Short-term effectiveness of Ulex europaeus control measures in Uruguay

Abstract

Gorse (Ulex europaeus L.) is a leguminous shrub native to western Europe, voluntarily introduced into Uruguay for ornamental purposes. It is considered among the 100 most problematic invasive species in the world. In Uruguay, it seriously affects both livestock and forestry systems. We evaluated different weed management techniques on a cattle farm invaded by U. europaeus, in the region of Lavalleja. In spring 2020, three treatments were applied— cutting only (C); cutting and grazing (CG); and cutting, applying herbicide, and grazing (CHG)—to 18 plots ranging from 25 m2 to 50 m2. Following treatment, U. europaeus regrowth and the height and the perimeter of five plants per plot, as well as seedling recruitment, were assessed over 16 mo. The livestock were cattle (Bos sp.) and sheep (Ovis sp.). The CHG treatment was the most effective in inhibiting the regrowth of U. europaeus, while grazed plants grew less in height compared with those excluded from grazing (CG = 62.3 cm ± 1.9, C = 84.8 cm ± 2.0, P < 0.05). However, by the end of the study, seedling recruitment was lower in the C treatment (C = 0.3 ± 0.3, CG = 3.1 ± 1.8, CHG = 8.6 ± 4.6 seedlings m−2, P< 0.05), where increased height of herbaceous vegetation may have reduced the success of the emergence and establishment of regenerants. These results encourage further long-term study of this invasive species’ response, as well as an evaluation of the potential impacts of these control measures on non-target species.