The ecological scales of the community, ecosystem, and biome integrate many ecological processes (e.g., the environment, physiology, organisms, species, populations, interactions). At the community level, the organisms are associated with each other through their particular interactions and the physical characteristics of their habitat. The process of succession describes how a community develops through a sequence of steps over time. For example, as new land is exposed when a glacier retreats or on newly formed sand dunes, a community will develop over time through the process of succession. Lichens are plants that colonize rocky surfaces and breakdown the rock into the precursor of soil. Their action facilitates the colonizing of the area by other plants, e.g., forbs, grasses, shrubs, and finally trees. Along with succession in the plant community, animal species colonized the area and change in type and number as the community develops. Succession will also occur after
a community is removed - partially or completely - through natural or human events such as fire, major storms, volcanic activity, and clear cutting. Climate is the principal influence on the type and distribution of communities. Mediterranean (also known as "chaparral") communities, shrub steppe, and arctic tundra are some examples of many different types of communities. Ecologists who study this level of ecology are known as community ecologists.
The ecosystem is not defined by size or location. Rather it is the inclusion of energy flow and mineral cycles with all community-level characteristics that define an ecosystem. Ecologists who study ecosystems are known as synecologists and systems ecologists. The latter often use computer simulation modeling to study and understand the structure and function of ecosystems. Climate is also the major influence on the type and distribution of ecosystems.
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The biome is the highest scale of integration in ecology. Biomes are not fundamentally different from ecosystems, except that biomes are defined more by their geographic scale (often continental in size) and physiognomy (characteristic appearance over the landscape, e.g., grassland, woodland, coniferous and deciduous forest). The
noted ecologist, Robert Whittaker, classified a total of 36 terrestrial and aquatic biomes, which are summarized in his classic book, "Communities and Ecosystems" (1975).
Featured Books and journals
Biogeography: An ecological and
Cox, C.B., and P.D. Moore 2000. Sixth edition. Blackwell Science, Malden,
Ecology of world vegetation. Archibold,
O.W. 1995. Chapman and Hall.
Ecosystems of the World. Volumes 1 29.
Goodall, D.W., Editor in Chief.
International Biological Program. Volumes 1 26.
American terrestrial vegetation. Barbour, M.G., and W.D. Billings.
1988. Cambridge University Press, Cambridge, England.
Vegetation of the Earth. 1983. Walter, H.
Ecological Society of
British Ecological Society
Journal of Ecosystems