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Abstract:
The Amazon River and its large tributaries are accompanied along their middle and lower courses by large fringing floodplains which cover an area of about 300 000 km2 (Sect. 1.5). Their local names are: “várzea” and “igapó”. These terms have been adopted in scientific literature, but until now they have not been defined. On the basis of hydrochemical investigations, Sioli (1950, 1951, 1956, 1965a, 1968) used the term várzea for floodplains along white-water rivers, which are rich in nutrients and suspended matter, and igapó for those along black-water rivers, which are poor in both. This nomenclature is supported by the zoological and botanical investigations of Irmler (1977) and Prance (1979), and it will be adopted here as well. The term “floodplain” will be used when referring to the general category. The periodically flooded várzea and igapó are contrasted with the upland that is not flooded, referred to as the “terra firme”. The transition between flooded and nonflooded areas can be very abrupt, being formed by steep bluffs as high as 100 m.
