Submitted to: Encyclopedia of Soil Science
Publication Type: Book / Chapter
Publication Acceptance Date: 6/19/2001
Publication Date: 12/10/2001
Citation: Franzluebbers, A.J. 2001. Soil animals and ecosystem functioning. Encyclopedia of Soil Science. Interpretive Summary: This article is one of several contributions in the category Soil Ecology for the Encyclopedia of Soil Science. This article describes the classification of soil animals into microfauna (protozoa, rotifers, nematodes), mesofauna (tartigrades, collembola, mites), and macrofauna (millipedes, spiders, ants, beetles, and earthworms). The spatial distribution of soil animals is influenced by organic substrate placement, soil porosity, and presence of living plant roots. Soil animals facilitate the processes of decomposition, nutrient cycling, aggregation, macroporosity development, pest control, and development of soil biodiversity. A few key soil animals and their functions in soil are described.
Technical Abstract: Soil animals (fauna) are represented by a diverse array of creatures living in or on soil for at least a part of their life cycle. Based on body size, soil animals can be divided into microfauna, mesofauna, and macrofauna. Feeding activity is useful to distinguish among carnivores (predators and parasites), phytophages (feed on living plant materials), saprophages (feed don dead and decaying organic material), microphytic feeders (feed on bacteria, fungi, algae, and lichens), and miscellaneous feeders (not restrictive in their diet). Soil animals are not uniformly distributed in soil. Unlike the soil microflora, which could be considered ubiquitous, the proliferation of soil animal communities is more sensitive to environmental disturbances and ecological interactions. Soil animals work directly and indirectly in concert with the soil microflora to decompose organic matter and mineralize nutrients. Soil animals are active participants in the formation of soil structure, which is an important characteristic that influences water infiltration, soil water retention, and percolation. Intense competition among soil organisms keeps an ecosystem healthy by avoiding one organism to become dominant.