Chemical control of the invasive exotic Acacia melanoxylon R. Br. and plant succession in the Pampa Biome (Argentina)

Acacia melanoxylon is considered an invasive tree species in Argentina, particularly within the Tandilia Hill System, where it has rapidly expanded, affecting native grassland ecosystems. The aim of this study was to evaluate the chemical control of this invasive species within a Private Natural Reserve located in the Tandilia Hill System and to assess the natural succession of vegetation after tree removal. To achieve this, an experiment was conducted using a Randomized Complete Block Design with four replications and four treatments. In three treatments, different herbicides were applied, while one treatment served as a control. From November 2016 to October 2018, vegetation species were recorded. The variables analyzed included green foliar coverage of the acacias , green foliar coverage of the Poaceae assemblage, and vascular species richness. Significant differences in green foliar coverage of acacias were detected between treatments on all sampling dates. An increase in the average green foliar coverage of the Poaceae assemblage was observed in the Picloram + Triclopyr treatment. No significant differences in species richness were detected between treatments at the final sampling date. This study demonstrated the effectiveness of the chemical treatments in controlling young A. melanoxylon trees. Furthermore, after a considerable time had passed since the application of the treatments, the Poaceae group and the percentage of native species were not negatively affected. This suggests that chemical control can not only be useful for managing this invasive tree species but can also contribute to the recovery of native ecosystems in the Tandilia Hill System.