Figure 16 presents a generalized 

 scheme of plant community succes- 

 sional relationships in the study 

 area. Common and scientific names 



of flora discussed throughout this 

 paper are based on the comprehensive 

 treatise by Long and Lakela (1971). 



_». High, moist locations 

 ( 1 imestone or sand) 



_». Pinus ell iotti forests 



11 



rtti I 



It 



-*. Pine-hardwood forests 



.Regional drying, fire control, 

 exotic invasions 



-*. Cypress-hardwood 



swamps 



tl 



-♦Cypress heads, sloughs, 

 strands 



It 



Sawgrass glades, 

 ~**related prairies 



ti 



Climatic climax 



Temperate hardwoods 

 _ in north _ 



Tropical hardwoods 



in south 



11 



Bay heads, 

 Palm islands 



Sea level fluctuation 



High, dry locations 

 (sand dunes, beaches, "*"" 

 middens) 



U 



Pinus clausa forests ■<- 



it 



Pine-Oak forests -*- 



Regional drying, fire control 

 exotic invasions 



Lowland hardwood forests^_ 

 tree i slands 



Mangroves, salt marshes- 

 salt barrens 



II 



Brackish water 



Figure 46. Summary diagram of successional relationships among south Florida 

 vegetation communities (adapted from Alexander and Crook 1973). 



6.11 PINELANDS 



The pinelands of the study area 

 are conspicuously associated with 

 outcroppings of the Atlantic Coastal 

 Ridge. Soil development here is 

 extremely poor. The substrate is 

 the solution riddled oolitic facies 

 of the Miami Limestone. The domi- 

 nant species is Caribbean slash pine 

 ( Pinus elliottii var. densa ) . Saw 

 palmetto ( Serenoa repens ), wax myr- 

 tle ( Myrica cerifera ), varnish leaf 

 ( Dodonaea viscosa ), and velvetseed 

 ( Guettarda elliptica ) are common 

 in the understory (Olmstead et al. 

 1980). 



Pinelands are a fire arrested 

 climax community. Without periodic 

 fire, the pines are gradually 

 out-competed by tropical hardwood 

 species. The relatively open under- 

 story, the accumulation of pine- 



straw, and the open canopy of the 

 pines encourages the initiation and 

 spread of fire. Slash pine seed- 

 lings require stimulation by fire in 

 order to germinate, while the thick, 

 moist bark of maturing trees often 

 protects them from consumption by 

 milder fires. Seedlings and saplings 

 of encroaching hardwoods tend to be 

 destroyed or at least held in check 

 by fire. 



Without fire, however, the 

 competitive edge tips in favor of 

 tropical hardwood hammocks. Mature 

 slash pine are highly susceptible to 

 disease and without the germinating 

 stimulus of fire, young saplings do 

 not replace them. The relatively 

 closed canopy of the tropical hard- 

 wood hammock tends to conserve more 

 moisture and quickly recycle forest 

 floor litter, thus discouraging fur- 

 ther fires. 



Ill 



