Composition and structure of natural regeneration in nine years after the extraction of Eucalyptus grandis Hill ex. Maiden in Itajaí Valley, SC

Abstract

Natural regeneration is considered one of the most promising techniques for restoration of degraded areas due to ecological, silvicultural and economic aspects. The present study aimed to evaluate the characteristics of natural regeneration at different ages of establishment, in permanent preservation areas, after Eucalyptus grandis stands extraction. A survey and floristic analysis of the regenerating vegetation was performed in areas with natural regeneration ages of five and a half, seven and nine years, along the banks of a watercourse. Fifty-six sample plots of 10m x 20m were implanted for the tree stratum survey and the same number of subunits for the regenerative stratum survey. Floristic analysis was performed by area and vegetation stratum, and the comparison between the three environments for richness, diversity, distribution of ecological groups and dispersion syndromes. The vegetation studied showed floristic composition changes along nine years. The number and density of pioneer species suffered decrease in both the arboreal and regenerative stratum, while shadow-tolerant clímax species had increase as the regeneration ages progress. Light demanding climax species were prevalent in all three environments, as was zoochoric dispersal syndrome. The diversity for the three areas analyzed, and for both strata, was increasing with the regeneration ages. Environments with seven and nine years of regeneration presented higher percentage of common species, besides density and distribution of more similar ecological groups in relation to environment with five and a half years of regeneration.

Keywords:
Natural regeneration; Successional dynamics; Dispersion syndromes