Diversity in some tropical wetland systems of South America

NEIFF, J.J.

Biodiversity in wetlands: assessment, function and conservation

Backhuys

Lugar: Leiden; Año: 2001; p. 157 - 186

Large wetlands in South América constitute complex systems that generally include various ecosystems. For this reason, it is necessary to consider them as macrosystems composed of permanent and seasonal wetlands, and also sections of upland habitat. Two well-defined families of large fresh water wetlands: Water-logged or "pantanales" and River floodplains (alluvial wetlands) were classified in nine types of wetlands in order to compare it functioning and diversity patterns. Hydrologic and fire pulses are analyzed as a power factors on the biotic complexity. Species richness are discussed in relation to the longituninal and transversal gradients in a floodplains of rivers. The species richness or diversity should be used as a synthetic attribute of the complexity of wetlands when it are reffered to the tyme and space scales. The number of species present in a determined place and moment is always much lower than the number of expected species, specially in the floodplains due to the hydrological fluctuation regime of the wetlands themselves. The species richness is reflected in part by the elasticity quotient, which is a measure easy to obtain. The highest species richness was registered in wetlands with an elasticity coefficient lower than 4 and higher than 1. The other necessary condition is to know the turnover of the species in the system, because many wetlands have a relatively constant value of complexity (expressed as number of species or any of the indices of specific diversity), although there is a high qualitative renovation of the system elements. It is convenient to remember that wetlands have a variability regime very different from the aquatic systems and from those of the mainland, so that the richness values and/or of biodiversity could have a different significance. Systems with a low number of species could be very stable and viceversa. Because of this, diversity as an expression of functional complexity could be studied advantageously with indices which allow to reflect the fluxes (information in the wide sense) which go through the system.