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The World Beneath Our Feet:
Soil Biodiversity and Ecosystem Functioning

Diana H. Wall
Natural Resource Ecology Laboratory, College of Natural Resources, Colorado State University, Fort Collins, Colorado 80523
Ross A. Virginia
Environmental Studies Program, Dartmouth College, Hanover, NH 03755

Ecological Services Provided by Soil Biodiversity

The Importance of soil fertility as a national resource was aptly noted by Franklin D. Roosevelt: “The nation that destroys its soils destroys itself” (Roosevelt 1937). Since then, the importance of soils and the organisms within them for many vital ecosystem processes has been identified, for example, cleansing of water, detoxification of wastes, and decay of organic matter. Indeed, it is now recognized that the functioning of soils, the dark material beneath our feet, is critical for the survival of life on the planet in its present form. Almost every phylum known above the ground exists below the surface of the ground (Brussaard and others 1997). Soil biota include the microorganisms (bacteria, algae, and fungi), protozoa (single-celled animals), microscopic invertebrates that are less than 1 mm long (such as rotifers, copepods, tardigrades, nematodes, and mites), larger invertebrates up to several centimeters long such as those easily seen by the naked eye—ants, snails, earthworms, spiders, termites and so on, and vertebrates. One cubic meter of soil can harbor millions of species of microorganisms and microscopic invertebrates—organisms whose identities and contributions to sustaining our biosphere are largely undiscovered.

Life in soil is recognized as an important part of Earth's overall biodiversity, yet few studies measure the taxonomic diversity of soil or the relationship of soil biodiversity to ecosystem structure and function (Pimentel and others 1997; Swift and Anderson 1994). Understanding of the relationship between biodiversity and ecosystem function in soils is critically needed if we are to manage and predict



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