Wetlands of tropical South America

Abstract

The climate of tropical South America is characterized over large areas by a high annual precipitation, varying from 1000mm to >5000mm per year. A pronounced seasonality in rainfall results in the periodic flooding of large areas covered by forests or savanna vegetation. Most wetlands belong to the category of seasonal wetlands with a pronounced dry period. The floodpulse is monomodal and predictable in the savannas and the fringing floodplains along the large rivers whereas it is polymodal and unpredictable in the floodplains along small streams. Plants and animals respond to this pulsing with a large set of morphological, anatomical, physiological, and ethological adaptations. Nutrient status of the wetlands varies from extremely low levels in areas flooded by nutrient-poor water (from rains or black water rivers) to high levels in the fringing floodplains of white water rivers, rich in fertile sediments. Productivity varies from low to very high, reaching maximum values up to 100 t dry material per hectare per year in the floodplain of the Amazon River. There is a complex exchange of nutrients and energy between the terrestrial and the aquatic phase and between the floodplains and the connected river systems. Further wetland types occur mainly along the coast of the Atlantic ocean, partly in the form of mangroves or salt marshes. Peat bogs, cushion bogs, and reed swamps occur in the wet Paramos of the high Andes, salt pans occur in the dry Puna. -from Author