Big Cypress regional ecosystem conceptual ecological model

Abstract

The Big Cypress region of southwest Florida is a diverse mosaic of upland pine flatwoods and hardwood hammocks, herbaceous wet prairies and marshes, and forested wetlands. Besides large natural landscapes, it includes extensive areas of residential and agricultural development. Dominant natural controlling factors are hydrology on the low relief land surface and fire in a subtropical environment with a strong wet-dry seasonal cycle of rainfall. Human influences on the Big Cypress ecosystem are all associated with extensive residential and agricultural development. Lowered water levels and shortened hydroperiods cause shifts to drier communities, which leads to habitat loss and more intense fires. Higher nutrient concentrations associated with agriculture and more mineralized ground-water inputs from a variety of sources favor nuisance and exotic plant species. Fragmentation of the plant community mosaic interferes with seasonal expansion and contraction of wetland water bodies and associated seasonal movements of animal populations. Fragmentation also interferes with wildlife movements and the natural spread of fire across the landscape. Disturbed environments along edges created by fragmentation facilitate invasion of natural plant and animal communities by exotic species. Efforts to eradicate fire have eliminated large areas of early successional communities, while creating high fuel loads that ultimately result in very destructive fires. The spread of exotic plants is resulting in the replacement of large areas of native plant communities, but the effects of exotic animal invasions on native animal populations are poorly known. The objective of this paper is to present a conceptual model of the major human influences on the Big Cypress region, and how they affect natural processes and selected components of the ecosystem.