Regenerative potential of the soil seed bank along an elevation gradient of rupestrian grassland in southeastern Brazil

Abstract

The objective of this study was to determine the species richness and abundance of the seed bank and the influence of soil attributes along an elevation gradient (800–1400 m a.s.l.). We examined the floristic similarity among areas and determined the regional diversity along this gradient in Serra do Cipó (Minas Gerais, Brazil). A total of 1975 individuals from 149 species were germinated. Richness and abundance were not linearly related to elevation, and exhibited a threshold at 1200 m. The low degree of similarity among the areas reflects environmental heterogeneity, resulting from a rich mosaic of habitats, distinguished by the substrate configuration, continuity of vegetation, floristic composition, and proportion of exposed rock. The diversity between plots of different areas (β2) contributed to regional diversity, and species turnover was the most important factor. The physical variables and base saturation, which had high spatial heterogeneity, may be the most important factors with which to determine species turnover and β diversity. The studied seed bank is strongly influenced by edaphic variables, with a gradient of increasing acidity and proportion of fine sand, and decreasing proportion of clay and organic matter, with elevation. In addition, species richness was influenced by cation exchange capacity, organic matter, and clay; and abundance was influenced by cation exchange capacity, H + Al, organic matter, and base saturation.