Temporal Rhythms of Dry Tropical Forest Regeneration under Exploration of Granite-Gnaisse Mining in a Semi-Arid Area

Abstract

This research aims to identify and analyze the level of regeneration of Caatinga vegetation in different stages, under the impact of granite-gneiss mining in a semi-arid region in Northeast Brazil. To carry out the floristic and phytosociological survey, four areas of vegetation cover were selected in different stages of regeneration: 20 years (closed bush shrubland); 15 years (open bush shrub); 10 years (sub-shrub Caatinga); 50 years (reference area with shrubby Caatinga). The species records of the four sampled areas were compared using the Jaccard and Sorensen similarity index. For the phytosociological analysis, the parameters of Basal Area, Absolute and Relative Density, Absolute and Relative Dominance and Coverage Value of the species were calculated. The floristic survey registered 5,494 individuals belonging to 14 families and 34 species. It was found that Euphorbiaceae and Fabaceae were the families that contributed with the largest number of species in the tree and shrub components. The species in the areas where there was exploitation 20 and 15 years ago showed a regeneration process close to that registered in the preservation area for 50 years. However, with respect to wealth, the 20-year area showed the greatest abundance. From the results it was possible to know the process of regeneration of the pioneer and secondary successional species in the Caatinga, contributing to the preservation of the species and the recovery of degraded areas in the semi-arid region of Paraíba. Contribution/Originality: The exploitation of granites and gneisses has a high economic impact in the state of Paraiba. There are extensive areas under environmental impact and biological loss due to the removal of vegetation. We characterize the rate of regeneration of Caatinga vegetation with a history of exploitation of these rocks.