Defining Indigenous Species: An Introduction

It may seem curious to begin a book on management of plant invasions with a chapter on defining indigenous (IN) species. The first objective, however, in making a decision to manage a potentially problematic species invasion is to first determine whether a species is a natural component of, or is indigenous to, the community in question. It is important that specific criteria for determining species membership (specific status) within a plant community are defined. Using specific status as one among many tools, scientists and land managers can begin to assess invading species and develop management strategies. There is an abundance of terms (often differently defined and applied by various researchers, land managers, and regulatory agencies) describing specific status (native or indigenous versus exotic, alien, or nonindigenous [NM, mode of entry (locally persisting, waif species, escaped, adventive, naturalized, or introduced), and population trend (noninvasive versus weedy or invasive) in local, natural vegetation. As a rule, ecological terminology is messy; discrete ecological categories rarely exist. Ecologists continue to debate the precise meanings of fundamental terms such asecosystemcommunityand evenspecies.The need for unambiguous definitions and categorizations may seem obvious, but the actual categorization of species is often quite difficult. Terms such asindigenousandnonindigenousthat appear to clear and concise are often not.