Central amazon floodplain forests: Root adaptations to prolonged flooding

The floodplains of Central Amazonia represent a complex system of inundated river valleys and shallow lakes along the Solimbes-Amazonas river, Which is subjected to an annual flood-pulse lasting up to 10 months. Such flooding reaching an amplitude of about ten meters causes dramatic changes in the bioavailability of nutrients and oxygen levels and poses extreme constraints for plant survival and reproductivity. Tree species of inundation forests in Central Amazonia had to evolve adaptive mechanisms to both desiccation of soils and partial or full submergence. To adapt to flooded conditions, some, trees overcome the flood period by dormancy accompanied by defoliation and formation of annual rings in the wood. Other species maintain metabolism and retain the foliage during the flooding, representing another adaptive mechanism to low oxygen availability. This investigation focused on the root physiology and morphology of six species typical of white-water inundation areas (varzea) led to a preliminary classification of adaptive strategies of trees inhabiting forest communities in floodplains of the Amazon basin