Le système régional d'action éolienne (SRAE) du bassin de l'Aral (Kazakhstan,Ouzbékistan et Turkménistan)The regional Aeolian action system of the Aral Basin

The endorheic basin of the Aral Sea, a tectonic depression resulting from two Tertiary fault bundles, NNE–SSW and east–west ones, represents the termination of a flow by closure of the Aral Basin opposite Central Asia and Siberia. The conditions of Quaternary climate and sediment deposition, especially aridity increased by coldness, a pedogenesis inhibitor, and absence of palaeosoils favour the activity of the Aralian Regional Aeolian Action System (RAAS), 700 km long. Such a system develops in a lowland topography where wind, in a progressive shift, reconstructs by deflation the sandy material resulting from Pleistocene accumulations, gives rise to thin and vulnerable ergs and explains at once the fertility of Khoresm and the dewatering of the Aral Sea, which is one of the most complex and severe ecological catastrophe in the 20th century. To cite this article: M. Mainguet et al., C. R. Geoscience 334 (2002) 475–480.     

中国北方地区沙漠与河流景观格局

本文运用景观生态学原理,借助ArcGIS技术,选择中国北方10个流域及其12个沙漠/沙地,并以西部的和田河和东部的西辽河为典型研究区,在流域与沙区、河道与沙丘两个尺度上,选取景观破碎度指数、景观多样性指数等指标,探讨中国北方干旱、半干旱区沙漠/沙地景观与廊道景观(河流)的空间镶嵌格局特征。结果表明：在流域与沙区尺度上,内流区较外流区沙区景观类型复杂,景观破碎度较小,外流区沙区景观结构较为相似;内流区沙区景观指数自西向东呈现出“景观破碎度递增、景观结构复杂性递减”的规律。在河道与沙丘尺度上,在缓冲带范围内,和田河较西辽河沙丘景观类型复杂,景观破碎度较小;景观指数随河道距离的变化呈现出“景观破碎度随距河道距离的加大而逐渐递减,丰富度指数随距河道距离的加大而呈阶梯状递增”的规律;从沙丘斑块类型景观指数上看,西辽河以固定、半固定的简单型沙丘为主,和田河以流动的综合型沙丘为主。主导的沙丘类型景观距离河道越远,面积比例越小,不同沙丘类型的水平景观破碎度随河道距离递减。     

科尔沁沙地近50年的垦殖与土地利用变化

放牧和垦殖是我国北方农牧交错带主要土地利用活动。该活动范围的扩大或缩小、活动强度的增大或减弱是引起交错带土地利用变化的直接因素 ,其结果是草地和耕地面积的量变和质变 ,也是该区土地利用变化最直观的体现。文章选取我国典型的农牧交错区——科尔沁沙地 ,以人类垦殖活动作为主线 ,以耕地面积变化作为切入点 ,对科尔沁沙地近 50年的土地利用变化进行了动态分析。结果表明 :随着建国以来四次大规模的垦荒 ,科尔沁土地利用格局产生了显著的变化 ,集中体现为耕地面积的大幅度增加和草地等其他用地面积的减少 ,具体表现则是沙地农耕北界的北跃和耕地重心的北移。文章进而分析了引起这一变化的主要人文因子。     

The Pattern of General Atmospheric Circulation in Eastern Asia Before the Uplift of the Tibetan Plateau

THE PATTERN OF GENERAL ATMOSPHERIC CIRCULATION IN EASTERN ASIA BEFORE THE UPLIFT OF THE TIBETAN PLATEAU     

Characterization and Temporal Variation of Asian Dust Aerosol from a Site in the Northern Chinese Deserts

Time series for total aerosol mass and the concentrations of nineteen elements, and the mass particle-size distributions of the elements, were determined for samples collected from a site in the northern deserts of China -Zhenbeitai, one of ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). Nine dust storm (DS) events were observed during the spring of 2001, lasting a combined total of twenty-six days. Peak mass loadings greatly exceeded the average (260 g m^–3), and higher than average dust-element concentrations and wind speeds were also observed during the three-month study. Material balance calculations showed that 82% mass of the total aerosol particles could be ascribed to Asian dust, of which Al, Ca, Fe, K, Mn, Si and Ti accounted for 7%, 6%, 4%, 2%, 0.1%, 32% and 1% by weight, respectively. Modelcalculated dry deposition velocities for 7 dust-elements during dust storm periods averaged 17 cm s^–1 and ranged from 14 to 21 cm s^–1. The estimated dry depositiona of Asian dust for the spring of 2001 was 189 g m^–2, of which 85% was due to dust storms. Factor analysis indicated that 89% of the dust loading during this period was due to remote or regional transport; 11% to local or background dust.     

A fresh framework for the ecology of arid Australia

A revised set of propositions about ecology in arid Australia is presented, based on research literature since publication of Stafford Smith and Morton (1990). Fourteen propositions distil our argument that most features of the Australian deserts are explicable in terms of two dominant physical and climatic elements: rainfall variability, leading to extended droughts and occasional flooding rains; and widespread nutrient poverty. Different landscapes within the arid zone show these features to varying degrees, and so it is important to think about different places separately when considering our propositions. Plant life-histories strongly reflect temporal patterns of soil moisture; because Australian deserts receive more variable rainfall than most others, there is a distinctive spectrum of life-histories. Low levels of phosphorus (together with abundant soil moisture on irregular occasions) favour plants producing a relative excess of carbohydrate (C). In turn, C-rich plant products sometimes lead to fire-prone ecosystems, assemblages dominated by consumers of sap and other C-based products, and abundant detritivores (particularly termites). Fluctuations in production due to variable rainfall provide openings for consumers with opportunistic life-histories, including inhabitants of extensive but ephemeral rivers and lakes. Most consumer species exhibit some dietary flexibility or utilise more dependable resources; these strategies give rise to greater stability in species dynamics and composition of assemblages than might first be imagined under the variable rainfall regime. Aboriginal people have had long-standing ecological influence as they accessed resources. For each proposition we suggest the extent to which it is ‘different’, ‘accentuated’ or ‘universal’ in comparison with other deserts of the world, recognising that this categorisation is in need of critical testing. Further tests of each proposition are also suggested to fill the many gaps that still exist in our knowledge of the structure and functioning of Australia’s deserts.     

