Adventive

Adventive is an ecological term used to describe a species or organism that is not native to a region but occurs there, typically as a result of human activity or, less commonly, rare natural displacement. In botany, zoology, and ecology, an adventive taxon is part of the local biota only because it has been introduced from outside its native range.

A key distinction is between adventive and naturalized. Adventive populations may be casual, temporary, or irregular and do not necessarily establish self-sustaining populations. Naturalized species, by contrast, have established self-perpetuating populations in the wild without ongoing human assistance. Related but different is the category of invasive species; many adventives may become invasive if they spread and cause ecological or economic harm, but not all adventives become invasive.

The term is used across disciplines. In botany, adventive plants can arrive through cultivation, garden escapes, ballast water, or seed contamination and may persist in disturbed habitats or fail to establish. In zoology, adventive species are non-native but may not have established populations; if they do, they may be labeled naturalized. In microbiology and plant pathology, adventitious (adventive) organisms or propagules describe pathogens or microbes accidentally introduced into new hosts, environments, or cultures.

Status assessment relies on regional flora and fauna checklists, which distinguish native, adventive, naturalized, and invasive taxa. Understanding adventive species helps researchers track introductions, assess ecological risks, and inform management decisions without assuming a non-native status implies harm.