A Comparison of Different Views Concerning Invasive Exotic Species in Ecosystems

Conventional Thinking Alternative Hypothesis

Ecosystems infected with exotics are imbalanced systems that must be restored.

Our knowledge of exotics is sufficient to develop management strategies and value judgments on them.

Exotics are problems that must be exterminated.

Exotics should not be used in restoration projects; only native species should be used.

Ecosystems infected with exotics are less valuable because of their ability to outcompete or harvest to extinction native species.

All exotics should be controlled or kept out of natural systems to reduce their impacts.

Exotic-free ecosystems are attainable.

Ecosystems infected with exotics are examples of a new class of ecosystems heavily influenced by humans and have value of their own.

Almost all research on exotics has been at the population scale, with little emphasis on ecosystem relations. More research is needed on ecosystems with high amounts of exoticism (as opposed to endemism).

Exotic-dominated ecosystems may reveal some aspects of ecology that we have not seen previously; they are a scientific tool for doing ecological theory.

Exotics sometime grow faster or have special qualities that may speed up restoration. The key may be to managing exotics. This may be the most effective way of restoring ecosystems.

Exotics may improve certain overall ecosystem parameters such as biomass, production, decomposition, stability, and even diversity.

The best way to manage exotics may be to add more exotics, so that more control networks (food webs) will arise.

There is no way to keep exotics out or to remove them once they have invaded. Exotics may be inevitable. Humans are exotics.

can cause to natural ecosystems (Bates and Hentges, 1976; Ewel et al., 1999). This chapter examines the positive and negative contributions exotics make to biodiversity and outlines the new form of organization they represent. Exotic species provide opportunities to learn about basic ecological structure and function, if viewed objectively, and their success is a challenge to existing ecological knowledge. Finally, ideas of control strategies are reviewed. These strategies vary in their effectiveness and may be better described as management rather than engineering. As a group, exotics are forms of biodiversity that have escaped control by factors that would have regulated their populations. Thus, concepts of control in ecology and engineering are discussed for perspective.

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