Characterization and utilization of varzea and terra firme forests in the Amazon estuary.

The várzea and terra firme forests of the Ilhas de Abaetetuha, in the Amazon estuary, were compared as to their utilization,forest structure,bíomass,and tree-ring characteristics.Várzea forests are inundated twice daily throughout the year. These forests have been altered heavily by human activities, especially through the management/cultivation of açaí palm (Euterpe oleracea Mart.). Both the number of trees and the number of tree species are limited due to human management and frequent inundations. Terra firme are also composed of secondary forests, but human impacts have been less and possess more tree species with a higher wood density than the várzea counterparts because latewoods are formed during the dry season. Without human intervention, the forest biomass of the várzea exceeds that of the terra firme. However; it is reduced to less than one-third when strongly disturbed. It was also found that the wood density was closely related to the brightness contrast between early and latewoods, and in general, the várzea species with a low wood density had a small brightness contrast