the deforestation event. The scaled chrysophyte inferred specific conductivity of the lake has more than tripled, with the primary increase occurring concurrent with the commencement of logging and the increase in magnetic mineral material. The effects of other human-related disturbances are also discussed. 相似文献
4.
Piran C L White Steve Cinderby Dave Raffaelli Annemarieke de Bruin Alison Holt Meg Huby 《Area》2009,41(4):414-424
There has been much debate about the importance of policy-relevant research in geography over the last decade. There has also been an increasing recognition by policymakers of the importance of integrative (interdisciplinary and transdisciplinary) approaches to policy-relevant research. However, geographers have been more reluctant than their colleagues in other social and natural sciences to embrace integrative research collaborations. For integrative research to achieve its full potential and to encourage greater participation from the geographical research community, we need to increase our understanding of its potential value, but also some of the challenges that it poses, and how these can be overcome. In this paper, we consider the processes involved in conducting successful integrative research from the perspective of researchers involved in these projects. We base our analysis on the results of a questionnaire survey of international integrative research programmes on environmental issues in rural areas, combined with our own experiences of working in integrative research. We conclude that effective integrative research depends on the establishment of a clear conceptual framework, the use of appropriate temporal and spatial scales in the research, effective language and communication, time and commitment, and trust and respect. We also highlight the value of stakeholder involvement in integrative research to ensure the policy relevance of the work and provide a mechanism to assist with effective knowledge transfer of the results. 相似文献
5.
Kaistha KC 《Population geography : a journal of the Association of Population Geographers of India》1987,9(1-2):25-36
Using a broadened concept of migration, which includes circulatory migration and commuting, this paper maintains that the patterns of outmigration vary a great deal when the level of development of a rural area is treated as an independent variable. This study uses a stratified conditional sample of 192 households selected from 3 areas: 53 households from a low developed (LDL) area, 56 from a medium (MDL), and 83 from a high (HDL). Data were collected by personal observation, interview, and genealogical methods at both the household and individual level. The households are divided into 3 main categories: 1) non-migrating, 2) commuting only, and 3) migrating (which is further divided into migrating within and migrating outside the boundaries of the district). Results show that 1) 37.51% of household members neither commute nor have migrated outside the village; 2) using the narrow definition of migration, only 10% of males over age 15 migrate, while including commuting in the definition increases the percentage to 40; 3) proportions of non-migrating households decrease from 58.4% for the LDL, to 35.7% for the MDL, to 25.3% for the HDL area; 4) the proportion of commuting only households increases from 26.4% for the LDL, to 35.7% to the MDL, and 55.4% for the HDL area; 5) 15.2% of households in the LDL, 28.6% in the MDL, and 19.3% in the HDL area experience a permanent change in residence; 6) as development accelerates, the overall volume of outmigration increases; 7) the flow of migration from rural to rural areas is mostly limited to the MDL area, while cityward migration increasingly occurs on both LDL and HDL areas; 8) the median age of commuters increases with rising levels of development; and 9) almost all migrants from the LDL area are employed in low prestige occupations, most from the HDL area have higher prestige jobs, and those from the MDL area have both high and low prestige jobs. 相似文献
6.
20 世纪科尔沁的人口变化及其特征分析 总被引:3,自引:0,他引:3
利用蒙、汉、日语多种文献资料就科尔沁近百年的人口变化进行了分析,结果发现: 一个世纪以来科尔沁人口增加很快,平均人口密度从民国初期的2.40 人/km2 增加到2000 年 的39.72 人/km2,约为世纪初的17 倍;新增人口主要为1949 年前的关内流民、1949 年中华人民共和国成立后的移民以及移民生育;人口增加最高峰出现在1949 年后的计划移民时期, 伪满时期的流民则构成了研究区近百年另一个显著的移民高潮;移入人口在科尔沁的分布受 距离农区的空间间隔、科尔沁自然环境条件及其变化、城镇化等因素影响,人口密度呈现从 科尔沁外围到腹地、从农耕区到农牧交错区和牧区、从城镇到农村牧区逐渐降低的空间分布特征,移入人口成为20 世纪科尔沁的农耕主力军。 相似文献
7.
