Análises estruturais e composição florística de um encrave de cerrado no intervalo de quatro anos (2019- 2023) na FLONA do Araripe-CE

Abstract

The cerrado represents the second-largest biome in Brazil. Although its core area is in the Brazilian Central Plateau, there are also peripheral areas or disjointed patches in the Northeast, Southeast, and South regions of Brazil. In the state of Ceará, we have the occurrence of cerrado sensu stricto (s.s) vegetation, located in the Chapada do Araripe. Fire is recognized as a significant factor that affects the structure and plant composition of tropical savannas, and its effect can alter the structure and floristic composition depending on its intensity. This study hypothesizes that the total absence of fire enables dynamic stability in the woody community of cerrado sensu stricto located in the Araripe National Forest. Therefore, our aim was to understand the behavior of the woody community in the cerrado s.s enclave in the absence of fire over a four-year interval. Structural analysis and vegetation composition were conducted by comparing two surveys, one conducted in 2019 (T0) and another in 2023 (T1). Sampling was performed through 50 subplots of 10x10m, totaling a sample area of 0.5 ha. All stems of tree individuals with a diameter ≥ 5 cm measured 30 cm above the ground were measured in accordance with the DryFlor Plot Protocol. The occurrence of fire in the area was verified through satellite images. Phytosociological parameters were obtained using the FITOPAC 2.0 program, and diversity parameters using PAST v.4.03. To check for differences in means of abundance, basal area, and absolute density, paired-sample t-tests with bootstrapping were performed in R v.4.3.1. The species Hirtella ciliata Mart. & Zucc, Caryocar coriaceum Wittm, and Parkia platycephala Benth were the most important at T0 and T1. Structural parameter differences were not significantly different over time. Diameter class distributions in the two surveys form a curve similar to an "inverted J." The Shannon-Wiener diversity index (H') was 2.82 at T0 and 2.78 at T1, with evenness (J') being 0.802 and 0.801, respectively. The analyses presented in this study indicate that the woody community located in the cerrado s.s enclave in the Araripe National Forest remained stable over the analyzed period, showing no tendency to transition to cerradão. Therefore, continued studies of the area, combined with obtaining abiotic data, are necessary to verify whether the findings in this work will persist in the coming years or if there will be changes in the woody community.