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Project Summary Sheet

U.S. Geological Survey, Greater Everglades Science Initiative (Place-Based Studies)

Fiscal Year 2003 Project Summary Report

Project Title: Development and Stability of Everglades Tree Islands, Ridge and Slough, and Marl Prairies

Project Start Date: 10/1/00 Project End Date: 9/30/06

Web Sites:

Location (Subregions, Counties, Park or Refuge): Loxahatchee NWR, WCA 2, 3, Everglades Nat'l Park, Big Cypress

Funding Source: USGS Greater Everglades Science Initiative (PBS)

Principal Investigator(s): Debra A. Willard

Project Personnel: C. Bernhardt, M. Corum, C. Holmes, B. Landacre, H. Lerch, M. Marot, W. Orem, T. Sheehan

Supporting Organizations: South Florida Water Management District, Florida Fish & Wildlife Conservation Commission, Loxahatchee NWR, Everglades National Park, Big Cypress National Preserve

Associated / Linked Projects: Interrelation of Everglades Hydrology and Florida Bay Dynamics (Ecology Component), Tides and Inflows in the Mangrove Ecotone (TIME) Model Development, Ecosystem History of the Southwest Coast-Shark River Slough Outflow Area

Overview & Objective(s): Everglades restoration planning requires an understanding the impact of natural and human-induced environmental change on wetland stability. This project initially focused on tree-island development and trends and has expanded into two other systems: the sawgrass ridge and slough system and marl prairies. For each system, restoration targets are being proposed, even though little data exists on their predrainage extent and ecosystem dynamics. Initial goals of the project included: determine geologic and hydrologic controls on tree-island formation, development and sustainability; establish vegetational trends in tree-island development; determine the role of tree islands in the geochemical budget of nutrients; and investigate the use of sediment phosphorus as a tracer of historic bird populations in the Everglades. Investigations of the Ridge and Slough system are directed to: determine the longevity of the features; document changes in spatial extent of sawgrass ridges and sloughs; determine past rates of peat accretion in ridges vs. sloughs; determine whether sawgrass ridges are analogs for sites of tree-island formation; and assess the response of ridges and sloughs to natural and anthropogenic hydrologic changes. Investigations of marl prairies are designed to determine whether the distribution and vegetational composition of marl prairies has changed over the last century.

Status: Cores have been collected on 28 tree islands in Loxahatchee NWR, WCA 2A, 3A, 3B, and Everglades National Park (Shark River Slough and Taylor Slough). Pollen data has been generated for about half of these tree islands. Six transects of cores were collected across "pristine" and altered sawgrass ridges and sloughs sites in WCA 3A. Pollen analysis is complete on surface samples and three transects. In FY03-04, field work includes coring of cypress strands in western WCA 3A and Big Cypress National Preserve and collection of several transects of cores across degraded ridges and slough in WCA 2A. Sediment cores also will be collected in marl prairies in the western Everglades as a pilot study to determine the feasibility of retrospective studies of vegetation in marl-accumulating systems.

Recent & Planned Products:

Willard, D.A., Holmes, C.W., Korvela, M.S., Mason, D., Murray, J.B., Orem, W.H., and Towles, D.T., 2002. Paleoecological insights on fixed tree island development in the Florida Everglades: I. Environmental Controls. In Sklar, F.H., and van der Valk, A. (Eds.), Tree Islands of the Everglades: 117-152.

Orem, W.H., Willard, D.A., Werch, H.E., Bates, A.L., Boylan, A., and Corum, M., 2002. Nutrient geochemistry of sediments from two tree islands in Water Conservation Area 3B, the Everglades, Florida. In Sklar, F.H., and van der Valk, A. (Eds.), Tree Islands of the Everglades: 153-186.

Willard, D.A. and Orem, W.H. 2003. Tree-Islands of the Florida Everglades - A Disappearing Resource. U.S. Geological Survey Open-file Report 03-26: 2 pp.

Bernhardt, C.E., Willard, D.A., and Holmes, C.W., 2003. Development and Stability of the Everglades Ridge and Slough Landscape. U.S. Geological Survey Open-file Report 03-54: 128.

Willard, D.A., Bernhardt, C.E., and Holmes, C.W., in prep. Tree Islands of the Everglades Ridge and Slough Region: Response to Environmental and Climatic Variability. Ecological Monographs (submission in 2003).

Relevance to Greater Everglades Restoration Information Needs: USGS Restoration Goal 1A, 1B (SO1, 2, 3, 5); 2A, B (SG1, 2, 3, 4, 5) and equivalent DOI/CERP Restoration Goals

Key Findings:

  • Tree-island community response to 20th century hydrologic change ranges from nearly total loss of tree species in areas of sustained inundation to expansion of tree islands where water supply decreased due to diversion by canals.
  • Development of mature tree islands took centuries to millennia, depending on location within the Greater Everglades Ecosystem; degradation of tree islands, in comparison, occurred over less than five decades.
  • Sawgrass ridges and sloughs have been distinct features throughout Everglades history; preliminary data indicates changes in spatial extent of ridges, correlated both with climate variability and altered water management practices.

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