Natural regeneration after 13 years of revegetation with nitrogen-fixing trees in Valença, Rio de Janeiro state, Brazil

Abstract

This study aimed to evaluate the ecological succession under different proportions of nitrogen-fixing trees intercropped with non-nitrogen fixing trees species through the understory floristic survey. A randomized block design with four treatments and three replications was conducted for 13 years with 30, 50, 65, and 80% of nitrogen-fixing trees in the whole plants used per plot. Fixed subplots with 10 m x 10 m were installed at the experimental plots and evaluated all individuals with height ≥ 60 cm to carry out the floristic survey. The species were identified and classified according to growth habit, the successional class, and dispersion syndrome. The natural regeneration vertical structure was evaluated with the following indicators: absolute density, absolute frequency, and relative frequency, the horizontal structure with Shannon’s diversity index and Pielou’s equitability index. The survey founded 37 species that had not been planted initially. Only three of the 13 planted species were present in the seedling bank. It was identified a more significant presence of pioneer trees species with zoochoric dispersion in the four treatments understory, indicating that the species mixed allowed the activation of the natural succession process. Treatments with 50 and 65 % of nitrogen-fixing trees favoured the diversity of species.

Keywords:
Leguminous trees; Land reclamation; Semideciduous seasonal forest