Estrutura e diversidade florística da savana amapaense são influenciadas pelo gradiente ambiental

Abstract

The Brazilian savanna, consisting of a heterogeneous mosaic of plant formations, occupies approximately 23% of Brazilian territory. Its vegetation encompasses a wide variety of physiognomic features, alternating between savanna, grassland, and forest formations. In the Amazon, the savanna zones, also known as Amazonian savannas, are distributed across the states of Amapá, Amazonas, Pará, and Roraima, and despite being considered one of the 25 critical areas for biodiversity conservation in the world, the savanna has been the target of few concrete actions and few studies aimed at its conservation. The savannah area of the state of Amapá is the second largest continuous area of savannah in the Amazon, second only to the areas of the state of Roraima. Studies focused on the structural composition and floristic diversity of its vegetation are important to guide the definition of priority areas for their conservation, and to support the planning of actions in the restoration of degraded environments. The present study, mostly conducted in permanent plots, was grouped according to site characteristics into five groups: a) G1 plots 04, 07, 08 and 15; b) G2 plots 05, 09, 18 and 19; c) G3 plots 03, 16 and 20; d) G4 plots 01, 02, 11, 12 and 13; e) G5 plots 06, 10, 14 and 17 The objective was to evaluate the structure and floristic diversity of the tree and shrubby-arboreal in the Amapá savanna, seeking to answer the following question: The floristic composition and shrubby-arboreal structure of the Amapá savannas vary significantly among the different sample groups, reflecting the influence of a regional environmental gradient? As results we have, especially in group G1, the species Ouratea racemiformis Ule, Curatella americana L e Byrsonima crassifolia (L.) Kunth showed significant association with the floristic gradients revealed by NMDS in the dissimilarity of the floristic-structural pattern. On the other hand, group G4 stood out for being isolated in the ordination space, possibly related to more structured or conserved vegetation, while groups G2, G3 and G5 showed overlap and dispersion, indicating floristic transition or similarity between them. Rarefaction analysis (Hill, q = 0) revealed differences in species richness between the groups, in which G1 presented the highest observed richness (21 species), G3 and G4 intermediate richness (17 and 14 species), G2 and G5 presented the lowest observed richness (11 species). Overall, the result of this study aims to contribute with information on the structural composition and floristic diversity of the shrubby-arboreal vegetation in the savanna areas of Amapá.