Beach dune/strand 



The beach dune-strand habitat 

 consists of characteristic shore and 

 nearshore grassy and herbaceous 

 plants, or thicket forests of shrubs 

 and small trees (Davis 1942, 1943). 

 The vegetation flourishes on coarse 

 calcareous sands, rocks, and shell/ 

 coral rubble mounds. As a communi- 

 ty, it is best represented on the 

 seaward side of several middle Keys 

 (e.g., Bahia Honda and Long Keys) 

 and the distal islands (Multer 

 1977). Davis (1942) identified four 

 (4) vegetative zones which occur 

 from the beach inland. These in- 

 clude: (1) the pioneer beach strand; 

 (2) the dune strand; (3) the transi- 

 tion zone; and (4) the hammock 

 strand. 



The pioneer beach strand exists 

 from the wave line on the beaches to 

 the higher parts of the fore dunes, 

 definitely above the usual effects 

 of mean high water. Its flora 



consists of a number of pioneer 

 halophytic species that can spread 

 out over the upper beach, take root 

 and germinate from seeds rapidly, 

 and tolerate occasional wave action 

 and sand movement. Commonly found 

 species include sea purslane ( Sesu - 

 vium portulacastrum ) , sea rocket 

 ( Cakile fusiformis ), beach morning 

 glory ( Ipomoea pes-caprae var. 

 emarginata ) , beach grass ( Panicum 

 amarulum ) , rush grass ( Sporobolus 

 virginicus ) , sea oat ( Uniola panicu - 

 lata ) , spurge ( Chamaesyce mesembry - 

 anthemifola ) , and sea lavender 

 ( Tournefortia qnaphalodes ) . The 



most halophytic of the beach dune- 

 strands species exist in this first 

 zone where even the upper beach 

 plants must tolerate occasional 

 saltwater submergence. The two more 

 common species in this zone, sea oat 

 ( Uniola sp.) and spurge ( Chamaes - 

 yce ) , also serve as the dominants in 

 the more inland dune-strand com- 

 munity. The pioneer beach strand 

 zonation does not develop along the 



narrower beaches where the dune 

 terraces meet or are very close to 

 the upper reaches of high tide 

 (Davis 1942). As Davis (1943) not- 

 ed, when the pioneer beach strand is 

 developed, aggradation of the breach 

 is indicated as these plants are the 

 first to grow on newly built-up sand 

 areas. 



Further inland, the dune-strand 

 zonation is the most commonly obser- 

 ved and distinctly delineated of the 

 strand communities. This zone usu- 

 ally appears as the first of three 

 possible zonations on an elevated, 

 almost flat, platform of dunes. 

 They are approximately 22.9 to 137.2 

 m (25 to 150 yds) wide and from 0.3 

 to 2.7 m ( 1 to 9 ft) above mean 

 high tide. A wave cut terrace gen- 

 erally forms the seaward boundary 

 and if the dune platform's width 

 exceeds approximately 68.6 meters 

 (75 yds), then all three zonations 

 (dune-strand, shrub-strand, ham- 

 mock-strand) may develop. If nar- 

 rower than 68.6 m (75 yds) then the 

 platform is nearly always covered by 

 the dune-strand community (Davis 

 1942). Predominantly herbaceous, 

 the dune-strand commonly includes 

 the grasses sea oat ( Uniola panicu - 

 lata ) , spurge ( Chamarsyce mesembry - 

 anthemfolia ) , Waltheria indica , a 



number of leguminous plants, the 

 spider lily ( Hymenocallis latifo- 

 lia) , and the shrubs sea lavender 

 ( Tourenfortia qnaphalodes ) and bay 

 cedar ( Suriana maritima ). Where 



shrubs are scattered over the plat- 

 form area the dune-strand community 

 is considered unaltered, but if a 

 definite increase in shrub density 

 occurs, covering more of the area 

 than herbaceous plants, then a 

 scrub-strand community is recognized 

 (Davis 1942). 



The scrub-strand community is 

 generally the transition zone be- 

 tween the dune-strands zone and the 

 hammock forest. On most of the 



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