Although it is now well-known that invasive species can have significant ecological effects, it is often assumed that if an invader has documented impacts in one location then the species will have equally negative (or positive) impacts elsewhere. At the same time, there is at least a conceptual recognition that the ecological impacts of invaders vary according to local environmental conditions and the ecological community with which they interact. The type and degree of differences in ecological impacts, however, is rarely empirically demonstrated. There is also growing recognition that we are largely ignorant of long-term ecological effects of invasive species, even to the extent of not fully understanding how persistent initially observed negative effects may be. We conducted a comprehensive systematic review of the invasion ecology literature published between 1999 and 2017 to identify the ‘known unknowns’ of invasive species impacts. We then consider these gaps in evidence in the context of proposed invasion impact hypotheses and frameworks
Results/Conclusions
The most commonly studied invasion impacts are at the community or population scales, and there has been very few published efforts to document how impacts integrate across ecological scales of measurement (individuals up to ecosystem). In addition, the invasion impact literature is heavily skewed toward evidence gathered over a very short time period and at single, small spatial scales. Most species appear in only one publication, and some ecosystems have received very little attention in terms of invasive species impacts. However, the species and ecosystems that have been received more research attention provide an evidence base for understanding the influence of spatial and temporal scale on invasion dynamics. This symposium highlights several of these examples, and explores how invasion ecologist can construct their research efforts to more effectively inform and generate invasion impact theory.