Invasive Species Are an Emerging Causal Factor

Abstract

Each ecoregion has a group of species that naturally occur in wetlands. Invasive species introduced from other ecoregions can have strong negative impacts. Whenever possible, introduction of such species should be avoided. Five examples illustrate the broad array of negative effects produced by invasive species. Burmese pythons have invaded the Everglades and have reduced the populations of native mammals. The Emerald Ash Borer is killing ash trees, which are a dominant tree in swamps in eastern North America. Nutria is changing biomass in wetlands of North America and Europe. European Frog-bit is invading open water areas in North American wetlands. Giant cane is invading floodplains in semi-arid areas, excluding native species, and creating a fire-dependent vegetation type. There are three important lessons for management: (1) prevent invasive species from being introduced, (2) monitor wetlands regularly to detect new invasives, and (3) eradicate invasive species as soon as possible after detection, before populations grow so large that they cannot be controlled.