Page 8, April, 1984, PALMETTO This is the fourth in a series of articles accumulations of sand, marl, and canopy, and within about 25 years, describing the Natural Communities defined organic debris. The bare white rock Pine Rockland develops into by the FloridaNatural Areas Inventory (FNAI). This classification system must be viewed as a usually creates a very harsh, dry Rockland Hammock. system of mental constructs imposed upon an environment, but during the wet Typical Pine Rockland shrubs include saw palmetto (Serenoa infinite variety of growing, changing, season pockets fill with water and intergrading, natural environments. Hence, humidify the environment. On some repens), roughvelvetseed (Guettarda more often than not, a given site will not precisely fit the classic description of the sites there may even be surface flow scabra), myrsine (Myrsine floridana), for a month or two each year. appropriatenatural community. Bypracticing poisonwood (Metopium toxiferum), wax myrtle (Myrica cerifera), comparing these descriptions to vegetation FNAI recognizes three types of observed in the field, an interested naturalist blackbead (Pithecellobium Pine Rockland, all dominated by should be able to learn to identify plant South Florida slash pine (Pinus guadalupense), long-stalked stopper communities accurately and contribute valuable site information to conservation elliottii var. densa). Keys Pine (Psidium longipes), pineland efforts. Rockland has an understory of *silver snowberry (Chiococca pinetorum), varnish leaf (Dodonaea viscosa), by Linda Conway Duever palm (Coccothrinax argentata), * brittle thatch palm (Thrinax tetrazygia (Tetrazygia bicolor), PINE ROCKLAND microcarpa), and tropical shrubs. locustberry (Byrsonima cuneata), Pine Rocklands occur in southeast Dade Pine Rocklandshave a shrubby cockspur (Pisonia rotundata), Florida on outcrops of Miami oolite tropical understory characterized by marlberry (Ardisia escalloniodes), sweet acacia (Acacia pinetorum), limestone. The ground surface is an extraordinary number of endemic typically dissected and solution- species. Temperate species make up black torch (Erithalis fruticosa), pitted, often to the point the jagged the bulk of the understory in Big rhacoma (Crossopetalumrhacoma), surface is termed "pinnacle rock." CypressPine Rockland. bustic (Dipholis salicifolia), and These communities have no real soils. All of these are fire-maintained indigoberry (Randia acu/eata). Smaller plants include corky- The tree roots push into crevices in communities which normally burn the rock and seek nutrients in small every three to ten years. Without fire, stemmed passionflower (Passiflora suberosa), coontie (Zamia pumila), hardwoods rapidly grow up into the yellowroot (Morinda royoc), piriqueta (Piriqueta caroliniana), pineland allamanda (Angadenia ~ ~ 6 berterii), diamond flower (Hedyotis nigricans), bracken (Pteridium aquilinum), Everglades musky mint (Hyptis alata var. stenophylla), Everglades partridge pea (Cassia ~ deeringiana), gopher apple (Licania ,- - :.::J""h~ -= =.-==- ,..~ -~~==~~ ~ - .:~ =--~--=--=~ -=~~ --=-- =--~ -~- ~ ~ = ~--~-..:.- ~ ~~= - - - --- ~ ~ - r "'--"""-., '"-'-'-- ~ "-' --- "".;;-., ,-\ ~~~~~~ ~ Co :/llilt .- ;.: i ~ . ~~ c. ~ ?' . ~1 ,~ . ...~~ ~ ~ ~ c.;:. :- 1 .;;: .' .". , ~ ~ . ~ . :. .., I,' . " ., ~ - .-'A."- ~ ~ ...".~. \ ~, ~ '. ... , , " :'; : 00 . ~ J' I . ..(... , .-., i_: '.."\ 0/0 , .~ r-.. -:I . ./ JI - ,. :. ~~ I' .' :.." . / I '. ,'/ J"..7 .'. I " ' ~ ,.J-.. :. , .J ~-. ;". , ~- " -10-- r ,,' ~ PALMEno, April, 1984, Page 9 michauxii), pineland croton (Croton *slender queen's delight (Stillingia the rare and endemic species. Some linearis), Galactia spp., large-flower sylvatica ssp. tenuis). species are found only in the Miami polygala (Polygala grandiflora), pine Rare species which occur in Pine area and much of the critical pink (Bletia purpurea), Bahama senna Rockland as well as in other pineland habitat of the endangered (Cassia bahamensis), and pineland communities include: * Bahama Key deer lies outside the Big Pine brake (Pteris longifolia), and pine- sachsia (Sachsia bahamensis), * little refuge. land fern (Anemia adiantifolia). strongback (Bourreria cassinifolia), ROCKLAND HAMMOCK Prominent grasses are wiregrasses * beach creeper (Ernodea littoralis), Hardwood forest "hammocks" (Aristida spp.), pineland broomsedge *coastal vervain (Verbena maritima), develop on rocklands protected from t (Andropogon cabanisii), Schizachy- *white ironwood (Hypelate trifoli- fire. They may grow on virtually bare 11 rium semiberbe, and lopsided Indian ata), small-flowered lily-thorn rock, with roots entwined around boulders and reaching into crevices ~; grass (Sorghastrum secundum). (Catesbaea parviflora), holly-leaf The following species are