Changing patterns of population distribution in Zimbabwe

This paper critically evaluates the causes and consequences of changes in population distribution in Zimbabwe during the colonial period and since independence in 1980. Five main aspects of population geography are examined. Firstly, by way on background on contemporary patterns of settlement and land use, the history of tenure policies is outlined. Secondly, the distribution of the African population as revealed in the 1982 census is described and major changes between the census years of 1962, 1969 and 1982 are discussed. Thirdly, changing patterns of settlement and land use within the peasant farming areas (Communal Lands) are examined in the context of increasing population pressures. Fourthly, trends in the growth of the main urban centres and the process of urbanisation of the African population are described. Fifthly, post-independence development policies directed at effecting changes in the distribution of population are discussed with particular reference to the land resettlement programme. The present distribution of population is seen as the product of interacting political, economic and environmental factors, knowledge of which is essential in devising appropriate development strategies to achieve a more equable balance of population and resources.     

Biomass estimation using Landsat-TM and -ETM+. Towards a regional model for Southern Africa?

Grazing and fire are major factors influencing the savanna ecosystems of Southern Africa. In both grazing and conservation areas overgrazing is an important reason for degradation of vegetation and soil. Insufficient fire management can cause a change in the species composition and may influence the soil negatively. For adequate planning purposes the knowledge of available biomass is indispensable. High-resolution satellite systems can provide such knowledge on a large scale. Three study areas in Southern Africa contributed to a first survey. Gutu District is situated in Zimbabwe. In its Communal Lands a high population density leads to severe degradation of vegetation and soil. The South African test sites are located in Kruger National Park and Madikwe Game Reserve. Therefore a wide ecological range from highly degraded to slightly disturbed savanna ecosystems is included. Satellite images of both Landsat-5 (TM) and Landsat-7 (ETM+) were applied. After cross-calibration of the two different satellite systems, indices applied to radiance and reflectance showed significant correlations with ground truth data of grass and other foliage biomass. Including new data from Hluhluwe National Park (South Africa) into the regression models improved the results, indicating that a regional model for savanna ecosystems in Southern Africa could be found. This revised version was published online in August 2006 with corrections to the Cover Date.     

Exile and exclusion: The legacy of soviet forestry for villages in the north of Perm oblast

This paper explores the relationship between the forestry enterprises (leskhozi) and the inhabitants of forestry villages in the northern rayony of Perm oblast, Russian Federation in the context of the `new regional geography'. These relationships are compared with those identified between peasant farmers and collective and state farms post-1991, and a theory of the cultivation of these relationships as a coping mechanism for both households and enterprises facing difficult economic circumstances is advanced. The situation in the northern rayony is contextualised through discussion of the settlement and development history of the region, which was a recipient of forced and voluntary labour migration during the Soviet period. The paper concludes that in accordance with recent theories of post-communist regional development, the experience of transition in the northern rayony of Perm oblast is determined at least in part by its social and economic context. This revised version was published online in July 2006 with corrections to the Cover Date.     

五十年代以来毛乌素沙地荒漠化扩展及其原因

本文在毛乌素沙地景观分类、制图及景观动态研究的基础上,分析了50年代以来毛乌素沙地荒漠化发展状况及其时空特征,并对其扩展原因进行了分析和探讨。结果表明,50年代以来,该地区荒漠化整体上处于迅速扩展之中,只是某些局部地方植被得到一定程度的恢复;荒漠化扩展存在明显的空间和时间差异：西北部纯牧区扩展速度远远高于东部和南部半农半牧地区,70年代末至90年代初扩展速度远远低于50年代末至70年代末;荒漠化的迅速扩展主要是由于不合理的人类活动造成的,气候波动也有一定影响。     

Sediment transfer in an extremely low-gradient,low-relief and highly buffered system: Darwin Harbour catchment,northern Australia

Abstract

Sediment yields from and sediment transfer within catchments of very low relief and gradient, which make up about 50% of Earth’s surface, are poorly documented and their internal sediment dynamics are poorly known. Sediment sources, their proportionate contributions to valley floors and sediment yield, and storage are estimated using fallout radionuclides ²¹⁰Pb_(ex) and ¹³⁷Cs in the catchments that drain into Darwin Harbour, northern Australia, an example of this understudied catchment type that appears to be globally at the extreme end of this category of catchments. Unchannelled grassy valley floors (dambos, or seasonal wetlands) trap ～90% of the sediment delivered from hillslopes by sheet and rill erosion. Further down valley, small channels transport ～10% of the sediment that escapes from the dambos, and the remaining sediment comes from erosion of the channels. In this case, the fractional sediment storage is very high as a result of the existence of dambos, a landform that depends for its existence on low gradients.     

