Climate-driven ecosystem succession in the Sahara:: The past 6000 years
Climate-driven ecosystem succession in the Sahara:: The past 6000 years
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DOI：
10.1126/science.1154913
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发表时间：
2008-05-09
期刊：
影响因子：
56.9
通讯作者：
Engstrom, D. R.
中科院分区：
文献类型：
--
作者：
Kroepelin, S.;Verschuren, D.;Engstrom, D. R.
自全新世中期以来，撒哈拉沙漠的干燥化已经消除了所有的自然档案，只有少数记录了它从“绿色撒哈拉”到现在的极端干旱沙漠的转变。我们从乍得北方连续6000年的古环境重建表明，区域陆地生态系统的逐步干燥，以响应非洲季风和当地水生生态系统的水文突变控制的特定地点的阈值减弱的日照强迫。热带树木和萨赫勒草原覆盖的强烈减少使得从4300日历年到现在（cal yr B）的大规模粉尘动员成为可能。P.）。今天的沙漠生态系统和区域风况是在B约2700卡/年建立的。这种非洲湿润期在撒哈拉东部逐渐而不是突然终止的现象表明，地球物理学对气候的反馈相对较弱。
Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a "green Sahara" to the present hyperarid desert. Our continuous 6000- year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site- specific thresholds. Strong reductions in tropical trees and then Sahelian grassland cover allowed large- scale dust mobilization from 4300 calendar years before the present ( cal yr B. P.). Today's desert ecosystem and regional wind regime were established around 2700 cal yr B. P. This gradual rather than abrupt termination of the African Humid Period in the eastern Sahara suggests a relatively weak biogeophysical feedback on climate.