Vegetation responses to roller chopping and buffelgrass seeding in Argentina

T-4464 Buffelgrass (Cenchrus ciliaris L.) is an introduced grass used extensively for restoring forage capacity of denuded shrublands in the and Chaco region in central western Argentina. Currently, the technique of roller chopping and simultaneous buffelgrass seeding is widespread, but information is lacking about its effects on forage production and other vegetation attributes at the regional scale. The purpose of our study was to compare grass yield; vegetation cover and density; and species richness, diversity, and evenness, between roller chopping and simultaneous buffelgrass seeding with nontreated native degraded shrublands. Eight sites, including matched pairs of treated and nontreated areas, were studied. Grass yield, total perennial grass cover, and total perennial grass density were higher (P < 0.05) on treated areas. Increase in grass yield on treated areas compared with nontreated areas was related to the increase in total perennial grass cover due to added buffelgrass cover (r(2) = 0.79). Shrub cover was lower (P < 0.05) on treated areas, but shrub density was not different between treatments (P > 0.05). Nonsignificant differences (P > 0.05) between treated and nontreated areas were detected in tree cover and density, species number, diversity index, and evenness. The results of this study indicate that, in the short term, roller chopping and simultaneous buffelgrass seeding produces rapid increases in grass cover and grass yield, and a drastic reduction in shrub cover without affecting species diversity on degraded shrublands of the and Chaco region of Argentina.