一项研究发现，2800年前的一场重大气候变化减少了吹向佛罗里达大沼泽的尘埃，从而改变了该地区的水文、营养供应和植被。佛罗里达大沼泽的典型特征是本就营养贫瘠的湿地在过去的一个世纪里因为人类活动而产生了退化。Paul H. Glaser及其同事注意到了风吹来的尘埃代表了大型泥炭地的一个常常被忽视的营养来源，他们分析了佛罗里达大沼泽国家公园的东北Shark河沼泽的一个沉积物岩心，寻找过去生态系统和大气环流的变化之间的联系。在研究了各种替代指标之后，这组作者发现在大约2800年前，一个湿润的气候时期占据优势，有大量来自撒哈拉的尘埃流入，而沼泽典型的植被占据着佛罗里达大沼泽地区的主要排水出口。然而，从那以后，一个干旱的气候持续存在，风吹来的尘埃急剧减少，支持了锯齿草甸和树岛等赋予了该地区目前外观特征的植被。这组作者提出，这种急剧的气候变化可能是由于一个被称为百慕大高压的天气系统的转变，其转向了东南部，而把向着佛罗里达南部的热带风暴引向了墨西哥湾。（生物谷Bioon.com）
生物谷推荐英文摘要
PNAS doi: 10.1073/pnas.1222239110
Holocene dynamics of the Florida Everglades with respect to climate, dustfall, and tropical storms
Paul H. Glasera,1, Barbara C. S. Hansena, Joe J. Donovanb, Thomas J. Givnishc, Craig A. Strickerd, and John C. Voline
Aeolian dust is rarely considered an important source for nutrients in large peatlands, which generally develop in moist regions far from the major centers of dust production. As a result, past studies assumed that the Everglades provides a classic example of an originally oligotrophic, P-limited wetland that was subsequently degraded by anthropogenic activities. However, a multiproxy sedimentary record indicates that changes in atmospheric circulation patterns produced an abrupt shift in the hydrology and dust deposition in the Everglades over the past 4,600 y. A wet climatic period with high loadings of aeolian dust prevailed before 2800 cal BP (calibrated years before present) when vegetation typical of a deep slough dominated the principal drainage outlet of the Everglades. This dust was apparently transported from distant source areas, such as the Sahara Desert, by tropical storms according to its elemental chemistry and mineralogy. A drier climatic regime with a steep decline in dustfall persisted after 2800 cal BP maintaining sawgrass vegetation at the coring site as tree islands developed nearby (and pine forests covered adjacent uplands). The marked decline in dustfall was related to corresponding declines in sedimentary phosphorus, organic nitrogen, and organic carbon, suggesting that a close relationship existed between dustfall, primary production, and possibly, vegetation patterning before the 20th century. The climatic change after 2800 cal BP was probably produced by a shift in the Bermuda High to the southeast, shunting tropical storms to the south of Florida into the Gulf of Mexico.
