Grassland vegetation of sandy patches of Rio Grande do Sul under grazing and exclosure

Abstract

The objective of this study was to characterize the effects of two grazing management on the natural vegetation, in the edge of sandy patches of Southwest of Rio Grande do Sul State, Brazil. Forty-one community areas of 4.5x9 m, were evaluated: 30 under grazing, and 11 under grazing exclusion. The vegetation composition in each community area was described by visually estimated cover-abundances of vascular plant species and bare-ground. Fifty-three 53 different taxa were identified from 43 genera and 16 families. Axonopus pressus, Elionurus sp., Schizachyrium microstachyum, Bulbostylis sp., Senecio sp., Baccharis coridifolia, Psidium sp., Cardionema ramosissima and Borreria verticillata were present in more than 50% of the communities. Andropogon lateralis was restricted to communities in Alegrete near to the Ibicuí River. Exclosures increase vegetation coverage and diversity, when compared to grazed ones. Natural vegetation under grazing is more susceptible to sandy patch process. Sandy patches under grazing have higher bareground and Elionurus sp., Axonopus pressus and Cardionema ramosissima