endemic rhacoma (Crossopetalum ilicifolium), for nourishment, but extended periods without fire can allow the to Pine Rocklands: *Blodgett's wild Big *necklacepod (Sophora mercury (Argythamnia blodgettii), tomentosa), and Krug's holly (Ilex accumulation of several inches of organic soil. In South Florida suitable Brickellia mosieri, tragia (Tragia krugiana). saxicola), Everglades painted leaf The remaining privately owned upland sites are usually islands (Poinsettia pinetorum), and Pine tracts of Pine Rockland are in the surrounded by water or wetlands. partridge pea (Cassia keyensis), Miami and Big Pine Key areas where Sometimes a slightly lower "moat" Chamaesyce conferta, * C. deltoidea they are severely threatened by rapid encircles the island, giving it an var. adhaerens, *wedge spurge (C. residential development. There are additional buffer. (Scientists deltoidea var. deltoidea), *Garber's extensive areas of Pine Rockland speculate that these features are the spurge (C. garberi), C. pinetorum, protected in Everglades National result of a combination of factors * Porter's hairy-podded spurge (C. Park, Big Cypress National Preserve, including windthrow of peripheral porteriana var. keyensis), Porter's and the National Key Deer Refuge, trees, erosion by surface flows broom spurge (C. porteriana var. but these habitats are not ideal for all diverted by the hammock, reduced periphyton growth and marl scoparia), *pineland jacquemontia (Jacquemontia curtissii) , * Dichrom- .,"'-". , accumulation at the shady forest margin, and perhaps more rapid ena floridensis, *sand flax (Linum ,./ ."" .-,J. "'.,' .. .. arenicola), *tiny polygala (Polygala .:., '~.": " y;-. .,f dissolution of the limestone due to smallii), *Digitaria pauciflora, . ...7:.:,.::::".' -- '.":'.'1 ; acidic runoff.) Although hammocks *pineland milk pea (Galactia ",.-.:., I do not normally flood, they are pinetorum), Galactia smallii, ., :.!_-- ... '.~. dependent upon high water tables to * Tephrosia angustissima, * Florida ,.,. .-. keep their wetland firebreaks rl~m~ rlrass I TriDascumfloridanum\. effective and to maintain reservoirs in solution features to keep interior humidity high and temperatures moderate. The hammock's dense domed canopy is also critical to the interior microclimate. It not only fends off desiccating winds and frost, but it deflects storm winds and prevents extensive structural damage during hurricanes. There are Temperate Rockland Hammocks dominated by live oak (Quercus virginiana) and laurel oak (Q. hemisphaerica) in North Florida, especially in the Gainesville and Brooksville areas, but the classic isolated islands of tropical vegetation are found primarily in the Miami area, the Everglades, and the Keys. FNAI recognizes five different types in this part of the state. The Miami hammocks where live oak is mixed with tropical species are Miami Ridge Hammock. The tall forests of Jamaica dogwood (Piscidia piscipu/a), mahogany (Swietenia mahagoni), gumbo limbo (Bursera simaruba), wild tamarind (Lysiloma latisiliqua), and other tropicals in the Upper Keys continued next page I'dgt' 10, April, 1.,114,t'ALMt ITO ZIJzYJ!,iunl). ilnu spicewo()u many ecotones between communi- ties are simply vague boundaries ,Ire Keys Hammock lort'~(. (Calyptrclnthe.~ pallens). Coontie The lower Keys' shorter (Zamia pumila), yellowroot (Morinda where species from the two mix, this "scrubbier" forest of Jamaica royoc), dildo cactus (Cereus one is a distinct community with dogwood with poisonwood pentagonus), The/ypteris kunthii, species of its own. Salt spray, wind, Oplismenus hirtellus, Lasiacis and occasional inundation by storm (Metopium toxiferum), seagrape (Coccoloba uvifera), *brittle thatch divaricata, and Oichanthelium tides make this too severe an palm, etc., is Keys Hammock Thicket. commutatum are likely understory environment for a forest to develop, If this is a sparse shrub community species. but the marine influences are not so with cacti and other spiny, xerophytic Epiphytes may be abundant. Most extreme as to altogether prohibit plants, it is considered Thorn Scrub. If common are resurrection fern terrestrial vegetation. The result is an it is a well-developed hardwood (Polypodium polypodioides), open rocky flat with stunted shrubs, forest with an understory of cacti and needle-leaved airplant (Tillandsia succulents, and sparse herbaceous agave and perhaps a few emergent setacea), soif-leaved wild pine plants rooted here and there in (Tillandsia va/enzue/ana), and crevices and mounds of debris. *tree cacti (Cereus robinii), it is classified as Cactus Hammock. The butterfly orchid (Encyclia tampensis). Littoral Rock Pavement is a technical East Everglades, Pinecrest, and long Rare Rockland Hammock plants term which has been used for similar