Project Summary Sheet

Project: Vegetation Dynamics in Land-Margin Ecosystems: The Mangroves of South Florida

Web Sites: http://sis2.cr.usgs.gov Science Information System, Project #5001206

Location (Subregions & Counties): Southeast coast, Southwest coast; Miami-Dade, Monroe, Collier

Funding (Source): Critical Ecosystems Studies Initiative (CESI) from Everglades National Park and USGS Place-Based Studies

Principal Investigator(s): Thomas J. Smith III, Tom_J_Smith@usgs.gov; 727-803-8747 x 3130

Project Personnel: Gordon Anderson, Gordon_Anderson@usgs.gov; Kevin Whelan, Kevin_Whelan@usgs.gov; Christa Walker, christa_walker@usgs.gov

Supporting Organizations: NPS, Fish & Wildlife Service, FDEP

Associated / Linked Projects: Understanding and Predicting Global Climate Change Impacts on the Vegetation and Fauna of Mangrove Forested Wetlands in south Florida (Smith / McIvor); Hydrologic Variation and Ecological Processes in the Mangrove Forests of South Florida — Response to Restoration (Saiers/Smith); TIME — Tides and Inflows to the Mangroves of the Everglades (Schaffranek/Jenter). Landscape models for the mangrove forests of the Everglades (Twilley/Doyle).

Overview & Status: Land-margin ecosystems (mangroves, brackish marshes and coastal lakes / back bays) comprise some 40% of Everglades NP. Primary production in these ecosystems fuels the detrital foodweb, which supports sport and commercial fisheries and numerous endangered species (e.g. manatee, wood stork, roseate spoonbill). Freshwater inflow is critical in regulating the salinity and nutrient regimes of these systems and thus their productivity. In August 1992, the land-margin systems of south Florida were severely damaged by Hurricane Andrew. A great potential exists for water management (i.e. regulation of freshwater inflow) to impact the natural recovery processes currently underway.

The research discussed here asks several questions related to how the hydrologic restoration of the Everglades will affect land margin ecosystems, including: 1) How does freshwater inflow regulate primary productivity? 2) How does freshwater inflow interact with other factors (nutrients, soil type) to influence primary productivity? 3) Is there an affect of freshwater inflow on recovery from natural disturbance in these ecosystems? 4) Does freshwater inflow influence below-ground production, peat formation and soil accretion in mangroves? 5) Will the position of the mangrove / marsh ecotone respond to upstream water management? 6) What non-hydrological factors influence the position of the mangrove / marsh ecotone (e.g. soil type and depth, nutrients, fire)?

In addition to providing answers to scientific questions of both basic and applied interest, this project is developing data crucial to the evaluation of hydrological alterations being proposed as part of the "Central & South Florida Project Restudy" and for the development of the Everglades Landscape Model and the Across Trophic Level System Simulation programs. The studies discussed here were initiated under funding from the USGS/BRD South Florida Global Climate Change Program and the Mangrove component of ENP's Hurricane Andrew research program.

This work addresses several of the key gaps in "Performance Measures" for the Restudy (USACOE 1999a, b). At present Performance Measures exist for salinity in Florida Bay and only a single small distributary on the southwest coast (North River). There are NO performance measures for any of the important estuarine biota, plants or animals, on the southwest coast of the restudy area. Potential subjects for performance measures have been identified in the "Conceptual Model" process (USACOE, 1999). Our data will be extremely relevant for defining performance measures to judge response of mangrove vegetation to altered hydrology as proposed in the Restudy.

Needs & Products: This project assists in the maintenance of the Mangrove Hydrology Monitoring Network, a series of 17 stations arrayed along upstream downstream gradients in major rivers on the southwest coast of the Park and in the C-111 basin. The sites are also used for sampling vegetation, and soil elevation changes. The hydrology network provides data on water (ground and surface) stage and conductivity that are used by the TIME and other modeling groups. Water year reports have been prepared and data are available via the TIME website or Everglades NP "Data for Ever" database.

Application to Everglades Restoration: The data generated by this project is being used in models (hydrological and ecological) for gauging restoration success. The data are also being used in the formulation of Performance Measures. For example, data gathered over the past several years from the permanent forest plot network are being used to develop relationships between mangrove growth and survival in relation to salinity — a key variable which will be altered by the addition of freshwater upstream.