Vegetação lenhosa adulta e regenerante em uma cronossequência na mata atlântica de Pernambuco e sua relação com o solo

Abstract

Due to the reduction of forest areas, for agricultural or pastoral purposes, it has become it is more difficult to find remnants that characterize the plant formations of the Atlantic Forest in the state of Pernambuco. The objective of this work was to evaluate the richness and diversity of species between two fragments of the Semideciduous Seasonal Forest in the North of Pernambuco Forest Zone at different stages of conservation, correlating with the chemical and physical characteristics of the soil. For this, the study was developed in two fragments of a forest area belonging to the Olho d'Água Central Plant, located in Camutanga, in the North Forest Zone of Pernambuco. The first fragment, called Mature Area, is an area of 350 ha and a historic of use that refers to at least 100 years without direct interventions. The second fragment, called the Youth Area, has 68 ha and has been regenerating naturally for about 30 years. For the floristic survey of the tree community, 20 plots (25 m x 10 m) were systematically allocated in each area, constituting a sample area of 0.5 ha, sampling individuals with circumference at breast height (CBH) ≥ 15.0 cm, observing the total height. In order to evaluate the natural regeneration of the tree species, subplots of 25 m² (5.0 m x 5.0 m) were allocated to each plot, considering regenerants individuals presenting h ≥ 1.0 m and CBH < 15.0 cm. measured in the circumference at 30 cm and the total height, aiming to group them by height class. The collected material was properly herborized for identification purposes. Floristic diversity, dispersal pattern of diaspores and analysis of the horizontal structure were evaluated, as well as the classification of these individuals into ecological groups, using the software Mata Nativa Version 4. Soil samples were collected to determine the physical and chemical properties and the organic matter, and the Analysis of Canonical Correspondence was carried out in order to verify if the environmental variables related to the soil influenced the composition of species. As results, in the Mature Area 509 adult individuals were identified as belonging to 66 species; and 254 individuals in the regenerating arboreal component belonging to 36 species, with higher representativeness of the families: Fabaceae, Euphorbiaceae, Myrtaceae and Rubiaceae. In the Young Area, 286 adult individuals belonging to 36 species and 150 individuals in the regenerating arboreal component belonging to 24 species were identified, with the highest representation of families: Fabaceae, Myrtaceae, Erythroxylaceae, Rubiaceae and Sapindaceae. The Mature Area presented the greatest richness and diversity of species in both its adult and regenerating arboreal component, however, it was verified that there is similarity between the two areas. From the evaluation of the soil-vegetation relationship, it was observed that the successional stage and, in this specific study, the use history characterized by agricultural activities, exerted an important influence on the species composition in these fragments, observing a strong interaction of the physical and chemical features and the distribution of species in both areas, showing that the species of the Mature Area are more adaptable and less demanding, different from the species of the Young Area.