A DEFENSE OF INVASIVE SPECIES.

A DEFENSE OF INVASIVE SPECIES. I have conflicting feelings about invasive species. Matt Ridley argues that they are sometimes good things: “Some ecosystems are enriched and made more productive by invasive species.” He supports this with examples of invasive species that provide improved “ecosystem services” such as creation of soil and the prevention of erosion. He gives the example of gray squirrels in the United Kingdom, who are displacing the red squirrels that have been there since the ice age. He says: “ecologically,…the gray is better at filling the squirrel niche in [the UK] broadleaf woodland’ because red squirrels are a “pine-adapted species”. Of course, there is a weakness in his argument. A successful invasive species will be successful because it is better adapted to an environment. The question of whether invasive species are bad in themselves is a different one—and, I think, an aesthetic question.