WHAT ARE ALIEN SPECIES HARMFUL TO NORTH AMERICAN FOREST?
2. Alien species are, with respect to a particular ecosystem, any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that ecosystem.2 When they cause changes in ecosystems, displacing native organisms by predation or parasitism, by competition for space and nutrients or food, or by alteration of habitats, alien species are considered to be invasive. When their impacts are beyond acceptable levels, resulting in environmental damage and economic and social losses, alien species become known as pests. In a more narrow classification, the 1997 revised text of the International Plant Protection Convention (IPPC) defines a quarantine pest as “a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled.” Discussions continue in several fora, including the International Convention on Biological Diversity (CB
