Serras: refúgios da caatinga no cariri paraibano?

Abstract

The understanding of diversity patterns and processes involves some aspects such as environmental heterogeneity, conditions and existing resources and biotic interactions beyond human intervention. In recent decades, the altitudinal studies has aroused the attention of ecologists and are considered effective research tools, however, the historical use and geomorphological changes in each environment should be considered. The savanna is characterized by the diversity of faces, however, his characterization goes back to colonial periods and much of the vegetation cover is fragmented and in different successional stages. This study is structured into two chapters. The first focuses on the influence of altitude (altitude 1:400; altitude 2: 500 and altitude 3: 600 m a.s.l.) in the richness and plant community structure, Cariri of the Paraíba. The second chapter aims to test the hypothesis that the mountainous areas of the Massif of the Borborema have more species of shrub and tree component, as refuges of savanna setting. The study was conducted in the following areas of the mountain Cariri: Bodocongó, Arara, Inácio Pereira, Bonita and Fontainha beyond the areas of the Borborema plateau of the Massif: Farm Bodopitá, Caiçara, INSA, Poço de Pedra and Pocinho. We used two sampling methods: plot sampling and point-quadrant. We obtained the common name, diameter at ground level, height, habit and distance from the plant to the point. The phytosociological parameters of diversity and evenness indices were calculated from the Mata Nativa 3. In order to assess the patterns of wealth, we used the randomization test from the program EstimateS 8.2, with the construction of collector curves and nonparametric estimates. We recorded 2911 individuals belonging to 24 families and 70 species and 2208 individuals, 27 families and 71 species in the first and second study, respectively. The most representative families were Fabaceae, Euphorbiaceae, Cactaceae, and Apocynaceae. In the first approach of this study, we observed the increase of wealth component of shrubs and trees along the elevation gradient studied. Certain species were restricted to specific altitudes, being found in three altitude greater horizontal distribution of species. It was also observed that the influence of altitude is indirect, and human action is the main factor responsible for plant community structure in such areas. On the second section, it was observed that the mountainous areas have more species compared to the plateau areas. The data reveal a poorer surrounding matrix in relation to wealth, diversity and evenness, and species with high frequency such as Croton blanchetianus Baill. We conclude that human intervention in natural environments, not unlike in the semiarid region of Paraíba, has changed the patterns of diversity, leading to the impoverishment of restricted areas and a greater diversity of shrub and tree component in mountainous areas.