中国山区农村土地利用转型解析 总被引:39,自引:5,他引:34
山区土地开发及其导致的资源环境问题是农业社会人地关系紧张的体现,工业化、城镇化进程中劳动力转移减轻了山区农村土地的人为扰动,由此驱动土地利用发生转型,引发一系列自然和社会经济效应。按照“土地利用转型—驱动力—效应—响应”的分析框架,剖析中国山区农村土地利用转型的特征和规律,提出山区农村土地整治的响应措施。研究表明:① 山区农村土地利用转型体现出土地利用形态在长期变化过程中的趋势性转折,显性形态转型即由农业社会的耕地扩张和林地收缩演变为城镇化进程中的耕地收缩和林地恢复性增长,隐性形态转型即伴随上述过程发生的土地边际化及生态功能恢复;② 社会经济因素主导山区农村土地利用转型过程,劳动力转移引发土地人为扰动减轻是直接驱动力,务农机会成本上升、恶劣的生存环境等引发劳动力转移的因素是更为根本的驱动力;③ 山区农村土地利用转型降低了土地生态系统脆弱性并提高了其生态安全屏障功能,其社会经济效应应聚焦山区农村发展与农户生计安全层面,并亟需实证研究的支撑;④ 当前山区农村土地利用转型是自然恢复和生态优化的良性过程,有着经济社会发展的必然规律,山区农村土地整治要顺应其土地利用转型规律,目标导向从耕地数量增加转向生态环境保护与社会经济福祉协同提升。 相似文献
8.
我国20世纪工业地理学的发展 总被引:12,自引:2,他引:10
我国工业地理学发轫于20世纪初,在经历了启蒙和成长两个阶段后,终于成为经济地理学的一个重要分支学科。作为一门实证性学科,我国工业地理学面临国家工业化转型所带来的巨大挑战。为此,实现以政府主导布局的传统理论思维向以市场主导布局理论思维的转变强调空间扩散和空间重组的协调发展和现实布局实践的科学总结将 国工业地理学未来发展的三个最重要和最基本的方向和任务。 相似文献
9.
论北京农村空间的商品化与城乡关系 总被引:3,自引:0,他引:3
基于后生产主义理论,讨论了北京农村空间的商品化与城乡关系问题,并从理论抽象方面取得了以下认识:(1) 无论农村与城镇,空间是一种抽象的概念,理论上,自然界的纯粹空间不具有商品价值意义。空间的商品化是与一定的人类经济生产活动和生产方式相联系而存在和逐步显现的;(2) 在经济全球化与可持续发展的背景下,随着社会经济力的增强、后生产主义思想的蔓延,人类生产活动日益丰富,空间的商品化也进一步显现;(3) 改革开放以来,北京农村的景观、土地利用、就业、生活形态、旅游业的快速发展使得北京农村空间生产内容发生了巨大变化,多样化愈趋增强,北京农村空间的商品性也日益突出;(4) 随着农村空间商品化的发展,北京地区的城乡差距逐步缩小,北京地区长期扭曲的城乡关系得到一定程度的纠正。 相似文献
10.
18世纪以来塔里木河干流河道变化及其与人类活动的关系 总被引:2,自引:0,他引:2
塔里木河是南疆主要的经济生活水源,其河道变化会引起绿洲变化,从而导致人类活动发生变化。学者虽对历史时期的塔河变化有研究,但对18世纪以来的河道变化缺乏细致的研究,这一时期是人类活动对环境影响日益增多的时期。在野外考察基础上,借助历史文献、历史地图对塔河干流沙雅以上和以下段分别进行研究,结果显示,18世纪20年代,塔河干流分南河、北河; 18世纪50年代,南河与北河合为一条,沿北河位置行水; 至19世纪10年代,塔河干流南移,在南河(即大干河)位置行水; 以后至20世纪10年代,沙雅及其以上河段再次北移,沿北河位置行水,以下河段仍沿南河位置行水,称叶尔羌河或塔里木河。至迟在40年代中期,沙雅以下河段向北迁移,沿渭干河行水,形成现代塔里木河河道。20世纪以前河道变化主要受自然气候变化所导致的河水量变化及河流自身运行规律影响比较大,在河道淤积基础上,水量变化是河流改道的主要原因; 以后受人类农业生产的影响日益加大。 相似文献
11.
本文根据1901年以来的62次强火山(VEI≥4)喷发年表和英国东安格利亚大学气候研究中心发布的格点气温资料(CRU TS v.3.22),采用时序叠加分析方法,辨识了不同纬度、不同季节强火山喷发对中国温度变化区域差异的影响。结果表明:不同纬度强火山喷发后的1~2年,中国温度基本以下降为主,但降温强度存在显著的区域与季节差异。高纬火山喷发后的显著降温区域发生在东北和东南地区,冬半年温度下降达1.2°C,夏半年温度下降2.0°C;中低纬火山喷发后,冬半年温度的显著下降区域发生在青藏、东南和东中部地区,幅度为1.3~2.2°C,夏半年温度下降幅度比冬半年小;赤道火山喷发后,冬半年温度显著下降区域发生在东北、东南和青藏地区,且降温幅度均大于1.2°C,夏半年西北和东中部地区降温幅度偏小。此外,强火山喷发后第3年,部分地区还出现二次降温现象,降幅甚至超过第一次;然而,同一纬度强火山喷发后,其所造成的降温幅度和降温区域差异与强火山喷发的季节关系不大。 相似文献
12.
