BFE - Natural Ecosystem Changes (Lesson)

Natural Ecosystem Changes

Believe it or not, often the biotic balance in a community is maintained by a single species, known as the keystone species. A keystone species is a species whose very presence contributes to an ecosystem's diversity and whose extinction would consequently lead to the extinction of other forms of life. For example, fig trees are the keystone species in a tropical forest; likewise, wolves were introduced back into Yellowstone Park because without wolves to control the number of herbivores, the ecosystem was drastically changed. As a general rule, if the keystone species is removed from an ecosystem, then the ecosystem completely changes.

Indigenous species are those that originate and live or occur naturally in an area or environment. With increasing frequency, however, new species are being introduced into ecosystems by chance, by accident, or with intention. While some introduced species cannot find a niche and die out, many others are quite happy in their new environment and compete successfully with the indigenous species. One example of the harm that introduced species can do was seen when, in 1904, a fungus was introduced accidentally into deciduous forests of the eastern United States; thus fungus caused a blight that killed nearly all of the chestnut trees by the early 1950s. Be sure to read the section titled "Invasive Species" on the next page of this module.

 

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