zonation). Furthermore, it is important 

 to recognize that the intertidal zone in 

 most parts of Florida changes seasonally 

 (Provost 1974); there is a tendency for 

 sea level to be higher in the fall than in 

 the spring (Figure 2b). As a result the 

 "high marsh" may remain totally dry during 

 the spring and be continually submerged in 

 the autumn. This phenomenon further com- 

 plicates the textbook concept of the in- 

 tertidal, "low marsh" red mangrove and the 

 infrequently flooded, "high marsh" black 

 mangrove. 



Mangrove Acreage in Florida 



Estimates of the total acreage 

 occupied by mangrove communities in 

 Florida vary widely between 430,000 acres 

 and over 500,000 acres (174,000 ha to over 

 202,000 ha). Eric Heald (Tropical 

 Bioindustries, 9869 Fern St., Miami, Fl a.; 

 personal communication 1981) has 

 identified several reasons for the lack of 

 agreement between estimates. These 

 include: (1) inclusion or exclusion in 

 surveys of small bays, ponds and creeks 

 which occur within mangrove forests, (2) 

 incorrect identification of mangrove areas 

 from aerial photography as a result of 

 inadequate "ground-truth" observations, 

 poorly controlled aerial photography, and 

 simple errors of planimetry caused by 

 photography of inadequate scale. 



The two most detailed estimates of 

 area covered by mangroves in Florida are 

 provided by the Coastal Coordinating Coun- 

 cil, State of Florida (1974) and Birnhak 

 and Crowder (1974). Considerable dif- 

 ferences exist between the two estimates. 

 The estimate of Birnhak and Crowder 

 (1974), which is limited to certain areas 

 of south Florida, appears to be unreal is- 

 tically high, particularly for Monroe 

 County (Eric Heald, personal communication 

 1981). Coastal Coordinating Council 

 (1974) estimates a total of 469,000 acres 

 (190,000 ha) within the State and suggests 

 an expected margin of error of 15% (i.e. 

 their estimate lies between 400,000 and 

 540,000 acres or 162,000 and 219,000 ha). 



According to this survey, ninety percent 

 of Florida's mangroves are located in the 

 four southern counties of Lee (35,000 

 acres or 14,000 ha), Collier (72,000 acres 

 or 29,000 ha), Monroe (234,000 acres or 

 95,000 ha), and Dade (81,000 acres or 

 33,000 ha). 



Much of the area covered by mangroves 

 in Florida is presently owned by Federal, 

 State or County governments, or by non- 

 profit organizations such as the National 

 Audubon Society. Approximately 280,000 

 acres (113,000 ha) fall into this category 

 (Eric Heald, personal communication 1981). 

 Most of this acreage is held by the 

 Federal Government as a result of the land 

 being including within the Everglades 

 National Park. 



1.4 MANGROVE SPECIES DESCRIPTIONS 



The following descriptions come 

 largely from Carlton (1975) and Savage 

 (1972); see these publications for further 

 comments and photographs. For more 

 detailed descriptions of germinating seeds 

 (propagules) see section 2.3. The three 

 species are shown in Figure 3. 



The Black Mangrove (Avicennia germinans ) 



Avicennia germinans is synonymous 

 with A. nitida and is a member of the 

 family Avicenniaceae (formerly classed 

 under Verbenaceae). The tree may reach a 

 height of 20 m (64 ft) and has dark, scaly 

 bark. Leaves are 5 to 10 cm (2 to 4 

 inches) in length, narrowly elliptic or 

 oblong, shiny green above and covered with 

 short, dense hairs below. The leaves are 

 frequently encrusted with salt. This tree 

 is characterized by long horizontal or 

 "cable" roots with short vertical aerating 

 branches (pneumatophores) that profusely 

 penetrate the substrate below the tree. 

 Propagules are lima-bean shaped, dark 

 green while on the tree, and several 

 centimeters (1 inch) long. The tree 

 flowers in spring and early summer. 



