The 'WATTLES' invasion syndrome

The term 'invasion syndrome' refers to a combination of pathways, Alien species' traits and characteristics of the recipient ecosystem which collectively result in (invasions with) predictable dynamics and impacts, And that can be managed effectively using specifc policy and management actions. Grouping invasion events into invasion syndromes thus allows for useful generalizations and the identifcation of transferrable risk-assessment and management lessons across different contexts. In this chapter, We use information and insights from the different chapters of this book and argue that invasions of Australian Acacia species ('wattles') constitute a distinct invasion syndrome which we dub the 'Woody Australian Trees that Transform landscapes: Leguminous, Enemy-free, With persistent Seed banks (WATTLES)' invasion syndrome. The WATTLES invasion syndrome includes woody wattles that can form large long-lived seed banks and that are introduced with high propagule pressure together with their compatible rhizobia (or into areas with compatible rhizobia) into regions with suitable climates and that lack specialist natural enemies. When this happens, The introduced wattles establish invasive populations and modify the hydrological, Nutrient and fire cycles of the invaded ecosystems, Often leading to invasional meltdown and the displacement of native species. WATTLES should be prevented by carefully regulating or prohibiting deliberate introductions, And, Once established, Can be managed using classical biocontrol supplemented by physical and chemical methods as needed, Noting that expensive active restoration efforts might be required if the goal is to return the system to a pre-invasion state. The WATTLES invasion syndrome delimited in this chapter is potentially extendable to other woody legume invasion events, Such as those of Prosopis spp. and Robinia pseudoacacia.