Phytossociology in Floodplain Forest of the Amazon River Estuary in the Amapa State

Abstract

The present study was developed aiming to evaluate the variations in the structure and the dynamics of Amazonian estuarine floodplain forest, in three places (Bailique, Igarapé Fortaleza eandAracu River) along the north arm of the Amazon River, in two measurements. The samples were installed in areas of forest that had a good state of repair. In 2001/02 three permanent sample plots were installed with size of 100 m x 100 m, divided in ten sub-plots with 20 m x 50 m, and in 2006/07 a new measurement was done to evaluate the changes, with minimum inclusion CAP of 15 cm. The families number remained the same in the Bailique (20), in the igarapé Fortaleza (26) and had reduction in the Aracu river from 27 to 25 families; the species number reduced in the three places: 39 for 37, 49 for 48 and 50 for 47; the absolute density (trees per hectare) increased in the Bailique (17),
reduced in the Aracu river (50) and in the igarapé Fortaleza (151); the basal area (m2/ha) increased in the Bailique (1.97), in Aracu river (2.90) and reduced in the igarapé Fortaleza (5,64); the mixture quotient of Jentsch remained the same in the Aracu river (01:18), reduced in the Bailique (01:19 from 01:20) and increased in the igarapé Fortaleza (01:21 for 01:18); the biggest ingrowth occurred in the Bailique, with 31 açaí (Euterpe oleracea Mart.); the biggest  reductions occurred with the death of 33 murumuru (Astrocaryum murumuru Mart.) in the Aracuriver and 46 E. oleracea in the igarapé Fortaleza; the species of better sociological position in the forest was E.oleracea.