For example, at dinner last night we had 14 exotic species and just two native ones. The idea of harmful exotics is not new but attitudes on the subject have changed in the past 20 years. Humans have cut down 32 million acres of long leaf pine forest in North Carolina alone.
Biological pollution is a global issue.
They can do more and we can do things too. We can't stop all invasions but we can minimize them. Weed science, biology, and plant quarantine are three fields concerned with non-indigenous invasive species. The issue of species movement began with Pangea, the huge supercontinent that existed 250 million year ago when species could move around freely. Differing climates and soils, the physical separateness of the continents, and other factors maintained these distinct ecosystems.