Evidence-based impact assessment for naturalized Acacia species
ID: 613 / 462
Proposed Symposium Title: Evidence-based impact assessment for naturalized Acacia species
Sabrina Kumschick1, Cally Jansen2
Affiliations: 1 Centre for Invasion Biology, Stellenbosch University, Stellenbosch, South Africa 2 3School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
Australian Acacia species (‘wattles’) have been transported across the globe, with devastating effects in some introduced ranges where they have become invasive. However, the impact of alien taxa can be measured and quantified in many ways, which makes synthesis of their overall impacts challenging. We assessed impacts of naturalized and invasive wattles on native biodiversity and human well-being, using two evidence-based and standardized approaches. Impact on native biodiversity was assessed using the Environmental Impact Classification for Alien Taxa (EICAT) scheme, the IUCN standard for assessing impacts of alien taxa. For impacts on human well-being, we used the Socio-Economic Impact Classification for Alien Taxa (SEICAT). For environmental impacts we found 169 records, with South Africa having the highest number of records (48), followed by Portugal (26) and Spain (20). Of the 87 Acacia species assessed, most taxa with impact records available were classified as having Major impacts. This means they lead to the local extinction of at least one native species in the introduced range. However, 70 species were classified as Data Deficient under EICAT. Only 19 records were available documenting impacts on human well-being associated with seven invasive wattles, and these generally denote only Minor impacts, with one exception of a Moderate impact where farmlands were abandoned due to A. mangium invasions. This shows a significant gap in data availability for socio-economic impacts of this group. Our study provides the most complete evidence base of impacts of arguably one of the most important groups of tree invaders globally. It highlights the need to use caution when introducing and using wattles outside their native ranges, and to apply best practice guidelines if use is inevitable.