Viewing invasive species removal in a whole-ecosystem context

Erika S. Zavaleta, Richard J. Hobbs and Harold A. Mooney

This article makes clear the complications involved in invasive species removal. Namely that the removal of one species can have unforeseen consequences on other invaders, and thus on the system as a whole. If you take out an invasive herbivore, maybe thistle goes crazy; or if you take out an invasive predator (like cats), maybe an invasive herbivore (like rabbits) goes crazy; and there are many other examples used to show the inherent difficulties of invasive removal when complex relationships are involved. Each removal from the food web will have an impact both above and below that species, and when an ecosystem has been hit with multiple invaders, as is often the case, it becomes more and more necessary to take the implications of restoration decisions seriously. Within this context the authors argue for stricter and more careful management of ecosystem restoration. More time spent beforehand determining the likely impacts of removal, and more time spent afterward with careful monitoring of the system. This is an argument against knee-jerk invasive removal, and for holistic ecosystem-level awareness in restoration. Brings to mind a question: are there situations when a novel ecosystem with multiple invasives reaches a more stable state than what we could realistically hope to restore it to?

The logic of this article is hard to argue with, and the multiple brief case studies make it an interesting read. But if these ideas are common sense to you, and you’re already in agreement with the premise, it’s not a necessary read.