Soils are biosystems, habitats and reserves of biodiversity

Soils are biosystems whose functions and services are determined by the dynamics and activity of living organisms and environmental parameters, whether they are natural or of anthropic origins. Soil microorganisms consist of the following four major groups of energy and nutritional activities involved in the functioning of biogeochemical cycles: chemo-organotrophic (heterotrophic), chemolithotrophic (autotrophic), photolithotrophic, and photo-organotrophic organisms. Soil microorganisms can live in the presence or in the absence of oxygen. Soils provide mineral energy sources derived from their mineral constituents, used by chemolithotrophic organisms, and especially organic energy sources and photosynthates essentially originating from plants. Soil biodiversity is determined by heterogeneous environments on various scales. Similar to the tools of molecular biology and biochemistry, chemical and physical methods of analyzing soil constituents and their organization, and methods of data processing and modeling have also made considerable progress.