Regeneração natural em fragmentos de cerrado sensu stricto: padrões ecológicos e aspectos silviculturais de Eugenia involucrata como uma espécie-alvo

Abstract

The cerrado sensu stricto, formerly the most extensive phytophysiognomy of the Cerrado biome, has undergone intense conversion to agriculture and livestock production, resulting in fragmentation and varying levels of environmental disturbance. In this context, the present study aimed to characterize the structural patterns of the woody community, evaluete the natural regeneration potential in three fragments (F1, F2, and F3), analyze the regenerative status of Eugenia involucrata and investigate the initial growth and morphophysiological traits of its seedlings under nursery and experimental conditions. Natural regeneration was sampled in two plot classes: tem plots of 10 × 10 m (Class I) and tem plots of 2 × 2 m (Class II), arranged along transects perpendicular to the drainage line. For each species, density, frequency, and the Total Natural Regeneration index (RNT) were calculated, with RNT also determined separately for E. involucrata. A total of 501 regenerating individuals were recorded in F1, 321 in F2, and 153 in F3. The most conserved fragment (F1) exhibited greater species richness and density, with Fabaceae, Myrtaceae, and Malpighiaceae being the most prominent. In F2, Fabaceae, Myrtaceae, Chrysobalanaceae, and Connaraceae were most representative in Class I, while in F3, Fabaceae, Anacardiaceae, Annonaceae, Chrysobalanaceae, and Myrtaceae predominated across both classes. Species such as Miconia albicans, E. involucrata, Matayba guianensis, and Connarus suberosus showed the highest RNT values, indicating strong natural regeneration potential under contrasting environmental conditions. The occurrence of exclusive species across fragments highlighted environmental heterogeneity and differing responses to disturbance. E. involucrata accounted for 113 individuals across the three fragments, with significant differences in density and consistently high RNT values, confirming its robust regenerative performance. Early development of the species in the nursery was examined through two experiments. Experiment I (Matrix) used seeds from three mother trees originating from two fragments, resulting in three treatments (M1, M2, and M3). Height, stem diameter, leaf number, fresh and dry biomass of shoots and roots, MSPA/MSR ratio, Dickson Quality Index (DQI), leaf area, mesophyll structure, stomatal conductance, and chlorophyll content were evaluated at 180 and 300 days. Significant differences among treatments indicated variation in seedling vigor, likely associated with genetic or environmental differences among matrices. In Experiment II (Sun and Shade), seedlings were subjected to full sunlight or shading for 30 days. Only chlorophyll content differed significantly between treatments, although all seedlings exhibited similar growth patterns and high survival rates, highlighting the species’ marked physiological plasticity in response to light availability. Overall, the results demonstrate that E. involucrata possesses high plasticity and strong natural regeneration capacity, reinforcing its suitability for ecological restoration programs in degraded cerrado sensu stricto areas.