Abstract
Rather than focusing on developing a single metric, a hypothesis-led approach to plant invasion impacts is needed - one that not only requires predictions based on the alien species' traits and recipient ecosystems' characteristics but also targets specific ecosystem stocks (eg soil C content) and the flow of materials between them (eg C sequestration rate). Instead of concentrating on many uncorrelated variables, this approach would entail focusing on targeted ecosystem metrics that are causally related (and hence not independent) to identify the consequences for ecosystem services and to better inform management.