Composição florística e análise estrutural da floresta primária de terra firme na bacia do rio cuieiras, Manaus-Am

Abstract

This study dealt with vegetation characterization and horizontal structure analysis of a plant species community, and it was carried out at ZF-2 Tropical Forestry Experimental Station of the National Institute for Research in the Amazon (INPA). The climate is characterized as “Amw”, which means warm and humid all year long. Floristic and phytosociologic surveys were done over two transects (East-West and North-South) measuring 20 x 2500 m each, which were stratified by plateau and “baixio”. Each transect was divided into 125 sample units of 20 x 20 m each, where botanical samples were collected for identification besides information related to diameter at breast height (dbh) of 10 cm. For this study only plateau and “baixio” were used for further comparisons, therefore, 7 hectares were used instead of 10 ha of the two transects together. The floristic composition of the 7-ha (plateau + “baixio”) site is represented by 737 species, 238 genera and 59 botanical families. The richest families in terms of species are: Sapotaceae (69 species), Chrysobalanaceae (44), Lauraceae (44), Lecythidaceae (39), Fabaceae (39) and Mimosaceae (38). In terms of individual species, the most important are: Oenocarpus bataua Mart., Eschweilera wachenheimii (Benoist) Sandwith, Eperua glabriflora (Ducke) R.S. Cowan, Hevea guianensis Aubl., and Scleronema micranthum Ducke. The floristic composition in plateau is represented by 533 species, 187 genera and 53 families with 623 individuals per hectare and basal area equivalent to 28.3 m2ha-1. The richest families in plateau are: Sapotaceae (61 species), Lecythidaceae (36) and Burseraceae (27). The three most important families are: Lecythidaceae, Sapotaceae and Fabaceae. The most important species are: Eschweilera wachenheimii (Benoist) Sandwith, Eschweilera truncata A.C. Sm., Micrandropsis scleroxylon W.Rodr., Eschweilera coriacea (DC.) Mart. ex Berg. and Eschweilera pseudodecolorans S.A. Mori. The floristic composition in “baixio” is represented by 461 species, 177 genera and 50 families with 624 individuals per hectare and basal area equivalent to 29.1 m2ha-1. The richest families in “baixio” are: Sapotaceae (37 species), Fabaceae (33) and Chrysobalanaceae (28). The two most important families are: Arecaceae and Euphorbiaceae. The most important species are: Oenocarpus bataua Mart., Eperua glabriflora (Ducke) R.S. Cowan, Micrandra siphonioides Benth. and Vitex sprucei Briq.. In terms of occurrence exclusivity, plateau presented 9 families, 60 genera and 281 species, while “baixio” presented 6 families, 54 genera and 212 species.