Cultural land use and vegetation dynamics in the uplands of northern Portugal from the Middle Ages to the Modern period

In Europe, mountain landscapes have evolved in a long-term relationship with human communities and present-day landscapes reflect that ancient interaction. The present study aims to reconstruct human activity in two mountain areas in northern Portugal using palynological analysis integrated with the available regional historical, archaeological and palaeoenvironmental archives. Pollen records from two sedimentary sequences span the Medieval and Modern periods and show that mixed agriculture and livestock grazing were consistently present in both regions throughout these times. Variations in cultural indicators show that the extent of farming fluctuated throughout time, with a general increase in cultivation during the Medieval period but with contractions likely coinciding with times of social disturbance. Historical sources suggest that sociopolitical factors and population pressure were fundamental in the utilisation of upland spaces. This study did not find any convincing evidence to suggest that fire was a fundamental factor in heathland spread. We conclude that long-term occupation of the uplands was sustained by low-intensity land use throughout the Medieval to post-Medieval periods, and that the present landscape has assumed a very different character following depopulation of the mountain areas and a shift towards commercial forestry.     

Ecological problems arising from intensive agriculture in Western Slovakia

In Slovakia in the second half of the twentieth century, agriculture gradually changed from a private peasant to a socialist type, with the aim of achieving a large scale of production. But the switch from ownership to user rights disturbed the peasants' sensitive attitude towards the land which had evolved through the ages. Agriculture uses 65 percent of the land in Western Slovakia which is the most important part of the country for farm production. Intensive farming involves constant anthropic pressure and in consequence there is much erosion and soil contamination. As an example, this essay investigates eleven districts which form part of the West Slovakian region. An attempt is made to evaluate new trends in the development of regional agricultural structures in agriculture from the environmental point of view.     

Patterns of gullying in Zimbabwe

In Zimbabwe four contrasting gully locations and associated gully patterns are present, reflecting spatial variations in precipitation, bedrock, soil type and landuse. Deep dendritic gullies, associated with landslip activity and subsurface piping, characterise the wet Eastern Highlands and areas with sodic soils. Shallow discontinuous gully systems characterise bornhardt terrain in the Communal Lands. Dambo gullies tend to form a continuation of the fluvial system. The pattern and temporal variation of gullies was studied in three areas of Communal Land (Mhondoro-Ngesi, Mangewende, Mutema) with particular reference to the influence of average slope and landuse on gully development. In areas of sodic soils the gullies appear to be largely the product of natural processes and their development has only partly been influenced by landuse changes. In contrast the shallow gullies developed on granitic/gneissic terrain tend to occur on cultivated or recently cultivated land. The case studies indicate that a full assessment of gully development can only be achieved if a temporal perspective is also considered.     

SD法在湖北大冶鸡冠嘴铜金矿床资源储量核实中的应用

SD法是一种全新的储量计算和审定方法,是我国使用的三大储量计算方法(传统法、克里格法和SD法)之一.根据国土资源部的指示和要求,湖北三鑫金铜股份有限公司和北京恩地科技发展有限责任公司共同对矿区的13条勘探线、20个矿体、16个中段的资源储量运用SD法进行了全面的复核计算,成功地确定了鸡冠嘴铜金矿矿床-160～-170 m、-170～-470 m、-470 m以下铜和金的保有储量.     

A rural development strategy for the Apuseni Mountains, Romania

The Apuseni Mountains, part of the Western Carpathians, are distinctive in cultural terms because of the highly dispersed settlement patterns that have developed on the high erosion surfaces where the Moti people cleared the forests to allow for an expansion of family farming in the eighteenth and nineteenth centuries. These small ‘crang’ settlements remain, but the population is declining in the face of limited employment opportunities and poor services. The question arises as to the most appropriate rural development strategy for the region, following the communist period which encouraged centralisation through the provision of housing and industry in key villages and new towns. The emphasis on private farming and the expansion of tourism could protect the inherited cultural landscape but money must be found to improve rural services. There is also a strong conservation movement which supports the establishment of a national park, but this could constrain development through controls on grazing and woodcutting. Hence the dialogue continues to find the best compromise and the concept of a ‘natural park’ is being discussed with such a reconciliation in mind. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigating spatial contribution of land use types and land slope classes on soil erosion distribution under tropical environment

Natural Hazards - Increasing land occupancy for farming without conservation principles, particularly in the Indonesian island of Java, is resulting in a severe erosion problem. This study...     

