Earthworms as ecosystem engineers : a review

The concept of ecosystem engineering has emerged decades ago and highlights the direct or indirect modulation of available resources by organisms through their biological activities. Ecosystem engineers create biogenic structures (aggregates, burrows) that may serve as habitats for other species than themselves. This chapter aims at overviewing the key role played by earthworms as ecosystem engineers through their bioturbation activities involving soil mixing as well as their influence on the decomposition and mineralization of litter by breaking down organic matter, and their influence on the gas and water exchange or nutrient transfer in the soil. Focus is made on the engineering processes and especially the formation of biogenic structures in relation to soil structure (burrows, casts) in the framework of soil function interactions, particularly in the drilosphere. Special attention is paid to soil aggregates’ fabric and new tools that may help to discriminate their origin. Finally, management and ecosystem engineer’s future challenges will be highlighted regarding soil ecosystem services in the context of ecosystem restoration.