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1.
The forests of southeastern Africa are vulnerable to damage imposed by tropical cyclones operating in the South Indian Ocean. We undertook a geographical analysis to determine the relative vulnerability of forests given tropical cyclones recorded during the 1959–2008 storm seasons. From this analysis, eastern coastal forests of Madagascar seem to be the most vulnerable, although return intervals for severe storms vary along the eastern coast, and are shorter (about 10 years) through the central portion of the country. Therefore, the central lowland to upper montane rainforests on the eastern coast seem to be more vulnerable to damage from tropical cyclones than others in the area. While not as extensive, western coastal forests of Madagascar are also as vulnerable in part due to the recurvature of storms in the Mozambique Channel. Though the coastal forests of Mozambique are all nearly equal in terms of vulnerability, the return interval for severe storms to this area is highly variable. The inland Miombo forests of southeast Africa are less vulnerable to damage from tropical cyclones; however, portions of western Mozambique and Zimbabwe have experienced strong tropical storms in the last 50 years. A number of caveats and limitations associated with the data and analyses are noted. Given the broad scale of the study, the relative vulnerability and the return intervals for severe storms should be considered general representations of these phenomena for the southeastern African coast and the island of Madagascar. 相似文献
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Vishwambhar Prasad Sati 《Singapore journal of tropical geography》2008,29(2):173-185
This paper looks at the key resource interactions driving the current trend in intramontane mobility as a traditional subsistence practice in the Garhwal Himalaya region of Uttaranchal, India. For hundreds of years, the natural resource based mid-altitude villages in the Pindar River basin hinged on the annual summer migration to highland pastures. Where self-sufficiency has been obtained through an environmentally embedded tradition of crop and livestock farming, highland forests and alpine pastures continue to provide the human and animal requirements of fuelwood and fodder, as well as the forest products defining traditional diets and cottage industry. The paper reports the data from a rapid appraisal survey of resources obtained by households in selected mid-altitude villages from the seven highland locations that have sustained the centuries-old subsistence culture of the Pindar basin. While livestock have been the crucial link in a forest/fodder–manure–cultivation chain that has necessitated households' dependence on highland pastures and forests, over the last four decades there has been a decline in the numbers engaged in livestock raising and, concomitantly, the annual migration to summer pastures. Instead, there is a trend towards increased cultivation of cash crops and forest resource collection in the traditional highland encampment areas. 相似文献
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While habitat destruction always causes species extinctions, the rate of extinction may be highest in those habitats which become the most fragmented as they decline in size. For this reason, knowledge about the patterns and origins of rain forest fragmentation in the tropics may prove useful in efforts to preserve biodiversity. This paper calculates the degree of fragmentation in the tropical rain forests of 51 nations containing 83 per cent of the world's tropical forests. By these measures, West Africa and Central America have the most fragmented tropical rain forests in the world. Not surprisingly, rain forests in the Amazon basin are the world's least fragmented. Some patterns of tropical deforestation appear to produce more fragmentation than others. A two-stage least squares analysis of these data suggest that deforestation driven by smallholders is most likely to produce highly fragmented forest habitats. The implications of these findings for policy and for further research are briefly discussed. 相似文献
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Michael O'Neal Campbell 《Singapore journal of tropical geography》2005,26(2):151-169
