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

ABSTRACT 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, species richness, Shannon’s 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 plants species with diameter at breast height (DBH≥10 cm) were listed. The Fabaceae (33), Sapotaceae (27), Chrysobalanaceae (15) and Burseraceae (13) families were the most representated in the study areas. A small decrease was found in the observed species richness in area A, but the community evenness and the Shannon diversity index remained constant, and a small increase was found in the observed species richness in area B, which may have contributed to a increase in the diversity index over time. The Zipf and Zipf-Mandelbrot models adjusted for the plant communities of areas A and B, respectively, indicate that such areas indicate good ecological conditions for the establishment of late colonizing species. Thus, it can be inferred that water deficiency in the soil did not significantly affect the conservation of the forest under study.