一項研究發(fā)現(xiàn),，2800年前的一場重大氣候變化減少了吹向佛羅里達大沼澤的塵埃,，從而改變了該地區(qū)的水文、營養(yǎng)供應和植被,。佛羅里達大沼澤的典型特征是本就營養(yǎng)貧瘠的濕地在過去的一個世紀里因為人類活動而產生了退化,。Paul H. Glaser及其同事注意到了風吹來的塵埃代表了大型泥炭地的一個常常被忽視的營養(yǎng)來源，他們分析了佛羅里達大沼澤國家公園的東北Shark河沼澤的一個沉積物巖心,，尋找過去生態(tài)系統(tǒng)和大氣環(huán)流的變化之間的聯(lián)系,。在研究了各種替代指標之后，這組作者發(fā)現(xiàn)在大約2800年前，一個濕潤的氣候時期占據優(yōu)勢,，有大量來自撒哈拉的塵埃流入,，而沼澤典型的植被占據著佛羅里達大沼澤地區(qū)的主要排水出口。然而,，從那以后,，一個干旱的氣候持續(xù)存在，風吹來的塵埃急劇減少,，支持了鋸齒草甸和樹島等賦予了該地區(qū)目前外觀特征的植被,。這組作者提出，這種急劇的氣候變化可能是由于一個被稱為百慕大高壓的天氣系統(tǒng)的轉變,，其轉向了東南部,，而把向著佛羅里達南部的熱帶風暴引向了墨西哥灣。（生物谷Bioon.com）
生物谷推薦英文摘要
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.
