Forest soils: environmental and societal issues

Healthy forest ecosystems provide a wide range of services that underpin many of society's basic needs, economic processes and cultural and spiritual values. . In addition to supplying wood (energy and material) and non-timber products, forests provide a habitat for a wide variety of living organisms, help mitigate climate change by storing atmospheric carbon, regulate the water cycle, produce drinking water and provide numerous recreational benefits.

The functioning and health of temperate forests are intimately linked to the quality* of the soil that supports them. Indeed, the soil represents the reservoir that roots can explore to anchor the tree and supply it with minerals and water. But soil, because of its position at the interface between the atmosphere, the hydrosphere*, the lithosphere* and the biosphere*, is much more than just a support for plant growth; it is at the origin of seven interacting ecological functions:

• habitats for soil organisms and regulation of soil biodiversity: habitat support for soil organisms and interactions between organisms influencing their abundance and diversity (biological heritage);

• retention and supply of essential nutrients for living organisms and their development: nitrogen, phosphorus, potassium, calcium, magnesium, trace elements, etc. ;

• storage, recycling and transformation of endogenous and exogenous organic materials;

• infiltration, retention and circulation of water: useful reserves, leaching, runoff, percolation... ;

• filter, buffer and degrade organic and inorganic contaminants. It should be noted that the retention of contaminants in the soil, while purifying the water, entails a risk of transferring these contaminants to vegetation or other soil organisms (e.g. trace metals);

• stable physical support for plant establishment and development (anchoring and root growth);

• control of the chemical composition of the atmosphere via gas exchanges and contribution to climatic processes via energy exchanges between the soil and the atmosphere.

To be functional and provide these multiple services, the soil must be healthy. However, forest soils are faced with numerous pressures and disturbances, resulting in...