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publications > fact sheet > FS 2004-3015
U.S. Department of the Interior
Development of a Long-term Sampling Network to Monitor Restoration Success in the Southwest Coastal Everglades: Vegetation, Hydrology, and Sediments
Introduction and History
In October 1992, vegetation monitoring plots were established in heavily damaged areas of mangrove forest on the southwest coast of the Everlgades, along the Lostmans and Broad Rivers (Smith et al., 1994, see Fig. 2). As the permanent plot network was being established, funding was awarded for the South Florida Global Climate Change project (SOFL-GCC). This led to the establishment of a network of hydrological monitoring stations (Anderson and Smith, 2004). Finally, sediment elevation tables (SETs) were installed at many locations. SETs provide the means to measure very small changes (2 mm) in the sediment surface elevation accurately over time (Cahoon et al., 2002). We also set up marker horizons to measure accretion of sediment at each site (Smith and Cahoon, 2003). Sampling sites were located along three transects extending from upstream freshwater wetlands to downstream saltwater wetlands along the Shark, Lostmans and Chatham Rivers in Everglades National Park (Fig. 2).
Our research addresses processes relevant to the following restoration and related questions:
Mortality is occurring at all sites. Sources of tree mortality include continuing demise from damage initially caused by Hurricane Andrew, trees being killed by falling debris, lightning, wind-throw during winter cold fronts, freeze, fire, and several less intense tropical cyclones since Andrew such as Hurricanes Georges, Harvey, Irene, and Mitch. Trees in the smaller-size classes are beginning to perish due to suppression (that is, being overtopped and heavily shaded by larger neighbors, see Fig. 4).
Observed patterns of growth by trees that survived Andrew or that recruited into the plots are hard to explain. Productivity cannot be explained simply by sediment-porewater nutrient concentrations, which are highly variable. Salinity and hydrologic parameters seem most promising to explain patterns of biomass increase following the catastrophic disturbance from Hurricane Andrew.
In addition to influencing mangrove forest structure, the severe disturbance from Hurricane Andrew has affected the stability and elevation of the sediment surface. In the lower Lostmans River, an area highly impacted by the storm, sediment elevation has been decreasing for at least five years (Fig. 5). The forests at the mouth of the Shark River, an area not impacted by Hurricane Andrew, are remaining at constant elevation (Fig. 5). Visual inspection of the data indicates that surface-water dynamics do not seem to be related to sediment-elevation changes.
Sampling of these vegetation plots, hydrology stations, and sediment elevation tables will continue in order to monitor the effect of increasing freshwater inflow that will occur as a major component of the Everglades restoration. We will also use the data currently available to develop performance measures that can be used by CERP.
Anderson, G.H., and Smith, T.J., III, 2004, Data from the mangrove hydrology sampling network for the Lower Shark River, Everglades National Park: Water years 1995 - 2002. U.S. Geological Survey Open-File Report 02-457.
Cahoon, D.R., Lynch, J.C., Hensel, P., Boumans, R., Perez, B.C., Segura, B., and Day, J.W. Jr., 2002, A device for high precision measurement of wetland sediment elevation; I. Recent improvements to the sedimentation-erosion-table. Journal of Sedimentary Research, 72 (5): p. 730-733.
Houston, S.H., and Powell M.D., 2003, Surface wind fields for Florida Bay hurricanes. Journal of Coastal Research, 19: p. 503-513.
Pimm, S., Davis, G., Loope, L., Roman, C., Smith, T.J. III, and Tilmant J., 1994, Hurricane Andrew. BioScience, 44: p. 224-229.
Smith, T.J., III, and Cahoon D.R., 2003, Wetland sediment surface elevation in the Florida Everglades: response to surface water stage variation. Proceedings, 5th International Symposium on Coastal Engineering and Science of Coastal Sediment Processes. East Meets West Productions, Corpus Cristi, TX. CD-ROM.
Smith, T.J., III, Hudson, J.H., Robblee, M.B., Powell, G.V.N., and Isdale, P.J., 1989, Freshwater flow from the Everglades to Florida Bay: A historical reconstruction based on fluorescent banding in the coral Solenastrea bournoni. Bulletin of Marine Science, 44: p. 274-282.
Smith, T.J., III, Robblee, M.B., Wanless, H.R., and Doyle T.W., 1994, Mangroves, hurricanes and lightning strikes. BioScience, 44: p. 256-262.
Funding for this work was provided by the USGS-BRD Global Climate Change Program, the USGS Priority Ecosystems Studies Program, and the Critical Ecosystems Studies Initiative administered by Everglades National Park.
U.S. Department of the Interior, U.S. Geological Survey
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