Feeding behavior of epi-anecic earthworm species and their impact on soil microbial communities

International audience

English. Earthworms contribute to numerous ecosystem services provided by soils. Most of the studies focusing on thecontributions of earthworms on leaf litter decomposition were conducted by comparing distinct ecological categories(epigeic, epi-anecic, anecic strict and endogeic), whereas their specific contributions within a givenecological category remains largely unknown. In this context, the aim of this study was to determine the contributionof four epi-anecic earthworm species (Lumbricus rubellus, Lumbricus festivus, Lumbricus centralis andLumbricus terrestris) to the leaf litter decomposition of three plant species (Lolium perenne, Holcus lanatus andCorylus avellana) with contrasted litter traits located at both the soil surface and at a depth of 10 cm. Fungal andbacterial communities inhabiting epi-anecic earthworm burrows were also assessed using T-RFLP analysis. Epianecicearthworms improved the leaf litter mass loss solely at the soil surface, while leaf litter mass loss wasmainly due to microbial activity at 10 cm deep. Leaf litter mass loss was positively correlated to the initialbiomass of the epi-anecic earthworms and the intensity of this relationship was dependent on litter type.Interestingly, L. festivus seemed to have a higher contribution to surface leaf litter mass loss that was linked to astimulation of the fungal communities in its burrows. Fungal communities were thus impacted by both the littertype and the epi-anecic earthworm identity whereas soil bacterial diversity and richness were stimulated in theearthworm burrows whatever the epi-anecic earthworm species considered. Overall, epi-anecic earthwormscontributed to enhance the diversity of the drilospheric microbiota.