This study evaluated the possible effects of the use of herbicide and introduction of cool season species on the dynamics of natural grassland vegetation. The treatments were: natural grassland with annual mowing (CN); natural grassland improved with introduction of cool season species and annual fertilization (CNI); same as the previous but with glyphosate application (G1); same as the previous with three glyphosate applications (G3); same as G3 but with double annual fertilizing (GA3). The sod seeding of white clover, birdsfoot trefoil and annual ryegrass was preceded by application of the herbicide glyphosate. The grazing system was continuous, with variable stocking rates. The observed botanical composition was different (p < 0.06) between treatments that did not receive glyphosate application and those with application. The botanical composition of the treatments did not present variation (p = 0.57) among periods. The use of glyphosate allows an efficient establishment of the introduced species. However, the use of this practice is not recommended due to its effects on modifying the floristic composition of the natural grassland.
annual ryegrass; birdsfoot trefoil; glyphosate; white clover