A Total System Conceptual Ecological Model for South Florida
John C. Ogden
South Florida Water Management District, West Palm Beach, FL, USA
Tomma Barnes
South Florida Water Management District, Fort Myers, FL, USA
Steve M. Davis
South Florida Water Management District, West Palm Beach, FL, USA
The Central and Southern Florida Project Comprehensive Review Study included
an Applied Science Strategy that has been adopted as a process for effectively
linking science and management during all phases of the Comprehensive
Everglades Restoration Plan (CERP). The Applied Science Strategy is a total
systems and multi-disciplinary process that can be used as a planning tool for
designing the restoration plan and for determining the most appropriate
restoration targets, and the best measures for each of these targets, during and
following the implementation of the restoration programs. An essential step in
the Applies Science Strategy is the creation of a set of conceptual ecological
models of the major physiographic regions in south Florida that will be directly
affected by the Comprehensive Everglades Restoration Plan. The purpose of
these models is to show how ecosystems are stressed, to identify the sources of
this stress, and to be used as a guideline for establishing performance measures
for stressors and attributes identified in the process.
These simple, non-quantitative models are an effective planning tool for
developing a consensus regarding a set of causal hypotheses, which explain the
affects that the major anthropogenic stressors have on the ecosystem. Each model
identifies the attributes in the natural systems that are the best indicators of the
changes that have occurred as a result of the stressors. Each model also delineates
the ecological linkages between the stressors and the attributes and the most
appropriate measure for each of the attributes.
Originally, nine conceptual models were developed for physiographic regions in
south Florida. These include Florida Bay, Biscayne Bay, St. Lucie/Indian River
Lagoon, Caloosahatchee Estuary, Big Cypress Basin, Lake Okeechobee,
Everglades Ridge and Slough, Everglades Marl Prairie, and Everglades Mangrove
Transition Zone. More recently, a conceptual model for the Total Greater
Everglades System was developed.
The Total System Conceptual Model is designed to show the ecological linkages
among the major working hypotheses and cause and effect relationships that
explain the important effects of system-wide stressors on the South Florida
Ecosystem. These stressors, which include sea level rise, water management
practices, and changes in land use patterns, certainly echo those seen in the set of
regional conceptual models that were previously developed. Our purpose in
creating the Total System Model was to identify the working hypotheses that
explain the major ecological changes that have occurred at the larger scale of the
South Florida Ecosystem. The Total System Model integrates these major,
system-wide working hypotheses that are common to several or all of the regional
conceptual models, along with ecological linkages that are working across multilandscape boundaries and therefore are not adequately addressed with a regional
model. One additional question addressed by the Total System Model is whether
there are major stressors and ecological effects that, because they are operating at
such a large scale, have not been adequately characterized by the regional models.
Some important stressors have been omitted from the Total System Model. This
may be because the effects of the stressor on a region's internal ecology have
specific, regional effects and are better characterized in the appropriate regional
model.. Six stressors, altered hydrology, exotics and invasives, excess nutrients,
mercury contamination, compartmentalization, and loss of spatial extent, have
been identified for the Greater Everglades Ecosystem.
Therefore, the Total System Model looks at the bigger picture, to pick up where
regional models leave off, to look at the interactions among regional models,
including the upstream and downstream effects of what happens across
boundaries. Many of the attributes chosen as indicators of these system-wide
events are similar to those seen in other models. Here, however, they indicate
more broad scale effects. Five ecological attributes identified in the Total System
Model include wading birds; endangered and keystone species; fish and
invertebrate communities; upland and wetland vegetation; and aquatic vegetation.
In CERP, the Total System Model will be used to create a new set of total system
performance measures and to add a total system component to the Monitoring and
Assessment Plan. In addition, it will provide the opportunity to simplify regional
models by shifting certain system-wide issues to the Total System Model.
Tomma Barnes SFWMD
2301 McGregor Blvd
Fort Myers, FL 33901
239-338-2929 x7771
tbarnes@sfwmd.gov