Niche
One of the most important ideas associated with ecosystems is thenicheconcept. A niche
refers to the role a species or population plays in the ecosystem, with respect to all the
interactions with the abiotic and biotic components of the ecosystem. A shorthand definition
is that a niche is how an organism “makes a living”. Some of the important aspects of a
species’ niche are the food it eats, how it obtains the food, nutrient requirements, space, etc.
The different dimensions of a niche represent different biotic and abiotic variables. These
factorsmayincludedescriptionsoftheorganism’slifehistory, habitat, trophicposition(place
in the food chain), and geographic range.
Different species can hold similar niches in different locations, and the same species may
occupy different niches in different locations. Species of the Australian grasslands, although
different from those of the Great Plains grasslands, occupy the same niche.
Once a niche is left vacant, other organisms can fill in that position. When the tarpan (a
small, wild horse, chiefly of southern Russia) became extinct in the early 1900s, the niche
it left vacant has been filled by other animals, in particular a small horse breed, the konik
(Figure23.17).
Figure 23.17: The konik horse, which filled the niche left vacant by the tarpan, a horse that
became extinct in the early 1900s in southern Russia. ( 16 )
When plants and animals are introduced, either intentionally or by accident, into a new
environment, they can occupy the new niches or niches of native organisms, and sometimes
outcompete the native species, and become a serious pest. For example, kudzu, a Japanese
vine, was introduced intentionally to the southeastern United States in the 1870s to help