What is An Invasive Species?

By Joyce Chepkemoi on June 13 2018 in Society

Relict trillium competing with invasive species nepal grass.
Relict trillium competing with invasive species nepal grass.

An invasive species is plant, animal, fungi species that is introduced (non-native) to an ecosystem and spreads fast causing damage to animals, plants, and in turn the entire environment. These species are not native to a given place but are introduced unintentionally or knowingly. These species are also known as, “alien, introduced or non-native” species. Invasive species are known to cause economic, ecological, and environmental damage by shifting the natural bionetwork balance. It is imperative to note that not all non-native species are invasive and it is hard to classify an organism as invasive.


For a flora or fauna specie to be deemed invasive, its reproduction process must overcome some topographical barriers such as mountains and oceans. Invasive species also overcome environmental barriers of germination such as moisture availability, soil pH level, nutrient availability among other things. These alien species have a tendency of forming a self-sustaining population and do not need re-introduction in the same area. Their capability to endure in minor potions and spread fast is adequate. They can alter growth form to suit different environmental conditions. Their destructive nature overshadows its benefits.


Different species can have different negative impacts. These can range from diseases, poisoning, migration and even death. This leads to increased spending on medical care, decreased productivity among other negative incidences. An example of an invasive species is the West Nile virus which caused sickness and death of people and horses in the US. The Chinese Sumac Tree sap causes inflammation of the heart muscle after a minimal skin contact. Invasive species have caused death and migration of wild animals from their natural habitat and decreased the carrying capacity of the areas. These species have been known for deforestation and soil destabilization. To fight them, authorities use a lot of resources that would have been used in other productive areas of the economy. Water Hyacinth on Lake Victoria in Kenya has led to a decrease in beach property values and dwindled fish resources thus altering economic gains.

Economic Factors

Though destructive, some invasive species have been of benefit to mankind. Historically, several invasive species have been used for medicinal, agricultural and ornamental purposes. The Purple loosestrife (Lythrum Salicaria) has been preferred by gardeners for generations now because of its seed production and beauty. Arictium minus’ roots are used as a traditional medicinal herb, a remedy for dry skin and sore throat treatment. Invasive species have also been used to prevent soil erosion and fight the spread of deserts. However, most of these turn out to be destructive as they often stifle the growth of local species.


Invasive species have raised international concern. Governments, Non-Governmental Organizations (NGOs), regional bodies and different actors are spearheading different initiatives to tackle their spread. Different policies have been developed to help the affected areas as well as minimize the effects. This reaffirms the economic and environmental beliefs in a balanced ecosystem.

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