Biological invasions - How are they affecting us, and what can we do aboutthem?

Nonindigenous species affect native ecosystems. communities. and population s in myriad ways, from plants (and a few annuals) that overgrow entire comm unities. to plants and animals that hybridize individual native species to a sort of genetic extinction. Further, nonindigenous species sometimes inte ract to worsen each other's impact. These impacts are commonly seen in nati onal parks throughout the United States. The key policy change required to alleviate this threat is it shift from blacklists of prohibited species and it presumption of harmlessness to combinations of white and blacklists and a presumption that any species may be damaging. This new guiding philosoph y must be inculcated at international and national levels. which will not b e easy during a period when free trade is seen as an unmitigated blessing. Within the United States. enhanced cooperation and coordination will be req uired among all parties (i.e., federal, state, kind local agencies as well as private entities) charged with managing invasions. Internationally, the key forum is the World Trade Organization. Various management tools availab le to combat nonindigenous species have produced some striking successes, b ut new research could improve their effectiveness and reliability. There is a particular need for research on ecosystem management to control introduc ed species. In the face of the increasingly publicized onslaught of invader s, there is a widespread tendency to view increased biotic homogenization a s inevitable. However, advances in both policy and technology, could greatl y slow this process and perhaps (in concert with restoration measures) even reverse it. The necessary pressure and resources to effect these changes m ust come from an increasingly alarmed and vocal public.