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Open-File Report 2006-1355

Marl Prairie Vegetation Response to 20th Century Hydrologic Change

By Christopher E. Bernhardt and Debra A. Willard

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We conducted geochronologic and pollen analyses from sediment cores collected in solution holes within marl prairies of Big Cypress National Preserve to reconstruct vegetation patterns of the last few centuries and evaluate the stability and longevity of marl prairies within the greater Everglades ecosystem. Based on radiocarbon dating and pollen biostratigraphy, these cores contain sediments deposited during the last ~300 years and provide evidence for plant community composition before and after 20th century water management practices altered flow patterns throughout the Everglades. Pollen evidence indicates that pre-20th century vegetation at the sites consisted of sawgrass marshes in a peat-accumulating environment; these assemblages indicate moderate hydroperiods and water depths, comparable to those in modern sawgrass marshes of Everglades National Park. During the 20th century, vegetation changed to grass-dominated marl prairies, and calcitic sediments were deposited, indicating shortening of hydroperiods and occurrence of extended dry periods at the site. These data suggest that the presence of marl prairies at these sites is a 20th century phenomenon, resulting from hydrologic changes associated with water management practices.

First posted May 14, 2010

For additional information contact:

USGS Geology and Environmental Change Science Center
Box 25046, Mail Stop 980
Denver, CO 80225

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Suggested citation:

Bernhardt, C.E., Willard, D.A., 2006, Marl prarie vegetation response to 20th century hydrologic change: U.S. Geological Survey Open-File Report 2006-1355, 14 p.

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