Sometimes, introducing invasive plants and animals into a habitat is the equivalent of throwing a wrench into the cogs of a machine: In some cases, the machine continues to operate, but at a much-reduced efficiency.
In other cases, the machine shuts down completely. Last week was National Invasive Species Awareness Week. The purpose of this week is to bring attention to all non-native species that pose threats to our outdoor habitats.
Unfortunately for our habitats and native species that reside in them, there are a large number of non-native invaders and many of them can be harmful to our ecosystems.
Invasive species – which, in most cases are non-native exotic species – are nothing new. A variety of animals and plants have been introduced to North America in the 500-plus years that the continent has been explored, settled and developed.
Some were introduced on purpose, others by accident. These introduced species are collectively known as “exotic” species because they’re not indigenous to North America. The opposite of exotic is “native.” Native species are the plants and animals that were the original inhabitants of our landscape.
Some exotic plants, such as kudzu and fescue, are well-known to people, but there are many others. Some have become so common that we don’t realize they’re not from around here.
Take, for instance, the two most common types of crabgrass found in residential yards – hairy crabgrass (Digitaria sanguinalis) and smooth crabgrass (Digitaria ischaemum). Neither is native to North America; they were introduced here, probably in the 19th century.