Soil aggregation in a laboratory experiment: Interactions between earthworms, woodlice and litter palatability

SummaryInteractions between soil invertebrate functional groups are still poorly understood. In this study, the effect of the soil dwelling earthworm Aporrectodea caliginosa and the woodlouse Porcellio scaber (litter inhabitant), alone or in combination, on soil aggregation was investigated in laboratory microcosms with litter of different quality (Quercus robur and Fagus sylvatica). After 4 months of incubation, the aggregate size distribution was measured using a dry-sieving method. A. caliginosa played an important role in the formation of large aggregates (>2 mm), whereas P. scaber greatly influenced litter disappearance. A. caliginosa individuals formed a greater number of large aggregates when fed with beech leaves compared to oak leaves even though they preferred the latter. In the presence of beech and P. scaber, A. caliginosa produced significantly fewer large aggregates than expected.