不同放牧方式对岩溶区土壤养分的影响 ——以广西桂林岩溶区实验基地为例

根据实验数据,探讨了不同放牧方式对岩溶区土壤的肥力、微量元素含量、水涵养性等的影响。结果表明,在正常放牧的情况下,能迅速提高牧草区土壤的养分和水的涵养性,减少水土流失,灌木种植初期不宜进行放牧;而在人为破坏和过度放牧的情况下,可在短期内导致岩溶区生态环境向着恶化的方向演替,土壤养分的各项指标下降到甚至低于未修复前的状态。     

Environmental impacts of shrimp farming with special reference to the situation in the continental United States

Shrimp culture technology has resulted in development of a major shrimp farming industry worldwide. Without the shrimp farming industry, increasing demands for shrimp by consumers could not be met, resulting in increased pressure on wild shrimp resources. Unfortunately, there are realized and potential adverse environmental effects on estuarine ecosystems as a result of shrimp farming. The effects can be categorized as wetland destruction for construction of shrimp farms, hypernutrification of estuarine ecosystems by shrim pond effluent, “biological pollution” of native shrimp stocks through escapement of aquaculture stocks, water use and entrainment of estuarine biota, and impacts of shrimp farm chemicals on estuarine systems. While the shrimp farming industry in the United States is small, the United States is effectively addressing all the realized and potential environmental impacts through regulation and research at the federal and state levels. Areas of regulation and research include stringent prohibitions on wetland destruction, regulation of effluents and support of research to eliminate and/or reduce effluents, escapement prevention technology and development of high-health stocks, minimizing entrainment of estuarine biota through water conservation and screening technology, and regulation of chemical use in the shrimp farming industry and support of research on shrimp pathology and environmentally safe disease control. Work is still in progress and not all problems have been resolved to the complete satisfaction of shrimp farmers and estuarine conservationists. However, the situation in the United States should serve as a model of how to encourage sustainable economic development through commercial shrimp farming while abating adverse environmental impacts on estuarine systems. To further improve the situation, the development and adoption of “best management practices” for shrimp aquaculture are recommended.     

Assessing the role of winter grazing in historic land degradation,Mývatnssveit,northeast Iceland

This paper assesses the contribution of historical and traditional winter grazing to long‐term land degradation in northeast Iceland. To do so, indicators of soil erosion from two contrasting historical winter grazing areas, set in a tephrochronological framework, are compared against their temporal and regional land degradation contexts. The observations made indicate distinctive and different landscape responses to historical winter grazing depending on location. In both study areas, there is an accelerated level of wind and water erosion with settlement at ca. A.D. 874 through to A.D. 1477. One of these areas had a subsequent reduction in erosion rates to considerably below the regional average, possibly as a result of adaptive land management; the second, more inherently sensitive area, is now subarctic desert. These findings confirm early land management practices as a major factor in Icelandic land degradation, they contribute to explanations of early settlement success and failure, and highlight the significance of historical approaches in addressing contemporary issues of land degradation and conservation responses. © 2004 Wiley Periodicals, Inc.     

The ethno-environmental fix and its limits: Indigenous land titling and the production of not-quite-neoliberal natures in Bolivia

During the 1980s and 1990s, an era of neoliberal reform, global development institutions like the World Bank began promoting and financing the collective titling of indigenous territories. Extending and linking existing discussions of neoliberal multiculturalism and neoliberal natures, this paper interrogates indigenous land rights as a type of “ethno-environmental fix”, designed to synergise protection of vulnerable populations and highly-valued natures from the destructive effects of markets, in an era of multiple countermovements. Using the example of the titling of TCOs (Original Communal Lands) in Bolivia, the paper explores how governmental aspirations for indigenous territories unravelled in practice, producing hybrid, double-edged and “not-quite-neoliberal” spaces – spaces which have, paradoxically, emerged as key sites for the construction of more radical indigenous projects.     

Human impact on the karst of the Venetian Fore-Alps, Italy

People have been exploiting the limestone massifs of the Venetian Fore-Alps since prehistory. The fluviokarstic style of the relief and the location of springs were important controls of settlement and land use. Six principal types of exploitation are recognized and overlapped in time: (1) hunting and early farming, Paleolithic to Iron Age, with the first soil erosion; (2) general deforestation for timber, charcoal, and fuel, Roman to early modern; (3) farm enclosure and improvement, with stone clearing, medieval to modern; (4) trench warfare in World War I; (5) quarrying and specialized farming (dairy, poultry, pigs) since 1950; and (6) developmnent of modern summer and winter tourist facilities. Soil erosion effects from many centuries can still be recognized, war damage remains visible and continues to pollute aquifers, and modern pressure on the karst land and water resources is often severe.     