Despite recent interest in sacred (fetish) groves as remnant forests, few studies have investigated their sustainability and conservation role in West Africa. This article employs a Geographical Information Systems (GIS) analysis of time series images (1960‐98), comprehensive social surveys and ecological field methods to evaluate four sacred groves and eight unprotected tree stands in the coastal savanna of Ghana and compare these with vegetation in the distant forested hinterland. There were strong similarities and substantial differences in tree species between different sacred groves, and between these and the unprotected stands and proximate deciduous forests. In addition, far fewer tree losses were documented in the sacred groves than in the local unprotected stands. Although these sacred groves were on average only partially representative of deciduous forest vegetation, their stronger sustainability compared with unprotected tree stands may be important to consider in detail for conservation. 相似文献
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Paul Claval 《Singapore journal of tropical geography》2005,26(3):289-303
This article broadly positions the successful establishment of the field of French tropical geography in the immediate postwar period against developments stemming from a longer history of French colonial engagement in Africa, Asia and South America, and clarifies the seemingly late timing of, and paradoxes involved in, the creation of a body of French scientific knowledge about the tropics. Colonial scientific research did not develop in France until the end of the nineteenth century. However, the colonial geography appearing at this time did not rely on fieldwork but, rather, catered to the demands of the business class for overseas expansion and to public curiosity. Even while the medical geography of tropical areas and knowledge of tropical soils and ecology progressed greatly between 1900 and 1940, there were still only a few French geographers working in the tropics. With the advent of the Second World War, when “big science” appeared in France and its colonial empire, the number of French geographers involved in tropical research grew rapidly. The field of tropical geography built up by Pierre Gourou was a synthesis of approaches developed in South America, Africa and Indochina. Although it soon came under strong criticism for its pessimistic view of prospects for industrialisation and urbanisation in the tropics, it seduced French geographers because it matched the contemporary interest in zonality and relied on a genre de vie analysis of, typically, rural areas. Thus, the postwar blossoming of tropical geography shaped by Gourou was more a response to various internal dynamics within French geography than an exercise in imperialism. Its demise was not due to the eclipse of French colonialism but, rather, its inability to deal with the modernisation of tropical societies. 相似文献
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非洲外商直接投资的时空变化与影响因素 总被引：1，自引：0，他引：1
基于2006—2017年非洲52个国家FDI数据以及其经济、政治、资源等数据，运用泰尔指数和面板数据固定效应模型对非洲外商直接投资的时空变化与影响因素进行研究。研究结果表明：1）非洲FDI流入量整体呈现出波动上升的趋势，其中北非呈现下降趋势，西非和中非呈现出波动上升的趋势，东非的上升趋势相对稳定且强势，南部非洲地区波动变化显著，趋势不明显；随着非洲经济发展，五大区域中北非和西非的FDI流入量最多，呈现出“两强三弱”的区域分布格局。2）非洲FDI总体差异呈现出缓慢上升趋势，年际变化呈现出“减—增—减”的波动；影响FDI总体差异的主要因素是区域内部差异，西非、南部非洲和中非区域内部的差异尤为明显，其中西非内部差异贡献最大。3）经济社会环境因素整体上对非洲FDI影响有限，但局部对西非影响较大；经济发展水平对东非、南非的外资流入起着积极作用，而对西非起着抑制作用；对外开放度对西非起着消极影响；聚集效应对西非、中非、北非的作用有限。政治制度因素整体上对非洲外资具有显著的作用，但局部对北非和东非作用有限。资源禀赋因素总体上是外企对非洲区位选择的决定性因素，但局部对北非和东非影响不大。基础设施因素总体上对非洲大陆FDI的流入量影响不大，但对南部非洲地区除外。 相似文献
7.
岷江上游大沟流域油松人工幼林生物量组成及其影响因素 总被引：2，自引：1，他引：2
为了揭示人工林不同层次的生物量组成关系及其影响因素,选择岷江上游大沟流域的油松人工林,调查分析了林分不同层次生物量组成及其关系,探讨了乔木密度、坡向、海拔对生物量的影响。发现:1)两种林龄油松人工林生物量分配基本一致,即,乔木层>灌木层>草本层;乔木各构件生物量大小顺序为:枝>干>叶>根>果/皮。同时指出,枝叶对下木层生物量的影响显著。2)乔木密度显著控制了林分生物量及其组成,在本调查范围内坡向的影响似乎不明显;海拔对22 a油松影响显著,而24 a的不显著;综合分析表明,本区域内,22 a油松保持在3 800株/hm2左右和24 a在3 500株/hm2左右时,有助于林分生物量的稳定与提高,促进生态系统功能的恢复。 相似文献
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Wikitoria August 《New Zealand geographer》2005,61(2):117-123
Abstract: This article examines Māori women and the ways in which their bodies are constituted within particular cultural spaces, namely at urupā and sites where food is gathered. Māori bodily rituals, and the impacts of colonization on these bodily rituals, are explored to reveal a ‘nonwestern’ perspective on exclusion. Kaupapa Māori research and postcolonial theory have been combined to produce research that respects and nurtures Māori practices. Colonial notions of blood and menstruation, which inscribe women as ‘dirty’ and ‘unclean’, are critiqued. What is advocated is a Māori perspective that constructs Māori women as connected to Atua, and as powerful, sacred and life‐giving. 相似文献
11.
南非是中国在非洲的最大投资目的地与经贸合作伙伴, 特别在基础设施建设方面发展迅速。南非人口空间分布研究对开展中南合作具有重要意义。本文通过收集整理南非历年来的全国人口普查资料统计数据, 运用空间自相关模型、不均衡指数、人口重心模型和偏移—分享模型, 分析了南非人口的空间分布格局和演变特征。研究结果表明, 南非人口分布具有显著的“东高西低”的空间格局, 呈现出以工业化程度较高的大都市区和港口城市为中心的“多核心”集聚的分布特征;空间自相关分析得出人口高集聚区主要分布在大都市区和沿海港口城市, 低密度集聚区主要集中分布在中西部地区;从变化趋势上来看, 1996-2011 年间人口分布不平衡趋势不断加强, 人口重心向西北方向移动;偏移—分享分析表明, 南非人口增长速度先后经历了从1996-2001 年快速增长到2001-2007 年缓慢增长, 再到2007-2011 年高速增长的“高—低—高”增长阶段;省域层面上看, 豪登省和西开普省一直是南非人口集聚较强地区。 相似文献
12.
