Floristic diversity in areas of sandy soil grasslands in Southwestern Rio Grande do Sul, Brazil

Abstract

Extensive natural grasslands areas in southwestern Rio Grande do Sul occur on sandy soils, which are susceptible to the sandy patch process. This process leads to the formation of large sandy patches, which constitutes a large-scale environmental problem. In grassland areas undergoing sandy patch processes in Alegrete, Manoel Viana and São Francisco de Assis municipalities, we recorded the occurrence of 343 species, 195 genera and 52 botanical families, with two new records for Rio Grande do Sul State (Eragrostis articulata (Schrank) Nees and Eragrostis leucosticta Nees ex Döll) and one for Brazil (Croton lorentzii Müll. Arg. ex Griseb.). The families with higher specific richness were Asteraceae, Poaceae, Fabaceae, Euphorbiaceae, Cyperaceae, Rubiaceae and Myrtaceae. From the whole species set, 19 species show a restricted distribution area, seven of these are exclusive to Rio Grande do Sul’s grasslands and 16 are considered as extinction threatened.