John Dennis

US National Park Service, Wildlife and Vegetation Division

Congress established the National Park Service (NPS) in 1916 to manage parks to preserve natural and cultural resources for the benefit and enjoyment of the people of the United States. Today, the NPS recognizes that parks are parts of larger regional environments.

National Park Service management policies of 1988, key goals:

• maintain natural environments to evolve with minimal disturbance by humans
• manage natural resources with concern for ecological processes as well as individual species
• in managing parks, maintain all components of naturally evolving systems, including ecosystem integrity
• recognize that exotic (non-native) species are a form of disturbance by humans

Invasions: the good, the bad, and the ugly:

• the good: natural range extensions of native species that occurs naturally -"white hat" species invasion - change is recognized as a natural part of the functioning of natural systems - use locally native species gene pools for restoration.
• the bad: "black hat" exotic invasion that occurs as a result of human action and where introduced species are not natural components of the system - management policy is a triage approach, with high priority given to exotic species that have substantial impact and can be controlled successfully; little attention to those we can't control or which have little impact.
• the ugly: "gray hat" species native to bioregion but not native to park itself; interference with natural processes is allowed to restore past invasion damage - try to attain approximation of natural system if actual restoration is not possible. And some of these can be used to control exotic species.

Questions that arise when trying to manage parks from this policy bible:

• Is the policy scientifically valid and can it realistically be achieved?
• What are "natural processes"?
• What scales are important?
• What elements of biodiversity are important?
• Can we recognize and help the good species?
• Can we attack the bad?
• Should we pack species into the park?
• Should we help species across fragmentation barriers?
• Should we attempt to anticipate global climate change and relocate species, especially long-lived ones such as certain trees?
• Is it OK to insert more exotics to control other exotics?