20世纪中国气候变化研究 总被引:2,自引:0,他引:2
Studies on the 20th century climate change in China have revealed that under the background of global warming over the past century,climate in China has also experienced significant change with mean annual temperature increased by about 0.5 °C.More reliable results for the latter part of the 20th century indicate that the largest warming occurred in Northwest China,North China and Northeast China,and the warming in winter is most significant.Although no obvious increase or decrease trends were detected for mean precipitation over China in the past half century,regional differences are very distinct.In the middle and lower reaches of the Yangtze River,precipitation increased,while that in the Yellow River Basin markedly decreased.Studies suggest that climate change in China seems to be related not only with the internal factors such as ENSO,PDO,and the others,but also with the anthropogenic effects such as greenhouse gas emissions,and land use.The future climate change studies in China seem to be important in narrowing understanding the nature of China's climate change and its main causes,since it is significant for projection and for impact assessment of climate change in the future. 相似文献
13.
《自然地理学》2013,34(3):208-224
River regulation has systematically increased along much of the Mississippi River throughout the 20th century. There is only a cursory understanding of changing hydrological processes along the entire length of the Mississippi River over this same time period. This study compared four measures of river hydrology, at the beginning (1910-1930) and at the end of the 20th century (1980-2000). River-stage data were statistically analyzed from 15 equidistant gauges along the main stem of the Mississippi River. The findings revealed (1) significant changes in components of river hydrology between both time periods and (2) varying patterns of change between the different river segments. The Upper Mississippi River (UMR) experienced significant increases in peak, mean, and minimum monthly stages between the periods, while variance of these same stage conditions declined. The Middle Mississippi River (MMR) exhibited significant increases in the magnitude and variance of river stages. The frequency and duration of flood stages increased between the two periods on the MMR. The Lower Mississippi River (LMR) demonstrated a mixed response during this time period. Gauges at the upper and lower end of the LMR changed similarly to the gauges on the UMR. However, gauges on the central part of the LMR showed decreases in peak, mean, and minimum river stages. 相似文献
14.
西北贫困地区乡村类型识别与振兴途径研究 总被引:11,自引:2,他引:11
乡村振兴战略是新时期我国推进城乡融合发展的重要举措。贫困地区既是脱贫攻坚的主战场,又是乡村振兴的重点区域。如何科学识别村落类型,分类推进典型区域乡村振兴发展,对于破解农村发展不平衡不充分问题具有重要的现实意义。本文解析了乡村地域系统发展理论,阐释了城乡融合发展理论,剖析了村域空间结构格局演变和城乡要素结构功能优化重组;构建了西北干旱贫困地区乡村振兴村落类型识别体系,从乡村主体、产业发展、人居环境、资源禀赋4个子系统进行逐级分类判断,识别乡村主导类型,结合专家征询分析与村落特征,将乡村振兴村落类型识别为集聚提升类、三产融合类、城郊融合类、特色保护类、搬迁撤并类,结合不同乡村振兴模式提出了相应地发展路径,以期为乡村振兴提供理论依据与决策参考。 相似文献
15.
北极地区20世纪温度变化趋势的不确定性 总被引:2,自引:0,他引:2
北极作为地球的冷源之一,对于地球气候系统起着重要的调节作用.本研究通过分析和总结北极地区器测数据和模拟集成结果,以及最近2 000 a来的温度记录,得出如下结果:1)格陵兰冰盖表层大气温度记录显示,20世纪存在1923—1965年和1994年—至今2个相对温暖时段,且前者更为温暖,温度变化幅度远大于北半球的平均温度.2)北极地区20世纪温度上升是客观存在的,其夏季温度和年平均温度呈现一致变化,未发现明显的温度异常信号.3)定量重建的古气候记录显示了北极地区20世纪升温的特征,但不同记录揭示的升温幅度存在差异.与器测结果不同,多条重建记录未能揭示自1994年至今的升温阶段,反映了古气候载体对气候响应的复杂性,揭示出北极地区未来气候变化趋势存在不确定性.在全球变化备受关注的背景下,北极地区对气候变化研究的重要性日益显现,在做出明确结论之前,需要进一步加大研究力度. 相似文献
16.
