Estrutura da flora árborea em áreas de campinaranas (prístinas e em regeneração) do baixo Rio Negro

Abstract

The Amazonian campinaranas delimit an ecological region that encompasses different phytophysiognomies associated with sandy soils. They represent approximately 7% of the entire Amazon basin. They occur predominantly in the Negro River basin and are associated with the sandstone rocks of the Guiana Shield and Venezuela and are little known botanically. Therefore, this study aimed to analyze the tree structure of the pristine and regenerating campinaranas of the lower Rio Negro and their relationship with the soil structure. The study was carried out in areas close to the metropolitan region of the city of Manaus, lower Rio Negro, preferably in areas that had a pristine campinarana next to one in regeneration. Five non-continuous plots of 10x20m (0.1ha) were delimited per area, with 30 m of distance between them. All living woody tree flora (excluding lianas) standing or inclined with PAP (perimeter at breast height, or 1.3 m from the ground) >= 15 cm were sampled. For each sampled area, phytosociological parameters and multivariate analysis were calculated using the FITOPAC and PC-ORD programs. A total of 1,110 individuals were inventoried, distributed in 52 families and 219 tree species. Principal component analysis indicated coarse sand contents as the most informative in all collection sites. Canonical correspondence analysis explained the correlation between soil factors in silt and clay parameters. It is therefore concluded that the campinaranas areas of the lower Rio Negro have a relatively high floristic diversity and that, above all, the depth of the water table and the relationship between clay and coarse sand are determining factors for the composition of plant species.