La biodiversité des sols

Commissariat général au développement durableMay 7, 2019

Les sols constituent un habitat pour la faune et la flore. Leurs propriétés physiques et leur composition chimique varient d’un sol à l’autre et au sein d’un même sol. Du fait de cette hétérogénéité, les sols abritent plusieurs milliers d’espèces (animaux, champignons, bactéries…). Ces organismes vivants protègent le sol de l’érosion ou du tassement, améliorent sa fertilité et participent à la dégradation des contaminants.

Soils constitute a habitat for fauna and flora. Their physical properties and chemical composition vary from one soil to another and within the same soil. Due to this heterogeneity, soils harbor several thousand species (animals, fungi, bacteria, etc.). These living organisms protect soil from erosion or compaction, improve its fertility, and participate in the degradation of contaminants.

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Bacteria in Soils
Favorable Conditions
Clay soils with high pH and rich organic carbon content provide the most favorable conditions for abundant microbial biomass. This biomass is generally more substantial in natural grassland and forest soils than in monoculture, vineyard, or orchard soils.
Human Activity Impact
It is also affected by soil disturbances linked to human practices (plowing, soil amendments, etc.).
Geographic Distribution
The richest soils are found in the East and mountain regions, while the poorest are located in the Landes, the North, and the Northwest.
Microbial Diversity
Soil type and land use, as well as practices, also influence microbial diversity. The least diverse bacterial communities are found in forests, the least disturbed ecosystems.
Soil Fauna
Earthworms
Regarding macrofauna, metropolitan soils host on average 260 earthworms per m². They are more abundant in grasslands and agroforestry areas. Conversely, the lowest abundances are observed in croplands and vineyard or forest environments.
Invasive Flatworms
• Subject to a recent citizen survey with support from the MNHN, invasive flatworms (terrestrial flatworms originating from Asia) have been identified in metropolitan France and overseas territories. They threaten soil balance and the fauna it harbors by exterminating native earthworms. • As of June 2015, more than half of the departments were affected by at least one of the six invasive exotic flatworm species present in metropolitan France. The West and South are particularly affected.

Further reading

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