17.
20世纪以来土地利用研究综述 总被引:15,自引:0,他引:15
介绍和分析了土地利用和土地变化的研究进展,为开展土地利用变化研究提供借鉴。在20世纪90年代以前,土地利用研究主要围绕土地利用调查、土地资源评价、土地利用规划等开展。20世纪90年代以后,土地利用变化研究呈现综舍化研究的趋势。研究内容、研究理念发生了根本的变革,在研究方法与手段、驱动机理、地区案例研究等方面取得了系列的成果。 相似文献
18.
19世纪后半叶至20世纪初叶梅雨带位置的初步推断 总被引:5,自引:0,他引:5
提取《湘绮楼日记》中1869~1916年间长沙、衡阳地区夏半年(4~9月)的逐日天气记录,重建4~9月逐旬平均降水日数序列和6~7月逐候平均降水日数序列,与现代(1951~1980)长沙气象观测数据进行对比,发现当时梅雨期结束于7月3候,较现代推迟2候;梅雨持续时间2~3旬,比现代长约1旬。参考物候信息(历年平均蝉始鸣日期)得出结论:19世纪后半叶至20世纪初,冬季风势力强于现代,压制了副热带高压北进,当时梅雨带位置较现代偏南1~2个纬度。长衡地区因此较现代更接近梅雨带中心,出现了更明显的梅雨。 相似文献
19.
The theory on the cyclic adaptation between society and ecosystems sheds new light on the evolution and internal structure of human–environment systems. This paper introduces the risk index(RI) and adaptation capacity index(ACI) to evaluate the rural human–environment system. An evaluation index system for the adaptability of rural human–environment systems is configured in the context of climate change and policy implementation. On this basis, the stages, features, dominant control factors, and evolution mechanism were examined vis-à-vis the adaptability of the rural human–environment system in Darhan Muminggan Joint Banner from 1952 to 2017. The main results are as follows:(1) The evolution of the rural human–environment system can be divided into three stages, namely, the reorganization and rapid development stage(1952–2002) with population, cultivated land, livestock and degraded grassland increasing by 260%, 13%, 134% and 16.33%, respectively. The rapid to stable development stage(2003–2010) with population increasing by 2.8%; cultivated land, livestock and degraded grassland decreasing by 2.3%, 13.6% and 10.7%, respectively. The stable to release stage(2011–2017) with population, cultivated land, livestock and degraded grassland decreasing by 2.6%, 0.2%, 10.6% and 3.8%, respectively.(2) With the passage of time, the ACI of the rural human–environment system first increased slightly(–0.016–0.031), followed by a slight decline(0.031–0.003), and culminating in a rapid increase(0.003–0.088). In terms of spatial patterns, adaptability is high in the middle, moderate in the north, and low in the south.(3) The evolution of adaptability in the rural human–environment system was mainly controlled by the per capita effective irrigation area(22.31%) and the per capita number of livestock(23.47%) from 1990 to 2000, the desertified area(25.06%) and the land use intensity(21.27%) from 2000 to 2005, and the per capita income of farmers and herdsmen(20.08%) and the per capita number of livestock(18.52%) from 2010 to 2007.(4) Under the effects of climate change and policy interventions, the cyclic adaptation of the rural human–environment system was propelled by the interactions between two kinds of subjects: farmers and herdsmen on the one hand and rural communities on the other hand. The interaction affects the adaptive behavior of the two kinds of subjects, which in turn drives the cyclic evolution of the system. As a result, the system structure and functions developed alternatively between coordinated and uncoordinated states. Small-scale adaptive behaviors of farmers and herdsmen have a profound impact on the evolution of the rural human–environment system. 相似文献
20.
The monthly, seasonal, and annual precipitation trends in the Yangtze river catchment have been detected through analysis of 51 meteorological stations' data between 1950-2002 provided by National Meteorological Administration. Results reveal that: 1) Summer precipitation in the Yangtze river catchment shows significant increasing tendency. The Poyanghu lake basin, Dongtinghu lake basin and Taihu lake basin in the middle and lower reaches are the places showing significant positive trends. Summer precipitation in the middle and lower reaches experienced an abrupt change in the year 1992; 2) The monthly precipitation in months just adjoining to summer shows decreasing tendency in the Yangtze river catchment. The upper and middle reaches in Jialingjiang river basin and Hanshui river basin are the places showing significant negative trends; 3) Extreme precipitation events show an increasing tendency in most places, especially in the middle and lower reaches of the Yangtze river catchment. 相似文献