广西北仑河口红树林湿地大型底栖动物多样性的初步研究 总被引：1，自引：0，他引：1
2010年7月对广西北仑河口红树林湿地的大型底栖动物进行调查,共发现大型底栖动物8门10纲46科106种,其中软体动物49种,甲壳类36种,多毛类10种,其它类11种。生物量优势种和密度优势种都是软体动物门的珠带拟蟹守螺。大型底栖动物平均生物量是103.09g/m2,平均密度是196个/m2。与历史调查数据比较,本次调查发现了69种本地新种;对比国内6个红树林区底栖动物群落结构,其生物量及栖息密度属于中等偏下,物种多样性指数高于其它红树林区。结果表明:底栖动物的生物量及栖息密度与红树林发育状况呈负相关的关系,物种多样性与红树林发育状况呈正相关的关系。 相似文献
13.
Elhadi Adam Onisimo Mutanga Riyad Ismail 《International journal of geographical information science》2013,27(10):1924-1938
The cossid moth, Coryphodema tristis was first noted on Eucalyptus nitens trees in Mpumalanga province, South Africa during July 2004. Currently, the moth poses a major threat to commercial forestry in the country. In this study, selected climatic and topographical variables were used to model the susceptibility of E. nitens forests to cossid moth occurrence, thereby providing insight into the variables that may influence the occurrence and spread of the moth. A zigzag sampling technique was used to survey 5316 ha of E. nitens forests for the presence or absence of the moth. The random forest classification algorithm was then used to model the relationship between the climatic and topographical variables and the occurrence of the cossid moth. Results indicate that four variables that included elevation, maximum temperature for September, maximum temperature for April and the median rainfall for April best explained the presence or absence of C. tristis with an overall accuracy of 82% and a kappa value of 0.63. Partial dependence plots indicated that the areas that have a maximum temperature greater than 23°C in September and 22°C in April are likely to be infested by the cossid moth. The results from this study provide a robust and accurate spatial framework to assist forest managers in focussing their existing monitoring and control efforts to specific E. nitens forested areas that are highly susceptible to C. tristis infestations. 相似文献
14.
A. Ayari D. MoyaM.N. Rejeb A. Ben MansouraA. Albouchi J. De Las HerasT. Fezzani B. Henchi 《Journal of Arid Environments》2011,75(5):403-410
Aleppo pine (Pinus halepensis Mill.) is found in discontinuous bands along the Mediterranean Basin, usually at low elevations and in dry climates. This study was conducted to relate bioclimatic zones and geographic distribution with representative individual tree of populations for cone number and weight from the driest to the wettest Aleppo pine forest zones. Epidometric values were recorded in all sample stands in the monitoring plots set in 79 native populations from the Algerian border to the eastern coast of Tunisia, representing a wide range from each region in northern Africa. Simple and multiple regressions were performed on the data. Results showed that the canopy seed bank increased according to elevation, latitudinal and longitudinal gradients. The simple regression analysis showed a latitudinal effect positively relating increasing latitude to greater cone crop. Similarly, longitudinal and elevation variations were related to significant differences in cone dimensions. Higher average seed mass was related to populations located westwards or at higher elevation. The multiple regression analysis indicated that the longitudinal variations were the most determinant geo-positional factors in Aleppo pine cone dimensions and average seed mass in natural Aleppo pine forests in Tunisia. 相似文献
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Mangrove forests provide vital ecosystem services for millions of people living in coastal communities. The expansion of aquaculture production and urbanization have been identified as major causes of mangrove clearance in South-East Asia. The Ca Mau peninsula in Vietnam is leading the country in shrimp aquaculture and at the same time, the region is home to the largest remaining mangrove forests. This study aims to assess the spatial and temporal mangrove forest dynamics in Ngoc Hien district in Ca Mau. Land cover change and fragmentation are quantified using remote sensing imagery consisting of a series of SPOT5 scenes from 2004, 2009 and 2013. The results indicate a high turnover of land cover change, with close to half of the mangrove forests being affected by land cover changes between 2004 and 2014. Net changes in mangrove forest are found to average −0.34% annually, characterized by deforestation between 2004 and 2009 and afforestation of between 2009 and 2013. Fragmentation remains a plausible threat; approximately 35.4% of the mangrove forests in Ngoc Hien are part of interior ‘core’ forests. Forest zones with different regulation regimes play a significant role in shaping the geographic distribution of mangrove forest changes. The insights into recent mangrove forest dynamics facilitate the informed discussion on improving future protection of the mangrove forests abiding anthropogenic pressures. 相似文献
17.
