Exotic forage grasses in the Brazilian semi-arid region: Forage mass, competitiveness, and botanical similarities of non-native pastures

Abstract

This study evaluated the competitiveness and productivity of four non-native grass species from Africa introduced in the Brazilian semi-arid region. The experiment had a randomized block design with four replications. The grasses evaluated were Cenchrus ciliaris L., Digitaria pentzii Stent, Urochloa mosambicensis Hackel Dandy, and Megathyrsus maximus (Jacq.) B. K. Simon & S. W. L. Jacobs. Megathyrsus maximus and Urochloa mosambicensis showed the best combination of greater forage mass per harvesting (1818 and 1141 kg dry matter (DM) ha−1 per 35-day, respectively) and lesser herbage accumulation of weeds (453 and 156 kg DM ha−1 per 35-day, respectively). Despite the differences in suppressing the weed mass between different non-native grass species, all grasses showed a considerable level of similarity between their floristic composition (family-level 70%, species-level 60%). All pastures were characterized by a higher number of herb weeds than shrubs and trees, however, there was more mass accumulation from shrubs. The tallest grass in the study (Megathyrsus maximus), and the one with the best dispersing capacity (Urochloa mosambicensis), showed advantages in outcompeting the native weeds and accumulate forage mass. The intense incidence of broad-leaf shrub species must be taken as a signal of the initial stages of pasture degradation and ecological succession.