distal islands, the hammock forest 

 is absent and the scrub-strand com- 

 munity occupies the entire inner 

 zone of the dune platform. Of the 

 more common shrubs, bay cedar ( Suri- 

 ana maritima ) is the most typical 

 followed by lantana ( Lantana involu - 

 crata ), gray nicker ( Caesalpinia 

 crista ) , night-shade ( Solanum 



bahamense ) , sea ox-eye ( Borrichia 

 arboresens ) , and prickly pear ( Opun - 

 tia stricta var. dillenii ) ♦ The 



open areas between the thickets of 

 scrub plants contain a number of 

 dune strand species. Generally a 

 few hammock plants such as joewood 

 ( Jacquinia keyensis ), silver palm 

 ( Coccothrinax arqentata ), and black- 

 bead ( Pithelobium keyense ) are often 

 present. Governed by xeric condi- 

 tions the scrub-strand represents 

 the middle ground between the more 

 halic soils of the fore dune commu- 

 nity and the more mesic hammock 

 strand associes. Also, as xeric 



implies, this zonation represents 

 the lowest soil moisture condition 

 resulting from the relative eleva- 

 tion and the highly porous, coarse 

 calcareous sands. As humus accumu- 

 lates farther inland the soil 

 moisture content increases, at least 

 surficially, promoting the coloni- 

 zation of hammock strand species 

 (Davis 1942). 



The last and most inland of the 

 strand communities is the hammock 

 strand forest. This community 



seldom develops fully on the distal 

 islands and is primarily restricted 

 to a few of the main keys (e.g.. 

 Long Key). Also called thicket 



forests, these communities are pri- 

 marily composed of small trees, 

 although some taller ones may exceed 

 9.1 m (30 ft). The more common and 

 significant hammock-strand species 

 include cats claw ( Pithecellobium 

 unquis-cati ) , joewood ( Jacquinia 

 keyensis ), silver palm (Coccothrinax 



arqentata ) , brittle thatch ( Thrinax 

 microcarpa ) , thatch ( T. parviflora ) , 

 poisonwood ( Metopium toxiferum ), red 

 ironwood ( Reynosia septetrionalis ), 

 caper tree ( Capparis flexuousa ), 

 white stopper ( Eugenia axillaris ), 

 Spanish stopper ( Eugenia myrtoides ), 

 beef tree ( Pisonia discolor var. 

 discolor and var. lonqifolia ) , and 

 shell orchid ( Encyclia tampensis ). 

 As mentioned previously, the strand 

 communities develop on calcareous 

 sand, marl, and rocky substrates. 

 When the hammock-strand occurs on 

 rocky soils the plants are dwarfed, 

 scrubby and widely spaced like those 

 of the scrub-strand community. Al- 

 though species composition is simi- 

 lar for all three substrates, some 

 plants, including prickly pear 

 ( Opuntia stricta var. dillenii ) , 

 wild cotton ( Gossypium hirsutum ), 

 saffron plum ( Bumelia celastrina 

 var. augustifolia ) , molina ( Maytenus 

 phyllanthoides ) , cats claw ( Pithe - 

 cellobium unquis-cati ), and geiger 

 tree ( Cordia sebestena ), are more 

 typical of rock hammocks and marl 

 soils than of sand hammocks. 



9.22 INTERTIDAL/SHORELINE 

 HABITATS 



Exposed, Vertical Rocky Shores 

 and Seawalls 



This habitat is both naturally 

 occuring and a by-product of man's 

 activities in the Florida Keys. 

 Natural habitats occur along steep 

 scarps in the limestone bedrock that 

 form as a result of erosion (solu- 

 tional and abrasive) from relatively 

 high wave energy (e.g., Vaca Key). 

 These generally provide little or no 

 residual sediments to the intertidal 

 zone (Stephenson and Stephenson 

 1950, Ginsburg 1953b, Getter et al. 

 1981) Man-made habitats include 

 concrete or tightly cemented 

 seawalls, and the structural sup- 

 ports for bridges and piers. These 



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