Revealing floristic and structural variation in regenerating areas in the Cerrado-Caatinga transition: an analysis across seres

Abstract

In the savanna-seasonally dry tropical forest ecotone in Northeastern Brazil, we studied variations in flora and structure within old growth and two sites in secondary succession (10 and 25 years). We sampled 2,127 trees and shrubs with a diameter at ground level of 3 cm or more, excluding cacti, palm trees, and vines. Old growth contained 478 plants from 29 species, the 25-year site had 819 plants from 27 species, and the 10-year site had 829 plants from 25 species, totaling 38 species across the sites. Regarding the regenerating stratum, we found 2,776 individuals, with the largest and smallest number of individuals for 10 and 25 years regeneration, respectively. Rarefaction and Jacknife richness showed greater tree richness in old growth, whereas 10 and 25 years regeneration presented similar richness estimates; furthermore, the highest richness in the regenerating stratum was observed in 10 years and the lowest in old growth. Our results reveal that changes in composition are caused by species replacement, demonstrating that even in areas deforested for traditional agriculture, turnover causes significant changes in composition and results in the requirement of a long time for reestablishment, similar to the old growth.