FLORISTIC COMPOSITION AND DIVERSITY IN TERRA FIRME FOREST UNDER WATER STRESS IN THE AMAZON

The studies on floristic composition are an aid in the understanding of the structure and dynamics of the plant communities, fundamental parameters for its management and conservation. Thus, the objective of this work was to evaluate the floristic composition, richness, diversity and models of species abundance over a 10-year period (2005 to 2015) in two terra firme forest areas, with and without water deficit in the soil. Data were collected in 98 subplots denominated A (control) and 98 subplots B (rainwater exclusion), each measuring 10 m x 10 m, of which all plant species with diameter at breast height (DBH≥10 cm) were listed. The Fabaceae (33), Sapotaceae (27), Chrysobalanaceae (15), Burseraceae (13) families were the most representative in the study areas, especially Fabaceae, which showed the highest richness. A small variation was found in the observed richness in subplots A, and the community evenness and the diversity index remained constant, while in subplots B, the variation in richness was greater, which may have contributed to a small change in the diversity index over time. The best ecological models adjusted were Zipf and Zipf-Mandelbrot for the plant communities of subplots A and B, respectively, which are interpreted as the successional process in which late colonizing species have the greatest needs for a specialized niche and have a high ecological cost of energy, time and ecosystem organization before their establishment. Thus, it can be inferred that water deficiency in the soil did not significantly affect the conservation of the forest under study.