Forest soil

Article By:

Bormann, Bernard T. Department of Forest Science, Oregon State University, Corvallis, Oregon.

Last reviewed:May 2021

DOI:https://doi.org/10.1036/1097-8542.269500

The natural medium for growth of tree roots and associated forest vegetation. Proper forest growth and management depend on many factors, including the quality of the forest soil (see illustration). In general, weathering of underlying rock, climatic factors (such as rain, wind, and temperature fluctuations), living organisms, topography, and disturbances (such as glacial action, flooding, erosion, and agriculture) interact over time to produce soil. Soil helps sustain the productivity and diversity of terrestrial life by serving as the source of nutrients and water for plants, by physically anchoring plants, and by serving as the habitat for soil organisms. Far more numbers and species of organisms live belowground than aboveground. Because soil usually develops quite slowly, soil conservation is important for maintaining the productivity of the land. Soil also acts as a water purifier; organic substances and most pollutants are arrested in upper soil horizons, purifying water before it enters streams or aquifers. In addition, soil is the repository of life; as plants and animals die, they become part of the soil. Overall, soil profiles reveal much about soil history and disturbances, including plant and animal remains, flooding, volcanic ash deposits, windthrow events (that is, events in which trees are uprooted by wind), rotting wood, charcoal from fires, and past human activities. See also: Forest; Forest ecosystem; Forestry; Soil; Soil ecology

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