VEGETATION ZONES AND DIAGNOSTIC POLLEN PROFILES OF A COASTAL PEAT SWAMP, BOCAS DEL TORO, PANAMA

A survey of the dominant vegetative cover of a large domed coastal swa mp near Changuinola in the Province of Bocas del Toro, Panama, has bee n undertaken as an initial step in reconstructing the Holocene history of peat accumulation on this coast. Seven phasic communities of peat- forming vegetation are defined and mapped: (1) Rhizophora mangle mangr ove swamp; (2) mixed back-mangrove swamp; (3) Raphia taedigera palm sw amp; (4) mixed forest swamp; (5) Campnosperma panamensis forest swamp; (6) Sawgrass +/- stunted forest swamp; (7) Myrica-Cyrilla bog-plain. Pollen extracted from surface peat samples and collected from dominant vegetation, at representative sites, is used to prepare a pollen prof ile of each phasic community. These profiles are then compared to poll en distribution in 2 peat cores, one from the deep central part of the deposit and the second from a site near the marine margin, in order t o construct a history, by floral succession, of the 4000 year evolutio n of the deposit. The Changuinola mire originated as freshwater palm a nd hardwood forest swamps that developed in close proximity to both th e Changuinola River mouth, probably behind a barrier bar and freshwate r lagoon system adjacent to a low energy, mangrove-dominated bay. The early swamp was likely drained to the southeast by brackish blackwater creeks much as it is today, and formerly extended considerably farthe r in the direction of Almirante Bay. The palm swamp was succeeded by h ardwood forest swamp dominated by a very limited number of specialized species, only one of which (Campnosperma panamensis) is prone to form ing monospecific stands. Increasing accumulation of woody peat promote d by the everwet climate impeded drainage of the mire, leading to domi ng, increased oligotrophy, and establishment of bog-plain conditions i n a manner similar to that described by the Anderson model of successi on in the coastal swamps of Malaysia and Indonesia. Development of the Changuinola mire did not require the initial mangrove phase which is common to the peat swamps of southeast Asia, as the palm Raphia taedig era is able to colonise and institute peat accumulation in a variety o f freshwater and brackish environments.