Invasive Species and How They Harm the Environment

It's not as if the environment needed another destructive element in addition to encroaching development and pollution, but it has one anyway. There is really big threat that can and does wipe out native species in all kinds of ecosystems. It can come in a host of different types and can affect plants and animals equally. It's called invasive or exotic species.

What this means is that a species other than what originally inhabited an area has moved in, or it at least threatening to move in, thereby pushing out the native species. When this happens, the natural balance of the ecosystem is changed and therefore, the other species living in the area must adapt or die off. Nature is all about balance, so when something happens, whether naturally or artificially, adaptation is necessary. Most species can't adapt fast enough and die or move away. In a natural occurrence, such as a flood, earthquake or drought, nature will ultimately create a balance again after a while. But when this happens artificially, by invasive species, balance can't be achieved without help.

The majority of invasive species are opportunistic and very well adapted to move into a niche, taking over quickly, until they create an inhospitable environment for the native species. Many animals and insects have adapted to living on, in or near a particular species within their ecosystem, so when those native species are replaced, there is no longer the habitat there that they need. When the balance is gone, it doesn't just affect one species, but most or all of them. A keystone species is one that is at the center of the ecosystem, or the one that drives the ecosystem. If that keystone species is removed, all the others that in one way or the other depend on it will suffer.

Almost all invasive or exotic species were accidentally introduced, but some were introduced on purpose through thoughtlessness. Years ago, when not much thought was given to how an introduced species might affect the local ecosystem, landscapers or home owners would plant imported trees simply because they looked good or provided good shade. However, as these decorative trees thrived in their new environment, they spread their seeds into the lands outside of the residence or business. Some of these species, such as the tree tamarisk, began to inhabit areas along streams and creeks, leaving little room or water for the native willow trees. Tamarisk trees have deep root systems that seek out water. The tamarisk flourishes but they don't provide the needed habitat that birds and animals require. They drink up the water and lower the water table so that many native plants can't grow.

Other exotic species that are very problematic is the bull frog and the African clawed frog. These frogs prey upon the native frogs and their tadpoles, as well as native fish and invertebrates. There are conservation groups that attempt to remove the invasives and have had some luck, but it's a constant battle.