This presentation is the introduction to the session, which will discuss the relationship between termites, soils and tree diversity in tropical forests. Termites are insects known to attack dead wood, especially in buildings, and also crops and newly planted trees, giving termites a bad reputation and making them feared by all. However, without termites the understorey of tropical forests would be covered with heaps of dead wood. So termites are definitely useful. In addition, termites also provide other services to humans, for food, poultry, agriculture, etc., and to the environment itself. Termites have a major impact on soil quality, particularly on soil richness by increasing the pH, and the carbon and moisture content. Large termite mounds are much sought after by farmers in the Kisangani region (DRC) as they provide evidence of high soil fertility. In addition, termite burrows increase the infiltration of runoff waters and the galleries improve soil aeration; termites cultivate fungi on organic matter, increasing soil carbon content, etc. Some termite mounds may be indicators of soil quality: for example, typical termite mounds are found in temporarily flooded areas. All this explains why many tree species are associated with termite mounds where they exhibit better growth. Termite diversity is very high, with about 4000 species (only 2600 known) and their distribution throughout the world shows how important it is to focus on termite impacts on the environment and forest diversity. (Texte intégral)