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复活节岛位于东南太平洋上,面积约117平方公里,现属智利共和国的瓦尔帕莱索地区,离南美大陆智利约3000公里,离太平洋上其他岛屿距离也很远。所以它是东南太平洋上一个孤零零的小岛。复活节岛是世界上与世隔绝的岛屿之一,离其最近有人定居的皮特开恩群岛也有2,075公里距离。该岛呈三角形,由三座火山组成。岛上因有巨石雕像而闻名于世。为什么在这个小岛上会有如此多的石像,巨石人像是谁雕刻的,寓意何在,一直是千古之谜。 相似文献
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In the last decade, there has been increasing interest in climate change, pasture degradation and its driving forces, and innovations in nomadic pastoralism on the Tibetan Plateau. However, little is known of indigenous strategies of adaptation to pasture degradation, which limits the effectiveness of adaptation strategies planned by local government. This paper analyzes nomads’ strategies of adaptation to pasture degradation on the basis of a field survey of three townships of Dalag County in the source regions of the Yangtze and Yellow rivers. Pastures there have evidently degraded, with pastures in Wasai mainly in a state of slight or medium degradation and those in Manzhang and Jianshe in a state of medium or severe degradation. With the degradation of pasture, the grazing time is reduced, which affects the livelihoods of nomads. Although the Four-Package Project has commenced in this region, there is still severe fodder shortage in winter and spring. The traditional hay storage strategy does not work because of pasture degradation, and few nomads establish fenced and artificial pastures. Therefore, nomads have employed other strategies, such as renting pasture, providing supplementary feed, and diversifying their livelihoods. Local strategies taken by nomads can provide valuable insights into ecological restoration and livelihood improvement in the region and suggest changes to means promoted by local government. It is necessary to seek new means that combine the best aspects of nomadic pastoralism with modern stockbreeding technologies to help nomads adapt to pasture degeneration and improve their livelihoods. 相似文献
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海岸线的长度依赖于测量尺度,因此没有确定的测量结果:尺度越小,测量的长度值越大。国境线的测量也具有类似的尺度依赖性。这种性质与分形性质有关。分形的本质是标度对称性,而对称性意味着某种不可观测量。由于标度对称性的存在,一些地理现象的基本测度(如长度、面积)无法准确计算。中国、美国等国家的国土面积大小都没有确切的数据:在版图没有任何变动的情况下,不同时期、不同机构的测量结果不一致,有时甚至大相径庭。本文借助分形模型和标度对称思想探讨这一问题。假定一个国家包括漫长的海岸线,则其国土可以分解两部分:主体部分可以用Koch岛模型刻画,岛屿部分则可以用Pareto分布描述。这两部分叠加的结果是,国土总面积随着测量尺度的减少而逐步增加。因此,中国政府可以正式公布国土面积的最新测量数据,而不必继续担心由此引发的国际政治争端。 相似文献
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喀喇昆仑山乔戈里峰,海拔8611米,系世界第二高峰。这里现代冰川的发育规模,远远超过海拔8848米的世界第一高峰所在的珠穆朗玛峰区。乔戈里峰南侧降水丰富,巴尔托落冰川长达66公里,而珠穆朗玛峰区最大冰川——绒布冰川只有22公里。乔戈里峰北坡比较干燥,但乔戈里冰川,仍长达22.5公里,也超过绒布冰川。乔戈里峰西北更有长42公里,面积 相似文献