我国北方农牧交错带的环境演变

中国北方农牧交错带在１０～８．５ｋａＢ．Ｐ．经历了三次阶段性增暖后进入全新世暖期。８．５～８．０ｋａＢ．Ｐ．和４～３．５ｋａＢ．Ｐ．暖期的开始与结束事件中降水变化落后于温度变化３００～５００ａ；暖期盛期时的年均温较现代高２～３℃，降水多１００ｍｍ左右；暖期中存在多次短期寒冷事件，年均温最冷时较现代低３℃以上。３．５ｋａＢ．Ｐ．以来冷干趋势之上叠加着大致由３００ａ稳定与５００ａ波动构成的约８００ａ的周期性变化。全新世暖期原始农业文化的阶段性发展与暖期内环境波动相对应；暖期结束时发生了由农业向牧业文化转换的事件；暖期以后的冷干期为农牧交错文化时期，农业经济随冷干程度的变化而兴衰     

基于GIS重庆岩溶地区生态环境脆弱度评价

重庆岩溶区属典型的生态环境脆弱区,宜耕地资源不足,土地退化严重,承受自然灾害能力低,使岩溶地区的社会经济发展和生态环境的协调性差,可持续发展能力弱。本文以重庆市岩溶地区为例,选择碳酸盐岩出露面积、山地面积、旱坡耕地面积、石漠化程度(包括轻度、中度和高度)、森林覆盖率、水土流失面积、土壤侵蚀模数、滑坡体积密度、垦殖指数、人均耕地面积、农业人口密度等13项生态环境脆弱度影响因子作为评价指标,利用层次分析法赋予指标权重,然后构建模糊数学模型对岩溶地区生态环境脆弱度进行评价研究,基于GIS技术对评价结果进行等级划分。结果表明: 重庆25个岩溶区县中潜在脆弱区县3个,轻度脆弱区县10个,中度脆弱区县6个,重度脆弱区县6个。      

Climate, agriculture, and cycles of human occupation over the last 4000 yr in southern Zacatecas, Mexico

Scholars attribute the growth and decline of Classic period (AD 200-900) settlements in the semi-arid northern frontier zone of Mesoamerica to rainfall cycles that controlled the extent of arable land. However, there is little empirical evidence to support this claim. We present phytolith, organic carbon, and magnetic susceptibility analyses of a 4000-yr alluvial record of climate and human land use from the Malpaso Valley, the site of one such Classic frontier community. The earliest farming occupation is detected around 500 BC and appears related to a slight increase of aridity, similar to the level of the modern day valley. By AD 500, the valley's Classic period Mesoamerican settlements were founded under these same dry conditions, which continued into the Postclassic period. This indicates that the La Quemada occupation did not develop during a period of increased rainfall, but rather an arid phase. The most dramatic changes detected in the valley resulted from the erosion associated with Spanish Colonial grazing and deforestation that began in the 16th century. The landscape of the modern Malpaso Valley is thus primarily the product of a series of intense and rapid transformations that were concentrated within the last 400 yr.     

The impact of agronomic inputs on selected physicochemical features and their relationships with heavy metals levels in surface sediment and water in sugarcane farms in Nzoia,Kenya

Sugarcane farming is the most important cash crop cultivation activity in the Lake Victoria basin of Kenya practised in an area covering approximately 114,000 Ha in total. For better yields, various agronomic inputs including fertilizers and herbicides have been used intensively in the farms, causing serious concerns about their potential impacts on the aquatic ecosystems within the lake basin. In this study, the physicochemical features of surface sediment and water including pH, total organic carbon contents and heavy metal (Cd, Cu, Zn, Pb and Cr) loads in River Kuywa and in runoff canals in sugarcane farms in Nzoia nucleus estate within the lake basin were determined to assess the effects of agronomic activities including agronomic inputs in the form of nitrogenous fertilizers [urea and diammonium phosphate (DAP)], herbicides and sewage sludge used in farming on their levels. The results indicated significant differences (p ≤ 0.05) in the heavy metal levels in sediment and water samples taken before and after the farms, respectively, indicating a positive impact on the concentration levels. The canal water and sediment samples’ heavy metal levels were also significantly higher than those of the river samples showing that the influent sugarcane farm canal waters transfer these contaminants into River Kuywa. Although the levels of these parameters were significantly higher in the canals than in the controls obtained from outside the sugarcane farms, the heavy metal levels in soil samples from within the farms with similar agronomic activities did not differ significantly among the various plots. The turbidity, electrical conductivity, temperature, water and soil pH and total organic carbon values in samples obtained within the sugarcane farms showed significant seasonal variations and differed significantly from the values in the controls showing a significant negative impact of agronomic inputs on water quality.