Abstract

Australian Acacia species ('wattles') have been intentionally introduced into South America mainly for forestry, dune stabilization and as ornamental plants. A small number of these species have become invasive, generating multiple impacts that contribute mainly to the loss of biodiversity and changes in the environmental conditions of ecosystems. This chapter reviews the introduction history, distribution patterns and impacts of Australian Acacia species in South America, focusing mainly on Brazil and Chile. We also provide guidelines to improve management and control of invasive wattles to reduce their impacts on South American ecosystems. During the last century, about 25 Acacia species have been reported in Brazil and Chile, where they mainly invade ecosystems considered biodiversity hotspots and generate impacts on biodiversity as well as on environmental conditions. The impact of wattle invasion in South America has been little studied, but recent papers show that Acacia species can affect biodiversity and ecosystem functioning. In Brazil, reported impacts include the reduction of water resources, losses of farmland and increased labour costs to prepare crop felds. In Chile, a negative relationship between the presence of A. dealbata and native plant richness has been reported and there are clear indications of a positive feedback between invasions and fre intensifcation in south-central Chile. In contrast to Brazil and Chile, knowledge of the history, distribution patterns and impacts of wattles in other South American countries is limited. Considering that Acacia species are economically important in South America, new populations or even newly introduced wattle species will likely invade, increasing impacts on ecosystems and biodiversity. Therefore, concrete actions to reduce the establishment, advance and impact of wattle species are needed. Collaboration across countries in South America is critical to develop the best tools for local stakeholders. © CAB International 2023. All rights reserved.