Regeneração natural em fragmento florestal do refúgio de vida silvestre mata de miritiba, Abreu e Lima, Pernambuco

Abstract

The Mata de Miritiba is an Integral Protection Unit, as a Wildlife Refuge was acquired by the brazilian army in the mid-1940s, when the property wascovered by sugarcanecrop, after abandoned, and recovered byforest spontaneous regeneration. The objective of this research was to evaluate if there was influence of the dam in the establishment and distribution of regenerating vegetation in the Miritiba Forest. In order to carry out the work, were released 15 transects of 100 m in transverse direction at the margin of the dam. In each transect, were released four parcels with dimensions of 5.0 x 5.0 m (25.0 m ²), at different distances from the margin of the dam, being considered as: Environment I, closed to the dam (0.0 to 10.0 m); Environment II, plots between 30 and 40 m; Environment III, between 60 to 70 m; and Environment IV, between 90 to 100 m from the dam, totaling 60 plots and 1,500 m² of sampling area.Were quantified and listed all individuals with height (H) ≥ 1.0 m and circumference at breast height (CBH) < 15.0 cm, identified in the field, when possible, being collected botanical material for confirmation in the Herbário Sérgio Tavares (HST). After identification, was prepared a floristic list with successional dispersal syndrome and spatial distribution of the species, and calculated Shannon diversity (H') and the Pielou evenness (J). The floristic similarity between the environments was held by the UPGMA ordering method. To verify the presence of indicator species in each Environment, was released an ISA. Phytosociological parameters of natural regeneration, using Microsoft EXCEL software tool for Windows™, 2007 and Mata Nativa. For analysis of the vertical structure of the regenerating vegetation, were considered three height classes, where: Class 1: 1.0 ≤ H ≤ 2.0 m; Class 2: 2.0 < H ≤ 3.0 m; Class 3: H > 3.0 m and CAP ≤ 15.0 cm.To the presence of indicator species of each environment, an ISA was performed. Floristic similarity was performed using the UPGMA ordering method. And the phytosociological parameters of Natural Regeneration, using as software tool Microsoft EXCEL for Windows ™ 2007 and Mata Nativa software. Physical and chemical analyzes of the soil were carried out at the Fertilization Laboratories of Soil Physics of the Instituto Agronômico de Pernambuco (IPA). Calculation of average, standard deviation and coefficient of variance (%) of the soil components was carried out. Principal Component Analysis (PCA) was carried out to evaluate which chemical and physical variables of the soil characterized the plots with the aid of the FitoPac program. A total of 1,411 regenerating individuals belonging to 67 species were sampled in 28 botanical families, five of which were indeterminate.In relation to the number of individuals, the species Protium heptaphyllum,Eschweilera ovata and Hyrtela racemosastood out. These species also stand out in dominance and frequency. The species Protium heptaphyllum also presented high rates of natural regeneration in the three height classes studied mainly in environments I and II, closer to the dam; and Eschweilera ovata stood out in environments III and IV. According to the distribution of the species, 83% show an aggregate and uniform spatial distribution. For the dispersion syndrome, Zoocoric was predominant, with a percentage of 84%. For the ecological groups, 51% were classified as late secondary (St). There was dissimilarity between the environments because it did not differentiate in the formation of distinct groups in the composition of the natural regeneration. The Analysis of Indicating Species (ISA) and the Monte Carlo test presented values of percentages ≤ 0,05, indicating four species for the environments, being three for Environment IV: Eschweilera ovata, Parkia pendula, Thyrsodium spruceanum; and one species for Environment I, Miconia prasina.