Abstract
Invasion of non-native species causes detrimental impacts to biodiversity, ecosystem function, and human economies. To reverse these impacts, invasive species are often removed by trapping, shooting, poisoning, and other such methods. Growing evidence suggests that reducing invasive species can lead to successful ecosystem recovery. However, degraded ecosystems sometimes fail to recover, and reduction of invasive species sometimes result in even more harmful impacts. These unintended phenomena are increasingly recognized; however, few attempts have been made to integrate scattered information on solutions. In this review, I explore several possible situations that can cause unintended consequences, including environmental dependency, nonlinearity, hysteresis, and interactions among invasives, and relate these to processes such as switching, Allee effects, synergistic relations in both invasions and habitat modifications, mesopredator release, and so on. Additionally, I list management actions associated with each process, such as assessment of ecosystem recovery, habitat management, and management of other species. Practices mitigating unintended consequences using these actions are increasingly reported. Compiling the results of these trials would contribute not only to solving local problems, but also to guiding and facilitating further case studies.
