Features and conservation of the Brazilian Pantanal wetland

Abstract

The Pantanal is a 140,000 km² sedimentary floodplain in western Brazil and one of the largest wetlands in the world. The main landscapes and phytophysiognomies, according to flood origin, are briefly described and some of the characteristic plant species are mentioned: (a) river flood (1–5 m) on clayey eutrophic soils with gallery forests, pioneer forests and scrub, Tabebuia and Copernicia parks, seasonal swamps, grasslands and oxbow lakes; and (b) rain flood (10–80 cm) mainly on dystrophic sandy soils (72% of the total area) with savanna (“cerrado”) grasslands and woodlands, with or without ponds. Regulating factors of the vegetation such as wet-and-dry cycle and management are considered. Dynamics of the vegetation, in particular the aquatic types, are shortly depicted. The role of grazing for conservation is discussed, and we suggest that 200 years of cattle ranching apparently did not cause major changes in the vegetation, except turning tall grass into short swards, as the domestic herd found a nearly empty niche. However, severe threats to the flora and fauna of the Pantanal originate outside the floodplain. Siltation of the Taquari river is pointed out as the worst environmental problem, changing the hydrology (wet-and-dry to wet), fauna and flora, e.g. eliminating riparian forest.