title: The natives are restless, but not often and mostly when disturbed.
abstract: The argument that the threat posed by introduced species is overblown is often buttressed by the observation that native species sometimes also become invasive. An examination of the literature on plant invasions in the United States shows that six times more nonnative species have been termed invasive than native species, and that a member of the naturalized nonnative pool is 40 times more likely than a native species to be perceived as invasive. In the great majority of instances in which a native plant species is seen as invasive, the invasion is associated with an anthropogenic disturbance, especially changed fire or hydrological regime, livestock grazing, and changes wrought by an introduced species. These results suggest that natives are significantly less likely than nonnatives to be problematic for local ecosystems.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996-1610, USA. dsimberloff@utk.edu
authors.forename: Daniel
authors.initials: D
authors.lastname: Simberloff
authors.forename: Lara
authors.initials: L
authors.lastname: Souza
authors.forename: Martín A
authors.initials: MA
authors.lastname: Nuñez
authors.forename: M Noelia
authors.initials: MN
authors.lastname: Barrios-Garcia
authors.forename: Windy
authors.initials: W
authors.lastname: Bunn
mesh_terms: D017753:Ecosystem; D058865:Introduced Species; D014481:United States