The natural area of the Everglades is faced with the problem of an altered landscape due to large-scale water management (canals and levees) that has redirected water that historically flowed throughthe Everglades. These canals and levees impound and redirect water, resulting in a mosaic of natural wetlands, urban and agricultural land use. The object of the ELM project is to develop a simulation modeling tool for evaluation of scenarios of water management. This model is envisaged as having the following properties:
The Everglades of Florida, USA, is a mosaic of urban, agricultural, marsh and forest habitats in a vast neotropical wetland, with a pattern that has been altered by water management via canals, levees, and water control structures. We developed a spatially explicit model of ecosystem processes and landscape succession to evaluate landscape response to different water quantity/quality management scenarios. A GIS partitions the model area into ~10,000 1 km2 grid cells, storing data such as initial habitat types, elevation, and water levels. An ecosystem unit model is replicated in each homogeneous cell and parameterized according to the habitat type. The unit model simulates hydrology, soil & water nutrients, periphyton biomass & community type, and vegetation biomass & community type, with numerous feedbacks among these components. Water and nutrients flux among the model's raster grid cells and canal vectors, with controls at management structures that alter water delivery in the system using output data from the South Florida Water Management Model. Unit model dynamics respond to the varying water quantity and quality in the landscape mosaic, while the pattern of vegetation (habitat) type may change in response to changing hydrology and nutrient availability.
Most components of the Everglades Landscape Model have been calibrated with available data, and we are evaluating different algorithms and hypotheses concerning habitat transitions. The model is now one of the tools in a research and management program at the South Florida Water Management District (SFWMD) to aid in focusing research and evaluating changes in water management in the south Florida region.
Spatial Model Hierarchy
The Everglades Landscape Model employs the Spatial Modeling Environment, SME version 1 to develop a spatially explicit, dynamic simulation model of the ecosystems within a particular landscape. The SME executes the unit General Ecosystem Model (for the vertical solutions) within each cell across the model landscape. The landscape is comprised of different habitats distributed across the model cells, with canal vectors superimposed across this raster grid. Only the model parameters vary with habitats, with the model structure being fixed for all habitat types. Mass of water and nutrients are transported among neighboring cells, while canal vectors flux water and nutrients rapidly across the system, exchanging mass with adjacent cells. The pattern of the landscape may affect horizontal fluxes and within-cell ecosystem processes, while the long-term cell dynamics can alter the pattern of the raster landscape. The habitat-type designation may change during the course of a simulation in response to changing ecological attributes of the grid cells.
(see the schematic diagram).
The pattern of the landscape may affect horizontal fluxes and cell ecosystem processes, while the long-term cell dynamics can alter the pattern of the raster landscape. Canal/levee vector fluxes are an important component of the hydrology/ecology of the ELM.
ELM homepage: http://www.sfwmd.gov/org/erd/esr/ELM.html
South Florida Water Management District (SFWMD)
ELM is contructed in a hierarchy using the ecological models, The General Ecosystem Model (GEM)and The Conservation Area Landscape Model (CALM).
Maryland International Institute for Ecological Economics