Résumé
Invertebrates play significant, but largely ignored, roles in the delivery of ecosystem services by soils at plot and landscape scales. They participate actively in the interactions that develop in soil among physical, chemical and biological processes. We show that soils have all the attributes of self-organized systems as proposed by Perry (Trends Ecol. Evol. 10 (1995) 241) and detail the scales at which invertebrates operate and the different kinds of ecosystem engineering that they develop. This comprehensive analysis of invertebrate activities shows that they may be the best possible indicators of soil quality. They should also be considered as a resource that needs to be properly managed to enhance ecosystem services provided by agro-ecosystems