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Climate-vegetation dynamics in western tropical Africa: 150,000 years of past environmental change from Lake Bosumtwi (Ghana)

热带非洲西部的气候植被动态：博苏姆特维湖（加纳）过去 15 万年的环境变化

基本信息

批准号：
NE/G000824/1
负责人：
William Gosling
金额：
$ 15.51万
依托单位：
The Open University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG000824%2F1
关键词：
Climate vegetation dynamics western tropical

项目摘要

Observations indicate that the extent of the tropical climate zone is more sensitive to global climate change than model predictions suggest and ecological investigations are finding variation within both forest and savannah biomes to be extremely sensitive to climate change. However, the dynamics of how tropical vegetation responds to climate change remains controversial. To explore the relationship between the global climate system and tropical vegetation it is necessary to examine past records of vegetation change through periods of known global climate change, e.g. through glacial-interglacial cycles. The most effective way of examining terrestrial vegetation change is through fossil pollen records from continuous, and chronologically well constrained, lake sediments. However, few fossil pollen lake records exist from the tropics which cover one, or more, complete glacial-interglacial cycle. Pollen records documenting past vegetation change in the lowland tropics of Africa are particularly scarce with only three records from terrestrial lakes which extend beyond the current interglacial published. These are: 1) Bosumtwi (Ghana) which extends back c. 28 thousand calendar years Before Present (kyr BP), 2) Barombi Mbo (Cameroon) covering c. 28 kyr BP, and 3) Ngamakala (Congo) c. 24 kyr BP. Terrestrial vegetation change in tropical Africa has been inferred through glacial-interglacial cycles from pollen analysis on marine cores in the Gulf of Guinea (c. 150 kyr BP) and off the cost of north west Africa (>500 kyr BP; ODP 658). However, interpretation of these data is complicated by the need to understand changes in ocean currents, wind fields and depositional patterns. This paucity of data means that the likely nature of vegetation response to predicted future changes in tropical climate remains essentially unexplored. To shed light on the likely response of tropical vegetation to global climate change and to provide the first data from a terrestrial record in tropical Africa older than 30 kyr I propose to examine fossil pollen from lake sediments raised from Lake Bosumtwi (Ghana) in 2004 at two key time scales and resolutions: 1) to examine vegetation response to major, astronomically forced, global climate change events through the last glacial-interglacial cycle (c. 150 kyr BP) at sub-millennial resolution, and 2) to explore vegetative response to rapid global climate change, e.g. Heinrich events, during the period 30-10 kyr BP at centennial resolution.

观测结果表明，热带气候区的范围对全球气候变化的影响比模型预测的更为敏感，生态调查发现森林和草原生物群落内的变化对气候变化极为敏感。然而，热带植被如何响应气候变化的动态仍然存在争议。为了探索全球气候系统和热带植被之间的关系，有必要检查已知全球气候变化时期的植被变化的过去记录，例如通过冰期-间冰期循环。检查陆地植被变化的最有效方法是通过连续且按时间顺序严格限制的湖泊沉积物中的化石花粉记录。然而，热带地区很少有化石花粉湖记录涵盖一个或多个完整的冰期-间冰期循环。记录非洲低地热带地区过去植被变化的花粉记录尤其稀少，仅发布了三份来自超出当前间冰期的陆地湖泊的记录。它们是： 1) Bosumtwi（加纳），向后延伸c。现在之前的 28000 日历年（kyr BP），2）Barombi Mbo（喀麦隆）覆盖 c。 28 kyr BP，和3）Ngamakala（刚果）c。 24 吉尔BP。热带非洲的陆地植被变化是通过对几内亚湾（约 150 kyr BP）和西北非洲（> 500 kyr BP；ODP 658）海洋核心花粉分析的冰期-间冰期循环推断出来的。然而，由于需要了解洋流、风场和沉积模式的变化，对这些数据的解释变得复杂。数据的缺乏意味着植被对预测的热带气候未来变化的可能反应本质上仍未被探索。为了阐明热带植被对全球气候变化的可能反应，并提供来自热带非洲超过 30 kyr 的陆地记录的第一批数据，我建议以两个关键的时间尺度和分辨率检查 2004 年从博苏姆特维湖（加纳）产生的湖泊沉积物中的花粉化石：1）检查植被对上一个冰期-间冰期期间主要的、天文强迫的全球气候变化事件的反应周期（约150 kyr BP）以亚千禧年分辨率，2）探索植物对快速全球气候变化的反应，例如海因里希事件，在 30-10 kyr BP 期间以百年纪念决议。