Landscape Ecology BT - Ecological Systems: Selected Entries from the Encyclopedia of Sustainability Science and Technology

Abstract

Biological invasion is the process by which a species is introduced, deliberately or inadvertently, into a new geographic region where it proliferates and persists. Outside their natural range (in which they evolved) such species are described as nonnative (or nonindigenous, exotic, alien). For a variety of reasons, the vast majority of introduced nonnative organisms fail to persist. Many of those that do establish self-sustaining populations do not spread very far or very fast beyond their point of introduction, and they often do not have conspicuous impacts on their environment. However, a small proportion (but a large and growing number) of nonnative species becomes invasive – that is, they may spread aggressively and/or have strong environmental effects. Invasive species are a global problem that threatens native biodiversity, the normal functioning of ecosystems, natural resources, regional economies, and human health. As such, they pose a major concern for conservation and management, and are the focus of a highly productive multidisciplinary field called invasion ecology.