20世纪80年代以来全球耕地变化的基本特征及空间格局 总被引：3，自引：0，他引：3
本文基于全球1982-2011年土地利用/覆被的矢量数据,分析了20世纪80年代以来全球耕地变化的基本特征及空间格局。结果表明：① 20世纪80年代以来,全球耕地面积增加了528.768×104 km2,增加速率为7.920×104 km2/a,呈不显著增加趋势,全球耕地面积以20世纪80年代增速最快。20世纪80年代以来,北美洲、南美洲、大洋洲耕地面积呈显著增加趋势,分别增加了170.854×104 km2、107.890×104 km2、186.492×104 km2,增加速率分别为7.236×104 km2/a、2.780×104 km2/a、3.758×104 km2/a;亚洲、欧洲、非洲耕地面积为减少趋势,分别减少了23.769×104 km2、4.035×104 km2、86.76×104 km2,减少速率分别为-5.641×104 km2/a、-0.813×104 km2/a、 -0.595×104 km2/a。② 20世纪80年代以来,全球增加的耕地主要由草地、林地转化,分别占53.536%、26.148%。新增耕地面积主要分布在非洲南部及中部、澳大利亚东部和北部、南美洲东南部、美国的中部及阿拉斯加、加拿大中部、俄罗斯西部及芬兰北部、蒙古北部等区域。非洲南部的博茨瓦纳为全球耕地增加比例最高区域,增加了80%~90%。③ 20世纪80年代以来,全球耕地换化为其他用地共计1071.946×104 km2,全球减少的耕地主要转化为了草地、林地,分别占比为57.482%、36.000%;全球减少耕地主要分布在非洲中部的苏丹南部、美国中南部、俄罗斯南部及欧洲南部的保加利亚、罗马尼亚、塞尔维亚和匈牙利等国,减少最大的区域为非洲南部,减少了60%。④ 各大洲耕地均表现出向高纬扩张的趋势,全球多数国家表现出新增耕地扩张而原有耕地减少的特点。 相似文献
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Throughout much of the late eighteenth and early nineteenth centuries, the tropics and subtropics were constructed as a relatively homogenous realm. The supposed 'pathological potency' of these regions was assumed to render them particularly hazardous for European constitutions relative to 'temperate' locations. The interior of Africa represented one such apparently pestilential place. This paper examines how the experiences of nineteenth-century missionaries based at various stations in central southern Africa might have been influenced by popular and scientific debates focusing on environment, climate and health in Africa. We also illustrate how their perspectives may have challenged popular homogenized conceptualizations of interior Africa as a uniformly dangerous place for Europeans and helped to identify a spatially varied pathological geography of the region. 相似文献
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运用ArcGIS软件与DPS软件,结合世界银行数据库与《非洲统计年鉴》等,分析21世纪以来非洲跨国移民空间格局及其对FDI影响,结果表明：基于目的地国、原籍国的跨国移民分别集中于北非地区与撒哈拉以南的非洲,其中前者呈现以“摩洛哥-埃及-苏丹”为中心的集聚格局,而后者先以科特迪瓦最为集中,随后逐渐被南非所取代;北非地区FDI分布最为集中且增长稳定,南非、东非、西非和中非四大分区FDI较少且随着时间的推移而日趋平衡;相比基于原籍国的跨国移民,基于目的地国的跨国移民重心与FDI重心重叠性与一致性均较高,即基于目的地国的跨国移民对FDI吸引力更强,这与灰色关联分析法得到的研究结论一致。 相似文献
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Representing environments in flux: case studies from East Africa 总被引：1，自引：0，他引：1
The dominant view in the ecology and anthropology of the 1950s saw populations harmoniously interacting in self-regulating systems; climax forests and stable societies were the ruling hypotheses. Now, however, ecology and social sciences are investigating nature and culture in flux. The flux paradigms of nature and culture describe a human–ecological relationship that is non-equilibrial, historically contingent and constantly negotiated at both material and ideological levels by unequal actors. In this paper, we examine the effect of changing ecological and cultural paradigms on interpretations of environmental change in three areas of East Africa: the North Pare Mountains, Tanzania, the Mkomazi Game Reserve, Tanzania and the Tsavo National Park, Kenya. We explore how discursive and materialist approaches can complement one another, by expanding the domains of ecological inquiry and demanding that analysts cross-check their data for unquestioned assumptions regarding stability, variability and spatial and temporal scales. Rather than testing a ruling hypothesis, we suggest that ecologists and social scientists work with multiple hypotheses, with the aim of understanding the interplay between ecological, environmental and social influences. 相似文献