Home Preface Synopsis History of the Study Regional System - Early Ecosystem > Changing System - Ecosystem Models Ecosystems Hydrologic Systems Final Word References Appendices PDF version

After 1900 men came in increasing numbers to south Florida and began to modify the ecosystem. Areas were drained for farming; bay-front areas were filled; and trees were removed. All this activity required additional sources of energy and material other than those available locally, so machinery, money, and fuel were brought into south Florida. The south Florida ecosystem that had developed over thousands of years gave way to a new three-part ecosystem which incorporated an agricultural component, an urban component, and a component derived from the natural ecosystem. These Components are interrelated through the flow of energy and resources. The agricultural and urban systems rely on the remaining natural systems to provide for the commodities and free services of land, water, and oxygen production. These are needed for recycling nutrients, dispersing and detoxifying pollutants, retaining biological diversity, and producing fish and wildlife. If the natural systems are reduced, the services they once provided free must be provided by an energy subsidy, which is often costly. (A further discussion of systems ecology and ecological modeling is given in Appendix I.)

Outdoor recreation, which is largely dependent on the remaining natural systems and their services, is an important component of the south Florida economy and lifestyle. The subtropical coastal environment is conducive to year-round tourism and outdoor recreation such as swimming, fishing, boating, and surfing, which contribute substantially to the economy of the region (U.S. Bur. Outdoor Recreation, 1973).

Much of the land suitable to meet the growing population pressures has already been developed. Lands remaining often require dredge and fill, additional drainage, or other types of land preparation to make them habitable. Such activities are usually destructive to natural systems (Birnhak and Crowder, 1974).

The temporal and spatial distribution of water may be considered the primary ecological factor in the south Florida regional ecosystem, particularly as it relates to man and his role in the system. The source of freshwater is rainfall that is temporarily stored in Lake Okeechobee, the Big Cypress Swamp, the conservation areas, Everglades National Park, and the shallow aquifers. Each of the storages is directly or indirectly connected to the sea, which can be considered the sink of the freshwater system. Water is transported throughout the hydrological system by canals, rivers, creeks, sloughs, sheet flow, and underground flow and through the air as water vapor. Recent dry-season water deficiencies are linked to an expanding population, which requires diversions of water from the natural and agricultural systems. The agricultural systems also depend on an adequate water supply, without which lower productivity results.

Agricultural and urban systems require an input of energy beyond that supplied naturally. Most of this energy is imported as fossil fuel or as a fossil-fuel product. For example, farmers not only use energy (fuel) directly for tractors but also indirectly in farm machinery, pesticides, and fertilizers that require energy for their production. modern urban societies, in particular, require large inputs of outside energy to build and maintain their complicated structures of transportation, schools, laws, communication networks, buildings, and public services. As cities grow, so do energy requirements; it these are not met, stress occurs and the quality of life deteriorates.

In recent years urban growth in south Florida has been rapid. Population increase from slightly less than 0.5 million in 1940 to 1.5 million in 1970. If present trends continue, by 2000 south Florida would have more than 4.4 million residents, or about an 80-percent increase from 1970. As the permanent and visiting population increases, more services such as parks, schools, utilities, and transportation are needed. As a result, the cost per capita to supply basic needs often increases, and it becomes increasingly difficult and expensive to furnish these services without disruptive effects.

Because of generally unplanned growth, south Florida has an increasing number of socioeconomic environmental problems. Land zoning has been relatively ineffective in regulating growth patterns because it has been based on political, rather ecological, boundaries and on short-term economic benefits. The problems related to growth can be expected to increase and intensify unless growth patterns change and long-range land-use planning is implemented.

A regional land-use plan with enforcement provisions is one way to regulate growth and development. Such a plan requires analysis of complex social, economic, and environmental factors. Systems analysis provides a method for generating a plan of this type. In south Florida the foundation has been laid for such an analysis using ecosystem models that simulate the energy sources, storages, and flows in the region.