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首页> 外文期刊>Bothalia: African Biodiversity & Conservation >Histoire de la végétation et du climat de l'Afrique nord-tropicale au Quaternaire recent*
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Histoire de la végétation et du climat de l'Afrique nord-tropicale au Quaternaire recent*

机译：新近第四纪北非热带植被和气候的历史*

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LATE QUATERNARY HISTORY OF VEGETATION AND CLIMATE OF TROPICAL NORTH AFRICAThe critical examination o f available pollen data from the vegetation of the Sahara allows one to conclude that this vegetation has gone through but few qualitative changes during the last twenty thousand years. In particular, one notices an extension in the Sahara of tropical Sahel taxa about the middle of Holocene. Quantitatively, some pollen and geological data converge to Show that the Saharian plains were extremely arid between about 20 000 and 15 000 years BP and that on the mountains the vegetation became very sparse. A new colonization began on the mountains about 15 000 years ago.The pollen study of Holocene sediments from the central part o f the Chad basin was done in the Tjéri station. The results of this study exhibit a major change near 7 000 years BP, characterized in the Sahel zone by a dramatic extension o f arboreal taxa until about 5 000 years BP, probably corresponding to northward extension of the sahel savanna. One important change took place also at the same time in the wet north tropical zone where, between about 7 000 and 4 000 years BP, there occurred an extension of taxa growing presently on the well-leached soils of interfluves.Such a change near 7 000 years BP also appears in the available stratigraphical, sedimentological and pedological data from tropical north Africa. One observes particularly that, between 15 000 and 7 000 years BP, the
机译：热带北非植被和气候的第四纪晚期对撒哈拉沙漠植被的现有花粉数据进行的严格检查可以使人们得出这样的结论：该植被在过去两万年中经历了很少的质变。特别是，人们注意到撒哈拉沙漠中的全新世中部扩展了热带萨赫勒分类群。从数量上讲，一些花粉和地质数据的融合表明，撒哈拉平原在BP约2万至1.5万年之间极为干旱，而山区植被却十分稀疏。大约1万5千年前，山区开始了新的殖民化。乍得盆地中部全新世沉积物的花粉研究在Tjéri站进行。这项研究的结果显示，在7,000年BP附近发生了重大变化，其特征是在萨赫勒地区的乔木类群急剧扩展到大约5,000年BP，这可能与萨赫勒热带稀树草原向北扩展有关。一个重要的变化也同时发生在潮湿的北热带地区，在大约7,000年至4,000年BP之间，目前在互溶性良好的淋溶土壤上生长的类群扩展，这种变化接近7在北非热带地区可用的地层，沉积学和土壤学数据中也出现了000年BP。有人特别指出，在BP的15000至7000年之间，

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