Does Buffelgrass Have a Long Permanence in an Established Pasture? An Analysis of the Population Dynamics of This Exotic Grass in Central Sonora, Mexico

The introduction of exotic forage species to new environments for livestock purposes is a common practice to increase productivity. Unfortunately, the population dynamics of introduced species as well as that of native species that persist in grasslands has been poorly studied. In Sonora, the introduction of exotic buffelgrass pasture has caused substantial modifications in the structure of desert scrublands. In this study, an evaluation of the population dynamics of buffelgrass pasture in two grasslands with different times (10 and 50 years) was carried out using classification by size category according to the total number of stems per plant. For each size category of stems, the probabilities of permanence, transition, and regression, and for estimating seed establishment and fecundity were evaluated. The results obtained indicate that in both grasslands, the population growth values (λ) were slightly greater than 1 (λ > 1), which indicates that the populations are stable. The results of this study suggest that the permanence of individual buffelgrass plants in established grasslands is the determining factor in λ. Likewise, our results suggest that in both grasslands, pasture management plays an important role in the permanence or deterioration of buffelgrass pastures.