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Wetlands & ecological models

Conceptual model: South Florida

Generic modeling framework

South Florida Landscape Conceptual Model

Soils (and sediments) are in a long term, ca. decadal, balance between processes of accumulation and oxidation (and erosion), and are closely integrated with the development of different habitats.

In regions of long hydroperiods where water ponds for much of the year, peat soils tend to accrete organic material that come from plant mortality and litterfall. Under shorter hydroperiods when those soils are exposed more frequently to the air (and thus more aerobic conditions), oxidation of the organic matter tends to reduce the depth of peat. This process is governed by microbial dynamics, and can be accelerated with higher nutrient availability.

The oxidation of soil releases nutrients from tightly bound organic forms into inorganic chemical forms that are more readily available to plants and microbes. Disturbances such as droughts and "muck" fires can have significant impacts on peat soils, rapidly oxidizing the organic carbon, but leaving behind much of the nutrients to which the ecosystem may respond.

Throughout much of the Everglades is a upper-soil layer of flocculent (fluffy) organic material that is partly live periphyton, but is principally the organic material from dead periphyton and macrophytes. This "floc" appears to play a critical role in nutrient cycling and water-borne transport of organic material among habitats - and potentially forms part of a detrital food web for animals. Thus, soils are closely integrated with water quality and plant or periphyton growth, and respond strongly to changes in hydrology. Inorganic constituents of soils vary in importance through the Everglades system, with calcitic periphyton sequestering calcium and phosphorus into an inorganic component that forms marl soils.

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