CHAPTER 7 

 ESTUARINE AND SALTWATER WETLANDS 



7.1 PREVIOUS LITERATURE 

 REVIEWS AND SUMMARIES 



Recently Odum et al. (1982) 

 summarized the existing literature 

 on a major component of the south- 

 western Florida coast in a document 

 entitled: The Florida Mangrove 



Zone: A Community Profile . Since 

 this document draws from the same 

 sources of information as the pre- 

 sent report, it is considered redun- 

 dant to attempt to summarize the 

 same literature. Consequently, the 

 following discussion deals only with 

 those ecological factors that are 

 specific to the watershed and estu- 

 aries of the study area. It is 

 strongly suggested that the reader 

 consult the above document for a 

 more complete review of the auteco- 

 logy and synecology of the Florida 

 mangrove zone. 



7.2 HABITAT ZONATION 



Figure 48 (from Browder et al. 

 1973) identifies the general habi- 

 tat zonations of the estuarine 

 and saltwater wetland ecosystem. 

 In areal coverage, mangrove forest 

 is by far the predominant habitat. 

 Salt marsh and open water estu- 

 arine habitats are next in terms 

 of decreasing relative abundance. 

 Beach and dune vegetation is limit- 

 ed to the elevated sand ridges 

 behind the three capes of Cape 

 Sable and a narrow beach at High- 

 land point between Lostman's and 

 Broad Rivers (Craighead 1971). 

 Salt flats (or prairies) which 

 do not show up on the map at 

 this scale are interspersed within 

 the mangroves along the northern 

 fringe of Florida Bay and the gulf 

 coast. 



7.21 MANGROVE FORESTS 



Distributions of vegetation 

 within the mangrove zone follow two 

 complimentary trains of thought. 

 One is strictly phytosociological, 

 based on the theory of successional 

 relationships between species asso- 

 ciations (Davis 1940); the other is 

 based on consideration of the envi- 

 ronmental factors favoring species 

 dominance and physiognomy of forest 

 growth (Lugo and Snedaker 1974) . As 

 the latter authors point out, these 

 two approaches are complimentary 

 rather than mutually exclusive. 



Figure 49 presents a comparison 

 of these two schemes. The Davis 

 approach (Figure 49a) presents an 

 empirical summary of the major habi- 

 tats of the study area with emphasis 

 on the mangrove zonation relative to 

 tide levels. With the exception of 

 Davis' interpretation that mangroves 

 actively build land and that succes- 

 sional processes per se are involved 

 in the empirical trends of Figure 

 49a, the diagram is a fair represen- 

 tation of vegetation associations in 

 the mangrove zone. Presently the 

 general consensus of opinion is that 

 mangroves, through their ability to 

 trap sediments, act as land stabili- 

 zers rather than land builders (Odum 

 et al. 1982). Other physical forces 

 such as sea level fluctuation, long 

 term drainge patterns, and hurri- 

 canes exert the primary controlling 

 influence on exactly where the land 

 ends and the ocean begins. 



If one were to incorporate 

 environmental factors into Davis' 

 Figure 49a, such as topography and 

 hydrology, the mangrove forest types 

 of Figure 49b (Lugo and Snedaker, 



145 



