Abstract

GORDON, Elizabeth. Dinámica de la vegetación y del banco de semillas en un humedal herbáceo lacustrino (Venezuela). Rev. biol. trop [online]. 2000, vol.48, n.1, pp.25-42. ISSN 0034-7744.

Vegetation and seed banks association with seasonal water depth variations were studied in a herbaceous wetland of a tropical lake in Monagas, Venezuela. The sampling was done in 10x10m² quadrates located at random in two zones of the lagoon. In each sampling four quadrates per zone were analyzed for relative species density, species richness, life forms and water depth. Soil samples were taken simultaneously for ize and composition of the seed banks (seedling emergence method). Soil pH was five. The organic total fraction of the soil varied between 38% and 52%, and the conductivity between 114 and 182 µmhos/cm. 50 species were recorded: 46% perennial herbs, 22% vines, 12% suffrutescents and 10% hydrophytes. The highest species richness was recorded during periods of rain and rain-dry transition. Hymenachne amplexicaulis, Leersia hexandra, Sacciolepis striata and Polygonum acuminatum were among the most important species numerically. The total density of seed bank varied between 5689 and 13936 seedlings/m². In the seed bank there were 58 species: 43% perennial herbs, 22% suffrutescents, 12% vines 9% annual herbs and 9%, hydrophytes. The highest species richness in the seed bank was during periods of dry and dry-rain transition. Cyperus odoratus, Eleocharis interstincta, Ludwigia hyssopifolia, L. lithospermifolia and Polygonum acuminatum had the highest densities.  The potential flora of these wetlands included 76 species, but only 33 (43%) were common to the seed bank and the vegetation.

Keywords : Vegetation; seed bank; wetlands; lagoons; tropical; Venezuela.