12-4 Extinction Threats From Non-Native Species

What Is the Role of Deliberately Introduced Species? Good and Bad News

We depend heavily on non-native organisms for ecosystem services, food, shelter, medicine, and aesthetic enjoyment. The problem is that some introduced species have no natural predators, competitors, parasites, or pathogens to help control their numbers in their new habitats. Such species can reduce or wipe out populations of many native species and trigger ecological disruptions.

After habitat loss and degradation, the deliberate or accidental introduction of non-native species into ecosystems is the biggest cause of animal and plant extinctions. Non-native species put added pressure on endangered and threatened species by changing ecosystems and by competing with native species that may be already struggling to survive.

Case Study: A Plant Introduction with Unintended Consequences

In the 1930s, the kudzu vine was imported from Japan and planted in the southeastern United States to help control soil erosion. It does control erosion. But it is so prolific and difficult to kill that it engulfs hillsides, gardens, trees, abandoned houses and cars, stream banks, patches of forest, and anything else in its path.

Although kudzu can engulf and kill trees, it could eventually help save trees from loggers. Research indicates that kudzu may be used as a source of tree-free paper.

Solutions: How Can We Reduce Threats from Non-Native Species? Prevention Pays

Once a non-native species gets established in an ecosystem, its wholesale removal is almost impossible. Thus the best way to limit the harmful impacts of non-native species is to prevent them from being introduced and becoming established.

There are several ways to do this:

  1. Identify major characteristics that allow species to become successful invaders and the types of ecosystems that are vulnerable to invaders.

  2. Inspect imported goods that are likely to contain invader species.

  3. Identify major harmful invader species and pass international laws banning their transfer from one country to another, as is now done for endangered species.