Ant assemblages at their dry limits: the northern Atacama Desert, Peru, and the Chott El Djerid, Tunisia

Ants do not occur in the rocky desert of the Nazca Plain, Peru, except in the vicinity of shrubs in outwash gulleys, where there are two species that have similar activity periods and microhabitats and exhibit interference competition. Only one species of ant was found on the Chott El Djerid, Tunisia, a large, dry salt lake, devoid of vegetation.     

THE ORAL HISTORY OF GEOGRAPHY∗

Book Reviewed in this article:

Latin America: Case Studies. Richard G. Boehm and Sent Visser

Locality and Rurality: Economy and Society in Rural Regions. Tony Bradley And Philip Lowe

The City and the Grassroots. Manuel Castells

Geopolitics and Conflict in South America. Quarrels among Neighbors. Jack Child

Post-Industrial America: A Geographical Perspective. David Clark

Coastal Research: UK Perspectives. Malcolm W. Clark

A Rural Policy for the EEC? Hugh Clout

Peasant Agriculture in Assam: A Structural Analysis. M. M. Das.

Environmental Change and Tropical Geomorphology. I. Douglas and T. Spencer

Advances in Abandoned Settlement Analysis: Application to Prehistoric Anthrosols in Colombia, South America. Robert C. Eidt

Measuring Culture. Jonathan L. Gross and Steve Rayner

North America: A Human Geography. Paul Guinness and Michael Bradshaw

A Geographical Bibliography for American Libraries. Chauncy D. Harris et al.

Geography and the Urban Environment: Progress in Research and Applications, Vol. VI. D. T. Herbert and R. J. Johnston

Changes in Global Climate: A Study of the Effect of Radiation and Other Factors During the Present Century. K. Ya. Kondrat'ev.

Rural Development and the State: Contradictions and Dilemmas in Developing Countries. David A. M. Lea and D. P. Chaudhri

The Martial Metropolis: U.S. Cities in War and Peace. Roger W. Lotchin

The Climate of the Earth. Paul E. Lydolph.

Weather and Climate. Paul E. Lydolph.

Spatial Divisions of Labor: Social Structures and the Geography of Production. Doreen Massey.

Panorama of the Soviet Union. N. Mikhailov.

Soviet Armenia. K. S. Demirchian.

USSR: Geography of the Eleventh Five-Year Plan Period. K. Spidchenko.

Planung und Verwirklichung der Wiener Ringstrassenzone (Planning and Materialization of the Ringstrasse-Zone of Vienna). Kurt Mollik, Hermann Reining, Rudolf Wurzer.

The American West Transformed: The Impact of the Second World War Gerald D. Nash.

An Overview of the Survey of Income and Program Participation. Dawn Nelson, David McMillen, and Daniel Kasprzyk.

Phenomenology, Science and Geography: Spatiality and the Human Sciences. John Pickles.

Biological Diversification in the Tropics. Ghillean T. Prance

Die Wanderviehwirtschaft im gebirgigen Westen der U.S.A. und ihre Auswirkungen im Naturraum. Gisbert Rinschede.

Social and Economic Aspects of Radioactive Waste Disposal: Considerations for Institutional Management

World-Wide Weather. K. Takahashi

Coastal Geomorphology in Australia. B. G. Thom

Settlement System in Rural India: A Case Study of the Lower Ganga-Yamuna Doab. Ram Chandra Tiwari.

Computer Programming for Geographers. David J. Unwin and John A. Dawson.

Late Quaternary Environments of the Soviet Union. A. A. Velichko, ed. H. E. Wright, Jr. and C. W. Barnosky

Ethics in Planning. Martin Wachs     

Access to supermarkets among poorer neighborhoods: a comparison of time and distance measures

This research assesses neighborhood differences in access to supermarkets for the Portland, Oregon region. Five-year American Community Survey data for the 2006–2010 period are used to compare a travel time and distance measure of supermarket access for neighborhoods of concentrated poverty relative to other neighborhoods, taking into account their distance to the city center. Poor and nonpoor outer neighborhoods have longer average travel times and distances to nearby supermarkets than their more centralized counterparts. Poor outer neighborhoods fare better on travel distance than nonpoor outer neighborhoods do, but endure penalties in longer travel times. This research demonstrates the potential for variation in results across methods measuring access to neighborhood amenities and suggests that more nuanced methodology will be required for us to understand sociospatial disparities in access.     

中国现代沙漠动态变化及其发展趋势

用遥感、地图和野外考察研究等方法,首次揭示了我国现代沙漠动态变化规律和发展趋势,认为我国现代沙漠动态变化的总趋势是向草原化和绿洲化方向缓慢发展,其变化速度为４４５ｋｍ２／ａ,我国现代沙漠还在继续蔓延,但其扩大速度比较缓慢,约为３１０ｋｍ２／ａ。