Comparison of pollen distribution patterns in surface sediments of a Colombian Caribbean mangrove with geomorphology and vegetation

Distribution patterns of mangrove pollen taxa in recent surface sediments of the lagoon system of Cispatá are compared with geomorphological and vegetational patterns. The pollen spectra of 51 samples show the floral composition and structure of mangrove stands in three main geomorphic units in the study area. The oldest mangrove stands, with the highest tree mean diameter at breast height and total height, are represented in the pollen spectra by the highest mean percentages (> 65%) mainly Rhizophora mangle. The area with estuarine conditions shows, mean mangrove pollen percentages between 35 and 50% reflecting the mangrove colonization process since 1930, as well as current anthropogenic disturbance. Lowest proportions of mangrove pollen (< 25%) are found in the foothills, reflecting high disturbance of mangroves and the transition from mangroves to terra firme forest. Distribution patterns of the pollen and spores indicate that water transport is more important than wind transport over short distance and reflect local vegetation. Fern spores and pollen grains of secondary forest taxa and grasslands are widely distributed and reflect regional vegetation. Rhizophora pollen proportions reflect its relative abundance in the forest stands. Even low proportions of Avicennia pollen indicate this species’ dominance in sparse stands and saline back swamp conditions. Conocarpus presence provides evidence of supratidal location of stands. An inverse relationship between proportions of Laguncularia pollen and Acrostichum spores demonstrates successional processes triggered by anthropogenic disturbance. This is the first report on pollen in surface sediments in the Colombian Caribbean. As such, the data should prove valuable in efforts to apply interpretations of marine records to reconstruct past environmental and climate changes in the Caribbean.