The threat of invasive alien species to biological diversity: Setting a future course

Over the past decade, mounting evidence has shown the pervasive and escalating harmful impacts of invasive alien species on native species and ecosystems. Thousands of non-native species are established in the United States and many more worldwide. Few areas appear immune to invasions, some of which unfold over decades to centuries as species' ranges slowly expand across the landscape. A plethora of ecological effects have been attributed to invasive species, and other global change processes and widespread habitat destruction will likely multiply these effects. Many conservationists now consider invasive species among the top threats to biological diversity and are grappling with identifying pragmatic, effective solutions. They know that the future will involve mixed assemblages of native and non-native species and have important questions about which invasive species to tackle and which ones to ignore, and even whether to deliberately introduce certain species for restoration. Addressing these issues will push hard against the limits of today's ecological knowledge and our ability to predict the long-term ecological consequences of such decisions. Better envisioning the conservation goals, though, could help to guide the science.