The White Mangrove (Laguncularia racemosa ) 



The white mangrove is one of 450 

 species of plants in 18 genera of the 

 family Combretaceae (synonymous with 

 Terminal iaceae). It is a tree or shrub 

 reaching 15 m (49 ft) or more in height 

 with broad, flattened oval leaves up to 7 

 cm (3 inches) long and rounded at both 

 ends. There are two salt glands at the 

 apex of the petiole. The propagule is 

 very small (1.0 to 1.5 cm or 0.4 to 0.6 

 inches long) and broadest at its apex. 

 Flowering occurs in spring and early 

 summer. 



The Red Mangrove (Rhizophora mangle ) 



The red mangrove is one of more than 

 70 species in 17 genera in the family 

 Rhizophoraceae. This tree may reach 25 m 

 (80 ft) in height, has thin grey bark and 

 dark red wood. Leaves may be 2 to 12 cm 

 (1 to 5 inches) long, broad and blunt- 

 pointed at the apex. The leaves are 

 shiny, deep green above and paler below. 

 It is easily identified by its charac- 

 teristic "prop roots" arising from the 

 trunk and branches. The penci 1 -shaped 

 propagules are as much as 25 to 30 cm (10 

 to 12 inches) long after germination. It 

 may flower throughout the year, but in 

 Florida flowering occurs predominately in 

 the spring and early summer. 



1.5 MANGROVE COMMUNITY TYPES 



Mangrove forest communities exhibit 

 tremendous variation in form. For 

 example, a mixed scrub forest of black and 

 red mangroves at Turkey Point on Biscayne 

 Bay bears little resemblance to the 

 luxuriant forests, dominated by the same 

 two species, along the lower Shark River. 



Lugo and Snedaker (1974) provided a 

 convenient classification system based on 

 mangrove forest physiogomy. They identi- 

 fied six major community types resulting 

 from different geological and hydrological 

 processes. Each type has its own charac- 

 teristic set of environmental variables 

 such as soil type and depth, soil salinity 



range, and flushing rates. Each community 

 type has characteristic ranges of primary 

 production, litter decomposition and car- 

 bon export along with differences in 

 nutrient recycling rates, and community 

 components. The community types as shown 

 in Figure 4 are as follows: 



(1) Overwash mangrove forests - 

 these islands are frequently overwashed by 

 tides and thus have high rates of organic 

 export. All species of mangroves may be 

 present, but red mangroves usually domi- 

 nate. Maximum height of the mangroves is 

 about 7 m (23 ft). 



(2) Fringe mangrove forests - man- 

 groves form a relatively thin fringe along 

 waterways. Zonation is typically as de- 

 scribed by Davis (1940) (see discussion in 

 section 3.2). These forests are best 

 defined along shorelines whose elevations 

 are higher than mean high tide. Maximum 

 height of the mangroves is about 10 m (32 

 ft). 



(3) Riverine mangrove forests - this 

 community type includes the tall flood 

 plain forests along flowing waters such as 

 tidal rivers and creeks. Although a shal- 

 low berm often exists along the creek 

 bank, the entire forest is usually flushed 

 by daily tides. All three species of 

 mangroves are present, but red mangroves 

 (with noticeably few, short prop roots) 

 predominate. Mangroves may reach heights 

 of 18 to 20 m (60 to 65 ft). 



(4) Basin mangrove forests - these 

 forests occur inland in depressions chan- 

 neling terrestrial runoff toward the 

 coast. Close to the coast they are in- 

 fluenced by daily tides and are usually 

 dominated by red mangroves. Moving in- 

 land, the tidal influence lessens and 

 dominance shifts to black and white man- 

 groves. Trees may reach 15 m (49 ft) in 

 height. 



(5) Hammock forests - hammock man- 

 grove communities are similar to the basin 

 type except that they occur on ground that 

 is slightly elevated (5 to 10 cm or 2 to 4 

 inches) relative to surrounding areas. 



