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.

本研究评估了从非洲引入巴西半干旱地区的四种非本地草种的竞争力和生产力。实验采用随机区组设计，重复四次。评估的草是Cenchrus ciliaris L.、Digitaria pentzii Stent、Urochloa mosambicensis Hackel Dandy 和Megathyrsus maximus (Jacq.) BK Simon & SWL Jacobs。Megathyrsus maximus和Urochloa mosambicensis显示出每次收获的较大牧草质量（分别为 1818 和 1141 kg 干物质 (DM) ha ^-1每 35 天）和较少草本杂草积累（453 和 156 kg DM ha ^{-1）的最佳组合}分别为每 35 天）。尽管不同非本地草种之间在抑制杂草质量方面存在差异，但所有草在植物区系组成之间都表现出相当程度的相似性（科水平 70%，物种水平 60%）。所有牧场的特点是草本杂草的数量多于灌木和乔木，然而，灌木的大量积累更多。研究中最高的草（Megathyrsus maximus）和传播能力最好的草（Urochloa mosambicensis）在竞争本地杂草和积累牧草质量方面表现出优势。必须将阔叶灌木物种的密集发生视为牧场退化和生态演替初始阶段的信号。