Plant communities developed on alkaline soils of the Pampa Ondulada region in Argentina are already described from a floristic point of view. The goal of this paper is to analyze the effect of different managements on community structure. The following experimental plots were set in March 2001: (1) control; (2) chisel plough tillage and fertilization; (3) fertilization and sow of Festuca arundinacea, festuca and Lotus corniculatus, lotus; and (4) gliphosate aplication, fertilization and non-tillage with sow of the same species. Intermitent grazings were allowed. On April and November 2001 and 2002 vegetation was surveyed in randomly placed permanent plots using a cover-abundance scale. Plot x species matrixes were built and analyzed by multivariate methods. Diversity (H’), richness (S), and evenness (E) indexes were estimated and compared using non-parametric methods. All diversity indexes (S, E and H’) and overall grassland cover were high at the beginning of the experiment. On November 2001 and April 2002, H’ and S significantly differed among treatments, with highest values found on treatment (1) and lowest ones on treatment (4). S values increased during the second spring due to restoration of original grassland species. Although management practices improved forage quality of study grassland in the short time, plant community showed poor resilience after agricultural disturbances, including incorporation of exotic species.